沉默信息调节因子1在胃癌发展中的作用机制研究

Effect and mechanism of SIRT1 in development of gastric cancer

目的探讨沉默信息调节因子1(SIRT1)在胃癌发展中的可能分子机制和信号通路。方法人胃癌细胞株HGC-27分为转染shRNA-SIRT1组及对照组,应用实时定量PCR及免疫印迹法检测转录激活因子3(STAT3)在两组中的表达;免疫共沉淀法分析SIRT1同STAT3、磷酸化STAT3在胃癌中的相互作用关系;建立STAT3敲除转基因小鼠胃癌模型,免疫组织化学方法检测STAT3敲除转基因小鼠胃癌组织中SIRT1的表达情况。结果 STAT3mRNA在shRNA-SIRT1组和对照组中表达无明显区别,免疫印迹检测发现STAT3蛋白水平在胃癌细胞组和空转组中较shRNA组中表达增高,磷酸化P-STAT3与STAT3表达水平相同,而乙酰化A-STAT3的表达水平正好相反。免疫共沉淀发现SIRT1同STAT3和PSTAT3能形成复合物。应用STAT3敲除转基因小鼠胃癌模型,进行SIRT1表达的对比研究,发现SIRT1在STAT3敲除转基因小鼠胃癌组织中的表达较对照组降低。结论通过研究SIRT1同STAT3在胃癌中的相互作用关系,推测SIRT1可能通过对STA13的去乙酰化作用,间接增强活化的磷酸化STAT3,并形成SIRT1-STAT3复合物,促进胃癌的发展。SIRT1可能通过JAK1-STAT3途径或直接激活STAT3参与胃癌的进展过程。

Objective To explore the possible molecular mechanism and signal channel of SIRT1 in progress of gas-tric cancer. Method STAT3 expression in shRNA-SIRT1 infected gastric cancer cells and control group were detec-ted by real time PCR and immunoblotting. Co-immunoprecipitation was used for analyzing the relationship between SIRT1 and STAT3,PSTAT3 in gastric cancer;STAT3 knock out mice model was successfully built. SIRT1 expression in gastric cancer tissue were detected by the method of immunohistochemical staining in STAT3-KO mice. Result There was no obvious difference of STAT3 mRNA level between shRNA-SIRT1 group and control,but we found the protein level of STAT3 was higher on gastric cancer cell group and control by immunoblotting analysis. P-STAT3 was same with STAT3,but the A-STAT3 was opposite. The SIRT1 could form complexes with STAT3 and P-STAT3 by co-immunoprecipitation. After analyzing the SIRT1 expression in STAT3 knock out mice gastric cancer model, we found the SIRT1 was lower in STAT3-KO group. It indicated STAT3 interacted with SIRT1 in gastric cancer. Con-clusion We consider that SIRT1 may indirectly increase the phosphorylation STAT3 by deacetylating STAT3 and form a complex,promoting the progress of gastric cancer. Through acting at JAK1-STAT3 or activating STAT3 direct-ly,SIRT1 participates in the development of gastric cancer.