According to cancer stem cell theory, cancer stem cells (CSCs) as rare population of tumor cells, with stem cell characteristics, is responsible for tumor growth, resistance, and recurrence. This hypothesis would propose that indiscriminate killing of cancer cells would not be as effective as selective targeting of the CSCs and that treatment failure is often the result of CSCs escaping traditional therapies. Therefore, development of therapeutic strategies that specifically target on CSCs is critical in reducing the risk of cancer relapse. A lot of plant-derived phytochemicals and plant extract have been shown to be able to target and kill CSCs. Therefore, the use of phytochemicals may be a true therapeutic strategy for eradicating cancer through the elimination of CSCs. Side population (SP) is one of the CSC characteristic that define the cells that express ATP-binding cassette (ABC) drug transporters, so don’t take up chemotherapy drugs. These population are characterized by efflux of fluorescence dye such as Hoechst 33342 and Rhodamin 123. The anticancer activity of Morus .alba leaf extract has been elucidated for a variety of cancer.
In this study, at first the cytotoxic effect of M.alba leaf extract has been investigated against human breast cancer cell lines, MCF7. Furthermore, the final aim of the present study was to investigate the effect of M.alba leaf extract on SP cells as cancer stem (-like) cells in MCF7 cell line.