title: Butyrate mediates Caco-2 cell apoptosis via up-regulation of pro-apoptotic BAK and inducing caspase-3 mediated cleavage of poly-(ADP-ribose) polymerase (PARP).
abstract: Butyrate exerts potent anti-tumor effects by inhibiting cancer cell growth and inducing apoptosis. However, the molecular mechanisms mediating these effects remain largely unknown. Using the Caco-2 cell line, a well established model of colon cancer cells, our data show that butyrate induced apoptosis (maximum 79%) is mediated via activation of the caspase-cascade. A key event was the proteolytic activation of caspase-3, triggering degradation of poly-(ADP-ribose) polymerase (PARP). Inactivation of caspase-3 with the tetrapeptide zDEVD-FMK completely inhibited the apoptotic response to butyrate. In parallel, butyrate potently up-regulated the expression of the pro-apoptotic protein bak, without changing Caco-2 cell bcl-2 expression. Butyrate-induced Caco-2 cell apoptosis was completely blocked by the addition of cycloheximide, indicating the necessity of protein synthesis. However, when this inhibitor was added at a time point where bak expression was already enhanced (12 - 16 h after butyrate stimulation), it failed to protect Caco-2 cells against apoptosis. Taken together, these data provide evidence that the molecular events involved in butyrate induced colon cancer cell apoptosis include the caspase-cascade and the mitochondrial bcl-pathway.
authors.affiliation: Department of Pediatrics, Intestinal Immunology Laboratory, Ste. Justine Hospital, University of Montreal, Quebec, Canada.
authors.forename: F M
authors.initials: FM
authors.lastname: Ruemmele
authors.forename: S
authors.initials: S
authors.lastname: Dionne
authors.forename: I
authors.initials: I
authors.lastname: Qureshi
authors.forename: D S
authors.initials: DS
authors.lastname: Sarma
authors.forename: E
authors.initials: E
authors.lastname: Levy
authors.forename: E G
authors.initials: EG
authors.lastname: Seidman
mesh_terms: D017209:Apoptosis / Q000187:drug effects; D002087:Butyrates / Q000378:metabolism* / Q000494:pharmacology; D018938:Caco-2 Cells; D053148:Caspase 3; D020169:Caspases / Q000096:biosynthesis / Q000378:metabolism*; D002455:Cell Division; D003513:Cycloheximide / Q000494:pharmacology; D015853:Cysteine Proteinase Inhibitors / Q000494:pharmacology; D004789:Enzyme Activation; D004790:Enzyme Induction; D006801:Humans; D008565:Membrane Proteins / Q000096:biosynthesis*; D009842:Oligopeptides / Q000494:pharmacology; D011065:Poly(ADP-ribose) Polymerases / Q000378:metabolism*; D014176:Protein Biosynthesis; D011500:Protein Synthesis Inhibitors / Q000494:pharmacology; D019253:Proto-Oncogene Proteins c-bcl-2 / Q000096:biosynthesis*; D015854:Up-Regulation; D050998:bcl-2 Homologous Antagonist-Killer Protein
chemical_list: C494772:BAK1 protein, human; D002087:Butyrates; D015853:Cysteine Proteinase Inhibitors; D008565:Membrane Proteins; D009842:Oligopeptides; D011500:Protein Synthesis Inhibitors; D019253:Proto-Oncogene Proteins c-bcl-2; D050998:bcl-2 Homologous Antagonist-Killer Protein; C110772:benzoylcarbonyl-aspartyl-glutamyl-valyl-aspartyl-fluoromethyl ketone; D003513:Cycloheximide; D011065:Poly(ADP-ribose) Polymerases; C505407:CASP3 protein, human; D053148:Caspase 3; D020169:Caspases