AIF1L调节β-catenin核转位抑制肾癌细胞干性和转移的分子机制研究

肌动蛋白结合蛋白AIF1L与肾足细胞骨架稳定性相关，其在肾癌中的功能尚无报道。预实验和TCGA分析发现AIF1L在肾癌中低表达，与肾癌恶性进展负相关，过表达AIF1L可抑制肾癌细胞增殖、迁移、侵袭和成球能力；生物信息学分析提示其与细胞粘附、紧密连接和肿瘤干细胞标志物CD44、CXCR4明显相关；进一步研究发现AIF1L可抑制β-catenin核转位，降低CD44和Vimentin表达，增加E-cadherin和ZO-1表达。据此推测：AIF1L通过β-catenin核转位降低细胞干性和EMT，抑制肾癌转移。本项目拟在临床标本、细胞和动物水平通过组织芯片、生物信息学、蛋白质谱、Co-IP等方法探索AIF1L抑制肾癌转移的功能及信号通路；揭示AIF1L抑制β-catenin核转位的分子机制；明确其与肾癌组织病理特征的关系。旨在阐明AIF1L抑制肾癌转移的功能及分子机制，为肾癌诊疗提供潜在靶点。

AIF1L is one of the actin-binding proteins that plays important roles in maintaining the stability of the cytoskeleton. However, the expression, function and mechanism of AIF1L in rental cell carcinoma (RCC) is still elusive. Our previously study showed that AIF1L is significantly down-regulated in RCC and lower AIF1L expression was associated with poor prognosis and shorter survival time in RCC patients. Functional study showed that AIF1L inhibited RCC cell viability, colony formation, migration, invasion and sphere formation. KEGG analysis suggested that AIF1L may participate in a variety of signaling pathways, such as the tight junction and cell adhesion molecules pathways. Gene correlation analysis showed that AIF1L was significantly correlated with tumor stem cell markers，such as CXCR4 and CD44. Western blot assay showed that AIF1L suppressed nuclear β-catenin expression, decreased the expression of Vimentin and CD44, and elevated the expression of E-cadherin and ZO-1. Furthermore, the expression of AIF1L was regulated by DNA methylation. Thus, we hypothesize that AIF1L expression is regulated by methylation in its promoter and excert its inhibitory effects on the tumorigenesis and metastasis of RCC through β-catenin nuclear translocation, EMT and tumor cell stemness related pathways. To test this hypothesis, we will first determine the biological function, target gene, and signal pathway of AIF1L in RCC cells as well as in xenograft model. Then, we will investigate the molecular mechanism of epigenetic modification in the regulation of AIF1L expression in RCC cells. Lastly, we will validate the expression level of AIF1L in RCC tumors and evaluate the relationship between AIF1L expression and RCC clinical characteristics in patients with RCC. The results of this study will provide information for identifying new diagnostic biomarkers and therapeutic targets for the treatment of RCC.