XRCC1基因多态与晚期NSCLC铂类化疗疗效关联分析及其机制研究

Chemotherapy resistance is the major obstacle in platinum-based chemotherapy on advanced non-small cell lung cancer (NSCLC) patients.It has been reported that gene polymorphisms might predict clinical outcome (response rate and overall survival), but the reported results are not consistent and lack mechanism studies. As a result, we conducted a system review and a meta-analysis, and found that after excluding low quality studies, response rate became no association with a common polymorphism of XRCC1 gene (specify the site), one of the mainly platinum-related genes. Moreover, we found there was also no association between this common polymorphism and clinical outcome in platinum-based chemotherapy treated Chinese NSCLC patients.Our futher studies showed that a tagSNP, 5'UTR 1678G/A, was associated with clinical outcome. Interestingly, this SNP influences XRCC1 expression.In this project, we will re-sequence the vicinity of this tagSNP to find out all associated genetic polymorphisms.In addition, we will do a multiple competitive RT-PCR method for detcting XRCC1 copy number variants.Next, we will make different variant expressing models in NSCLC resistant cells and tumor-burdened models to identify the casual variants and reveal the resistance mechanism. These findings will aid to choice the platinum chemotherapy on advanced NSCLC patients, faclilitating adavances in personailized medicine.

铂类化疗为晚期非小细胞肺癌（NSCLC）主要疗法，但只对部分患者有效。已有研究表明XRCC1与铂类代谢密切相关，其外显子上的非同义突变Arg399Gln可预测疗效，但不同研究间存在争议。我们通过对文献Meta分析发现，排除低质量文献后Arg399Gln不再与疗效相关（Wu et al., Clinical Cancer Research，2012）,并在随后进行的1004例NSCLC铂类化疗病例分析中得到验证。我们进一步利用标签SNP对该1004例患者进行关联分析，发现XRCC1基因5'UTR 1678G/A与疗效显著相关，且该位点变异影响XRCC1表达。本项目拟对该基因外显子及调控区进行全测序，竞争性多重PCR检测拷贝数变异，发现影响疗效的关键多态；并利用NSCLC铂类耐药细胞株及荷瘤动物模型对关键多态的功能筛查、鉴定，阐明铂类化疗相关分子机制，为晚期NSCLC铂类治疗提供新的预测因子。

肺癌是我国发病率和死亡率最高的恶性肿瘤，57%的肺癌患者发现时已远处转移，其五年生存率低于10%。铂类化疗为晚期非小细胞肺癌（NSCLC）主要疗法，但存在耐药反应和毒性反应的个体差异。因此，目前亟需预测肺癌风险、疗效和毒性反应的方法。本课题组收集974例肺癌患者和1005例健康人群，发现代谢相关基因中TYMS基因rs3819102 T>C 显著增加肺癌风险，MTHFR基因rs1801133对肺癌风险影响不明显；炎症标志物CRP基因rs2808630、DNA修复基因GTF2H1基因rs3802967与吸烟共同影响肺癌易感性。1004例铂类化疗NSCLC患者中，对XRCC1基因13个SNP位点进行分型，发现 5’UTR 1678G/A位点与NSCLC铂类化疗疗效差相关；XRCC1上下游及外显子再测序，找到了新的潜在功能位点。TGFBeta通路157个SNP进行分型，发现TGFBR2基因rs3773663与NSCLC铂类化疗疗效好呈正相关；使用机器学习中Extreme Gradient Boosting方法有效地区分了短生存组与长生存组。本研究探索了SNP在肺癌发生发展及化疗耐药中作用，建立了新的预测肺癌风险、疗效和生存的模型，为肺癌患者早期发现及治疗提供指导。