Analysis of HPV-Positive and -Negative Vulvar Carcinomas for Alterations in c-myc, Ha-, Ki-, and N-ras Genes

Mutation or overexpression of certain host genes, including c-myc, Ha-ras, and Ki-ras, have been associated with genital squamous neoplasia, specifically in the cervix, and have been implicated in the natural history of these tumors. The relationship of these host gene alterations to vulvar squamous cell carcinomas has not been previously studied. We analyzed archival material from 13 human papillomavirus-positive and-negative vulvar squamous cell carcinomas for mutations in Ha-, Ki-, and N-ras genes, and a smaller number of flesh samples for c-myc amplification, using PCR-based assays. For comparison, eight cervical squamous cell carcinomas (three fixed and five fresh) were also analyzed. Analysis for ras mutations revealed a previously reported silent allelic variant at nucleotide 1744 in the Ha-ras gene, but no mutations in codons 12, 13, or 61. Similarly, genomic amplification of c-myc beyond a maximum of three haploid copies was not identified in the cases. These findings indicate that alterations in myc or ras sequences are not linked to vulvar squamous cell carcinomas or to the presence or absence of HPV nucleic acids. Moreover, they apparently will not distinguish vulvar from cervical carcinomas, both groups appearing to be unlikely to harbor these sequence alterations.