Sagawa M, Saito Y, Fujimura S, Linnoila R I
Biomarkers and Prevention Research Branch, National Cancer Institute, Rockville, Maryland 20850, USA.
Br J Cancer. 1998 Mar;77(5):720-3. doi: 10.1038/bjc.1998.118.
In order to determine the topographical distribution of the K-ras codon 12 mutations in carcinoma and preneoplastic lesions of the lung, selective ultraviolet radiation fractionation, as well as microdissection followed by polymerase chain reaction-restriction fragment length polymorphism (PCR-RELP), was performed. Fourteen of 61 samples amplified (23.0%) had a mutation in the K-ras codon 12. Of 41 adenocarcinoma, 12 samples (29.3%) had a mutation, whereas none of the squamous cell carcinomas had a mutation. One of six large-cell carcinomas, one of three carcinoid tumours and none of three other carcinomas had a mutation. Direct sequencing revealed that K-ras codon 12 of six samples were TGT (Cys), five samples were GTT (Val), two samples were GCT (Ala) and one sample was TTT (Phe). A total of 113 lesions of 13 cases covered by dot were amplified after UV radiation. All of 74 carcinoma lesions had the mutation, and intratumour heterogeneity was not observed. Of 39 non-malignant lesions, one type II cell hyperplasia had the mutation, which suggests that the K-ras mutation occurs in the early stage of carcinogenesis. The lack of intratumour heterogeneity supports the hypothesis.
为了确定K-ras密码子12突变在肺癌癌组织及癌前病变中的拓扑分布，我们采用了选择性紫外线辐射分级分离法，以及显微切割后进行聚合酶链反应-限制性片段长度多态性分析（PCR-RELP）。61个样本中有14个（23.0%）扩增产物存在K-ras密码子12突变。41例腺癌中，12个样本（29.3%）有突变，而鳞状细胞癌样本均无突变。6例大细胞癌中有1例、3例类癌肿瘤中有1例有突变，其他3例癌均无突变。直接测序显示，6个样本的K-ras密码子12为TGT（Cys），5个样本为GTT（Val），2个样本为GCT（Ala），1个样本为TTT（Phe）。紫外线辐射后，对13例病例中113个点状覆盖的病变进行了扩增。74个癌性病变均有突变且未观察到肿瘤内异质性。39个非恶性病变中，1例II型细胞增生有突变，这表明K-ras突变发生在致癌作用的早期阶段。肿瘤内缺乏异质性支持这一假说。
