LECTIN-MEDIATED BIOADHESION - PROTEOLYTIC STABILITY AND BINDING-CHARACTERISTICS OF WHEAT-GERM-AGGLUTININ AND SOLANUM-TUBEROSUM LECTIN ON CACO-2, HT-29 AND HUMAN COLONOCYTES

For the development of lectin-mediated drug delivery systems, the prot eolytic stability of the non-toxic lectins from Arachis hypogea, Lens culinaris, Dolichus biflorus, Solanum tuberosum (STL) and Triticum vul gare was investigated by in vitro exposure to gastrointestine-located enzymes. No degradation products were observed within 24 h of incubati on on sodium dodecyl sulfate polyacrylamide gels. Binding to human col on carcinoma cell lines was investigated by flow cytometry. The fluore scein-labelled derivatives of N-acetylglucosamine-specific wheat germ agglutinin (WGA) and STL exhibited the highest cell-associated fluores cence intensity. As determined by dilution experiments, the number of WGA-binding sites on Caco-2, HT-29 and human colonocytes exceeded thos e for STL by 5-, 1.7- and 1.4-fold, respectively. By a competitive flo w cytometric assay using N,N', N''-triacetylchitotriose for inhibition , WGA-affinity exceeded STL-affinity by ten-fold. The affinity of each lectin to Caco-2, HT-29 and human colonocytes was about the same, ind icating that similar lectin receptors were involved. Preventing N-glyc osylation of the carcinoma cells by pretreatment with 0.001% tunicamyc in for 40 h resulted in 30% inhibition of WGA-and STL-binding. When WG A was covalently attached to Sepharose beads (250-350 mu m), the inter action with HT-29 and Caco-2 cells showed stable and tight binding. Th erefore, especially considering the comparable affinity of human colon ocytes and monolayer-forming Caco-2 and HT-29 cells, this system is pr oposed as a model for the development of lectin-mediated particulate p harmaceutical devices. (C) 1997 Elsevier Science B.V.