RBFOX3靶向上调hTERT促进结直肠癌生长的作用机制和临床意义

hTERT is the hallmarker of tumorigenesis. It is of importance to discover and identify regulatory mechanisms of hTERT. In our preliminary studies, we used a new pull-down system for the identification of DNA-binding proteins and discovered and identified RBFOX3 as an hTERT promoter binding protein in colon cancer cells. We also found that RBFOX3 could up-regulate hTERT transcriptional activity and modulate tumor cell growth, migration and apoptosis. However, the mechanisms by which RBFOX3 regulates hTERT　expression and the role and clinical significance of RBFOX3 in colon tumorigenesis remain unclear. In this study, we will further study the regulation of RBFOX3 on hTERT expression, telomerase activity, telomere length, cell growth and apoptosis, tumor formation, and the related signaling pathway in colon cancer cell lines and animal models, thereby identifying the biological functions and molecular mechanisms of RBFOX3. Moreover, we will also analyze the expression of RBFOX3 and hTERT in tumor tissues and evaluate their correlation with lung cancer development, clinical stage, metastasis and prognosis, identifying the clinical significance of RBFOX3 and hTERT. This program will provide new understanding for revealing the novel mechanisms involved in hTERT expression regulation and colon carcinogenesis, and also provide the theoretical and experimental basis for the development of the RBFOX3/hTERT signaling pathway as a new therapeutic target for cancers.

hTERT高表达是肿瘤发生发展的风向指标，深入研究其调控机制意义重大。前期研究我们用新的DNA结合蛋白垂钓鉴定系统，在结直肠癌细胞中发现确定RBFOX3为hTERT启动子结合蛋白，并证明RBFOX3可上调hTERT转录活性，调控细胞生长、迁移和凋亡。但RBFOX3如何调控hTERT表达及其在肿瘤发生发展过程中的作用机制和临床意义，目前尚不清楚。本项目拟在结直肠癌细胞和动物模型中，进一步研究RBFOX对hTERT表达、端粒酶活性、端粒长度，细胞生长和凋亡、肿瘤形成、及相关信号通路的调控，进而明确RBFOX3的生物学功能和作用机制。另外，分析RBFOX3和hTERT在肿瘤组织标本中的表达，评估它们与结直肠癌发生、分期、转移、预后等的相关性，明确其临床意义。本项目将为揭示hTERT表达调控和结直肠癌发病机制提供新认识，也为确立RBFOX3/hTERT信号通路作为肿瘤治疗新靶点提供理论和实验依据。

本研究利用DNA结合蛋白垂钓系统及蛋白质谱技术，在结直肠癌和肝癌细胞中发现确定RBFOX3为hTERT启动子结合蛋白。RBFOX3可上调hTERT基因转录和表达，调控结直肠癌和肝癌细胞增殖、迁移、侵袭、凋亡和细胞周期进程，进而促进肿瘤生长和转移。RBFOX3可与AP-2β相互作用，协同调控hTERT基因表达和功能活性。RBFOX3与hTERT在结直肠癌和肝癌肿瘤组织中高表达并呈正相关，与病人不良预后相关。RBFOX3也通过调控PI3K和MAPK信号通路、细胞上皮间质转化 (EMT)和细胞色素c/Caspase凋亡通路，影响肿瘤细胞的生长转移以及对化疗药物5-FU的敏感性。该研究为揭示肿瘤发病机制提供新认识，也为确立RBFOX3/hTERT信号通路作为肿瘤治疗新靶点提供科学依据。相关成果发表在“Theranostics”。另外，在肝癌细胞中，证明BPTF通过调控hTERT表达和肿瘤干细胞潜能，进而促进肿瘤的生长，揭示BPTF/hTERT信号轴是一个潜在的治疗新靶点。相关成果发表在“Redox Biology”。在白血病细胞中，发现褪黑激素通过抑制RBFOX3/hTERT通路，介导了褪黑素的抗白血病作用。相关成果发表在“Cancer Letters”。此外，在三阴乳腺癌细胞中，发现核磷酸蛋白(NPM1)特异性结合于PD-L1启动子上。NPM1可上调PD-L1转录和表达，促进T细胞活性。敲低NPM1可抑制小鼠模型三阴乳腺癌生长及转移，促进肿瘤间质中T细胞浸润，激活抗肿瘤免疫。NPM1与PARP1蛋白质存在相互作用，PARP1可抑制PD-L1转录和表达，PD-L1单抗联合PARP1抑制剂Olaparib对三阴乳腺癌具有更好的疗效。相关成果发表在“Nature Communications”。在该项目基金和其它基金的支持下，共发表SCI科学文章 25篇，培养5名博士研究生顺利毕业。