mTOR/FAM135B/ATG16L1信号通路抑制自噬发生在食管鳞癌发生发展中的作用及机制研究

The role of Autophagy in tumor development, progression and chemoresistance is still in controversy. Previous research models were limited to tumor cells of certain malignant degree and autophagy related genes knockout mice, failing to track the history of malignant transformation of normal cells and analyze the possible causal relationship. In our previous study, we performed whole genome sequencing and figured out a novel esophageal squamous cell carcinoma (ESCC) driver gene FAM135B, which was frequently amplificated and significantly associated with poor survival. Further study revealed that FAM135B interacted with autophagy related gene ATG16L1 physically and suppressed autophagy. Additionally, we found that the protein level of FAM135B was upregulated by mTOR signaling pathway. To further investigate the role of FAM135B in ESCC development, we constructed FAM135B transgenic mice. In the present study, we seek to dissect the biological functions of FAM135B, with particular focus on autophagy in different stages of ESCC initiation and progression by using chemical agent 4-NQO to induce ESCC development in FAM135B transgenic mice. Further, we pursue to elucidate the underlying molecular mechanisms and illuminate the regulation relationship among mTOR, FAM135B and ATG16L1. Lastly, we will explore the clinical translation potential by targeting autophagy in FAM135B overexpression models in vitro and in vivo.

自噬在肿瘤发生发展和耐药中的作用尚存很多争议，以往的研究模型局限于特定恶变程度的肿瘤细胞或自噬基因敲除小鼠自发肿瘤模型，未能监控正常细胞恶变全过程中自噬的发生情况并分析其因果关系。课题组前期通过全基因组测序，首次揭示了FAM135B是一个新型的食管鳞癌相关基因（高频扩增并与生存预后负相关），发现其与自噬相关蛋白ATG16L1存在相互作用，功能研究也证实FAM135B能够抑制自噬的发生。进一步的分子机制探索初步揭示mTOR能够上调FAM135B的蛋白水平。本项目将基于已构建成功的FAM135B转基因小鼠，通过给予食管癌诱发剂4-NQO处理，监测食管上皮细胞恶变全过程，深入研究FAM135B在肿瘤发生发展中的作用，阐明mTOR对FAM135B/ATG16L1的调控机制，明确FAM135B在自噬过程中的功能及其在肿瘤发生发展、化疗敏感性等方面的作用，为食管鳞癌的诊治提供有力的理论。

自噬在肿瘤发生发展和耐药中的作用尚存很多争议。课题组前期通过全基因组测序，首次揭示了FAM135B是一个新型的食管鳞癌相关基因（高频扩增并与生存预后负相关）。本项目研究发现FAM135B能够抑制自噬过程，其背后的分子机制是FAM135B能够与自噬关键蛋白ATG16L1相互作用，从而抑制了ATG16L1与ATG5/ATG12相互作用，进而抑制了自噬体的形成过程。进一步的分子机制研究揭示了mTOR能够上调FAM135B的蛋白水平并参与自噬过程。我们的研究还发现FAM135B过表达的转基因小鼠对食管癌诱发剂4-NQO更为敏感，更容易发生食管癌。同时，我们的研究还发现FAM135B过表达能够导致细胞对化疗药物产生抗性，揭示了FAM135B能够与DNA损伤修复关键蛋白TIP60相互作用，并促进了它的乙酰转移酶酶活性，进而增强了TIP60与ATM的相互作用，最终增强ATM及其下游的活性，促进DNA损伤修复。在对自噬过程的探索中，我们发现一种自噬小体转运的新机制，阐明了Nlp能够促进FYCO1与Rab7相互作用，进而促进自噬小体与溶酶体融合，从而促进自噬发生。这些研究明确FAM135B在自噬过程中的功能及其在肿瘤发生发展、化疗敏感性等方面的作用，为食管鳞癌的诊治提供有力的理论。同时，揭示了自噬小体运输的可能机制，为理解自噬发生过程提供了新的见解。