Effect of siRNA-mediated inhibition of c-myc on cell cycle in laryngeal carcinoma Hep-2 cells

Objective RNA interference(RNAi) was employed to inhibit the expression of c-myc and to evaluate the effects of c-myc as a target for gene therapy in laryngeal carcinoma Hep-2 cells.Methods Immunocytochemistry was used to determine the protein levels of c-myc.Hep-2 cells were transfected with 75 nM c-myc siRNA,c-myc protein and mRNA levels were detected using Western Blotting and RT-PCR.Hep-2 cells were treated with or without c-myc siRNA,5-Fu or combinations thereof for 48h.The cells were stained with PI and analyzed cell cycle by flow cytometry.Results Immunocytochemical analysis showed that c-myc was mainly expressed and localized in the cytoplasm in Hep-2 cells.The protein and mRNA levels of c-myc decreased after transfected with c-myc siRNA at different times.c-myc siRNA-transfected cells showed an increase in the percentage of cells in the G0/G1 phase and a decrease in the percentage of cells in the S phase.While combination with 5-Fu,the results were more prominence. Conclusions c-myc siRNA inhibits the expression of c-myc,induction G0/G1 arrest and increasing the sensitivity to 5-Fu.The result makes c-myc a target for the development of novel therapeutic strategies.