Differences in K-ras codon 12 mutation frequency between "high-risk" and "low-risk" HPV-infected samples

Objectives, The current study was designed to determine the association between K-ras point mutations and the presence of high- and low-risk NPV types in noncancerous samples. Methods. One hundred fifty-five noncancerous cytological samples from genital specimens positive for HPV-6, -16, or -18 were analyzed for codon 12 ras point mutations. DNA samples were subjected to nested PCR for the detection of HPV genome. Mutations at the first and second bases of K-ras codon 12 were detected using specific enriched PCR. Results. Eleven percent of the HPV-positive samples analyzed showed mutation in K-ras codon 12 (17 of 155). Mutations were detected in 8 of 53 HPV-16- (15%) and 8 of 38 HPV-18-positive samples (21%). Nevertheless, when HPV-6-positive samples were screened for K-ras mutations only 1 of 64 samples was found mutated (1.56%). Statistical analysis using the chi(2) test showed a highly significant difference (chi(2) = 9.865, P < 0.01) when the rate of mutation for samples positive for high-risk HPV types (16 and 18) was compared with the frequency found in low-risk-infected samples (HPV-6). Conclusion. These results could be considered an indicator of the association between K-ras codon 12 mutations and the presence of high-risk NPV types. (C) 1999 Academic Press.