Table 5.

Cells representing “cancer stem cell” phenotype obtained from colorectal cancer patients

Origin of CSC	Hallmarks of CSC	Drug resistance	Ref.
Tumorigenic cells in colon cancer were isolated by mechanical and enzymatic dissociation. CD133 cells were separated magnetically or using a cell sorter	Tumorigenic cells in colon cancer were in the high-density CD133+ cells. CD133+ cells readily reproduced the original tumor in nude mice, but CD133- cells did not form tumors	No description	Ricci-Vitiani et al.[54]
Colon cancer specimens were sliced and enzymatically dissociated. CSC cultures were made in a human embryonic stem cell medium with modification	Cell sorting was done on a MoFlo High Speed Cell Sorter using CD133 and EpCAM antibodies. Colon CSCs could be isolated and proliferate under serum-free and stem cell culture conditions. These spheroid forming cells express well-known CSC markers, such as CD133, CD166, CD44, and EpCAM	Relatively larger (> 70%) cell growth of spheroidal cells (showing CSC characteristics) was observed in irinotecan concentrations of 2 and 4 mM. Growth of differentiated cells (not showing CSC characteristics) at 2 and 4 mM was only 35%-40%. At 51 mM irinotecan, growth of spheroid cells and differentiated cells were approximately 35% and 10%, respectively	Fang et al.[55]
Human colon cancer cell line, COLO 205, cells were maintained in a medium free of serum	Culture under a serum-free condition for 7 days, and then CD133 expression was confirmed (CSC-like). The CSC-like cells express CYP3A4 and ALDH1A1 as compared with standard medium containing serum	CSC-like cells showed higher viability when exposed to oxaliplatin, cisplatin, gemcitabine, vinblastine, and etoposide	Olszewski et al.[56]
Patient-derived colorectal cancer cells (CRC1) maintained as spheroids	CRC1 cells maintained as spheroids showed a higher expression of ALDH activity, a CSC marker, than cells in 2D culture	Spheroidal cells were 2.44-fold more resistant to combinatory treatment of 5-fluorouracil and SN-38 than 2D cells	Planque et al.[58]

CSC: Cancer stem cell.