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Development of (99m)Tc-EC-tyrosine for early detection of breast cancer tumor response to the anticancer drug melphalan.
- Source :
-
Academic radiology [Acad Radiol] 2013 Jan; Vol. 20 (1), pp. 41-51. Date of Electronic Publication: 2012 Sep 08. - Publication Year :
- 2013
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Abstract
- Rationale and Objectives: Radiolabeled tyrosine analogues that have been successfully used in tumor imaging accumulate in tumor cells via an upregulated L-type amino acid transporter system. The anticancer drug melphalan is an L-type amino acid transporter substrate. Therefore, radiolabeled tyrosine analogues may have great potential in evaluating treatment responses to melphalan. In this study, a (99m)Tc-labeled tyrosine analogue, (99m)Tc tyrosine using N,N'-ethylene-di-L-cysteine (EC) as a chelator, was developed and its potential for noninvasively assessing tumors' early response to melphalan determined.<br />Materials and Methods: EC-tyrosine was synthesized in a three-step procedure and labeled with (99m)Tc. To assess cellular uptake kinetics, the percentage uptake of (99m)Tc-EC-tyrosine in the rat breast cancer cell line 13762 was measured. Planar imaging was performed in rats with 13762 cell-derived tumors. To determine the transport mechanisms of (99m)Tc-EC-tyrosine, a competitive inhibition study using L-tyrosine as an inhibitor was performed in vitro and in vivo. To assess tumors' response to melphalan, tumor-bearing rats were treated with different doses of melphalan, and planar imaging was performed 0 and 3 days after treatment. Immunohistochemical analyses were conducted to determine expressions of L-type amino acid transporter 1 and cellular proliferation marker Ki-67.<br />Results: L-tyrosine significantly inhibited (99m)Tc-EC-tyrosine uptake in vitro and in vivo. Tumor volume decreased in a dose-dependent manner with melphalan, and tumor/muscle ratios of (99m)Tc-EC-tyrosine were significantly reduced in treated groups. Immunohistochemical data indicated that about 70% of tumor cells in the melphalan-treated groups underwent apoptosis, and the changes in tumor/muscle ratios reflected the decreased percentage of viable cells in treated tumors.<br />Conclusions: These findings suggest that (99m)Tc-EC-tyrosine has great potential for monitoring tumor response to melphalan in breast tumor-bearing rats.<br /> (Published by Elsevier Inc.)
- Subjects :
- Amino Acid Transport System y+L metabolism
Animals
Chelating Agents chemical synthesis
Cysteine chemical synthesis
Dose-Response Relationship, Drug
Female
Immunohistochemistry
Ki-67 Antigen metabolism
Neoplasm Proteins metabolism
Organotechnetium Compounds chemical synthesis
Radionuclide Imaging
Rats
Rats, Inbred F344
Tissue Distribution
Treatment Outcome
Tyrosine chemical synthesis
Breast Neoplasms diagnostic imaging
Breast Neoplasms drug therapy
Chelating Agents chemistry
Cysteine chemistry
Melphalan pharmacology
Organotechnetium Compounds chemistry
Tyrosine chemistry
Subjects
Details
- Language :
- English
- ISSN :
- 1878-4046
- Volume :
- 20
- Issue :
- 1
- Database :
- MEDLINE
- Journal :
- Academic radiology
- Publication Type :
- Academic Journal
- Accession number :
- 22963724
- Full Text :
- https://doi.org/10.1016/j.acra.2012.08.005