Box 1.
ALDH+ and CD24−CD44+ are different markers for breast cancer stem cells (BCSCs) (Liu et al., 2014). CD24−CD44+ marks BCSCs in a mesenchymal-like (EMT) state, primarily quiescent, and localized at the tumor invasion front; ALDH+ marked BCSCs with epithelial-like (MET) state, proliferative, and localized at the tumor center. They both can self-renew and differentiate. The tumorigenesis ability of BCSCs in the overlap of ALDH+ and CD24−CD44+ is the highest. These two types of BCSCs can reciprocally transform, which could be induced by tumor microenvironmental factors, microRNAs, lncRNAs or epigenetic proteins. |