Effect of all-trans retinoic acid combined with temozolomide on U251 glioma cells

Objective To investigate the effect of combined treatment of all-trans retinoic acid (ATRA) and temozolomide (TMZ) on U251 glioma cells.Methods U251 glioma cells were treated with ATRA,TMZ,or ATRA combined with TMZ.The growth inhibition rate of each group was tested by using methyl thiazol tetrazolium (MTF) assay,and the apoptosis rate was analyzed by using flow cytometry.The protein expression of bax/bcl-2,Caspase-3,Caspase-8 and Caspase-9 was detected by using Western blotting.Results The growth inhibition rate of U251 glioma cells in ATRA group,TMZ group and combination group was (43.64 ± 5.09) ％,(35.77 ± 5.39) ％ and (56.84 ± 4.18) ％,and the apoptosis rate was (24.93.± 4.58) ％,(21.36 ± 3.76) ％ and (41.66 ± 5.02) ％,respectively.In ATRA group,TMZ group and combination group,the expression of bcl-2 was lower,but that of bax,Caspase-3,Caspase-8 and Caspase-9 was higher than in control group.These changes were more obvious in the combination group.Conclusion Both ATRA and TMZ can inhibit the growth of U251 cells and promote apoptosis,and exert the synergetic effect,which may be related to the down-regulation of the expression of bcl-2 and upregulation of bax/bcl-2,Caspase-3,Caspase-8 and Caspase-9 in U251 cells. Key words: All-trans retinoic acid ;  Temozolomide;  Glioma;  Apoptosis