Knockdown of Raf kinase inhibitor protein promotes the proliferation of LX-2 human hepatic stellate cells

Objective To investigate the role of Raf kinase inhibitor protein (RKIP) in the proliferation of LX-2 human hepatic stellate cells. Methods The recombinant plasmid siRNA-RKIP was transfected into LX-2 cells. Five days later, the stably transfected cells were screened and cultured. MTT assay was used to detect cell proliferation after RKIP was silenced. Cell apoptosis and cell cycle distribution were evaluated by flow cytometry. The expressions of α-smooth muscle actin (α-SMA) and collagen type 1 (Col1) mRNA were detected by quantitative real-time PCR. The expressions of RKIP, α-SMA, Col1 and extracellular signal-regulated kinases/mitogen-activated protein kinase (ERK/MAPK) signaling pathway related proteins were assessed by Western blot analysis. Results Compared with the control group, knockdown of RKIP significantly induced LX-2 cell proliferation, reduced cell apoptosis, raise cell number in G2, and increased the proteins and mRNA expressions of Col1 and α-SMA. Moreover, low-expression of RKIP significantly enhanced the phosphorylation of ERK/MAPK. Conclusion Knockdown of RKIP promotes LX-2 cell proliferation; its mechanism is related to the activation of ERK/MAPK signaling pathway.