Abstract

Background/Aims

Hepatocyte growth factor (HGF) regulates proliferation of hepatic stem cells. Transcription factor nuclear factor kappa B (NF-κB) has been demonstrated as a key mediator for cell growth regulation. We investigated the role of NF-κB in HGF-mediated cellular proliferation responses in a rat liver-derived hepatic stem-like cell line WB-F344.

Methods

Cell proliferation was determined by incorporation of [³H]thymidine. Phosphorylation of ERK1/2, p38 MAPK, Akt and IκBα by HGF stimulation was detected by Western blotting. NF-κB activation was determined by electrophoretic mobility shift assay and NF-κB-mediated SEAP reporter assay. NF-κB activation was inhibited by treatment with an IκBα dominant-negative vector or inhibitor BAY-11-7082.

Results

We found that stimulation of WB-F344 cells with HGF promoted cell proliferation and effectively protected WB-F344 cells from apoptosis induced by TNF-α. We also observed activation of ERK1/2, p38 MAPK, Akt and NF-κB signaling pathways by HGF in WB-F344 cells. HGF-induced cell proliferation was partly blocked by pre-treatment of the cells with inhibitors against MEK1 or p38 MAPK, and completely blocked using an inhibitor for NF-κB activity. Furthermore, it was demonstrated that IκB mutant that suppressed NF-κB activity completely blocked HGF-induced cell proliferation.

Conclusions

NF-κB activity is required for HGF-induced proliferation in hepatic stem-like cell line WB-F344, and this activity requires ERK1/2 and p38 MAPK pathways.
Author Keywords: Author Keywords: Hepatocyte growth factor; Nuclear factor κB; Proliferation; Hepatic stem cell
ActD, actinomycin D; DMEM, Dulbecco's modified Eagle's medium; DMSO, dimethyl sulfoxide; EDTA, ethylene diaminetetracetic acid; EMSA, electrophoretic mobility shift assay; ERK, extracellular signal-regulated kinase; FACS, fluorescence-activated cell sorting; FBS, fetal bovine serum; G418, neomycin; HGF, hepatocyte growth factor; IκB, inhibitor of κB; MAPK, mitogen-activated protein kinase; MEK, mitogen-activated protein kinase/extracellular signal-regulated kinase; NF-κB, nuclear factor κB; PBS, phosphate-buffered saline; PI3K, phosphatidylinositol 3-kinase; p38 MAPK, p38 mitogen-activated protein kinase; SDS, sodium dodecyl sulfate; SEAP, secretory alkaline phosphatase; STAT, signal transducer and activator of transcription; TNF-α, tumor necrosis factor-α; WB-F344, rat hepatic stem-like cell line; WT, wild-type

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