Original Article
Copyright ©2013 Baishideng Publishing Group Co., Limited. All rights reserved.
World J Gastroenterol. Nov 21, 2013; 19(43): 7680-7695
Published online Nov 21, 2013. doi: 10.3748/wjg.v19.i43.7680
8-bromo-7-methoxychrysin inhibits properties of liver cancer stem cells via downregulation of β-catenin
Mei-Fang Quan, Li-Hong Xiao, Zhi-Hong Liu, Hui Guo, Kai-Qun Ren, Fei Liu, Jian-Guo Cao, Xi-Yun Deng
Mei-Fang Quan, Li-Hong Xiao, Kai-Qun Ren, Fei Liu, Jian-Guo Cao, Xi-Yun Deng, Medical College, Hunan Normal University, Changsha 410013, Hunan Province, China
Zhi-Hong Liu, Hui Guo, Department of pathology, Hunan Provincial Tumor Hospital, Changsha 410013, Hunan Province, China
Author contributions: Quan MF and Xiao LH contributed equally to this work; Quan MF, Xiao LH, Liu ZH, Guo H, Ren KQ and Liu F performed the majority of experiments; Cao JG designed the study and wrote the manuscript; Deng XY participated in the study and helped to draft the manuscript.
Supported by National Natural Science Foundation of China, No. 81172375; and Scientific Research Fund of Hunan Normal University, No. 81105
Correspondence to: Jian-Guo Cao, Professor, Medical College, Hunan Normal University, Yuelu District, Changsha 410013, Hunan Province, China. caojianguo2005@126.com
Telephone: +86-731-88912434 Fax: +86-731-88912417
Received: May 22, 2013
Revised: September 13, 2013
Accepted: September 16, 2013
Published online: November 21, 2013
Abstract

AIM: To evaluate whether 8-bromo-7-methoxychrysin (BrMC), a synthetic analogue of chrysin, inhibits the properties of cancer stem cells derived from the human liver cancer MHCC97 cell line and to determine the potential mechanisms.

METHODS: CD133+ cells were sorted from the MHCC97 cell line by magnetic activated cell sorting, and amplified in stem cell-conditioned medium to obtain the enriched CD133+ sphere forming cells (SFCs). The stem cell properties of CD133+ SFCs were validated by the tumorsphere formation assay in vitro and the xenograft nude mouse model in vivo, and termed liver cancer stem cells (LCSCs). The effects of BrMC on LCSCs in vitro were evaluated by MTT assay, tumorsphere formation assay and transwell chamber assay. The effects of BrMC on LCSCs in vivo were determined using a primary and secondary xenograft model in Balb/c-nu mice. Expressions of the stem cell markers, epithelial-mesenchymal transition (EMT) markers and β-catenin protein were analyzed by western blotting or immunohistochemical analysis.

RESULTS: CD133+ SFCs exhibited stem-like cell properties of tumorsphere formation and tumorigenesis capacity in contrast to the parental MHCC97 cells. We found that BrMC preferentially inhibited proliferation and self-renewal of LCSCs (P < 0.05). Furthermore, BrMC significantly suppressed EMT and invasion of LCSCs. Moreover, BrMC could efficaciously eliminate LCSCs in vivo. Interestingly, we showed that BrMC decreased the expression of β-catenin in LCSCs. Silencing of β-catenin by small interfering RNA could synergize the inhibition of self-renewal of LCSCs induced by BrMC, while Wnt3a treatment antagonized the inhibitory effects of BrMC.

CONCLUSION: BrMC can inhibit the functions and characteristics of LCSCs derived from the liver cancer MHCC97 cell line through downregulation of β-catenin expression.

Keywords: Liver cancer, Cancer stem cell, 8-bromo-7-methoxychrysin, Self-renewal, β-catenin

Core tip: We successfully obtained liver cancer stem cells (LCSCs) from the liver cancer MHCC97 cell line by employing the combination of magnetic activated cell sorting and tumorsphere culture. We showed for the first time that 8-bromo-7-methoxychrysin (BrMC), a synthetic analogue of chrysin, could preferentially inhibit proliferation and self-renewal, suppress epithelial-mesenchymal transition and invasion of LCSCs, and further eradicate LCSCs in vivo. The results of this study support the use of BrMC for liver cancer chemoprevention or chemotherapy.