miR-205调控p53途径影响肝癌生物学特性及机制研究

miR-205 is related to the tumor development. Until now, there has been no report about miR-205 in human hepatocellular carcinoma. Little is known about how miR-205 is regulated, and the mechanism of miR-205 target regulating tumor development remains obscure. We found that the transcriptional factor Sp1 is related to the expression of miR-205. Furthermore, RNF43 is the target of miR-205 and related to the proliferation of tumor cells. Based on these results, we proposed a hypothesis as followed: "Promoter hypermethylation induced miR-205 down-regulation through reducing Sp1 activity, and the up-regulation of RNF43 promoted the phosphorylation of p53 to regulate the p53 pathway and to make influences on the biological characteristics of hepatocellular carcinoma." Using the technology for bioinformatics, molecular and cellular biology, we will identify the effect of methylation on the miR-205 expression in the development of hepatocellular carcinoma. Meanwhile, we will explore the mechanism that miR-205 regulates p53 pathway through targeting RNF43. To reveal the new mechanism of hepatocellular carcinoma development and discover the new target in treatment of liver cancer, this investigation will provide new ideas for the therapy for hepatocellular carcinoma.

肝癌已居广西恶性肿瘤死亡率首位。miR-205与肿瘤发展相关，其调控机制尚未明了，而在肝癌中目前未见miR-205的相关研究报道。本项目前期研究发现：肝癌中miR-205的表达与转录因子Sp1有关，且miR-205启动子存在甲基化；泛素化连接酶 RNF43是miR-205的靶基因，与细胞增殖有关。据此，推测在肝癌中，高甲基化影响Sp1对miR-205的转录，造成miR-205表达的下降；靶基因RNF43表达上升，泛素化降解p53，进而调控p53途径，影响肝癌细胞的生物特性。本项目拟采用生物信息学、分子细胞生物学等技术，从分子、细胞及临床整体等层次，阐述甲基化影响miR-205的表达在肝癌生长中的作用，探讨miR-205调控p53途径的分子机制，为肝癌靶向治疗提供的新思路。

肝癌居于广西恶性肿瘤死亡率首位。miR-205与肿瘤发展相关，其调控机制及生物学作用尚未明确，而且在肝癌中目前未见miR-205的相关研究报道。本项目主要研究了肝癌中miR-205基因启动子区域甲基化和转录因子Sp1对miR-205表达的影响，miR-205对RNF43的调控，RNF43与p53相互作用，以及miR-205的表达对肝癌生长的影响。结果发现，在肝癌组织中，miR-205表达下降，并且能够抑制细胞的生长。下调的miR-205与miR-205基因启动子的高甲基化具有明显的相关性。miR-205通过结合靶基因RNF43的3’非编码区，直接抑制RNF43蛋白的表达。RNF43参与miR-205调节的细胞增殖与G1/S细胞周期过渡。RNF43能够在活体中逆转miR-205抑制的肿瘤增殖。miR-205通过影响RNF43与p53的相互作用，从而调节细胞周期G1/S的过渡以及肿瘤细胞的生长。转录因子sp1与miR-205的表达具有相关性。本课题从分子、肝癌细胞和临床病人等不同层面系统地证明了甲基化影响miR-205的表达在肝癌生长中的作用，揭示了miR-205靶向RNF43调控p53途径后对肝癌细胞生物学特性的影响。这对进一步揭示 miRNA 在肝癌方面的分子机制，发现新的潜在肝癌治疗靶点，解决广西肝癌高发问题，具有十分重要的意义。研究结果提示，开发miR-205促进剂或RNF43抑制剂可以作为潜在的新的治疗肝癌的药物。