The Carcinogenic Effect Of The Repair Proteins Of DNA Damage And The Cancer Stem Cell Markers For Pancreatic Cancer In Sprague-Dawely Rat

PartyⅠEstablishment of a model for pancreatic cancer in Sprague-Dawely rat and its pathological studyObjective To establish a model of pancreatic cancer induced by dimethylbenzanthracene(DMBA) in Sprague-Dawely rats and investigate the pathological changes and inhibitive effect of trichostatin A (TSA) on the carcinogenesis and growth of pancreatic cancer.Methods The membrane and panrenchyma (about 1mm depth) of rat pancreas was opened to implant a higher dose (9 mg) of DMBA in group A and group B rats, and then the incision was closed with interrupted sutures. The rats of group B was then treated with 1 ml TSA saline solution (1μg/ml) via ip weekly. The pancreas and other main organs of extra-pancreas of rats sacrificed within 3-5 months were studied by macrograph and under-microscopy.Results (1) The prevalence of pancreatic cancer among rats of group A within 3-5 months was 48.7%(18/37), pathological types including 17 cases with pancreatic ductal adenocarcinoma and 1 case with fibrosarcoma. The prevalence of pancreatic cancer for five months was higher than that for three or four months, but no satistical difference was found(P>0.05). (2) The prevalence of pancreatic cancer among rats of group B within 3-5 months was 33.3%(12/36), pathological types including 11 cases with pancreatic ductal adenocarcinoma and 1 case with fibrosarcoma. The prevalence of pancreatic cancer for five months was higher than that for three or four month, but no significance was found (P>0.05). (3) The prevalence of pancreatic cancer in group A was higher than that in group B, but no satastical difference was found (P> 0.05). (4) The maximal diameter of neoplastic mass was significantly higher in group A than that in group B (P<0.05). (5) Non-cancerous pancreatic tissues in group A and group B showed the hyperplasia to atypical-hyperplasia of ductal epitheli of pancreas.19 cases out of non-cancerous pancreatic tissues in group A included 5 cases of mild-atypical hyperplasia and 10 cases of moderately to severely-atypical hyperplasia of ductal epithelial cells.24 cases out of non-cancerous pancreatic tissuer in group B included 10 cases of mild-atypical hyperplasia and 8 cases of moderately to severely-atypical hyperplasia of ductal epithelial cells. But no satastical difference compared group A with group B was found (P>0.05). (6) The pancreas of group c and other main organs of group A and group B had no pathological changes of macrograph and under-microscopy.Conclusions Higher dose of DMBA implanted directly into the parenchyma of pancreas could obtain an ideal pancreatic cancer model with high incidence in a short time. TSA might have an inhibitive effect on the carcinogenesis and growth of rat pancreatic ductal adenocarcinoma. Party II Expression of repair proteins of DNA damage and their significances in pancreatic cancer and non-cancerous pancreatic tissues of Sprague-Dawely(SD) ratsObjective To establish a model of pancreatic cancer induced by dimethylbenzantracene (DMBA) in SD rats, and detect the expressive levels of repair proteins of DNA damage(MGMT, ERCC1, hMSH2 and hMLH1) and their effect on carcinogenesis of rat pancreas.Methods DMBA was directly implanted into the parenchyma of pancreas in rats (group A+ group B), The rats of group B were treated with 1ml TSA saline solution (1μg/ml) via ip weekly. The carcinogenesis of rats executed within 3～5 months in group A and group B was observed by macrography and under microscopy. Meanwhile, the rats in the control group (group C) were executed in 5 months. The En VisionTM immunohistochemistry was used for assaying the expressive levels of MGMT, ERCC1, hMSH2 and hMLH1 in conventional paraffin-embedded sections from above pancreatic specimens.Results (1) The incidence of pancreatic