J Korean Soc Ther Radiol Oncol.  2003 Sep;21(3):216-221.

The Enhancement of Radiosensitivity by Celecoxib, Selective Cyclooxygenase-2 Inhibitor, on Human Cancer Cells Expressing Differential Levels of Cyclooxygenase-2

• Pyo H
• Shin YK
• Kim HS
• Seong J
• Suh CO
• Kim GE

Abstract

PURPOSE: To investigate the modulation of radiosensitivity by celecoxib, a selective cyclooxygenase-2 (COX-2) inhibitor, on cancer cells over- and under-expressing COX-2.
MATERIALS AND METHODS
A clonogenic radiation survival analysis was performed on A549 human lung and MCF-7 human breast cancer cell lines incubated in both 1 and 10% fetal bovine serum (FBS) containing media. The apoptosis in both cell lines was measured after treatment with radiation and/or celecoxib.
RESULTS
Celecoxib enhanced the radiation sensitivity of the A549 cells in the medium containing the 10% FBS, with radiation enhancement ratios of 1.58 and 1.81 respectively, at surviving fractions of 0.1, with 30 microM and 50 microM celecoxib. This enhanced radiosensitivity disappeared in the medium containing the 1% FBS. Celecoxib did not change the radiation sensitivity of the MCF-7 cells in either media. The induction of apoptosis by celecoxib and radiation was not synergistic in either cell line.
CONCLUSION
Celecoxib, a selective COX-2 inhibitor, preferentially enhanced the effect of radiation on COX-2 over-expressing cancer cells compared to the cells with a low expression, and this effect disappeared on incubation of the cells during drug treatment in the medium with suboptimal serum concentration. Apoptosis did not appear to be the underlying mechanism of this radiation enhancement effect due to celecoxib on the A549 cells. These findings suggest radiosensitization by a selective COX-2 inhibitor is COX-2 dependent.

Keyword

Cyclooxygenase-2; COX-2; Radiation; A549; MCF-7

MeSH Terms

Apoptosis
Breast Neoplasms
Cell Line
Cyclooxygenase 2*
Humans*
Lung
MCF-7 Cells
Radiation Tolerance*
Celecoxib
Cyclooxygenase 2