In:
Clinical Cancer Research, American Association for Cancer Research (AACR), Vol. 12, No. 16 ( 2006-08-15), p. 4989-4999
Abstract:
Purpose: To characterize the radiation-enhancing effects and underlying mechanisms of combined treatment with celecoxib, a cyclooxygenase-2 selective inhibitor, and gefitinib, an epidermal growth factor receptor (EGFR) tyrosine kinase inhibitor, in human lung cancer cells. Experimental Design: Clonogenic cytotoxicity assays and clonogenic radiation survival assays after treatments with celecoxib and gefitinib with or without radiation were done on three human lung cancer cell lines. Synergisms after combined treatment with celecoxib, gefitinib, and radiation were investigated using isobologram and statistical analyses according to an independent action model. Alterations in apoptosis and cell cycle were measured to identify the mechanisms underlying the cell killing or radiation-enhancing effects of celecoxib and gefitinib combination treatment. Western blots for phosphorylated EGFR, EGFR, cyclooxygenase-2, and G2 checkpoint molecules were conducted after treatment with celecoxib and/or gefitinib with or without radiation. Results: Combination celecoxib, gefitinib, and radiation treatments were shown to be synergistic in causing clonogenic cell deaths in all cell lines tested, but the nature of synergism was cell type specific. The combined drug treatments induced apoptosis in an additive manner in A549 cells and in a synergistic manner in NCI-H460 and VMRC-LCD cells. Celecoxib or gefitinib attenuated radiation-induced G2-M arrest, and combined drug treatment additively attenuated radiation-induced G2-M arrest in all cell lines. Radiation-induced checkpoint kinase (Chk) 1 and Chk2 phosphorylation were inhibited by celecoxib and gefitinib treatment, respectively. Conclusions: Combined celecoxib and gefitinib treatments were shown to synergistically enhance the effect of radiation on lung cancer cells. The mechanisms underlying these synergistic effects seem to involve the synergistic enhancement of apoptosis and cooperative attenuation of radiation-induced G2-M arrest, possibly via Chk1 and Chk2 inhibition, by the combined drug treatments.
Type of Medium:
Online Resource
ISSN:
1078-0432
,
1557-3265
DOI:
10.1158/1078-0432.CCR-05-2259
Language:
English
Publisher:
American Association for Cancer Research (AACR)
Publication Date:
2006
detail.hit.zdb_id:
1225457-5
detail.hit.zdb_id:
2036787-9
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