DETECTION OF CANINE ORAL PAPILLOMAVIRUS-DNA IN CANINE ORAL SQUAMOUS-CELL CARCINOMAS AND P53 OVEREXPRESSING SKIN PAPILLOMAS OF THE DOG USINGTHE POLYMERASE-CHAIN-REACTION AND NONRADIOACTIVE IN-SITU HYBRIDIZATION

Nineteen cutaneous and mucocutaneous papillomas, as well as 29 oral an d 25 non-oral squamous cell carcinomas of dogs were analyzed immunohis tologically for the presence of papillomavirus (PV)-antigens. Canine o ral papillomavirus (COPV)-DNA was detected in formalin-fixed, paraffin -embedded tissues by polymerase chain reaction (PCR) and non-radioacti ve in situ hybridization (ISH). Furthermore, the expression of the tum or suppressor protein p53 was investigated. PV-antigens were detectabl e in more than 50% of the oral and cutaneous papillomas, while no PV-a ntigens could be demonstrated in venereal papillomas. One squamous cel l carcinoma was PV-antigen positive, Only two cutaneous papillomas of the head showed a strong p53-specific immunostaining, while overexpres sed p53 was detectable in approximately 35% of all squamous cell carci nomas. It was possible to amplify fragments of the E6, E7 and L1 gene by polymerase chain reaction (PCR) from five of eight oral and from fi ve of eight cutaneous papillomas as well as from three oral squamous c ell carcinomas. Nine of 10 papillomas showed a strong nucleus-associat ed hybridization signal typical for COPV-DNA. In three squamous cell c arcinomas COPV-DNA was located in nests of the epithelial tumor cells surrounding 'horn pearls' or disseminated in the carcinoma tissue. The se observations support the view that COPV may also induce non-oral pa pillomas in the dog and confirm the opinion that a progression of vira l papillomas into carcinomas in dogs may occur. (C) 1998 Elsevier Scie nce B.V.