Objective      To determine the effect of valdecoxib on the growth inhibition and radiosensitivity enhancement of nasopharyngeal carcinoma cell line CNE-2.       Methods      CNE-2 cells were divided into 6 groups

according to different treatment

such as control group (DMSO)

cisplatin group (50 μmol/L)

valdecoxib group (50 μmol/L)

valdecoxib+cisplatin Group (both 50 μmol/L)

wortmannin group (1 μmol/L) and valdecoxib+wortmannin group (50 μmol/L valdecoxib+1 μmol/L wortmannin). MTT assay was employed to test the cell growth. Hoechst method was used to test apoptosis index and flow cytometry was applied to measure cell cycle. Tablet colony formation test was used to detect radiation sensitizing effect. Western blot analysis was used to detect COX-2 protein

Akt and p-Akt (Ser473)

and NAG-1 protein.       Results      Valdecoxib of 50 μmol/L resulted in increased proliferation inhibition  and apoptotic index

elevated radiosensitization

increased cells at G

0

/G

1

phase and S phase

reduced protein levels of COX-2

p-Akt

p-Akt/Akt and raised level of NAG-1 (P0.05 vs control group). Combination with 50 μmol/L cisplatin or 1 μmol/L of wortmannin (PI3K inhibitor) enhanced the effect of valdecoxib on cell cycle

proliferation inhibition and radiosensitization (P0.05) as well as in reducing cells at G

2

/M phase. Cisplatin of 50 μmol/L had no effect on COX-2

Akt

p-Akt (Ser473) and NAG-1 protein levels

while combination with cisplatin did not change the effect of valdecoxib on the above proteins (P0.05). Wortmannin of 1 μmol/L reduced p-Akt and p-Akt/Akt

and elevated NAG-1 level

and combination with valdecoxib enhanced the effect of valdecoxib on the above proteins (P0.05).       Conclusion       Valdecoxib inhibits the proliferation of CNE-2 cells

promotes apoptosis and radiosensitization in possible mechanism of reducing COX-2 and PI3K /Akt/NAG-1.