An immunoperoxidase method was used to compare the distribution of
fibronectin and
laminin between superficially spreading and deeply infiltrating parts of
signet-ring-cell carcinoma of the stomach. In both parts,
laminin-containing basement membranes were generally scarce, but they were observed on some of the
cancer cells which had differentiated to glandular cells. Intramucosal invasion fronts of superficially spreading
cancers often showed a layered structure, consisting of a middle zone of small
cancer cells together with a superficial and a deep zone of signet-ring cells. In this structure, linear
fibronectin and
laminin deposits were common on the
cancer cells in the deep zone, but rare in the superficial zone. However, fibrillar
fibronectin deposits in the stroma were not considerably larger in either zone. At extramucosal invasion fronts of deeply infiltrating (advanced)
cancers, a stromal remodelling with an increased amount of fibrillar
fibronectin deposits was often observed around the
cancer cells, whose cell surface
fibronectin was largely lost even from some basement membranes. These findings suggest that invasive activity of
signet-ring-cell carcinoma may not be related to the mere presence or absence of cell-surface
fibronectin and
laminin but to the amount of stromal
fibronectin, which could reflect a cell-stroma interaction. Signet-ring-cell
carcinomas have a stage of intramucosal growth in which
cancer cells may live in dependence upon the pre-existing stroma and form the layered structure, while in advanced stages
cancer cells seemed to have acquired an ability to elicit their own "
tumor stroma".