Integrin targeting of glyphosate and its cell adhesion modulation effects on osteoblastic MC3T3-E1 cells revealed by label-free optical biosensing

This study is a discovery of interesting and far reaching properties of the world leading herbicide active ingredient glyphosate. Here we demonstrate the cell adhesion-modifying characteristics of glyphosate affecting cellular interactions via Arg-Gly-Asp (RGD)-dependent integrins. This conclusion was supported by the observations that a glyphosate surface coating induced integrin-specific cell adhesion, while glyphosate in solution inhibited cell adhesion on an RGD-displaying surface. A sensitive, real-time, label-free, whole cell approach was used to monitor the cell adhesion kinetic processes with excellent data quality. The half maximal inhibitory concentration (IC50) for glyphosate was determined to be 0.47 +/- 0.07% (20.6 mM) in serum-free conditions. A three-dimensional dissociation constant of 0.352 mM was calculated for the binding between RGD-specific integrins in intact MC3T3-E1 cells and soluble glyphosate by measuring its competition for RGD-motifs binding, while the affinity of those RGD-specific integrins to the RGD-motifs was 5.97 mu M. The integrin-targeted affinity of glyphosate was proven using competitive binding assays to recombinant receptor av beta 3. The present study shows not only ligand-binding properties of glyphosate, but also illustrates its remarkable biomimetic power in the case of cell adhesion.