EFFECTS OF HUMAN FIBROBLASTS ON INVASIVENESS OF ORAL-CANCER CELLS IN-VITRO - ISOLATION OF A CHEMOTACTIC FACTOR FROM HUMAN FIBROBLASTS

Oral fibroblasts stimulated invasion of oral-carcinoma cells into the collagen matrix. The mechanisms of the fibroblast-induced stimulation of invasiveness was further investigated by examining cell motility an d proteolytic activity of tumor cells, using mainly an adenoid-cystic- carcinoma cell line (ACCS) and normal fibroblasts from gingival tissue s. Conditioned medium from the fibroblasts grown in serum-free medium was fractionated on a Superdex 200 pg column, and Peak 1 eluted at 200 to 300 kDa and Peak 2 eluted at 50 to 100 kDa were found to contain d ifferent specific activity. Treatment of ACCS cells with Peak 1 result ed in an increase in the production of proteolytic enzymes. Peak 2 sti mulated both chemotaxis and chemokinesis of ACCS cells. A chemotactic factor was purified from the heparin-unbound fraction of Peak 2 by ani on exchange and hydrophobic chromatography, and was named ''fibroblast -derived motility factor (FDMF)''. At 1 mu g/ml, FDMF stimulated chemo taxis of ACCS cells by 4-fold compared with unstimulated controls. Cha racterization of the physicochemical properties of FDMF suggested that it might be different from any known motility factors, Exposure of AC CS cells to FDMF resulted in reduced amounts of actin stress fiber in the cytoplasm and induction of tyrosine phosphorylation of several cel lular proteins detectable 30 to 60 min after treatment These FDMF-indu ced changes were blocked by pre-treatment either with genistein or wit h pertussis toxin. These findings suggest that POMP may be a novel pro tein which stimulates cell motility via a signaling pathway mediated b y a pertussis-toxin-sensitive G protein and tyrosine phosphorylation. (C) 1996 Wiley-Liss, Inc.