Adi Pais1,
Gunanathan Chidambaram2, Inbal Biton3, Raanan Margalit1,
David Milstein2, Hadassa Degani1
1Biological
Regulation, Weizmann Institute of Science, Rehovot, Israel; 2Organic
Chemistry, Weizmann Institute of Science, Rehovot, Israel; 3Veterinary
Resources, Weizmann Institute of Science, Rehovot, Israel
Molecular imaging of novel contrast agents, targeted to the estrogen receptor (ER), composed of Gd-chelate conjugated to estrogen (EPTA-Gd) or tamoxifen (TPTA-Gd), were investigated in vivo. DCE-MRI, applied in mice bearing human breast cancer tumors showed that EPTA-Gd induced a significantly higher enhancement in MDA-ER-positive tumors than in MDA-ER-negative tumors and muscle tissues, indicating specific binding to ER and heterogeneous ER spatial distribution. In contrast, TPTA-Gd showed high enhancement in muscle tissue and lower and similar enhancement in MDA-ER-positive and negative tumors revealing an unknown interaction with muscle components. In conclusion, EPTA-Gd is a potential molecular imaging probe of ER