Tumor angiogenesis and the cancer stem cell model

Abstract

In recent years, research and interest in the area of cancer stem cells has grown tremendously. An increasing number of studies are finding that many different cancers contain a subpopulation of tumor cells that display several defining characteristics of adult tissue stem cells, including multipotent differentiation potential, long-term self-renewal capacity, and the expression of various molecular markers of stemness. Most importantly, these stem-like cancer cells also appear to possess the strongest tumorinitiating potential of all the cells in the tumor, a finding that has led to the development of the cancer stem cell model for tumor progression. This model suggests that tumors are organized in a developmental hierarchy (similar to a healthy tissue), with longterm tumor progression being driven by a self-renewing tumor stem cell at the top of the hierarchy. As this new model for tumor progression takes shape, researchers are beginning to investigate how cancer stem cells fit into various other aspects of cancer biology. In this regard, several recent studies are uncovering an intriguing relationship between tumor angiogenesis and cancer stem cells. This chapter reviews recent data suggesting that cancer stem cells may play an important role in promoting tumor angiogenesis, and that tumor vasculature may in turn have a role in supporting and maintaining cancer stem cells. Related work suggesting that antiangiogenic therapy may be used as a strategy to eliminate the critical CSC population is also discussed. © 2008 Springer US.