Objective     To evaluate the inhibitory effect of valdecoxib on the growth of the cancer cell lines and involvement of COX-2 in this inhibition.      Methods     Western blotting and immunocytochemistry were used to detect the expression of COX-2. MTT assay was used to determine inhibitory effect of the drugs on the cell growth. The content of PGE

2

in cell medium was determined with PGE

2

ELISA kit.      Results     ①Clone 26 cells expressed high levels of COX-2

wherea

s BGC-823，HGC-27 and SK-OV-3 cell had no COX-2 expression. ②Valdecoxib inhibited the growth of BGC-823

HGC-27

SK-OV-3 and clone 26 cells

with a IC

50

of 110.7

99.2

113.3

117.6 μmol/L

respectively. ③The inhibitory effect of these drugs on BGC-823 and clone 26 cell was in the descending order of valdecoxib

SC-560 and indomethacin. ④PGE

2

did not antagonize the effect of valdecoxib

SC-560 and indomethacin on BGC-823 and clone 26 cells. ⑤The inhibitory effect of valdecoxib and indomethacin on the growth of clone 26 cells was not compatible with that on PGE

2

.       Conclusion     The inhibitory effect of valdecoxib on cell growth is not related to its effect on COX-2.