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M2009 PI3K Inhibition Suppresses Growth of Inflammation-Mediated Colon Cancer in Mice
AGA Abstracts
our prospective endoscopic cohort study investigating gastric cancer development (Gut 2005;54:764). Among them, the subjects who simultaneously underwent colonoscopy screening were evaluated. A total of 2,724 subjects (male/female = 1,918/806, mean age = 47.6) were entered into analysis. Serum pepsinogen levels (ng/ml) and anti-H. pylori antibody were measured as indicators of chronic gastritis and H. pylori infection. The risk of colorectal adenomas in subjects with duodenal ulcer and gastric ulcer including scar lesions, and H. pylori positive gastritis without ulcers were compared with the other control subjects. Results: Among 2,724 subjects, duodenal ulcer was found in 183 subjects (6.7%), gastric ulcer in 224 subjects (8.2%), including 45 subjects with both ulcers. H. pylori associated gastritis was found in 1204 subjects (44.2%), and the remaining 1158 subjects served as the control. Among the total subjects, colorectal adenomas were found in 452 subjects (16.6%). Pepsinogen I and II levels were 58.3 and 16.0 in the patients with colorectal adenoma, which were slightly higher than those of 56.9 and 15.0 in the subjects without colorectal adenoma (p=0.28 and p=0.045). The prevalence of colorectal adenomas was 14.7% (170/1158) in the control subjects, whereas the prevalence was 16.7% (201/1204, p=0.18 vs the control) in H. pylori associated gastritis, 19.6% (35/179, p=0.09) in gastric ulcer alone, 23.9% (33/ 138, p=0.005) in duodenal ulcer alone, and 28.9% (13/45, p=0.01) in patients with both ulcers. In a multivariate analysis controlling sex and age, duodenal ulcer was shown to be a significant risk factor for colorectal adenoma (adjusted Odds Ratio 1.72, 95%CI 1.2-2.5, p=0.005). Conclusion: Duodenal ulcer was a risk factor for colorectal adenoma. The patients with duodenal ulcer and those with colorectal adenoma might have a common background factors for inflammatory response.
junctions in AOM/DSS-receiving mice, however, MP6-XT22 treatment restored the tight junctions. Conclusions: Our studies suggest that the TNFR2 signaling in intestinal epithelial cells may be directly involved in the development of CAC with persistent colitis, and imply that the maintenance therapy with anti-TNF mAb may prevent the development of CAC in patients with IBD. M2011 Epigenetic Suppression of the Mismatch Repair Protein MLH1 By Hypoxia in Microsatellite Unstable Colon Cancer in Gia2-/- Mice Mavee S. Witherspoon, Kehui Wang, Steven M. Lipkin, Robert A. Edwards Colorectal cancer (CRC) in patients with either IBD or DNA mismatch repair (MMR) defects differs from sporadic colon cancer. IBD-CRC and MMR-defective CRCs are more likely to be right sided, multifocal, mucinous, arise from areas of flat dysplasia, and have microsatellite instability. The Gia2-/- mouse model of IBD-CRC develops cancers that have all of these features. We found that the MMR protein MLH1 is downregulated in inflamed mucosa and cancers, and these tumors contain microsatellite instability and have impaired DNA damage responses. We have therefore investigated mechanisms of MLH1 silencing in colonic mucosa. MLH1 epigenetic silencing via promoter DNA methylation is a well established mechanism of carcinogenesis. We did not observe altered MLH1 promoter methylation in in inflamed Giα2-/- mucosa. Recently, hypoxia has been shown to silence MLH1 expression In Vitro by a mechanism involving histone deacetylation of the proximal promoter. We verified that hypoxic murine colonic epithelial cells (YAMC cells) downregulate MLH1 and have decreased acetylated histone H3 at the proximal MLH1 promoter by chromatin immunoprecipitation. HDAC inhibitor treatment upregulates acetyl-H3 levels and MLH1 expression In Vitro. Using 2-nitroimidazoles as In Vivo markers of hypoxia, we have identified tissue hypoxia in inflamed Giα2-/- mucosa and cancers that have decreased MLH1 (and its obligate binding partner PMS2) by qRT-PCR, immunohistochemistry, and western blot. In Vivo, treating Giα2-/mice with the HDAC inhibitor SAHA increases acetylated histone H3 levels and enhances MLH1 expression in colonic crypts. These data suggest that chronic hypoxic inflammation contributes to MMR- defective colon cancer via epigenetic histone modifications and silencing of the MLH1 locus.
