Basic Study
Copyright ©The Author(s) 2023. Published by Baishideng Publishing Group Inc. All rights reserved.
World J Gastroenterol. Jun 21, 2023; 29(23): 3606-3621
Published online Jun 21, 2023. doi: 10.3748/wjg.v29.i23.3606
BMI-1 activates hepatic stellate cells to promote the epithelial-mesenchymal transition of colorectal cancer cells
Zhong-Yang Jiang, Xi-Mei Ma, Xiao-Hui Luan, Zhen-Yu Liuyang, Yi-Yang Hong, Yuan Dai, Qing-Hua Dong, Guan-Yu Wang
Zhong-Yang Jiang, Xiao-Hui Luan, Zhen-Yu Liuyang, Guan-Yu Wang, Department of General Surgery, Sir Run Run Shaw Hospital, School of Medicine, Zhejiang University, Hangzhou 310016, Zhejiang Province, China
Xi-Mei Ma, Department of Emergency, The Second Affiliated Hospital of Zhejing University, Hangzhou 310016, Zhejiang Province, China
Yi-Yang Hong, Yuan Dai, Qing-Hua Dong, Biomedical Research Center, Sir Run Run Shaw Hospital, School of Medicine, Zhejiang University, Hangzhou 310016, Zhejiang Province, China
Qing-Hua Dong, Key Laboratory of Cancer Prevention and Intervention, China National Ministry of Education, Hangzhou 310009, Zhejiang Province, China
Author contributions: Jiang ZY, Dong QH, and Wang GY conceived and designed the study; Jiang ZY, Ma XM, Luan XH, Liuyang ZY, Hong YY, and Dai Y performed the research, and collected and analyzed the data; Jiang ZY, Dong QH, and Wang GY wrote the manuscript; All authors read and approved the final manuscript.
Supported by National Natural Science Foundation of China, No. 81472213; the Health Commission of Zhejiang Province, No. 2019ZD010 and No. 2019ZD029; the Science Technology Department of Zhejiang Province, No. LGF20H220001; and the Zhejiang Provincial Administration of Traditional Chinese Medicine, No. 2021ZA088.
Institutional review board statement: This study was reviewed and approved by the Ethics Committee of Sir Run Run Shaw Hospital affiliated with the Zhejiang University School of Medicine, No. 2023-404-01.
Institutional animal care and use committee statement: All animal experiments were performed in accordance with the guidelines of the Committee on the Ethics of Animal Experiments of Zhejiang University, No. ZJU20220447.
Informed consent statement: All study participants or their legal guardian provided informed written consent about personal and medical data collection prior to study enrolment.
Conflict-of-interest statement: All the authors report no relevant conflicts of interest for this article.
Data sharing statement: No additional data are available.
ARRIVE guidelines statement: The authors have read the ARRIVE guidelines, and the manuscript was prepared and revised according to the ARRIVE guidelines.
Open-Access: This article is an open-access article that was selected by an in-house editor and fully peer-reviewed by external reviewers. It is distributed in accordance with the Creative Commons Attribution NonCommercial (CC BY-NC 4.0) license, which permits others to distribute, remix, adapt, build upon this work non-commercially, and license their derivative works on different terms, provided the original work is properly cited and the use is non-commercial. See: https://creativecommons.org/Licenses/by-nc/4.0/
Corresponding author: Guan-Yu Wang, MD, PhD, Surgeon, Department of General Surgery, Sir Run Run Shaw Hospital, School of Medicine, Zhejiang University, No. 3 East Qingchun Road, Hangzhou 310016, Zhejiang Province, China. wangguanyu@zju.edu.cn
Received: February 1, 2023
Peer-review started: February 1, 2023
First decision: February 12, 2023
Revised: February 25, 2023
Accepted: May 4, 2023
Article in press: May 4, 2023
Published online: June 21, 2023
Abstract
BACKGROUND

Activated hepatic stellate cells (aHSCs) are the major source of cancer-associated fibroblasts in the liver. Although the crosstalk between aHSCs and colorectal cancer (CRC) cells supports liver metastasis (LM), the mechanisms are largely unknown.

AIM

To explore the role of BMI-1, a polycomb group protein family member, which is highly expressed in LM, and the interaction between aHSCs and CRC cells in promoting CRC liver metastasis (CRLM).

METHODS

Immunohistochemistry was carried out to examine BMI-1 expression in LM and matched liver specimens of CRC. The expression levels of BMI-1 in mouse liver during CRLM (0, 7, 14, 21, and 28 d) were detected by Western blotting (WB) and the quantitative polymerase chain reaction (qPCR) assay. We overexpressed BMI-1 in HSCs (LX2) by lentivirus infection and tested the molecular markers of aHSCs by WB, qPCR, and the immunofluorescence assay. CRC cells (HCT116 and DLD1) were cultured in HSC-conditioned medium (LX2 NC CM or LX2 BMI-1 CM). CM-induced CRC cell proliferation, migration, epithelial-mesenchymal transition (EMT) phenotype, and transforming growth factor beta (TGF-β)/SMAD pathway changes were investigated in vitro. A mouse subcutaneous xenotransplantation tumor model was established by co-implantation of HSCs (LX2 NC or LX2 BMI-1) and CRC cells to investigate the effects of HSCs on tumor growth and the EMT phenotype in vivo.

RESULTS

Positive of BMI-1 expression in the liver of CRLM patients was 77.8%. The expression level of BMI-1 continued to increase during CRLM in mouse liver cells. LX2 overexpressed BMI-1 was activated, accompanied by increased expression level of alpha smooth muscle actin, fibronectin, TGF-β1, matrix metalloproteinases, and interleukin 6. CRC cells cultured in BMI-1 CM exhibited enhanced proliferation and migration ability, EMT phenotype and activation of the TGF-β/SMAD pathway. In addition, the TGF-βR inhibitor SB-505124 diminished the effect of BMI-1 CM on SMAD2/3 phosphorylation in CRC cells. Furthermore, BMI-1 overexpressed LX2 HSCs promoted tumor growth and the EMT phenotype in vivo.

CONCLUSION

High expression of BMI-1 in liver cells is associated with CRLM progression. BMI-1 activates HSCs to secrete factors to form a prometastatic environment in the liver, and aHSCs promote proliferation, migration, and the EMT in CRC cells partially through the TGF-β/SMAD pathway.

Keywords: BMI-1, Hepatic stellate cells, Colorectal cancer, Liver metastasis, Epithelial-mesenchymal transition

Core Tip: This study revealed that BMI-1 was upregulated in liver cells during colorectal cancer (CRC) liver metastasis. BMI-1-activated LX2 hepatic stellate cells (HSCs) promoted CRC cell proliferation, migration, and the epithelial-mesenchymal transition both in vitro and in vivo. Mechanistically, transforming growth factor beta 1 was increased in BMI-1 overexpressed LX2 HSCs, and triggered the phosphorylation of downstream SMAD2/3 in CRC cells and the interaction of activated HSCs and CRC cells, thereby further promoting CRC progression.