Cyclooxygenase-2 up-regulates ataxia telangiectasia and Rad3 related through extracellular signal-regulated kinase activation.
Cyclooxygenase-2 (COX-2) overexpression caused prolonged G2 arrest after exposure to ionizing radiation (IR) in our previous study. We were therefore interested in investigating the function of COX-2 in the G2 checkpoint pathway. Interestingly, we found that cells in which COX-2 is overexpressed showed up-regulated ataxia telangiectasia and Rad3 related (ATR) expression compared with control cells. In this study, we investigated the mechanism of ATR up-regulation by COX-2 and tested our hypothesis that COX-2-induced extracellular signal-regulated kinase (ERK) activation mediates up-regulation of ATR by COX-2. To investigate the relationship between COX-2 and ATR, we used two stable COX-2-overexpressing cancer cell lines (HCT116-COX-2 and H460-COX-2), a COX-2 knockdown A549 lung cancer cell line (AS), and an ATR knockdown HCT116 cell line. Cells were treated with various drugs [celecoxib, prostaglandin E2 (PGE2), PD98059, U0126, and hydroxyurea] and were then analyzed using reverse transcription-PCR, confocal microscopy, Western blotting, and clonogenic assay. COX-2-overexpressing cells were shown to have increased ERK phosphorylation and ATR expression compared with control cells, whereas AS cells were shown to have decreased levels of phospho-ERK and ATR. In addition, exogenously administered PGE2 increased ERK phosphorylation. Inhibition of ERK phosphorylation decreased ATR expression in both HCT116-COX-2 and A549 cells. HCT116-COX-2 cells were resistant to IR or hydroxyurea compared with HCT116-Mock cells, whereas administration of ATR shRNA showed the opposite effect. COX-2 stimulates ERK phosphorylation via PGE2. This COX-2-induced ERK activation seems to increase ATR expression and activity in endogenous COX-2-overexpressing cancer cells as well as in COX-2-overexpressing stable cell lines.
Kim
Young Mee
YM
Research Institute and Hospital, National Cancer Center, Goyang, Gyeonggi, Republic of Korea.
Lee
Eun Jung
EJ
Park
Soo-Yeon
SY
Cho
Kwan Ho
KH
Kim
Joo Young
JY
Pyo
Hongryull
H
D064007:Ataxia Telangiectasia Mutated Proteins; D002070:Butadienes / Q000494:pharmacology; D000068579:Celecoxib; D018797:Cell Cycle Proteins / Q000096:biosynthesis* / Q000235:genetics / Q000378:metabolism; D045744:Cell Line, Tumor; D002470:Cell Survival; D000071877:Checkpoint Kinase 1; D051546:Cyclooxygenase 2 / Q000235:genetics / Q000378:metabolism*; D052246:Cyclooxygenase 2 Inhibitors / Q000494:pharmacology; D004249:DNA Damage; D003627:Data Interpretation, Statistical; D015232:Dinoprostone / Q000378:metabolism; D004791:Enzyme Inhibitors / Q000494:pharmacology; D048049:Extracellular Signal-Regulated MAP Kinases / Q000037:antagonists & inhibitors / Q000378:metabolism*; D006801:Humans; D009570:Nitriles / Q000494:pharmacology; D010766:Phosphorylation; D011494:Protein Kinases / Q000378:metabolism; D017346:Protein Serine-Threonine Kinases / Q000096:biosynthesis* / Q000235:genetics / Q000378:metabolism; D011720:Pyrazoles / Q000494:pharmacology; D015398:Signal Transduction / Q000187:drug effects; D013449:Sulfonamides / Q000494:pharmacology; D016159:Tumor Suppressor Protein p53 / Q000378:metabolism; D015854:Up-Regulation
D002070:Butadienes; D018797:Cell Cycle Proteins; D052246:Cyclooxygenase 2 Inhibitors; D004791:Enzyme Inhibitors; D009570:Nitriles; D011720:Pyrazoles; D013449:Sulfonamides; D016159:Tumor Suppressor Protein p53; C113580:U 0126; D051546:Cyclooxygenase 2; D011494:Protein Kinases; C576597:ATR protein, human; D064007:Ataxia Telangiectasia Mutated Proteins; D000071877:Checkpoint Kinase 1; D017346:Protein Serine-Threonine Kinases; D048049:Extracellular Signal-Regulated MAP Kinases; D000068579:Celecoxib; D015232:Dinoprostone