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应用分子生物学方法确定同期性多灶性肺癌的克隆来源 ,为肺癌的分期提供依据.方法 :对 2例肺部同期多灶性肺癌患者的每个病灶都用石蜡切片做显微解剖及蛋白酶K消化 ,提取基因组DNA ,先后两次PCR扩增K -ras第 1外显子和 p5 3外显子 5~ 9,用微型凝胶做非同位素性SSCP电泳 ,银染色后观察.对有变异电泳图型的样本用DNA序列测定去证实点突变.结果 :例 1的两个肺癌结节 ,仅 1个表现K -ras第 1外显子 12密码子突变 (GGT→TGT) ;例 2的 3个肺癌结节 ,1个表现K -ras第 1外显子 12密码子突变 (GGT→TGT) ,另 1个表现 p5 3第 5外显子 48密码子突变 (GTG→TTG) ,第 3个无突变发现.结论 :此 2例的多灶性肺癌均为不同的克隆来源.因此 ,提出应用非同位素PCR -SSCP分析 ,检测K -ras和p5 3点突变是鉴别多发性肺癌克隆起源的有效方法.“,”Objective:When a patient presents with multiple pulmonary lesions with a similar malignant histology, it is a dilemma to decide the clonal origin of individual lesions and the tumor staging. However, disease stage is the most important factor for determining prognosis and treatment planning for lung cancer. We are able to identify the clonality using molecular biology technique in this report.Methods:Each lesion in 2 cases with multiple lung cancers was microdissected from paraffin slides and digested with proteinase K. Genomic DNA extracted was amplified by 2 sequential polymerase chain reactions (PCRs) with primers for exon 1 of K-ras, and for each exon of exon 5 to 9 of p53, and then followed by electrophoresed in a minigel for non-radioisotopic single-strand conformation polymorphism (SSCP) and visualized by silver staining. DNA sequencing was performed if necessary to confirm a mutation found upon SSCP analysis.Results:There were two malignant nodules in case 1, only one presented a mutation of K-ras in codon 12 of exon 1 (GGT→TGT); there were three malignant modules in case 2, one presented a mutation of K-ras in codon 12 of exon 1 (GGT→TGT),an other presented a mutation of p53 in codon 48 of exon 5 (GTG→TTG), none of mutation was in third one.Conclusion:The multiple lung cancers in both the cases were of different clonal origins. Therefore, it is recommended that the detection of the point mutations of K-ras and p53 by PCR-SSCP is an effective method to differentiate the clonal origins of multiple malignant nodules of the lung.