Crosstalk between cancer cells and endothelial cells: implications for tumor progression and intervention

Communication between tumor cells and stromal cells is crucial to tumor development and progression. Fibroblasts and macrophages are the most common stromal cells in the tumor microenvironment. Endothelial cells are another type of stromal cell in the tumor microenvironment required for angiogenesis via interaction with tumor cells. Tumor angiogenesis provides not only oxygen and nutrients for tumor cells but also the necessary anchorage to facilitate tumor metastasis. The present review summarizes studies on the crosstalk between cancer cells and endothelial cells with a focus on implications for tumor progression. The following four categories are discussed in this review: (1) cell-cell communication in tumor microenvironment; (2) induction of metastasis by interaction between cancer cells and endothelial cells; (3) angiogenesis induced by tumor cells; (4) therapeutic strategies targeting adhesion and signaling molecules as well as chemokines. This review provides useful information highlighting the process of cancer aggressiveness affected by the crosstalk between cancer cells and endothelial cells, and suggests therapeutic strategies against tumor progression.