基于Cf DNA检测探索局部晚期食管鳞癌同期放化疗敏感性相关基因的初步研究

Preliminary study of the detection of genes related to sensitivity to concurrent chemoradiotherapy based on circulating free DNA in locally advanced esophageal squamous cell carcinoma

目的探索局部晚期食管鳞癌同期放化疗敏感性相关基因及分子标志物。方法收集2017—2018年间31例在中国医学科学院肿瘤医院采用根治性同期放化疗的局部晚期食管鳞癌患者治疗前外周血并提取血浆Cf DNA,采用基于NovaSeq6000高通量测序平台的目标基因捕获测序技术检测靶基因与肿瘤突变负荷(TMB)变化。根据放化疗近期疗效将患者分为放化疗敏感组(CR+PR)和放化疗抗拒组(SD+PD),综合生物信息学和临床资料分析两组间的基因突变和TMB差异。结果31例患者测序数据中突变频率>10%的肿瘤相关基因为Tp53、NOTCH1、BRAF、FGFR4、CDKN2A、ATRX和AXIN2,他们在放化疗敏感组和放化疗抗拒组均有分布且相近。高频突变基因主要与7条信号通路相关,主要涉及凋亡信号通路和细胞周期信号通路等,它们主要参与的是RTK-RAS信号通路。放化疗敏感组患者TMB值高于放化疗抵抗组(P=0.04),但GXYLT1和KRT18基因在放化疗抵抗组患者的突变率高于放化疗敏感组(P<0.05)。结论Tp53、NOTCH1和CDKN2A可能是与食管鳞癌发生发展相关的高频突变基因,而KRT18、GXYLT1和TMB与局部晚期食管鳞癌患者同期放化疗敏感性密切相关。

Objective To explore the genes and molecular markers related to the sensitivity to concurrent chemoradiotherapy in patients with locally advanced esophageal squamous cell carcinoma.Methods The peripheral blood sample of 31 patients with locally advanced esophageal squamous cell carcinoma receiving radical concurrent chemoradiotherapy was collected and the plasma circulating free DNA(cf-DNA)was extracted before treatment.The target gene capture sequencing technology based on NovaseQ6000 high-throughput sequencing platform was employed to detect the changes of target genes and tumor mutation burden(TMB).According to the short-term efficacy of chemoradiotherapy,all patients were divided into the chemoradiotherapy-sensitive group(CR+PR)and chemoradiotherapy-resistant group(SD+PD).Bioinformatics and clinical data were adopted to analyze the differences of gene mutation and TMB between two groups.Results In the sequencing data of 31 patients,the tumor-related genes with a mutation frequency above 10%were Tp53,Notch1,BRAF,FGFR4,CDKN2A,ATRX and Axin2,which were almost equally distributed between the CR+PR and SD+PD groups.High-frequency mutant genes were associated with 7 signaling pathways,mainly involved in the RTK/RAS signaling pathways.The TMB value in the CR+PR group was higher than that in the SD+PD group(P=0.04),however,the mutation rate of GXYLT1 and KRT18 genes in the SD+PD group was higher than that in the CR+PR group(P<0.05).Conclusions Tp53,Notch1 and CDKN2A may be the high-frequency mutant genes associated with the incidence and progression of esophageal squamous cell carcinoma.KRT18,GXYLT1 and TMB are closely correlated with the sensitivity to concurrent chemoradiotherapy of patients with locally advanced esophageal squamous cell carcinoma.