M2009 PI3K Inhibition Suppresses Growth of Inflammation-Mediated Colon Cancer in Mice Takaaki Tsushimi, Hiroshi Saito, B. M. Evers Numerous studies have documented the link between chronic intestinal inflammation and colorectal cancer (CRC). Phosphatidylinositol 3-kinase (PI3K) stimulates the growth and invasion of a number of cancers including CRC. We have shown that wortmannin, a PI3K inhibitor, reduces the growth of human CRC xenografts In Vivo; the effect of PI3K inhibition on CRCs induced by inflammation is not known. The purpose of this study was to determine whether PI3K signaling plays a role in the development of CRC using a murine model of colonic inflammation and tumor development. METHODS. For all studies, male C57BL/6 mice (6-8 wks old) were used. To induce inflammation and tumor formation, mice were treated by a single intraperitoneal (ip) injection of the tumor promoter azoxymethane (AOM; 10 mg/kg) on day 0, followed by 2% dextran sodium sulfate (DSS) in drinking water for 7 days. i) In the first experiment, AOM/DSS-treated and control mice were sacrificed on week 12 and colonic mucosa harvested; activation of PI3K was assessed by Western blot for expression of PI3K downstream effector proteins (phosphorylated Akt, mTOR, p70S6K and 4E-BP1). ii) The experiment was repeated; disease activity index (DAI) was calculated and correlated with tumor formation. iii) Next, the experiment was repeated and mice subdivided to receive wortmannin (0.75 mg/kg, ip) or vehicle (5% EtOH) every 8 h on weeks 4, 6, 8 and 10 for 7 days; mice were sacrificed on week 12. RESULTS. Phosphorylation of Akt, mTOR, p70S6K and 4E-BP1 was significantly increased in the colonic tumors as compared to normal mucosa. Tumor size was significantly correlated with DAI (R = 0.89; p < 0.01). Wortmannin treatment significantly reduced the average size of colonic tumors compared to the vehicle-treated group (14.9 mm2 vs 30.3 mm2, respectively). CONCLUSIONS. PI3K activation is markedly increased in the colonic tumors arising from colonic inflammation. Inhibition of PI3K suppresses the growth of colonic tumors induced by AOM/ DSS suggesting that the PI3K/Akt pathway plays a critical role in inflammation-mediated development of colonic tumors. Inhibition of PI3K may represent a potential preventive therapy for CRCs induced by chronic inflammation.
M2012 Vav1 Acts As An Essential Modulator in Colitis Associated Colon Cancer Stefanie Zenker, Imke Atreya, Christoph Becker, Markus F. Neurath Introduction: The important intracellular adapter molecule and guanine nucleotide exchange factor Vav1 plays key roles in various intracellular signalling cascades. In contrast to the specific characterization of Vav1 in T lymphocytes, the impact of Vav1 in macrophages has not been studied extensively yet. We now analysed the effects of Vav1 deficiency in macrophages and hence the influence and function of Vav1 in the setting of intestinal inflammation and tumorigenesis. Methods: The susceptibility of Vav1 deficient (Vav1-/-) mice was tested in the dextran sulfate sodium (DSS)/azoxymethane (AOM) model of colitis associated colon cancer. Severity of mucosal inflammation and tumour burden was evaluated by miniendoscopy. In Vivo and In Vitro behaviour of Vav1-/-macrophages was further specified by immunhistology, ELISA, real time PCR and Western blotting. Results: Compared to wildtype (WT) Balb/c mice, treatment with DSS/AOM resulted in enhanced susceptibility of Vav1 deficient mice for colonic tumorigenesis. A higher number of colonic tumours and an increased tumour size could be detected in Vav1-/-mice compared to WT Balb/c animals. The evident infiltration of F4/80+macrophages in the inflamed intestinal mucosa of WT balb/c mice as well as of Vav1-/-mice exemplified that this cell population seemed to be very important in our tumour model. Interestingly, the early secretion of pro-inflammatory cytokine IL-6 was significantly enhanced by LPS-stimulated Vav1-/-macrophages In Vitro compared to WT cells. At the same time, secretion of TNF-alpha by macrophages was not markedly affected by the lack of Vav1 in our experimental setting. Furthermore, the lack of Vav1 in macrophages revealed in reduced cDNA- and protein level of SOCS3. These results implicate that active Vav1 is essential for LPS-mediated induction of SOCS3 in macrophages and thereby plays a central role for the regulation of IL-6 secretion. Conclusion: Vav1 exhibits a protective key role in inflammation associated colonic tumour genesis. Overall our results give evidence to the working hypothesis that the tumour-suppressive potential of Vav1 is trigged by its capacity to induce the expression of SOCS3 and thus the down regulation of pro-inflammatory cytokines.
