title: Nitric oxide sensitizes prostate carcinoma cell lines to TRAIL-mediated apoptosis via inactivation of NF-kappa B and inhibition of Bcl-xl expression.
abstract: Tumor necrosis factor-related apoptosis-inducing ligand (TRAIL) has been shown to be selective in the induction of apoptosis in cancer cells with minimal toxicity to normal tissues and this prompted its potential therapeutic application in cancer. However, not all cancers are sensitive to TRAIL-mediated apoptosis and, therefore, TRAIL-resistant cancer cells must be sensitized first to become sensitive to TRAIL. Treatment of prostate cancer (CaP) cell lines (DU145, PC-3, CL-1, and LNCaP) with nitric oxide donors (e.g. (Z)-1-[2-(2-aminoethyl)-N-(2-ammonio-ethyl)amino]diazen-1-ium-1, 2-diolate (DETANONOate)) sensitized CaP cells to TRAIL-induced apoptosis and synergy was achieved. The mechanism by which DETANONOate mediated the sensitization was examined. DETANONOate inhibited the constitutive NF-kappa B activity as assessed by EMSA. Also, p50 was S-nitrosylated by DETANONOate resulting in inhibition of NF-kappa B. Inhibition of NF-kappa B activity by the chemical inhibitor Bay 11-7085, like DETANONOate, sensitized CaP to TRAIL apoptosis. In addition, DETANONOate downregulated the expression of Bcl-2 related gene (Bcl-(xL)) which is under the transcriptional regulation of NF-kappa B. The regulation of NF-kappa B and Bcl-(xL) by DETANONOate was corroborated by the use of Bcl-(xL) and Bcl-x kappa B reporter systems. DETANONOate inhibited luciferase activity in the wild type and had no effect on the mutant cells. Inhibition of NF-kappa B resulted in downregulation of Bcl-(xL) expression and sensitized CaP to TRAIL-induced apoptosis. The role of Bcl-(xL) in the regulation of TRAIL apoptosis was corroborated by inhibiting Bcl-(xL) function by the chemical inhibitor 2-methoxyantimycin A(3) and this resulted in sensitization of the cells to TRAIL apoptosis. Signaling by DETANONOate and TRAIL for apoptosis was examined. DETANONOate altered the mitochondria by inducing membrane depolarization and releasing modest amounts of cytochrome c and Smac/DIABLO in the absence of downstream activation of caspases 9 and 3. However, the combination of DETANONOate and TRAIL resulted in activation of the mitochondrial pathway and activation of caspases 9 and 3, and induction of apoptosis. These findings demonstrate that DETANONOate-mediated sensitization of CaP to TRAIL-induced apoptosis is via inhibition of constitutive NF-kappa B activity and Bcl-(xL) expression.
authors.affiliation: Department of Microbiology, Immunology, and Molecular Genetics, David Geffen School of Medicine, University of California, Los Angeles, CA 90095, USA.
authors.forename: Sara
authors.initials: S
authors.lastname: Huerta-Yepez
authors.forename: Mario
authors.initials: M
authors.lastname: Vega
authors.forename: Ali
authors.initials: A
authors.lastname: Jazirehi
authors.forename: Hermes
authors.initials: H
authors.lastname: Garban
authors.forename: Fumiya
authors.initials: F
authors.lastname: Hongo
authors.forename: Genhong
authors.initials: G
authors.lastname: Cheng
authors.forename: Benjamin
authors.initials: B
authors.lastname: Bonavida
mesh_terms: D017209:Apoptosis; D051017:Apoptosis Regulatory Proteins; D015536:Down-Regulation; D006801:Humans; D008297:Male; D008562:Membrane Glycoproteins / Q000378:metabolism*; D052002:NF-kappa B p50 Subunit; D009569:Nitric Oxide / Q000494:pharmacology*; D009603:Nitroso Compounds / Q000494:pharmacology; D011471:Prostatic Neoplasms / Q000378:metabolism* / Q000473:pathology; D019253:Proto-Oncogene Proteins c-bcl-2 / Q000378:metabolism*; D053221:TNF-Related Apoptosis-Inducing Ligand; D014157:Transcription Factors / Q000378:metabolism*; D014407:Tumor Cells, Cultured; D014409:Tumor Necrosis Factor-alpha / Q000378:metabolism*; D051020:bcl-X Protein
chemical_list: D051017:Apoptosis Regulatory Proteins; C494811:BCL2L1 protein, human; D008562:Membrane Glycoproteins; D052002:NF-kappa B p50 Subunit; C489548:NFKB1 protein, human; D009603:Nitroso Compounds; D019253:Proto-Oncogene Proteins c-bcl-2; D053221:TNF-Related Apoptosis-Inducing Ligand; C505653:TNFSF10 protein, human; D014157:Transcription Factors; D014409:Tumor Necrosis Factor-alpha; D051020:bcl-X Protein; C094210:2,2'-(hydroxynitrosohydrazono)bis-ethanamine; D009569:Nitric Oxide