Rhesus papillomavirus type 1 cooperates with activated ras in transforming primary epithelial rat cells independent of dexamethasone.

Rhesus Papillomavirus type 1 (RhPV-1) was recently cloned from a rhesus monkey lymph node metastasis of a penile squamous cell carcinoma. In this paper, we demonstrate that RhPV-1 cooperates with the activated ras oncogene to transform primary cells at a level comparable to human papillomavirus type 16. The viral DNAs were cloned such that their expression was under the control of their natural promoter elements. Unlike human papillomavirus type 16, RhPV-1 DNA cooperated with ras independently of the hormone dexamethasone. However, dexamethasone did have a positive influence on the ability of some RhPV-1 cotransformed cells to grow in soft-agar assays. The transformed cells are highly tumorigenic in vivo in nude mice.