title: Different molecular events account for butyrate-induced apoptosis in two human colon cancer cell lines.
abstract: We studied the molecular events underlying butyrate-induced apoptosis in two different colon cancer cell lines: Caco-2, a well defined cancer cell and RSB, a cell line obtained from a colonic tumor of an ulcerative colitis patient. Caco-2 and RSB cells were exposed to 2, 5 and 10 mmol/L butyrate for 48 h. Caspase-1 was cleaved in Caco-2-cells at all butyrate concentrations, whereas in RSB-cells caspase-1 expression was undetectable. In RSB cells, butyrate dose-dependently induced caspase-3 cleavage, whereas in Caco-2-cells, butyrate up-regulated expression of the caspase-3 active subunit. Caspase-3-specific activity, cytoplasmic nucleosome concentration and growth were directly correlated with butyrate doses in both cell lines; however, the response was more pronounced in Caco-2 than in RSB cells. Expression of the cleaved poly(ADP-ribose) polymerase (PARP) product was elevated in both cell lines at the highest butyrate concentration. Bak expression gradually increased as a function of butyrate concentrations in both cell lines. At 10 mmol/L butyrate, expression increased by fivefold and sevenfold in Caco-2 and RSB cells, respectively. The highest expression of Bcl-2 was observed in control Caco-2 cells, and expression decreased with increasing butyrate concentration. This effect was not observed in RSB cells. Inactivation of caspase-1 with Z-YVAD-FMK abrogated butyrate-induced apoptosis in Caco-2 but not in RSB cells. Inactivation of caspase-3 with Z-DVED-FMK completely inhibited butyrate-induced apoptosis in RSB cells whereas this effect was less pronounced in Caco-2 cells. Our data demonstrate that butyrate-induced apoptosis is activated via different apoptotic pathways in diversely stratified colon cancers.
authors.affiliation: Institute of Biochemistry, Food Science and Nutrition, Faculty of Agricultural, Food and Environmental Quality Sciences, The Hebrew University of Jerusalem, Rehovot 76100, Israel.
authors.forename: Carmel
authors.initials: C
authors.lastname: Avivi-Green
authors.forename: Sylvie
authors.initials: S
authors.lastname: Polak-Charcon
authors.forename: Zecharia
authors.initials: Z
authors.lastname: Madar
authors.forename: Betty
authors.initials: B
authors.lastname: Schwartz
mesh_terms: D000590:Amino Acid Chloromethyl Ketones / Q000494:pharmacology; D017209:Apoptosis / Q000502:physiology*; D015153:Blotting, Western; D002087:Butyrates / Q000494:pharmacology*; D018938:Caco-2 Cells / Q000187:drug effects; D053148:Caspase 3; D061945:Caspase Inhibitors; D020169:Caspases / Q000378:metabolism; D002455:Cell Division / Q000187:drug effects; D003110:Colonic Neoplasms / Q000473:pathology / Q000503:physiopathology* / Q000648:ultrastructure; D015853:Cysteine Proteinase Inhibitors; D006801:Humans; D008565:Membrane Proteins / Q000378:metabolism; D009707:Nucleosomes / Q000378:metabolism; D009842:Oligopeptides / Q000494:pharmacology; D011065:Poly(ADP-ribose) Polymerases / Q000378:metabolism; D019253:Proto-Oncogene Proteins c-bcl-2 / Q000378:metabolism; D014407:Tumor Cells, Cultured / Q000187:drug effects; D050998:bcl-2 Homologous Antagonist-Killer Protein
chemical_list: D000590:Amino Acid Chloromethyl Ketones; C494772:BAK1 protein, human; D002087:Butyrates; D061945:Caspase Inhibitors; D015853:Cysteine Proteinase Inhibitors; D008565:Membrane Proteins; D009707:Nucleosomes; D009842:Oligopeptides; D019253:Proto-Oncogene Proteins c-bcl-2; D050998:bcl-2 Homologous Antagonist-Killer Protein; C110772:benzoylcarbonyl-aspartyl-glutamyl-valyl-aspartyl-fluoromethyl ketone; C460579:benzyloxycarbonyltyrosyl-valyl-alanyl-aspartic acid fluoromethyl ketone; D011065:Poly(ADP-ribose) Polymerases; C505407:CASP3 protein, human; D053148:Caspase 3; D020169:Caspases