Multiple effects of N-alpha-tosyl-L-phenylalanyl chloromethyl ketone (TPCK) on apoptotic pathways in human prostatic carcinoma cell lines.
TPCK is widely used as an inhibitor of chymotrypsin-like proteases but has recently been identified as an inhibitor of the PDK1/Akt pathway. In this study, we show that TPCK inhibits TRAIL-induced caspase activity but potentiates wortmannin-dependent caspase activity in prostatic carcinoma cell lines. The inhibitory activity of TPCK was found to be death ligand-specific since TPCK inhibits TRAIL-mediated caspase activity but does not affect Fas-induced caspase activity. Our data also show that impaired TRAIL-DISC formation in the presence of TPCK is responsible for caspase inhibition. Further, TPCK induces p53 expression and inhibits the PDK1/Akt pathway resulting in BAD dephosphorylation, and the release of cytochrome c and Smac/DIABLO from mitochondria. TPCK also selectively decreases the levels of androgen receptor and caspase-2 whereas it does not change the levels of other proteins (caspases-3, -7, -8, -9; heat shock proteins 27, 70, 90). Finally, TPCK-induced degradation of caspase-2 is protected by Bcl-2 overexpression, apparently by an adapter protein since direct interaction between caspase-2 and Bcl-2 was not detected. Together, these features suggest that TPCK could be used as a therapeutic agent for treatment of those tumor cells that are resistant to ligand-induced treatment because of aberrant signaling pathways downstream of the DISC.
Rokhlin
Oskar W
OW
Department of Pathology, The University of Iowa, Iowa City, Iowa 52242, USA. oskar-rokhlin@uiowa.edu
Guseva
Natalya V
NV
Taghiyev
Agshin F
AF
Glover
Rebecca A
RA
Cohen
Michael B
MB
D000477:Alkylating Agents / Q000494:pharmacology*; D000730:Androstadienes / Q000494:pharmacology; D000970:Antineoplastic Agents / Q000494:pharmacology; D017209:Apoptosis / Q000187:drug effects*; D051017:Apoptosis Regulatory Proteins; D020169:Caspases / Q000378:metabolism; D053418:Death Domain Receptor Signaling Adaptor Proteins; D006801:Humans; D008297:Male; D008562:Membrane Glycoproteins / Q000494:pharmacology; D000081082:Phosphoinositide-3 Kinase Inhibitors; D011471:Prostatic Neoplasms / Q000378:metabolism* / Q000473:pathology; D047428:Protein Kinase Inhibitors / Q000494:pharmacology; D019253:Proto-Oncogene Proteins c-bcl-2 / Q000378:metabolism; D018124:Receptors, Tumor Necrosis Factor / Q000378:metabolism; D015398:Signal Transduction / Q000187:drug effects*; D053221:TNF-Related Apoptosis-Inducing Ligand; D014108:Tosylphenylalanyl Chloromethyl Ketone / Q000494:pharmacology*; D014407:Tumor Cells, Cultured; D014409:Tumor Necrosis Factor-alpha / Q000494:pharmacology; D000077191:Wortmannin
D000477:Alkylating Agents; D000730:Androstadienes; D000970:Antineoplastic Agents; D051017:Apoptosis Regulatory Proteins; D053418:Death Domain Receptor Signaling Adaptor Proteins; D008562:Membrane Glycoproteins; D000081082:Phosphoinositide-3 Kinase Inhibitors; D047428:Protein Kinase Inhibitors; D019253:Proto-Oncogene Proteins c-bcl-2; D018124:Receptors, Tumor Necrosis Factor; D053221:TNF-Related Apoptosis-Inducing Ligand; C505653:TNFSF10 protein, human; D014409:Tumor Necrosis Factor-alpha; D014108:Tosylphenylalanyl Chloromethyl Ketone; D020169:Caspases; D000077191:Wortmannin