Age‐dependent variations of human and rat colon myofibroblasts in culture: Influence on their functional interactions with colon cancer cells

Epithelial–mesenchymal interactions play a pivotal role in colon cancer invasion and metastasis. We aimed at elucidating the impact of long‐term cultivation on the phenotypic and functional characteristics of primary fibroblasts and their interaction with the human colon adenocarcinoma cell line LoVoC5. We used fibroblasts from human colon tumor tissue, normal human colon mucosa, rat normal colon and 2 rat colon‐derived myofibroblast cell lines, MIC316 and MG. The following parameters were studied: cell shape and size, growth curve, intermediate filament expression and extracellular matrix synthesis. Coculture models with or without cell contacts were used to test the effects on LoVoC5 cell proliferation, spreading and adhesion. Irrespective of their origin, fibroblastic cells in primary cultures presented marked phenotypic and functional changes with time. Before passage 5, they presented as large, slow‐growing cells expressing vimentin and α‐smooth muscle actin; synthesizing laminin‐1, fibronectin and collagens I and IV; and inducing LoVoC5 proliferation, spreading and adhesion. After passage 15, they presented as small, fast‐growing cells inconstantly expressing α‐smooth muscle actin and synthesizing mainly type I collagen. In coculture with or without cell contacts, they inhibited LoVoC5 proliferation and allowed only limited cell spreading and adhesion. Myofibroblastic cell lines presented as large, fast‐growing cells expressing vimentin and α‐smooth muscle actin and synthesizing mainly type I collagen. They had no significant effects on LoVoC5 proliferation, spreading and adhesion. Our results underline the importance of age‐dependent variations in colon mesenchymal cells in culture and for the in vitro study of epithelial–mesenchymal interactions in colon cancer. © 2002 Wiley‐Liss, Inc.