Vitamin D3 insufficiency and colorectal cancer

Critical Reviews in Oncology/Hematology 88 (2013) 594–612

Vitamin D3 insufficiency and colorectal cancer Michelino Di Rosa a , Michele Malaguarnera a , Antonio Zanghì b , Antonino Passaniti c , Lucia Malaguarnera a,∗ a

c

Department of Bio-medical Sciences, University of Catania, Catania, Italy b Department of Surgery, University of Catania, Catania, Italy Department of Pathology and Biochemistry & Molecular Biology, University of Maryland School of Medicine, Baltimore, MD, USA Accepted 18 July 2013

Contents 1. 2. 3. 4. 5. 6. 7. 8.

9. 10. 11.

12. 13.

∗

Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1␣,25-dihydroxycholecalciferol synthesis, bio-availability, and activity in the colon . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Antineoplastic activity of 1␣,25-(OH)2 -D3 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Vitamin D receptor alterations and colon cancer progression . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Mechanisms responsible for VDR downregulation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . CYP27B1 and CYP24A1 alterations and colon cancer . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1␣,25-(OH)2 D3 dual regulation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Osteopontin (OPN) and E-cadherin: key players in vitamin D growth responses. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8.1. OPN regulation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8.2. E-cadherin regulation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8.3. ␤-Catenin regulation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8.4. Disruption of E-cadherin and OPN equilibrium . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . E-cadherin and vitamin D receptor in human colon carcinoma . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Role and regulation of DICKKOPF genes in colon cancer . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1␣,25(OH)2 D3 target genes involved in CRC . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11.1. The mitogen-activated protein kinase (JNK) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11.2. GTP-binding protein overexpressed in skeletal muscle (Gem) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11.3. Transient receptor potential-vanilloid 6 (TRPV6/CaT1/ZFAB) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11.4. Runt-related transcription factors (RUNX) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11.5. Kallikrein-related peptidase 6 (KLK6/protease M) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11.6. Bilirubin UDP-glucuronosyltransferase isozyme-2 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11.7. CST5 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11.8. SPROUTY-2 (SPRY2) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11.9. KDM6B/JMJD3 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11.10. MicroRNA-22 (miR22). . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . New expanding epigenetic modifiers regulated by 1␣,25(OH)2 D3 in CRC cells . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Future directions and concluding remarks . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Conflict of interest . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Reviewers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Biographies . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Corresponding author at: Via Androne, 83, 95124 Catania, Italy. Fax: +39 095 7807843. E-mail address: [email protected] (L. Malaguarnera).

1040-8428/$ – see front matter © 2013 Elsevier Ireland Ltd. All rights reserved. http://dx.doi.org/10.1016/j.critrevonc.2013.07.016

595 595 597 597 598 599 599 600 600 600 600 602 602 602 603 604 604 604 604 604 604 605 605 606 606 606 606 607 607 607 611

M. Di Rosa et al. / Critical Reviews in Oncology/Hematology 88 (2013) 594–612

595

Abstract Traditionally the main recognized function of vitamin D has been calcium and phosphate homeostasis. Nevertheless, recent evidences have highlighted the importance of vitamin D3 as a protective agent against various cancers. The association between CRC and vitamin D3 was first suggested in ecologic studies, but further was confirmed by observational studies in humans and experimental studies in both animal models and cellular lines. The protective role of vitamin D3 against cancer has been attributed to its influence of on cell proliferation, differentiation, apoptosis, DNA repair mechanisms, inflammation and immune function. In its active (calcitriol) form (1,25-dihydroxyvitamin D3[1␣,25-(OH)2 D3 ]) vitamin D3 and the nuclear vitamin D receptor (VDR) regulate hundreds of genes including those coding for proteins involved in cell differentiation and cell proliferation. The current review addresses some of the key mechanisms that influence the biological actions of vitamin D and its metabolites. The insights derived from these mechanisms may aid in designing new uses for this hormone and its non-hypercalcemic derivatives in the treatment and/or prevention of CRC. © 2013 Elsevier Ireland Ltd. All rights reserved. Keywords: Vitamin D3; Colorectal cancer; Antineoplastic activity

1. Introduction The mammalian form of vitamin D3 (cholecalciferol), a fat-soluble prohormone, is generated endogenously in the skin by ultraviolet light-mediated metabolism of the precursor sterol 7-dehydrocholesterol or is obtained, to a lesser extent, from nutritional sources [1]. The active form 1␣,25(OH)2 D3 acts as a steroid chemical messenger in numerous target tissues, in what is known as the vitamin D endocrine system [2]. The discovery of vitamin D receptor (VDR) expression in normal human tissues including the hair follicle, immune cells [3,4], muscle, adipose tissue, bone marrow [5], colorectal epithelium [6] and in cancer cells has expanded the role of the vitamin beyond bone homeostasis [2]. Associations between sunlight exposure, dietary habits, and tumor incidence in various epidemiological investigations indicate an important role for vitamin D in cancer risk [7]. Whereas the primary function of 1␣,25-(OH)2 D3 is to regulate calcium absorption and maintain mineral homeostasis, upon binding to its cognate receptor (VDR), 1␣,25-(OH)2 D3 also decreases the proliferation and enhances the differentiation of CRC cells as well as alters the transcription of a large number of genes involved in inhibiting carcinogenesis [8]. The protective role of vitamin D against cancer has been recognized from its involvement in a number of different regulatory pathways. The anti-proliferative, pro-differentiating or pro-apoptotic effects of 1␣,25-(OH)2 D3 depend largely on the differentiation status, the VDR expression level, and the cancer cell type [9]. CRC is one of the major causes of cancer deaths worldwide. Multiple factors are responsible for the etiology of this cancer since the colorectal mucosa is directly influenced by nutrients reaching the colonic lumen and mucosal cells. Principally, the loss of genomic stability can lead to cancer development by facilitating acquisition of mutations in DNA repair genes, in tumor-suppressor genes, and in oncogenes [10]. Epigenetic silencing by aberrant DNA methylation that leads to inactivation of mismatch repair genes may also occur [11]. Familial (inherited) forms of CRC are characterized by early onset and (in the case of familial polyposis) by high

numbers of colonic polyps that promptly develop toward malignancy even in juveniles. Conversely, sporadic CRC is a disease of advancing age and requires several decades to progress into a clinically symptomatic disease. Therefore, because of its slow evolution, the latter can be promoted, and its outbreak delayed or prevented, by lifestyle and dietary choices [12]. The risk of CRC increases rapidly when people migrate from low to high-risk countries, suggesting that local environmental exposure influences susceptibility of CRC [12,13]. Lifestyle and diet can contribute to progression of early malignant colonic lesions by modulating growth factors that interact with inflammatory pathways. The propensity of Vitamin D to prevent CRC was supposed for more than a quarter of a century. One of the first clues indicating this link was the finding of an inverse relationship between mean solar radiation and age-adjusted CRC death rates [13]. Since that time, a number of studies have suggested a link between vitamin D and/or calcium levels and the incidence of human CRC formation [14]. An association between vitamin D status and reduced risk of CRC has been found in ethnically diverse populations [15]. Recent evidence confirmed an inverse association between serum 25(OH) D3 levels and CRC risk, but no clear association with total cancer mortality was observed [16]. In this review we discuss the mechanisms by which vitamin D insufficiency may lead to CRC pathogenesis, as well as the mechanisms responsible for resistance to 1␣,25-(OH)2 D3 in order to design more rational future clinical trials.

2. 1␣,25-dihydroxycholecalciferol synthesis, bio-availability, and activity in the colon The prohormone (cholecalciferol) is hydroxylated to 25hydroxycholecalciferol [25(OH) D3] by the 25-hydroxylase. The activity of the hepatic 25-hydroxylase is not under tight physiologic regulation, and thus the circulating concentration of the inactive form 25(OH) D is determined mainly by sunlight exposure and dietary intake. Although 25OHD is the most abundant form of vitamin D in the blood, it

596

M. Di Rosa et al. / Critical Reviews in Oncology/Hematology 88 (2013) 594–612

has minimal capacity to bind to the vitamin D receptor and elicit a biological response. Further hydroxylation by 1␣-hydroxylase (CYP27B1) to the main biologically active hormone, 1␣,25-dihydroxycholecalciferol [1␣,25-(OH)2 D3 or calcitriol], occurs in the proximal renal tubule [17]. Sufficient renal production of 1␣,25-(OH)2 D3 leads to activation of the catabolic pathway by 24-hydroxylation of 1␣,25(OH)D3 , or of 25(OH)-D3 . A major part of 25(OH)-D3 and of 1␣,25-(OH)2 -D3 is bound in plasma to a vitamin D binding protein (DBP, 85–87%), which modulates bioavailability and influences responsiveness in some end-organs or to albumin (12%). Only unbound vitamin D sterols are biologically active. Free 1␣,25-(OH)2 -D3 entering into cells binds the vitamin D receptor (VDR) and forms a heterodimeric complex with retinoid X-receptor (RXR) [18]. The VDR–RXR complex associates with a hexameric binding motif in the promoter region of the vitamin D response element (VDRE) [19]. After recruitment of cofactors to the protein-DNA complex, VDR acts as a ligand-dependent transcription factor for vitamin D-responsive genes [20]. The great majority of tissues expressing VDR also contain the enzyme CYP27B1. It has been suggested that CYP24A1 is undetectable in vitamin D target cells unless induced by 1␣,25-(OH)2 -D3 through a VDR-mediated mechanism [21]. In addition to the widespread presence of VDR and CYP27B1, 1␣,25(OH)2 D3 shows highly tissue-specific functional effects on hormone secretion [22], immune function [3], cell differentiation, and cell growth [23]. Production of intracellular 1,25(OH)2 -D3 is crucial for regulation of cell functions as demonstrated by the finding that VDR-mediated actions depended more on megalin-mediated endocytosis of 25(OH)D3 than on ambient 1␣,25-(OH)2 -D3 levels [24]. Initially, the direct function of 1␣,25-(OH)2 -D3 and 25-OH-D3 in colorectal epithelia was debated. These controversies were resolved by the finding that human colonic mucosal cells were able to synthesize 1␣,25-(OH)2 -D3 from its precursor 25(OH)-D3 [25,26]. In particular was suggested that 1␣,25-(OH)2 -D3 , synthesized and accumulated in the colon mucosa, could prevent tumor progression by autocrine/paracrine mechanisms [25]. Unlike to renal calcitriol synthesis, the local 25(OH)D3level could become restrictive for colonic synthesis, which could cause modifications of specific cell functions leading to transformation of colonocytes. Additionally was found that 1␣,25-(OH)2 -D3 down-regulates both CYP27B1 and VDR expression in colonocytes [27]. Therefore, sufficient levels of the substrate for colonic synthesis of the active metabolite as well as regulation of the vitamin D synthesizing enzyme 1-alpha hydroxylase (CYP27B1) and vitamin D catabolic enzyme 24-alpha hydroxylase (CYP24A1) could be crucial for CRC prevention [27]. At the same time 1␣,25-(OH)2 D3 induces CYP24A1, which increases dramatically during progression of colon tumors to a poorly differentiated state (G3-G4). Although CYP27B1 expression is reduced [28], it seems that the major mechanism for vitamin D resistance or reduced sensitivity to calcitriol in VDR-positive cells may be 1␣,25-(OH)2 -D3 and 25(OH)-D3 catabolism

via the CYP24A1 hydroxylation pathway. At low serum levels of 25(OH)-D3 , CYP27B1 activity in extrarenal cells may not be enough to maintain the steady-state tissue concentrations of 1␣,25-(OH)2 -D3 required for normal cellular growth and differentiation to counteract hyperproliferation. In fact, CYP27B1 expression was found lower in tissue derived from CRC patients than that derived from normal colon [6,25]. The hypothesis that adequate amounts of 25(OH)-D3 are essential for protection against colonic hyperproliferation was reinforced by the evidence that the anti-mitogenic effect of 1␣,25-(OH)2 -D3 was induced even when human colon carcinoma cells were treated with 25(OH)-D3 , but only if cells were CYP27B1-positive and expressed low CYP24A1 activity [27]. If 1␣,25-(OH)2 -D3 stored in colonic mucosa has the capability to prevent premalignant progression, the effective colonic tissue concentration of 1␣,25-(OH)2 -D3 would be determined not only by substrate availability but also by other regulatory factors similar to those in renal vitamin D synthesis. Hence, a strong autocrine/paracrine antimitogenic action of 1␣,25-(OH)2 -D3 would retard further tumor growth as long as cancer cells maintain a certain degree of differentiation, high levels of CYP27B1 activity, and VDR expression. The protective effects of vitamin D as a dietary factor against CRC were confirmed by studies in animal models. Wild-type mice fed a Western-style diet (low vitamin D and calcium content with high fat and phosphate) exhibited hyperproliferation in colonic epithelial cells in the absence of carcinogen exposure [29]. Short periods on this diet induced colon-crypt hyperplasia [30], but, these effects were suppressed when the Western-style diet was supplemented with calcium and 1␣,25-(OH)2 -D3 , indicating that hyperproliferation could be prevented by increasing the dietary calcium and 1␣,25-(OH)2 -D3 content [31]. A Western-style diet was also tested in the mutant Apcmin mice carrying a truncated Apc allele with a nonsense mutation in exon 15 (Apc1638), which leads to the development of multiple neoplasia throughout the intestinal tract soon after birth. The number of polyps were increased by the Western-style diet and mice survival diminished [31]. But, Apcmin mice treated with 1␣,25-(OH)2 -D3 for 10 weeks showed a significant decrease in the total tumor load (sum of all polyp areas) over the entire gastrointestinal tract. Combined evidence from human and experimental animal studies strongly suggests that consumption of highfat diets causes a change in the pattern of hepatic bile acid secretion, resulting in higher relative levels of deoxycholic and lithocholic acid (LCA) in bile. A diet low in fiber also reduces the excrement volume, an effect that may cause the increased fecal concentration of bile acids [32]. A highfat diet leads to colon LCA accumulation, which induces DNA damage and inhibits DNA repair enzymes in colonic cells. Consequently, LCA promotes colon cancer in experimental animals and high levels of LCA have been found in CRC patients [33]. Vitamin D deficiency leads to inadequate 1␣,25-(OH)2 -D3 synthesis in colonocytes and an ineffective autocrine/paracrine regulation of cellular growth and function. This state can be aggravated by specific interaction

