miR-146a/LIN28/Let-7反馈轴调节肺癌干细胞自我更新能力的作用及机制研究

肺癌发病率高预后差，降低肺癌干细胞比例对实现肺癌临床治愈具有重要意义。前期我们发现miR-146a可降低肺癌干细胞比例，其过表达伴随Wnt通路抑制因子Let-7的升高，而miR-146a在肺癌干细胞自我更新过程中的作用及其与Wnt通路的关系未见报道。前期生物信息学预测miR-146a可与LIN28A非编码区结合；肺癌细胞中Wnt通路激活对Let-7起海绵调性节作用，因此我们提出假设，miR-146a通过靶向抑制LIN28表达而上调干细胞内成熟Let-7表达，减弱Wnt通路活性及其维持的肺癌干细胞自我更新；miR-146a逆转肺癌干细胞中Wnt激活剂对Let-7的海绵性调节作用。课题拟通过荧光素酶报告实验、荧光探针等方法阐明miR-146a通过上调Let-7而阻断干细胞中Wnt通路的激活，为进一步以非编码RNA为手段而靶向Wnt通路，抑制肺癌干细胞的自我更新能力提供新思路、新方法和理论依据。

The incidence of Lung cancer is much higher than that of other malignancies, and lung cancer always results in poorer prognosis. Decreasing the ratio of lung cancer stem cells (LCSCs) is of great value to achieve clinical cure of patients with lung cancer. In previous studies, we found that miR-146a decreased the ratio of LCSCs, with increased Let-7 level, of which we have identified the suppressive roles exhibiting on Wnt signaling activation; however, the roles of miR-146a in the procss of self-renewal of LCSCs, and the relationship with Wnt signaling, which has been tentatively applied in preclinical trials, is still unclear. We predicted the potential binding site between the 3’UTR of LIN28A and miR-146a, and also found that Wnt activator may funcion as Let-7 sponges in LCSCs, with the results that Let-7 retained the same level, when its downstream genes increased significantly. Based on these results, we hypothesized that miR-146a suppresses the self-renewal of lung caner stem cells through targeting and degrading LIN28A, which help to increase Let-7 consequently, with Wnt signaling inactivation. Besides, the overexpressed miR-146a reversed the sponges regulation of Wnt activator on Let-7. To prove this hypothesis in this project, we plan to explore the functions and mechanisms of miR-146a in Let-7 induction of Wnt signaling blockade, by using stem cells isolation and identification, luc-assay, western blot and fluorescent probe technique real time PCR. The results of this study will help to target and block the Wnt signaling sustaining of self-renewal of cancer stem cells via non-coding RNAs, and pave the way to the consequent clinical cure of lung cancer with basis of new thoughts, new methods and theoretical foundation.