研究抑制干细胞相关基因HIWI以及与肺癌靶向药物联合使用在基因突变肺癌治疗中的作用

Lung cancer is a world-wide leading cause of cancer related death. Lung cancer also has a very high incidence rate, and recently this rate is rapidly increasing. The initiation of precision medicine in the world including China provides a great benefit for lung adenocarcinoma patients who have known epidermal growth factor receptors (EGFR) mutations or ALK gene rearrangement. Gene-informed personalized medicine has significantly prolonged progression-free survival and improved the life quality of lung cancer patients. However, the formation of drug resistance and tumor relapse results in long term treatment failure, which greatly hindered the small molecule based targeted therapy in lung cancer. Due to the high tumorigenic ability and drug resistant potentials, cancer stem cells represent an important source for tumor formation and relapse. Novel agents and therapeutic strategies to eliminate cancer stem cells are in development with the hope to overcome drug resistance. Stem cell related gene HIWI has been shown overexpressed in many types of cancer and its expression is related to many cancer stem cell like characteristics. HIWI inhibition greatly prevent tumor formation in xenograft mouse model and has great potential to serve as a cancer drug target. However, there is no direct evidence for HIWI function in the initiation of cancer, drug response and tumor relapse from mice in vivo having normal immune system. This research will 1) investigate the role of HIWI in EGFR and ALK mutated lung cancer cell lines and xenograft mouse models; 2) study the effect of MIWI, the mouse counterpart of HIWI, in mutant EGFR-driven mouse models by gene knock out; 3) study the effect of HIWI inhibition on drug response in cell lines and in mouse model, evaluate the potential of using HIWI inhibition alone or in combination with EGFR based targeted therapies in these models; 4) analyze whether the function of HIWI is piRNA related. This study will provide direct evidence for the role of HIWI in tumor formation and drug resistance, and potentially can provide a novel therapeutic method to overcome drug resistance.

肺癌是我国乃至世界上发病率高、致死率最高的癌症，且近年来发病率上升迅速，严重影响了国家经济建设和社会的发展。 国家精准医疗计划的推行对具有基因突变肺癌的患者进行个体化靶向治疗可显著延长患者无病生存期，提高生存质量。然而，肿瘤复发和耐药性的产生是导致治疗失败，阻碍靶向治疗前进的绊脚石。 肿瘤干细胞被认为是肿瘤复发的根源。肿瘤治疗中彻底清除肿瘤干细胞有望能克服肿瘤耐药性的产生。近年来研究显示干细胞相关基因HIWI在多种肿瘤中异常高表达，并与肿瘤的发生和干细胞样特性相关，是肿瘤治疗的一个潜在作用靶点。然而目前已有的相关报道均来自于肿瘤细胞株和小鼠移植瘤模型，尚无体内数据支持。 本课题拟采用基因突变肺癌细胞株和转基因小鼠模型来研究HIWI在基因突变肺癌发生发展中的作用，并用这些模型研究HIWI阻断与肺癌靶向药物联合使用对治疗效果的影响和分子机制。本课题可潜在地为肿瘤治疗提供新方法。

对ALK和EGFR基因突变的肺癌采用靶向治疗大大提升了患者的治疗效果， 但是肿瘤复发对靶向药物产生的耐药现象极大限制了药物的长期疗效。本研究的主要目的就是发展新策略来克服肿瘤对靶向药的耐药现象。 靶向肿瘤干细胞从理论上讲是一种潜在的方法可以治疗癌症和克服耐药。本文首先探索了干细胞相关基因HIWI在ALK和EGFR突变阳性肺癌中的作用。结果显示敲除或敲低干细胞相关基因HIWI不能够杀死肺癌细胞；此外敲除或敲低HIWI基因与靶向药物联合使用也不能很好地杀灭ALK和EGFR突变的非小细胞肺癌细胞。我们通过蛋白降解技术开发了ALK蛋白降解剂SIAIS117，并在ALK阳性肿瘤细胞中进行了活性研究，结果发现SIAIS117对ALK阳性肿瘤细胞有很好的杀伤，并在克服靶向药物的耐药方面显示了巨大的潜力：与抑制剂相比它不仅可以更好地抑制ALK融合突变阳性的间变性淋巴瘤和肺癌细胞的增殖，而且对具有ALK融合G1202R耐药突变的细胞也具有更好的杀伤抑制活性。此外，该降解剂还在药物生理剂量允许的范围内对小细胞肺癌细胞有一定的杀伤活性，对由向小细胞肺癌转化造成的耐药现象潜在地具有抵御作用。本项研究使用崭新的蛋白降解技术对克服肺癌的耐药现象进行了初步探索，结果展现了蛋白降解剂与抑制剂相比活性上的优势，对后续开发蛋白降解药物成为抗肿瘤的新策略具有开创性影响。