Preparation and Evaluation of New LAT1-Targeted USPION to Improve Sensitivity and Specificity in Metabolic Magnetic Imaging of Breast Cancer

Abstract

The purpose of this study was the investigation of the targeting potential of tyrosine-conjugated ultra small superparamagnetic iron oxide nanoparticles (USPIONs) as a new targeted nano-contrast agent for application in molecular magnetic resonance imaging (MRI) of breast cancer. Recently, studies demonstrated that L-type amino acid transporters (LAT1) are highly expressed in breast cancer cells. Thus, LAT1 targeting via tyrosine as a LAT1 substrate could improve the sensitivity and specificity of this nanosized contrast agent. To achieve this goal, USPIONs were conjugated to tyrosine and characterized using DLS and FT-IR. The cell viability was measured in different concentrations of nanoparticles (0.6, 1.2, 2.4mM) in breast cancer cells (MDA231, MCF7,4T1) and control cell line (normal kidney cells; HEK293) with the MTT assay. Cellular uptake was evaluated via Prussian blue staining and Inductively Coupled Plasma-Optical Emission Spectroscopy (ICP-OES) as well as by measurement of the reduction of signal intensity using 3Tesla clinical MRI. T2-weighted imaging in tumor-bearing bulb/c mice was performed via brain coil and home-built phantom. The particle size and charge of USPIO significantly changed after the conjugation of tyrosine. According to ICP-OES results from the cellular uptake of tyrosine-USPION in 4T1 cell line and HEK-293was 48.14%±1.43, and 6.91±0.21, respectively. The reduction in MRI signal intensity at in vitro studies was higher in the presence of tyrosine-USPION than of USPION. The reduction in MRI signal intensity at in vivo studies was 58.83% in the presence of tyrosine conjugated USPION compared with plain nanoparticles. Biodistribution studies demonstrated that the accumulation of tyrosine-USPIONs was about seven times higher than that of non-targeted USPIONs after 24h. In conclusion, tyrosine-USPIO as a new LAT1 targeted contrast agent with high sensitivity and specificity can be suggested as a good and ideal candidate in breast cancer molecular imaging.