LncRNA MIR17HG在结肠癌奥沙利铂耐药中的作用及分子机制研究

We previously discovered that LncRNA MIR17HG promoted oxaliplatin (L-OHP) resistance in colon cancer (CC), which was significantly associated with regulations of pre/mature-miR17-92 cluster expression and the nuclei translocation of NFκB subunit p65. Interestingly, MIR17HG could be also obviously regulated by NFκB, and there were p65 binding sites in the promoter of MIR17HG. MIR17HG was the host gene of miR17-92 cluster, miR-17 and miR-20a as members of miR17-92 cluster were high expression in CC, what’s more, p65 could regulate the expression of MIR17HG. Based on these findings,we propose that MIR17HG may function as the precursor of miR17-92 cluster, induce the expression of miR17/20a and then activate NFκB signaling pathway increasing the p65 nuclei translocation. Another, p65 may act as the upstream transcriptional factor of MIR17HG inversely, and increase the transcriptional activity of MIR17HG. So, MIR17HG and p65 might form a feedback loop, and then resulte in continued activation of NFκB signaling pathway and L-OHP resistance in CC. In this project, in vivo and in vitro assays will be conducted to confirm the effect of MIR17HG on sensitivity of L-OHP in CC cells. RNA immunoprecipitation (RIP) assay will be used to investigate roles of MIR17HG on regulating the downstream signaling pathway by acting as precursor RNA of miR17 and miR20a. Methods of binding site mutation et al, will be applied to uncover mechanisms of p65 functioning as the upstream transcriptional activated factor of MIR17HG forming a positive feedback loop and resulted in L-OHP resistance of CC, and also confirm the clinical significance of MIR17HG. This project will extend our knowledge on chemoresistance of CC and may provide important theoretical basis for developing novel efficient anti-tumor drug with multi-targets. It will be beneficial to make the individualized and precising treatment strategies and improve the efficacy of chemotherapy.

前期实验发现LncRNA MIR17HG在结肠癌奥铂耐药细胞中表达上调，能促进miR17-92簇中miR17、miR20a前体和成熟体表达，以及p65入核；而MIR17HG表达亦受p65调节，预测其启动子区存在p65结合位点。MIR17HG是调控miR17-92簇主基因，而p65能增强目的基因转录活性。由此推测，MIR17HG可能通过直接调控miR17、miR20a，促使p65入核；而反过来p65作为上游调节因子，增强MIR17HG转录，两者互为因果，形成正反馈环路及促进耐药；联合检测MIR17HG及相关分子可能预测化疗疗效。本项目将验证MIR17HG对结肠癌奥铂耐药的影响，探讨其直接调控miR17-92簇的下游分子信号，以及p65正反馈调控MIR17HG转录和促进耐药的分子机制，并阐明临床意义。本项目将揭示MIR17HG促进奥铂耐药的机制，构建多分子联检模型，有利于临床个体化的精准治疗。

结肠癌化疗耐药是制约临床诊疗效果的关键问题，严重影响着结肠癌患者的预后。非编码RNA是一类具有广泛生物学功能的分子，在肿瘤的发生、发展、耐药、复发中扮演着重要角色。本研究首次发现长链非编码RNA MIR17HG与结肠癌奥沙利铂耐药紧密相关。通过分子生物学实验和动物实验，我们发现MIR17HG具有促进结肠癌奥沙利铂耐药的作用，这一过程与NF-kB通路的活化有关。MIR17HG通过miR-17来激活NF-kB信号通路，进而正反馈促进自身转录，持续诱导化疗耐药的发生。结肠癌化疗耐药常常与后续的复发转移相接续。我们同样发现，MIR17HG也具有促进结肠癌肝转移的功能。机制上，MIR17HG通过吸附miR-138-5p来促进糖酵解关键酶HK1的表达，进而增强了肿瘤细胞的迁移和侵袭能力。这些研究结果为理解结肠癌的恶性进展提供了全新的视野，给结肠癌化疗增敏提供了潜在靶标，为后续深入探究结肠癌发病机理和开发新型治疗方案提供了前期理论基础。项目研究成果在Oncogene等期刊发表论文7篇。