Matrix Metalloproteinases and Their Inhibitors in Gestational Trophoblastic Diseases and Normal Placenta

Matrix Metalloproteinases and Their Inhibitors in Gestational Trophoblastic Diseases and Normal Placenta

Gynecologic Oncology 75, 248 –253 (1999) Article ID gyno.1999.5564, available online at http://www.idealibrary.com on Matrix Metalloproteinases and T...

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Gynecologic Oncology 75, 248 –253 (1999) Article ID gyno.1999.5564, available online at http://www.idealibrary.com on

Matrix Metalloproteinases and Their Inhibitors in Gestational Trophoblastic Diseases and Normal Placenta Gyorgy L. Vegh, M.D.,* Z. Selcuk Tuncer, M.D.,† Vilmos Fulop, M.D.,* David R. Genest, M.D.,‡ Samuel C. Mok, Ph.D.,† and Ross S. Berkowitz, M.D.† †Laboratory of Gynecologic Oncology, Division of Gynecologic Oncology, Department of Obstetrics, Gynecology, and Reproductive Biology, ‡Division of Women’s and Perinatal Pathology, Department of Pathology, New England Trophoblastic Disease Center, Gillette Center for Women’s Cancer, Brigham and Women’s Hospital, Dana Farber Cancer Institute, Harvard Medical School, Boston, Massachusetts 02115; and *Department Obstetrics and Gynecology, Haynal Imre University of Health Sciences, Budapest, Hungary Received April 28, 1999

INTRODUCTION

Objective. Our purpose was to investigate the expression of matrix metalloproteinases (MMPs) in gestational trophoblastic diseases and normal first-trimester placenta. Methods. Paraffin sections of 16 partial moles, 25 complete moles, 10 gestational choriocarcinomas, and 11 normal first-trimester placentas were studied immunohistochemically for expression of MMP-1, MMP-2, MMP-3, MMP-9, MMP-13, and tissue inhibitor of metalloproteinase-1 (TIMP-1). Results. Nine (90.0%) of the choriocarcinoma cases showed strong intensity of staining for MMP-1. Choriocarcinoma exhibited significantly stronger staining for MMP-1 than syncytiotrophoblast in normal placenta (P < 0.01), partial mole (P < 0.01), and complete mole (P < 0.01). Choriocarcinoma also showed significantly stronger staining for MMP-1 than the extravillous trophoblast in placenta (P < 0.05). MMP-2 was expressed only in syncytio- and extravillous trophoblasts in normal placenta, partial mole, and complete mole. Choriocarcinoma and the extravillous trophoblast in partial mole and complete mole had significantly stronger staining for MMP-2 than the extravillous trophoblast in placenta (P < 0.05, P < 0.01, P < 0.01, respectively). Choriocarcinoma also exhibited significantly stronger staining for MMP-2 than syncytiotrophoblasts in placenta (P < 0.01), partial mole (P 5 0.05), and complete mole (P < 0.01). The expression of MMP-3, MMP-9, and MMP-13 was similar in all four tissues with the predominance of syncytiotrophoblast for MMP-3 and MMP-13 and cytotrophoblast for MMP-9. While 8 (73.0%) placentas, 14 (87.5%) partial moles, and 19 (76.0%) complete moles showed strong immunoreactivity for TIMP-1 in syncytiotrophoblasts, no strong staining was found in choriocarcinomas (P < 0.01, P < 0.01, P < 0.01, respectively). Conclusion. The extravillous trophoblast of first-trimester placenta has significantly less expression of MMP-1 than choriocarcinoma and significantly less expression of MMP-2 than choriocarcinoma and extravillous trophoblast of partial and complete mole. The expression of TIMP-1 was significantly less in choriocarcinoma than the syncytiotrophoblast of normal placenta, partial mole, and complete mole. MMPs and their inhibitors may play a role in the pathogenesis of gestational trophoblastic diseases. © 1999 Academic Press Key Words: MMP; TIMP; trophoblastic disease; placenta. 0090-8258/99 $30.00 Copyright © 1999 by Academic Press All rights of reproduction in any form reserved.

