Melanoma cells can tolerate high levels of transcriptionally active endogenous p53 but are sensitive to retrovirus-transduced p53.
Malignant melanomas are frequently characterized by elevated levels of wild-type p53, suggesting that p53 function could be suppressed by a mechanism different from p53 mutation. We analysed the functionality of the p53-signaling pathway in a panel of seven human melanoma cell lines consisting of one p53-deficient line, two lines with mutant p53, and four lines expressing wild-type p53. Only lines with wild-type p53 were characterized by elevated levels of endogenous p21, high activity of p53-responsive reporters and accumulation of p53 in response to genotoxic stress, common properties of functional p53. The presence of wild-type p53 was associated with depletion or loss of p14ARF and p16 expression. The levels of p33ING1b and p24ING1c, two major products of Ing1 locus and putative coregulators of p53, were elevated in all cell lines tested; however, ectopic expression of either ING1 isoform had no effect on cell proliferation. All lines retained expression of Apaf-1, and all but one remained sensitive to ectopic expression of retrovirus-transduced p53. Our data indicate that regardless of abnormally high levels of p53 in melanomas, their p53 remains competent in transactivation of its targets, and, if highly overexpressed, capable of growth inhibition. Hence, the p53 pathway in malignant melanomas can be considered for pharmacological targeting and anticancer gene therapy.
Kichina
Julia V
JV
Department of Molecular Biology, Lerner Research Institute, Cleveland Clinic Foundation, 9500 Euclid Avenue, Cleveland, OH 44195, USA.
Rauth
Sikha
S
Das Gupta
Tapas K
TK
Gudkov
Andrei V
AV
D053477:Apoptotic Protease-Activating Factor 1; D018797:Cell Cycle Proteins; D015500:Chloramphenicol O-Acetyltransferase / Q000096:biosynthesis / Q000235:genetics; D050759:Cyclin-Dependent Kinase Inhibitor p21; D016213:Cyclins / Q000378:metabolism; D004268:DNA-Binding Proteins; D005720:Gamma Rays; D015972:Gene Expression Regulation, Neoplastic / Q000528:radiation effects; D017930:Genes, Reporter; D016147:Genes, Tumor Suppressor; D016158:Genes, p53; D005822:Genetic Vectors / Q000235:genetics; D006801:Humans; D000076023:Inhibitor of Growth Protein 1; D047908:Intracellular Signaling Peptides and Proteins; D008545:Melanoma / Q000378:metabolism* / Q000473:pathology; D009363:Neoplasm Proteins / Q000172:deficiency / Q000378:metabolism*; D009687:Nuclear Proteins; D011506:Proteins / Q000378:metabolism; D011993:Recombinant Fusion Proteins / Q000096:biosynthesis / Q000378:metabolism; D012190:Retroviridae / Q000235:genetics; D015398:Signal Transduction; D015533:Transcriptional Activation; D014161:Transduction, Genetic; D014407:Tumor Cells, Cultured / Q000378:metabolism / Q000528:radiation effects; D025803:Tumor Suppressor Protein p14ARF / Q000378:metabolism; D016159:Tumor Suppressor Protein p53 / Q000172:deficiency / Q000378:metabolism*; D025521:Tumor Suppressor Proteins
C506592:APAF1 protein, human; D053477:Apoptotic Protease-Activating Factor 1; C493956:CDKN1A protein, human; D018797:Cell Cycle Proteins; D050759:Cyclin-Dependent Kinase Inhibitor p21; D016213:Cyclins; D004268:DNA-Binding Proteins; C501503:ING1 protein, human; D000076023:Inhibitor of Growth Protein 1; D047908:Intracellular Signaling Peptides and Proteins; D009363:Neoplasm Proteins; D009687:Nuclear Proteins; D011506:Proteins; D011993:Recombinant Fusion Proteins; D025803:Tumor Suppressor Protein p14ARF; D016159:Tumor Suppressor Protein p53; D025521:Tumor Suppressor Proteins; D015500:Chloramphenicol O-Acetyltransferase