VITRONECTIN IN COLORECTAL ADENOCARCINOMA - SYNTHESIS BY STROMAL CELLSIN CULTURE

We have investigated the expression and cellular source of vitronectin in colorectal adenocarcinoma. Immunofluorescence staining of tissue s ections revealed the presence of vitronectin in the stroma of the 11 t umors studied, but not in adjacent normal colon. A method was devised for the isolation from colorectal adenocarcinomas of fibroblast-like e els that stained positive for vimentin but negative for cytokeratin. T hese tumor-derived stromal cells synthesized and secreted vitronectin, as revealed by metabolic labeling and immunoprecipitation. This was c onfirmed by Southern blot analysis of polymerase chain reaction amplif ication products from reverse-transcribed RNA. Normal skin fibroblasts did not synthesize vitronectin. Immunofluorescence staining showed vi tronectin deposited at focal contact sites in the tumor-derived cells, where it colocalized with vinculin and the alpha(v) integrin subunit. The deposition of vitronectin into focal contact sites was not depend ent on the presence of serum. The finding that vitronectin can be synt hesized and secreted by tumor-derived fibroblast-like cells in culture indicates that vitronectin expression can be promoted by as yet unkno wn signals provided in disease states, such as cancer. (C) 1994 Academ ic Press,Inc.