miR-18ab调控ATM信号通路在CD133+肺癌细胞放疗抗拒中的分子作用机制

Lung cancer stem cells cause radiotherapy resistance. Thus, investigating the molecular methanism underlying the radiotherapy resistance contributes significantly to reversing radiotherapy resistance of lung cancer cells. We have previously observed that both miR-18a and miR-18b are lowly expressed in CD133+ radiotherapy - resistant lung cancer cells.Two miRNAs regulate the ATM signaling pathway and may be an important mechanism for radiotherapy resistance of CD133+ stem cell-like lung cancer cells. In this study, we will first comfirm the relationship between miR-18ab and ATM and CD133+ lung cancer cells; and then, we will structurally and functionally verify the authenticity of the regulation of ATM signaling pathway by miR-18ab; and next, by using CD133+ and CD133- lung cancer cells, we will design two-direction experiments to verify the key role of ATM signaling pathway in miR-18ab-mediated radiotherapy resistance of CD133+ lung cancer cells; and finally, we will validate the clinicopathological relationship between miR-18ab and radiotherapy resistance of CD133+ lung cancer cells in clinical specimens.This study provides new insights into radiation biology and new approaches to gene radiotherapy, and will be of theoretical significance and have vast vistas for clinical applications with regard to clarifying the molecular mechanism underlying the radiotherapy resistance of lung cancer stem cells.

肺癌干细胞是放射抗拒的根源，探讨其放疗抗拒的分子机制，对于逆转肺癌细胞放疗耐受具有重要意义。前期研究发现，CD133+放疗抗拒肺癌细胞中miR-18a和miR-18b低表达，它们调控ATM信号通路很可能是CD133+干细胞样肺癌细胞放疗抗拒的重要机制。本项目拟首先在细胞学和组织学上确证miR-18ab及ATM与CD133+肺癌细胞的关系，并从结构学和功能学上验证miR-18ab调控ATM信号通路的真实性；然后，分别以CD133+肺癌细胞和CD133-肺癌细胞为实验对象，设计正向实验和反向实验，正反两方面验证ATM信号通路在miR-18ab介导CD133+肺癌细胞放疗抗拒中的关键作用；最后，从临床标本中验证miR-18ab与CD133+肺癌细胞放疗抗拒的临床病理关系。该研究既是肿瘤放射生物学的新理念，也是基因-放射治疗的新策略，对于阐明肺癌干细胞放疗抗拒的分子机制有重要的理论意义和应用前景。

肺癌干细胞是放射抗拒的根源，探讨其放疗抗拒的分子机制，对于逆转肺癌细胞放疗耐受具有重要意义。本研究发现：CD133+肺癌细胞的克隆形成能力高于CD133-肺癌细胞，具有干细胞特性；CD133+肺癌细胞有较强的放射线抗拒性，其中miR-18a低表达；miR-18a过表达可增强CD133+肺癌细胞的放射线敏感性，D0、Dq、SF2等放射生物学参数均下降；miR-18a与两种DNA损伤修复基因ATM和HIF-1α的3’-UTR相结合，miR-18a过表达可下调肺癌细胞中ATM和HIF-1α的蛋白水平；在辐照处理时，miR-18a稳定过表达组的裸鼠移植瘤的肿瘤体积小、生长速度慢，移植瘤组织中miR-18a水平较高，ATM和HIF-1α蛋白水平较低；比较54例接受单纯放疗的IV期NSCLC患者放疗前血浆miR-18a水平，15例放疗有效者（CR+PR）miR-18a表达显著高于39例放疗耐受者（SD+PD）；miR-18a（cutoff 2.28）预测晚期NSCLC放疗疗效的敏感性和特异性分别为87%和95%。本研究结论：CD133+肺癌细胞低表达miR-18a，是其放射线抗拒的重要机制；miR-18a过表达，可双重下调DNA损伤修复基因ATM和HIF-1α，增强CD133+肺癌细胞放射敏感性；血浆miR-18a可作为预测NSCLC患者放疗敏感性的生物标志物。本研究结果是肿瘤放射生物学的新发现，具有重要的理论意义和应用前景。