M. Di Rosa et al. / Critical Reviews in Oncology/Hematology 88 (2013) 594–612

of bile acids with the vitamin D endocrine system [34]. Bile acids are structurally similar to vitamin D and, therefore, compete as ligands for the VDR [35], antagonizing the chemopreventive effects of 1␣,25-(OH)2- D3 on colorectal cancer. In particular, LCA is able to mimic some VDR-mediated actions of 1␣,25-(OH)2 -D3 such as intestinal calcium absorption and mobilization of calcium from bone [36] and upregulation of CYP24 [37], which catabolizes LCA itself and enhances catabolism of 1␣,25-(OH)2 -D3 , further deteriorating its protective actions against colorectal cancer growth [36]. Interestingly, colonic tumorigenesis in response to LCA can be suppressed by supplemental administration of 1␣,25-(OH)2 -D3 [38]. Paradoxically, activation of VDR by LCA or 1␣,25-(OH)2 -D3 transcriptionally induced CYP3A, steroid- and bile acid-sulfotransferase (Sult2A1), and multidrug resistance-associated protein 3 (MRP3) expression in a feed-back mechanism that resulted in colon LCA elimination [39]. Since the MRP3 is localized to the basolateral face of enterocytes and mediates LCA release into the bloodstream [40], these coordinated mechanisms for LCA detoxification could partly explain the protective action of 1␣,25-(OH)2 -D3 against CRC.

3. Antineoplastic activity of 1␣,25-(OH)2 -D3 As mentioned earlier, the protective role of vitamin D against cancer results from the inhibition of proliferation, the increase in differentiation, and the induction of apoptosis. These regulatory events can operate in combination and the mechanisms differ depending on cell type [41]. The anti-proliferative effect of 1␣,25-(OH)2 -D3 acts to prevent the cell from entering the S-phase of the cell cycle, blocking the cell cycle at the G1/S transition by increasing the expression of cyclin dependent kinases (p21 and p27), thus inhibiting further growth [42]. VDRE are present in the p21 gene promoter which induce p21 expression from 1␣,25(OH)2 -D3 /VDR-dependent gene transcription. However, the p27 gene, which lacks VDRE, is induced by the transcription factors NF-Y and Sp1 as well as by protein stabilization [43] (Fig. 1). The 1␣,25-(OH)2 -D3 potentiates its antiproliferative activity by interfering with various signaling pathways that control epithelial cell growth. For instance, activation of the EGF pathway seems to allow colon carcinoma cells to escape from the anti-tumoral action of 1␣,25-(OH)2 -D3 [44]. It was reported that 1␣,25-(OH)2 -D3 reduced EGF receptor (EGFR) expression and decreased the amount of membrane EGFR, promoting its ligand-induced internalization [45]. Adenocarcinoma colon cells overexpress insulin-like growth factor (IGF)-II, which acts as a mitogen and survival agent. The 1␣,25-(OH)2 -D3 mediated its antineoplastic action by interfering with the IGF-II signaling pathway, inhibiting IGF-II secretion, and increasing the production of IGF-binding protein-6, which negatively modulates IGFII signaling [46]. Type II IGF receptor (IGFR-II) was also increased, which blocked this pathway since it accelerates

597

IGF-II degradation [47]. The pattern of expression of the co-activators (SRC-1, CBP, GRIP-1/TIF-2, and others) and co-repressors (NCoR, SMRT, Alien) [48] that interact with VDR and the activation of other signaling pathways such as that of TGF␤ [49] may be responsible for the effects of 1␣,25-(OH)2 -D3 . It has been reported that 1␣,25-(OH)2 -D3 induces the expression of type I TGF␤ receptor and IGFRII to sensitize SW480 and CaCo-2 cell lines to the growth inhibitory action of TGF␤ [50]. Reduced responsiveness to the inhibitory effects of TGF-␤ may be an important event in the loss of growth control in colorectal carcinogenesis and the progression from colonic adenoma to carcinoma [51]. In addition, SMAD3, a TGF␤ signaling downstream protein, binds to SRC-1 and cooperates with VDR in the induction of 1␣,25-(OH)2 -D3 target genes [49]. In many CRC cell lines and in SW480-ADH cells, a subpopulation of SW480 colon adenocarcinoma cells that express VDR, 1␣,25-(OH)2 -D3 and several analogs induced epithelial differentiation, which was accompanied by the expression of E-cadherin, the main component of adherens junctions and responsible for the maintenance of the epithelial phenotype [52]. In 1␣,25-(OH)2 -D3 -treated cells, a conspicuous brush-border membrane has been observed with high activity of brush-border-associated enzymes, such as alkaline phosphatase, which is commonly considered a colon differentiation marker [53]. Moreover, 1␣,25-(OH)2 -D3 is also able to exert anti-proliferative actions by regulating several genes linked to proliferation, including c-FOS, c-JUN, and c-MYC [54] (Fig. 1). Once malignant transformation has occurred, 1␣,25-(OH)2 -D3 plays a crucial role in regulating the genes that control death pathways and inducing apoptosis [55]. 1␣,25-(OH)2 -D3 and its analogs upregulate the pro-apoptotic protein BAK [55] and promote the release of the antiapoptotic protein BAG-1 from the nucleus [56]. The effect of 1␣,25-(OH)2 -D3 on the expression of other proapoptotic factors such as BAX or anti-apoptotic factors such as BCL-2 and BCL-XL varies depending on the cell line [55]. Additionally, the finding that mutant p53 protein interacts with VDR and modulates the transcriptional activity of 1,25(OH)2 D3 resulting in the reduction of proapoptotic genes and in the increment of survival-promoting genes, confirms that 1,25(OH)2 D3 acts as an anti-apoptotic agent [56] (Fig. 1). Nevertheless, the report indicating that the apoptosis potentiated by 1,25(OH)2 D3 does not require an intact p53 [57] suggests that the use of 1␣,25-(OH)2 -D3 analogs for cancer treatment is independent of the tumor p53 status.

4. Vitamin D receptor alterations and colon cancer progression VDR is expressed in normal colon epithelial cells and in some colon cancer cells at variable levels [6]. Epidemiological data indicate that vitamin D receptor (VDR) signaling

598

M. Di Rosa et al. / Critical Reviews in Oncology/Hematology 88 (2013) 594–612

Fig. 1. The molecular mechanisms by which 1,25(OH)2 D3 mediates anti-cancer effects involve multiple pathways in cells expressing VDR. The anti-proliferative action of 1,25(OH)2 D3 involves down-regulation of insulin-like growth factors (IGFs) and up-regulation of IGF binding protein-3 (IGFBP-3). IGFPBs may have IGF-independent actions and can inhibit cancer growth and promote apoptosis directly. Transforming growth factor (TGF)-␤ secretion is induced by 1,25(OH)2 D3 and can play an important role in the growth inhibition. Activated cyclin/cyclin dependent kinase (CDK) complexes can be decreased by 1,25(OH)2 D3 . Exposure to 1,25(OH)2 D3 results in the accumulation of cells in the G0/G1 phase of the cell cycle. 1,25(OH)2 D3 induces apoptosis by decreasing the expression of the anti-apoptotic factors (Bcl-2, Bcl-XL ) and/or increasing the pro-apoptotic genes (Bax, Bad). 1,25(OH)2 D3 can also modulate angiogenesis by decreasing the expression of hypoxia-inducible factor-1 (HIF-1), a transcription factor that induces vascular endothelial factor (VEGF) production. Inflammation contributes to the development and progression of cancer. Prostaglandins (PGs) promote carcinogenesis and cancer progression by stimulating cellular proliferation, inhibiting apoptosis, promoting angiogenesis and activating carcinogens. 1,25(OH)2 D3 regulates the expression of PGs, suppressing the proliferative and angiogenic stimuli of PGs in malignant cells. Increased COX-2 expression is one of the key steps in carcinogenesis. Suppression of COX-2 is an important mechanism by which 1,25(OH)2 D3 inhibits angiogenesis. Nuclear Factor Kappa-B is an inducible transcription factor ubiquitously present in the cells and is an important regulator of innate immune responses and inflammation. Malignant cells have elevated levels of active NF␬B. 1,25(OH)2 D3 directly modulates basal and cytokines induced by NF␬B.

induced by its ligand, the active metabolite 1␣,25-(OH)2 D3 , has anti-cancer activity. Elevated VDR expression in CRC is associated with epithelial differentiation and favorable prognosis. However, in advanced carcinomas VDR expression decreases or entirely disappears, indicating that colon cancer cells express VDR as long as they retain a certain degree of differentiation [27,45]. Several polymorphisms have been described in the VDR gene, some of which have been associated with increased risk of colon cancer [58,59]. Specific mutations may cause deletions, frame-shift mutations, premature stop codons or splice site abnormalities that down-regulate VDR expression or binding activity during colon cancer progression. These effectively suppress key VDR actions resulting in ligand unresponsiveness and failure of therapy with vitamin D analogs.

5. Mechanisms responsible for VDR downregulation VDR downregulation is known to be associated with poor prognosis and cancer progression [60]. The functional role of VDR in colon has been examined in vdr–null mice. These mice exhibit decreased markers of cellular proliferation and increased levels of markers reflecting DNA oxidative stress [61], indicating that the vitamin D-receptor complex acts by attenuating oxidative DNA damage and preventing hyperproliferation and malignant transformation. Numerous transcription factors such as Wilm’s tumor suppressor, Zeb-1, Cdx-2, and Sp1 are able to induce VDR expression [62]. In contrast, the transcription factors Snail1 and Snail2 repress VDR expression in colon cancer cells suggesting a role for SNAIL in the downregulation of VDR, which was observed in advanced colon tumors [63]. The transcription factors Snail1

M. Di Rosa et al. / Critical Reviews in Oncology/Hematology 88 (2013) 594–612

and Snail2 belong to the Snail family of zinc-finger transcription factors and modulate cell movement during embryonic development and tumor progression. Cellular overexpression of Snail1 or Snail2 induces the epithelial-to-mesenchymal transition (EMT), which entails the loss of epithelial characteristics and the acquisition of a mesenchymal fibroblastic phenotype [64]. Consequently, the expression of Snail1 or Snail2 in carcinoma cells promotes their migratory and invasive properties favoring tumor invasion and metastasis [65]. The overexpression of Snail1 or Snail2 in human colon cancer cells decreases VDR expression and strongly inhibits the regulation of 1␣,25-(OH)2 -D3 target genes such as CDH1/Ecadherin, p21CIP1 , and CYP24A1. Thus, Snail blocks the inhibitory effect of 1␣,25-(OH)2 -D3 on the Wnt/␤-catenin signaling pathway [66] and prevents epithelial differentiation induced by 1␣,25-(OH)2 -D3 in colon cancer cells. Even in the presence of 1␣,25-(OH)2 -D3 , VDR repression by Snail1 and Snail2 induces EMT, which causes transcriptional changes such as the repression of CDH1/E-cadherin, of OCLN/occludin, several claudins, ZO-1, cytokeratin 18 and MUC-1, and the induction of mesenchymal genes such as FN1/fibronectin, VIM/vimentin, LEF1, and several matrix metalloproteases [65]. The overexpression of either SNAI1 or SNAI2 in individual tumors correlates with VDR downregulation [67], which is stronger in the tumors that express both SNAI1 and SNAI2 than in those expressing only one of these genes, suggesting that both Snail1 and Snail2 exert an additive effect on the VDR gene promoter in cultured human colon cancer cells [68]. Other studies showed that SNAI1 overexpression correlates with VDR downregulation both in the tumor and in the normal adjacent tissue, indicating that SNAIL1 induces the release of paracrine signals from the tumoral cells to the surrounding normal cells [60]. This could explain the unresponsiveness to vitamin D compounds of the normal tissue bordering the tumor. Furthermore, SNAIL up-regulation enhances invasive properties and metastatic potential [69]. It has been observed that colon cancer patients, with high levels of SNAIL1 and SNAIL2 and lower VDR expression, are resistant to therapy with vitamin D compounds. Therefore, the level expression of SNAIL1 and SNAIL2 could be used as an indicator of patient adequacy to this treatment and so can be regarded as a marker of tumor malignancy [70]. Additionally, the secreted proteins FGF, EGF, TGF␤, and Wnt have been established as promoters of SNAIL expression [71].

