Effects of small interfering RNA targeting polo-like kinase-1 on the proliferation of human glioma cells in vitro

Objective To investigate the regulatory role of polo-like kinase-1 (PLK1) gene in the proliferation of human glioma cells. Methods Five small interfering RNAs (siRNAs) targeting PLK1 gene were designed and synthesized according to PLK1 mRNA sequence. After transfection of human glioma TJ905 cells with the siRNAs, real-time RT-PCR and Western blotting were performed to examine the changes in PLK1 gene expression in the cells. The growth of the transfected cells was evaluated by MTT assay and proliferating cell nuclear antigen (PCNA) protein expression determined using Western blotting. Telomeric repeat amplification protocol-enzyme-linked immunosorbent assay (TRAP-ELISA) was used to detect the changes in telomerase activity of the transfected cells. Results All the five siRNAs were capable of suppressing PLK1 mRNA expression in TJ905 cells, among which the P4 siRNA showed the strongest effect by reducing the PLK1 mRNA level by 93% 48 h after transfection at the concentration of 100 nmol/L. Compared with the oligofecamine control group cells the protein expression of PLK1 in TJ905 cancer cells transfected with P4 siRNA was also siguifieantly down-regulated. Transfection with P4 siRNA resulted in significant dose-dependent inhibitory effects on the proliferation and PCNA protein expression of TJ905 cells as compared to oligofecamine control group. The results of TRAP-ELISA showed obvious time- and dose-dependent inhibition of telomerase activity in the transfected cells as compared to oligofecamine control group. Conclusion PKL1 gene plays an important regulatory role in the proliferation of human glioma cells, and RNA interference of PLK1 gene can inhibit the cell proliferation possibly by suppressing the telomerase activity. Key words: Glioma;  Polo-like kinase-1;  RNA interference;  Small interfering RNA; Telomerase