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Selective induction of apoptosis through the FADD/caspase‐8 pathway by a p53 c‐terminal peptide in human pre‐malignant and malignant cells

A p53 C‐terminal peptide (aa 361–382, p53p), fused at its C‐terminus to the minimal carrier peptide of antennapedia (17 aa, Ant; p53p‐Ant), induced rapid apoptosis in human cancer cells, via activation of the Fas pathway. We examined p53p‐Ant mechanism of action, toxicity in various human normal, non‐malignant, pre‐malignant and malignant cancer cells and investigated its biophysical characteristics. p53p‐Ant selectively induced cell death in only pre‐malignant or malignant cells in a p53‐dependent manner and was not toxic to normal and non‐malignant cells. p53p‐Ant was more toxic to the mutant p53 than wild‐type p53 phenotype in H1299 lung cancer cells stably expressing human temperature‐sensitive p53 mutant 143Ala. Surface plasmon resonance (BIACORE) analysis demonstrated that this peptide had higher binding affinity to mutant p53 as compared to wild‐type p53. p53p‐Ant induced‐cell death had the classical morphological characteristics of apoptosis and had no features of necrosis. The mechanism of cell death by p53p‐Ant was through the FADD/caspase‐8‐dependent pathway without the involvement of the TRAIL pathway, Bcl‐2 family and cell cycle changes. Blocking Fas with antibody did not alter the peptide's effect, suggesting that Fas itself did not interact with the peptide. Transfection with a dominant‐negative FADD with a deleted N‐terminus inhibited p53p‐Ant‐induced apoptosis. Its mechanism of action is related to the FADD‐induced pathway without restoration of other p53 functions. p53p‐Ant is a novel anticancer agent with unique selectivity for human cancer cells and could be useful as a prototype for the development of new anti‐cancer agents. © 2004 Wiley‐Liss, Inc.