Experimental Cell Research 182 (1989) 144-151 Enhanced Binding of Fibronectin-Coated Latex Beads to Quiescent 3T3-Ll Ceils Is Correlated with Escape from Growth Arrest YOSHIKI SHIBA,*,’ YASUTO SASAKI,* YOSHINOBU KANNO,* and FREDERICK GRINNELL? *Department of Oral Physiology, Hiroshima University School of Dentistry, Hiroshima 734, Japan, and TDepartment of Cell Biology and Anatomy, The University of Texas Southwestern Medical School at Dallas, Dallas, Texas 75235 The possible involvement of fibronectin receptors in growth stimulation was investigated by an analysis of fibronectin-coated latex bead binding to 3T3-Ll cells under various conditions. 3T3-Ll cells, growth-arrested in a medium with a low concentration of calf serum, bound few fibronectin-coated beads. After addition of serum at concentrations of 1.O% or higher, there was a rapid and transient increase in the number of cells with bound beads and a subsequent increase in the incorporation of bromodeoxyuridine (BrdU) into cell nuclei. Incorporation of BrdU was observed in about 60% of the cells with bound beads. Fibroblast growth factor and platelet-derived growth factor at concentrations of 5 rig/ml or higher also enhanced binding of fibronectin-coated beads to cells. Stimulation of bead binding by epidermal growth factor and insulin was weak. Fibroblast growth factor, but not epidermal growth factor, increased the incorporation of BrdU into nuclei. These results indicate a relationship between stimulation of cell proliferation in quiescent cells and increased binding by cells of fibronectin-coated latex beads. 6 1989 Academic PIES, IN. Cell adhesion by fibroblasts to ftbronectin is mediated by specific cell-surface fibronectin receptors [l-3]. Localization of these receptors has been achieved visually by the binding of latex beads coated with fibronectin [4-6]. The tumor promoter 12-O-tetradecanoylphorbol-13-acetate (TPA) enhances both the binding of latex beads coated with fibronectin to the apical cell surfaces of 3T3-Ll cells and the proliferation of cells in the presence of a low concentration of calf serum [7]. In addition, TPA also stimulates the proliferation of various types of cultured cells [g-lo]. Enhancement of cell proliferation by TPA appears to be associated with the modulation of the fibronectin receptor. Some growth factors also stimu- late the proliferation of cells and modulate the secretion of fibronectin [l 11, and the expression of fibronectin is closely related to the progression of the cell cycle [12]. It still remains, however, to be determined whether the modulation of tibronectin receptors is related to control of cell proliferation. It has been suggested that cell adhesion regulates cell proliferation, because proliferation of fibroblasts requires the adequate attachment of cells to a substra- tum, such as glass, plastic, or collagen, and transformation abolishes this require- ment [13, 141. Cell differentiation also is modulated by substrata such as collagen and flbronectin [15, 161, Some information about the substratum may be commu- ’ To whom reprint requests should be addressed. Copyright @ 1989 by Academic Fess, Inc. All ri&hts of reproduction in any form reserved 0014-4827/89 $03.00 144