cancer in group A within 3～5 months was 48.7%(18/37), including 17 cases of pancreatic ductal adenocarcinoma and 1 case of fibrosarcoma. The incidence of pancreatic cancer in group B was 33.3%(12/36), including 11 cases of pancreatic ductal adenocarcinoma and 1 cases of fibrosarcoma. The maximal diameter of tumor mass in group A was larger than that in group B (P<0.05). No pathological changes were found in pancreas of group C and other main organs of group A and group B. (2) The positive rates of MGMT, ERCC1, hMSH2 and hMLH1 were significantly lower in ductal adenocarcinoma of group A+group B than those in non-cancerous pancreatic tissues of group A+group B(P<0.05 or P<0.01). No statistial differences were found among the expression rates of MGMT, ERCC1, hMSH2 and hMLH1 in ductal adenocarcinoma and non-cancerous pancreatic tissues of group A(P>0.05). The positive rates of MGMT, ERCC1, hMSH2 and hMLH1 were significantly lower in ductal adenocarcinoma of group B than those in non-cancerous pancreatic tissues of group B(P≤0.05). Pancreas of group C was positive expression of MGMT, ERCC1, hMSH2 and hMLH1.2 cases of fibrosarcoma was negative expression of MGMT, ERCC1, hMSH2 and hMLH1.Conclusions DMBA directly implanted into the parenchyma of pancreas can obtain an ideal pancreatic cancer model with high incidence in a short time. TSA may have an inhibitive effect on the carcinogenesis in rat pancreas. The repair proteins of DNA damage, including MGMT, ERCC1, hMSH2 and hMLH1, might have loss expressions and important effects on the carcinogenesis induced by DMBA in rat pancreas. Party III Expression of cancer stem cell markers and its significances in pancreatic cancer and non-canerous pancreatic tissues of Sprague-Dawely(SD)ratsObjective To establish a model of pancreectic cancer induced by dimethylbenzanthracene(DMBA) in SD rats, and detect the expressive levels of cancer stem cell markers (PSCA,Oct-4, CD24 and CD44V6)in the carcinogenesis and progression and their significances.Methods DMBA was directly implanted into the parenchyma of pancreas in rats (group A+B). The rats of group B were treated with 1ml TSA saline solution (1μg/me)via ip weekly.The carcinogenesis of rats executed within 3-5 months in group A and group B were observed by HE staining and macrography. Meanwhile, the rats in the control (group C)were executed in 5 months. The En VisionTM immunohistochemistry was used for assaying the expressive levels of PSCA, Oct-4 CD24, and CD44V6.Results (1)The incidence of pancreatic cancer in group A within 3-5 months was 48.7%(18/37),including 17 cases of pancreatic ductal adenocarcinoma and 1 case of fibrosarcoma. The incidence of pancreatic cancer in group B was 33.3%(12/36), including 11 cases of pancreatic ductal adenocarcinoma and 1 case of fibrosarcoma. The maxial diameter of tumor mass in group A was larger than that in group B(P<005). No pathological changes were found in pancreas of group C and other main organ of group A and group B. (2)The positive rates of PSCA,Oct-4,CD24 and CD44V6 were significantly higher in pancreatic ductal adenacarcinoma of group A+ group B than those in non-cancerous pancreatic tissues of group A+ group B (P<0.01). The positive rates of PSCA, Oct-4, CD24 and CD44V6 were significantly higher in pancreatic cancer of group A or group B than those in non-cancerous tissues corresponding group A or group B (P<0.01). No positive case of PSCA, Oct-4, CD24 and CD44V6 was found the pancreatic tissues of group C.Conclusions DMBA directly implanted into the parenchyma of parcreas can obtain an ideal pancreatic cancer model with high incidence in a short time. TSA may have an inhibitive effect on the carcinogenesis and growth of pancreatic cancer in rats. Cancer stem cells and their markers(PSCA, Oct4, CD24, CD44V6)might have important effects on the carcinogenesis and progression of rat pancreatic cancer induced by DMBA.