The Effect Of HnRNP B₁ SiRNA On Human Telomerase Reverse Trancriptase On Lung Adenocarcinoma Cell Line A549

Objective Lung cancer is the leading cause of cancer-related mortality in both men and women. Many studies have demonstrated over expression of HnRNP B₁ in lung cancer. HnRNP B₁ binds the telomeric repeat sequence and promotes telomerase-mediated maintenace of telomere. It suggests that HnRNP B₁ maybe regulate telomerase activity, keep the length of telomere, and effect cell proliferation. hTERT is a core functional component of telomerase and has strong correlation with activity of telemorase in lung cancer. We try to explore melocular mechanism of HnRNP B₁ in development of lung cancer by observing activity of hTERT in lung adenocarcinoma cell line A549 after HnRNP B₁ interference.Methods The A549 cells transfected with HnRNP B₁ SiRNA were choosed for this experiment, and devided into 4 groups by different HnRNP B₁ SiRNA . The control groups were A549 cells transfected with pure plasmid and A549 cells without any transfection. The effect of HnRNP B₁ SiRNA on apopotosis of A549 cells was observed by flow cytometry. The level of HnRNP B₁ mRNA and hTERT mRNA in A549 cells was detected by RT-PCR . Immunocytochemistry was used to detect the protein expression of hTERT.Results (1) The effects of HnRNP B₁ SiRNA on apoptosis rate of lung adenocarcinoma cell line A549: HnRNP B₁ SiRNA decreased the proliferation of lung adenocarcinoma cell line A549, and increased its apoptosis rate . The apoptosis rate in experimental groups were respectively (19.2±1.25)%,(23.4±3.12)%,(24.0±2.28)% and (33.5±2.49) %, which was much higher than that of control group(P<0.05). The rate of cells of S period in experimental groups were respectively (27.0±2.97)%, (25.4±3.65)%, (24.2±4.12)% and (19.6±3.56)%, which was much lower than than of control group (P<0.05). (2)The effects of HnRNP B₁ SiRNA on expression of HnRNP B₁ mRNA: the expression of hnRNP B₁ mRNA was decreased in the experimental groups.The inhibition rate were 77.69%, 74.37%, 75.65% and 83.04%. (3) The effects of HnRNP B₁ SiRNA on expression of hTERT mRNA: According to RT-PCR, the hTERT mRNA was down-regulated in experimental groups. The inhibitory rate were respectively 88.67%, 90.67%, 91.33% and 86.67%. (4) The effects of HnRNP B₁ SiRNA on expression of hTERT protein: According to immunocytochemistry, HnRNP B₁SiRNA can decrease the expression of hTERT protein. The positive rate in HnRNP B₁ SiRNA A549 was much lower than that of control group ( p<0.05). (5) The expression of HnRNP B₁ mRNA was positive correlative with that of hTERT mRNA, while the expression of HnRNP B₁ mRNA and hTERT mRNA was negative correlative with the apoptosis rate.Conclusion (1) HnRNPB₁ SiRNA could specifically inhibit the expression of HnRNPB₁ gene. (2) HnRNPB₁ SiRNA can promote apoptosis and inhibit proliferation in A549 cells. (3) HnRNPBi SiRNA can reduce the expression of hTERT mRNA and protein in A549 cells. (4)HnRNP B₁ can effect cell proliferation and apoptosis of lung cancer by regulating the activity of hTERT.