Effects of siRNA against c-myc on cell proliferation,cell cycle,and expression of c-myc of HL-60 cells cultured in vitro

Aim:To study the effects of small interfering RNA (siRNA) targeting c-myc gene on the proliferation of HL-60 cells and endogenous c-myc gene expression and its possible role in gene therapy for leukemia by siRNA.Methods:HL-60 cells were allocated into transfected,negative control,and blank control.The cells cultured in vitro were detected after 24～96 h. The cell proliferation was investigated by MTT. The cell cycle was analyzed by flow cytometry. The expressions of the c-myc mRNA was assessed by RT-PCR and the protein was observed by immuno-cytochemistry.Results:Compared with the other two controls,the proliferation of transfected cell was significantly repressed(P0.05). This inhibitory effect was significant at 48,72 h after transfection(P0.05). Transfected HL-60 cells in S phase decreased from (56.1±4.7)% to (29.2±3.5)% and the cells arrested in G0/G1 phase increased from (36.8±3.3)% to (53.6±4.3)% (P0.05). After HL-60 cells being treated with siRNA,the expression of c-myc gene mRNA reached its bottom at 24 h (P0.05) and return to normal level at 96 h(P0.05). When the HL-60 cells were treated with siRNA,the score of C-myc protein expression in positive cells was significantly lower compared with their corresponding blank control group and negative control group (P0.05).Conclusion:The siRNA targeting c-myc gene could inhibit the proliferation of HL-60 cells and endogenous c-myc gene expression significantly and may be a new therapeutic target bite in the treatment of leukemia.