The interaction between wheat germ agglutinin and other plant lectins with prostate cancer cells Du-145.

The bioadhesive properties of fluorescein-labeled plant lectins with different carbohydrate specificities were investigated by flow cytometry at 4 and 37 degrees C using Du-145 prostate cancer cells. At both temperatures the lectin association rate increased following the order: Dolichos biflorus agglutinin (DBA)<peanut agglutinin<Ulex europaeus isoagglutinin I<Lens culinaris agglutinin<Solanum tuberosum lectin << wheat germ agglutinin (WGA), reflecting the glycosylation pattern of Du-145 cells. Both, the BSA-binding capacity of the cells referring to nonspecific binding and inhibition studies using the complementary carbohydrate, assured specificity of the lectin-cell interactions except for DBA. The WGA-association rate of Du-145 cells was dependent on temperature indicative for cellular uptake of membrane-bound WGA. Intracellular enrichment of WGA was confirmed by confocal microscopy. As resulted from experiments in presence of ouabain active transport mechanisms were involved in cellular uptake of WGA. Equilibration of the intracellular pH with monensin pointed to accumulation of intracellular located WGA within acidic compartments of Du-145 cells such as the lysosomes or the trans-Golgi complex. Consequently the interaction of WGA with Du-145 cells at 37 degrees C is a one way process due to immediate active transport of membrane-bound lectin into acidic compartments of prostate cancer cells.