Characterization of integrin chains in normal and neoplastic human pancreas

Integrins are a complex family of non-covalently linked heterodimeric glycoproteins which function as cell adhesion molecules, interacting with extracellular matrix molecules such as laminin, fibronectin, vitronectin, and collagen, and also having a role in intercellular adhesion. Each integrin subfamily is characterized by a common ß chain associated with variable alpha chains. We have examined, using immunohistological methods, the expression of the VLA (very late activation) family comprising ß1 in association with alpha1-6, and also alpha6 in association with ß4, the LFA ß chain ß2, and the vitronectin receptor, in association with ß1 or ß5 and as the complex alphavß3. Cryostat sections of normal pancreas, pancreatic adenocarcinomas, and ampullary tumours were studied together with six pancreatic carcinoma cell lines. Normal pancreas showed expression of ß1 in all parenchyma. alpha2 and alpah6 had a similar distribution whereas alpha3 expression was confined to ducts, including the very smallest radicles. Staining along the basement membranes of ducts was seen with ß4 and the anti-vitronectin alphav chain receptor antibody 13C2. Islet cells failed to stain with any antibody. No staining of epithelial components was seen with antibodies to alpha1, alpha4, alpha5, or to the alphavß3 form of the vitronectin receptor (ß3 and alphavß3 using the antibody 23C6). Pancreatic adenocarcinomas and ampullary tumours showed expression of alpha2, alpha3, alpha6, ß1, ß4, and the vitronectin receptor (alphav associated with ß1 or ß5).(ABSTRACT TRUNCATED AT 250 WORDS)