[Frontiers in Bioscience E4, 2502-2514, June 1, 2012]

Cancer stem cells and niche mircoenvironments

Debasish Boral1, Daotai Nie1

1Department of Medical Microbiology, Immunology and Cell Biology, Southern Illinois University School of Medicine and Simmons Cancer Institute, Springfield, IL, 62794-9626

TABLE OF CONTENTS

1. Abstract
2. Introduction
3. The cancer stem cell theory
4. Cancer stem cells and their niche microenvironment
5. Composition of the CSC niche
5.1. Cellular elements of the CSC niche
5.1.1. Macrophages and dendritic cells
5.1.2. Fibroblasts
5.1.3. Endothelial cells
5.2. Structural elements of the CSC niche
5.2.1. E-cadherin
6. Signaling pathways in the CSC niche
6.1. Wnt signaling pathway
6.2. Notch signaling pathway
6.3. Transforming growth factor-b (TGF-b) signaling pathway
6.4. Nuclear factor-kappa B (NF-kB) signaling pathway
6.5. Other factors controlling CSC Niche
7. Future directions
8. References

1. ABSTRACT

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.