Transactivation-deficient DeltaTA-p73 acts as an oncogene.

The recently discovered p53-family member p73 displays significant homology to p53, but data from primary tumors and knockout mice argue against p73 being a classical tumor suppressor. We report on the overexpression of NH(2)-terminally truncated, transactivation-deficient p73 proteins (DeltaTA-p73) in human cancer cells. Moreover, we show that DeltaTA-p73 overexpression results in malignant transformation of NIH3T3 fibroblasts and tumor growth in nude mice, thereby providing the experimental evidence for an oncogenic function of DeltaTA-p73. Apparently, increased expression of NH(2)-terminally truncated p73 isoforms conveys the TP73 gene with oncogenic activity that appears to be actively selected for during tumor development.