Antisense inhibition of Chk2/hCds1 expression attenuates DNA damage-induced S and G2 checkpoints and enhances apoptotic activity in HEK-293 cells.
The cellular response to DNA damage involves checkpoint controls that delay cell cycle progression in order to provide time for repair of damaged DNA. Chk2/hCds1 is a recently identified homolog of the yeast Cds1 kinase that is involved in cell cycle checkpoint response to DNA damage. To investigate the functions of Chk2/hCds1 in response to DNA damage in mammalian cells, we established a stable human kidney embryonic cell line (HEK-293) that expresses antisense Chk2/hCds1 (Chk2AS) under the control of an inducible promoter. Cells that express Chk2AS display defective S-phase delay in response to DNA replication-mediated DNA damage induced by the topoisomerase I inhibitor camptothecin. The defective G2 checkpoint was also observed in Chk2AS cells exposed to the DNA damaging agent VP-16 or gamma-radiation. Enhanced apoptosis was observed in Chk2AS cells after exposure to gamma-radiation or camptothecin. No p53 activation was observed after DNA damage in HEK-293 or Chk2AS cells. Our results indicate that perturbation of Chk2/hCds1 expression adversely affects the S- and G2-phase checkpoints following DNA damage or DNA replication block, and suggest that reduced expression of Chk2/hCds1 might promote a p53-independent apoptotic response.
Yu
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Laboratory of Molecular Pharmacology, Center for Cancer Research, National Cancer Institute, National Institutes of Health, Bldg. 37, Rm. 4E28, Bethesda, MD 20892-4255, USA.
Rose
J H
JH
Zhang
H
H
Pommier
Y
Y
D017209:Apoptosis / Q000235:genetics*; D002478:Cells, Cultured; D064447:Checkpoint Kinase 2; D004249:DNA Damage / Q000502:physiology*; D016373:DNA, Antisense; D016195:G2 Phase / Q000235:genetics*; D005786:Gene Expression Regulation; D006801:Humans; D007668:Kidney / Q000166:cytology / Q000196:embryology; D011494:Protein Kinases / Q000235:genetics* / Q000378:metabolism; D017346:Protein Serine-Threonine Kinases; D016196:S Phase / Q000235:genetics*; D014162:Transfection; D016159:Tumor Suppressor Protein p53 / Q000235:genetics / Q000378:metabolism
D016373:DNA, Antisense; D016159:Tumor Suppressor Protein p53; D011494:Protein Kinases; D064447:Checkpoint Kinase 2; C578634:CHEK2 protein, human; D017346:Protein Serine-Threonine Kinases