M2010 Tumor Necrosis Factor Receptor Signaling in Intestinal Epithelial Cells May Be Directly Involved in Colitis-Associated Carcinogenesis Michio Onizawa, Takashi Nagaishi, Shigeru Oshima, Ryuichi Okamoto, Teruji Totsuka, Kiichiro Tsuchiya, Takanori Kanai, Hideo Yagita, Mamoru Watanabe Background & Aim: Treatment with anti-tumor necrosis factor (TNF) mAb has been accepted as a successful therapy for patients with inflammatory bowel diseases (IBD). It has been recently reported that blockade of TNF receptor (TNFR) 1 signaling in infiltrating hematopoietic cells may prevents the development of colitis-associated cancer (CAC). However, it remains unclear whether the TNF signaling in the epithelial cells is also involved in the development of CAC. To investigate this, we studied the effects of anti-TNF mAb in animal models of colitis and CAC. Methods & Results: Wild type C57BL/6 (WT B6) mice were treated with 3.0% DSS-contained drinking water for 5 days as acute phase followed by 5 days of recovering phase with regular water and subsequently sacrificed. Western blotting (WB) and immunohistochemistry (IHC) showed that the NF-κB pathway is activated in the colonic epithelia from DSS-treated mice in association with increased expression of TNF in inflamed mucosa. It was also observed that TNFR-2, but not TNFR1, was significantly upregulated in the epithelia from DSS-treated mice by quantitative RT-PCR and WB. Given these results, a mouse colonic epithelial cell line, CT26, was examined whether TNFR2 signaling is associated with NF-κB activation in these cells. Stimulation with recombinant (r) TNF led to NF-κB activation in CT26 cells in a dose dependent fashion, and blockade of TNF with a specific mAb, MP6-XT22, diminished such NF-κB activity. The expression of myosin light chain kinase (MLCK), which has been reported to be a responsible molecule to the permeability of epithelial barrier in colitis, was downregulated in CT26 cells when TNFR2 was silenced by specific siRNA transfection even in the presence of rTNF. We next induced the CAC model by pretreatment with azoxymethane (AOM) in DSS-receiving mice. Mice administered with AOM/DSS revealed multiple tumors in the middle to distal colon and the NF-κB pathway was further activated in association with more upregulated TNFR2 in the tumor compared to non-tumor area. Despite inability to reduce the severity of colitis, sequential MP6-XT22 treatment reduced the numbers and size of tumors in association with the NF-κB inactivation. IHC with anti-ZO-1 pAb showed that the disrupted epithelial tight
AGA Abstracts
M2013 Effect of Targeting the Neurokinin-1 Receptor On the Transition of Chronic Inflammation to Dysplasia Beatriz Pagan, Angel A. Isidro, Domenico Coppola, Jie Wu, Caroline B. Appleyard Patients with long-standing colitis have a significantly increased risk of developing colorectal cancer. Substance P and its neurokinin-1 receptor (NK-1R) are known to be involved in chronic colonic inflammation but their role in the transition to dysplasia is unclear. Aim: To investigate the effects of targeting the NK-1R in a novel model of colitis-associated dysplasia with a selective NK-1R antagonist. Methods: Chronic colitis was induced in male Sprague Dawley rats by the administration of trinitrobenzene sulfonic acid (TNBS; 30 mg in 50% ethanol ic), followed six weeks later by reactivation with TNBS (5 mg/kg iv) for three days. To induce colitis-associated dysplasia the rats then received TNBS (iv) twice a week for ten weeks. One group received the NK-1R antagonist SR140333 (1 mg/kg ip) twice a week for ten weeks; the rest received vehicle (n=22/group). After sacrifice the colons were removed and analyzed for total macroscopic damage, microscopic damage and presence of dysplasia. The expression of the downstream signalling components and cell proliferation were analyzed by immunohistochemical staining and quantitative real-time RT-PCR. Results: Those animals receiving the NK-1R antagonist gained significantly less weight than the vehicle treated group throughout the study, however, these animals had significantly less macroscopic (p<0.01) and microscopic damage (p<0.01) than the vehicle treated-controls.
