MicroRNA靶向非小细胞性肺癌干细胞DNA损伤修复途径逆转肺癌耐药、转移的分子机制

Lung cancer especially non-small cell lung cancer is the first important cause of cancer death in the world. Drug resistance and metastasis are major reason for the poor survival of lung cancer patients. Lung cancer stem cell is the essential source of drug resistance, metastasis and recurrence. Recently, it has been demonstrated that DNA damage response (DDR) and DNA repair are a critical barrier for effective chemo- and radio- therapy. We hypothesized that it is possible that the lung cancer drug resistance and metastasis could be reversed via targeting DDR and DNA repair pathways in lung cancer stem cells. In this project, based on the previous studies that miR-758 significantly reduced Rad51 resulting in decreased HR repair, which effectively enhanced the sensitivity of lung cancer cells to chemo- or radio-therapy, we will isolate non-small cell lung cancer stem cells by sorting for the screening of microRNA by microarray following primary cell culture process. We will further study the molecular mechanisms by which microRNAs regulate DDR and DNA repair pathways and their correlation with drug resistance and metastasis. In addition, we will evaluate the role of microRNA in predicting both therapy efficiency and prognosis for lung cancer. Completing this project will clarify the epigenetic mechanisms of lung cancer drug resistance and metastasis from the angle of DDR and DNA repair in lung cancer stem cells, and provide the novel and individually effective therapies for lung cancer patients to reverse drug resistance and metastasis.

肺癌尤其非小细胞性肺癌的死亡率在全球癌症中高居首位，耐药和易转移是肺癌病人生存率差的主要原因。肿瘤干细胞是导致肺癌耐药、转移及复发的重要因素。近来研究证实，DNA损伤反应（DDR）和DNA修复是化放疗取得疗效的重要屏障。因此我们设想靶向肺癌干细胞DDR和DNA修复机制可望克服肺癌耐药和转移。本课题拟在前期研究证明miR-758下调Rad51进而负向调控DNA HR修复增强肺癌细胞对化放疗敏感性的基础上，采用流式细胞仪分选、原代培养及microRNA芯片筛选microRNA，从microRNA角度研究非小细胞性肺癌干细胞DDR和DNA修复机制及其与肺癌耐药、转移的相关性，同时探索microRNA预测肺癌疗效和判断预后的临床意义。课题将从一个新的角度阐明肺癌干细胞DDR和DNA修复的表观遗传调控机制，有望为逆转肺癌耐药、转移提供新的有效策略，为将来肺癌诊治及个性化治疗提供理论依据和实验手段。

非小细胞肺癌发病率高，致死率高，危害严重，罪魁祸首之一是肺癌干细胞。本项目沿着立项主方向和研究总目标，围绕非小细胞肺癌干细胞、miRNA、以及肺泡上皮细胞损伤修复，展开研究。首先围绕非小细胞肺癌干细胞，项目组利用两种非小细胞肺癌细胞株A549及H1299，分选得到CD133+肺癌干细胞亚群，其具有转移、耐药等恶性特征；同时利用非小细胞肺癌临床标本，以及肺癌干细胞，筛选、鉴定了一批肺癌干细胞异常表达的miRNA，包括miR-221/222、miR-34c、miR-208a、miR-501等。进一步利用细胞株、临床标本以及荷瘤动物模型，证明了miR-221/222促进非小细胞肺癌干细胞干性特征、癌细胞增殖能力以及促进肿瘤发生发展等能力。该成果提示miR-221/222可作为抑制肺癌干细胞的一个潜在靶点，具有潜在的临床应用价值。其次，围绕肺上皮细胞损伤及纤维化问题，项目组利用非小细胞肺癌上皮细胞纤维化损伤模型，发现转录因子YY1在肺上皮细胞EMT、转移及纤维化损伤过程中，发挥重要的功能，其表达上调诱导NF-κB从细胞质向细胞核的转位，进而促进下游EMT和纤维化相关基因在表达，导致肺上皮细胞的EMT形态学变化和纤维化损伤。EMT进一步促进了癌细胞转移及恶变。这两方面的研究成果不仅揭示了非编码miRNA调控非小细胞肺癌干细胞的功能及靶点，也发现了肺泡上皮细胞纤维化损伤及侵袭转移的上游调控机制，为抑制非小细胞肺癌干细胞再生肿瘤、预防或者抑制肺上皮细胞纤维化病变和EMT、转移提供了新的潜在靶点，具有进一步研究探索、走向临床转化的价值和潜力。