A Validation Study of CD133 as a Reliable Marker for Identification of Colorectal Cancer Stem-Like Cells

Colorectal carcinoma (CRC) is maintained by putative colorectal cancer stem-like cells (CRC-CSCs) that are responsible for CRC metastasis and relapse. Targeting these CSCs can be an effective treatment of CRC. However, reliable identification of CRC-CSCs remains controversial due to the absence of specific markers. It is assumed that glycoprotein CD133 can serve as a useful marker for identification of CRC-CSCs. In this study, we employed CD133 as a marker to identify CRC-CSCs in human (LoVo, HCT116, and SW620) and mouse (CT26) CRC cell lines. In these lines, CD133⁺ cells were isolated and identified by magnetic-activated cell sorting and flow cytometry. Proliferation, colony formation, and drug resistance of CD133⁺ cells were analyzed in vitro, and their tumorigenicity was determined in vivo on mice. Proliferation, colony-forming ability, drug resistance, and tumorigenicity of CD133⁺ cells were higher than those of CD133^- cells. Thus, cultured CD133⁺ cells had the characteristics of CSCs. Hence, glycoprotein CD133 is a reliable marker to identify CRC-CSCs. These results can be used for designing a novel therapeutic target in CRC treatment.