摘要：To investigate the role of tobacco smoking and asbestos fibers in the etiology of human lung cancer, we examined the activating point mutations in the K-ras oncogene in DNA samples from 49 patients. Mutations were found more often in tissue from adenocarcinomas (12/21) than in tissue from tumors other than nonadenocarcinomas of the lung (3/28). Among the adenocarcinoma patients, asbestos exposure was predictive of K-ras mutation (odds ratio, 4.9; 95% confidence interval, 0.7-34.3); in patients with other types of lung cancer, the relation appeared to be an inverse one, but the numbers were small. The proportion of heavy smokers (over 50 pack-years) was 60% among people with K-ras mutations and 35% among the K-ras-negative subjects, suggesting that smoking causes K-ras mutations. If mutations in K-ras genes are caused by smoking, asbestos would act as a promoting agent by conferring selective growth conditions for clonal expansion on these mutated cells. Asbestos may favor recruitment of (initiated) K-ras mutation-positive cells in the multistage process of carcinogenesis by stimulating cellular growth. Full text Full text is available as a scanned copy of the original print version. Get a printable copy (PDF file) of the complete article (634K), or click on a page image below to browse page by page. Links to PubMed are also available for Selected References . 189 190 191 192
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