The physical state of human papillomavirus type 16 DNA in cervical carcinomas of Hong Kong Chinese.

The presence of human papillomavirus (HPV) in 15 cervical carcinoma specimens obtained from Hong Kong Chinese patients was analyzed by Southern blot hybridization studies. In nine (60%) of them, HPV 16 genomes were detected, while two others (13.3%) were found to harbor HPV DNA of unknown type closely related to HPV 16. All of them were classified as squamous cell carcinomas according to WHO guidelines. In addition, the presence of HPV 18 was shown in another two (13.3%) squamous cell carcinoma samples. Among the nine tumors harboring HPV 16, four specimens (44.4%) have HPV in integrated forms, while four others (44.4%) have HPV in episomal forms. The simultaneous presence of both episomal and integrated forms was demonstrated in the remaining tissue sample (11.2%). The result obtained here indicates a strong association between HPV infection and cervical carcinogenesis in Hong Kong Chinese, with HPV 16 prevalent in squamous cell carcinoma. Moreover, the persistence of HPV 16 episomes in some of the tumor specimens suggests that extrachromosomal HPV DNA, possibly acting synergistically with other oncogenic factors, is also capable of inducing cervical cancer.