Mutant p53 melanoma cell lines respond differently to CP-31398-induced apoptosis.
BACKGROUND
p53, a commonly mutated gene in human cancers, participates in cell cycle arrest, DNA repair and apoptosis. A small pharmacological compound, CP-31398, was found to have the ability to promote proper p53 protein folding, activate p53 transcription of downstream targets, and slow tumour growth in mice. Additionally, CP-31398 was found to be able to convert mutant p53 to wild-type conformation in several cell lines.


OBJECTIVE
To examine if CP-31398 can revert all mutant p53 proteins to wild-type function.


METHODS
We studied a series of apoptotic responses to CP-31398 in three melanoma cell lines varying in p53 mutation status.


RESULTS
Upon a moderate dose of CP-31398 treatment (15 microg mL(-1)), only the wild-type p53 MMRU and the single p53 point mutation MeWo cells exhibited apoptosis. Another melanoma cell line, Sk-mel-110, containing multiple p53 mutations, did not exhibit apoptosis. Although CP-31398 enhanced overall p53 protein level, its ability to promote proper folding of p53 protein was limited to CP-31398-sensitive MMRU and MeWo cells. These sensitive cells showed an increased Bax and PUMA transcription, altered mitochondrial membrane potential, followed by the release of cytochrome c, and cleaved caspase-9 and caspase-3. We also demonstrated that Apaf-1 was not involved in CP-31398-mediated apoptosis.


CONCLUSIONS
Our results suggest that the ability of CP-31398 to revert mutant p53 proteins to wild-type conformation may be correlated to p53 mutational status. More studies are necessary, to further investigate the effect of CP-31398 on mutant p53 and its potential applications as an anticancer agent.
Ho
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Department of Medicine, Division of Dermatology, Vancouver Coastal Health Research Institute, University of British Columbia, Vancouver, BC, Canada.
Li
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D017209:Apoptosis / Q000187:drug effects*; D053477:Apoptotic Protease-Activating Factor 1; D053148:Caspase 3; D053453:Caspase 9; D020169:Caspases / Q000378:metabolism; D002470:Cell Survival / Q000187:drug effects; D045304:Cytochromes c / Q000378:metabolism; D004305:Dose-Response Relationship, Drug; D016158:Genes, p53; D006801:Humans; D047908:Intracellular Signaling Peptides and Proteins / Q000378:metabolism; D008545:Melanoma / Q000235:genetics* / Q000378:metabolism / Q000473:pathology; D008564:Membrane Potentials / Q000187:drug effects; D008928:Mitochondria / Q000378:metabolism; D011506:Proteins / Q000378:metabolism; D011743:Pyrimidines / Q000494:pharmacology*; D020133:Reverse Transcriptase Polymerase Chain Reaction / Q000379:methods; D014407:Tumor Cells, Cultured; D016159:Tumor Suppressor Protein p53 / Q000378:metabolism
C506592:APAF1 protein, human; D053477:Apoptotic Protease-Activating Factor 1; D047908:Intracellular Signaling Peptides and Proteins; D011506:Proteins; D011743:Pyrimidines; D016159:Tumor Suppressor Protein p53; D045304:Cytochromes c; C505407:CASP3 protein, human; C506433:CASP9 protein, human; D053148:Caspase 3; D053453:Caspase 9; D020169:Caspases; C402665:CP 31398