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New Imaging Kit for Assessment of Estrogen Receptors with Single Photon Emission Computed Tomography

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Final addendum 15 Feb 2005-14 Aug 2006

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To evaluate the feasibility of using 99mTc-glutamate peptide-estradiol GAP-EDL in imaging estrogen receptor positive ER diseases. Methods 3-Aminoethyl estradiol EDL was conjugated glutamate peptide GAP to yield GAP-EDL. Cellular uptake studies of 99mTc-GAP-EDL were conducted in ER cell lines MCF7 13762 and T47D. To demonstrate whether GAP-EDL increases MAP kinase acbvafion Western blot analysis of GAP-EDL was performed in 13762 cells. Biodistribution was conducted in 13762 breast tumor-bearing rats at 0.5-4 hrs. Each rat was administered 99mTc-GAP-EDL 10 microCifrat 10 microgmlrat iv. Two animal models Rats and rabbits were created to ascertain whether cellular or tumor uptake by 99mTc-GAP-EDL was via an ER-mediated process In tumor model breast tumor-bearing rats were pretreated with diethyistilbestrol DES n3 10 mglkg iv 1 hr prior to receiving 99mTc-GAP-EDL 300 microCilrat iv. In endometriosis model part of rabbit uterine tissue was dissected and grafted in the peritoneal wall. The rabbit was administered with 99mTc-GAP-EDL 1 mCifrabbit iv. Results There was 10-40 decreased uptake in cells treated with DES or tamoxifen compared to untreated 99mTc-GAP-EDL. Western blot analysis showed an ERK112 phosphorylation process with GAP-EDL. Biodistribution studies showed that tumor uptake and tumor-to-muscle count density ratio in 99mTc-GAP-EDL groups were significantly higher than in 99mTc-GAP groups at 4 hrs. In O9mTc-GAP-EDL ROl analysis of images showed that tumor-to muscle ratios were decreased in blocking groups. In endometriosis model the grafted uterine tissue could be visualized by 99mTc-GAP-EDL. Conclusion A new imaging kit for assessment of estrogen receptors with single photon emission computed tomography SPECT was developed. Cellular or tumor uptake of 99mTc-GAP- EDL was via an estrogen receptor-mediated process. 99mTc GAP-EDL is a useful ER imaging agent.

Subject Categories:

  • Anatomy and Physiology
  • Medicine and Medical Research
  • Computer Programming and Software

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