Improving the Properties of Techentium-99m Labeled Angiogenesis Antagonist Polypeptide for the Detection of Breast Cancer by Eternal Imaging
Annual rept. 1 Jun 2000-31 May 2001
MASSACHUSETTS UNIV MEDICAL CENTER WORCESTER
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The polypeptide RGD-4C has been shown to localize preferentially on integrins at sites of tumor angiogeneisis. The terminal amines of both RGD-4C and RGE-4C peptides were conjugated with NHS-HYNIC and radiolabeled with Tc-99m using tricine. Studies in tissue culture were conducted with human umbilical vein endothelial cells HUVE. Successful radiolabeling of both the RGD-4C and RGE-4C was confirmed by RP and SE HPLC at specific radioactivity of 18 - 20 C1mu-mol. Both Tc-99m complexes were stable. At 1 hr, 4 deg C and at nM concentrations, the cell accumulation of Tc-99m RGD-4C peptide was as much as 16 times greater than the control RGE-4C. As a check, 50 nM of unlabeled RGD-4C blocked 50 of the binding of Tc-99m labeled RGD-4C. As determined by SE HPLC, the binding of Tc-99m labeled RGD-4C to purified Alphasub vBeta3 integrin protein was 6.8 fold higher than that of Tc-99m labeled RGE-4C. Conclusion we have shown that a Tc-99m labeled cyclic RGD-4C peptide shows high selectivity for Alphasub vBeta3 integrin-expressing cells in vitro.
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