TFAP4新靶MECP2通过IGF1R-AKT和Notch1-MMPs通路促进口腔鳞状细胞癌进展

转录因子TFAP4和表观调节因子MECP2在肿瘤进展中发挥着重要作用。我们前期工作与生物信息学分析表明口腔鳞状细胞癌中TFAP4与MECP2表达呈正相关；TFAP4促进MECP2表达；TFAP4与MECP2启动子区结合，MECP2与IGF1R和Notch1启动子区甲基化的CpG位点结合，提出TFAP4靶向调控MECP2，进而调节IGF1R-PI3K-AKT和Notch1-Hes1/MMPs通路影响口腔鳞状细胞癌进展。本研究拟分析TFAP4和MECP2表达的临床意义；应用ChIP-Seq、ChIP-RT-PCR、mRNA-Seq、DNA-pull-down、报告基因等研究TFAP4-MECP2-IGF1R/Notch1轴分子间的靶向调控关系；细胞生物学技术检测TFAP4、MECP2、IGF1R、Notch1等生物学功能；建立荷瘤裸鼠模型验证，揭示其在口腔鳞状细胞癌中的作用及表观调控分子机制。

Transcription factor TFAP4 (Transcription factor activating enhancer binding protein 4) and epigenetic regulator MECP2 (Methyl-CpG binding protein 2) play important roles in tumor progression. Our previous research and bioinformatics analysis showed that TFAP4 expression was positively correlated with MECP2 expression in oral squamous cell carcinoma. Silencing TFAP4 down-regulated MECP2 expression, while overexpression TFAP4 up-regulated MECP2 expression. TFAP4 promoted MECP2 transcription by binding to the MECP2 promoter region. MECP2 facilitated IGF1R and Notch1 transcription through binding to the methylation CpG sites of their promoter region. Silencing TFAP4 inhibited oral squamous cell carcinoma cell proliferation, cell cycle G1/G0-S phases transition, invasion and migration, induced apopotosis. At the same time, silencing MECP2 also suppressed oral squamous cell carcinoma cell proliferation, cell cycle transition, invasion and migration, promoted apopotosis. Therefore, we propose that TFAP4 targets MECP2 to regulate the IGF1R-PI3K-Akt and Notch1-Hes1/MMPs pathways to influence oral squamous cell carcinoma progression. In the present study, firstly, the clinical significance of TFAP4 and MECP2 expression in oral squamous cell carcinoma is observed using quantitive real-time PCR analysis, immunohistochemical and immunoblotting. Then, ChIP-seq, ChIP-RT-PCR, mRNA-seq, DNA-pull-down and reporter assay are used to explore the targeting mechanism of TFAP4 to MECP2, and MECP2 to IGF1R/Notch1. Next, the roles of TFAP4, MECP2, IGF1R and Notch1 in the cell proliferation, cell cycle, apoptosis, invasion, and migration of oral squamous cell carcinoma are studied by using MTT, colony forming experiment, flow cytometry, transwell assay, wound healing. Finally, the influences of TFAP4-MeCP2-IGF1R/Notch1 axis are explored in vivo using nude mice. We aim to explore the roles of TFAP4-MeCP2-IGF1R/Notch1 axis and the epigenetic regulation mechanism in oral squamous cell carcinoma development and progression, which will provide a new perspective on the pathogenesis and progression of oral squamous cell carcinoma.