Carbohydrate Dependent Targeting of Cancer Cells by Bleomycin−Microbubble Conjugates

Biotinylated bleomycin A(5) was attached to streptavidin-derivatized microbubbles, and a solution containing the conjugate was passed over a monolayer of cultured MCF-7 cells. The bleomycin-derivatized microbubbles adhered to the MCF-7 cells, and the association could be monitored by the use of a microscope. Three other cancer cell lines gave similar results. The bleomycin-microbubble conjugate did not bind to a normal breast cell line (MCF-10A) or to the matched noncancer cell lines corresponding to the other cancer cell lines targeted by bleomycin. No binding to any tested cell line was observed when the microbubbles lacked conjugated bleomycin A(5) or when the microbubble contained a bleomycin A(5) analogue lacking the carbohydrate moiety.