Intercellular induction of apoptosis in transformed cells does not depend on p53.

Transformed fibroblast from p53 null/null mice were tested for their sensitivity to intercellular induction of apoptosis by TGF-beta-treated nontransformed cells. They were found to be as sensitive as p53-positive transformed cells. Based on morphological criteria, detection of chromatin condensation and DNA strand breaks, death of p53-negative transformed cells was due to apoptosis. p53-negative nontransformed cells were as efficient in the induction of apoptosis in transformed cells as p53-positive nontransformed cells. These data show that intercellular induction of apoptosis in transformed cells does not depend on functional p53. Therefore it may be assumed that mutations of p53 or modulation of its concentration are without relevance for this particular aspect of control of oncogenesis.