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Gestational trophoblastic diseases comprise a spectrum of chorionic diseases that include partial and complete hydatidiform moles and gestational choriocarcinoma [1]. These tumors have varying propensities for local uterine invasion and spread and can be highly cured even in the presence of widespread metastases [2, 3]. Placental tissue contains a heterogeneous population of cells, including villous syncytiotrophoblast and cytotrophoblast, as well as extravillous trophoblast. Whereas villous trophoblast does not exhibit invasive behavior, the invasive capacity of the extravillous trophoblast appears to have similarities with the role of malignant cells during tumor invasion [4, 5]. However, trophoblast invasion of the endometrium is tightly regulated during the first trimester of normal pregnancy [4]. Extravillous trophoblast cells migrate from the basement membrane of anchoring villi and invade deeply, reaching the myometrium. The process of trophoblast invasion involves the enzymatic degradation of the extracellular matrix [6, 7]. Different families of matrix-degrading proteases have been found to be involved in trophoblastic invasion into the maternal tissues, including serine proteases and matrix metalloproteinases (MMPs) [6 – 8]. MMPs are a family of zinc-containing endopeptidases that degrade a wide range of components of the extracellular matrix; MMPs are also thought to play an important role in tumor progression and metastasis [5– 8]. To date at least 20 members of the MMP family have been reported and divided into four main groups according to their substrate specificities: collagenases, gelatinases, stromelysins, and membrane-type MMPs [9, 10]. All MMPs are secreted in inactive form. The activity of the MMPs is regulated by several biological modulators including tissue inhibitors of metalloproteinases (TIMPs). These secreted inhibitory proteins bind the active forms of MMPs and inhibit their individual proteolytic activity in tissue [9, 11, 12]. The potential interactions amongst MMPs are currently under active investigation and the specific

MATRIX METALLOPROTEINASES AND TROPHOBLASTIC DISEASES

substrates of MMPs that have been identified are summarized in recent review articles [13, 14]. For example, both MMP-2 and MMP-9 degrade Type IV collagen, which is a major component of the basement membrane and constitutes an important barrier to tumor cell invasion. In contrast, MMP-1 degrades Type II and III collagen. In the present study we investigated the expression of MMPs and TIMP-1 in normal first-trimester placenta, partial and complete mole, and choriocarcinoma by immunohistochemical analysis. We also evaluated whether the expression of MMPs by complete molar pregnancy was associated with the development of postmolar gestational trophoblastic tumor. MATERIALS AND METHODS Collection of Tissues and Clinical Data Archival tissues in paraffin blocks from 62 cases were collected including 16 partial moles, 25 complete moles, 10 gestational choriocarcinomas, and 11 normal first-trimester placentas as control specimens. The slides from all 62 cases were reviewed by one of the authors (DRG), who is a gynecologic pathologist with recognized special interest and expertise in the pathology of gestational trophoblastic disease. The diagnosis of partial and complete mole was made using standard published histopathologic criteria [2, 3]. All placental sections originated from therapeutic abortions of first-trimester normal pregnancies between the gestational age of 8 and 12 weeks (mean gestational age was 9.5 weeks). The mean gestational age was 8.4 weeks for partial and 9.8 weeks for complete mole. Written consent for the collection of tissue samples was obtained according to a protocol approved by the Human Subject Committee of Brigham and Women’s Hospital. All patients were diagnosed and treated at the Department of Obstetrics, Gynecology, and Reproductive Biology, Brigham and Women’s Hospital, Harvard Medical School (Boston, MA). Eight (32.0%) of the patients with complete mole developed persistent postmolar gestational trophoblastic tumor. A total of 11 cycles of chemotherapy were administered to these patients. Of the choriocarcinoma cases, 8 (80.0%) had stage I (World Health Organization Score, mean 2.0, range 1– 4) and 2 (20.0%) had stage III disease (World Health Organization Score—3,8); a total of 28 cycles of chemotherapy were administered to these patients. The follow-up and management protocol for gestational trophoblastic diseases has previously been published from our center and was followed in each case [15, 16]. In brief, patients with nonmetastatic disease (Stage I) and low-risk Stage III disease (pulmonary metastases) were treated with methotrexate and citrovorum factor. The patient with high-risk Stage III disease was treated with primary EMA–CO chemotherapy (etoposide, methotrexate, actinomycin D– cyclophosphamide and Oncovin). All patients achieved complete sustained gonadotropin remission. None of the patients who developed persistent postmolar gestational trophoblastic tumor underwent hysterectomy. Fur-

