肺癌线粒体DNA突变的研究

背景与目的：近年来已经在多种肿瘤中发现了线粒体DNA（mitochondrial DNA,mtDNA)突变,但其意义尚不明确。本研究通过检测肺癌组织中的mtDNA突变,探讨mtDNA突变在人肺癌发生中的作用。方法：提取58例肺癌组织及其相应病灶的远端非癌肺组织和外周血淋巴细胞的总DNA（包括核DNA和mtDNA),用巢式PCR（nested PCR)方法扩增相互重叠且涵盖mtDNA全长的58个DNA片段。经PCR产物直接测序法测定mtDNA序列,通过与外周血淋巴细胞比较,确定肺癌组织mtDNA突变。结果：在36例（62．1％）肺癌组织中发现66个突变,其中点突变58个,插入突变4个,缺失突变4个。这些突变分散地分布于mtDNA,以D－loop区突变最多,为18个,在多肽编码区没有明显的热点突变区。在多肽编码区检出的43个点突变中,20个突变不改变氨基酸编码序列。在8例病灶远端非癌肺组织中发现了与相应肿瘤相同的突变。结论：肺癌组织中mtDNA突变可能是随机发生的,且大部分突变对肿瘤的发生可能没有影响,但其有望成为一种肿瘤诊断的分子标记。

Mitochondrial DNA mutations in lung cancer

Background and Objective:Mitochondiral DNA(mtDNA)mutations has been identified in various cancers,but their significance was unknown.This study aimed to detect m tDNA mutations in lung cancer,and to investigate their roles in the carcinogenesis of human lung.Methods:Total DNA(including nuclear DNA and mtDNA)was extracted from the tumor tissues,correspondi ng distal non-cancerous lung tissues,and peripheral lymphocytes deriv ed from 58patients with lung cancer.Fifty-eight overlapping fragments and covering compl ete sequence of mtDNA were amplified by nested PCR,and the PCR products were sequen ced directly with the cycle sequencing methods.The mtDNA mutations in th e tumor tissue were determined by comp aring with corresponding and peripheral lymphocytes.Results:Sixty-six mutations were identified in 36cases(62.1%)of lung cancer,including 58point mu tations,4insertions,and 4deletio ns.These mutations were dispersedly distrib uted in the full length of mtDNA.The f requency of mutation in D-loop is the highest,in which 18mutations were detected.No mutation hot spot was found in peptid e-coding regions.Among 43point mut ations identified in protein-coding regio n,20were silent mutations.In8patients,identical mutations were detected both in the tumor tissues and corresponding distal non-cancerous tissues.Conclusion:Most of mtDNA mutations in the lung cancers investigated were occurred randoml y and might have no impact on carcinogenesis;whereas the homopl asmic mutations may provide a potential diagnostic marker for lu ng cancer.