hTERT活化Gli1的分子机制及其在胃癌上皮间叶转化(EMT)中的作用研究

In our previous study, it had been proved that hTERT is tightly asscotiated with the EMT ability of cancer cell, but the mechanism remains unclear. Some researchers revealed that hTERT could increase the ability of EMT by stimulating the Wnt signaling pathway. But our previous study shows that the inhibiton of Wnt signaling pathway by special inhibitor could not entirely reverse the EMT induced by hTERT , which suggests the existence of some other pathways participate in this process apart from the Wnt signaling pathway. Hedgehog/Gli1 signaling pathway is another important pathway involves with the EMT. We found that the expressions level of Gli1 was positive correlated to the level of hTERT in gastric cancer tissues. What’s more, the over-expression of hTERT in BGC-823 cells increased the expression level of Gli1. The EMT ability of BGC-823 cells caused by hTERT was significantly decreased when Gli1 was inhibited. The results above suggested hTERT promoted EMT through up-regulating the expression of Gli1. This study is planning to investigate the molecular mechanism of the regulation of hTERT to Gli1 and its role in the EMT of gastric cancer, by luciferase experiment, Immunoprecipitation and animal experiment, etc. which will provide a new target point for tumor prevention and cure based on hTERT.

文献及我们的研究表明端粒酶逆转录酶（hTERT）与肿瘤上皮间叶转化(EMT)密切相关，然而机制尚不清楚。文献报道hTERT可通过Wnt信号通路促进肿瘤的EMT，而本课题组前期研究发现，干扰Wnt信号通路并不能完全逆转hTERT诱导的胃癌EMT，推测可能存在其他通路。Hh/Gli信号通路是另一个调控肿瘤EMT的重要信号通路，预实验发现hTERT与Gli1在胃癌组织中的表达呈正相关性，过表达hTERT可上调Gli1的表达，并且抑制Gli1可明显减弱hTERT引起的EMT变化，提示hTERT可以通过调控Hh/Gli进而促进胃癌细胞EMT。据此，本课题拟通过双荧光素酶实验、免疫共沉淀及动物实验等，探讨hTERT上调Gli1的具体分子机制及其在胃癌EMT中的作用，以期进一步完善hTERT参与肿瘤发生发展的机制，旨在为基于hTERT的肿瘤治疗提供新的理论依据.

既往研究表明端粒酶逆转录酶（hTERT）与肿瘤上皮间叶转化(EMT)密切相关，然而机制尚不清楚。文献报道hTERT可通过Wnt信号通路促进肿瘤的EMT，然而本研究发现，干扰Wnt信号通路并不能完全逆转hTERT诱导的胃癌EMT，由此推测可能存在其他通路。Hedgehog/Gli信号通路是另一个调控肿瘤EMT的重要信号通路，我们发现hTERT与Gli1在胃癌组织中的表达呈明显正相关。在胃癌细胞中过表达hTERT可上调Gli1的mRNA及蛋白水平，并且抑制Gli1可明显减弱hTERT引起的EMT变化。通过IP与CHIP实验证实hTERT通过与sp1共同作用于Gli1的启动子，促进Gli1转录。综上，本研究阐明了hTERT可以通过非经典HH通路活化Gli1，促进胃癌细胞 EMT 的发生，进一步完善了hTERT 参与肿瘤EMT的分子机制。