Transformation and tumor progression are frequently associated with expression of the alpha 3/beta 1 heterodimer in solid tumors.

The ability of tumor cells to interact with the extracellular matrix (ECM) is functionally mediated by a variety of receptor molecules among which the integrins are a well-characterized family of mediators. In this study we have investigated immunohistochemically the in vivo expression of the alpha 3/beta 1 promiscuous receptor for ECM constituents in a variety of human solid malignancies. Although the receptor appears to undergo changes in distribution patterns, its expression is maintained in a high percentage of primary (76%) and metastatic (82%) tumors. Furthermore, the comparative immunohistochemical evaluation of alpha 3/beta 1 and its ligands, in a selected number of tumors of different histotypes, demonstrated that the expression of this integrin correlates with the presence of at least one ligand, either around nests of neoplastic cells or at the epithelial-stromal interface. The highly conserved expression of alpha 3/beta 1 shown in this study suggests that this receptor may play a role in tumor growth at the primary as well as at the metastatic site.