Apoptosis protease activator protein-1 expression is dispensable for response of human melanoma cells to distinct proapoptotic agents.
Loss of expression of the apoptosis protease activator protein-1 (APAF-1) in human melanoma is thought to promote resistance to programmed cell death by preventing caspase-9 activation. However, the role of the APAF-1-dependent pathway in apoptosis activated by cellular stress and/or DNA damage has been recently questioned. We investigated APAF-1 expression in a large panel of human melanomas and assessed cellular response to several proapoptotic agents in tumors expressing or lacking APAF-1 protein. In two melanomas with wild-type p53 but with differential expression of APAF-1, treatment with camptothecin, celecoxib, or an nitric oxide synthase inhibitor (1400W) significantly modulated expression of 36 of 96 genes in an apoptosis-specific cDNA macroarray, but APAF-1 mRNA levels were not induced (in APAF-1(-) cells) nor up-regulated (in APAF-1(+) cells), a finding confirmed at the protein level. Treatment with cisplatin, camptothecin, etoposide, betulinic acid, celecoxib, 1400W, and staurosporine promoted enzymatic activity not only of caspases -2, -8, and -3 but also of caspase-9 in both APAF-1(+) and APAF-1(-) tumor cells. Moreover, drug-induced caspase-9 enzymatic activity could be not only partially but significantly reduced by caspase-2, -3, and -8 -specific inhibitors in both APAF-1(+) and APAF-1(-) tumor cells. In response to 1 to 100 micromol/L of cisplatin, camptothecin, or celecoxib, APAF-1(+) melanomas (n = 12) did not show significantly increased levels of apoptosis compared with APAF-1(-) tumors (n = 7), with the exception of enhanced apoptosis in response to a very high dose (100 micromol/L) of etoposide. These results suggest that the response of human melanoma cells to different proapoptotic agents may be independent of their APAF-1 phenotype.
Zanon
Marina
M
Human Tumor Immunobiology Unit, Department of Experimental Oncology and Department of Pathology, Istituto Nazionale per lo Studio e la Cura dei Tumori, Milan, Italy.
Piris
Adriano
A
Bersani
Ilaria
I
Vegetti
Claudia
C
Molla
Alessandra
A
Scarito
Alessia
A
Anichini
Andrea
A
D000578:Amidines / Q000494:pharmacology; D000970:Antineoplastic Agents / Q000494:pharmacology*; D017209:Apoptosis / Q000187:drug effects* / Q000502:physiology; D053477:Apoptotic Protease-Activating Factor 1; D001596:Benzylamines / Q000494:pharmacology; D002166:Camptothecin / Q000494:pharmacology; D053453:Caspase 9; D061945:Caspase Inhibitors; D020169:Caspases / Q000378:metabolism; D000068579:Celecoxib; D045744:Cell Line, Tumor; D004789:Enzyme Activation; D004791:Enzyme Inhibitors / Q000494:pharmacology; D006801:Humans; D007150:Immunohistochemistry; D008545:Melanoma / Q000188:drug therapy* / Q000378:metabolism / Q000473:pathology*; D014176:Protein Biosynthesis / Q000187:drug effects; D011506:Proteins / Q000235:genetics / Q000378:metabolism*; D011720:Pyrazoles; D012333:RNA, Messenger / Q000096:biosynthesis / Q000235:genetics; D013449:Sulfonamides / Q000494:pharmacology
C506592:APAF1 protein, human; D000578:Amidines; D000970:Antineoplastic Agents; D053477:Apoptotic Protease-Activating Factor 1; D001596:Benzylamines; D061945:Caspase Inhibitors; D004791:Enzyme Inhibitors; C104820:N-(3-(aminomethyl)benzyl)acetamidine; D011506:Proteins; D011720:Pyrazoles; D012333:RNA, Messenger; D013449:Sulfonamides; C506433:CASP9 protein, human; D053453:Caspase 9; D020169:Caspases; D000068579:Celecoxib; D002166:Camptothecin