Immunohistochemical expression of p53 in animal tumors: a methodological study using four anti-human p53 antibodies

Mutations in the p53 tumor suppressor gene are the most common genetic alte rations in human cancers. These mutations usually lead to strongly enhanced protein stabilization and allow detection by immunohistochemistry. Two mon oclonal (DO-7 and PAb-240) and two polyclonal (Ab-7 and CM-1) antibodies we re evaluated by standard immuno-peroxidase method in domestic animal tumors , chiefly squamous cell carcinomas (SCC), and osteosarcomas as positive con trols. Immunoreactivity was detected in SCC of cattle, sheep, horse and cat as well as in feline actinic keratosis, with PAb-240 and CM-1 antibodies. One polyclonal antibody (Ab-7) did not give positive result at all, whereas DO-7 monoclonal antibody did not react in dogs and cats. Immunodetection o f p53 protein is thus possible in all domestic species tested, especially w ith CM-1 and PAb-240 antibodies, and p53 alterations seem to occur early in carcinogenesis of feline SCC as in comparable human lesions.