title: The chemopreventive agent phenethyl isothiocyanate sensitizes cells to Fas-mediated apoptosis.
abstract: The chemopreventive properties of the isothiocyanates have been attributed to their ability to inhibit phase I enzymes that activate procarcinogens, induce phase II protective enzymes and trigger apoptosis in transformed cells. In this study we provide evidence for a new mechanism of chemoprevention, wherein sublethal doses of phenethyl isothiocyanate (PEITC) sensitize cells to Fas-mediated apoptosis. The phenomenon was observed in the Fas-resistant T24 bladder carcinoma cell line and in Jurkat T cells overexpressing the anti-apoptotic protein Bcl-2. Caspase-3-like activity was increased up to 20-fold of that observed with either PEITC or anti-Fas antibody alone. While PEITC activated ERK, JNK and p38, inhibitors of these MAP kinases did not block apoptosis. PEITC transiently depleted cellular glutathione, providing a putative mechanism for sensitizing the cells to apoptosis. However, lowering glutathione with buthionine sulfoximine did not mimic the effect of PEITC. Instead, we propose that PEITC promotes apoptosis by directly modifying intracellular thiol proteins. The ability of PEITC to sensitize cells to receptor-mediated apoptosis provides an additional mechanism to explain its chemopreventive properties.
authors.affiliation: Free Radical Research Group, Department of Pathology, Christchurch School of Medicine and Health Sciences, PO Box 4345, Christchurch, New Zealand. juliet.pullar@chmeds.ac.nz
authors.forename: Juliet M
authors.initials: JM
authors.lastname: Pullar
authors.forename: Susan J
authors.initials: SJ
authors.lastname: Thomson
authors.forename: Monica J
authors.initials: MJ
authors.lastname: King
authors.forename: Christopher I
authors.initials: CI
authors.lastname: Turnbull
authors.forename: Robyn G
authors.initials: RG
authors.lastname: Midwinter
authors.forename: Mark B
authors.initials: MB
authors.lastname: Hampton
mesh_terms: D000444:Aldehyde Dehydrogenase / Q000037:antagonists & inhibitors; D016588:Anticarcinogenic Agents / Q000494:pharmacology*; D017209:Apoptosis / Q000187:drug effects*; D019328:Buthionine Sulfoximine / Q000494:pharmacology; D053148:Caspase 3; D020169:Caspases / Q000378:metabolism; D018890:Chemoprevention; D019008:Drug Resistance, Neoplasm; D006801:Humans; D017879:Isothiocyanates / Q000494:pharmacology*; D048031:JNK Mitogen-Activated Protein Kinases; D019169:Jurkat Cells; D048670:MAP Kinase Kinase 4; D019950:Mitogen-Activated Protein Kinase 1 / Q000378:metabolism; D048052:Mitogen-Activated Protein Kinase 3; D020929:Mitogen-Activated Protein Kinase Kinases / Q000378:metabolism; D020928:Mitogen-Activated Protein Kinases / Q000378:metabolism; D019253:Proto-Oncogene Proteins c-bcl-2 / Q000378:metabolism; D015398:Signal Transduction; D001749:Urinary Bladder Neoplasms / Q000378:metabolism / Q000473:pathology*; D019014:fas Receptor / Q000378:metabolism*; D048051:p38 Mitogen-Activated Protein Kinases
chemical_list: D016588:Anticarcinogenic Agents; D017879:Isothiocyanates; D019253:Proto-Oncogene Proteins c-bcl-2; D019014:fas Receptor; D019328:Buthionine Sulfoximine; C058305:phenethyl isothiocyanate; D000444:Aldehyde Dehydrogenase; D048031:JNK Mitogen-Activated Protein Kinases; D019950:Mitogen-Activated Protein Kinase 1; D048052:Mitogen-Activated Protein Kinase 3; D020928:Mitogen-Activated Protein Kinases; D048051:p38 Mitogen-Activated Protein Kinases; D048670:MAP Kinase Kinase 4; D020929:Mitogen-Activated Protein Kinase Kinases; C505407:CASP3 protein, human; D053148:Caspase 3; D020169:Caspases