Characterization of cancer stem cells from different grades of human colorectal cancer

Abstract

Colorectal cancer (CRC) is one of the most common solid tumors worldwide. Recent evidence suggests that a population of cancer cells, called cancer stem cells (CSCs), is responsible for tumor heterogeneity, invasion, metastasis, therapeutic resistance, and recurrence of CRC. The isolation and characterization of CSCs using cell surface markers have been reported previously with varying results. In this study, we investigated a panel of four putative CSC markers, CD44, CD24, CD166, and EpCAM, to define CRC-CSC. Paraffin embedded tissue samples from different grades of primary, untreated CRC were analyzed for the expression of four CSC markers CD44, CD326, CD24, and CD166, using immunohistochemistry. Flow cytometric analysis of CRC-CSC from HT29 (low grade) and HCT116 (high grade) human colorectal cancer cell lines was done. Marker-based isolation of CSC and non-CSC-bulk-tumor cells from HT29 was done using FACS, and tumor sphere assay was performed. There was a statistically significant difference (p < 0.05) in the expression of CD44, CD326, and CD166 between cases and controls. A novel cutoff distribution of CD44 and CD166 was suggested to help for better immunohistochemical analysis of CRC. Higher prevalence of CSC was seen in high-grade CRC as compared to low-grade CRC. Sorted and cultured CD44 + CD166+ cells formed tumor spheres, suggesting that these cells, having properties of self renewal and anchorage independent proliferation, were in fact CSC. Hence, CD44 and CD166 may serve as good CRC-CSC markers when used together with novel cutoff immunohistochemistry (IHC) expression levels.

Molecular profiling of ALDH1+ colorectal cancer stem cells reveals preferential activation of MAPK, FAK, and oxidative stress pro-survival signalling pathways

“…Treatment choices for patients with CRC assume homogeneity in tumour mass; therefore it is plausible that conventional chemotherapy and radiotherapy sometimes fail in tumour eradication. Alternatively, several studies have demonstrated that solid tumours including CRC exhibit cellular heterogeneity [ 5 , 6 ], which may reflect different origin of cells at the time of tumour origination [ 7 ]. Furthermore, recently the presence within solid tumours of a minor subset of cells termed cancer stem-like cells (CSCs) or tumour-initiating cells (TICs), which exhibit self-renewal and differentiation capabilities, has been demonstrated and suggested to be responsible for tumour maintenance, metastasis and drug resistance [ 6 , 8 , 9 ].…”

CD44 is overexpressed and correlated with tumor progression in gallbladder cancer

“… 11 , 12 Furthermore, many typical characteristic markers of CSCs have been observed at the cell membrane surface, and elevated expression of some specific cell surface proteins has been proven to facilitate tumor initiation, progression and poor clinical outcomes. 13 Among these proteins, cluster of differentiation 44 (CD44), as the principal receptor, has been demonstrated to contribute to cell proliferation, invasion and metastasis of CSCs. 14 Increasing evidence has indicated that CD44 is extensively overexpressed in various cancer types including prostate cancer, 15 triple-negative breast cancer, 16 lung cancer 17 and pancreatic cancer, 18 and correlated with aggressive biological behaviors and poor prognostic characteristics.…”

Clinicopathological, prognostic and predictive value of CD166 expression in colorectal cancer: a meta-analysis

“…As a CSC marker, CD166 expression may be involved in the progression, metastasis and prognosis of several malignant tumors [ 16 , 35 , 36 ]. Immunohistochemical staining of CD166 was found to be frequently expressed in CRC [ 18 , 20 , 21 ], with frequency ranging from 30.6% [ 19 ] to 76.3% [ 24 ]. CRC generally derives from normal colonic mucosa that turns into adenomas; then these adenomas progress to malignancy through genetic and environment factors [ 37 , 38 ].…”