Liposomes are promising drug's delivery systems due to decreased toxicity of the
liposome-encapsulated drug, but wider clinical application requires their more efficient
tumor targeting with uptake, controlled drug release and higher shelf life. The unique metabolic characteristics of
cancer cells based on higher demand for energy and therefore increased
glucose utilization were exploited in the design of
glucose modified
liposomes (GML) with the aim to provide increased
tumor targeting via
glucose transporters and increased ability of drug delivery into
tumor cells.
Tumor accumulating potential of GML and non-
glucose liposomes (NGL) were investigated on CT26 and LS174T
tumor-bearing mice by simple and reliable radiotracer method using 177Lu as radioactive marker. Both
liposomes, GML and NGL were radiolabeled in high radiolabeling yield, showing high in vitro stability in biological media, as the main prerequisite for the biodistribution studies.
Tumors displayed significantly better accumulation of 177Lu-GML with the maximum uptake 6 h post-injection (5.8 ± 0.2%/g in LS174T
tumor and 5.1 ± 0.5%/g in CT26
tumor), compared to negligible uptake of 177Lu-NGL (0.6 ± 0.1%/g in LS174T
tumor and 0.9 ± 0.2%/g in CT26
tumor). Results of comparative biodistribution studies of 177Lu-NGL and 177Lu-GML indicate that increased accumulation of GML is enabled by
glucose transporters and subsequent endocytosis, resulting in their prolonged retention in
tumor tissues (up to 72 h). Direct radiolabeling of
liposomes with 177Lu may be used not only for biodistribution studies using radiotracking, but also for
cancer treatment.