Embryonic signature in breast cancers; Pluripotency roots of cancer stem cells.

Drug discovery programs for preclinical oncology typically select compounds which have a predilection for inducing cytotoxic effects in cancer cell lines and subsequently, for inhibiting the growth of the transplanted cancer cells in vivo (Winquist et al., 2010). Unfortunately, the cytotoxic effect in vitro and inhibition of tumor growth in animal models are not the end story for curing cancer in preclinical models. The reason behind that is the exciting of small sub type of cells that are relatively resistance to therapy and able to repopulate in vivo, called cancer stem cells (CSCs). O leis et al. recently reported that the pluripotency gene Sox2 but not Oct4 or Nanog is expressed in early stage of breast tumor. Furthermore, the authors demonstrated that Sox2 downregulation, inhibited mammosphere formation and delayed tumor formation in xenograft tumor initiation models (Leis et al., 2012). In this review, we will shed the light on the importance of Sox2 in breast and other tissue tumorigenesis and associated aggressiveness.