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thermore, the two patients with choriocarcinoma and pulmonary metastases did not undergo surgical resection of metastases. None of the cases of gestational trophoblastic disease had fresh tissue available for investigation. Immunohistochemical Analysis The avitin– biotin complex peroxidase method was performed on 5-mm-thick sections from formalin-fixed, paraffinembedded tissues. Sections were deparaffinized in xylene and hydrated with graded ethanol concentrations and distilled water. For both MMP-1 and MMP-3, the slides underwent pretreatment boiling in 0.01 M citric acid buffer (pH 6.0) for 15 min. Endogenous peroxidase activity was blocked with 0.3% hydrogen peroxide in methanol for 30 min. After blocking nonspecific antigens with normal horse serum, the sections were incubated overnight at 4°C with primary antibodies in a moist chamber. The primary antibodies in this study (MMP-1, MMP-2, MMP-3, MMP-9, MMP-13, and TIMP-1) were all mouse monoclonal antibodies and were all purchased from Oncogene Research Products (Cambridge, MA). The dilutions that were utilized with these antibodies were as follows: MMP-2, MMP-3, and MMP-13—1:400; MMP-1, MMP-9, and TIMP-1—1:800. The positive control tissues for the primary antibodies were as follows: MMP-1 and MMP-13— breast cancer; MMP-2 and MMP-3— ovarian cancer; MMP-9 —rectal cancer; and TIMP-1—normal ovary. The primary antibody was replaced by normal mouse serum for a negative control. Staining was achieved using a biotinylated antimouse secondary antibody and the ABC horseradish–peroxidase (Vectastain Elite ABC Kit; Vector, Burlingame, CA). The reaction product was visualized by 3,39 diaminobenzidine tetrahydrochloride (Vector) as chromogen. Finally, the sections were dehydrated in ethanol, cleared in xylene, and mounted. In this study 51 gestational trophoblastic disease cases and 11 normal first-trimester placentas were investigated for expression of MMP-1, MMP-2, MMP-3, MMP-9, MMP-13, and their main inhibitor TIMP-1 by immunohistochemistry. Cytoplasmic staining of syncytiotrophoblast, cytotrophoblast, extravillous trophoblast, and trophoblastic tumor cells in choriocarcinoma sections was categorized as negative, weakly positive, or strongly positive. A strongly positive result was recorded when more than 50% of the cells exhibited strong staining. Statistical Analysis The immunohistochemical data and the postevacuation clinical outcome of complete molar cases were analyzed by StatView 4.5 package. x 2 and Fisher’s exact x 2 tests were used. Statistical significance was considered at the 0.05 level. RESULTS Expression of MMP-1 was predominantly strong in cytotrophoblasts and extravillous trophoblasts in normal placenta,

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TABLE 1 Immunostaining of Placentas, Partial Moles, and Complete Moles Placenta (n 5 11)

MMP-1

MMP-2

MMP-3

MMP-9

MMP-13

TIMP-1

ST CT EVT ST CT EVT ST CT EVT ST CT EVT ST CT EVT ST CT EVT

Partial mole (n 5 16)

Complete mole (n 5 25)

Negative (%)

Weak (%)

Strong (%)

Negative (%)

Weak (%)

Strong (%)

Negative (%)

Weak (%)

Strong (%)

— — 1 (9.0) — 11 (100.0) — — 9 (82.0) 5 (45.5) — 1 (9.0) 4 (36.0) — 11 (100.0) 5 (45.0) — — —

11 (100.0) 2 (18.0) 6 (55.0) 11 (100.0) — 9 (82.0) 7 (64.0) 2 (18.0) 5 (45.5) 9 (82.0) 9 (82.0) 5 (45.0) 6 (55.0) — 6 (55.0) 3 (27.0) 11 (100.0) 10 (91.0)

— 9 (82.0) 4 (36.0) — — 2 (18.0) 4 (36.0) — 1 (9.0) 2 (18.0) 1 (18.0) 2 (18.0) 5 (45.0) — — 8 (73.0) — 1 (9.0)

— — — — 16 (100.0) — — 12 (75.0) 4 (25.0) — 1 (6.2) 6 (37.6) — 14 (87.5) 7 (43.8) — 6 (37.5) 2 (12.5)

16 (100.0) 1 (6.2) 6 (37.5) 10 (62.5) — 6 (37.5) 4 (25.0) 4 (25.0) 11 (68.8) 9 (56.2) 8 (50.0) 5 (31.2) 9 (56.2) 2 (12.5) 9 (56.2) 2 (12.5) 10 (62.5) 12 (75.0)

— 15 (93.8) 10 (62.5) 6 (37.5) — 10 (62.5) 12 (75.0) — 1 (6.2) 7 (43.8) 7 (43.8) 5 (31.2) 7 (43.8) — — 14 (87.5) — 2 (12.5)

— — — — 25 (100.0) — — 20 (80.0) 6 (24.0) — — 3 (12.0) — 22 (88.0) 3 (12.0) — 6 (24.0) 6 (24.0)

