Objective:To investigate the effect of NS398

cyclooxygenase-2（COX-2）-inhibitor

on the antergy of lysophosphatidic acid （LPA）for the inhibiting effect of cisplatin（DDP）in the proliferation of huanman ovarian cancer

and to analyze its possible mechanism. Methods:Human ovarian cancer cell line（3AO）were cultured in vitro.The effect of NS398 on the antergy of LPA for the inhibiting effect of DDP in the proliferation of 3AO cells were measured by MTT.Cell cycle of 3AO were analysed by flow cytometry（FCM）.The effect of LPA alone or in combination with NS398 on the expression of COX-2 of 3AO cells were measured with RT-PCR.Results:LPA showed antergy on the inhibiting effect of DDP in the proliferation of 3AO cells

and decrease the proportion of cells in the G

0

/G

1

phase of the cell cycle.Whereas

combined with NS398 in culture

the proliferation of were significantly inhibited

and the the proportion of cells in the G

0

/G

1

phase of the cell cycle was raised.RT-PCR results revealed that 40μmol/L LPA could promote the expression of COX-2 in 3AO cells

and in combination with NS398

the expression of COX-2 was decreased.Conclusion:The reverse effect of NS398 for the antergy of LPA on the inhibiting effect of DDP in the proliferation of 3AO cells may be completed by inhibiting the expression of COX-2 in these cells.