RESUMO
Objective:The study was to investigate the effects of epidermal growth factor receptor (EGFR) antibody (cetuximab,C225) combined with cyclooxygenase 2(COX-2)inhibitor (nimesulide) on the proliferation and apoptosis of colon cancer HT-29 cells, and explore the potential molecular mechanism. Methods:C225 and nimesulide alone or in combination were incubated with HT-29 cells. MTT assay was used to measure the cell proliferation. AO/EB staining and flow cytometry were used to measure the cell apoptosis. RT-PCR was used to detect the COX-2 and non steroidal anti-inflammatory drug-activated gene (NAG-1) mRNA expression levels. The expression of Akt and phosphor-Akt protein was examined by Western blotting. Results:The inhibitory effect of nimesulide combined with C225 was significantly stronger than that of nimesulide alone [(72.8±2.3)% vs (51.8±1.8)% , P<0.05]at 48 h. Typical changes of apoptosis in HT-29 cells were observed in nimesulide combined with C225 treatment group. The apoptosis rate of combined group was significantly higher than that of single nimesulide group [(57.67±0.86)% vs(33.27±1.47)%]and single C225 group [(6.27±0.55)%,P<0.05]. C225 down-regulated the expression of COX-2 mRNA. The expression of NAG-1 mRNA was up-regulated in all treatment groups and the expression of phosphor-Akt was significantly down-regulated in combined treatment group than single nimesulide or C225 group. Conclusion:Nimesulide combined with C225 has obvious synergistic effects in inducing apoptosis. The potential mechanisms may be that EGFR signaling pathway is involved in the regulation of cycloxygenase-2 expression in HT-29 cells and finally influence the proliferation and apoptosis of HT-29 cells through the up-regulation of NAG-1 and down-regulation of phosphor-Akt expression.