title: Sodium butyrate sensitizes human colon adenocarcinoma COLO 205 cells to both intrinsic and TNF-alpha-dependent extrinsic apoptosis.
abstract: Overexpression of cFLIP protein seems to be critical in the antiapoptotic mechanism of immune escape of human COLO 205 colon adenocarcinoma cells. Actually, cFLIP appears to inhibit the death receptor ligand-mediated cell death. Application of the metabolic inhibitor sodium butyrate (NaBt), short-chain volatile fatty acid, sensitized COLO 205 cells to TNF-alpha-mediated apoptosis. Western-blot analysis revealed that the susceptibility of human COLO 205 cells to apoptogenic stimuli resulted from time-dependent reduction in cFLIP and simultaneous up-regulation of TNF-R1 protein levels. Additionally, the combined TNF-alpha and NaBt treatment caused cleavage of Bid and caspase-9 activation, as well as cytochrome c release from mitochondria. Thus, the evidence of this study indicates that NaBt facilitates the death receptor signal evoked by TNF-alpha. Moreover, NaBt alone initiated intrinsic apoptosis, that in turn was abolished by intracellular BCL-2 delivery. It confirms the involvement of mitochondria in the proapoptotic activity of NaBt. The activation of mitochondrial pathway was substantiated by up-regulated expression of BAK with concomitant reduction of antiapoptotic BCL-x(L), XIAP and survivin proteins. These findings suggest that NaBt could represent a good candidate for the new therapeutic strategy aimed to improve chemo- and immunotherapy of colon cancer.
authors.affiliation: Department of Cell Ultrastructure, Mossakowski Medical Research Center, Polish Academy of Sciences, Pawinskiego 5, 02-106 Warsaw, Poland. bepaj@wp.pl
authors.forename: Beata
authors.initials: B
authors.lastname: Pajak
authors.forename: Barbara
authors.initials: B
authors.lastname: Gajkowska
authors.forename: Arkadiusz
authors.initials: A
authors.lastname: Orzechowski
mesh_terms: D017209:Apoptosis / Q000187:drug effects*; D051017:Apoptosis Regulatory Proteins / Q000378:metabolism; D002087:Butyrates / Q000494:pharmacology*; D053446:CASP8 and FADD-Like Apoptosis Regulating Protein / Q000378:metabolism; D045744:Cell Line, Tumor; D003110:Colonic Neoplasms / Q000473:pathology* / Q000648:ultrastructure; D004354:Drug Screening Assays, Antitumor; D004357:Drug Synergism; D006801:Humans; D008928:Mitochondria / Q000187:drug effects / Q000378:metabolism; D016328:NF-kappa B / Q000378:metabolism; D047888:Receptors, Tumor Necrosis Factor, Type I / Q000378:metabolism; D014409:Tumor Necrosis Factor-alpha / Q000494:pharmacology*; D015854:Up-Regulation / Q000187:drug effects
chemical_list: D051017:Apoptosis Regulatory Proteins; D002087:Butyrates; D053446:CASP8 and FADD-Like Apoptosis Regulating Protein; C506386:CFLAR protein, human; D016328:NF-kappa B; D047888:Receptors, Tumor Necrosis Factor, Type I; D014409:Tumor Necrosis Factor-alpha