Unconventional approach to direct targeting of breast cancer cells

A superior mechanism of detecting cancerous cells and delivering anti-cancer drugs to highly localized targets is currently lacking in the field of oncology. Unfortunately, chemotherapy is not a specialized method of delivering therapeutic reagents to the body, and is therefore toxic to cancerous and noncancerous cells alike. For this reason, it is imperative to seek alternative forms of treatment. Lectins, for example, act as the ideal'bait' because they exhibit a high affinity towards carbohydrate-rich cellular surfaces. Transformed cells have altered surfaces that often express elevated levels of glycoprotein than do healthy cells, and readily bind to lectins. Unlike older lectin assays that are be costly and require fresh, robust cells with no guarantee of actually producing any viable results, our lab has developed a derivatized bead assay that allows for the rapid screening of cell surface markers. This assay involves the use of beads that are derivatized with over a hundred different molecules including various proteins other than only lectins, amino acids, and sugars, that will bind to carbohydrate-rich molecules in seconds to allow for rapid screening of various cell surface markers. Clustering or binding of these lectins to their preferred target cells helps differentiate between cancerous and noncancerous cell lines. Furthermore, characterization of these cells will help determine specific surface markers that are unique for each type of cell. In this study, we test the efficacy of the lectin-bead assay in distinguishing cancerous (HTB-126) and healthy (HTB-125) breast cells from the same patient. Each cell line was cultured and subjected to the bead assay using beads derivatized with the following lectins: Wheat germ agglutinin (WGA), Lens culinaris agglutinin (LCA), Concanavalin A (ConA), and Poly L-lysine (PL) - an adhesive reagent rather than a lectin. Cell binding affinity to each lectin bead was also tested in the presence or absence of haptenic/nonhaptenic sugars. In order to determine cell viability in the presence of these lectins, each cell line was exposed to free lectins of different concentrations over 6, 12, 24, and 48 hour incubation periods. An MTT (3-(4,5-Dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide, a tetrazole) assay was performed to measure toxicity levels for each experimental group. Histochemical results using the derivatized bead assay indicated that WGA and LCA preferentially bound to cancerous cell lines only, while ConA did not distinguish between cancerous and noncancerous cell lines. The cell viability assay suggested that WGA is a toxic inhibitor of cell proliferation for both HTB-126 and HTB-125 on a concentration-dependent basis. ConA reduced cell viability to a lesser degree than WGA, while LCA did not prove to be significantly detrimental to either cell line. The major significance of these results is that the lectin bead assay can distinguish cancer from non-cancer breast cells depending on the type of lectin used. In addition, the ability of free lectins to kill cells in culture may offer a new approach in the development of more specific anti-cancer drug