Blockage of PKM2 expression by gene silencing enhances the radiosensitivity of human lung cancer A549 cells / 中华放射医学与防护杂志

ABSTRACT

Objective To explore the role of pyruvate kinase M2 (PKM2) siRNA in the radiosensitivity of human lung cancer A549 cells.Methods PKM2 siRNA was synthesized according to the coding sequence of PKM2 mRNA and then was transferred into A549 cells with lipofectamine.The expressions of PKM2 gene and protein was detected by RT-PCR and Western blot,respectively.The experiments were divided into PKM2 siRNA interference group,siRNA negative control group,and blank control group.The cells of each group were exposure to 6 MV X-rays in different dose.Radiosensitivity was evaluated by colony formation assay.Flow cytometry was applied to analyze cell cycle distribution and apoptosis.Data are representative of three independent experiments.Results Ccompared with blank control cells,the expressions of PKM2 gene and protein in the PKM2 siRNA transferred A549 cell was efficiently diminished (t =20.91,47.00,P ＜0.01) with inhibition rates of (70.27 ± 1.38)％ and (70.42 ± 1.18) ％,respectively.Compared with control,PKM2 siRNA transfection significantly decreased the D0,Dq,N and SF2 values (t =43.82,28.44,15.60,29.63,P ＜ 0.01) and hence yield a sensitization enhancement ratio (SER) of 1.27.In addition,the percentage of G2/M phase cells in the siRNA group and irradiated group were both significantly higher than that of the blank control group (t =8.35,27.87,P ＜ 0.01).The combined treatments of PKM2 siRNA interference and irradiation arrested more cells in the G2/M phase compared to either treatment alone.The apoptosis rate of siRNA group was not dramatically different from that of blank control group.The apoptosis rate of irradiation group was higher than that of blank control group (t =23.99,P ＜ 0.01),and the combined treatments of siRNA and irradiation enhanced the apoptotic rate compared to either treatment alone (t=9.42,65.21,P ＜ 0.01).Conclusions Specific blockage of PKM2 expression by gene silencing could enhance the sensitivity of human lung cancer A549 cells to radiotherapy in vitro,which may due to the cell cycle arrest and apoptosis induction after irradiation.