Cyclic-RGDyC functionalized liposomes for dual-targeting of tumor vasculature and cancer cells in glioblastoma: An in vitro boron neutron capture therapy study

The efficacy of boron neutron capture therapy depends on the selective delivery of B-10 to the target. Integrins alpha v beta 3 are transmembrane receptors over-expressed in both glioblastoma cells and its neovasculature. In this study, a novel approach to dual-target glioblastoma vasculature and tumor cells was investigated. Liposomes (124 nm) were conjugated with a alpha v beta 3 ligand, cyclic arginine-glycine-aspartic acidtyrosine-cysteine peptide (c(RGDyC)-LP) (1% molar ratio) through thiol-maleimide coupling. Expression of alpha v beta 3 in glioblastoma cells (U87) and human umbilical vein endothelial cells (HUVEC), representing tumor angiogenesis, was determined using Western Blotting with other cells as references. The results showed that both U87 and HUVEC had stronger expression of alpha v beta 3 than other cell types, and the degree of cellular uptake of c(RGDyC)- LP correlated with the alpha v beta 3-expression levels of the cells. In contrast, control liposomes without c(RGDyC) showed little cellular uptake, regardless of cell type. In an in vitro boron neutron capture therapy study, the c(RGDyC)- LP containing sodium borocaptate generated more rapid and significant lethal effects to both U87 and HUVEC than the control liposomes and drug solution. Interestingly, neutron irradiated U87 and HUVEC showed different types of subsequent cell death. In conclusion, this study has demonstrated the potential of a new dual-targeting strategy using c(RGDyC)- LP to improve boron neutron capture therapy for glioblastoma.