In Vitro and In Vivo Imaging of Prostate Cancer Angiogenesis Using Anti-Vascular Endothelial Growth Factor Receptor 2 Antibody-Conjugated Quantum Dot

OBJECTIVE: Authors aimed to determine the targeting ability of vascular endothelial growth factor receptor 2 (VEGFR2)-conjugated quantum dots (QDs) in vitro, and apply it for a xenograft prostate cancer mouse model. MATERIALS AND METHODS: Conjugation reaction of QDs was performed by using the N-(3-dimethylaminopropyl)-N'-ethylcarbodiimide (EDC) and sulfo-(N-hydroxysulfosuccinimide) (Sulfo-NHS). The human umbilical vein cord endothelial cells (HUVECs) were incubated with QDs, conjugated with antiVGFR2, to see a specific binding in vitro. Fluorescent cell images were taken by a confocal microscope. The human prostate cancer cells (PC3) were injected to five nude mice on hind limbs to make the xenograft tumor model. QD-antiVEGFR2 antibody complex was injected into the tumor model and fluorescence measurements were performed at 1, 4, 9, 12, 15, and 24 hours after the injection. RESULTS: The specific interaction between HUVECs and QD-antiVEGFR2 antibody was clearly shown in vitro. The in vivo fluorescence image disclosed that there was an increased signal of tumor, 12 hours after the injection of QDs. CONCLUSION: By showing endothelial cells binding with QDs-antiVEGFR2 antibodyand an experimental application of the antibody for VEGFR2 imaging in the prostate cancer xenograft mouse model, we suggests that the antibody-conjugated QDs can be a potential imaging tool for angiogenesis of the cancer.

Further Studies on Effects of Some Local Anesthetics on Calcium Binding to Lipid-extracted RBC Membrane Fragments: Effect of Modification of Carboxyl Group with Carbodiimide

The interaction of calcium and local anesthetics was investigated with the lipid extracted human RBC membrane fragments treated with carbodiimide in order to titrate carboxyl groups. A water soluble carbodiimide [1-cyclohexyl-3-(2-morpholinoethyl) carbodiimide methotoluene-p-sulfonate], referred to as a carbodiimide reagent, and glycine methylester were used for this purpose. About 76% of carboxyl groups of the fragments were modified at a concentration of 0.05M carbodiimide reagent. The interaction of calcium and local anesthetics such as procaine and lidocaine with these fragments still showed typical competition. However, when the calcium binding was decreased to 8% at a higher concentration of carbodiimide reagent (0.08M), the local anesthetics still inhibited the calcium binding, but were not competitive in nature. In other words, if concentrations of the carbodiimide reagent were raised, the degree of inhibition by the local anesthetics was gradually decreased and was not competitive in nature. Finally, no inhibition was demonstrated when the concentration of the reagent was 0.1 to 0.4M. The above findings, seem to suggest that local anesthetics such as procaine and lidocaine interact with carboxyl groups, in addition to phosphodiester groups of phospholipids as previously reported, and inhibited competitively calcium binding to carboxyl groups of the membrane fragments.

Further Studies on Effects of Some Local Anesthetics on Calcium Binding to Lipid-extracted RBC Membrane Fragments: Effect of Modification of Carboxyl Group with Carbodiimide

The interaction of calcium and local anesthetics was investigated with the lipid extracted human RBC membrane fragments treated with carbodiimide in order to titrate carboxyl groups. A water soluble carbodiimide [1-cyclohexyl-3-(2-morpholinoethyl) carbodiimide methotoluene-p-sulfonate], referred to as a carbodiimide reagent, and glycine methylester were used for this purpose. About 76% of carboxyl groups of the fragments were modified at a concentration of 0.05M carbodiimide reagent. The interaction of calcium and local anesthetics such as procaine and lidocaine with these fragments still showed typical competition. However, when the calcium binding was decreased to 8% at a higher concentration of carbodiimide reagent (0.08M), the local anesthetics still inhibited the calcium binding, but were not competitive in nature. In other words, if concentrations of the carbodiimide reagent were raised, the degree of inhibition by the local anesthetics was gradually decreased and was not competitive in nature. Finally, no inhibition was demonstrated when the concentration of the reagent was 0.1 to 0.4M. The above findings, seem to suggest that local anesthetics such as procaine and lidocaine interact with carboxyl groups, in addition to phosphodiester groups of phospholipids as previously reported, and inhibited competitively calcium binding to carboxyl groups of the membrane fragments.