EXPRESSION OF FIBRONECTIN AND ITS INTEGRIN RECEPTOR ALPHA-5-BETA-1 INCANINE MAMMARY-TUMORS

Fibronectin and its integrin receptor alpha 5 beta 1 were studied by i mmunohistochemical methods in five normal canine mammary glands, four dysplastic glands and 18 mammary tumours. The aim of the study was to evaluate the possible changes in the alpha 5 beta 1 integrin receptor and its ligand fibronectin in relation to the metastatic capacity of c anine mammary neoplasms. The immunostaining of alpha 5 beta 1 was very uniform in the hyperplastic glands but uneven in the mammary tumours. The expression of alpha 5 and beta 1 was diminished in metastatic tum ours but there were some alpha 5-positive cells with pronounced featur es of malignancy and immaturity. Stromal fibronectin was increased in most cases and cytoplasmic staining of fibronectin was observed in epi thelial and myoepithelial cells in mammary neoplasms but not in normal or dysplastic mammary tissue. There was no relationship between the c ontent of alpha 5 beta 1 and the expression of fibronectin in canine m ammary tumours.