In vitro interaction of cyclooxygenase-2 inhibitors with radiation in nasopharyngeal carcinoma cell line: Dependence on sequence of administration

Abstract

In nasopharyngeal carcinoma (NPC), COX-2 inhibitors have been reported to exhibit dose-dependent growth inhibition of these cancer cells, but their interaction with radiation has not yet been studied. Here, we examined the effects of selective COX-2 inhibitors SC-236 and NS-398 on the radiosensitivity of NPC cells. When incubated with COX-2 inhibitors prior to irradiation, increased radiation cell kill was documented. However, when the sequence of COX-2 administration was reversed, we observed radioprotection instead. Our findings hereby confirmed the enhancement effect of COX-2 inhibitors on radiation cell kill in vitro, but this effect is critically dependent on their sequence of administration. Key words: Cyclooxygenase-2, inhibitors, nasopharyngeal carcinoma, radiosen-sitization, radioprotection