Effects of estrogen receptor β gene silencing mediated by small interference RNA on apoptosis of human lung cancer LTEP-a2 cells

Objective To investigate the effect of estrogen receptor β (ERβ) gene silencing mediated by small interference RNA (siRNA) on apoptosis of human lung cancer LTEP-a2 cells overexpressing ERβ and the sensitivity to 17β-estradiol. Methods siRNA was designed and synthesized as expression vector and transfected into human lung cancer LTEP-a2 cells. After 48 h, the collected cells were randomly divided into the negative control group, the blank control group and the transfected group. Transcription-polymerase chain reaction (RT-PCR) was used to detect ERβ mRNA, and Western blotting was used to detect the expression of ERβ protein. Cellular growth was tested by methylthiazoltetrazolium colorimetry (MTT) assay and the median inhibitory rate (IC50) of each group was calculated. The cell apoptosis rate after treatment by 17β-estradiol was detected by flow cytometry. Results The expression intensities of ERβ mRNA in negative control, blank contro1 and siRNA group were 0.32±0.06, 0.28±0.05 and 0.05±0.02 respectively. The expression of ERβ mRNA was decreased significantly in siRNA group as compared with negative control group (P=0.032) and blank control group (P=0.015). The expression intensities of ERβ protein in negative control, blank contro1 group and siRNA group were 0.18±0.04, 0.28±0.03 and 0.06±0.01, respectively. The expression of ERβ protein was decreased significantly in siRNA group as compared with negative control group (P=0.038) and blank control group(P=0.000). After intervention with different concentrations of 17β-estradiol, the survival rate was decreased significantly in transfected group as compared with negative control group and blank control group ; The value of half maximal inhibitory concentration (IC50) in negative control , blank contro1 and siRNA group were (28.34±4.32)%, (27.66±3.04)% and (8.34±1.22)%, respectively. the growth of the lung cancer cell LTEP-a2 was significantly inhibited in siRNA group as compared with negative control group and blank control group ; the apoptosis rate in the transfected group was significantly higher than that in the negative control group and blank control group [(35.68±1.58)%, (3.55±0.33)% and (2.34±0.58)% respectively]. Conclusion ERβ gene silencing mediated by siRNA might inhibit growth and promote the apoptosis of non-small lung cancer with estrogen intervention. ERβ could play a significant role in screening female sex hormone-dependent non-small lung cancer. Key words: Lung cancer; Sex hormone; Small interference RNA; Estrogen receptor β gene; Apoptosis