Cooperation of side population cells with CD133 to enrich cancer stem cells in a laryngeal cancer cell line

Background. The identification of cancer stem cells (CSCs) in laryngeal cancer remains a dilemma. Our previous studies identified CD133(+) subgroup and side population (SP) cells in the laryngeal cancer cell line, human epithelial type-2 (Hep-2). Although both cell types shared some tumor-initiating properties, they were heterogeneous. In this study, we further enriched CSCs from this cell line. Methods. We divided the SP cells into CD133(+) SP and CD133(-) SP cells by combining SP and CD133, and compared CSC-associated properties between the 2 subgroups. Results. SP cells contained CD133(+) SP and CD133(-) SP, and CD133(+) SP cells manifested preferential expression of self-renewal genes, higher capacity for proliferation, differentiation, and clone and spheroid formation, enhanced resistance to radiation and chemotherapy, and greater tumorigenicity compared with CD133(-) SP cells. Conclusion. The CD133(+) SP subpopulation is enriched in CSCs compared with the CD133(-) SP subgroup, suggesting that the combination of SP and CD133 can further purify CSCs in the Hep-2 cell line. (C) 2013 Wiley Periodicals, Inc.