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 gel-electrophoresis, and in situ hybridisation.

RESULTS

Integration of HPV16 was found in all cases. In 12 biopsy specimens episomal HPV16 DNA and integrated HPV16 DNA were seen. The episomal DNA occurred as dimers and multimers. In situ hybridisation showed that both integrated and episomal HPV16 DNA were present in the same cell in most tumour cell nuclei.

CONCLUSIONS

An intact episomal E2 gene is present in most cases of these cervical cancers, and could therefore replace the regulatory function of an integrated defective E2 gene.