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Abstract

Traditional cancer therapy generally leads to harmful side effects, thus warranting development of targeted therapies, which are better tolerated by cancer patients. Our goal is to develop in vivo non-invasive optical imaging assays for optimization of anticancer drug targeted therapy. We have established a fluorescence lifetime F�¶rster Resonance Energy Transfer (FL-FRET) non-invasive whole-body in vivo tomographic imaging technique that can discriminate bound and internalized near-infrared (NIR)-labeled transferrin (Tfn) from free, soluble NIR-Tfn. This FRET-based assay exploits the homodimeric nature of transferrin receptor (TFR) that binds two molecules of Tfn in close proximity to determine dimerization and internalization of TFR-Tfn complexes into cancer cells. The Tfn FRET assay has been validated in vitro by visible and NIRFRET microscopy. FL-FRET tomographic imaging in vivo has been used to measure the internalization of tail-vein injected NIR-Tfn into human breast T47D tumor xenografts in live nude mice. Quantification of FRET donor % (FD%) in T47D tumor xenografts in vivo, indicates a higher proportion of FD% with increasing acceptor:donor ratio, demonstrating tumor uptake of NIR-Tfn. Tfn uptake concentration curve shows high sensitivity of FL-FRET imaging using NIR-Tfn as low as 10�¼g/ml of blood. Furthermore, relative high FD% for holo-Tfn (iron-loaded) compared to that of apo-Tfn (iron-depleted) demonstrates specific TFR-mediated uptake of holo-Tfn by T47D tumor xenografts, as expected since irondepleted apo-Tfn shows reduced binding affinity towards TFR. In conclusion, we have successfully demonstrated the quantitative receptor-mediated uptake of Tfn into human breast tumors in vivo using a novel non-invasive NIR FL-FRET tomographic imaging assay.

Biography

Margarida Barroso is an Associate Professor at the Center for Cardiovascular Sciences, Albany Medical College in Albany, NY. She received her PhD, in Genetics from the University of Lisbon/Gulbenkian Institute of Sciences in Portugal and was a Post-doctoral fellow at the Department of Molecular Biology, Princeton University. She is in a faculty instructor in several international imaging courses and has two issued patents on FRET imaging technology. She belongs to the following scientific societies: American Society of Cell Biology (ASCB), Biophysical Society, Histochemical Society, and Sigma Xi. Since 2008, she is a member of the governing Council of the Histochemical Society. She has published more than 25 papers in reputed journals and acts as a reviewer for several internationally recognized journals.

Email: BarrosM@mail.amc.edu