599

stage malignancy, expression of the synthesizing hydroxylase CYP27B1 is increased similarly to that of the VDR, whereas during outright human malignancy in high-grade colon tumors this expression is repressed. Up-regulation of both VDR and CYP27B1 can be considered intrinsic tumor suppressive functions. In low-grade malignant lesions, CYP27B1 expression is remarkably high and the increase of newly synthesized 1␣,25-(OH)2 -D3 in the colonic mucosa could be responsible for upregulation of the transcriptional activity of CYP24A1 [26] and consequently for inhibition of tumor cell growth. Thus, not only are adequate serum levels of the precursor 25(OH)D3 essential, but also optimal expression of the 1␣-hydroxylating enzyme CYP27B1. The vitamin D3 catabolizing hydroxylase, CYP24A1, is highly expressed during colon cancer progression, indicating that colonocytes are released from normal growth control by the steroid hormone [25]. Alterations in the expression of vitamin D hydroxylases in the course of tumor progression in colon cancer patients seems to be caused by epigenetic regulation of gene activity via methylation/demethylation processes, along with histone acetylation/deacetylation. It has been reported that a negative response element in the CYP27B1 promoter is regulated by the ligand-activated VDR through recruitment of histone deacetylase, a critical step for chromatin structure remodeling to suppress the CYP27B1 gene [73]. Genetic association studies reported that a polymorphism of CYP24A1 (IVS4-66T>G) showed a statistically significant association with risk of colon cancer overall, but particularly for proximal colon cancer. When stratified by anatomic site, a statistically significant association was found for three CYP24A1 polymorphisms with risk of distal colon cancer. In addition, a possible interaction between CYP27B1 and UV-weighted sun exposure with proximal colon cancer was detected [74]. Moreover, three splice variants of CYP24A1 in human colon tissue samples displayed a correlation with histological type of the tissue and gender of patients. The sequencing of the alternatively spliced fragments showed that two had lost the mitochondrial targeting domain, while the third lacked the heme-binding domain. All splice variants retained their sterol binding domain. Translation of these variants would lead to a dysfunctional enzyme without catalytic activity that still binds its substrates; these variants might compete for substrate with the synthesizing and catabolizing enzymes of vitamin D [75].

7. 1␣,25-(OH)2 D3 dual regulation 6. CYP27B1 and CYP24A1 alterations and colon cancer Efficient synthesis of the active vitamin D metabolite depends essentially on sufficient serum levels of the precursor 25(OH)-D3 . Equally important is the controlled expression and activity of the synthesizing (CYP27B1) and catabolic (CYP24A1) hydroxylases. Normally, in the colon, CYP27B1 and CYP24A1 are expressed at low levels [72]. At early

Tissue-specific 1␣,25-(OH)2 -D3 growth responses and its different biological effects arise from the induction of rapid non-genomic action, extending from seconds to hours, or via genomic action occurring at the transcriptional level, over hours to days [76]. The diverse targets of 1␣,25-(OH)2 D3 non-genomic or genomic actions include G-coupled receptors, inter- and intra-cellular signaling genes, cellcycle regulators, metabolic function moieties, cell adhesion

600

M. Di Rosa et al. / Critical Reviews in Oncology/Hematology 88 (2013) 594–612

molecules, and extracellular matrix components [77]. The anti-proliferative and pro-differentiating effects of Vitamin D are attributed almost exclusively to genomic action mediated by binding of the hormonal metabolite 1␣,25(OH)2 -D3 to the nuclear VDR which subsequently acts as a ligand-activated regulator of gene transcription [78]. This was experimentally demonstrated using a murine model expressing a mutant VDR with an intact hormone-binding domain, but lacking the first zinc finger necessary for DNA binding, which abrogated both the genomic and non-genomic functions of 1␣,25(OH)2 -D3 [79]. The genomic effects of 1␣,25(OH)2 D3 are implicated in the induction of osteopontin (OPN) [2]. However, they appear dispensable for induction of E-cadherin in colorectal cells [80].

8. Osteopontin (OPN) and E-cadherin: key players in vitamin D growth responses Inside cellular integrated networks, OPN and E-cadherin play important roles in growth responses to vitamin D. OPN and E-cadherin are functionally antagonistic growth regulatory genes that are modulated by 1␣,25-(OH)2 -D3 through overlapping but distinct molecular mechanisms [81]. The E-cadherin/OPN expression balance may provide a useful biologically-based marker of this complexity, which is implicated in 1␣,25-(OH)2 D3 growth responses. 8.1. OPN regulation OPN is a key vitamin D target gene, regulated by 1␣,25-(OH)2 D3 -mediated non-genomic [80] and genomic [82] mechanisms. OPN is an extracellular matrix glycophosphoprotein implicated in osteoblast differentiation [80], but, is also a central effector of vitamin D-mediated anchorage-independent growth [83]. OPN may abrogate the adhesion requirement for cell growth and enhance cell invasion through Matrigel by activation of Ran GTPase (RAN) [84]. The 1␣,25-(OH)2 -D3 transcriptional regulation of OPN involves VDR/RXR heterodimer binding and recruitment of coregulators including SRC-1, -2, -3, CBP, p300 and DRIP205 to VDREs within the OPN promoter [82] (Fig. 2). Through crosstalk with VDR/VDRE, these membrane-mediated kinase cascades may influence cell-specific biological responses to 1␣,25-(OH)2 -D3 , thus coordinating diverse physiological and patho-biological processes. Further, OPN mRNA activated by VDR non-genomic actions involves Ca2+ -influx and rapid activation of the small GTPAse, RhoA and its effector, Rho-associated coiled kinase (ROCK) [80] (Fig. 2). The 1␣,25-(OH)2 D3 rapid activation of cytosolic kinases may phosphorylate critical co-activators resulting in modulation of VDR-dependent gene transcription [84]. Mutation in one or both VDRE sites in the rat OPN promoter functionally suppressed 1␣,25-(OH)2 D3 -mediated transcription of an OPN-promoter luciferase reporter construct [85]. By non-genomic actions,

1␣,25-(OH)2 -D3 can modulate a repertoire of cytosolic kinases and second messenger systems that show some level of cell- or tissue-specificity including activation of protein kinase A in enterocytes [86]. 8.2. E-cadherin regulation E-cadherin is a transmembrane linker protein of the intercellular adherens junctions that play a crucial role in the preservation of the adhesive and polarized phenotype of epithelial cells [87]. During the transition from adenoma to carcinoma reduced E-cadherin expression is a common event and affects the alteration of the normal epithelial phenotype and the acquisition of invasive capacity [88]. Ecadherin is regarded as a tumor suppressor gene and its loss is a predictor of poor prognosis [89]. E-cadherin is induced by 1␣,25-(OH)2 -D3 via non-genomic rapid actions [81], which suppress cell growth [89]. Similar to OPN, the 1␣,25-(OH)2 -D3 -mediated induction of E-cadherin involves transcription-independent promotion of Ca2+ -influx and consequent activation of RhoA–ROCK signaling. Subsequent to these events, induction of p38/MAPK-MSK1 signaling upregulates E-cadherin and inhibits β-catenin/Tcf transcriptional activity [80] (Fig. 2). However, this response appears to be more robust than that of OPN [80]. 8.3. β-Catenin regulation ␤-Catenin is a proto-oncogene encoding a cytoskeletonassociated protein, which in normal epithelial cells is bound mostly to the cytoplasmic tail of E-cadherin at the adherens junctions [90]. ␤-catenin activity is regulated by transport between the nucleus and plasma membrane where its binding partner E-cadherin is located. In the cell nucleus, ␤-catenin binds members of the TCF/lymphoid enhancer-binding factor (LEF)-1 family and thus regulates gene expression [91] (Fig. 2). The blockade of ␤-catenin transcriptional activity and the induction of E-cadherin, which is lost in the adenoma to carcinoma transition, is essential for the tumor phenotypic transition toward a normal epithelial phenotype that is induced by 1␣,25-(OH)2 -D3 [81]. Most colorectal cancers exhibit a deregulated ␤-catenin signaling pathway caused by several genetic mutations in adenomatous polyposis coli (APC), a negative regulator of Wnt signaling [92], or ␤-catenin itself that lead to the constitutive activation of ␤-catenin target genes due to aberrant proteasomal degradation [93]. In SW480-ADH cells, 1␣,25(OH)2 D3 inhibits the transcriptional activity of ␤-catenin by two mechanisms. First, it enhances the amount of VDR bound to ␤-catenin, thus reducing the interaction between ␤-catenin and TCF4. This effect is independent of E-cadherin, as it takes places in LS174T cells that lack E-cadherin expression [67]. Secondly, the reduction of ␤-catenin transcriptional activity caused by 1␣,25(OH)2 D3 is accompanied by the nuclear export of ␤catenin and its relocalization to the plasma membrane, an effect that is abolished by SNAIL1 [67] (Fig. 2).

M. Di Rosa et al. / Critical Reviews in Oncology/Hematology 88 (2013) 594–612

601

Fig. 2. Osteopontin (OPN) and E-cadherin are functionally antagonistic growth regulatory genes modulated by 1␣,25-(OH)2 -D3 . OPN activates RAN phosphorylation, which is involved in cell proliferation. The 1␣,25-(OH)2 -D3 transcriptional regulation of OPN involves VDR/RXR heterodimer binding and recruitment of SRC-1, -2, -3, CBP, p300 and DRIP205 to VDREs within the OPN promoter. E-cadherin and OPN are reciprocally regulated through ␤-catenin/Tcf and related signaling pathways. The 1␣,25-(OH)2 -D3 -mediated induction of both E-cadherin and OPN involve promotion of Ca2+ -influx and activation of RhoA–ROCK signaling. Subsequently, induction of p38/MAPK-MSK1 signaling upregulates E-cadherin and inhibits ␤-catenin/Tcf transcriptional activity. ␤-catenin activity is regulated by transport between the nucleus and plasma membrane. In the cell nucleus, ␤-catenin binds TCF/LEF-1 and regulates gene expression. Wnt/␤catenin promotes proliferation and blocks differentiation. Free ␤-catenin is sequestered by E-cadherin and is phosphorylated by glycogen synthase kinase 3 (GSK3)-␤, leading to the accumulation of free ␤-catenin. 1␣,25(OH)2 D3 inhibits the transcriptional activity of ␤-catenin by enhancing the amount of VDR bound to ␤-catenin, and reducing ␤-catenin transcriptional activity, which is accompanied by the nuclear export of ␤-catenin and its re-localization to the plasma membrane. This effect is abolished by SNAIL-1. 1␣,25(OH)2 D3 downregulates the Wnt/␤-catenin signaling pathway. Mutation of ␤-catenin blocks GSK-3␤ phosphorylation, so, ␤-catenin accumulates in the nucleus, leading to both the activation of genes involved in the control of cell proliferation and invasiveness such as c-myc, cyclin D1, c-jun PPAR-␥ peroxisome proliferator-activated receptor-gamma and other proliferative genes. Members of the DICKKOPF gene family (DKK-1, DKK-2 and DKK-4) are extracellular Wnt inhibitors, differentially regulated by 1␣,25(OH)2 D3 .

Upon ␤-catenin stabilization in colon cancer cells, due to its own mutation or that of APC or AXIN, binding to VDR may buffer its stimulatory action on TCF4 target genes, thus providing a protective effect that may be lost along with VDR expression during malignant progression. The loss of E-cadherin is involved in the EMT and in progression to the metastatic stage. E-cadherin facilitates ␤-catenin accumulation and translocation to the nucleus where it modulates the expression of Tcf/Lef-1-target genes implicated in cell proliferation [93]. Mutations in the TCF-4 gene may contribute to this process [94]. Nuclear ␤-catenin transiently potentiates VDR transcriptional activity before ␤-catenin is

exported from the nucleus and/or VDR-mediated transcription is turned off [67]. The effects of ␤-catenin on VDR transcriptional activity have been attributed to the interaction between the activator function (AF)-2 domain of the VDR and the C-terminal region of ␤-catenin [90]. Furthermore, acetylation of the ␤-catenin C-terminal region differentially regulates its ability to activate LEF/TCF or VDR-regulated promoters. The mutation of a specific residue in the AF-2 domain also transcriptionally inactivates VDR, in contrast retaining VDR binding to the hormone and its interaction with ␤-catenin and ligand-dependent activation of VDREcontaining induces. Interestingly, VDR antagonists, which

602

M. Di Rosa et al. / Critical Reviews in Oncology/Hematology 88 (2013) 594–612

block the VDRE-directed activity of the VDR and recruitment of classical coactivators, still allow VDR to interact with ␤-catenin, which suggests that these and other ligands could permit those functions of the VDR that involve ␤catenin interaction [90]. An interesting implication of this observation is that ␤-catenin may not be an exclusive activator of LEF/TCF target genes (Fig. 2). The interaction of ␤-catenin with other transcription factors may contribute to the pleiotropic effects of the Wnt pathway, which has different target genes in different cell types. 8.4. Disruption of E-cadherin and OPN equilibrium E-cadherin and OPN are reciprocally regulated through ␤-catenin/Tcf and related signaling pathways [95]. Disturbance of this balance during the early stages of multistep tumorigenesis influences cell migration [88], adhesion [96], invasion [97] leading to the development of abnormal molecular mechanisms promoting cancer. The evidence that VDR controls functionally antagonistic growth regulatory pathways, involving the ␤-catenin/E-cadherin/OPN equilibrium, was demonstrated by using stably transformed subclones with variable constitutive expression of these genes and the parental Rama 37, a cellular line with epithelial-like morphology. This cell line expresses high levels of Ecadherin, weak expression of OPN [95] and low levels of ␤-catenin signaling activity and of Tcf-1. No growth effects were observed in Rama 37 cells having low OPN and high E-cadherin expression. In contrast, 1␣,25-(OH)2 D3 treatment in Rama 37 stably transfected subclones that had high OPN and/or low level E-cadherin induced small but significant increases in cell attachment to fibronectin, anchorage-independent growth or invasion [86]. Molecular crosstalk was observed between the antagonistic VDRdependent signals and those ␤-catenin/Lef-1/Tcf molecules modulated by VDR-mediated activation of OPN. Even if molecular cross-talk was observed, the growth effects induced by 1␣,25-(OH)2 -D3 or analogs were dependent on the constitutive balance of these functionally antagonistic molecules in target cells. These studies clarified the essential mechanisms and linked the tissue-specific differences of VDR growth-regulatory networks, particularly involving OPN and E-cadherin, to epidemiological associations between serum 25(OH)-D3 levels and cancer.

