A chelating derivative of alpha-melanocyte stimulating hormone as a potential imaging agent for malignant melanoma.
A chelating derivative of alpha-melanocyte stimulating hormone (MSH) has been synthesised, in which two molecules of the hormone are cross-linked by diethylenetriamine pentaacetic acid (DTPA). This compound, bisMSH-DTPA, was equipotent with MSH in an in vitro tyrosinase assay with Cloudman S91 melanoma cells. When DBA/2 mice bearing the same tumour were injected with bisMSH-DTPA labelled with the gamma-emitting isotope indium-111 (111In), the radioactivity became rapidly associated with the melanoma tissue. By 24 h post-injection, radioactivity in tumour tissue was significantly higher (P less than 0.001) than in spleen, lung, brain, eye and skin. Uptake of radioactivity by the tumours was inhibited by a 200-fold molar excess of MSH, whereas uptake by liver, kidney, spleen, lung, brain, eye and skin was unaffected. We conclude that bisMSH-DTPA may offer an alternative to antibody targeting in the imaging of malignant melanoma.
Bard
D R
DR
Strangeways Research Laboratory, Worts' Causeway, Cambridge, UK.
Knight
C G
CG
Page-Thomas
D P
DP
D000818:Animals; D004355:Drug Stability; D007205:Indium Radioisotopes; D009074:Melanocyte-Stimulating Hormones / Q000031:analogs & derivatives / Q000493:pharmacokinetics; D008545:Melanoma / Q000000981:diagnostic imaging*; D051379:Mice; D008811:Mice, Inbred DBA; D004369:Pentetic Acid; D011877:Radionuclide Imaging; D014018:Tissue Distribution
D007205:Indium Radioisotopes; D004369:Pentetic Acid; D009074:Melanocyte-Stimulating Hormones