title: Potentiation of tumor response to radiation or chemoradiation by selective cyclooxygenase-2 enzyme inhibitors.
abstract: Cyclooxygenase-2 (COX-2) is an enzyme expressed primarily in pathologic states, such as inflammatory disorders and cancer, where it mediates prostaglandin production. Its overexpression is associated with more aggressive biologic tumor behavior and adverse patient outcome. Increasing evidence shows that agents that selectively inhibit COX-2 enhance tumor response to radiation or chemotherapeutic agents. This article gives an overview of some of this evidence. In addition, we describe new results showing that celecoxib, a selective COX-2 inhibitor, enhanced response of A431 human tumor xenografts in nude mice to radiation by an enhancement factor (EF) of 1.43 and to the chemotherapeutic agent docetaxel by an EF of 2.07. Celecoxib also enhanced tumor response when added to the combined docetaxel plus radiation treatment (EF = 2.13). Further experiments showed that selective COX-2 inhibitors enhanced tumor cell sensitivity to ionizing radiation, involving inhibition of cellular repair from radiation damage and cell cycle redistribution as mechanisms for some cell types. The results show that selective COX-2 inhibitors have the potential to improve tumor radiotherapy or radiochemotherapy, and this therapeutic strategy is currently under clinical testing.
authors.affiliation: Department of Experimental Radiation Oncology, The University of Texas M. D. Anderson Cancer Center, 1515 Holcombe Boulevard, Houston, TX 77030-4009, USA.
authors.forename: Eiko
authors.initials: E
authors.lastname: Nakata
authors.forename: Kathryn A
authors.initials: KA
authors.lastname: Mason
authors.forename: Nancy
authors.initials: N
authors.lastname: Hunter
authors.forename: Amir
authors.initials: A
authors.lastname: Husain
authors.forename: Uma
authors.initials: U
authors.lastname: Raju
authors.forename: Zhongxing
authors.initials: Z
authors.lastname: Liao
authors.forename: Kian K
authors.initials: KK
authors.lastname: Ang
authors.forename: Luka
authors.initials: L
authors.lastname: Milas
mesh_terms: D000818:Animals; D000068579:Celecoxib; D003131:Combined Modality Therapy; D051546:Cyclooxygenase 2; D052246:Cyclooxygenase 2 Inhibitors; D016861:Cyclooxygenase Inhibitors / Q000627:therapeutic use*; D004347:Drug Interactions; D006801:Humans; D007527:Isoenzymes / Q000037:antagonists & inhibitors* / Q000378:metabolism; D008565:Membrane Proteins; D051379:Mice; D008809:Mice, Inbred C3H; D008819:Mice, Nude; D009363:Neoplasm Proteins / Q000037:antagonists & inhibitors* / Q000378:metabolism; D009369:Neoplasms / Q000188:drug therapy* / Q000532:radiotherapy*; D011451:Prostaglandin-Endoperoxide Synthases / Q000378:metabolism; D011720:Pyrazoles / Q000627:therapeutic use*; D011836:Radiation Tolerance; D011838:Radiation-Sensitizing Agents / Q000627:therapeutic use*; D013449:Sulfonamides / Q000627:therapeutic use*; D000096926:Benzenesulfonamides
chemical_list: D000068579:Celecoxib; D051546:Cyclooxygenase 2; D052246:Cyclooxygenase 2 Inhibitors; D016861:Cyclooxygenase Inhibitors; D007527:Isoenzymes; D008565:Membrane Proteins; D009363:Neoplasm Proteins; D011451:Prostaglandin-Endoperoxide Synthases; D011720:Pyrazoles; D011838:Radiation-Sensitizing Agents; D013449:Sulfonamides; C119130:4-(5-(4-chlorophenyl)-3-(trifluoromethyl)-1H-pyrazol-1-yl)benzenesulfonamide; D000096926:Benzenesulfonamides; C496540:PTGS2 protein, human