Multifaceted roles of integrins in breast cancer metastasis.

Malignant breast cancer can be a debilitating disease due to metastasis to tissues such as brain or bone. The metastatic process involves the invasion of tumor cells into the adjacent tissue, followed by systemic dissemination and colonization of secondary organs. These processes require interactions between tumor cells and a changing microenvironment, which drive cell proliferation, migration, invasion and colonization, as well as promoting cell survival. The integrin family of cell adhesion receptors has been shown to play a critical role in all of these processes, consistent with their extracellular matrix binding properties. Experiments in cultured epithelial cells and in vivo models have demonstrated that integrins can promote various stages of metastasis by modulating the effects of growth factor receptors, extracellular proteases and chemotactic molecules. Integrins may therefore play a pivotal role in multiple mechanisms of metastasis. As a result, they represent promising targets for effective treatment of metastatic breast cancer.