自噬相关转录因子TFEB调控胃癌细胞耐药的功能和机制研究

Chemodrug resistance is the main cause of the failure of the chemo treatment against gastric cancer. Cancer cells could confer autophagy to survive under chemotherapy, which is a crucial mechanism of chemodrug resistance. The transcription factor TFEB could induce autophagy and LAMP1 mediated lysosomal exocytosis, which has been reported to play important roles in many metabolic storage diseases. However, the role of TFEB in cancer chemodrug resistance remains elusive. We previously found that TFEB is upregulated in gastric chemodrug resistant cell lines. Inhibition of TFEB could enhance the cancer cell sensitivity to the chemodrugs. Moreover, nuclear TFEB expression is highly correlated with the poor prognosis of gastric cancer patients. All above results indicated that TFEB might play an important role in modulating chemodrug resistance of gastric cancer and it might be a crucial molecule that influence the patients’ survival time. In the current project, we aim to validate the function of TFEB in the chemodrug resistance of gastric cancer through in vitro and in vivo functional studies. To dissect the mechanism, we plan to study the impact of TFEB on autophagy as well as it’s modulation on LAMP1 mediated lysosomal exocytosis. Furthermore, we will utilize the high-throughput omics methods including microarray, iTRAQ and ChIP-Seq to identify the target molecules of TFEB and the related signaling pathways. Overall, this project will elucidate the function of TFEB in chemodrug resistance of gastric cancer and the underlying mechanisms, deepen the understanding of the mechanisms of cancer chemodrug resistance, and provide novel potential targets for reversing chemodrug resistance in gastric cancer.

耐药是胃癌化疗失败的主要原因。自噬是肿瘤细胞在化疗条件下存活的重要机制。转录因子TFEB能够调控自噬和溶酶体外排，在多种疾病中发挥重要作用，但其在肿瘤耐药中作用尚不清楚。我们通过前期研究，发现TFEB在胃癌耐药细胞系中表达升高，抑制TFEB能够增强耐药细胞的化疗敏感性，且TFEB核表达与胃癌患者预后密切相关，提示TFEB在胃癌耐药中发挥重要作用，可能是影响胃癌化疗疗效和患者生存期的关键分子。本研究拟通过体内外功能实验，阐明TFEB在胃癌耐药中发挥的作用；机制层面，阐明TFEB通过调控自噬促进胃癌耐药，并研究其通过调控LAMP1促进溶酶体外排参与胃癌耐药。此外，我们将联合应用基因芯片、iTRAQ和ChIP-Seq技术，揭示受TFEB调控的下游关键效应靶分子和信号调控网络。本项目将阐明TFEB在胃癌耐药中的作用及机制，有助于深化对肿瘤耐药的认识，为逆转胃癌耐药提供新靶点。

我国胃癌的发病率和死亡率均位居恶性肿瘤前列。除手术外,进展期胃癌的治疗主要依靠化学药物治疗。耐药现象常常导致胃癌患者有药无用,甚至无药可用,最终导致化疗失败,预后极差。自噬是细胞清除胞内受损蛋白和细胞器的重要机制,能够被肿瘤细胞利用,成为肿瘤在各种恶劣情况下存活的重要方式。既往研究发现mTORC1下游的转录因子TFEB是在转录水平调控自噬的关键分子,其调控的细胞自噬在脂质代谢紊乱、帕金森等多种代谢蓄积性疾病中发挥关键调控作用。然而, TFEB在胃癌中所扮演的角色尚不明确。本研究通过系统研究TFEB在胃癌中的功能和机制，发现1.自噬对化疗情况下胃癌细胞的存活具有重要保护作用,抑制自噬能够增加胃癌的化疗效果。2.mTORC1/TFEB通路是调控自噬的重要通路,是化疗药物相关自噬的关键转录调控途径。3.TFEB作为mTORC1下游的重要的自噬转录水平调节因子,在胃癌组织中表达明显升高,且主要表达于胞核,其表达水平与胃癌预后密切相关;化疗药物表柔比星和顺铂等能够通过抑制mTORC1,促进TFEB发生去磷酸化,去磷酸化的TFEB能够发生核转位，发挥其调控自噬与溶酶体生成的转录活性。4.TFEB通过转录调控自噬和LAMP1介导的溶酶体功能,促进胃癌细胞在化疗情况下的存活。5.发现Hippo通路重要分子STK38是TFEB重要的上游调控分子。本研究深化了对自噬诱导化疗耐药的认识，揭示了STK38-TFEB-LAMP1通路促进胃癌细胞在化疗环境中存活的重要作用，有望为判断和预测胃癌化疗抵抗提供新的标志物，为提高胃癌化疗疗效提供了新的干预靶点。