Isolation and identification of tumor-initiating cell properties in human gallbladder cancer cell lines using the marker cluster of differentiation 133

The present study aimed to isolate and identify the properties of the cluster of differentiation (CD)133+ subset in human gallbladder cancer cells. The CD133+ and CD133- subpopulations of the GBC-SD cell line were separated using immunomagnetic separation, and the biological features of the two subpopulations were analyzed in vitro and in vivo. In particular, the present study aimed to determine whether the two subpopulations were resistant to anti-tumor reagents and to identify the underlying molecular mechanisms involved. Following cell sorting of GBC-SD cells using immunomagnetic beads, 90.2±2% of cells were identified as CD133+. Immunofluorescence confirmed that CD133 was expressed at higher levels in the Cd133+ group compared with the CD133- group. The proliferation of the CD133+ group was significantly increased compared with the CD133- group in vitro and in vivo. Following treatment with fluorouracil or gemcitabine, cells in the CD133+ group exhibited a decreased sensitivity to these drugs. The number of transmembrane cells was significantly increased in the CD133+ group compared with the CD133- group. In addition, the expression levels of ATP binding cassette subfamily G member 2, CD44, C-X-C motif chemokine receptor 4 (CXCR4), phosphorylated-protein kinase B (Akt) and CD133 in the CD133+ group were significantly increased, compared with those in the CD133- group. In CD133+ GBC-SD cells, stromal cell-derived factor 1α (SDF-1α) or treatment with AMD3100, an inhibitor of CXCR4, promotes or suppresses the SDF-1α/CXCR4 axis, respectively, resulting in increased or decreased CD133 expression through the Akt signaling pathway. Inhibition of the Akt signaling pathway resulted in decreased CD133 expression in GBC-SD cells. Immunomagnetic beads were successfully used for isolation of the CD133+ subset from GBC-SD cells. Furthermore, the CD133+ subset revealed an increased potential for tumor formation, cell proliferation, invasion and resistance to chemotherapeutic agents with expression of stem cell-associated genes. Therefore, in GBC-SD cells, the CXCR4/Akt/CD133 signaling pathways may be activated.