The role of beta 1 integrins in tumors

Members of the beta 1 subfamily of integrins contribute to cell adhesion, cytoskeletal organization and signal transduction processes. In some transformed cell lines and tumors, a correlation has been established between the level of expression of the alpha 5/beta 1 fibronectin receptor and neoplastic behavior. In other instances, normal and neoplastic tissue differ in beta 1 integrin expression or sub-cellular distribution. The level of expression of beta 1 integrins in tumor cells may affect tumor growth properties in several ways, including: (a) effects on anchorage dependence of growth; (b) direct signaling processes; (c) organization of the extracellular matrix and presentation of matrix bound growth factors; (d) effects on the functions of host defense cells. Thus the interplay between integrin expression and tumor behavior is complex and might be viewed as a series of interactive feedback loops rather than in terms of a straightforward cause and effect relationship.