Basic Research
Copyright ©2008 The WJG Press and Baishideng. All rights reserved.
World J Gastroenterol. Nov 21, 2008; 14(43): 6673-6680
Published online Nov 21, 2008. doi: 10.3748/wjg.14.6673
Activation of canonical Wnt signaling pathway promotes proliferation and self-renewal of rat hepatic oval cell line WB-F344 in vitro
Ying Zhang, Xin-Min Li, Fu-Kui Zhang, Bao-En Wang
Ying Zhang, Xin-Min Li, Fu-Kui Zhang, Bao-En Wang, Liver Research Center, Beijing Friendship Hospital, Capital Medical University, Beijing 100050, China
Author contributions: Zhang Y, Wang BE designed the research; Zhang Y, Zhang FK, Li XM performed the research; Zhang Y, Li XM analyzed the data; Zhang Y wrote the paper.
Correspondence to: Bao-En Wang, Professor, Liver Research Center, Beijing Friendship Hospital, Capital Medical University, Beijing 100050, China. wangbbee@126.com
Telephone: +86-10-63164411 Fax: +86-10-63164411
Received: August 25, 2008
Revised: October 15, 2008
Accepted: October 22, 2008
Published online: November 21, 2008
Abstract

AIM: To investigate the effect of activation of canonical Wnt signaling pathway on the proliferation and differentiation of hepatic oval cells in vitro.

METHODS: WB-F344 cells were treated with recombinant Wnt3a (20, 40, 80, 160, 200 ng/mL) in serum-free medium for 24 h. Cell proliferation was measured by Brdu incorporation analysis; untreated WB-F344 cells were taken as controls. After treatment with Wnt3a (160 ng/mL) for 24 h, subcellular localization and protein expression of β-catenin in WB-F344 cells treated and untreated with Wnt3a were examined by immunofluorescence staining and Western blot analysis. CyclinD1 mRNA expression was determined by semi-quantitative reverse-transcript polymerase chain reaction (RT-PCR). The mRNA levels of some phenotypic markers (AFP, CK-19, ALB) and two hepatic nuclear factors (HNF-4, HNF-6) were measured by RT-PCR. Expressions of CK-19 and AFP protein were detected by Western blot analysis.

RESULTS: Wnt3a promoted proliferation of WB-F344 cells. Stimulation of WB-F344 cells with recombinant Wnt3a resulted in accumulation of the transcriptional activator β-catenin, together with its translocation into the nuclei, and up-regulated typical Wnt target gene CyclinD1. After 3 d of Wnt3a treatment in the absence of serum, WB-F344 cells retained their bipotential to express several specific phenotypic markers of hepatocytes and cholangiocytes, such as AFP and CK-19, following activation of the canonical Wnt signaling pathway.

CONCLUSION: The canonical Wnt signaling pathway promotes proliferation and self-renewal of rat hepatic oval cells.

Keywords: Canonical Wnt signaling pathway, Oval cells, Cell proliferation, Self-renewal of cells