CPSF6介导NOLC1选择性多聚腺苷酸化促进肝细胞癌增殖的机制研究

肝细胞癌（HCC）生长快恶性度高。研究表明mRNA的3’UTR选择性多聚腺苷酸化（APA）异常与HCC进展相关，但其机制尚未明了。我们前期寻找APA调控因子时发现切割与多聚腺苷酸化特异性因子6（CPSF6）在HCC中显著高表达并提示患者预后差。实验研究观察到：CPSF6高表达与其启动子低甲基化相关；在调控CPSF6表达而抑制HCC细胞增殖的实验体系中抑癌基因NOLC1的mRNA发生了APA剪切；沉默NOLC1能逆转CPSF6对HCC增殖的作用。因此，我们提出CPSF6介导NOLC1发生APA剪切，促进HCC快速增殖的科学假设。本项目拟进一步在人体标本、细胞及动物模型中验证CPSF6在HCC快速增殖中的作用并阐述其介导NOLC1发生APA剪切的分子机制；有望获得CPSF6介导APA剪切促进HCC快速增殖的实验证据，为诠释HCC进展的机制和寻找诊治靶点奠定基础。

Hepatocellular carcinoma (HCC) is one of the most prevalent malignancies with high morbidity and mortality worldwide. However, the underlying mechanisms of HCC progression remain elusive. Previous data suggest that Pre-mRNA 3’-end processing are essential for mRNA splicing, mRNA export, translation, and mRNA turnover, which is critical for the regulation of tumor-related genes. Alternative polyadenylation (APA) is highly prevalent in cells for the alternative 3’UTR splicing. Our preliminary data show that cleavage and polyadenylation specificity factor 6 (CPSF6), one of the key components of APA complex, is up-regulated in HCC and associate with poor patient prognosis. In vitro studies suggest that (a) CPSF6-depletion decreases HCC cell proliferation; (b) CPSF6 silencing induced 3’UTR shortening APA events in HCC; (c) Loss of CPSF6 shorten NOLC1 3’UTR which missed binding site of miR-190b; (d) Low promoter methylation activate the expression of CPSF6 in HCC. Based on these findings, we hypothesize that CPSF6-depletion suppress tumor growth via targeting NOLC1. In this study, we aim to determine the expression and clinical significance of CPSF6 in HCC, to disclose the molecular mechanism how NOLC1 was regulated by CPSF6, using a series of biological and immunological experiments in cell and animal models. Our study is likely to provide not only solid evidence that CPSF6 contributes to HCC progression, but also a potential biomarker for HCC clinical diagnosis and treatment.