9. E-cadherin and vitamin D receptor in human colon carcinoma The expression of VDR and E-cadherin could be diagnostic hallmarks of low-grade carcinoma in colon cancers [59,68]. 1␣,25(OH)2 D3 inhibits proliferation and promotes differentiation of human colon cancer cells also via the induction of the tumor suppressor CST5/cystatin D. Free ␤-catenin that is sequestered by E-cadherin is rapidly phosphorylated by glycogen synthase kinase3 beta (GSK3␤) in

the APC/axin/GSK-3␤/casein kinase I complex and is subsequently ubiquitinated and degraded. Interaction of Wnt ligands with their membrane receptors blocks GSK3␤, leading to the accumulation of free ␤-catenin [98] (Fig. 2). Mutation of either APC or β-catenin blocks GSK-3␤ phosphorylation resulting in reduced APC-regulated nuclear export [99]. As a result, ␤-catenin accumulates in the nucleus. Consequently, the genes involved in the control of cell proliferation and invasiveness such as c-myc, cyclin D1, peroxisome proliferator-activated receptor (PPAR)-γ, matrilysin, c-jun, fra 1, uPA receptor, fibronectin, CD44, Tcf-1, Cdx-1 and gastrin (Fig. 2) result activate. In contrast, the expression of DRCTNNB1A and differentiated epithelial markers such as ZO-1 result inhibited [100,101]. It has been shown that phosphatidylinositol-5-phosphate 4kinase type II beta (PIPKIIb) but not PIP-KIIa is required for VDR-mediated E-cadherin induction in SW480-ADH cells and that the modulation of nuclear PI(4,5)P2 signaling affects this process. The syntenin-2 postsynaptic density protein/disk large/zona occludens (PDZ) domain and pleckstrin homology domain of phospholipase C-delta1 (PLCd1 PHD) possess high affinity for phosphatidylinositol-4,5bisphosphate [PI(4,5)P2 ], mainly localized to the nucleus and plasma membrane, respectively. The expression of syntenin2 PDZ but not PLCd1 PHD inhibits 1␣,25(OH)2 D3 -induced E-cadherin upregulation, suggesting that nuclear PI(4,5)P2 production mediates E-cadherin expression through PIPKIIb in a VDR-dependent manner. PIPKIIb is also involved in the suppression of the cell motility induced by 1␣,25(OH)2 D3 . The transcriptional machinery involved in PI signalingdependent E-cadherin upregulation is an important issue to be resolved. One of the candidates is a putative tumor suppressor gene, Brg1, which is a catalytic ATPase subunit of the chromatin-remodeling complex regulated by PI(4,5)P2 [52]. Brg1 is involved in several chromatin remodeling processes mediated by nuclear receptors, and it was identified as a VDR-interacting protein in the WSTF-containing multiprotein complex “WINAC”. Because the loss or deletion of Brg1 is frequently observed in a variety of tumor cells [102], Brg1 could mediate E-cadherin expression under the control of PIPKIIb activity through VDR activation. Overall, these findings indicate that PIPKIIb-mediated PI(4,5)P2 signaling is important for E-cadherin upregulation and inhibition of cellular motility induced by VDR activation [52]. Therefore, PIPKIIb acts as a regulator of tumor progression. The potentiation of PIPKIIb activity could be an effective therapeutic target to prevent the malignant progression of VDR-positive colon cancers.

10. Role and regulation of DICKKOPF genes in colon cancer Among the numerous genes modulated by 1␣,25(OH)2 D3 , the extracellular Wnt inhibitors DKK-1 and DKK-4, members of the DICKKOPF gene family, have

M. Di Rosa et al. / Critical Reviews in Oncology/Hematology 88 (2013) 594–612

been found to be differentially regulated by 1␣,25(OH)2 D3 . By an indirect transcriptional mechanism, 1␣,25(OH)2 D3 increases the expression of DKK-1 RNA and protein, which acts as a tumor suppressor in human colon cancer cells harboring endogenous mutations in the Wnt/␤-catenin pathway (Fig. 2). Human DKK-1 has wide and complex effects on cell proliferation and differentiation, depending on the cell type. DKK-1 can inhibit tumorigenesis by different mechanisms. The transcription of the DKK-1 gene is enhanced by ␤-catenin/TCF acting on several sites in the promoter region [103]. DKK-1 is down regulated in colon cancer [103], indicating the loss of a negative feedback control of the Wnt/␤-catenin pathway in this neoplasia. Restoration of DKK-1 function in non-expressing cells bearing a truncated APC gene had no effect on ␤-catenin/T-cell factordependent transcription. However, DKK-1 overexpression induced tumor suppressor-like features such as reduced colony formation density and tumor growth inhibition in immunodeficient mice. These results suggest additional functions for DKK-1, other than inhibiting canonical Wnt signaling. In primary colorectal tumors, DKK-1 was found hypermethylated in 17% of the cases. Furthermore, the DKK1 promoter was selectively hypermethylated in advanced colorectal neoplasms [104]. In contrast, both SFRP-1 and WIF-1 methylation-associated silencing occurred across the spectrum of colorectal tumorigenesis. VDR transcriptional activity is required for DKK-1 induction and 1␣,25(OH)2 D3 has no effect on the half-life of DKK-1 mRNA. The slow kinetics of DKK-1 mRNA accumulation and the lack of VDR binding to the promoter region that is activated by the hormone strongly suggest that 1␣,25(OH)2 D3 up-regulates the transcription of DKK-1 via intermediate proteins encoded by early response genes not yet identified. The induction of DKK-1 by 1␣,25(OH)2 D3 constitutes a third mechanism by which this hormone antagonizes the Wnt/␤-catenin pathway. The existence of these mechanisms reinforces the importance of this pathway and of its regulation for the biology of the colonic epithelium. Another interesting finding is that DKK-1 is upregulated by ectopic E-cadherin in SW480-ADH cells and that a blocking antibody against E-cadherin inhibits 1␣,25(OH)2 D3 -mediated DKK-1 induction. This effect is slow and depends on the presence of a transcription-competent VDR [105]. These data strongly indicate that the regulatory effect of 1␣,25(OH)2 D3 is an indirect consequence of the induction of the epithelial adhesive phenotype [105]. The DKK-1 downregulation that was found in advanced, less differentiated tumors (Dukes’ stages C) seems to be due, in part, to promoter methylation [104]. The finding that DKK-1 expression is silenced by promoter methylation in a subset of advanced, typically dedifferentiated colorectal tumors and the association of DKK-1 with the differentiated phenotype suggest the interesting hypothesis that DKK-1 silencing is not only associated with, but also plays a role in the dedifferentiation process. This may thus explain the correlation between DKK-1 and VDR expression

603

in human tumors, which are lost during colon cancer progression along with that of E-cadherin, parallel to the upregulation of SNAIL1. DKK-4 RNA levels increased in patients with colon cancer [96,97] whereas they are undetectable in normal adjacent tissue [106]. In the adult, DKK-4 is not expressed or its levels are very low. DKK-4 protein has been characterized as an antagonist of Wnt/␤-catenin signaling [106]. DKK-4 is a target gene induced by Wnt/␤-catenin that is upregulated in colon tumors where it has been shown to increase cell migration and invasion and to promote angiogenesis. DKK-1 and DKK-4 are differentially regulated by 1␣,25(OH)2 D3 in human CRC. While the induction of DKK-1 by 1␣,25(OH)2 D3 is slow and requires intermediate proteins [105], 1␣,25(OH)2 D3 mediated repression of DKK-4 is rapid and is regulated by direct VDR binding to its gene promoter region [106]. Both DKK-1 and DKK-4 proteins have ␤-catenin-independent activities that, however, differ markedly. While DKK-1 has antitumoral effects [52], DKK-4 upregulation in colon cancer suggest tumor-promoting activity [106]. Therefore, the induction of DKK-1 and the repression of DKK-4 by 1␣,25(OH)2 D3 may contribute to its protective effects against this neoplasia. DKK-4 is a weaker Wnt inhibitor than DKK-1, although its effect is increased if Kremen 2 is overexpressed [107]. In apparent contradiction, DKK-4 inhibits the Wnt/␤catenin pathway and is overexpressed in several pathological diseases including some types of cancer [108]. Although DKK-4 can act as a Wnt inhibitor, these findings support new roles for this protein in human colon cancer, probably by inducing ␤-catenin-independent actions during the progression of this neoplasia. Wnt antagonists other than DKK-4 are also upregulated and may contribute to tumorigenesis in different systems [109]. DKK-4 has been shown transcriptionally induced by canonical Wnt signaling during ectodermal appendage morphogenesis [110]. Recently strong DKK-3 expression has been detected in CRC [111,112] and it has been proposed that DKK-3 might be a marker for endothelial cell activation during tumor angiogenesis [110]. Epigenetic silencing of the DKK-3 gene by promoter methylation was found to be a common event in gastric cancer and was associated with a poor outcome in such patients [112]. Overall, the data obtained so far confirm that 1␣,25(OH)2 D3 exerts a complex set of regulatory actions leading to the inhibition of the Wnt/␤-catenin pathway in colon cancer cells that is in line with its protective effect against CRC.

11. 1␣,25(OH)2 D3 target genes involved in CRC Transcriptomic studies performed in colon cancer cell lines using oligonucleotide microarrays revealed that 1␣,25(OH)2 D3 affected the mRNA expression levels of numerous genes, including many involved in transcription, cell adhesion, DNA synthesis, apoptosis, redox status and intracellular signaling. Some of these genes are responsive to 1␣,25(OH)2 D3 and may, therefore, represent important

604

M. Di Rosa et al. / Critical Reviews in Oncology/Hematology 88 (2013) 594–612

mediators of the effects of 1␣,25(OH)2 D3 . However, not all of these gene promoters contain the VDRE consensus sequence, which suggests that their regulation might be indirectly a consequence of the cascade of events induced by 1␣,25(OH)2 D3 . Many of these genes could be involved in the antiproliferative action of 1␣,25(OH)2 D3 . Several 1␣,25(OH)2 D3 target genes are upregulated, while other genes are downregulated after 1␣,25(OH)2 D3 treatment. 11.1. The mitogen-activated protein kinase (JNK) JNK is a member of the mitogen-activated protein kinase (MAPK) family, which plays an important role in the regulation of basic cellular processes such as development, differentiation, proliferation, regulation of transcription, and apoptotic cell death. The JNKs are encoded by three different JNK loci and are activated by various stimuli [113]. One of the down-stream targets of JNK is the transcription factor AP-1, which is a multiprotein complex composed of the gene products of the jun, fos and ATF genes [114]. Microarray studies in colon cancer cell lines showed that different jun family members (c-jun, JunD, JunB) were upregulated after 1␣,25(OH)2 D3 exposure [105]. These results were confirmed by other observations reporting increased expression of JNK and of members of the jun family after 1,25(OH)2 D3 or analog treatment [115] (Fig. 3). 11.2. GTP-binding protein overexpressed in skeletal muscle (Gem) Gem is a member of the RGK family of GTP-binding proteins belonging to the Ras superfamily [116]. The function of Gem is the inhibition of Rho kinase (ROK)mediated cytoskeletal rearrangement and the expression of voltage-gated calcium channels at the cell surface [116]. By reducing calcium-mediated cell growth, Gem is able to inhibit cell proliferation [116]. The antiproliferative effects of 1,25(OH)2 D3 in CaCo-2 cells may be also stimulated by an interaction of Gem and Sorcin, which is also upregulated by 1,25(OH)2 D3 action [117], is a calcium-binding protein regulating intracellular calcium release. The interplay between these two new 1,25(OH)2 D3 target genes may affect calcium channel activity and consequently cell growth (Fig. 3). 11.3. Transient receptor potential-vanilloid 6 (TRPV6/CaT1/ZFAB) TRPV6 is the principal calcium transporter in intestinal epithelial cell membranes and is involved in 1,25(OH)2 D3 mediated active calcium absorption in the intestine and in other organs with high calcium transport requirements [118]. TRPV6 is a direct vitamin D target gene [119]. Transcript levels of TRPV6/CaT1/ZFAB were also

induced by 1,25(OH)2 D3 in colon cancer cell lines (Fig. 3).