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our prospective endoscopic cohort study investigating gastric cancer development (Gut 2005;54:764). Among them, the subjects who simultaneously underwent colonoscopy screening were evaluated. A total of 2,724 subjects (male/female = 1,918/806, mean age = 47.6) were entered into analysis. Serum pepsinogen levels (ng/ml) and anti-H. pylori antibody were measured as indicators of chronic gastritis and H. pylori infection. The risk of colorectal adenomas in subjects with duodenal ulcer and gastric ulcer including scar lesions, and H. pylori positive gastritis without ulcers were compared with the other control subjects. Results: Among 2,724 subjects, duodenal ulcer was found in 183 subjects (6.7%), gastric ulcer in 224 subjects (8.2%), including 45 subjects with both ulcers. H. pylori associated gastritis was found in 1204 subjects (44.2%), and the remaining 1158 subjects served as the control. Among the total subjects, colorectal adenomas were found in 452 subjects (16.6%). Pepsinogen I and II levels were 58.3 and 16.0 in the patients with colorectal adenoma, which were slightly higher than those of 56.9 and 15.0 in the subjects without colorectal adenoma (p=0.28 and p=0.045). The prevalence of colorectal adenomas was 14.7% (170/1158) in the control subjects, whereas the prevalence was 16.7% (201/1204, p=0.18 vs the control) in H. pylori associated gastritis, 19.6% (35/179, p=0.09) in gastric ulcer alone, 23.9% (33/ 138, p=0.005) in duodenal ulcer alone, and 28.9% (13/45, p=0.01) in patients with both ulcers. In a multivariate analysis controlling sex and age, duodenal ulcer was shown to be a significant risk factor for colorectal adenoma (adjusted Odds Ratio 1.72, 95%CI 1.2-2.5, p=0.005). Conclusion: Duodenal ulcer was a risk factor for colorectal adenoma. The patients with duodenal ulcer and those with colorectal adenoma might have a common background factors for inflammatory response.
junctions in AOM/DSS-receiving mice, however, MP6-XT22 treatment restored the tight junctions. Conclusions: Our studies suggest that the TNFR2 signaling in intestinal epithelial cells may be directly involved in the development of CAC with persistent colitis, and imply that the maintenance therapy with anti-TNF mAb may prevent the development of CAC in patients with IBD. M2011 Epigenetic Suppression of the Mismatch Repair Protein MLH1 By Hypoxia in Microsatellite Unstable Colon Cancer in Gia2-/- Mice Mavee S. Witherspoon, Kehui Wang, Steven M. Lipkin, Robert A. Edwards Colorectal cancer (CRC) in patients with either IBD or DNA mismatch repair (MMR) defects differs from sporadic colon cancer. IBD-CRC and MMR-defective CRCs are more likely to be right sided, multifocal, mucinous, arise from areas of flat dysplasia, and have microsatellite instability. The Gia2-/- mouse model of IBD-CRC develops cancers that have all of these features. We found that the MMR protein MLH1 is downregulated in inflamed mucosa and cancers, and these tumors contain microsatellite instability and have impaired DNA damage responses. We have therefore investigated mechanisms of MLH1 silencing in colonic mucosa. MLH1 epigenetic silencing via promoter DNA methylation is a well established mechanism of carcinogenesis. We did not observe altered MLH1 promoter methylation in in inflamed Giα2-/- mucosa. Recently, hypoxia has been shown to silence MLH1 expression In Vitro by a mechanism involving histone deacetylation of the proximal promoter. We verified that hypoxic murine colonic epithelial cells (YAMC cells) downregulate MLH1 and have decreased acetylated histone H3 at the proximal MLH1 promoter by chromatin immunoprecipitation. HDAC inhibitor treatment upregulates acetyl-H3 levels and MLH1 expression In Vitro. Using 2-nitroimidazoles as In Vivo markers of hypoxia, we have identified tissue hypoxia in inflamed Giα2-/- mucosa and cancers that have decreased MLH1 (and its obligate binding partner PMS2) by qRT-PCR, immunohistochemistry, and western blot. In Vivo, treating Giα2-/mice with the HDAC inhibitor SAHA increases acetylated histone H3 levels and enhances MLH1 expression in colonic crypts. These data suggest that chronic hypoxic inflammation contributes to MMR- defective colon cancer via epigenetic histone modifications and silencing of the MLH1 locus.
