Abstract:

Objective      To investigate the sensitivity of Kasumi-1 cells to sodium valproate(VPA), a histone acetylation enzyme inhibitor(HDACI), after silence of the AML1/ETO gene. Methods       The plasmid pGCsiRNAAML1/ETO was transfected into Kasumi-1 cells by liposomes. Expressions of AML1/ETO and Bcl-2 mRNA were assayed by real time PCR(RTPCR). The effect of VPA on proliferation of Kasumi-1 cells was assessed by MTT. The cell cycle was assessed by flow cytometry. The morphology of apoptosis after Hochest33258 staining was observed under a fluorescence microscope. Results      After transfection with pGCsiRNAAML1/ETO, expression of AML1/ETO mRNA in Kasumi1 cells was reduced by 53.7% compared with the controls(P<0.05), while expression of Bcl-2 mRNA was reduced by 54.5%(P<0.05). The inhibitory effect of VPA on proliferation of Kasumi-1 cells was concentration-and time-dependent, and inhibitory rates in the transfected group were higher than those in the control group 24 h and 48 h after transfection, with different VPA concentrations. Rates of cells in the G0/G1 phase in the control group and the transfected group were (42.07±5.23)% and (62.6±5.87)%, respectively(P<0.01). After the treatment with VPA(2mmol/L)for 48h, the rates increased to(69.2±7.02)% and (78.92±6.23)%, respectively(P<0.01). Aftertransfection, cells presented karyopyknosis, nuclear margination and apoptotic bodies. Conclusion      siRNA specifically targeting the AML1/ETO gene can remarkably down-regulate expression of the AML1/ETO gene, and enhances the sensitivity of Kasumi-1 cells to HDACI.

Key words: RNA interference; AML1/ETO fusion gene; Kasumi-1 cells; Sodium valproate