Apoptosis induced by celecoxib combinated with cisplatin in human osteosarcoma cell line MG-63 via down-regulation of PI3K/Akt

Abstract

Objective To identify the anti-proliferation of celecoxib, a selective cyclooxygenase-2 (COX-2) inhibitor, and the combination of celecoxib and cisplatin in MG-63 cells, and to explore the poten-tial molecular mechanisms involved. Methods MG-63 cells were treated with the combination of celecoxib (50 μmol/L or 100 μmol/L) and/or cisplatin (10 μg/ml) for 48 h in serum-supplemented medium. Cell viabil-ity was measured by MTT assay; apoptosis was determined by electronmicroscope and flow cytometry (FCM); gene transcription and protein expression were detected by RT-PCR and/or Western blot analysis. Results MG-63 cells were significantly inhibited by celecoxib at G1 phase. The cisplatin-induced apoptosis was 5.93%, and potentiated to 6.66% and 37.15% while combining with celecoxib (50 μmol/L and 100 μmol/L) respectively. There was significant synergetic effect between celecoxib and cisplatin. The protein expression of COX-2 did not occur in cells treated with celecoxib. PI3K/Akt, survivin, Bcl-2 were significantly down-regulated in cells treated with the combination of celecoxib and cisplatin. Moreover, the decreased expres-sions of pro-caspase-9, pro-caspase-3 and cleaved PARP-1 were detected by Western blot analysis. And pAkt (Thr308), survivin and Bcl-2 levels down-regulated in cells treating with Wortmannin for 48 h, a spe-cific PI3K inhibitor. Conclusion Celecoxib exerts its anti-tumor activities through COX-2 independent mechanisms, which may be PI3K/Akt-dependent, and survivin and Bcl-2-related. PI3K may be at the center of the celecoxib effects, which play an essential role in the regulation of survivin and Bcl-2. Key words: Osteosarcoma; Cisplatin; Apoptosis; Caspases