| Object Pancreatic cancer is one of the most malignant tumor in the digestive system. Due to the diagnosis is difficult in the early stage, and lacking of effective treatments, the five-year survival rate is only 6%.Tumor growth not only associate with unlimited proliferation of the cell, and is also closely related with tumor angiogenesis. The effective restrain of the formation of tumor blood vessels and the limited proliferation tumor development are of great use to treat the cancer. Angiotensin-(1-7) [Ang-(1-7)] is an endogenous heptapeptide of the rennin-angiotensin system with anti-proliferative and anti-angiogenic properties. The main objective of this study was to determine whether Ang-(1-7) has the same properties in human pancreatic tumor xenpgraft model. Human SW1990 pancreatic cancer cells were injected into athtmic mice to establish the pancreatic tumor model.Methods 1. SW1990 cells were grown at 37℃ in a atmosphere of 5% CO2 in RPMI 1640 medium containing 10% fetal bovine serum. Mice were inoculated subcutaneously with 1x107 SW1990 cells in 0.1 ml phosphate buffered saline into the right back to establish the pancreatic tumor model. 2. Athymic mice with tumors were treated for 28 days with saline, high-dose Ang-(1-7), low-dose Ang-(1-7) and A779 plus Ang-(1-7), delivered by implanted minipumps.3. Tumor were fixed in 4% paraformaldehyde for 24 h before embedding in paraffin. The embedded tumors were cut into 4-μm-thick sections and stained with hematoxylin and eosin to determine morphology. AT1 R protein were determined by immunostaining with an antibody to AT1 R. Cell proliferation in tumors was detected by immunostaining with an antibody to Ki67. The tumor angiogenesis were detected with an antibody to VEGF and endothelial cells were detected with an antibody to Endomucin. 4. All the rest of the tumor to verification by the method of Real- time PCR AT1 R m RNA level and the expression of VEGF is consistent with the protein expression level. PfrResults 1. Ang-(1-7) infusion resulted in a significant reduction in average tumor volume compared with the tumors in saline treatment at the end of 28 days. The weight of tumors from mice treated with Ang-(1-7) in different groups all less than the tumors of mice infused with saline 2. The tumor tissue is detected by immunohistochemistry include Ki67, VEGF, Endomucin. There is an obvious decline in tumor tissues after the Ang-(1-7) treatment compared with the saline-treated. AT1 R was also significantly lower. There is also a significant difference during high-dose group with low-dose group and add antagonist drugs group,while low-dose group and add A779 antagonists group showed no significant difference. 3. The Real- time PCR test, according to the results of treatment group AT1 R and VEGF is a significant reduction in the normal saline group, high-dose group and small dose group and to join also showed significant difference antagonist drugs group, low-dose group and join A779 antagonist group no significant difference, in line with immunohistochemical results. PsgioleConclusion These results correlate with a reduction in the proliferation marker Ki67 and angiogenesis marker endomucin and VEGF in all the Ang-(1-7)-infused tumors compared with the saline-infused tumors. Treatment with Ang-(1-7) significantly reduced angiotensin Ⅱtype 1 receptor(AT1R) m RNA and protein in tumors of Ang-(1-7)-infused mice when compared with mice treated with saline. Furthermore, mice treated with A779 plus Ang-(1-7) showed significantly decreased in Ki67, endomucin, VEGF and AT1 R when compared with mice treated with the same dose Ang-(1-7). All of our results suggest that Ang-(1-7) may has anti-proliferative and anti-angiogenic functions via AT1 R except its special receptor Mas. |
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