Inhibitory effect of TRAIL combined with 5-fluorouracil on the proliferation of human colon carcinoma cells

Objective To observe the inhibitory effect of TNF-related apoptosis-inducing ligand( TRAIL) combined with 5-fluorouracil( 5-Fu) on the proliferation of human colon carcinoma cells and to investigate the mechanism. Methods The colon cancer cell line CT26 was digested into suspension( 3 × 104/ mL),inoculated into 96-well plates,and then they were divided into 4 groups: TRAIL group which was added 5,10,50,100,200 ng / mL TRAIL,5-Fu group which was added 5,10,15,20,25 μ g / mL 5-Fu,combined treatment group which was treated with 5,50,200 ng / mL TRAIL and 5-Fu 10 μ g / mL and the control group which was treated with 5,50,200 ng / mL TAIL. After culture for 24,48 and72 h,the inhibitory rate of CT26 cell proliferation was detected by MTT; the cell cycle and apoptosis rate were detected by flow cytometry; the expression of p21WAF1and p27 was detected by Western blotting; and the expression of apoptosis-related genes Bax and Bcl-2 was detected by immunohistochemistry. Results The single use of TRAIL and 5-Fu inhibited the proliferation,and the inhibition rate was negatively correlated with the 5-Fu concentration; the inhibition rate of combined treatment group was higher than that of the other 3 groups. Compared with the control group,the proportion of cells in G0/ G1phase was significantly increased,while the proportion was significantly decreased in S phase of the combined treatment group( all P 0. 05),and with the increase of TRAIL concentration,the proportion of cells in G0/ G1phase was increased( P 0. 05). Compared with the control group,the apoptosis rate of CT26 cells in the combined treatment group was increased with the increase of TRAIL concentration( P 0. 05). Compared with the control and 5-Fu groups,the expression levels of p21WAF1and p27 protein in the combined treatment group were significantly increased,and increased with the concentration of TRAIL( all P 0. 05). The expression level of Bax protein was higher in the combined treatment group than those of the control and 5-Fu groups,while the expession level of Bcl-2 was lower( all P 0. 05). Conclusion The combined use of TRAIL and 5-Fu can inhibit the apoptosis of colon cancer CT26 cells,and with a synergistic antitumor effect,whose mechanism may be related to the up-regulation of p21WAF1,p27 and Bax protein expression,down-regulation of Bcl-2 protein expression.