M2009 PI3K Inhibition Suppresses Growth of Inflammation-Mediated Colon Cancer in Mice Takaaki Tsushimi, Hiroshi Saito, B. M. Evers Numerous studies have documented the link between chronic intestinal inflammation and colorectal cancer (CRC). Phosphatidylinositol 3-kinase (PI3K) stimulates the growth and invasion of a number of cancers including CRC. We have shown that wortmannin, a PI3K inhibitor, reduces the growth of human CRC xenografts In Vivo; the effect of PI3K inhibition on CRCs induced by inflammation is not known. The purpose of this study was to determine whether PI3K signaling plays a role in the development of CRC using a murine model of colonic inflammation and tumor development. METHODS. For all studies, male C57BL/6 mice (6-8 wks old) were used. To induce inflammation and tumor formation, mice were treated by a single intraperitoneal (ip) injection of the tumor promoter azoxymethane (AOM; 10 mg/kg) on day 0, followed by 2% dextran sodium sulfate (DSS) in drinking water for 7 days. i) In the first experiment, AOM/DSS-treated and control mice were sacrificed on week 12 and colonic mucosa harvested; activation of PI3K was assessed by Western blot for expression of PI3K downstream effector proteins (phosphorylated Akt, mTOR, p70S6K and 4E-BP1). ii) The experiment was repeated; disease activity index (DAI) was calculated and correlated with tumor formation. iii) Next, the experiment was repeated and mice subdivided to receive wortmannin (0.75 mg/kg, ip) or vehicle (5% EtOH) every 8 h on weeks 4, 6, 8 and 10 for 7 days; mice were sacrificed on week 12. RESULTS. Phosphorylation of Akt, mTOR, p70S6K and 4E-BP1 was significantly increased in the colonic tumors as compared to normal mucosa. Tumor size was significantly correlated with DAI (R = 0.89; p < 0.01). Wortmannin treatment significantly reduced the average size of colonic tumors compared to the vehicle-treated group (14.9 mm2 vs 30.3 mm2, respectively). CONCLUSIONS. PI3K activation is markedly increased in the colonic tumors arising from colonic inflammation. Inhibition of PI3K suppresses the growth of colonic tumors induced by AOM/ DSS suggesting that the PI3K/Akt pathway plays a critical role in inflammation-mediated development of colonic tumors. Inhibition of PI3K may represent a potential preventive therapy for CRCs induced by chronic inflammation.
M2012 Vav1 Acts As An Essential Modulator in Colitis Associated Colon Cancer Stefanie Zenker, Imke Atreya, Christoph Becker, Markus F. Neurath Introduction: The important intracellular adapter molecule and guanine nucleotide exchange factor Vav1 plays key roles in various intracellular signalling cascades. In contrast to the specific characterization of Vav1 in T lymphocytes, the impact of Vav1 in macrophages has not been studied extensively yet. We now analysed the effects of Vav1 deficiency in macrophages and hence the influence and function of Vav1 in the setting of intestinal inflammation and tumorigenesis. Methods: The susceptibility of Vav1 deficient (Vav1-/-) mice was tested in the dextran sulfate sodium (DSS)/azoxymethane (AOM) model of colitis associated colon cancer. Severity of mucosal inflammation and tumour burden was evaluated by miniendoscopy. In Vivo and In Vitro behaviour of Vav1-/-macrophages was further specified by immunhistology, ELISA, real time PCR and Western blotting. Results: Compared to wildtype (WT) Balb/c mice, treatment with DSS/AOM resulted in enhanced susceptibility of Vav1 deficient mice for colonic tumorigenesis. A higher number of colonic tumours and an increased tumour size could be detected in Vav1-/-mice compared to WT Balb/c animals. The evident infiltration of F4/80+macrophages in the inflamed intestinal mucosa of WT balb/c mice as well as of Vav1-/-mice exemplified that this cell population seemed to be very important in our tumour model. Interestingly, the early secretion of pro-inflammatory cytokine IL-6 was significantly enhanced by LPS-stimulated Vav1-/-macrophages In Vitro compared to WT cells. At the same time, secretion of TNF-alpha by macrophages was not markedly affected by the lack of Vav1 in our experimental setting. Furthermore, the lack of Vav1 in macrophages revealed in reduced cDNA- and protein level of SOCS3. These results implicate that active Vav1 is essential for LPS-mediated induction of SOCS3 in macrophages and thereby plays a central role for the regulation of IL-6 secretion. Conclusion: Vav1 exhibits a protective key role in inflammation associated colonic tumour genesis. Overall our results give evidence to the working hypothesis that the tumour-suppressive potential of Vav1 is trigged by its capacity to induce the expression of SOCS3 and thus the down regulation of pro-inflammatory cytokines.
