非小细胞肺癌循环肿瘤DNA突变特征与放疗敏感相关性研究

Correlation between Circulating Tumor DNA Mutation and Radiation Sensitivity in Non-Small Cell Lung Cancer

目的:通过高通量测序技术检测非小细胞肺癌患者外周血循环肿瘤DNA(circulating tumor DNA,ctDNA)的突变特征,并分析其与肿瘤等效退缩率之间的相关性,探讨ctDNA对放射治疗敏感性的评估价值。方法:纳入四川省肿瘤医院初治的非小细胞肺癌患者35例,采集静脉血分离血浆ctDNA,进行Illumina HiSeq PE150测序,获取突变特征谱;按肿瘤等效退缩率将入组患者分为敏感组和抵抗组。采用t检验或秩和检验进行统计学分析。结果:非小细胞肺癌ctDNA突变特征主要表现为单核苷酸突变,其中以外显子编码区域错义突变为主,另有部分同义突变,非编码RNA突变及非翻译区突变等,但它们的发生率在敏感组和抵抗组之间差异均无统计学意义(P>0.05);基因拷贝数变异是非小细胞肺癌ctDNA突变的另一主要表现,它包括有变异类型的重复和缺失,变异数目的多少及区域的大小,其中变异类型及数目在敏感组和抵抗组之间差异无统计学意义(P>0.05),但基因拷贝数变异区域的大小,在敏感组和抵抗组之间差异具有统计学意义(P=0.014),秩相关分析显示相关系数r_s=0.554,进一步分析其变异重复类型区域的大小,在敏感组和抵抗组之间差异也具有统计学意义(P=0.008),秩相关系数r_s=0.591。结论:非小细胞肺癌ctDNA突变中非同义突变、非翻译区突变、非编码RNA突变均与放射敏感无相关性,基因拷贝数变异类型及数目均与放射敏感性无关,但变异区域的大小,尤其是重复区域的大小与肿瘤放射敏感呈现出负相关性。

Objective:To detect the mutational characteristics of circulating tumor DNA(ctDNA)in peripheral blood in patients with non-small cell lung cancer(NSCLC)by using high-throughput sequencing technology,and analyze the correlation between it and the therapeutic effect of radiotherapy,so as to evaluate the sensitivity of ctDNA to radiotherapy.Methods:Thirty-five NSCLC patients in Sichuan Cancer Hospital were included.Plasma ctDNA was extracted and sequenced by IlluminaHiSeqPE150.The enrolled patients were assigned to the sensitive group and the resistant group according to the equivalent regression rate of the tumor.t-test or rank sum test were used for statistical analysis.Results:Mutations in ctDNA from NSCLC patient plasma were characterized by single nucleotide mutations;and missense mutations in exons were predominant;besides,some synonymous mutations,mutations in non-coding RNA and mutations in untranslated regions;but differences were not statistically significant between the sensitive group and the resistant group(P>0.05).Gene copy number variation(CNV)was another major manifestation of ctDNA mutation in NSCLC.It included two types,duplication and deletion,focusing on the number of variation and the size of regions.There were no significant differences between the sensitive group and the resistant group in type and number of variation(P>0.05).However,the CNV total region size was significantly different between the two groups(P=0.014),and the Spearman rank correlation analysis showed that the correlation coefficient was 0.554.Further analysis demonstrated that the CNV duplication region size was also significantly different between the two groups(P=0.008),and the rank correlation coefficient was 0.591.Conclusion:Neither non-synonymous mutation,untranslated region mutation and non-coding RNA mutation among mutations in ctDNA from NSCLC patient plasma nor the type or number of gene copy number variation are correlated to radiosensitivity,but the CNV total region size,especially the CNV duplication region size,is negatively correlated to radiosensitivity.