11.4. Runt-related transcription factors (RUNX) The Runt-related transcription factors (RUNX1, RUNX2 and RUNX3) play an important role in normal development and carcinogenesis [120]. Of the three genes, RUNX3 has been shown to be specifically associated with gastrointestinal tract development [121]. All three RUNX genes have the potential for involvement in CRC etiology given their role in signaling cascades mediated by TGF-␤ and bone morphogenetic protein (BMP) [122]. These RUNX genes interact with Smads, which are also involved in the TGF-␤ signaling pathway [122]. It has been suggested that 1,25(OH)2 D3 might be able to modulate the transcriptional activity of Runx1, Runx2 or Runx3 in tissues expressing VDR by enhancing the interaction of VDR and Runx [123]. Nevertheless, only RUNX2 appears modulated by the Vitamin D3 prohormone, cholecalciferol [124]. Cholecalciferol increased RUNX2 DNA binding at nanomolar concentrations even in cells with low VDR. Both cholecalciferol and 25(OH)2 D3 selectively inhibited cell proliferation in RUNX2-positive cells, but not in cells lacking RUNX2 expression. These compounds may have application in modulating RUNX2 activity in the metastatic setting and tumor angiogenesis [125] (Fig. 3).

11.5. Kallikrein-related peptidase 6 (KLK6/protease M) Another gene commonly upregulated by 1␣,25(OH)2 D3 in colon cancer cells is KLK6/protease M. KLK6 is a member of the kallikrein gene family of serine proteases implicated in various physiological processes ranging from cellular homeostasis to tissue remodeling [126]. Expression of KLK6 is frequently dysregulated in cancer [127], but its physiological role is still unknown. Transcript levels of KLK6 are higher in CRC tissue. The KLK6 gene is transcriptionally regulated by steroid hormones and treatment with 1␣,25(OH)2 D3 or its analogs increase expression of KLK6 [128] (Fig. 3).

11.6. Bilirubin UDP-glucuronosyltransferase isozyme-2 The UDP-glucuronosyltransferase gene is part of the glucuronidation pathway, which act to transform lipophilic molecules (drugs, bilirubin or steroids) into water-soluble and excretable metabolites. In 1,25(OH)2 D3 -deficient rats it has been observed that 1␣,25(OH)2 D3 regulates several biotransformator genes [129]. The finding that UDPglucuronosyltransferase is upregulated by 1␣,25(OH)2 D3 , indicate that 1,25(OH)2 D3 may be essential for the detoxification and the protection against environmental toxins [130] (Fig. 3).

M. Di Rosa et al. / Critical Reviews in Oncology/Hematology 88 (2013) 594–612

605

Fig. 3. 1,25 (OH)2D3 target genes involved in CRC.

11.7. CST5 The CST5 gene is a tumor suppressor gene that encodes cystatin D, an inhibitor of several cysteine proteases of the cathepsin family. It has been reported that a strong induction of cystatin D by 1␣,25(OH)2 D3 mediates the antiproliferative and pro-differentiation effects of 1,25(OH)2 D3 in CRC cells [130]. A direct correlation between cystatin D and VDR protein levels was found in human CRC biopsies, suggesting that 1␣,25(OH)2 D3 also regulates cystatin D in vivo [131]. In addition, ectopic cystatin D inhibits proliferation, migration, and anchorage-independent growth of cultured CRC cells and growth of xenografted tumors in mice. Cystatin D expression is also downregulated during colorectal tumorigenesis and is associated with tumor dedifferentiation [131].To date, the mechanism by which CST5 mediates its actions is not clear. Experiments using mutant cystatin D proteins with reduced anti-proteolytic activity

indicate that some of its anti-tumor effects may be independent of cathepsin inhibition [131] (Fig. 3). 11.8. SPROUTY-2 (SPRY2) SPROUTY-2 (SPRY2), an intracellular modulator of EGFR and other growth factor tyrosine kinase receptors, is involved in the regulation of cell growth, migration and angiogenesis [132]. SPROUTY-2 inhibits the intercellular adhesion induced by 1␣,25(OH)2 D3 , and gain- and loss-of-function experiments have shown that SPROUTY-2 and E-cadherin are repressed reciprocally in CRC cell lines and have opposite actions on cell differentiation [133]. In particular, in xenografted tumors the expressions of SPROUTY-2 and Ecadherin are mutually exclusive and are inversely correlated in human CRC biopsies, where SPROUTY-2 is upregulated in undifferentiated high-grade tumors and at the invasive front of low-grade carcinomas [133]. Therefore, SPROUTY-2 is

606

M. Di Rosa et al. / Critical Reviews in Oncology/Hematology 88 (2013) 594–612

inhibited by 1␣,25(OH)2 D3 and is a potential novel marker of malignancy and a therapeutic target in CRC (Fig. 3). 11.9. KDM6B/JMJD3 KDM6B/JMJD3 is a histone H3 lysine demethylase with an important gene regulatory role in development and may have an important tumor suppressor function [134]. 1␣,25(OH)2 D3 induces the expression of the KDM6B/JMJD3 gene [135]. JMJD3, in part, mediates prodifferentiative, anti-proliferative and gene regulatory actions of 1␣,25(OH)2 D3 , as well its antagonism in the WNT/␤catenin pathway. In SW480-ADH colon cancer cells, JMJD3 knockdown or expression of an inactive mutant JMJD3 fragment decreased the induction by 1,25(OH)2 D3 of several target genes and of an epithelial adhesive phenotype. Moreover, JMJD3 knockdown upregulated the epithelial-tomesenchymal transition inducers SNAIL1 and ZEB1 and the mesenchymal markers fibronectin and LEF1, while it downregulated the epithelial proteins E-cadherin, Claudin-1 and Claudin-7. Interestingly, the expression of JMJD3 RNA was found lower in tumor tissue than in normal tissue in 56% of human colorectal tumors and directly correlates with that of VDR [134] (Fig. 3). 11.10. MicroRNA-22 (miR22) miR22 is induced by 1␣,25(OH)2 D3 in a time-, doseand VDR-dependent manner and is required for the antiproliferative and anti-migratory effects of 1␣,25(OH)2 D3 in colon cancer cells. Its expression is lower in tumor than in normal tissue and correlates directly with VDR RNA expression, suggesting that miR22 is also a 1␣,25(OH)2 D3 target in vivo and may contribute to the anti-tumoral action of 1␣,25(OH)2 D3 in human colon cancer [136] (Fig. 3).

12. New expanding epigenetic modifiers regulated by 1␣,25(OH)2 D3 in CRC cells Other interesting example of genes activated by 1␣,25(OH)2 D3 in colon cancer cells are several members of the peptidylarginine deaminase gene family (PADI) [137], a class of enzymes that convert histone methylated residues of arginine to citrulline [138]. Recent comparative proteomic analysis have also identified several 1,25(OH)2 D3 -regulated proteins in CRC cells. Interestingly, most of the identified proteins were nuclear and others were cytoskeleton-associated proteins. A large group of these proteins, such as SFPQ, SMARCE, KHSRP, TARDBP and PARP1, were involved in RNA processing or modification and have been ascribed to the spliceosome compartment of human cells, suggesting a role of 1,25(OH)2 D3 in alternative splicing, which is frequently altered in cancer. In addition, 1,25(OH)2 D3 regulates the expression of a few cytoskeletal and actin-binding proteins

ERM (Ezrin, Radixin, Moesin) family, VCL, CORO1C, ACTB, some of which perform transcription-related functions in the cell nucleus in addition to modulating cell morphology and adhesion [139] (Fig. 3)

13. Future directions and concluding remarks The integration of the use of vitamin D to prevent and/or treat CRC is becoming increasingly important. In fact, patients receiving the maximum benefit from calcium supplementation were those with decreased serum levels of 1␣,25(OH)2 D3 [140]. The anti-carcinogenesis effects of supplemental calcium and vitamin D3 may in part depend on the ability of these agents to modulate favorably the expression of the CaR, the VDR, CYP27B1, and CYP24A1 in the colorectal mucosa [141]. Moreover, calcium and vitamin D3 supplementation modulate the colorectal mucosa molecular phenotype inhibiting proliferation and promoting cellular differentiation and apoptosis. It has been reported that that the administration of 800 IU/day vitamin D3 and/or 2 g/day calcium for 6 months enhanced apoptosis in the normal human colorectal epithelium upregulating Bax expression alone or relative to Bcl-2 expression, this finding suggested that Bax expression alone or in combination with Bcl-2 expression, may be a treatable biomarker of risk for colorectal neoplasms [142]. In the same study was observed a reduced expression of the marker for long-term proliferation (hTERT) in the upper part of the crypt [142]. The Women’s Health Initiative (WHI) WHI trial evaluating the effect of calcium and vitamin D on the risk of developing invasive colorectal cancer reported that cancer deaths from colorectal cancer were not significantly reduced [143]. Contrasting results reported that improving vitamin D nutritional status substantially reduced all-cancer risk in postmenopausal women [144]. These data sustained the previous finding of Trivedi et al. showing that mortality from cancer was reduced, although not significantly [145]. Another study in WHI reported contrasting effects of calcium and vitaminD by concurrent estrogen therapy on colorectal cancer risk [146]. Since the therapeutic use of 1␣,25(OH)2 -D3 is strictly limited by its propensity for causing toxic hypercalcemia, great effort has been directed at synthesizing compounds that mimic the chemical structure of the hormone to enhance its anti-tumor effects. Synthetic analogs are now available with structural modifications that reduce the calcemic activity and consequently hypercalcaemia and hypercalciuria, but retain effective cell regulatory properties [11]. Among such compounds are the secosteroid MC-903 (calcipotriol) and a similar analog EB-1089. Both MC-903 and EB-1089 inhibit the proliferation of malignant colorectal epithelial cells in the same way as the active metabolite 1␣,25(OH)2 -D3 [147]. A novel class of vitamin D analogs have been developed that possess a second side-arm, identical to the 1␣,25(OH)2 -D3 original side arm, and thus have been named Gemini vitamin

M. Di Rosa et al. / Critical Reviews in Oncology/Hematology 88 (2013) 594–612

D analogs (DG) [148]. DG are selective vitamin D receptor modulators (SVDRM), which are particularly well suited for anti-cancer therapy due to their ability to reduce tumor volume and mass and to prevent the invasive spread of the colon tumor, without producing the side effect of elevated serum calcium levels. DG’s potent anti-metastatic activities are especially important as it is well established that patients with more metastatic colorectal cancer (lymph node positive) have a poorer prognosis than patients without signs of metastasis [149]. DG showed enhanced anti-proliferative activity at lower concentration compared to 1␣,25(OH)2 -D3 . Additionally, the effect of DG on tumor metastasis was so potent that it completely prevented the tumor cells from invading the surrounding muscle. In comparison, 1␣,25(OH)2 -D3 administered at a 10-fold higher dose was not sufficient to exert anti-metastatic activity: fifty percent of the mice treated with 1␣,25(OH)2 -D3 had colorectal tumor cell invasion into the surrounding muscle. Furthermore, even though the concentration of 1␣,25(OH)2 -D3 provided to the mice was too low to have anti-tumor effects, it did cause significantly elevated levels of serum calcium and loss in body mass. Animals treated with DG had normal serum calcium levels and body mass. It is of interest to pursue the development of SVDRMs that can serve as potential cancer therapies by targeting cancer metastasis. This is because Vitamin D3 analogs could be used for the management of CRC metastatic disease for which there is no effective therapy [150]. Additional experimental data suggested that a useful approach for CRC prevention and treatment could be a combination of butyrate with 1␣,25(OH)2 -D3 . Both compounds induced the cell-growth arrest of human colon cancer cells [150]. Butyrate induced cell differentiation which was further enhanced after the addition of 1␣,25(OH)2 -D3 . The differentiated phenotype gained by the treated cells was preserved even when both compounds were removed. Furthermore, 1␣,25(OH)2 -D3 and butyrate synergistically induced p21CIP1 expression and alkaline phosphatase activity in CaCo-2 cells [91]. This effect was mediated by butyrateinduced overexpression of VDR. Therefore, it is possible that the synergistic effects of butyrate and 1␣,25(OH)2 -D3 are dependent on butyrate-induced upregulation of VDR. While butyrate alone increased expression of p21CIP1 combined exposure to butyrate and 1␣,25(OH)2 -D3 resulted in synergistic amplification. Butyrate-induced differentiation and p21CIP1 expression occurred via upregulation of VDR [151]. These strategies suggest that Vitamin D3 may function as a cellular stressor, much like radiation or chemotherapy, and could have its most effective results in combination with targeted therapies [152]. A different rational approach for combination therapies could lead to the activation of Ecadherin while avoiding up-regulation of OPN and may be a useful approach for pre-neoplastic states characterized by high constitutive OPN. Such future directions may provide a rationale for improving prevention and treatment of different cancers through VDR-mediated growth control. Vitamin D analogs may be helpful in the treatment of tumors in which

607

the Wnt pathway is activated inappropriately. The in vivo reproducibility of the anti-proliferative effect of synthetic vitamin D3 analogs could have a prophylactic therapeutic role in controlling the accelerated epithelial cell proliferation observed in hyperproliferative gastrointestinal disorders that predispose to the development of cancer. This could have future utility as palliative chemotherapeutic agents to control locally advanced or metastatic colorectal neoplasia.

Conflict of interest The authors declare any financial and personal relationships with other people or organizations that could inappropriately influence this work.

