APE1调控线粒体自噬介导非小细胞肺癌铂类耐药及其分子机制的研究

Lung cancer is the most common malignant tumor in the world, 80% of which is non-small cell lung cancer (NSCLC), platinum resistance is the main cause of poor chemotherapy curative effect in NSCLC patients. Apurinic apyrimidinic endonuclease (APE1) with double functions as AP endonuclease and Reduction-oxidation. In previous studies, we found that, after theoxidative stress, the translocation of APE1 to mitochondria could significantly improve mitochondrial membrane permeability, inhibit cell apoptosis and repair the damaged mitochondria. When mitochondrial severely damaged beyond repair, mitochondrial membrane potential was reduced, and Pink1/Parkin-mediated mitophagy selectively removed damaged mitochondria. Mitochondrial APE1 and mitophagy played an important role in keeping the quality and quantity of mitochondria, therefore, for the first time, we raised a hypothesis that mitochondrial APE1 may through the mitochondrial membrane potential and Pink1/Parkin level to regulate mitophagy, further promotes platinum resistance in NSCLC chemotherapy. This project will use RNA inference, positioning and dominant negative mutation strategy to reveal the molecular mechanism of mitochondrial APE1 regulate the mitophagy, in order to provide new strategy to overcome the clinical platinum resistance in NSCLC chemotherapy.

肺癌是世界上最常见的恶性肿瘤，其中80%为非小细胞肺癌（non-small cell lung cancer, NSCLC），铂类耐药是导致总体疗效较差的主要原因。脱嘌呤脱嘧啶核酸内切酶（APE1）具有AP核酸内切酶和氧化还原双功能，前期我们发现氧化应激状态下APE1发生线粒体转位，可显著改善线粒体膜的通透性、抑制凋亡、修复受损的线粒体。线粒体受损严重无法修复时，线粒体膜电位降低，经Pink1/Parkin激活线粒体自噬，选择性地清除受损线粒体。鉴于线粒体APE1与线粒体自噬在保持线粒体质量和数量稳定中发挥的重要作用，因此，我们首次提出假设：线粒体APE1通过线粒体膜电位-Pink1/Parkin水平调控线粒体自噬，导致NSCLC铂类耐药。本项目拟通过干扰表达、线粒体定位及显性负突变等策略揭示线粒体APE1调控线粒体自噬的分子机制，为临床解决非小细胞肺癌铂类耐药问题提供新的思路。

近年来，靶向、免疫等治疗在非小细胞肺癌治疗中发挥了重要作用，但化疗仍不可取代，不管是单独化疗还是联合靶向、免疫等治疗均有很好的疗效。铂类是化疗的基石，但铂类耐药往往是肺癌治疗失败的的主要障碍，其耐药机制尚未完全阐明。在本青年基金项目的资助下，研究主要阐明了线粒体 APE1 与非小细胞肺癌铂类耐药的相关性及其产生耐药的分子机制。我们发现耐药A549细胞系(A549/DDP)和顺铂敏感A549细胞系相比，线粒体APE1显著升高；诱导线粒体APE1升高后，A549细胞增加顺铂耐药性；si-APE1敲低APE1的表达后，A549/DDP细胞增加了顺铂敏感性。本实验首次发现线粒体APE1可能是通过线粒体膜电位- Pink1/Parkin 途径，激活线粒体自噬通路，导致顺铂耐药。该通路中的蛋白特别是线粒体APE1可做为潜在靶点，以增加顺铂敏感性，提高化疗疗效。