Warburg Effect Targeting Co(III) Cytotoxin Chaperone Complexes

A glucose-based vector for targeting cancer cells conjugated to a tris­(methylpyridyl)­amine (tpa) ligand to generate targeted chaperone and caging complexes for active anticancer agents is described. The ligand, tpa­(CONHPEGglucose)1, inhibits hexokinase, suggesting that it will be phosphorylated in the cell. A Co­(III) complex incorporating this ligand and coumarin-343 hydroximate (C343ha), [Co­(C343ha)­{tpa­(CONHPEGglucose)1}]­Cl, is shown to exhibit glucose-dependent cellular accumulation in DLD-1 colon cancer cells. Cellular accumulation of [Co­(C343ha)­{tpa­(CONHPEGglucose)1}]+ is slower than for the glucose null and glucosamine analogues, and the glucose complex also exhibits a lower ability to inhibit antiproliferative activity. Distributions of cobalt (X-ray fluorescence) and C343ha (visible light fluorescence) in DLD-1 cancer cell spheroids are consistent with uptake of [Co­(C343ha)­{tpa­(CONHPEGglucose)1}]+ by rapidly dividing cells, followed by release and efflux of C343ha and trapping of the Co­{tpa­(CONHPEGglucose)1} moiety. The Co­{tpa­(CONHPEGglucose)1} moiety is shown to have potential for the caged and targeted delivery of highly toxic anticancer agents.