A LARGE CELL-ADHESIVE SCATTER FACTOR SECRETED BY HUMAN GASTRIC-CARCINOMA CELLS

Human gastric carcinoma cell line STKM-1 secretes a large protein that induces scattering of a rat liver epithelial cell line (BRL) into dis connected individual cells in monolayer culture. This cell-scattering factor was purified from serum-free conditioned medium of STKM-1 cells and found to be composed of three disulfide-linked subunits of 140, 1 50, and 160 kDa. The 140-kDa peptide contains an amino acid sequence h omologous to that of the laminin B2t chain. The native protein has an apparent molecular mass of >1000 kDa and a pI of 5.0. In addition to t he cell-scattering activity, the purified protein stimulates attachmen t of BRL cells to substrate and their migration. Similar effects have been observed toward various cell lines, including nontumorigenic epit helial, endothelial, and fibroblastic cell lines and human cancer cell lines. Similar cell-scattering activity was secreted by human squamou s carcinoma and gastric carcinoma cell lines and nontumorigenic epithe lial and endothelial cell lines. These results indicate that the prote in, named ''ladsin,'' is probably an extracellular matrix protein that regulates cell-cell and cell-substrate interactions and cell migratio n.