Objective: To investigate the associations between genetic variations in DNA mismatch repair genes and sensitivity as well as prognosis to preoperative chemoradiotherapy in patients with locally advanced rectal cancer. Methods: Fourteen haplotype-tagging single nucleotide polymorphisms (htSNPs) of MLH1, MLH3 and MSH2 genes were genotyped by Sequenom MassARRAY method in 146 patients with locally advanced rectal cancer who received preoperative chemoradiotherapy. The associations between genotypes and response to capecitabine-based neoadjuvant chemoradiotherapy (nCRT) were measured by odds ratios (ORs) and 95% confidence intervals (CIs), adjusted for sex, age, clinical stages and karnofsky performance score (KPS) by unconditional logistic regression model. The survival analyses were performed by the hazard ratios (HRs) and 95% CIs by Cox proportional regression model. Results: Among 146 cases, 64 patients were nCRT responders with a response rate of 43.8%. MLH3 rs175057 C>T and MSH2 rs13019654 G>T loci were associated with the sensitivity to preoperative chemoradiotherapy. Compared with the rs175057 CC genotype, the adjusted OR for patients with CT and TT genotypes was 0.42 (95% CI: 0.19-0.91; P=0.029). Moreover, for rs13019654, the adjusted OR for patients with the GT or TT genotypes was 0.49 (95% CI: 0.24-0.98; P=0.047) than those with GG genotype. The remaining 12 SNPs, including rs1540354, rs4026175, rs1981929, rs2042649, rs2303428, rs3771273, rs4608577, rs4952887, rs6544991, rs6544997, rs10188090 and rs10191478, were not significantly associated with therapeutic response to preoperative chemoradiotherapy. Meanwhile, MLH3 rs175057 C>T locus was also associated with longer overall survival time in locally advanced rectal cancer (HR=0.44, 95% CI: 0.20-0.96, P=0.038), whereas MSH2 rs3771273 T>A, rs10188090 A>G and rs10191478 T>G loci were associated with shorter overall survival time (HR=1.74, 95% CI: 1.06-2.84, P=0.028; HR=1.64, 95% CI: 1.01-2.66, P=0.046; HR=1.71, 95% CI: 1.01-2.91, P=0.047, respectively). The remaining 10 SNPs, including rs1540354, rs4026175, rs1981929, rs2042649, rs2303428, rs4608577, rs4952887, rs6544991, rs6544997 and rs13019654, were not significantly associated with prognosis. Conclusions: Genetic polymorphisms of MLH3 rs175057 and MSH2 rs13019654 loci can predict the nCRT response, while MLH3 rs175057 as well as MSH2 rs3771273, rs10188090 and rs10191478 may predict prognosis in patients with locally advanced rectal cancer who received preoperative chemoradiotherapy. Therefore, these SNPs could be used as potential genetic markers in the personalized therapy of rectal cancer.
目的： 探讨DNA错配修复基因MLH1、MLH3和MSH2遗传变异与局部进展期直肠癌患者术前同步放化疗敏感性及预后的关系。 方法： 采用Sequenom MassARRAY平台检测146例接受术前同步放化疗直肠癌患者MLH1、MLH3和MSH2基因14个标签SNP位点(htSNP)的基因型，并分析其与患者术前同步放化疗敏感性和总生存时间的关系。采用非条件Logistic回归模型和Cox比例风险回归模型计算影响局部进展期直肠癌患者术前同步放化疗敏感性和预后的独立影响因素。 结果： 146例患者均接受卡培他滨和奥沙利铂双药的术前同步放化疗，其中敏感组64例，抵抗组82例。关联分析结果显示，MLH3基因的rs175057 C>T和MSH2基因的rs13019654 G>T变异与术前同步放化疗敏感性明显相关。与携带rs175057 CC基因型患者比较，携带CT和TT基因型患者对同步放化疗的敏感性增加，治疗抵抗风险降低(OR＝0.42，95% CI为0.19～0.91，P＝0.029)。与携带rs13019654 GG基因型患者比较，携带GT和TT基因型患者对同步放化疗的敏感性增加，治疗抵抗风险降低(OR＝0.49，95%CI为0.24～0.98，P＝0.047)。rs1540354、rs4026175、rs1981929、rs2042649、rs2303428、rs3771273、rs4608577、rs4952887、rs6544991、rs6544997、rs10188090和rs10191478与术前同步放化疗的敏感性未见明显相关。多因素生存分析结果显示，MLH3基因的rs175057 C>T变异延长直肠癌患者的总生存时间，降低患者死亡风险(HR＝0.44，95%CI为0.20～0.96，P＝0.038)；MSH2基因的rs3771273 T>A、rs10188090 A>G、rs10191478 T>G变异缩短直肠癌患者的总生存时间，增高患者死亡风险(HR＝1.74，95%CI为1.06～2.84，P＝0.028；HR＝1.64，95%CI为1.01～2.66，P＝0.046；HR＝1.71，95%CI为1.01～2.91，P＝0.047)。rs1540354、rs4026175、rs1981929、rs2042649、rs2303428、rs4608577、rs4952887、rs6544991、rs6544997和rs13019654与患者的总生存时间未见明显相关。 结论： MLH3基因的rs175057和MSH2基因的rs13019654为影响局部进展期直肠癌患者术前同步放化疗敏感性的独立因素，MLH3基因的rs175057和MSH2基因的rs3771273、rs10188090、rs10191478可能是预测局部进展期直肠癌患者术前同步放化疗预后的遗传标志，对于直肠癌患者的个性化治疗具有潜在价值。.
Keywords: MLH3; MSH2; Neoplasms, rectal; Polymorphism, single nucleotide; Preoperative chemoradiotherapy; Prognosis; Sensitivity.