MALAT1通过下调miR-125b促进膀胱癌进展的分子机制研究

Both microRNAs (miRNA) and long noncoding RNAs (lncRNAs) have been shown to have a critical role in the regulation of cancer development . In the previous work, we found that miR-125b suppresses bladder cancer development via inhibiting long non-coding RNA MALAT1 and other oncogenic genes. It was worth noting that MALAT1 can also repress the expression of mature miR-125b without affecting the levels of pri-miR-125b and pre-miR-125b . This result suggested that MALAT1 may promote the development of bladder cancer by acting as a "molecular sponge" for miR-125b. In order to prove this hypothesis, the following works will be done : firstly, we will investigate the mechanism through which MALAT1 can inhibit miR-125b expression using RNA precipitation and plasmid construction technologies; secondly, we will demonstrate the role of miR-125b in the development of bladder cancer promoted by MALAT1 using RNA activation / interference and miRNA over-expression / knock-down technologies; finally, we will confirm the genes and even pathways affected by MALAT1-induced miR-125b down-regulation using qRT-PCR and western-blot technologies. This project may provide novel mechanism for development of bladder cancer and combinational targets for therapy of this disease.

微小RNA和长链非编码RNA在调控肿瘤进展的过程中均发挥关键作用。我们前期工作发现miR-125b通过下调长链非编码RNA MALAT1和其他多个致癌基因来抑制膀胱癌的进展。值得注意的是，MALAT1也可以抑制miR-125b成熟体的表达，但对其前体的表达没有影响。这提示MALAT1可能通过扮演miR-125b“分子海绵”的角色促进膀胱癌的进展。为验证该假说，我们将开展如下工作：首先通过RNA沉降和质粒构建等技术探讨MALAT1下调miR-125b的分子机制；其次，通过RNA激活/干扰和微小RNA过表达/敲低等技术，揭示miR-125b在MALAT1促进膀胱癌进展中的作用；最后我们将利用qRT-PCR 和 western-blot等技术，确认MALAT1下调miR-125b所引起的基因甚至通路的表达变化。 本项目的实施将可能提供膀胱癌进展的新机制及其治疗的新复合靶点。

微小RNA和长链非编码RNA在调控肿瘤进展的过程中均发挥关键作用。我们前期工作发现miR-125b通过下调长链非编码RNA MALAT1和其他多个致癌基因来抑制膀胱癌的进展。MALAT1也可以抑制miR-125b成熟体的表达，但对其前体的表达没有影响。这提示MALAT1可能通过扮演miR-125b“分子海绵”的角色促进膀胱癌的进展。为验证该假说，我们首先通过RNA沉降和质粒构建等技术探讨MALAT1下调miR-125b的分子机制，发现MALAT1是通过RISC介导的经典途径来降解miR-125b成熟体的表达；其次，通过CRISPR-Cas9、人工miRNA和asRNA等技术，实现了MALAT1的胞内表达激活和抑制，发现MALAT1通过降解miR-125b促进膀胱癌细胞的迁移并抑制其凋亡；最后我们利用qRT-PCR和western-blot等技术，确认MALAT1下调miR-125b引起Bcl-2 和 MMP13 表达升高。本项目首次揭示“MALAT1-miR-125b-Bcl-2 / MMP-13” 轴在膀胱癌进展的关键作用，为膀胱癌的治疗提供了新靶点。