非小细胞肺癌相关抑癌基因甲基化谱的研究

Identification of a panel of candidate epigenetic biomarkers for non-small cell lung cancer

目的抑癌基因5′-CpG岛甲基化是非小细胞肺癌(non-smallcelllungcancer,NSCLC)中常见的表观遗传学改变,相关研究报道多为单基因位点且结果不一致。为了解我国NSCLC患者相关抑癌基因的甲基化状况,本文中筛选一组NSCLC候选甲基化谱,探讨其在NSCLC发生发展中的意义及用于早期诊断的价值。方法留取78例NSCLC患者术中癌组织,相应正常肺组织及110例I/II期NSCLC、50例肺部良性病变或健康志愿者血浆标本,用甲基化特异性聚合酶链反应(methylation-specificPCR,MSP)检测20个肺癌相关抑癌基因甲基化状况。结果 12个基因(APC、CDH13、KLK10、DLEC1、RASSF1A、EFEMP1、SFRP1、RARβ、p16INK4A、RUNX3、hMLH1和DAPK)在肿瘤组织中的甲基化高于相应正常组织,尤其是前9个基因(P≤0.001),8个基因(BRCA1、p14ARF、MGMT、NORE1A、FHIT、CMTM3、LSAMP和OPCML)甲基化程度较低或肿瘤特异性较低。多基因甲基化常见于肿瘤组织,CpG岛甲基子表型(CpGislandmethylatorphenotype,CIMP)阳性见于65.38%(51/78)的NSCLC癌组织而仅见于1.28%(1/78)的正常组织(P<0.001)。CIMP阳性与临床分期和淋巴结转移(P分别为0.007和0.031)相关。在早期NSCLC患者血浆样本中也检测出癌组织中初步筛选的9个抑癌基因的高甲基化。将APC、RASSF1A、CDH13、KLK10和DLEC15个基因联合检测,对肿瘤诊断的敏感性为83.64%,特异性为74.0%。结论 CIMP阳性是NSCLC肿瘤组织区别于正常组织的重要特征,且与临床分期和淋巴结转移相关。APC、RASSF1A、CDH13、KLK10和DLEC15个抑癌基因甲基化的联合检测可用于NSCLC的辅助诊断。

Objective 5′-CpG methylation of tumor suppressor genes （TSGs） is a universal epigenetic change in non-small cell lung cancer （NSCLC）.This study aimed to identify a panel of candidate epigenetic biomarkers for NSCLC in the Chinese population.Methods We obtained 78 paired specimens of NSCLC and adjacent normal lung tissues,as well as plasma samples from 110 cases of stage I/II NSCLC and 50 cancer-free controls,and determined the methylation status of 20 lung cancer-related TSGs using methylation-specific polymerase chain reaction （MSP）.Results Twelve of the genes,APC,CDH13,KLK10,DLEC1,RASSF1A,EFEMP1,SFRP1,RARβ,p16INK4A,RUNX3,hMLH1 and DAPK,exhibited a significantly higher frequency of methylation in NSCLC than in the normal tissues,especially the first 9 （P ≤ 0.001）,while the other 8 genes,BRCA1,p14ARF,MGMT,NORE1A,FHIT,CMTM3,LSAMP and OPCML,showed low sensitivity or specificity of methylation in NSCLC.Furthermore,methylation of multiple genes was frequently seen in cancerous tissues,with the CpG island methylator phenotype （CIMP） positive in 65.38% （51/78） of NSCLC but only in 1.28% （1/78） of the adjacent normal tissue samples （P〈 0.001）,and the CIMP positivity was correlated with the advanced stage （P = 0.007） and lymphatic metastasis （P = 0.031）.The 9 TSGs identified in cancerous tissues showed a significantly higher frequency of tumor-specific hypermethylation in NSCLC plasma,and a 5-gene set （APC,RASSF1A,CDH13,KLK10 and DLEC1） achieved a sensitivity of 83.64% and a specificity of 74.0% for NSCLC detection.Conclusion CIMP positivity plays an important role in NSCLC initiation and progression;the combined detection of the 5 genes APC,RASSF1A,CDH13,KLK10 and DLEC1 can be used as an auxiliary tool for the diagnosis of NSCLC.