CHEMOTAXIS AND HAPTOTAXIS OF HUMAN-MALIGNANT MESOTHELIOMA CELLS - EFFECTS OF FIBRONECTIN, LAMININ, TYPE-IV COLLAGEN, AND AN AUTOCRINE MOTILITY FACTOR-LIKE SUBSTANCE

A human malignant pleural mesothelioma cell line (STAV) was studied wi th respect to production of the extracellular matrix components lamini n, type IV collagen, and fibronectin, and interactions with these prot eins in vitro. We also analyzed STAV cell serum-free conditioned mediu m with respect to the possible presence of ''autocrine motility factor -like'' substance. Sodium dodecylsulfate-polyacrylamide gel electropho resis of biosynthetically labeled STAV serum-free conditioned medium s howed that STAV cells released several proteins into the medium, inclu ding components with molecular weights of 850,000, 540,000 and 440,000 . Using Western blotting we identified these proteins as laminin, type IV collagen, and fibronectin, respectively. By immunocytochemistry la minin, type IV collagen, and fibronectin were detected as a matrix sur rounding the cells. Plastic culture dishes coated with mug quantities of laminin, type IV collagen, and fibronectin induced attachment and s preading of STAV cells. Laminin, type IV collagen, and fibronectin sti mulated directional (chemotactic) migration of STAV cells in Boyden ch ambers fitted with 8 mum filters. The same cells also migrated to inso luble step gradients of filter-bound extracellular matrix components ( haptotaxis). When STAV serum-free conditioned medium was separated by using fast protein liquid chromatography Superose 6 gel filtration, tw o motility-inducing protein peaks were detected. The first peak contai ned proteins with molecular weight > 220,000 that had both chemotactic and haptotactic properties, while the second peak contained material with apparent molecular weights of approximately 67,000 that had chemo tactic and chemokinetic (random motility) but not haptotactic properti es. Analysis of the M(r) 67,000 material indicated that it was a heat- sensitive and trypsin-digestible protein. The production of both solub le and insoluble extracellular matrix components by human mesothelioma cells and the motile response to these molecules as well as the produ ction of a M(r) 67,000 autocrine motility factor-like substance may be important for the highly invasive motile behavior of this tumor.