Type Cytoplasm Dissolved Oxygen Catecholamine Level Methyltransferase (s - Comt) Affect The Mechanism Of Pancreatic Cancer Biology Behavior Research

BackgroundPancreatic adenocarcinoma is generally thought to arise from pancreatic ductal cells, its5-year survival rate is less than5%. The high mortality rate for pancreatic cancer is primarily due to diagnosis mostly at advanced stage and no sensitive tools for early detection. Although surgical resection remains the only curative treatment, there are about only15-20%of patients have resectable disease. For locally advanced, unresectable, and metastatic disease, chemotherapy seems to hold the greatest promise, but the dismal prognosis is partly due to its intrinsic and extrinsic drug resistance characteristics. Pancreatic cancer remains a challenging problem during the21st century. In previous work we found that COMT might be the candidate immunogenic antigens of pancreatic cancer. Catechol-O-methyltransferase (COMT) is widely distributed throughout the body, COMT is involved in catechol homeostasis and catalyzes the methylation of both2-OH and4-OH catechol estrogens to methoxy estrogens. Several studies have shown evidence that COMT may play both a regulatory and protective role.Objective1. To indentify and validate the expression of MB-COMT, S-COMT in sixteen pancreatic cancer tissue and nine cell lines.2. To explore the exact molecular mechanism of COMT involved in the development of pancreatic cancer.3. To explore the correlation between COMT expression and patients’ clinicopathological factors in pancreatic cancer.Methods1. The expression of COMT in sixteen pancreatic cancer tissue and nine pancreatic cancer cell lines (SW1990, Su86.86, AsPC-1, BxPC-3, Capan-1, Panc-1, MIAPaCa-2, Colo357, and T3M4) were tested by Western blotting analysis. Three human pancreatic cancer cell lines as Panc-1、MIAPaCa-2and SW1990were employed for in vitro experiment.2. The S-COMT plasmid was constructed in our laboratory. Specific COMT siRNA was designed according to the cDNA sequence of COMT. Observe the cellular ability of proliferation, apoptosis rate, migration and invasion in vitro through inhibition or overexpression of S-COMT expression in human pancreatic cancer cell lines.3. Observe the expression level of proteins related to proliferation (PI3K, p-Akt, GSK3, p53, p27, p21, CyclinD1, CDK4), apoptosis (Bax、Bad、Bcl-2、Bim), migration and invasion (E-cadherin) after inhibition or overexpression of COMT expression in human pancreatic cancer cell lines. To explore the molecular mechanism of S-COMT involved in the development of pancreatic cancer.4. Lentvims vectors contained S-COMT gene and siRNA were conducted with a high performance homologous recombination system, and then were transduced into human pancreatic cancer BxPC-3cells.The animal experiment was used to validate the results we got in vitro study.5. Fifty-three human pancreatic cancer and their corresponding nontumorous tissue samples were collected at the time of surgical resection at Department of General Surgery, Peking Union Medical College Hospital (PUMCH). The relationship between S-COMT expression and clinicopathological and prognosis variables of patients were further evaluated by immunohistochemistry method.Results1. Both MB-COMT and S-COMT proteins were tested in pancreatic cancer and normal pancreatic tissues by Western blotting analysis, the expression of S-COMT was elevated in pancreatic cancer as compared to the matching normal pancreatic tissues significantly(p=0.0129). All of nine pancreatic cancer cell lines are expressions COMT protein. Higher S-COMT expression levels were detected in SW1990、AsPC-1、BxPC-3cell compared with the other cell lines. Lower S-COMT expression levels were detected in Panc-1、Su86.86、Canpan-1cell lines.2. In vitro, our current studies reveal an encompassing model for the role of S-COMT in regulating pancreatic cancer development. We confirmed the impact of S-COMT suppression on proliferative potential, migration, invasion and causing apoptosis in pancreatic cancer cell lines. In vivo, the anti-cancer effects of S-COMT targeted interventions were also determined using mice xenograft model of pancreatic cancer.3. To further characterize the affect of S-COMT on pancreatic cancer, a preliminary analysis of the impact of S-COMT on critical intracellular proteins output was performed in pancreatic cancer cell lines. We found that S-COMT expression can affect proteins related to proliferation (PI3K, p-Akt, GSK3, p53, p27, p21, CyclinD1, CDK4), apoptosis (Bax、Bad、Bcl-2、Bim), migration and invasion (E-cadherin). Our research provides strong evidence that S-COMT affects the PI3K/Akt and p53signaling pathways in pancreatic cancer development.4. Immunohistochemistry staining showed that the high expression rate of S-COMT in tumor tissue was significantly higher than in normal tissue (P=0.0001) There were correlation between S-COMT expression, local recurrence and tumor stage. Kaplan-Meier analysis showed that high expression of S-COMT had a significantly better prognosis. However, S-COMT expression is not an independent prognostic factor of pancreatic cancer.Conclusions1. These findings suggest that S-COMT may negatively control the progression of pancreatic cancer, it may affect pancreatic cancer development by the PI3K/Akt and p53signaling pathways both in in vitro and vivo.2. High expression rate of S-COMT was observed in pancreatic cancer tissue. There were correlation between S-COMT expression, local recurrence and tumor stage. S-COMT expression predicts a favorable prognosis and may serve as a novel prognosis and diagnostic marker.