Reviewers Giovanni Li Volti, MD, PhD, Viale Andrea Doria, 6, Catania, Italy. Veronika Fedirko, PhD, Department of Epidemiology, Rollins School of Public Health, Emory University, Atlanta, GA, United States.

References [1] Holick MF. Vitamin D: a millennium perspective. Journal of Cellular Biochemistry 2003;88:296–307. [2] Norman AW. Minireview: vitamin D receptor: new assignments for an already busy receptor. Endocrinology 2006;147:5542–8. [3] Di Rosa M, Malaguarnera M, Nicoletti F, Malaguarnera L. Vitamin D3: a helpful immuno-modulator. Immunology 2011;134:123–39. [4] Di Rosa M, Malaguarnera G, De Gregorio C, Palumbo M, Nunnari G, Malaguarnera L. Immuno-modulatory effects of vitamin D3 in human monocyte and macrophages. Cellular Immunology 2012;280:36–43. [5] Wang Y, Zhu J, DeLuca HF. Where is the vitamin D receptor? Archives of Biochemistry and Biophysics 2012;523:123–33. [6] Matusiak D, Murillo G, Carroll RE, Mehta RG, Benya RV. Expression of vitamin D receptor and 25-hydroxyvitamin D31{alpha}-hydroxylase in normal and malignant human colon. Cancer Epidemiology, Biomarkers & Prevention 2005;14:2370–6. [7] Holick MF, Chen TC. Vitamin D deficiency: a worldwide problem with health consequences. The American Journal of Clinical Nutrition 2008;87:1080S–6S. [8] González-Sancho JM, Larriba MJ, Ordó˜nez-Morán P, Pálmer HG, Mu˜noz A. Effects of 1alpha, 25-dihydroxyvitamin D3 in human colon cancer cells. Anticancer Research 2006;26:2669–81. [9] Deeb KK, Trump DL, Johnson CS. Vitamin D signalling pathways in cancer: potential for anticancer therapeutics. Nature Reviews Cancer 2007;7:684–700. [10] Peltomäki P. Mutations and epimutations in the origin of cancer. Experimental Cell Research 2012;318:299–310. [11] Donehower LA, Creighton CJ, Schultz N, Shinbrot E, Chang K, Gunaratne PH, et al. MLH1-silenced and non-silenced subgroups of hypermutated colorectal carcinomas have distinct mutational landscapes. Journal of Pathology 2013;229:99–110. [12] Mishra J, Drummond J, Quazi SH, Karanki SS, Shaw JJ, Chen B, et al. Prospective of colon cancer treatments and scope for combinatorial

608

[13]

[14]

[15]

[16]

[17]

[18]

[19]

[20]

[21]

[22]

[23]

[24]

[25]

[26]

[27]

[28]

[29]

[30]

M. Di Rosa et al. / Critical Reviews in Oncology/Hematology 88 (2013) 594–612 approach to enhanced cancer cell apoptosis. Critical Reviews in Oncology/Hematology 2013;86:232–50. Grant WB. Role of solar UVB irradiance and smoking in cancer as inferred from cancer incidence rates by occupation in Nordic countries. Dermatoendocrinology 2012;4:203–11. Zhang X, Giovannucci E. Calcium, vitamin D and colorectal cancer chemoprevention. Best Practice & Research Clinical Gastroenterology 2011;25:485–94. Woolcott CG, Wilkens LR, Nomura AM, Horst RL, Goodman MT, Murphy SP, et al. Plasma 25-hydroxyvitamin D levels and the risk of colorectal cancer: the multiethnic cohort study. Cancer Epidemiology, Biomarkers & Prevention 2010;19:130–4. Freedman DM, Looker AC, Abnet CC, Linet MS, Graubard BI. Serum 25-hydroxyvitamin D and cancer mortality in the NHANES III study (1988–2006). Cancer Research 2010;70:8587–97. Cheng JB, Levine MA, Bell NH, Mangelsdorf DJ, Russell DW. Genetic evidence that the human CYP2R1 enzyme is a key vitamin D 25-hydroxylase. Proceedings of the National Academy of Sciences of the United States of America 2004;101:7711–5. Bouillon R, Carmeliet G, Verlinden L, van Etten E, Verstuyf A, Luderer HF. Vitamin D and human health: lessons from vitamin D receptor null mice. Endocrine Reviews 2008;29:726–76. Carlberg C. Current understanding of the function of the nuclear vitamin D receptor in response to its natural and synthetic ligands. Recent Results in Cancer Research 2003;164:29–42. Torchia J, Glass C, Rosenfeld MG. Co-activators and co-repressors in the integration of transcriptional responses. Current Opinion in Cell Biology 1998;10:373–83. Meyer MB, Goetsch PD, Pike JW. A downstream intergenic cluster of regulatory enhancers contributes to the induction of CYP24A1 expression by 1␣,25-dihydroxyvitamin D3. Journal of Biological Chemistry 2010;285:15599–610. Demay MB, Kiernan MS, DeLuca HF, Kronenberg HM. Sequences in the human parathyroid hormone gene that bind the 1,25dihydroxyvitamin D3 receptor and mediate transcriptional repression in response to 1,25-dihydroxyvitamin D3. Proceedings of the National Academy of Sciences of the United States of America 1992;89:8097–101. Gurlek A, Pittelkow MR, Kumar R. Modulation of growth factor/cytokine synthesis and signaling by 1alpha, 25-dihydroxyvitamin D(3): implications in cell growth and differentiation. Endocrine Reviews 2002;23:763–86. Rowling MJ, Kemmis CM, Taffany DA, Welsh J. Megalin mediated endocytosis of vitamin D-binding protein correlates with 25-hydroxycholecalciferol actions in human mammary cells. Journal of Nutrition 2006;36:2754–9. Holt PR, Arber N, Halmos B, Forde K, Kissileff H, McGlynn KA, et al. Colonic epithelial cell proliferation decreases with increasing levels of serum 25-hydroxy vitamin D. Cancer Epidemiology, Biomarkers & Prevention 2002;11:113–9. Cross HS, Nittke T, Kallay E. Colonic vitamin D metabolism: implications for the pathogenesis of inflammatory bowel disease and colorectal cancer. Molecular and Cellular Endocrinology 2011;347:70–9. Lechner D, Kallay E, Cross HS. 1␣,25-Dihydroxyvitamin D(3) downregulates CYP27B1 and induces CYP24A1 in colon cells. Molecular and Cellular Endocrinology 2007;263:55–64. Cross HS, Bareis P, Hofer H, Bischof MG, Bajna E, Kriwanek S, et al. 25-Hydroxyvitamin D(3)-1alphahydroxylase and vitamin D receptor gene expression in human colonic mucosa is elevated during early cancerogenesis. Steroids 2001;66:287–92. Risio M, Lipkin M, Newmark H, Yang K, Rossini FP, Steele VE, et al. Apoptosis, cell replication, and Western-style dietinduced tumorigenesis in mouse colon. Cancer Research 1996;56: 4910–6. Newmark HL, Lipkin M, Maheshwari N. Colonic hyperplasia and hyperproliferation induced by a nutritional stress diet with four

[31]

[32] [33]

[34]

[35]

[36]

[37]

[38]

[39]

[40]

[41]

[42]

[43]

[44]

[45]

[46]

[47]

components of Western-style diet. Journal of the National Cancer Institute 1990;82:491–6. Xue L, Lipkin M, Newmark H, Wang J. Influence of dietary calcium and vitamin D on diet-induced epithelial cell hyperproliferation in mice. Journal of the National Cancer Institute 1999;91: 176–81. Reddy BS. Diet and excretion of bile acids. Cancer Research 1981;41:3766–8. Nagengast FM, Grubben MJ, van Munster IP. Role of bile acids in colorectal carcinogenesis. European Journal of Cancer 1995;31A:1067–70. Peterlik M, Cross HS. Vitamin D and calcium deficits predispose for multiple chronic diseases. European Journal of Clinical Investigation 2005;35:290–304. Makishima M, Lu TT, Xie W, Whitfield GK, Domoto H, Evans RM, et al. Vitamin D receptor as an intestinal bile acid sensor. Science 2002;296:1313–6. Nehring JA, Zierold C, DeLuca HF. Lithocholic acid can carry out in vivo functions of vitamin D. Proceedings of the National Academy of Sciences of the United States of America 2007;104: 10006–9. Han S, Li T, Ellis E, Strom S, Chiang JY. A novel bile acid-activated vitamin D receptor signaling in human hepatocytes. Molecular Endocrinology 2010;24:1151–64. Kawaura A, Tanida N, Sawada K, Oda M, Shimoyama T. Supplemental administration of 1 alpha-hydroxyvitamin D3 inhibits promotion by intrarectal instillation of lithocholic acid in N-methyl-+N-nitrosourea-induced colonic tumorigenesis in rats. Carcinogenesis 1989;10:647–9. Thummel KE, Brimer C, Yasuda K, Thottassery J, Senn T, Lin Y, et al. Transcriptional control of intestinal cytochrome P-4503A by 1alpha, 25-dihydroxy vitamin D3. Molecular Pharmacology 2001;60:1399–406. McCarthy TC, Li X, Sinal CJ. Vitamin D receptor dependent regulation of colon multidrug resistance-associated protein 3 gene expression by bile acids. Journal of Biological Chemistry 2005;280:23232–42. Ordó˜nez-Morán P, Larriba MJ, Pendás-Franco N, Aguilera O, González-Sancho JM, Mu˜noz A. Vitamin D and cancer: an update of in vitro and in vivo data. Frontiers in Bioscience 2005;10: 2723–49. Scaglione-Sewell BA, Bissonnette M, Skarosi S, Abraham C, Brasitus TA. A vitamin D3 analog induces a G1-phase arrest in CaCo-2 cells by inhibiting cdk2 and cdk6: roles of cyclin E, p21 Waf1, and p27 Kip1. Endocrinology 2000;141:3931–9. Lin R, Wang TT, Miller WH, White JH. Inhibition of F-Box protein p45 SKP2 expression and stabilization of cyclindependent kinase inhibitor p27 KIP1 in vitamin D analog-treated cancer cells. Endocrinology 2003;144:749–53. Tong WM, Hofer H, Ellinger A, Peterlik M, Cross HS. Mechanism of antimitogenic action of vitamin D in human colon carcinoma cells: relevance for suppression of epidermal growth factor-stimulated cell growth. Oncology Research 1999;11:77–84. Sheinin Y, Kaserer K, Wrba F, Wenzl E, Kriwanek S, Peterlik M, et al. In situ mRNA hybridization analysis and immunolocalization of the vitamin D receptor in normal and carcinomatous human colonic mucosa: relation to epidermal growth factor receptor expression. Virchows Arch 2000;437:501–7. Oh YS, Kim EJ, Schaffer BS, Kang YH, Binderup L, MacDonald RG, et al. Synthetic low-calcaemic vitamin D(3) analogues inhibit secretion of insulin-like growth factor II and stimulate production of insulin-like growth factor-binding protein-6 in conjunction with growth suppression of HT-29 colon cancer cells. Molecular and Cellular Endocrinology 2001;183:141–9. Lahm H, Amstad P, Wyniger J, Yilmaz A, Fischer JR, Schreyer M, et al. Blockade of the insulin-like growth-factor-I receptor inhibits growth of human colorectal cancer cells: evidence of a functional

M. Di Rosa et al. / Critical Reviews in Oncology/Hematology 88 (2013) 594–612

[48]

[49]

[50]

[51]

[52]

[53]

[54] [55]

[56]

[57]

[58]

[59]

[60]

[61]

[62]

[63]

[64] [65]

