原发性非小细胞肺癌中K－ras基因突变的研究

目的探讨非小细胞肺癌（Non－smallcelllungcancer,NSCLC）组织中K－ras第12密码子点突变与NSCLC发生和发展的相关性。方法采用针对K－ras基因第12密码子特异点突变方式的引物进行PCR及银染法，分析175例新鲜NSCLC手术切除标本、43例癌旁组织及5例良性肺部疾患组织中K－ras基因第12密码子中CGT、GTT和GAT三种不同点突变方式。结果175例NSCLC组织中出现K－ras12密码子GGT→CGT突变率为34．86％（61／175），GGT→GTT突变率40．57％（71／175）及GGT→GAT突变率37．71％（66／175），总突变率为62．3％（109／175）。其中，同时出现CGT／GTT二个点突变为10．1％(11／109),CGT／GAT9．2％(10／109),GTT／GAT12．8％(14／109)，而CGT／GTT／GAT均出现突变占23．9％(26／109)。其中Ⅰ期、Ⅱ期、Ⅲ期突变率分别为64．3％、56．8％及64．0％，另外腺癌突变率为63．8％、鳞癌为60．5％及腺鳞癌为64．5％,因此K－ras点突变与肺癌的分期及病理类型均无相关性（P＞0．05）。然而，37例腺癌突变组中出现GTT／GAT突变率为17．2％(10／58)明显高于鳞癌的3．5％(3／86),二者具有明显差异（P＜0．01）。43例癌旁组织与5例良性肺部疾患组织均未发现K－ras点突变。结论K－ras12密码子点突变及多点突变普遍存在于NSCLC中，其中肺腺癌出现GTT／GAT二个点突变明显高于鳞癌，结果提示K－ras基因点突变是肺癌发生和发展的一个重要因素。

Detection of K

Objective： To study the relationship between codon 12 K－rasmutation and the pathogenesis of non－small cell lung cancer(NSCLC)． Methods： Using a sensitive allele－specific codon 12 K－ras polymerase chain reaction assay and silver stain to analyze three kinds of mutation at codon 12 of K－ras gene (CGT, GTT and GAT) in 175 NSCLC samples． Results： 109 of 175 cases (62．3％) with NSCLC had codon 12 K－ras mutation． Among them, CGT mutation was observed in 61 of 175 cases (34．86％), GTT mutation in 71 cases (40．57％) and GAT mutation in 66 cases (37．71％)． Both the CGT／GTT mutations happened in 11 cases, CGT／GAT in 10 cases and GTT／GAT in 14 cases respectively． 26 of 109 cases were found in all three kinds of mutation at codon 12 K－ras． There was no codon 12 K－ras mutation to be found in 43 surrounding non－cancerous lung tissues and 5 benign lung tumors． Since codon 12 K－ras mutation in patients with stage Ⅰ, Ⅱ and Ⅲ were 64．3％(36／56), 56．8％(25／44) and 64．0％(48／75) respectively, and K－ras mutation occurred in 63．8％ patients with adenocarcinoma, 60．5％ patients with squamous cell carcinoma and 64．5％ patients with adenosquamous cell carcinoma． There was no significant difference found between the frequency of K－ras mutation and the pathological types or TNM staging of NSCLC (P＞0．05)． However, the rate of both GTT and GAT mutations were higher in adenocarcinoma (27．03％ 10／37) than those in squamous cell carcinoma (5．77％ 3／52)(P＜0．01)． Conclusion： Codon 12 K－ras mutation occurres commonly in human NSCLC． Two or three different K－ras mutations can be found in some patients, while GTT／GAT mutations are more frequently found in adenocarcinoma than those in squamous cell carcinoma (P＜0．01)． It is suggested that K－ras mutation may play a very important role in pathogenesis of human lung cancer．