Abstract
The anti-angiogenic agent, diamino propane tetraiodothyroacetic acid (DAT), is a thyro-integrin (integrin αvβ3) antagonist anticancer agent that works via genetic and nongenetic actions. Tetraiodothyroacetic acid (tetrac) and DAT as thyroid hormone derivatives influence gene expression after they transport across cellular membranes. To restrict the action of DAT to the integrin αvβ3 receptors on the cell surface, we used DAT-conjugated PLGA nanoparticles (NDAT) in an active targeting mode to bind to these receptors. Preparation and characterization of NDAT is described, and both in vitro and in vivo experiments were done to compare DAT to NDAT. Intracellular uptake and distribution of DAT and NDAT in U87 glioblastoma cells were evaluated using confocal microscopy and showed that DAT reached the nucleus, but NDAT was restricted from the nucleus. Pharmacokinetic studies using LC-MS/MS analysis in male C57BL/6 mice showed that administration of NDAT improved the area under the drug concentration curve AUC(0-48 h) by 4-fold at a dose of 3 mg/kg when compared with DAT, and Cmax of NDAT (4363 ng/mL) was 8-fold greater than that of DAT (548 ng/mL). Biodistribution studies in the mice showed that the concentrations of NDAT were higher than DAT/Cremophor EL micelles in heart, lung, liver, spleen, and kidney. In another mouse model using female NCr nude homozygous mice with U87 xenografts, tumor growth was significantly decreased at doses of 1 and 3 mg/kg of NDAT. In the chick chorioallantoic membrane (CAM) assay used to measure angiogenesis, DAT (500 ng/CAM) resulted in 48% inhibition of angiogenesis levels. In comparison, NDAT at low dose (50 ng/CAM) showed 45% inhibition of angiogenesis levels. Our investigation of NDAT bridges the study of polymeric nanoparticles and anti-angiogenic agents and offers new insight for the rational design of anti-angiogenic agents.