lncRNA-MEG3调控MET表达介导肝细胞癌索拉非尼耐药的作用机制研究

Although sorafenib has been used as the first-line choice in targeting treatment of hepatocellular carcinoma (HCC), its efficiency is limited because of drug resistance. Our previous studies have demonstrated that the MET expression is associated with sorafenib resistance in HCC, however, the molecular mechanisms remains unclear. Recently, we detected the differential expressions of mRNAs and long noncoding RNAs(lncRNAs) between sorafenib-resistant HCC tissues and sorafenib-sensitive HCC tissues by lncRNAs microarray technology. Results showed that high-expression of MET is associated with reduced lncRNA-MEG3 expression in sorafenib-resistant HCC tissues. Further RNA pull-down experiments suggested that lncRNA-MEG3 combined with MET. Over-expression of lncRNA-MEG3 inhibits the MET expression and inhibits the proliferation and invasion of HCC cells. Thus, we speculate that lncRNA-MEG3 combines with MET and inhibits its expression, then inhibits its downstream pathways that associated with HCC viability, and finally reduces the treatmental efficiency of sorafenib to HCC. The current study will confirm that lncRNA-MEG3 regulates MET expression and prompts sorafenib resistance in hepatocellular carcinoma. Furthermore, the efficency of combined treatmet of sorafenib and lncRNA-MEG3 over-expression will also be determined. This study will facilitate to clarify the novel mechanism of sorafenib resistance in the treatment of HCC, thus provide more scientific basis for the targeting therapy of HCC.

索拉非尼是治疗肝癌的一线靶向药物，但是因为肝癌对其耐药而疗效远不理想。我们前期研究表明，肝癌组织中MET表达与索拉非尼耐药相关，但具体机制不清。近期我们通过基因芯片筛选索拉非尼耐药和敏感肝癌组织中差异表达的mRNA和lncRNA，发现耐药肝癌组织中MET高表达的同时伴有lncRNA-MEG3(MEG3) 低表达；RNA pull-down实验提示MEG3可能与MET直接结合；在肝癌细胞中过表达MEG3可抑制MET表达，并抑制肝癌细胞增殖迁移。由此，我们推测MEG3通过与MET结合，调控MET及其下游肝癌增殖相关通路，从而影响肝癌对索拉非尼的敏感性。本项目拟进一步从分子、细胞和动物水平，通过RIP、缺失定位等实验方法证实MEG3调控MET表达介导肝癌索拉非尼耐药的具体机制，并探讨索拉非尼联合MEG3过表达对克服肝癌靶向耐药的可行性。项目的开展有望为肝癌靶向治疗耐药机制的阐明提供新的科学依据。

肝细胞癌（hepatocelluar carcinoma, HCC）是最常见的消化系统恶性肿瘤之一。近年来，外科切除、移植、局部消融和全身治疗等多种HCC治疗手段的不断发展和综合应用，在一定程度上提高了HCC的治疗效果。但是，由于HCC早期无明显症状，多数患者确诊时已属中晚期，导致HCC总体疗效和预后仍不理想。而分子靶向药物的临床应用，为改善HCC患者的预后带来了新的希望。索拉非尼是治疗HCC的一线靶向药物。临床研究及实践表明，索拉非尼可延长晚期肝癌患者的总生存期。但是，目前索拉非尼治疗HCC的总体疗效仍有限，部分HCC患者在治疗初期即表现为索拉非尼耐药。即使治疗初期对索拉非尼敏感的患者中，也有部分患者在治疗过程中逐渐产生耐药，从而致使预后不佳。因此，阐明HCC索拉非尼耐药的具体分子机制，对于提高HCC靶向治疗效果，改善患者预后具有重要的意义。本项目研究发现，肝癌组织中MET表达与索拉非尼耐药相关；进一步通过基因芯片筛选索拉非尼耐药和敏感肝癌组织中差异表达的mRNA和lncRNA，发现耐药肝癌组织中MET高表达的同时伴有lncRNA-MEG3 低表达；RNA pull-down实验提示lncRNA-MEG3可与MET直接结合；在肝癌细胞中过表达lncRNA-MEG3可抑制MET表达，并抑制肝癌细胞增殖迁移。本项目明确了索拉非尼联合lncRNA MEG3过表达对克服HCC索拉非尼耐药的有效性，从而为进一步提高HCC靶向治疗效果提供新的科学依据。同时，本项目还证实了非编码RNA miR-1226-3p可通过下调编码基因DUSP4表达水平促进HCC对索拉非尼治疗的敏感性。项目的开展为肝癌靶向治疗耐药机制的阐明提供了新的科学依据和实验参考。