ABCC2单核苷酸多态性预测胃癌新辅助化疗疗效的分子生物学基础

Perioperative chemotherapy combined with D2 radical gastrectomy is the multimodality treatment most suitable for the Chinese gastric cancer patients who are mostly in local advanced stage, the efficacy of neoadjuvant chemotherapy is significantly correlated to the prognosis of the gastric cancer patients who receive this combined therapeutic model. Considering the overall unsatisfactory efficacy of the preoperative chemotherapy, early screening of the treatment resistant patients is an urgent problem to be settled. .In our preliminary study, we investigate the 33 SNPs in 103 gastric cancer patients peripheral white blood cells DNA through snapshot analysis and DNA sequencing, all these SNPs were reported to be related to efficacy of 5Fu and platin, results indicate that ABCC2 gene rs717620 locus GG genotype is correlated to chemotherapy inefficiency and worse prognosis. Our research aims to confirm the correlation through detection in larger scale of clinical cohort, and then explore the underlying molecular biological mechanism through construction of ABCC2 knocked down, overexpression cell line and construction of ABCC2 knocked down mouse model. In the perspectives of clinical practice, the ABCC2 gene rs717620 SNP may help us discriminate the patients with drug resistance, spare the unnecessary chemotherapy and carry out operation in time, so as to improve patients prognosis to maximum extent.

围手术期化疗联合D2根治手术的综合治疗模式是最符合我国国情的胃癌治疗模式，其中术前化疗疗效与接受该综合治疗模式胃癌患者预后显著相关。但是胃癌整体化疗效果不佳，因此早期筛选原发耐药患者是亟待解决的临床问题。本研究前期通过对103例胃癌患者外周血白细胞DNA中33个与5-Fu及铂类药物疗效相关的SNP位点行Snapshot检测和直接测序分析，发现ABCC2基因 rs717620位点GG基因型与化疗敏感性减低以及预后差相关；本研究拟对该相关性进行分子生物学水平的验证，首先通过进一步扩大临床样本量验证相关性，进而通过构建ABCC2过表达、敲除细胞系并构建小鼠成瘤模型以及ABCC2基因敲除小鼠模型在细胞水平、动物模型水平进一步验证ABCC2表达水平改变导致化疗疗改变的分子生物学机制。该多态性与化疗疗效以及预后的相关性有助于我们在临床上提前甄别出潜在可能出现化疗耐药的患者，避免不必要的治疗，并给予及时

围手术期化疗联合D2根治手术的综合治疗模式是最符合我国国情的胃癌治疗模式，其中术.前化疗疗效与接受该综合治疗模式胃癌患者预后显著相关。但是胃癌整体化疗效果不佳，因此早期筛选原发耐药患者是亟待解决的临床问题。本研究前期通过对103例胃癌患者外周血白细胞DNA中33个与5-Fu及铂类药物疗效相关的SNP位点行Snapshot检测和直接测序分析，发现ABCC2基因 rs717620位点CC基因型与化疗敏感性减低以及预后差相关；本研究拟对该相关性进行分子生物学水平的验证。 .首先在肿瘤组织中检测验证了rs717620位点SNP与胚系的高度一致性，且与化疗疗效有类似的相关性；然后通过临床样本，多个胃癌细胞系中的检测，验证rs717620 SNP与ABCC2表达水平的相关性，并进一步通过双荧光酶报告实验，rs717620 CT/TT 突变基因型细胞系的构建进一步证明了rs717620 位点在ABCC2表达调控中的作用，明确了CT/TT基因型与ABCC2高表达的对应性；其次通过近1048例胃癌术后样本IHC检测验证了ABCC2表达与肿瘤分化类型，预后的相关性；继而通过构建ABCC2过表达、敲除细胞系以及小鼠成瘤模型探索ABCC2对化疗敏感性的影响，结果显示ABCC2作为细胞膜表面多药耐药泵分子的作用并不显著，而是通过发挥谷胱甘肽外排泵作用，诱发肿瘤细胞在氨基酸饥饿条件下发生脂质过氧化，铁死亡等系列分子生物学事件，从而抑制肿瘤细胞的增殖和迁移，进而改善预后。.综合前期结果，我们初步结论是ABCC2 rs717620 CT/TT基因型对应更高的ABCC2表达水平，更好的分化类型以及更好的化疗疗效和预后；与预后相关的机制可能与其谷胱甘肽外排泵的功能相关；其与化疗疗效相关的潜在机制还有待进一步探索。