Growing evidences indicate that tumor regrowth and invasion refer a small subpopulation of tumor cells called cancer stem cells (CSCs). Autophagy is an essential catabolic process for cell homeostasis that involves in cell survival and death and also development of various human diseases including cancer. Here we aimed to investigate the effect of autphagy on the subpopulation of CD44 C /CD24 À/low phenotype MCF7 and Hep-2 cells. CD44 C /CD24 À/low cells were isolated from MCF7 and Hep-2 cell

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... ltures by using fluorescence-activated cell sorting (FACS). The CD44 C /CD24 À/low and the original cells were separately treated with 20 mM of C2 ceramide for 24 hours in order to stimulation of autophagy. LC3 proteins aggregation was monitored to evaluate autophagy in the cells by using LC3 targeted immunofluorescence staining assay. Subpopulation of CD44 C /CD24 À/low cells in total cultures were investigated by flow cytometry analysis and eventually statistics were carried out. Results showed an enhanced aggregation of LC3 proteins in the cells and also CD44 C /CD24 À/low cells under effect of C2 ceramide. Moreover, the subpopulation of CD44 C /CD24 À/low cells were found significantly lower in the cells cultures treated with C2 ceramide in comparison with negative controls. The results elucidated that CD44 C /CD24 À/low MCF7 and Hep-2 cells were susceptible to autophagy stimulatory reagent C2 ceramide. Additionally, our results suggest that CD44 C /CD24 À/low cell subpopulation in the cell cultures is reduced under autophagic condition. Therefore, we suppose that autophagy may has a negative impact on the breast and Larynx cancer stem cells self-renewal potency or expression of CD44 and CD24 cell surface markers, however further studies are needed to reveal the exact mechanism.