Inhibitory effect of siRNA-mediated MSK1-silencing on the proliferation of CNE2 cells and its mechanisms / 医学研究生学报

ABSTRACT

Objective Abnormal activation of mitogen-and stress-activated kinase (MSK1) plays an important role in the development of various cancers.This study was to explore the effect of small interfering RNA (siRNA)-mediated MSK1-silencing on the proliferation of human nasopharyngeal carcinoma (NPC) cells and its underlying mechanism.Methods The siRNA vector targeting MSK1 was constructed and transfected into CNE2 cells, and the NPC cell line stably expressing MSK1 was established.Then the cells were divided into a blank control (without transfection of the plasmid), a negative control (with stable transfection of the negative control plasmid), and an experimental group (with stable transfection of the positive recombinant plasmid).The expressions of MSK1 mRNA and protein were detected by real-time quantitative PCR and Western blot, respectively, the proliferation of the cells determined by CCK-8 and colony formation assays, the cell cycles analyzed by flow cytometry, the level of histone H3 phosphorylation at Ser10 examined by Western blot, and The transcriptional activity and expression of the c-jun protein measured by dual-luciferase reporter gene assay and Western blot.Results Compared with the blank control, the inhibition rates of cell proliferation at 48, 72 and 96 hours were significantly reduced in the experimental group (P<0.05), and so were the colony formation ability of the cells (P<0.01) and the expression and transcriptional activity of the c-jun protein (P<0.05).In comparison with the negative control, the experimental group showed significant decreases in the rate of cell growth after 24 hours, the inhibition rates of cell proliferation at 48, 72 and 96 hours (P<0.05), the number of formed colonies ([221.00±20.08] vs [99.67±15.57] / 300 cells, P<0.01), the proportion of S-phase cells (P<0.01), and the expression of the c-jun protein in the CNE2 cells ([100.00±0.00] vs [48.77±10.71] %, P<0.05), but a remarkable increase in the percentage of G0/G1-phase cells (P<0.01).Furthermore, histone H3 phosphorylation at Ser10 was markedly reduced (P<0.01) but no significant change was observed in the expression of the total c-jun protein in the experimental group.Conclusion Knockdown of MSK1 using siRNA can significantly inhibit the growth and proliferation of CNE2 cells, which may be closely related to the decreased phosphorylation of histone H3 and subsequently down-regulated transcriptional activity of c-jun.