Synergistic inhibitory effect of nimesulide in combination with 5-fluorouracil on gastric cancer cells and its possible mechanisms / 中华消化杂志

ABSTRACT

Objective To investigate the inhibitory effects of combined treatment of nimesulide, a selective cyclooxygenase-2 inhibitor, with 5-fluorouracil (5-FU) on gastric cancer cell lines and its pos-sible mechanisms. Methods The human gastric cancer cell lines MKN45 and MKN28 were used in the study. After 48 hours treatment with nimesulide or 5-FU alone or in combination, the cells growth was determined by MTT assay. Flow cytometry and FITC-Annexin-V/PI kit were used to determine the effect of drugs on the cell cycle and the apoptosis of gastric cancer cells. The expression of COX-2 mRNA was detected by RT-PCR. The expressions of apoptosis-associated protein Bax and Bcl-2 were detected by Western blotting. Results Different level of COX-2 mRNA expression was observed in MKN45 and MKN28 cell lines. Treatment of the two cell lines with nimesulide in combination with 5-FU can significantly reduce the expression of COX-2 mRNA. Nimesulide could inhibit the growth and induce apoptosis of gastric cells. Combined treatment of nimesulide with 5-FU resulted in a synergistic effect of inhibiting growth and inducing apoptosis. The synergistic inhibiting effect on cell growth was irrespective of treatment sequence, but the highest cytotoxity was obtained when the cell lines were treated with two drugs simultaneously. Treatment with 5-FU enhanced expression of the pro-apoptotic gene Bax, while nimesulide reduced expression of the anti-apoptotic gene Bcl-2, resulting in a significantly higher ratio of Bax-to-Bcl-2. Conclusions The combined treatment of nimesulide with 5-FU results in synergistic inhibiting effect on growth of gastric cancer cell lines, and inducing apoptosis by enhanced Bax-to-Bcl-2 ratio and suppression of COX-2 mRNA expression may be the mechanisms.