Inhibition of CHK1 kinase by Gö6976 converts 8-chloro-adenosine-induced G2/M arrest into S arrest in human myelocytic leukemia K562 cells.
8-Chloro-cAMP (8-Cl-cAMP) and its metabolite 8-chloro-adenosine (8-Cl-Ado) inhibit cell growth by 8-Cl-Ado-converted 8-Cl-ATP that targets cell-cycle control and RNA metabolism. However, the cell-cycle checkpoint pathways remain to be identified. Recent studies have shown that 8-Cl-cAMP administration and 8-Cl-Ado exposure may damage chromosomal DNA in vivo and in vitro. In this study, we demonstrate that 8-Cl-Ado-induced DNA damage activates G2/M phase checkpoint, which is associated with ATM-activated CHK1-CDC25C-CDC2 pathway joined by BRCA1-CHK1 branch in apoptosis-resistant human myelocytic leukemia K562 (p53-null) cells. Inhibition of CHK1 kinase by Gö6976, an inhibitor of CHK1 activity, can promote DNA damage and lead to the activation of CHK2, converting G2/M checkpoint into intra-S-phase checkpoint in which two parallel branches, the ATM-CHK2-CDC25A-CDK2 and the ATM-NBS1/SMC1 cascades, are involved. These observations may provide aid in better understanding of the mechanisms of 8-Cl-cAMP and 8-Cl-Ado actions and in potential design of the combined therapy.
Jia
Xiu-Zhen
XZ
Department of Biochemistry and Molecular Biology, Peking University Health Science Center, Xue Yuan Road 38, Beijing 100191, PR China.
Yang
Sheng-Yong
SY
Zhou
Jing
J
Li
Shu-Yan
SY
Ni
Ju-Hua
JH
An
Guo-Shun
GS
Jia
Hong-Ti
HT
D015762:2-Chloroadenosine / Q000031:analogs & derivatives* / Q000494:pharmacology; D064007:Ataxia Telangiectasia Mutated Proteins; D019313:BRCA1 Protein / Q000378:metabolism; D015153:Blotting, Western; D002227:Carbazoles / Q000494:pharmacology*; D018797:Cell Cycle Proteins / Q000378:metabolism; D002455:Cell Division / Q000187:drug effects*; D000071877:Checkpoint Kinase 1; D004268:DNA-Binding Proteins / Q000378:metabolism; D005434:Flow Cytometry; D016195:G2 Phase / Q000187:drug effects*; D006801:Humans; D007150:Immunohistochemistry; D047468:Immunoprecipitation; D020014:K562 Cells; D047428:Protein Kinase Inhibitors / Q000494:pharmacology*; D011494:Protein Kinases / Q000187:drug effects*; D017346:Protein Serine-Threonine Kinases / Q000378:metabolism; D018741:Replication Origin / Q000187:drug effects; D016196:S Phase / Q000187:drug effects*; D025521:Tumor Suppressor Proteins / Q000378:metabolism
D019313:BRCA1 Protein; D002227:Carbazoles; D018797:Cell Cycle Proteins; D004268:DNA-Binding Proteins; D047428:Protein Kinase Inhibitors; D025521:Tumor Suppressor Proteins; C081021:Go 6976; D015762:2-Chloroadenosine; D011494:Protein Kinases; C576324:ATM protein, human; D064007:Ataxia Telangiectasia Mutated Proteins; C000605867:CHEK1 protein, human; D000071877:Checkpoint Kinase 1; D017346:Protein Serine-Threonine Kinases; C075440:8-chloroadenosine