21 (84.0) 9 (43.8) 10 (40.0) 22 (88.0) — 2 (8.0) 15 (60.0) 5 (20.0) 19 (76.0) 10 (40.0) 14 (56.0) 18 (72.0) 14 (56.0) 3 (12.0) 20 (80.0) 6 (24.0) 19 (76.0) 19 (76.0)

4 (16.0) 16 (56.2) 15 (60.0) 3 (12.0) — 23 (92.0) 10 (40.0) — — 15 (60.0) 11 (44.0) 4 (16.0) 11 (44.0) — 2 (8.0) 19 (76.0) — —

Note. ST, syncytiotrophoblast; CT, cytotrophoblast; EVT, extravillous trophoblast.

partial mole, and complete mole (Table 1). Nine (90.0%) of the choriocarcinoma cases showed strong intensity of staining for MMP-1 (Table 2). Choriocarcinoma exhibited significantly stronger staining for MMP-1 than syncytiotrophoblast in normal placenta (P , 0.01), partial mole (P , 0.01), and complete mole (P , 0.01). Choriocarcinoma also showed significantly stronger staining for MMP-1 than the extravillous trophoblast in placenta (P , 0.05). Strong staining for MMP-1 was observed in cytotrophoblasts in 9 (82.0%) placentas, 15 (93.8%) partial moles, and 16 (56.2%) complete moles (Fig. 1A). MMP-2 was expressed only in syncytio- and extravillous trophoblasts in normal placenta, partial mole, and complete mole. Choriocarcinoma and the extravillous trophoblast in partial mole and complete mole had significantly stronger staining for MMP-2 than the extravillous trophoblast in placenta (P , 0.05, P , 0.01, P , 0.01, respectively). Choriocarcinoma also exhibited significantly stronger staining for MMP-2 than syncytiotrophoblasts in placenta, partial mole, and complete mole (P , 0.01, P 5 0.05, P , 0.01, respectively), (Figs. 1B and 1C). TABLE 2 Immunostaining of Choriocarcinoma Cases (n 5 10) Antibody

Negative (%)

Weak (1) (%)

Strong (1) (%)

MMP-1 MMP-2 MMP-3 MMP-9 MMP-13 TIMP-1

— — 4 (40.0) — — 2 (20.0)

1 (10.0) 2 (20.0) 6 (60.0) 6 (60.0) 8 (80.0) 8 (80.0)

9 (90.0) 8 (80.0) — 4 (40.0) 2 (20.0) —

Strong MMP-3 immunoreactivity was found almost exclusively in syncytiotrophoblasts of placentas (36.0%), partial moles (75.0%), and complete moles (40.0%). Cytotrophoblast, extravillous trophoblast, and choriocarcinoma cells showed mostly weakly positive or negative staining for MMP-3. MMP-9 expression was observed in all three trophoblastic cell types in placenta, partial mole, and complete mole. Syncytiotrophoblast in complete mole had significantly greater expression of MMP-9 than in placenta (P , 0.05). There were no other significant differences in expression of MMP-9 amongst placenta and gestational trophoblastic disease tissues. MMP-13 expression was found to be similar in all four tissues and all trophoblastic cell types. Cytotrophoblast was mainly negative for MMP-13 staining, while syncytiotrophoblasts, extravillous trophoblasts, and tumor cells were mostly weakly positive. Expression of TIMP-1 was found in all three trophoblastic cell types in placenta, partial mole, and complete mole, with predominance of the syncytiotrophoblast. Cytotrophoblasts and extravillous trophoblasts stained weakly in almost all cases. While 8 (73.0%) placentas, 14 (87.5%) partial moles, and 19 (76.0%) complete moles showed strong immunoreactivity for TIMP-1 in syncytiotrophoblasts, no strong staining was found in choriocarcinomas (P , 0.01, P , 0.01, P , 0.01, respectively), (Figs. 1D and 1E). MMPs and TIMP-1 expression in complete moles was compared to the risk of persistent postmolar gestational trophoblastic tumor (Table 3). Strong staining was compared with both weak and negative staining. Expression of MMPs and their inhibitor, TIMP-1, in complete moles was not associated with the development of postmolar gestational trophoblastic tumor.

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FIG. 1. Immunohistochemical analysis of expression of MMP-1, MMP-2, and TIMP-1 in gestational trophoblastic diseases. (A) Strongly positive MMP-1 immunoreactivity in choriocarcinoma cells (magnification: 1003). (B) Strongly positive MMP-2 immunoreactivity in choriocarcinoma cells (magnification: 1003). (C) Strongly positive MMP-2 immunoreactivity in extravillous trophoblasts of complete mole (magnification: 1003). (D) Strongly positive TIMP-1 immunoreactivity in syncytiotrophoblasts in partial mole (magnification: 1003). (E) No immunoreactivity for TIMP-1 in choriocarcinoma cells (magnification: 2003).

