Targeting the cubilin receptor through the vitamin B12 uptake pathway: Cytotoxicity and mechanistic insight through fluorescent Re(I) delivery

Abstract

The intrinsic factor (IF) vitamin B12 ileum anchored receptor, cubilin, mediates endocytotic uptake of the IF complex of vitamin B12 to the blood serum. This receptor was targeted for the selective delivery and accumulation of a new bioprobe, a B12 conjugate of rhenium 2, in the cubilin expressing placental choriocarcinoma BeWo cell line. Competitive uptake and cytotoxicity assays of 2 were investigated and interactions with nuclear DNA explored. In addition, the mechanism of internalization of 2 was confirmed to proceed in an IF-cubilin mediated fashion via siRNA transfection experiments. These studies show the great potential of cubilin as a new target for the delivery of B12 based conjugates for cancer diagnostics and/or treatment. © 2009 American Chemical Society.