Celecoxib induces dose dependent growth inhibition in nasopharyngeal carcinoma cell lines independent of cyclooxygenase-2 expression

Celecoxib is a cyclooxygenase-2 (COX-2) selective non-steroidal anti-inflammatory drug (NSAID) which has been shown to be capable of inhibiting the growth of various cancer cell lines. However, studies of its effect on the growth of nasopharyngeal carcinoma (NPC) cells are scarce. In this study, we investigated the effect of celecoxib on cell growth using three NPC cell lines: HK-1, Hone-1 and CNE-2. Our results showed that while all 3 cell lines expressed the COX-2 mRNA as determined by reverse transcription-polymerise chain reaction (RT-PCR), western blot analysis showed that only HK-1 expressed the COX-2 protein. Using MTT assay, celecoxib was found to inhibit growth in all 3 cell lines in a dose dependent manner. The IC50 of celecoxib were 41.04 ± 1.22, 49.68 ± 1.12 and 51.74 ± 3.89 μM for CNE-2, Hone-1 and HK-1 cells, respectively. This growth inhibitory effect was found to be independent of the cell line's COX-2 protein expression level of the cells lines. In HK-1 cells, the expression of the cell cycle regulatory protein, cyclin D1, was down regulated by incubation with 80 μM celecoxib for 24 hrs.