title: Caspase-3 activation and induction of PARP cleavage by cyclic dipeptide cyclo(Phe-Pro) in HT-29 cells.
abstract: BACKGROUND
  Cyclo(Phe-Pro) has been shown to inhibit cancer cell growth and induce apoptosis in HT-29 colon cancer cells.
  
  
  METHODS
  The molecular mechanisms mediating cyclo(Phe-Pro)-induced apoptosis in HT-29 cells were investigated. Cells were treated with 5 mM or 10 mM cyclo(Phe-Pro) for varying times. Immunoblot analysis was used to detect poly(ADP-ribose)polymerase (PARP) cleavage. A fluorescence-based enzymatic assay was used to measure caspase-3 activity.
  
  
  RESULTS
  Cyclo(Phe-Pro) (10 mM) induced time-dependent cleavage of PARP, detected as early as 8 hours post treatment. PARP cleavage was blocked by co-administration with the broad-range caspase inhibitor Z-VAD-FMK Cyclo(Phe-Pro) also induced a time-dependent increase (p < 0.01) in caspase-3 activity. This increase in activity was blocked in the presence of the caspase-3 inhibitor Ac-DEVD-CHO.
  
  
  CONCLUSIONS
  These results provide evidence that cyclo(Phe-Pro)-induced apoptosis in HT-29 cells is mediated by a caspase cascade. These findings warrant further investigation into the potential antitumour activity of cyclo(Phe-Pro) and its related cyclic dipeptide derivatives.
authors.affiliation: Department of Biochemistry and Microbiology, Nelson Mandela Metropolitan University, Port Elizabeth, 6031, South Africa.
authors.forename: Seth Clint
authors.initials: SC
authors.lastname: Brauns
authors.forename: Gill
authors.initials: G
authors.lastname: Dealtry
authors.forename: Pieter
authors.initials: P
authors.lastname: Milne
authors.forename: Ryno
authors.initials: R
authors.lastname: Naudé
authors.forename: Maryna
authors.initials: M
authors.lastname: Van de Venter
mesh_terms: D000590:Amino Acid Chloromethyl Ketones / Q000494:pharmacology; D018938:Caco-2 Cells; D053148:Caspase 3; D061945:Caspase Inhibitors; D020169:Caspases / Q000096:biosynthesis / Q000378:metabolism*; D015853:Cysteine Proteinase Inhibitors / Q000494:pharmacology; D004151:Dipeptides / Q000494:pharmacology* / Q000633:toxicity; D004789:Enzyme Activation / Q000187:drug effects; D004790:Enzyme Induction / Q000187:drug effects; D019073:HT29 Cells; D006801:Humans; D010456:Peptides, Cyclic / Q000494:pharmacology* / Q000633:toxicity; D011065:Poly(ADP-ribose) Polymerases / Q000378:metabolism*
chemical_list: D000590:Amino Acid Chloromethyl Ketones; D061945:Caspase Inhibitors; D015853:Cysteine Proteinase Inhibitors; D004151:Dipeptides; D010456:Peptides, Cyclic; C096713:benzyloxycarbonylvalyl-alanyl-aspartyl fluoromethyl ketone; C118540:cyclo(phenylalanyl-prolyl); D011065:Poly(ADP-ribose) Polymerases; C505407:CASP3 protein, human; D053148:Caspase 3; D020169:Caspases