SUMMARYLectins have been widely used in cell surface studies and in the development of potential anti-cancer drugs. Many past studies that have examined lectin toxicity have only evaluated the effects on cancer cells, not their non-cancer counterparts. In addition, few past studies have evaluated the relationship between lectin-cell binding and lectin toxicity on both cell types. Here we examine these parameters in one study: lectin-cell binding and lectin toxicity with both cancer cells and their normal counterparts. We found that the human colon cancer cell line CCL-220/Colo320DM bound to agarose beads derivatized with Phaseolus vulgaris agglutinin (PHA-L) and wheat germ agglutinin (WGA), while the non-cancer human colon cell line CRL-1459/CCD-18Co did not. When these lectins were tested for their effects on cell viability in culture, both cell lines were affected by the lectins but at 6, 48 and 72 hours incubation times, PHA-L was most toxic to the cancer cell line in a concentration dependent manner. At 48 hours incubation, WGA was more toxic to the cancer cell line. The results suggest that it may be possible to develop lectin protocols that selectively target cancer cells for death. In any case, examination of both malignant cells and their non-malignant counterparts, analysis of their binding characteristics to immobilized lectins, and examination of the toxicity of free lectins in culture, provides a multiparameter model for obtaining more comprehensive information than from more limited approaches. KeywordsImmobilized lectin binding; lectin toxicity in culture; human colon cancer and non-cancer colon cells; PHA-L; WGA

SummaryThis laboratory has developed and used a novel histochemical assay using derivatized agarose beads for over a decade to examine the surface properties of various cell types. Most recently we have used this assay to examine lectin binding ligands on two human cell types, CCL-220, a colon cancer cell line, and CRL-1459, a non-cancer colon cell line. We found that CCL-220 cells bound specific lectins better than CRL-1459, and this information was used to test for possible differential toxicity of these lectins in culture, as a possible approach in the design of more specific anti-cancer drugs. Although we have examined the validity of the bead-binding assay in sea urchin cell systems, we have not validated this technique for mammalian cells. Here the binding results of the bead assay are compared with conventional fluorescence assays, using lectins from 3 species (Triticum vulgaris, Phaseolus vulgaris, and Lens culinaris) on the 2 colon cell lines. These lectins were chosen because they seemed to interact with the two cell lines differently.Binding results obtained using both assays were compared for frozen, thawed and fixed; cultured and fixed; and live cells. Both qualitative and quantitative fluorescence results generally correlated with those using the bead assay. Similar results were also obtained with all of the 3 different cell preparation protocols. The fluorescence assay was able to detect lower lectin binding ligand levels than the bead assay, while the bead assay, because it can so rapidly detect cells with large numbers of lectin binding ligands, is ideal for initial screening studies that seek to identify cells that are rich in surface binders for specific molecules. The direct use of frozen, thawed, and fixed cells allows rapid mass screening for surface molecules, without the requirement for costly and time consuming cell culture.

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