DISCUSSION Because matrix metalloproteinases degrade a wide range of components of the extracellular matrix, MMPs have been suggested to play a vital role in tumor invasion and metastasis [17–19]. The expression and activity of MMPs have been investigated in several human malignancies. MMP-1 and MMP-2 have been reported to be overexpressed in a majority of intestinal cancers [11, 20, 21], and MMP-2 has been implicated in the tumorigenicity of prostate, cervical, and endometrial cancers [22–27]. Davidson et al. and Tamakoshi et al. showed strong expression of MMP-2 and MMP-9 in cervical cancer which correlated with tumor invasion and progression [24, 25, 27]. During normal pregnancy, extravillous trophoblasts locally invade maternal tissues and this process of invasion involves enzymatic degradation of the extracellular matrix. MMPs along with other proteases have been reported to be involved in trophoblastic invasion of maternal tissues [4, 6]. The current study was undertaken to investigate the expression of MMPs in gestational trophoblastic diseases including

partial mole, complete mole, and choriocarcinoma. Gestational trophoblastic diseases are well recognized to have varying propensities for local invasion and metastasis [1–3]. Importantly choriocarcinoma exhibited significantly stronger expression for both MMP-1 and MMP-2 than syncytiotrophoblast in normal placenta, partial mole and complete mole, and extravillous trophoblast in placenta. Furthermore the extravillous trophoblast in partial and complete mole had significantly stronger staining for MMP-2 than the extravillous trophoblast in normal placenta. The increased expression of MMP-2 in partial and complete mole compared to normal placenta may contribute to their risk for local myometrial invasion. While choriocarcinoma had significantly increased expression of MMP-1 and MMP-2 compared to placenta, partial mole, and complete mole, choriocarcinoma had significantly less expression of the tissue inhibitor of metalloproteinase-1 than placenta, partial mole, and complete mole. The increased expression of MMP-1 and MMP-2 and decreased expression of TIMP-1 in choriocarcinoma may contribute to the invasiveness of choriocarcinoma cells.

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TABLE 3 Risk of Persistent Postmolar Gestational Disease after Complete Moles MMP-1

ST Spon. remission: n 5 17 Persistent GTD: n 5 8 CT Spon. remission: n 5 17 Persistent GTD: n 5 8 EVT Spon. remission: n 5 17 Persistent GTD: n 5 8

MMP-2

Weak 1

Strong 1

P

Weak 1

Strong 1

P

Weak 1

Strong 1

P

14 7

3 1

NS

15 7

2 1

NS

12 3

5 5

NS

5 4

12 4

NS

— —

— —



17 8

— —



5 5

12 3

NS

1 1

16 7

NS

17 8

— —



MMP-9

ST Spon. remission: n 5 17 Persistent GTD: n 5 8 CT Spon. remission: n 5 17 Persistent GTD: n 5 8 EVT Spon. remission: n 5 17 Persistent GTD: n 5 8

MMP-3

MMP-13

TIMP-1

Weak 1

Strong 1

P

Weak 1

Strong 1

P

Weak 1

Strong 1

P

7 3

10 5

NS

11 3

6 5

NS

4 2

13 6

NS

11 3

6 5

NS

17 8

— —



17 8

— —



14 7

3 1

NS

16 7

1 1

NS

17 8

— —



Note. ST, syncytiotrophoblast; CT, cytotrophoblast; EVT, extravillous trophoblast; GTD, gestational trophoblastic disease.

MMPs and tissue inhibitors may play an important role in the pathogenesis of gestational trophoblastic diseases. Fortunately, gestational trophoblastic tumors are generally remarkably sensitive to chemotherapy and all patients in the current study achieved complete remission. However, infrequently, patients with drug-resistant gestational trophoblastic tumors are encountered and there is a continuing need to develop and evaluate new chemotherapeutic agents. Anti-neoplastic drugs are currently being developed that modify the activity of MMPs and their inhibitors and these agents may exhibit activity against gestational trophoblastic diseases [28, 29]. Further understanding of the role of MMPs in the biology of gestational trophoblastic diseases may therefore lead to new and novel therapies for patients with these diseases. ACKNOWLEDGMENT This research was supported by the United States–Hungarian Science and Technology Joint Fund (No. 552) and the Soros Foundation.

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