Cancer stem cells and niche mircoenvironments.

The isolation and characterization of cancer stem cells as the cells that initiate cancer has lead to a paradigm shift in our approaches toward cancer management. According to this new concept, only a small percentage of cells, termed cancer stem cells (CSCs), drive tumor formation and progression and give rise to the heterogeneity of tumor cells. It has been a decade since the cancer cell was proclaimed to be, self-sufficient in growth signals. However, recent researches suggest that even the CSCs rely heavily on the ancillary cells present in the tumor stroma for their persistence in the quiescent state. In this review we will discuss a complex integrated ongoing process in the tumor microenvironment which enables the CSCs to maintain their undifferentiated yet plastic state.