title: In situ expression of beta 1, beta 3 and beta 4 integrin subunits in non-neoplastic endothelium and vascular tumours.
abstract: Endothelial cells play an important role in adhesive interactions between circulating cells and extracellular matrix proteins. In vitro studies have shown that many of these processes are mediated by a superfamily of alpha beta heterodimeric transmembrane glycoproteins called integrins. The distribution patterns of beta 1, beta 3 and beta 4 integrin subunits in endothelial cells (EC) in situ were examined immunohistochemically on serial frozen sections of a wide range of non-neoplastic tissues and of vascular tumours, both benign and malignant. Expression of the beta 1 subunit was a constitutive feature of EC. Among the beta 1-associated alpha subunits, alpha 5 and alpha 6 were broadly distributed in EC, irrespective of vessel size and microenvironment. The alpha 3 subunit displayed intermediate levels of expression with a slight preference for small vessel EC. Presence of alpha 1 was confined to EC of capillaries and venules/small veins. Expression of alpha 2 in EC was inconsistent. With rare exceptions, the alpha 4 chain was absent in EC. The beta 3 and alpha v subunits were expressed in most EC, though not always concomitantly. In contrast to the beta 1 chain, however, these integrin subunits were absent in EC of glomerular capillaries and were expressed variably in sinusoidal EC. The beta 4 chain was evenly present in the great majority of EC, except for those of large vessels. In vascular tumours, the patterns of beta 1 and alpha 1 to alpha 6 subunit expression generally corresponded to those found in their non-neoplastic counterparts. Expression of beta 3, alpha v and beta 4 chains, however, decreased in neoplasia, especially in angiosarcomas. These data show that EC dispose of broad and at the same time differential repertoires of integrin subunits that presumably reflect vessel-type associated functional differences among these cells. In vascular tumours, the orthologous distribution patterns of beta 1 and alpha 1 to alpha 6 chains are conserved in most instances while the amounts of beta 3, alpha v and beta 4 subunits expressed in EC tend to decrease in the course of malignant transformation.
authors.affiliation: Institute of Pathology, University of Heidelberg, Germany.
authors.forename: G
authors.initials: G
authors.lastname: Mechtersheimer
authors.forename: T
authors.initials: T
authors.lastname: Barth
authors.forename: W
authors.initials: W
authors.lastname: Hartschuh
authors.forename: T
authors.initials: T
authors.lastname: Lehnert
authors.forename: P
authors.initials: P
authors.lastname: Möller
mesh_terms: D000911:Antibodies, Monoclonal; D001160:Arterioles; D002196:Capillaries; D002540:Cerebral Cortex / Q000098:blood supply; D004730:Endothelium, Vascular / Q000166:cytology / Q000378:metabolism* / Q000473:pathology; D005918:Glomus Tumor / Q000378:metabolism / Q000473:pathology*; D006391:Hemangioma / Q000378:metabolism / Q000473:pathology*; D006392:Hemangioma, Cavernous / Q000378:metabolism / Q000473:pathology; D006394:Hemangiosarcoma / Q000378:metabolism / Q000473:pathology*; D006801:Humans; D007150:Immunohistochemistry; D019012:Integrin beta1; D039661:Integrin beta3; D039663:Integrin beta4; D016023:Integrins / Q000032:analysis / Q000096:biosynthesis*; D009928:Organ Specificity; D014699:Venules
chemical_list: D000911:Antibodies, Monoclonal; D019012:Integrin beta1; D039661:Integrin beta3; D039663:Integrin beta4; D016023:Integrins