RT Journal Article SR Electronic T1 99mTc-MAG3-PEG8-c(RGDYK) uptake in melanoma tumor JF Journal of Nuclear Medicine JO J Nucl Med FD Society of Nuclear Medicine SP 1520 OP 1520 VO 52 IS supplement 1 A1 de Oliveira, Erica Aparecida A1 Faintuch, Bluma A1 Fernández Núñez, Eutimio Gustavo A1 Santos, Rafael Pereira A1 da Silva, Natanael A1 Targino, Rose A1 Moro, Ana Maria A1 Smith, Charles YR 2011 UL http://jnm.snmjournals.org/content/52/supplement_1/1520.abstract AB 1520 Objectives Integrin αvβ3 plays a significant role in tumor angiogenesis and is a receptor for the extracellular matrix proteins with the exposed arginine-glycine-aspartic (RGD) tripeptide sequence. This study endeavored the development and biological evaluation of a new integrin receptor radiotracer for tumor detection, nominally cyclo 1-5 (RGDdYK) conjugated with MAG3 and spacer PEG8, radiolabeled with 99mTc. Methods 10μl of a 751.6 μM solution of MAG3-PEG8-c(RGDYK) was labeled with 99mTc using sodium tartrate dissolved in labeling buffer (ammonium bicarbonate, ammonium acetate, ammonium hydroxide) along with stannous chloride solution. Reaction was induced by heating at 100°C for 20 min. Radiochemical evaluation was performed by ITLC and was confirmed by HPLC analysis. Internalization assays of the 99mTc-peptide were performed in melanoma cells (B16F10 and SKMEL28). Biodistribution and images were carried out in Nude mice bearing the same cells 2h post-injection. Blocking studies were also conducted by co-injection of 75.2 nmol of cold RGD. Results Radiochemical purity of the radiotracer was 97.2 ± 0.53 %, with a retention time of 10.92 min in HPLC analysis. Internalization of the radiotracer in SK-MEL-28 and in B16F10 cells was respectively 96.13% and 53.55% after 30 min of incubation and these values remained stable until 120 min. Tumor uptake was remarkably greater for animals bearing SK-MEL-28 cells (7.85 ± 2.34 %ID/g) than for B16F10 cells (1.06 ± 0.19 %ID/g). The tumor was 85% blocked in animals with SK-MEL-28 melanoma. Conclusions 99mTc- MAG3-PEG8-c(RGDYK) is a promising radiotracer for melanoma diagnosis due to its specificity , particularly to human SK-MEL-28 cells. Research Support We want to thank the National Nuclear Energy Commission (CNEN/Brazil) for a postgraduate scholarship support