IGF-II-mediated autocrine loop. International Journal of Cancer 1994;58:452–9. Polly P, Herdick M, Moehren U, Baniahmad A, Heinzel T, Carlberg C. VDR-Alien: a novel, DNA-selective vitamin D(3) receptorcorepressor partnership. FASEB Journal 2000;14:1455–63. Yanagisawa J, Yanagi Y, Masuhiro Y, Suzawa M, Watanabe M, Kashiwagi K, et al. Convergence of transforming growth factor-beta and vitamin D signaling pathways on SMAD transcriptional coactivators. Science 1999;283:1317–21. Chen A, Davis BH, Sitrin MD, Brasitus TA, Bissonnette M. Transforming growth factor-␤1 signaling contributes to CaCo-2 cell growth inhibition induced by 1,25(OH)2 D3 . American Journal of Physiology – Gastrointestinal and Liver Physiology 2002;283:G864–74. Manning AM, Williams AC, Game SM, Paraskeva C. Differential sensitivity of human colonic adenoma and carcinoma cells to transforming growth factor ␤ (TGF-␤): conversion of an adenoma cell line to a tumorigenic phenotype is accompanied by a reduced response to the inhibitory effects of TGF-␤. Oncogene 1991;6:1471–6. Kouchi Z, Fujiwara Y, Yamaguchi H, Nakamura Y, Fukami K. Phosphatidylinositol 5-phosphate 4-kinase type II beta is required for vitamin D receptor-dependent E-cadherin expression in SW480 cells. Biochemical and Biophysical Research Communications 2011;408:523–9. Gaschott T, Steinmeyer A, Steinhilber D, Stein J. ZK 156718, a low calcemic, antiproliferative, and prodifferentiating vitamin D analog. Biochemical and Biophysical Research Communications 2002;290:504–9. Harris DM, Go VL. Vitamin D and colon carcinogenesis. Journal of Nutrition 2004;134(December (12 Suppl.)):3463S–71S. Díaz GD, Paraskeva C, Thomas MG, Binderup L, Hague A. Apoptosis is induced by the active metabolite of vitamin D3 and its analogue EB1089 in colorectal adenoma and carcinoma cells: possible implications for prevention and therapy. Cancer Research 2000;60: 2304–12. Barnes JD, Arhel NJ, Lee SS, Sharp A, Al-Okail M, Packham G, et al. Nuclear BAG-1 expression inhibits apoptosis in colorectal adenomaderived epithelial cells. Apoptosis 2005;10:301–11. Stambolsky P, Tabach Y, Fontemaggi G, Weisz L, Maor-Aloni R, Siegfried Z, et al. Modulation of the vitamin D3 response by cancerassociated mutant p53. Cancer Cell 2010;17:273–85. Gündüz M, Cacına C, Toptas¸ B, Yaylım-Eraltan ˙I, Tekand Y, ˙Isbir T. Association of vitamin D receptor gene polymorphisms with colon cancer. Genetic Testing and Molecular Biomarkers 2012;16: 1058–61. Bai YH, Lu H, Hong D, Lin CC, Yu Z, Chen BC. Vitamin D receptor gene polymorphisms and colorectal cancer risk: a systematic metaanalysis. World Journal of Gastroenterology 2012;18:1672–9. Larriba MJ, Bonilla F, Mu˜noz A. The transcription factors Snail1 and Snail2 repress vitamin D receptor during colon cancer progression. Journal of Steroid Biochemistry and Molecular Biology 2010;121:106–9. Kallay E, Pietschmann P, Toyokuni S, Bajna E, Hahn P, Mazzucco K, et al. Characterization of a vitamin D receptor knockout mouse as a model of colorectal hyperproliferation and DNA damage. Carcinogenesis 2001;22:1429–35. Höbaus J, Fetahu IS, Khorchide M, Manhardt T, Kallay E. Epigenetic regulation of the 1,25-dihydroxyvitamin D(3) 24-hydroxylase (CYP24A1) in colon cancer cells. Journal of Steroid Biochemistry and Molecular Biology 2012;(August). Pálmer HG, Larriba MJ, García JM, Ordó˜nez-Morán P, Pe˜na C, Peiró S, et al. The transcription factor SNAIL represses vitamin D receptor expression and responsiveness in human colon cancer. Nature Medicine 2004;10:917–9. Kalluri R, Weinberg RA. The basics of epithelial-mesenchymal transition. Journal of Clinical Investigation 2009;119:1420–8. De Craene B, Gilbert B, Stove C, Bruyneel E, van Roy F, Berx G. The transcription factor SNAIL induces tumor cell invasion through

[66]

[67]

[68]

[69]

[70]

[71]

[72]

[73]

[74]

[75]

[76]

[77]

[78]

[79]

[80]

[81]

[82]

[83]

609

modulation of the epithelial cell differentiation program. Cancer Research 2005;65:6237–44. Larriba MJ, Valle N, Pálmer HG, Ordó˜nez-Morán P, Alvarez-Díaz S, Becker KF, et al. The inhibition of Wnt/beta-catenin signalling by 1alpha, 25-dihydroxyvitamin D3 is abrogated by Snail1 in human colon cancer cells. Endocrine-Related Cancer 2007;14:141–51. Pe˜na C, García JM, García V, Silva J, Domínguez G, Rodríguez R, et al. The expression levels of the transcriptional regulators p300 and CtBP modulate the correlations between SNAIL, ZEB1, E-cadherin and vitamin D receptor in human colon carcinomas. International Journal of Cancer 2006;119:2098–104. Larriba MJ, Martín-Villar E, García JM, Pereira F, Pe˜na C, de Herreros AG, et al. Snail2 cooperates with Snail1 in the repression of vitamin D receptor in colon cancer. Carcinogenesis 2009;30:1459–68. Pe˜na C, García JM, Larriba MJ, Barderas R, Gómez I, Herrera M, et al. SNAI1 expression in colon cancer related with CDH1 and VDR downregulation in normal adjacent tissue. Oncogene 2009;28:4375–85. Larriba MJ, Mu˜noz A. SNAIL vs. vitamin D receptor expression in colon cancer: therapeutics implications. British Journal of Cancer 2005;92:985–9. De Craene B, van Roy F, Berx G. Unraveling signalling cascades for the SNAIL family of transcription factors. Cell Signalling 2005;17:535–7. Bises G, Kállay E, Weiland T, Wrba F, Wenzl E, Bonner E, et al. 25Hydroxyvitamin D3-1alpha-hydroxylase expression in normal and malignant human colon. Journal of Histochemistry & Cytochemistry 2004;52:985–9. Kim MS, Fujiki R, Kitagawa H, Kato S. 1alpha, 25(OH)2D3-induced DNA methylation suppresses the human CYP27B1 gene. Molecular and Cellular Endocrinology 2007;265-266:168–73. Dong LM, Ulrich CM, Hsu L, Duggan DJ, Benitez DS, White E, et al. Vitamin D related genes. CYP24A1 and CYP27B1, and colon cancer risk. Cancer Epidemiology, Biomarkers & Prevention 2009;18:2540–8. Horváth HC, Khabir Z, Nittke T, Gruber S, Speer G, Manhardt T, et al. CYP24A1 splice variants – implications for the antitumorigenic actions of 1,25-(OH)2D3 in colorectal cancer. Journal of Steroid Biochemistry and Molecular Biology 2010;121:76–9. Norman AW. 1␣,25(OH) 2 – Vitamin D3mediated rapid and genomic responses are dependent upon critical structure function relationships for both the ligand and receptor(s). In: Feldman D, Pike JW, Glorieux FH, editors. Vitamin D. Burlington: Elsevier Academic Press; 2005. p. 381–7. Wood RJ, Tchack L, Angelo G, Pratt RE, Sonna LA. DNA microarray analysis of vitamin D-induced gene expression in a human colon carcinoma cell line. Physiological Genomics 2004;17:122–9. Sitrin MD, Bissonnette M, Bolt MJ, Wali R, Khare S, ScaglioneSewell B. Rapid effects of 1,25(OH)2 vitamin D3 on signal transduction systems in colonic cells. Steroids 1999;64:137–42. Aubin JE, Heersche JNM. Vitamin D and osteoclast. In: Feldman D, Pike JW, Glorieux FH, editors. Vitamin D. Burlington: Elsevier Academic Press; 2005. p. 649–63. Ordó˜nez-Morán P, Alvarez-Díaz S, Valle N, Larriba MJ, Bonilla F, Mu˜noz A. The effects of 1,25-dihydroxyvitamin D3 on colon cancer cells depend on RhoA-ROCK-p38MAPK-MSK signaling. Journal of Steroid Biochemistry and Molecular Biology 2010;121:355–61. Pálmer HG, González-Sancho JM, Espada J, Berciano MT, Puig I, Baulida J, et al. Vitamin D(3) promotes the differentiation of colon carcinoma cells by the induction of E-cadherin and the inhibition of beta-catenin signaling. Journal of Cell Biology 2001;154: 369–87. Kim S, Shevde NK, Pike JW. 1,25-Dihydroxyvitamin D3 stimulates cyclic vitamin D receptor/retinoid X receptor DNA-binding, co-activator recruitment, and histone acetylation in intact osteoblasts. Journal of Bone and Mineral Research 2005;20:305–17. Chang PL, Lee TF, Garretson K, Prince CW. Calcitriol enhancement of TPA-induced tumorigenic transformation is mediated through

610

[84]

[85]

[86]

[87]

[88] [89]

[90]

[91]

[92] [93]

[94]

[95]

[96]

[97]

[98]

[99]

[100]

[101]

[102]

M. Di Rosa et al. / Critical Reviews in Oncology/Hematology 88 (2013) 594–612 vitamin D receptor-dependent and -independent pathways. Clinical and Experimental Metastasis 1997;15:580–92. Kurisetty VV, Johnston PG, Johnston N, Erwin P, Crowe P, Fernig DG, et al. RAN GTPase is an effector of the invasive/metastatic phenotype induced by osteopontin. Oncogene 2008;27:7139–49. Barletta F, Freedman LP, Christakos S. Enhancement of VDRmediated transcription by phosphorylation: correlation with increased interaction between the VDR and DRIP205, a subunit of the VDRinteracting protein coactivator complex. Molecular Endocrinology 2002;16:301–14. Xu H, McCann M, Zhang Z, Posner GH, Bingham V, El-Tanani M, et al. Vitamin D receptor modulates the neoplastic phenotype through antagonistic growth regulatory signals. Molecular Carcinogenesis 2009;48:758–72. Nemere I. 24,25-Dihydroxyvitamin D3 suppresses the rapid actions of 1,25-dihydroxyvitamin D3 and parathyroid hormone on calcium transport in chick intestine. Journal of Bone and Mineral Research 1999;14:1543–9. Gumbiner BM. Cell adhesion: the molecular basis of tissue architecture and morphogenesis. Cell 1996;84:345–57. Bezdekova M, Brychtova S, Sedlakova E, Langova K, Brychta T, Belej K. Analysis of snail-1, e-cadherin and claudin-1 expression in colorectal adenomas and carcinomas. International Journal of Molecular Sciences 2012;13:1632–43. Shah S, Islam MN, Dakshanamurthy S, Rizvi I, Rao M, Herrell R, et al. The molecular basis of vitamin D receptor and beta-catenin crossregulation. Molecular Cell 2006;21:799–809. Billin AN, Thirlwell H, Ayer DE. Beta-catenin-histone deacetylase interactions regulate the transition of LEF1 from a transcriptional repressor to an activator. Molecular and Cellular Biology 2000;20:6882–90. Watson AJ. An overview of apoptosis and the prevention of colorectal cancer. Critical Reviews in Oncology/Hematology 2006;57:107–21. Halvey PJ, Zhang B, Coffey RJ, Liebler DC, Slebos RJ. Proteomic consequences of a single gene mutation in a colorectal cancer model. Journal of Proteome Research 2012;11:1184–95. Beildeck ME, Islam M, Shah S, Welsh J, Byers SW. Control of TCF-4 expression by VDR and vitamin D in the mouse mammary gland and colorectal cancer cell lines. PLoS ONE 2009;4:e7872. El-Tanani MK, Barraclough R, Wilkinson MC, Rudland PS. Regulatory region of metastasis-inducing DNA is the binding site for T cell factor-4. Oncogene 2001;20:1793–7. Gottardi CJ, Wong E, Gumbiner BM. E-cadherin suppresses cellular transformation by inhibiting beta-catenin signaling in an adhesionindependent manner. Journal of Cell Biology 2001;153:1049–60. Tuck AB, Arsenault DM, O’Malley FP, Hota C, Ling MC, Wilson SM, et al. Osteopontin induces increased invasiveness and plasminogen activator expression of human mammary epithelial cells. Oncogene 1999;18:4237–46. Song S, Mazurek N, Liu C, Sun Y, Ding QQ, Liu K, et al. Galectin3 mediates nuclear beta-catenin accumulation and Wnt signaling in human colon cancer cells by regulation of glycogen synthase kinase3beta activity. Cancer Research 2009;69:1343–9. Roberts DM, Pronobis MI, Poulton JS, Waldmann JD, Stephenson EM, Hanna S, et al. Deconstructing the ␤catenin destruction complex: mechanistic roles for the tumor suppressor APC in regulating Wnt signaling. Molecular Biology of the Cell 2011;22: 1845–63. Wong NA, Pignatelli M. Beta-catenin – a linchpin in colorectal carcinogenesis? The American Journal of Pathology 2002;160(February (2)):389–401. Kawasoe T, Furukawa Y, Daigo Y, Nishiwaki T, Ishiguro H, Fujita M, et al. Isolation and characterization of a novel human gene, DRCTNNB1A, the expression of which is down-regulated by betacatenin. Cancer Research 2000;60:3354–8. Cohen SM, Chastain 2nd PD, Rosson GB, Groh BS, Weissman BE, Kaufman DG, et al. BRG1 co-localizes with DNA replication

[103]

[104]

[105]

[106]

[107] [108]

[109]

[110]

[111]

[112]

[113]

[114] [115]

[116] [117]

[118] [119]

