title: The molecular mechanism of sensitization to Fas-mediated apoptosis by 2-methoxyestradiol in PC3 prostate cancer cells.
abstract: It is widely known that death receptor Fas-dependent apoptotic signals are associated with development of prostate cancer, but the key pathways involved in sensitivity to the apoptosis remain unclear. Here we investigated the molecular mechanism by which 2-methoxyestradiol (2-ME) effectively sensitizes a human prostate cancer cell line, PC3, to Fas-mediated apoptosis. 2-ME significantly inhibited nuclear factor-kappaB (NF-kappaB) activation and downregulated Fas-associated death domain (FADD) protein interluekin-1beta-converting enzyme inhibitory protein (FLIP). Overexpression of the dominant negative mutant form of IkappaBalpha (d/n IkappaBalpha) or treatment with Ikappa kinase-specific inhibitor Bay117082 gave the same results, although the sensitizing effect was not as pronounced. A selective inhibitor of Akt phosphorylation, LY294002, accelerated formation of the death-inducing signaling complex (DISC) not only by FLIP reduction but also by enhancement of recruitment of the FADD to Fas, thereby sensitizing PC3 cells to apoptosis similar to the case with 2-ME stimulation. Moreover, we found that inhibition of 2-ME-induced extracellular signal-regulated kinase (ERK) activation by the upstream kinase inhibitor PD98059 significantly enhanced 2-ME-mediated suppression of Akt activation, resulting in much greater sensitization to apoptosis. Taken together, the present findings indicate that 2-ME suppresses NF-kappaB/FLIP signaling and enhances DISC formation through inhibition of Akt, and that PC3 cells thereby are being sensitized to Fas-mediated apoptosis and by a process closely associated with ERK.
authors.affiliation: Department of Pathology, Nara Medical University, Nara, Japan.
authors.forename: Keiji
authors.initials: K
authors.lastname: Shimada
authors.forename: Mitsutoshi
authors.initials: M
authors.lastname: Nakamura
authors.forename: Eiwa
authors.initials: E
authors.lastname: Ishida
authors.forename: Munehiro
authors.initials: M
authors.lastname: Kishi
authors.forename: Syuchi
authors.initials: S
authors.lastname: Matsuyoshi
authors.forename: Noboru
authors.initials: N
authors.lastname: Konishi
mesh_terms: D000077584:2-Methoxyestradiol; D017209:Apoptosis / Q000187:drug effects*; D029681:Arabidopsis Proteins / Q000378:metabolism; D053446:CASP8 and FADD-Like Apoptosis Regulating Protein; D002352:Carrier Proteins / Q000378:metabolism; D002867:Chromones / Q000494:pharmacology; D053418:Death Domain Receptor Signaling Adaptor Proteins; D019008:Drug Resistance, Neoplasm; D024202:Electrophoretic Mobility Shift Assay; D004789:Enzyme Activation; D004791:Enzyme Inhibitors / Q000494:pharmacology; D004958:Estradiol / Q000031:analogs & derivatives* / Q000494:pharmacology*; D044943:Fatty Acid Desaturases / Q000378:metabolism; D005419:Flavonoids / Q000494:pharmacology; D005799:Genes, Dominant; D006801:Humans; D020672:I-kappa B Proteins / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism; D047908:Intracellular Signaling Peptides and Proteins; D008156:Luciferases / Q000378:metabolism; D008297:Male; D020928:Mitogen-Activated Protein Kinases / Q000037:antagonists & inhibitors; D009025:Morpholines / Q000494:pharmacology; D000072000:NF-KappaB Inhibitor alpha; D016328:NF-kappa B / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism; D009570:Nitriles; D009930:Organic Chemicals / Q000494:pharmacology; D010766:Phosphorylation; D011471:Prostatic Neoplasms / Q000188:drug therapy / Q000378:metabolism* / Q000473:pathology; D017346:Protein Serine-Threonine Kinases; D011518:Proto-Oncogene Proteins / Q000037:antagonists & inhibitors; D051057:Proto-Oncogene Proteins c-akt; D018124:Receptors, Tumor Necrosis Factor; D015398:Signal Transduction; D013450:Sulfones; D014407:Tumor Cells, Cultured; D019014:fas Receptor / Q000378:metabolism*
chemical_list: C434003:3-(4-methylphenylsulfonyl)-2-propenenitrile; D029681:Arabidopsis Proteins; D053446:CASP8 and FADD-Like Apoptosis Regulating Protein; C506386:CFLAR protein, human; D002352:Carrier Proteins; D002867:Chromones; D053418:Death Domain Receptor Signaling Adaptor Proteins; D004791:Enzyme Inhibitors; D005419:Flavonoids; D020672:I-kappa B Proteins; D047908:Intracellular Signaling Peptides and Proteins; D009025:Morpholines; D016328:NF-kappa B; C000606204:NFKBIA protein, human; D009570:Nitriles; D009930:Organic Chemicals; D011518:Proto-Oncogene Proteins; D018124:Receptors, Tumor Necrosis Factor; D013450:Sulfones; D019014:fas Receptor; D000072000:NF-KappaB Inhibitor alpha; C085911:2-(4-morpholinyl)-8-phenyl-4H-1-benzopyran-4-one; D004958:Estradiol; D000077584:2-Methoxyestradiol; D008156:Luciferases; D044943:Fatty Acid Desaturases; C084083:Fad7 protein, Arabidopsis; C494918:AKT1 protein, human; D017346:Protein Serine-Threonine Kinases; D051057:Proto-Oncogene Proteins c-akt; D020928:Mitogen-Activated Protein Kinases; C093973:2-(2-amino-3-methoxyphenyl)-4H-1-benzopyran-4-one