K-ras Gene Mutation in Non-Small Cell Lung Cancer

ABSTRACT

PURPOSE: Point mutation of the K-ras gene causes irreversible binding of GTP to the P21-ras protein, which induces nuclear transcription factors and enhances cellular proliferation. Point mutation of the K-ras gene is known to be a poor prognostic marker of an adenocarcinoma of the lung. As about 30% of adenocarcinomas harbor the K-ras mutation, studies are being undertaken trying to use the K-ras mutation as a marker for the early detection of lung cancer. In Korea, squamous cell carcinomas are more prevalent than adenocarcinomas, but the incidence of the K-ras mutation has not been properly investigated. MATERIALS AND METHODS: Using 25 surgically resected lung cancer specimens (10 squamous cell lung carcinomas, 10 adenocarcinomas and 5 non-small cell lung cancers), 25 pairs of DNA were extracted from cancerous and normal lung tissues. After PCR, with two sets of primers flanking codons 12~13 and 61 of the K-ras gene, the mutation was screened using single strand conformational polymorphism (SSCP). To verify the SSCP findings, automatic sequencing was also performed for all DNA's from the tumor and normal lung tissues. RESULTS: No samples with a band shift in SSCP were observed. In the sequencing of the 25 pairs of DNA, there were no mutations in codons 12, 13 or 61 of the K-ras gene. CONCLUSION: As there were no mutations in the K-ras codons 12, 13 and 61 in this study, the incidence of the K-ras mutation, in Korean lung cancer, may well be very low. However, further investigations on a larger population will be required, as we only studied 25 non-small cell lung cancer specimens, with only 10 adenocarcinomas.