Downregulation of hnRNP K by RNAi inhibits growth of human lung carcinoma cells

Lung cancer is one of the most common malignancies worldwide, but its pathogenesis remains unknown. The current study examined the effects of heterogeneous nuclear ribonucleoprotein K (hnRNP K)-targeted small interfering RNA (siRNA) on the growth and apoptosis of lung cancer cells in vitro. The expression of hnRNP K was studied by the SP method of immunohistochemistry in lung tissue samples of 70 cases of lung cancer. hnRNP K siRNA were transfected into human lung cancer cell line, A549, using Lipofectamine 2000. Cells transfected with siRNAn and untreated served as controls. The inhibitory effect of siRNA on the expression of hnRNP K mRNA and protein was detected by reverse transcription polymerase chain reaction and western blot analysis. The change in cell cycling and cell apoptosis of siRNA-treated cells was detected by flow cytometry. The rates of positive hnRNP K expression in lung tumors of diameters ≤3, 3–5 and ≥5 cm, were 38.5, 95.2 and 91.7%, respectively. A significant difference was identified between lung tumors with diameters of ≤3 and ≥3 cm (P<0.01). The expression of hnRNP K mRNA was significantly inhibited in siRNA-transfected cells compared with that in control cells (P<0.05). Notably, hnRNP K protein decreased in hnRNP K siRNA-transfected cells, but exhibited no effect on the control groups. siRNA targeting human hnRNP K effectively inhibited the growth of lung cancer cell line, A549, and the distribution of the cell cycle. The apoptosis rate was 4.79% and the number of cells increased in the G0/G1 phase from 37.21 to 85.60% and decreased in the S and G2/M phases from 47.71 to 13.50% and 14.00 to 0.32%, respectively, following 24 h of transfection. hnRNP K siRNA promotes A549 apoptosis and the apoptosis rate was 4.79% (P<0.01). Therefore, hnRNP K siRNA may inhibit the proliferation of A549 cells. In addition, hnRNP K promotes the growth of lung cancer cells and, therefore, hnRNP K siRNA may inhibit the growth and increase the apoptosis of lung cancer cells.