title: The checkpoint 1 kinase inhibitor LY2603618 induces cell cycle arrest, DNA damage response and autophagy in cancer cells.
abstract: Chemotherapy- or radiotherapy-induced DNA damage activates the Chk1-dependent DNA damage response (DDR) and cell cycle checkpoints to facilitate cell survival. Numerous attempts have been made to identify specific Chk1 inhibitors to enhance the efficiency of chemotherapy or radiotherapy. In this study, we investigated the molecular mechanisms underlying the antitumor activity of LY2603618, a potent and selective small molecule inhibitor of Chk1 protein kinase, in human lung cancer cells. Treatment of cancer cells with LY2603618 caused cell cycle arrest in the G2/M phase. A marked induction of DDR, including the phosphorylation of ATM, Chk2, p53 and histone H2AX, was observed after LY2603618 treatment. LY2603618 inhibited Chk1 autophosphorylation (S296 Chk1) and increased DNA damage-mediated Chk1 phosphorylation (S345 Chk1). In addition, LY2603618-treated lung cancer cells transitioned from LC3-I to LC3-II, a hallmark of autophagy. Blocking autophagy with chloroquine (CQ) further enhanced LY2603618's inhibitory effect on cell viability/proliferation. LY2603618 also significantly increased p38 and c-Jun N-terminal kinase (JNK) phosphorylation. Pretreatment with the JNK inhibitor reduced cleavage of caspase-3 and PARP levels in LY2603618-treated cells. These results suggest the following: (i) the biological consequences of LY2603618 in lung cancer cells is associated with both inhibition of Chk1 phosphorylation on S296 and activation of the DNA damage response network; and (ii) the anticancer property of LY2603618 might be increased by inhibiting autophagy.
authors.affiliation: School of Biological Science, Taishan Medical University, Taian, 271016, People's Republic of China.
authors.forename: Feng-Ze
authors.initials: FZ
authors.lastname: Wang
authors.forename: Hong-rong
authors.initials: HR
authors.lastname: Fei
authors.forename: Ying-Jie
authors.initials: YJ
authors.lastname: Cui
authors.forename: Ying-Kun
authors.initials: YK
authors.lastname: Sun
authors.forename: Zhao-Mei
authors.initials: ZM
authors.lastname: Li
authors.forename: Xue-Ying
authors.initials: XY
authors.lastname: Wang
authors.forename: Xiao-Yi
authors.initials: XY
authors.lastname: Yang
authors.forename: Ji-Guo
authors.initials: JG
authors.lastname: Zhang
authors.forename: Bao-Liang
authors.initials: BL
authors.lastname: Sun
mesh_terms: D000970:Antineoplastic Agents / Q000494:pharmacology*; D018501:Antirheumatic Agents / Q000494:pharmacology; D001343:Autophagy / Q000187:drug effects*; D002289:Carcinoma, Non-Small-Cell Lung; D020169:Caspases / Q000378:metabolism; D045744:Cell Line, Tumor / Q000187:drug effects; D049109:Cell Proliferation / Q000187:drug effects; D002470:Cell Survival / Q000187:drug effects; D000071877:Checkpoint Kinase 1; D002738:Chloroquine / Q000494:pharmacology; D004249:DNA Damage; D004260:DNA Repair / Q000187:drug effects*; D059565:G2 Phase Cell Cycle Checkpoints; D006801:Humans; D008175:Lung Neoplasms; D048670:MAP Kinase Kinase 4 / Q000378:metabolism; D009687:Nuclear Proteins / Q000378:metabolism; D010671:Phenylurea Compounds / Q000494:pharmacology*; D010766:Phosphorylation / Q000187:drug effects; D047428:Protein Kinase Inhibitors / Q000494:pharmacology*; D011494:Protein Kinases / Q000378:metabolism*; D011719:Pyrazines / Q000494:pharmacology*; D012694:Serine / Q000378:metabolism; D048051:p38 Mitogen-Activated Protein Kinases / Q000378:metabolism
chemical_list: D000970:Antineoplastic Agents; D018501:Antirheumatic Agents; C582547:LY2603618; D009687:Nuclear Proteins; D010671:Phenylurea Compounds; D047428:Protein Kinase Inhibitors; D011719:Pyrazines; D012694:Serine; D002738:Chloroquine; D011494:Protein Kinases; C000605867:CHEK1 protein, human; D000071877:Checkpoint Kinase 1; D048051:p38 Mitogen-Activated Protein Kinases; D048670:MAP Kinase Kinase 4; D020169:Caspases