Basic Study
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World J Gastroenterol. Sep 14, 2022; 28(34): 4993-5006
Published online Sep 14, 2022. doi: 10.3748/wjg.v28.i34.4993
Oxidized low-density lipoprotein stimulates CD206 positive macrophages upregulating CD44 and CD133 expression in colorectal cancer with high-fat diet
Shi-Min Zheng, Hao Chen, Wei-Hong Sha, Xiao-Fen Chen, Jian-Bin Yin, Xiao-Bo Zhu, Zhong-Wen Zheng, Juan Ma
Shi-Min Zheng, Hao Chen, Wei-Hong Sha, Xiao-Fen Chen, Xiao-Bo Zhu, Zhong-Wen Zheng, Juan Ma, Department of Gastroenterology and Hepatology, Guangdong Provincial People’s Hospital, Guangdong Academy of Medical Sciences, Guangzhou 510080, Guangdong Province, China
Shi-Min Zheng, Wei-Hong Sha, Xiao-Fen Chen, Juan Ma, Medical College, Shantou University, Shantou 515041, Guangdong Province, China
Wei-Hong Sha, Jian-Bin Yin, Juan Ma, Medical College, Southern Medical University, Guangzhou 510515, Guangdong Province, China
Jian-Bin Yin, Center for Orthopaedic Surgery, The Third Affiliated Hospital of Southern Medical University, Guangzhou 510630, Guangdong Province, China
Author contributions: Zheng SM, Sha WH, Chen H, and Ma J designed and coordinated the study; Zheng SM, Chen XF, Yin JB, Zhu XB, and Zheng ZW performed the experiments; Zheng SM and Yin JB acquired and analyzed the data; Chen XF, Zhu XB, and Zheng ZW interpreted the data; Zheng SM, Sha WH, and Chen H wrote the manuscript; and all authors approved the final version of the article.
Supported by Science and Technology Program of Guangzhou, No. 202102080007.
Institutional review board statement: The institutional review board of the Guangdong General Hospital approved the study protocol. All procedures performed in studies involving human participants were in accordance with the ethical standards of the institutional and national research committee and with the 1964 Helsinki declaration and its later amendments or comparable ethical standards.
Institutional animal care and use committee statement: The animal protocol was designed to minimize pain or discomfort to the animals. The animals were acclimatized to laboratory conditions (23 °C, 12 h/12 h light/dark, 50% humidity, ad libitum access to food and water) for 2 wk prior to experimentation.
Conflict-of-interest statement: All the authors report no relevant conflicts of interest for this article.
Data sharing statement: Technical appendix, statistical code, and dataset available from the corresponding author at email: Participants gave informed consent for data sharing.
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:
Corresponding author: Juan Ma, PhD, Doctor, Department of Gastroenterology and Hepatology, Guangdong Provincial People’s Hospital, Guangdong Academy of Medical Sciences, No. 106, Zhongshan 2nd Road, Guangzhou 510080, Guangdong Province, China.
Received: March 14, 2022
Peer-review started: March 14, 2022
First decision: April 11, 2022
Revised: May 15, 2022
Accepted: August 22, 2022
Article in press: August 22, 2022
Published online: September 14, 2022
Research background

Oxidized low-density lipoprotein (ox-LDL), abnormally increased in the serum of patients with colorectal cancer (CRC) associated with a high-fat diet (HFD), may be one of the risk factors for CRC. Ox-LDL exerts a regulatory effect on macrophages, is associated with cancer stem cells, and may regulate CRC through the tumor microenvironment. The role of ox-LDL in CRC remains unclear. It is essential to explore the function of ox-LDL to explore the pathogenesis of HFD associated CRC.

Research motivation

The expression of ox-LDL in human colorectal cancerous tissues and colorectal tissues of hyperlipidemic mice was detected, and the function of ox-LDL in the macrophages in the tumor microenvironment was explored. Our key point is that ox-LDL up-regulates CD44 and CD133 in HFD associated CRC, which is mediated by macrophages. Our study will provide a new idea for the mechanism of HFD associated CRC.

Research objectives

The study aimed to investigate the role of ox-LDL through macrophage in HFD associated CRC.

Research methods

The expression of ox-LDL and CD206 was detected in colorectal tissues of CRC patients with hyperlipidemia and HFD-fed mice by immunofluorescence. We stimulated macrophages with 20 ug/mL ox-LDL and assessed the expression levels of CD206 and cytokines by cell fluorescence and quantitative polymerase chain reaction. We further knocked down LOX-1, the surface receptor of ox-LDL, to confirm the function of ox-LDL in macrophages. Then, LoVo cells were co-cultured with the stimulated macrophages to analyze the CD44 and CD133 expression by western blot.

Research results

The expression of ox-LDL and CD206 was significantly increased in the stroma of colorectal tissues of CRC patients with hyperlipidemia, and also upregulated in the HFD-fed mice. Moreover, an increased level of CD206 and decreased level of inducible nitric oxide synthase were observed in macrophages after the continuous stimulation of ox-LDL. Such effects were inhibited when the surface receptor LOX-1 was knocked down in macrophages. Ox-LDL could induce CD206+ macrophages, which resulted in high expression of CD44 and CD133 in co-cultured LoVo cells.

Research conclusions

Our study found that HFD could induce ox-LDL accumulation in CRC tissue, suggesting the regulatory role of ox-LDL in the microenvironment of CRC. Continuous stimulation of macrophages with ox-LDL induced CD206+ macrophages, which could further promote the increase of CD44 and CD133 levels in CRC cells.

Research perspectives

Our future study will collect more samples. We look forward to make a convincing analysis to identify the correlation between ox-LDL and progression and survival of the enrolled patients in the near future. We will explore the potential signal pathways related to ox-LDL promoting M2-type macrophages by using the technology of single cell sequencing and/or RNA-Seq assay. We are confident that it will provide exciting data in the near future.