The Effects Of Nimesulide On Proliferation Of Human Breast Cancer Cell MDA-MB-231 And Its Mechanisms

Objective To study the detail mechanism of nimesulide's cytostatic effects on human breast cancer cell line MDA-MB-231.Methods Exponential phase human breast cancer cell line MDA-MB-231 was treated by nimesulide in various concentrations(50,100,200,400μmol/L) in vitro,the inhibitory rations of the cells were measured by a tetrazolium-based colorimetric assay (MTT) in different concentrations and time;apoptosis and distribution of cell cycles were examined with flow cytometry;the expression of Bcl-2,Bax and COX-2 in tumor cells was detected with Power visionTM immunohisto-chemical(ICC) method;the expression of COX-2 mRNA was determined by reverse transcriplase polymerase chain reaction(RT-PCR) to study the mechanism of apoptosis induced by nimesulide;PGE2 was examined in the supernatant fluid using ELISA.Results MTT assay show that nimesulide could inhibit the growth of the human breast cancer cell line MDA-MB-231,and the inhibitory effect was dose and time-dependent manner(P<0.05).the inhibition rate was 51.3% when the dentisy was 200μmol/L for 48h.There was an apoptotic peak in MDA-MB-231 cells after incubating with nimesulide detected by flow cytometry.Quantitative analysis result from DNA bargragh was that cell apoptotic ratio of 50,100,200,400μmol/L density was6.94±1.02%,12.10±1.51 %,30.27±1.98%, 38.27±3.03 %,the difference was significant compared to the control group. the cells in G1/G0 stage multed as the density of nimesulide increased,cells in S and G2 stage descended gradually.the expressions of COX-2 and bcl-2 were downregulated,there were many eumorphism in cells in control group,however the expression of bax was upregulated significantly as the density of nimesulide increased.many eumorphism could be in cell membrane and emdochylema rather than control group.the expression of COX-2 mRNA was determined by reverse transcriplase polymerase chain reaction(RT-PCR).expression of COX-2 mRNA was downregulated through ladder strap as the increasing of nimesulide concentration.Conclusion It suggests that nimesulide has the capabilities of inhibiting proliferation and inducing apoptpsis in MDA-MB-231 cells in vitro,the effects is in a dose and time dependt-manner,its cytostatic mechanism may be associated with reducing the expression of COX-2 and bcl-2,dwonregulating the expression of bax.