Basic Study
Copyright ©The Author(s) 2021. Published by Baishideng Publishing Group Inc. All rights reserved.
World J Gastroenterol. Apr 21, 2021; 27(15): 1578-1594
Published online Apr 21, 2021. doi: 10.3748/wjg.v27.i15.1578
Leucine-rich repeat-containing G protein-coupled receptor 5 marks different cancer stem cell compartments in human Caco-2 and LoVo colon cancer lines
Samah Abdulaali Alharbi, Dmitry A Ovchinnikov, Ernst Wolvetang
Samah Abdulaali Alharbi, Physiology Department, College of Medicine, Umm Al-Qura University, Makkah 24231, Saudi Arabia
Samah Abdulaali Alharbi, Ernst Wolvetang, Department of Stem Cell Engineering Group, Australian Institute for Bioengineering and Nanotechnology, The University of Queensland, Brisbane 4072, QLD, Australia
Dmitry A Ovchinnikov, Australian Institute for Bioengineering and Nanotechnology, The University of Queensland, Brisbane 4072, QLD, Australia
Author contributions: Alharbi SA contributed investigation, methodology, formal analysis, visualization, preparation and original draft preparation; Ovchinnikov DA contributed conceptualization, methodology and supervision; Wolvetang E contributed conceptualization, supervision, funding, acquisition, project administration and resources and reviewed and edited the manuscript.
Institutional review board statement: The study was reviewed and approved by the Institutional Review Board at The University of Queensland (approval No. 2019000159).
Institutional animal care and use committee statement: All animal experiments conformed to the internationally accepted principles for the care and use of laboratory animals, The Australian Institute of Bioengineering and Nanotechnology, Brisbane; Australia (approval No. AIBN/065/12/SCA/LEJEUNE/KACST).
Conflict-of-interest statement: All authors have nothing to disclose.
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:
Corresponding author: Samah Abdulaali Alharbi, PhD, Assistant Professor, Senior Scientist, Physiology Department, College of Medicine, Umm Al-Qura University, Prince Sultan bin AbdulAziz road, Makkah 24231, Saudi Arabia.
Received: December 1, 2020
Peer-review started: December 1, 2020
First decision: December 21, 2020
Revised: January 22, 2021
Accepted: February 24, 2021
Article in press: February 24, 2021
Published online: April 21, 2021
Research background

The intestinal crypt-villus structure harbors two distinct pools of putative stem cells, the active [leucine-rich repeat-containing G protein-coupled receptor 5 (LGR5)+ cells] and the quiescent stem cell populations (B lymphoma Moloney murine leukemia virus insertion region 1 homolog+ or telomerase reverse transcriptase+ cells). Current evidence indicates that CRC is indeed a disease of colon stem cells that are resistant to current therapeutics and can rapidly proliferate to re-establish the tumor. Furthermore, it was reported that colon cancer carcinoma specimens contain a subset of LGR5-expressing stem cells. Human colon cancer cell lines, such as Caco-2 and LoVo, are extensively used in drug screening and colon cancer research and express high levels of LGR5.

Research motivation

To establish criteria for the selection of suitable cell lines for drug discovery and reveal potential variability between colon cell lines, we here identify the cancer stem cell (CSC) population(s) within colon cancer cell lines, quantify differences in gene expression signatures in these cells, and assess their proliferative and tumorgenicity capacities.

Research objectives

The present study aimed to isolate cells expressing LGR5 in Caco-2 and LoVo colon cancer cell lines and investigate whether these cells constitute the CSC compartments in these cell lines. This was achieved through the creation of a transgenic proliferating stem cell-specific reporter construct based on the proximal promoter of LGR5 gene.

Research methods

Using a portable fluorescent reporter construct based on a conserved fragment of the LGR5 promoter, subpopulations of cells from the colon cancer cell lines (Caco-2 and LoVo) were sorted into three cell compartments expressing different levels of LGR5 (high-, low-, and no-expression of LGR5). Next these cell compartments were characterized based on their gene expression signatures, proliferation, and tumorgenicity properties.

Research results

Cells expressing high levels of LGR5 with Caco-2 colon cancer cell line appear to represent a CSC-like population. In contrast, in the LoVo cell line, the LGR5 negative fraction possessed some features of the intestinal stem cells, e.g., a specific gene expression signature, suggesting that this cell line was likely derived from a CSC population other than LGR5+ cells.

Research conclusions

LGR5 marks the stem cell compartments of the Caco-2, but not LoVo, cell lines. Thus, it would appear that different colon cancer lines possess properties of different stem cell compartments. The portable LGR5 reporter outlined in this study constitutes a valuable tool for the identification and purification of LGR5-expressing cells from mixed cell populations.

Research perspectives

The portable LGR5 reporter described in this study constitutes a valuable tool for the identification and purification of LGR5-expressing cells from mixed cell populations.