Radiation induces upregulation of cyclooxygenase-2 (COX-2) protein in PC-3 cells.
OBJECTIVE
To investigate the impact of gamma-irradiation on cyclooxygenase-2 (COX-2) expression and its enzymatic activity in PC-3 cells. Cell cycle redistribution, viability, and apoptosis were quantitated in control and irradiated cells with or without the COX-2 inhibitor NS-398.


METHODS
Western blot analysis was used to assess COX-2 protein expression. Prostaglandin (PGE(2)) was measured after addition of arachidonic acid (AA) using a Monoclonal Immunoassay Kit. Cell cycle and apoptosis were assessed using flow cytometry.


RESULTS
We observed a dose-dependent increase in COX-2 of 37.0%, 79.7%, and 97.5% following irradiation with 5, 10, and 15 Gy, respectively. The PGE(2) level of irradiated cells was higher than in controls (1512 +/- 157.5 vs. 973.7 +/- 54.2 rhog PGE(2)/mL; p < 0.005, n = 4) while cells irradiated in the presence of NS-398 had reduced PGE(2) levels (218.8 +/- 80.1 rhog PGE(2)/mL; p < 0.005; n = 4). We found no differences in cell cycle distribution or apoptosis between cells irradiated in the presence or absence of NS-398.


CONCLUSIONS
COX-2 protein is upregulated and enzymatically active after irradiation, resulting in elevated levels of PGE(2). This effect can be suppressed by NS-398, which has clinical implications for therapies combining COX-2 inhibitors with radiation therapy.
Steinauer
K K
KK
Department of Radiation Oncology, Stanford University School of Medicine, Stanford, CA 94305-5302, USA.
Gibbs
I
I
Ning
S
S
French
J N
JN
Armstrong
J
J
Knox
S J
SJ
D017209:Apoptosis / Q000502:physiology; D015415:Biomarkers; D015153:Blotting, Western; D002453:Cell Cycle / Q000502:physiology; D051546:Cyclooxygenase 2; D052246:Cyclooxygenase 2 Inhibitors; D016861:Cyclooxygenase Inhibitors / Q000494:pharmacology; D015232:Dinoprostone / Q000378:metabolism*; D004789:Enzyme Activation / Q000187:drug effects / Q000528:radiation effects; D005720:Gamma Rays; D006801:Humans; D007527:Isoenzymes / Q000378:metabolism / Q000528:radiation effects*; D008297:Male; D008565:Membrane Proteins; D009578:Nitrobenzenes / Q000494:pharmacology; D011451:Prostaglandin-Endoperoxide Synthases / Q000378:metabolism / Q000528:radiation effects*; D013449:Sulfonamides / Q000494:pharmacology; D013997:Time Factors; D014407:Tumor Cells, Cultured / Q000187:drug effects / Q000528:radiation effects; D015854:Up-Regulation
D015415:Biomarkers; D052246:Cyclooxygenase 2 Inhibitors; D016861:Cyclooxygenase Inhibitors; D007527:Isoenzymes; D008565:Membrane Proteins; D009578:Nitrobenzenes; D013449:Sulfonamides; C080955:N-(2-cyclohexyloxy-4-nitrophenyl)methanesulfonamide; D051546:Cyclooxygenase 2; C496540:PTGS2 protein, human; D011451:Prostaglandin-Endoperoxide Synthases; D015232:Dinoprostone