[120] [121]

factors and is required for efficient replication fork progression. Nucleic Acids Research 2010;38:6906–19. González-Sancho JM, Aguilera O, García JM, Pendás-Franco N, Pe˜na C, Cal S, et al. The Wnt antagonist DICKKOPF-1 gene is a downstream target of beta-catenin/TCF and is downregulated in human colon cancer. Oncogene 2005;24(February (6)):1098–103. Aguilera O, Fraga MF, Ballestar E, Paz MF, Herranz M, Espada J, et al. Epigenetic inactivation of the Wnt antagonist DICKKOPF-1 (DKK-1) gene in human colorectal cancer. Oncogene 2006;25:4116–21. Aguilera O, Pe˜na C, García JM, Larriba MJ, Ordó˜nez-Morán P, Navarro D, et al. The Wnt antagonist DICKKOPF-1 gene is induced by 1alpha, 25-dihydroxyvitamin D3 associated to the differentiation of human colon cancer cells. Carcinogenesis 2007;28(September (9)):1877–84. Pendás-Franco N, García JM, Pe˜na C, Valle N, Pálmer HG, Heinäniemi M, et al. DICKKOPF-4 is induced by TCF/beta-catenin and upregulated in human colon cancer, promotes tumour cell invasion and angiogenesis and is repressed by 1alpha, 25-dihydroxyvitamin D3. Oncogene 2008;27:4467–77. Mao B, Niehrs C. Kremen2 modulates Dickkopf2 activity during Wnt/LRP6 signaling. Gene 2003;302:179–83. You J, Nguyen AV, Albers CG, Lin F, Holcombe RF. Wnt pathwayrelated gene expression in inflammatory bowel disease. Digestive Diseases and Sciences 2008;53(April (4)):1013–9. Sato H, Suzuki H, Toyota M, Nojima M, Maruyama R, Sasaki S, et al. Frequent epigenetic inactivation of DICKKOPF family genes in human gastrointestinal tumors. Carcinogenesis 2007;28:2459–66. Bazzi H, Fantauzzo KA, Richardson GD, Jahoda CA, Christiano AM. The Wnt inhibitor, Dickkopf 4, is induced by canonical Wnt signaling during ectodermal appendage morphogenesis. Developmental Biology 2007;305:498–507. Zitt M, Untergasser G, Amberger A, Moser P, Stadlmann S, Zitt M, et al. Dickkopf-3 as a new potential marker for neoangiogenesis in colorectal cancer: expression in cancer tissue and adjacent non-cancerous tissue. Disease Markers 2008;24:101–9. Yu J, Tao Q, Cheng YY, Lee KY, Ng SS, Cheung KF, et al. Promoter methylation of the Wnt/beta-catenin signaling antagonist Dkk-3 is associated with poor survival in gastric cancer. Cancer 2009;115:49–60. Karin M, Gallagher E. From JNK to pay dirt: jun kinases, their biochemistry, physiology and clinical importance. IUBMB Life 2005;57:283–95. Shaulian E, Karin M. AP-1 as a regulator of cell life and death. Nature Cell Biology 2002;4:E131–6. Buitrago CG, Ronda AC, de Boland AR, Boland R. MAP kinases p38 and JNK are activated by the steroid hormone 1alpha, 25(OH)2vitamin D3 in the C2C12 muscle cell line. Journal of Cellular Biochemistry 2006;97:698–708. Ward Y, Kelly K. Gem protein signaling and regulation. Methods in Enzymology 2006;407:468–83. Meyers MB, Schneider KA, Spengler BA, Chang TD, Biedler JL. Sorcin (V19), a soluble acidic calcium-binding protein overproduced in multidrug-resistant cells. Identification of the protein by anti-sorcin antibody. Biochemical Pharmacology 1987;36: 2373–80. Wissenbach U, Niemeyer BA. TRPV6. Handbook of Experimental Pharmacology 2007:221–34, 179. Meyer MB, Watanuki M, Kim S, Shevde NK, Pike JW. The human transient receptor potential vanilloid type 6 distal promoter contains multiple vitamin D receptor binding sites that mediate activation by 1,25-dihydroxyvitamin D3 in intestinal cells. Molecular Endocrinology 2006;20:1447–61. Blyth K, Cameron ER, Neil JC. The RUNX genes: gain or loss of function in cancer. Nature Reviews Cancer 2005;5:376–87. Bangsow C, Rubins N, Glusman G, Bernstein Y, Negreanu V, Goldenberg D, et al. The RUNX3 gene – sequence, structure and regulated expression. Gene 2001;279:221–32.

M. Di Rosa et al. / Critical Reviews in Oncology/Hematology 88 (2013) 594–612 [122] Coffman JA. Runx transcription factors and the developmental balance between cell proliferation and differentiation. Cell Biology International 2003;27:315–24. [123] Cameron ER, Blyth K, Hanlon L, Kilbey A, Mackay N, Stewart M, et al. The Runx genes as dominant oncogenes. Blood Cells, Molecules and Diseases 2003;30:194–200. [124] Marcellini S, Bruna C, Henríquez JP, Albistur M, Reyes AE, Barriga EH, et al. Evolution of the interaction between Runx2 and VDR, two transcription factors involved in osteoblastogenesis. BMC Evolutionary Biology 2010;10:78. [125] Underwood KF, D’Souza DR, Mochin-Peters M, Pierce AD, Kommineni S, Choe M, et al. Regulation of RUNX2 transcription factor-DNA interactions and cell proliferation by vitamin D3 (cholecalciferol) prohormone activity. Journal of Bone and Mineral Research 2012;27:913–25. [126] Emami N, Diamandis EP. New insights into the functional mechanisms and clinical applications of the kallikrein-related peptidase family. Molecular Oncology 2007;1:269–87. [127] Borgo˜no CA, Michael IP, Shaw JL, Luo LY, Ghosh MC, Soosaipillai A, et al. Expression and functional characterization of the cancer-related serine protease, human tissue kallikrein 14. Journal of Biological Chemistry 2007;282:2405–22. [128] Lin R, Nagai Y, Sladek R, Bastien Y, Ho J, Petrecca K, et al. Expression profiling in squamous carcinoma cells reveals pleiotropic effects of vitamin D3 analog EB1089 signaling on cell proliferation, differentiation, and immune system regulation. Molecular Endocrinology 2002;16:1243–56. [129] Kutuzova GD, De Luca HF. 1,25-Dihydroxyvitamin D3 regulates genes responsible for detoxification in intestine. Toxicology and Applied Pharmacology 2007;218:37–44. [130] Hashizume T, Xu Y, Mohutsky MA, Alberts J, Hadden C, Kalhorn TF, et al. Identification of human UDP-glucuronosyltransferases catalyzing hepatic 1alpha, 25-dihydroxyvitamin D3 conjugation. Biochemical Pharmacology 2008;75:1240–50. [131] Alvarez-Díaz S, Valle N, García JM, Pe˜na C, Freije JM, Quesada V, et al. Cystatin D is a candidate tumor suppressor gene induced by vitamin D in human colon cancer cells. Journal of Clinical Investigation 2009;119:2343–58. [132] Cabrita MA, Christofori G. Sprouty proteins, masterminds of receptor tyrosine kinase signaling. Angiogenesis 2008;11: 53–62. [133] Barbáchano A, Ordó˜nez-Morán P, García JM, Sánchez A, Pereira F, Larriba MJ, et al. SPROUTY-2 and E-cadherin regulate reciprocally and dictate colon cancer cell tumourigenicity. Oncogene 2010;29:4800–13. [134] Agger K, Cloos PA, Rudkjaer L, Williams K, Andersen G, Christensen J, et al. The H3K27me3 demethylase JMJD3 contributes to the activation of the INK4A-ARF locus in response to oncogeneand stress-induced senescence. Genes & Development 2009;23: 1171–6. [135] Pereira F, Barbáchano A, Silva J, Bonilla F, Campbell MJ, Mu˜noz A, et al. KDM6B/JMJD3 histone demethylase is induced by vitamin D and modulates its effects in colon cancer cells. Human Molecular Genetics 2011;20:4655–65. [136] Alvarez-Díaz S, Valle N, Ferrer-Mayorga G, Lombardía L, Herrera M, Domínguez O, et al. MicroRNA-22 is induced by vitamin D and contributes to its antiproliferative, antimigratory and gene regulatory effects in colon cancer cells. Human Molecular Genetics 2012;21:2157–65. [137] Meyer MB, Goetsch PD, Pike JW. VDR/RXR and TCF4/␤-catenin cistromes in colonic cells of colorectal tumor origin: impact on c-FOS and c-MYC gene expression. Molecular Endocrinology 2012;26:37–51. [138] Méchin MC, Coudane F, Adoue V, Arnaud J, Duplan H, Charveron M, et al. Deimination is regulated at multiple levels including auto-deimination of peptidylarginine deiminases. Cellular and Molecular Life Sciences 2010;67:1491–503.

611

[139] Cristobo I, Larriba MJ, de los Ríos V, García F, Mu˜noz A, Casal JI. Proteomic analysis of 1␣,25-dihydroxyvitamin D3 action on human colon cancer cells reveals a link to splicing regulation. Journal of Proteomics 2011;75:384–97. [140] Niv Y, Sperber AD, Figer A, Igael D, Shany S, Fraser G, et al. In colorectal carcinoma patients, serum vitamin D levels vary according to stage of the carcinoma. Cancer 1999;86:391–7. [141] Ahearn TU, McCullough ML, Flanders WD, Long Q, Sidelnikov E, Fedirko V, et al. A randomized clinical trial of the effects of supplemental calcium and vitamin D3 on markers of their metabolism in normal mucosa of colorectal adenoma patients. Cancer Research 2011;71:413–23. [142] Fedirko V, Bostick RM, Flanders WD, Long Q, Shaukat A, Rutherford RE, et al. Effects of vitamin D and calcium supplementation on markers of apoptosis in normal colon mucosa: a randomized, doubleblind, placebo-controlled clinical trial. Cancer Prevention Research (Phila) 2009:213–23. [143] Wactawski-Wende J, Kotchen JM, Anderson GL, Assaf AR, Brunner RL, O’Sullivan MJ, et al. Calcium plus vitamin D supplementation and the risk of colorectal cancer. New England Journal of Medicine 2006;354:684–96. [144] Lappe JM, Travers-Gustafson D, Davies KM, Recker RR, Heaney RP. Vitamin D and calcium supplementation reduces cancer risk: results of a randomized trial. American Journal of Clinical Nutrition 2007;85:1586–91. [145] Trivedi DP, Doll R, Khaw KT. Effect of four monthly oral vitamin D3 (cholecalciferol) supplementation on fractures and mortality in men and women living in the community: randomised double blind controlled trial. British Medical Journal 2003;326:469–72. [146] Ding EL, Mehta S, Fawzi WW, Giovannucci EL. Interaction of estrogen therapy with calcium and vitamin D supplementation on colorectal cancer risk: reanalysis of Women’s Health Initiative randomized trial. International Journal of Cancer 2008;122:1690–4. [147] Thomas MG. Luminal and humoral influences on human rectal epithelial cytokinetics. Annals of the Royal College of Surgeons of England 1995;77:85–9. [148] Spina C, Tangpricha V, Yao M, Zhou W, Wolfe MM, Maehr H, et al. Colon cancer and solar ultraviolet B radiation and prevention and treatment of colon cancer in mice with vitamin D and its Gemini analogs. Journal of Steroid Biochemistry and Molecular Biology 2005;97:111–20. [149] Berger AC, Sigurdson ER, LeVoyer T, Hanlon A, Mayer RJ, Macdonald JS, et al. Colon cancer survival is associated with decreasing ratio of metastatic to examined lymph nodes. Journal of Clinical Oncology 2005;23:8706–12. [150] Chu E. An update on the current and emerging targeted agents in metastatic colorectal cancer. Clinical Colorectal Cancer 2012;11:1–13. [151] Gaschott T, Werz O, Steinmeyer A, Steinhilber D, Stein J. Butyrateinduced differentiation of Caco-2 cells is mediated by vitamin D receptor. Biochemical and Biophysical Research Communications 2001;288:690–6. [152] Gonzalez-Angulo AM, Hennessy BT, Mills GB. Future of personalized medicine in oncology: a systems biology approach. Journal of Clinical Oncology 2010;28:2777–83.

Biographies Michelino Di Rosa, Ph.D., is currently assistant researcher in Immunology and Pathology. He was graduated in molecular biology. He was postdoctoral at the Sbarro Institute Cancer Research and Molecular Medicine, Philadelphia, USA. He acquired a post-doctoral experience in the Division of Infectious Diseases, Department of Clinical and Molecular

612

M. Di Rosa et al. / Critical Reviews in Oncology/Hematology 88 (2013) 594–612

Biomedicine, University of Catania. At the present, he is the scientific coordinator of several specific multicenter studies concerning the molecular mechanism involved in cancer and degenerative diseases. Michele Malaguarnera, M.D., is studying the molecular mechanism involved in cancerogenesis and immune-diseases at the Clinical Pathology School of Catania University. Antonio Zanghì graduated in Medicine and Surgery in 1986 – University of Catania. Ph.D. in Surgical Physiopathology in 1989. Specialized in General Surgery in 1994. He attended post-graduate courses at the University of Pisa and “Policlinico Agostino Gemelli” Cattolica University. At the present, he is Associate Professor of Surgery at the Department of Surgery, University of Catania. Teaching assignments in General Surgery and Thoracic Surgery schools. Author of several monograph and book chapters. Attendance at over 100 scientific events (congresses, conferences, seminars, etc.), as speaker.

Antonino Passaniti, Ph.D., is Associate Professor at University of Maryland School of Medicine. Current main research interest is focused on determining the mechanisms regulating endothelial cells proliferation, survival, and differentiation (which may promote angiogenesis), and on exploiting these mechanisms for therapeutic benefit. Lucia Malaguarnera, M.D., Ph.D., is currently Associated Professor of General Pathology at Catania University, School of Medicine. Dr. Malaguarnera was a postdoctoral fellow at the Thomas Jefferson Cancer Institute, Philadelphia, USA, where she studied the regulation of normal hematopoiesis and the mechanisms of abnormal growth in leukemic cells. She then pursued one’s studies at New York Medical College, Department of Pharmacology, Valhalla, New York. Dr. Malaguarnera has extensive research experience in the study of the mechanisms involved in cancerogenesis. Her research interests include the molecular mechanisms involved in degenerative diseases and immune-regulation.