title: PARP-1-induced cell death through inhibition of the MEK/ERK pathway in MNNG-treated HeLa cells.
abstract: Poly(ADP-ribose) polymerase-1 (PARP-1) hyper-activation promotes cell death but the signaling events downstream of PARP-1 activation are not fully identified. To gain further information on the implication of PARP-1 activation and PAR synthesis on signaling pathways influencing cell death, we exposed HeLa cells to the DNA alkylating agent N-methyl-N'-methyl-nitro-N-nitrosoguanidine (MNNG). We found that massive PAR synthesis leads to down-regulation of ERK1/2 phosphorylation, Bax translocation to the mitochondria, release of cytochrome c and AIF and subsequently cell death. Inhibition of massive PAR synthesis following MNNG exposure with the PARP inhibitor PJ34 prevented those events leading to cell survival, whereas inhibition of ERK1/2 phosphorylation by inhibiting MEK counteracted the cytoprotective effect of PJ34. Together, our results provide evidence that PARP-1-induced cell death by MNNG exposure in HeLa cells is mediated in part through inhibition of the MEK/ERK signaling pathway and that inhibition of massive PAR synthesis by PJ34, which promotes sustained activation of ERK1/2, leads to cytoprotection.
authors.affiliation: Health and Environment Unit, Laval University Medical Research Center, CHUQ, Faculty of Medicine, Laval University, 2705, Boulevard Laurier, Quebec City, QC, Canada G1V 4G2.
authors.forename: Chantal
authors.initials: C
authors.lastname: Ethier
authors.forename: Yves
authors.initials: Y
authors.lastname: Labelle
authors.forename: Guy G
authors.initials: GG
authors.lastname: Poirier
mesh_terms: D017209:Apoptosis / Q000187:drug effects* / Q000502:physiology; D048049:Extracellular Signal-Regulated MAP Kinases / Q000037:antagonists & inhibitors* / Q000502:physiology; D005260:Female; D006367:HeLa Cells; D006801:Humans; D020935:MAP Kinase Signaling System / Q000187:drug effects* / Q000502:physiology; D008769:Methylnitronitrosoguanidine / Q000494:pharmacology*; D020929:Mitogen-Activated Protein Kinase Kinases / Q000037:antagonists & inhibitors* / Q000502:physiology; D000071137:Poly (ADP-Ribose) Polymerase-1; D011065:Poly(ADP-ribose) Polymerases / Q000502:physiology*; D002583:Uterine Cervical Neoplasms / Q000201:enzymology* / Q000473:pathology*