RESUMO
Collagen type IV in the lamina propria mucosae is one of the main components of the basement membrane of normal and transitional colon mucosa. The aim of the present study was to assess the use of anti-collagen type IV antibodies in the evaluation of biological activity of epithelial tumours of the colon. Formalin-fixed and paraffin-embedded specimens of polyps and carcinomas of the colon from 14 patients were analyzed. In transitional mucosa around epithelial tumours, only minor deformities of the evenly thick collagen type IV-containing basement membranes were found. This pattern was different in polyps where collagen type IV-positive basement membrane components extended between basolateral membranes of epithelial cells. Local changes of collagen type IV positivity in basement membranes of polyps were observed. Positivity of epithelial basement membranes disappeared in adenocarcinomas but there was an increased positivity in fibrillar components of stroma. Basement membranes of microvessels in lamina propria mucosae were also positive for collagen type IV. Similar observations were made in the stroma of polyps. Our results indicate that loss of collagen type IV in basement membranes of adenocarcinomas is related to loss of differentiation and the malignant potential of epithelial tumours of colon.