M2010 Tumor Necrosis Factor Receptor Signaling in Intestinal Epithelial Cells May Be Directly Involved in Colitis-Associated Carcinogenesis Michio Onizawa, Takashi Nagaishi, Shigeru Oshima, Ryuichi Okamoto, Teruji Totsuka, Kiichiro Tsuchiya, Takanori Kanai, Hideo Yagita, Mamoru Watanabe Background & Aim: Treatment with anti-tumor necrosis factor (TNF) mAb has been accepted as a successful therapy for patients with inflammatory bowel diseases (IBD). It has been recently reported that blockade of TNF receptor (TNFR) 1 signaling in infiltrating hematopoietic cells may prevents the development of colitis-associated cancer (CAC). However, it remains unclear whether the TNF signaling in the epithelial cells is also involved in the development of CAC. To investigate this, we studied the effects of anti-TNF mAb in animal models of colitis and CAC. Methods & Results: Wild type C57BL/6 (WT B6) mice were treated with 3.0% DSS-contained drinking water for 5 days as acute phase followed by 5 days of recovering phase with regular water and subsequently sacrificed. Western blotting (WB) and immunohistochemistry (IHC) showed that the NF-κB pathway is activated in the colonic epithelia from DSS-treated mice in association with increased expression of TNF in inflamed mucosa. It was also observed that TNFR-2, but not TNFR1, was significantly upregulated in the epithelia from DSS-treated mice by quantitative RT-PCR and WB. Given these results, a mouse colonic epithelial cell line, CT26, was examined whether TNFR2 signaling is associated with NF-κB activation in these cells. Stimulation with recombinant (r) TNF led to NF-κB activation in CT26 cells in a dose dependent fashion, and blockade of TNF with a specific mAb, MP6-XT22, diminished such NF-κB activity. The expression of myosin light chain kinase (MLCK), which has been reported to be a responsible molecule to the permeability of epithelial barrier in colitis, was downregulated in CT26 cells when TNFR2 was silenced by specific siRNA transfection even in the presence of rTNF. We next induced the CAC model by pretreatment with azoxymethane (AOM) in DSS-receiving mice. Mice administered with AOM/DSS revealed multiple tumors in the middle to distal colon and the NF-κB pathway was further activated in association with more upregulated TNFR2 in the tumor compared to non-tumor area. Despite inability to reduce the severity of colitis, sequential MP6-XT22 treatment reduced the numbers and size of tumors in association with the NF-κB inactivation. IHC with anti-ZO-1 pAb showed that the disrupted epithelial tight
AGA Abstracts
M2013 Effect of Targeting the Neurokinin-1 Receptor On the Transition of Chronic Inflammation to Dysplasia Beatriz Pagan, Angel A. Isidro, Domenico Coppola, Jie Wu, Caroline B. Appleyard Patients with long-standing colitis have a significantly increased risk of developing colorectal cancer. Substance P and its neurokinin-1 receptor (NK-1R) are known to be involved in chronic colonic inflammation but their role in the transition to dysplasia is unclear. Aim: To investigate the effects of targeting the NK-1R in a novel model of colitis-associated dysplasia with a selective NK-1R antagonist. Methods: Chronic colitis was induced in male Sprague Dawley rats by the administration of trinitrobenzene sulfonic acid (TNBS; 30 mg in 50% ethanol ic), followed six weeks later by reactivation with TNBS (5 mg/kg iv) for three days. To induce colitis-associated dysplasia the rats then received TNBS (iv) twice a week for ten weeks. One group received the NK-1R antagonist SR140333 (1 mg/kg ip) twice a week for ten weeks; the rest received vehicle (n=22/group). After sacrifice the colons were removed and analyzed for total macroscopic damage, microscopic damage and presence of dysplasia. The expression of the downstream signalling components and cell proliferation were analyzed by immunohistochemical staining and quantitative real-time RT-PCR. Results: Those animals receiving the NK-1R antagonist gained significantly less weight than the vehicle treated group throughout the study, however, these animals had significantly less macroscopic (p<0.01) and microscopic damage (p<0.01) than the vehicle treated-controls.
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