Localization of vitronectin- and fibronectin-receptors on cultured human glioma cells.

Utilizing a human astrocyte-derived glioma cell line, we have demonstrated the presence of a vitronectin receptor, alpha v beta 3, and a fibronectin receptor, alpha 5 beta 1, on the surface of the cells spreading on the respective adhesion molecules by immunohistochemical analyses. By phase-contrast microscopy, these receptors were found to be expressed predominantly in the focal contact-like area, suggesting that they were involved in the spreading of the cells upon contact with these adhesion molecules. Interestingly, they appeared to have differential functions and roles as integrins as evidenced by different time-dependent distribution profiles on the cell surface in the serum-containing medium. Furthermore, both vitronectin and fibronectin seem to have chemotactic effects onto the glioma cells as observed in a Boyden chamber study. Although these receptors are not expected to be present on the surface of astrocytes under physiological conditions, they may be expressed thereon and involved in gliosis when the cerebral vasculature is traumatized and, thereby, blood proteins, including vitronectin and fibronectin, come into contact with the astrocytes.