Duplication of the upstream regulatory sequences increases the transformation potential of human papillomavirus type 11.

Infections with certain types of papillomaviruses, e.g., human papillomavirus type 16 (HPV-16), often progress to cancer. Malignant lesions associated with the closely related HPV-11 are extremely rare. Additionally, HPV-11 DNA, unlike HPV-16, does not normally transform cells in vitro. We determined that HPV-11 DNA was able to transform baby rat kidney cells in a ras-dependent focus assay when the upstream regulatory region (URR) was present in two copies. Addition of a second HPV-11 URR or an HPV-16 URR was equally effective and was position and orientation independent. The transformation was enhanced by dexamethasone. On passage the HPV-11 genome was not retained at a detectable level. This analysis supports isolated observations in vivo that duplications of regulatory sequences in HPV-11 increase the transformation potential of this virus type.