LncRNA RASSF8-AS1募集m6A“阅读器”IGF2BP1调控RASSF8表达激活Wnt/β-catenin信号通路促进结直肠癌恶性演进的分子机制

转移是结直肠癌患者死亡的主要原因，虽得到广泛关注，但其具体的分子机制仍有待深入研究。我们前期研究发现：LncRNA RASSF8-AS1在结直肠癌中高表达可促进肿瘤的增殖、侵袭及EMT；RASSF8-AS1能募集m6A“阅读器”IGF2BP1并正向调控靶基因RASSF8的表达；RASSF8过表达在促进肿瘤增殖和侵袭的同时，可协助β-catenin入核激活Wnt信号通路，由此提出“RASSF8-AS1通过RASSF8激活Wnt/β-catenin信号通路促进结直肠癌恶性演进”的科学假说。本课题拟在前期基础上，利用分子生物学、细胞生物学以及实验动物学等一系列体内、体外实验手段系统研究RASSF8-AS1在结直肠癌增殖及转移中的作用，并深入揭示其调控靶基因RASSF8表达及激活Wnt/β-catenin信号通路的确切分子机制。本课题的顺利完成有望为结直肠癌转移的预防和治疗提供新靶点和新思路。

Metastasis is the main cause of death in the patients with colorectal cancer (CRC). Although CRC metastasis recently attracts extensive attention, its molecular mechanisms remain to be determined. The results of our preliminary experiments showed that the expression of the long non-coding RNA (LncRNA) RASSF8-AS1 was upregulated in CRC tissues and cell lines. RASSF8-AS1 depletion could inhibit the proliferation and invasiveness of CRC cells and repress epithelial-to-mesenchymal transition (EMT). RASSF8-AS1 could recruit insulin like growth factor 2 mRNA binding protein 1 (IGF2BP1), a N6-methyladenosine (m6A) “reader”, thereby promoting its sense-cognate gene RASSF8 mRNA and protein expression. The RASSF8 overexpression in cell nucleus promoted cell proliferation and invasiveness and facilitated β-catnenin import into the nucleus activating Wnt/β-catnenin signaling. Therefore, basing on these important new findings, we propose a hypothesis that RASSF8-AS1 promotes CRC progression by recruiting m6A-reader IGF2BP1 to regulate RASSF8 expression and activate Wnt/β-catenin signaling. In this study, we will further evaluate the roles and clinical significance of RASSF8-AS1 and RASSF8 in the development and progression of CRC in vitro and in vivo through gain- and loss- of function models. Furthermore, we will explore the regulation mechanisms by which RASSF8-AS1 promotes RASSF8 expression in CRC by RNA pull-down, Mass spectrometry, RNA immunoprecipitaiton (RIP) and gene mutations. We will investigate the molecular mechanisms by which RASSF8-AS1/RASSF8 activates Wnt/β-catenin signaling contributing to CRC progression using Co-IP, GST-pull down and gene mutations. The research will contribute to reveal the molecular mechanisms of CRC progression, and will provide novel targets and strategies for the preventing and therapy of CRC metastasis.