1. A novel radiopharmaceutical for detection of malignant melanoma, based on melanin formation: 3-iodo-4-hydroxyphenyl-L-cysteine.
- Author
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Nishii R, Kawai K, Garcia Flores L 2nd, Kataoka H, Jinnouchi S, Nagamachi S, Arano Y, and Tamura S
- Subjects
- Animals, Cysteine analogs & derivatives, Cysteine chemical synthesis, Isotope Labeling methods, Mice, Mice, Inbred C57BL, Organ Specificity, Predictive Value of Tests, Radiopharmaceuticals chemical synthesis, Radiopharmaceuticals pharmacokinetics, Skin Neoplasms diagnostic imaging, Skin Neoplasms metabolism, Tissue Distribution, Tomography, Emission-Computed, Single-Photon methods, Whole-Body Counting, Cysteine pharmacokinetics, Melanins biosynthesis, Melanoma diagnostic imaging, Melanoma metabolism
- Abstract
The aim of this study was to develop a new artificial amino acid radiopharmaceutical labelled with radioiodine for detection of malignant melanoma, based on melanin formation. By considering the affinity for tyrosinase, a starting enzyme on the branching point to melanin biosynthesis, 3-[125I]iodo-4-hydroxyphenyl-L-cysteine (125I-L-PC) was synthesized and evaluated biologically. Labelling of 125I-L-PC using the chloramine-T method was carried out conveniently and efficiently in a short period of time, with high specific activity. In a biodistribution study, 125I-L-PC showed a low accumulation in normal tissue and relative retention in B16 melanoma. A high contrast image of peripheral tumour was obtained during autoradiography. During an in vitro accumulation study, inhibition of 125I-L-PC with a tyrosinase inhibitor suggested interaction of this tracer with tyrosinase. It indicates that the uptake mechanism of 125I-L-PC to melanoma tissue was dependent on high tyrosinase activity in melanoma cells. Thus, 125I-L-PC appears to be a promising radioiodinated amino acid radiopharmaceutical for imaging malignant melanoma in relation to melanin formation, namely specific metabolism with high tyrosinase activity.
- Published
- 2003
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