COEXISTENCE OF EPISOMAL AND INTEGRATED HPV16 DNA IN SQUAMOUS-CELL CARCINOMA OF THE CERVIX

Aims-To investigate the integration of human papillomavirus (HPV)16 in 13 HPV16 positive cervical squamous carcinomas. Methods-Samples were investigated by Southern blot analysis of the Pst I digestion pattern, two-dimensional gelelectrophoresis, and in situ hybridisation. Result s-Integration of HPV16 was found in all cases. In 12 biopsy specimens episomal HPV16 DNA and integrated HPV16 DNA were seen. The episomal DN A occurred as dimers and multimers. In situ hybridisation showed that both integrated and episomal HPV16 DNA were present in the same cell i n most tumour cell nuclei.Conclusions-An intact episomal E2 gene is pr esent in most cases of these cervical cancers, and could therefore rep lace the regulatory function of an integrated defective E2 gene.