title: Poly(ADP-ribose) polymerase 1 modulates the lethality of CHK1 inhibitors in carcinoma cells.
abstract: Prior studies have demonstrated that inhibition of CHK1 can promote the activation of extracellular signal-regulated kinases 1 and 2 (ERK1/2) and phosphorylation of histone H2AX and that inhibition of poly(ADP-ribose) polymerase 1 (PARP1) can affect growth factor-induced ERK1/2 activation. The present studies were initiated to determine whether CHK1 inhibitors interacted with PARP1 inhibition to facilitate apoptosis. Transient expression of dominant-negative CHK1 raised basal ERK1/2 activity and prevented CHK1 inhibitors from activating ERK1/2. CHK1 inhibitors modestly increased the levels of PARP1 ADP ribosylation and molecular or small-molecule inhibition of PARP1 blocked CHK1 inhibitor-stimulated histone H2AX phosphorylation and activation of ERK1/2. Stimulated histone H2AX phosphorylation was ataxia telangiectasia-mutated protein-dependent. Multiple CHK1 inhibitors interacted in a greater than additive fashion with multiple PARP1 inhibitors to cause transformed cell-killing in short-term viability assays and synergistically killed tumor cells in colony-formation assays. Overexpression of BCL-xL or loss of BAX/BAK function, but not the function of BID, suppressed CHK1 inhibitor + PARP1 inhibitor lethality. Inhibition of BCL-2 family protein function enhanced CHK1 inhibitor + PARP1 inhibitor lethality and restored drug-induced cell-killing in cells overexpressing BCL-xL. Thus, PARP1 plays an important role in regulating the ability of CHK1 inhibitors to activate ERK1/2 and the DNA damage response. An inability of PARP1 to modulate this response results in transformed cell death mediated through the intrinsic apoptosis pathway.
authors.affiliation: Department of Neurosurgery, Virginia Commonwealth University, Richmond, VA 23298-0035, USA.
authors.forename: Clint
authors.initials: C
authors.lastname: Mitchell
authors.forename: Margaret
authors.initials: M
authors.lastname: Park
authors.forename: Patrick
authors.initials: P
authors.lastname: Eulitt
authors.forename: Chen
authors.initials: C
authors.lastname: Yang
authors.forename: Adly
authors.initials: A
authors.lastname: Yacoub
authors.forename: Paul
authors.initials: P
authors.lastname: Dent
mesh_terms: D016923:Cell Death / Q000187:drug effects; D045744:Cell Line, Tumor; D000071877:Checkpoint Kinase 1; D004357:Drug Synergism; D004789:Enzyme Activation; D006657:Histones / Q000378:metabolism; D006801:Humans; D019950:Mitogen-Activated Protein Kinase 1 / Q000378:metabolism; D048052:Mitogen-Activated Protein Kinase 3 / Q000378:metabolism; D010766:Phosphorylation; D000071137:Poly (ADP-Ribose) Polymerase-1; D000067856:Poly(ADP-ribose) Polymerase Inhibitors; D011065:Poly(ADP-ribose) Polymerases / Q000502:physiology*; D047428:Protein Kinase Inhibitors / Q000494:pharmacology*; D011494:Protein Kinases / Q000378:metabolism*; D015398:Signal Transduction / Q000187:drug effects; D019311:Staurosporine / Q000031:analogs & derivatives / Q000494:pharmacology; D013876:Thiophenes / Q000494:pharmacology; D014508:Urea / Q000031:analogs & derivatives / Q000494:pharmacology
chemical_list: C532363:3-(carbamoylamino)-5-(3-fluorophenyl)-N-(3-piperidyl)thiophene-2-carboxamide; C468783:H2AX protein, human; D006657:Histones; D000067856:Poly(ADP-ribose) Polymerase Inhibitors; D047428:Protein Kinase Inhibitors; D013876:Thiophenes; C054852:7-hydroxystaurosporine; D014508:Urea; C499320:PARP1 protein, human; D000071137:Poly (ADP-Ribose) Polymerase-1; D011065:Poly(ADP-ribose) Polymerases; D011494:Protein Kinases; C000605867:CHEK1 protein, human; D000071877:Checkpoint Kinase 1; D019950:Mitogen-Activated Protein Kinase 1; D048052:Mitogen-Activated Protein Kinase 3; D019311:Staurosporine