title: SAHA-sensitized prostate cancer cells to TNFalpha-related apoptosis-inducing ligand (TRAIL): mechanisms leading to synergistic apoptosis.
abstract: Treatment of cancer cells with histone deacetylase inhibitors (HDACi) such as suberolylanilide hydroxamic acid (SAHA) activates genes that promote apoptosis. To enhance proapoptotic efficiency, SAHA has been used in combination with radiation, kinase inhibitors and cytotoxic drugs. Although several prostate cells respond to TNFalpha-Related Apoptosis-Inducing Ligand (TRAIL), LNCaP are resistant. This model system was utilized to examine the advantages of combined treatment with SAHA and TRAIL. In LNCaP cells, TRAIL induced synergistic apoptosis when combined even with the lowest dose of SAHA. Treatment with caspase inhibitor confirmed that SAHA-induced apoptosis was mediated through caspases. In addition to induction of apoptosis, SAHA and TRAIL decreased the levels of proapoptotic proteins IKKalpha, IKKbeta and IKKgamma, suggesting that SAHA treatment may reduce the activity of NFkappaB. However, assay for NFkappaB luciferase reporter activity showed highly significant increase in SAHA-treated cells, supporting earlier suggestions that HDACi promotes NFkappaB transcriptional activity. Further analyses to determine the mechanisms by which the combination of SAHA and TRAIL led to synergistic apoptosis indicated that the apoptotic response of LNCaP is due to a complex regulation of death receptor pathway and alterations of NFkappaB activity at several regulatory steps.
authors.affiliation: Department of Surgery, Medical College of Georgia, Augusta, GA 30912, USA.
authors.forename: Vijayabaskar
authors.initials: V
authors.lastname: Lakshmikanthan
authors.forename: Ismail
authors.initials: I
authors.lastname: Kaddour-Djebbar
authors.forename: Ronald W
authors.initials: RW
authors.lastname: Lewis
authors.forename: M Vijay
authors.initials: MV
authors.lastname: Kumar
mesh_terms: D000971:Antineoplastic Combined Chemotherapy Protocols / Q000494:pharmacology*; D017209:Apoptosis / Q000187:drug effects; D051017:Apoptosis Regulatory Proteins / Q000494:pharmacology*; D020169:Caspases / Q000187:drug effects / Q000378:metabolism; D045744:Cell Line, Tumor; D004357:Drug Synergism; D004791:Enzyme Inhibitors / Q000494:pharmacology; D006801:Humans; D006877:Hydroxamic Acids / Q000494:pharmacology*; D008156:Luciferases / Q000378:metabolism; D008297:Male; D008562:Membrane Glycoproteins / Q000494:pharmacology*; D016328:NF-kappa B / Q000378:metabolism; D011471:Prostatic Neoplasms / Q000188:drug therapy* / Q000378:metabolism / Q000473:pathology; D053221:TNF-Related Apoptosis-Inducing Ligand; D014409:Tumor Necrosis Factor-alpha / Q000494:pharmacology*; D000077337:Vorinostat
chemical_list: D051017:Apoptosis Regulatory Proteins; D004791:Enzyme Inhibitors; D006877:Hydroxamic Acids; D008562:Membrane Glycoproteins; D016328:NF-kappa B; D053221:TNF-Related Apoptosis-Inducing Ligand; C505653:TNFSF10 protein, human; D014409:Tumor Necrosis Factor-alpha; D000077337:Vorinostat; D008156:Luciferases; D020169:Caspases