Inhibition of ATR-dependent feedback activation of Chk1 sensitises cancer cells to Chk1 inhibitor monotherapy.
The Chk1 and ATR kinases are critical mediators of the DNA damage response pathway and help protect cancer cells from endogenous and oncogene induced replication stress. Inhibitors of both kinases are currently being evaluated in clinical trials. Chk1 inhibition with V158411 increases DNA damage and activates the ATR, ATM and DNA-PKcs dependent DNA damage response pathways. Inhibiting ATR, ATM and/or DNA-PKcs has the potential to increase the therapeutic activity of Chk1 inhibitors. ATR inhibition but not ATM or DNA-PKcs inhibition potentiated the cytotoxicity of V158411 in p53 mutant and wild type human cancer cell lines. This increased cytotoxicity correlated with increased nuclear DNA damage and replication stress in a dose and time dependent manner. γH2AX induction following Chk1 inhibition protected cells from caspase-dependent apoptosis. Inhibition of ATR increased Chk1 inhibitor induced cell death independently of caspase activation. The effect of ATR, ATM and/or DNA-PK inhibition on Chk1 inhibitor induced replication stress was dependent on the concentration of Chk1 inhibitor. ATR inhibition potentiated Chk1 inhibitor induced replication stress and cytotoxicity via the abrogation of ATR-dependent feedback activation of Chk1 induced by Chk1 inhibitor generated replication stress. This study suggests that combining an ATR inhibitor to lower the threshold by which a Chk1 inhibitor induces replication stress, DNA damage and tumour cell death in a wide range of cancer types may be a useful clinical approach.
Vernalis Research, Granta Park, Cambridge, CB21 6GB, UK. Electronic address: a.massey@vernalis.com.
Andrew J
AJ
Massey
D000971:Antineoplastic Combined Chemotherapy Protocols / Q000494:pharmacology*; D017209:Apoptosis / Q000187:drug effects; D064007:Ataxia Telangiectasia Mutated Proteins / Q000037:antagonists & inhibitors / Q000378:metabolism; D001859:Bone Neoplasms / Q000188:drug therapy* / Q000201:enzymology / Q000235:genetics / Q000473:pathology; D049109:Cell Proliferation / Q000187:drug effects; D000071877:Checkpoint Kinase 1 / Q000037:antagonists & inhibitors* / Q000378:metabolism; D015179:Colorectal Neoplasms / Q000188:drug therapy* / Q000201:enzymology / Q000235:genetics / Q000473:pathology; D004249:DNA Damage; D051747:DNA-Activated Protein Kinase / Q000037:antagonists & inhibitors / Q000378:metabolism; D004305:Dose-Response Relationship, Drug; D019073:HT29 Cells; D006657:Histones / Q000378:metabolism; D006801:Humans; D007211:Indoles / Q000494:pharmacology*; D007555:Isoxazoles / Q000494:pharmacology*; D058990:Molecular Targeted Therapy; D009687:Nuclear Proteins / Q000037:antagonists & inhibitors / Q000378:metabolism; D012516:Osteosarcoma / Q000188:drug therapy* / Q000201:enzymology / Q000235:genetics / Q000473:pathology; D047428:Protein Kinase Inhibitors / Q000494:pharmacology*; D011719:Pyrazines / Q000494:pharmacology*; D011728:Pyridones / Q000494:pharmacology*; D015398:Signal Transduction / Q000187:drug effects; D013997:Time Factors
C468783:H2AX protein, human; D006657:Histones; D007211:Indoles; D007555:Isoxazoles; D009687:Nuclear Proteins; D047428:Protein Kinase Inhibitors; D011719:Pyrazines; D011728:Pyridones; C000596547:V158411; C576597:ATR protein, human; D064007:Ataxia Telangiectasia Mutated Proteins; C000605867:CHEK1 protein, human; D000071877:Checkpoint Kinase 1; D051747:DNA-Activated Protein Kinase; C497263:PRKDC protein, human; C000598331:berzosertib
ATM; ATR; Chk1; DNA-PK; Kinase inhibitor; Replication stress