草苁蓉环烯醚萜苷调控TGF-β介导的EMT抑制肝癌侵袭转移的机制研究

Epithelial-mesenchymal transition (EMT) plays a key role in tumor invasion and metastasis, and TGF-β is the most thoroughly studied EMT-inducing factor. Our previous studies found that Boschniakia rossica iridoid glycosides inhibit angiogenesis of transplanted hepatocarcinoma tissue in mice, reduce the ECM deposition of hepatic preneoplastic lesions via regulation of MMP/TIMP ratio in rats, and inhibit the migration and EMT of hepatoma cells in vitro. In these processes, the expression of TGF-β is down-regulated by Boschniakia rossica iridoid glycosides. The results suggest that Boschniakia rossica iridoid glycosides may inhibit the invasion and metastasis of hepatocellular carcinoma by TGF-β-mediated regulation of epithelial-mesenchymal transition. Therefore, this project is intended to further explore the role of TGF-β pathway and the cross-talk between TGF-β/Smad classic pathway and PI3K/Akt/GSK-3β pathway in EMT process of hepatocellular carcinoma and provide a possible target for the regulation of invasion and metastasis of hepatocellular carcinoma; reveal the molecular mechanism of Boschniakia rossica iridoid glycosides for the TGF-β-mediated regulation of EMT, determine the exact target for the regulation of EMT in hepatocellular carcinoma, and clarify the inhibitory mechanisms and characteristics of Boschniakia rossica iridoid glycosides on invasion and metastasis of hepatocellular carcinoma by TGF-β-mediated regulation of EMT. This project will enrich the medicinal connotation of Boschniakia rossica, and provide a new strategy for the prevention and treatment of liver cancer.

上皮间质转化（EMT）在肿瘤侵袭转移过程中发挥着关键作用，而TGF-β是目前研究最为深入的EMT诱导因子。前期研究发现，草苁蓉环烯醚萜苷抑制小鼠肝癌移植瘤血管生成，调节MMP/TIMP比值降低大鼠肝脏癌前病变组织ECM沉积，体外抑制肝癌细胞迁移和EMT发生。这些过程中均发现草苁蓉环烯醚萜苷下调TGF-β1表达。提示，草苁蓉环烯醚萜苷可通过介导TGF-β通路调控EMT抑制肝癌侵袭转移。本项目拟以TGF-β介导的EMT为切入点，探讨TGF-β通路在肝癌细胞EMT过程中的角色地位，以及此过程中TGF-β/Smad经典通路与PI3K/Akt/GSK-3β通路的交叉对话，为肝癌侵袭转移调控提供可能靶标；揭示草苁蓉环烯醚萜苷介导TGF-β调控肝癌细胞EMT的分子机制，确定其靶向调控EMT的确切靶标，阐明其介导TGF-β通路调控EMT抑制肝癌侵袭转移的机制和作用特点。本项目将为肝癌防治策略提供新的途径。

草苁蓉是长白山珍贵药用植物。课题组发现其环烯醚萜苷抑制小鼠肝癌移植瘤血管生成，调节MMP/TIMP比值，降低大鼠肝脏癌前病变组织ECM沉积，体外抑制肝癌细胞迁移和EMT发生。这些过程中均发现草苁蓉环烯醚萜苷下调TGF-β1表达。而EMT在肿瘤侵袭转移过程中发挥着关键作用，其中TGF-β是目前研究最为深入的EMT诱导因子，且与MAPK和PI3K/Akt通路关系密切。因此，本项目以TGF-β介导的EMT为切入点，探讨了TGF-β通路在肝癌细胞EMT过程中的角色地位，以及TGF-β/Smad经典通路与MAPK、PI3K/Akt通路的交叉对话；揭示了草苁蓉环烯醚萜苷介导TGF-β调控肝癌细胞EMT的分子机制，阐明了其介导TGF-β通路调控EMT抑制肝癌侵袭转移的作用特点。结果显示，草苁蓉环烯醚萜苷联合5-Fu体外干预肝癌细胞EMT具有相加或协同效果，逆转TGF-β1介导的肝癌EMT过程。即，通过调控TGF-β通路以及MAPK和PI3K/Akt通路蛋白，调节EMT相关蛋白的表达，从而抑制肝癌细胞迁移和侵袭。动物研究表明，草苁蓉环烯醚萜苷对肝癌细胞显示生长抑制作用，并抑制肝癌细胞侵袭、转移，降低MMP2、MMP7、MMP9、Snail、Slug蛋白表达，上调E-钙黏蛋白表达，下调N-钙黏蛋白和波形蛋白的表达。这些结果提示，草苁蓉环烯醚萜苷通过TGF-β/Smads、MAPK、PI3K途径调控肝癌细胞EMT抑制肝癌侵袭转移。本项目对肝癌的发病机制研究与防治策略以及长白山草苁蓉资源的开发和利用具有重要意义。