Imaging human melanoma using a novel Tc-99m-labeled lactam bridge-cyclized alpha-MSH peptide

Abstract

In this study, the human melanoma targeting property of ^99mTc(EDDA)-HYNIC-AocNle-CycMSH _hex {hydrazinonicotinamide-8-aminooctanoic acid-Nle-c[Asp-His-DPhe-Arg-Trp-Lys]-CONH ₂} was determined in M21 human melanoma-xenografts to demonstrate its potential for human melanoma imaging. The IC ₅₀ value of HYNIC-AocNle-CycMSH _hex was 0.48 ± 0.01 nM in M21 human melanoma cells (1,281 receptors/cell). The M21 human melanoma uptake of ^99mTc(EDDA)-HYNIC-AocNle-CycMSH _hex was 4.03 ± 1.25, 3.26 ± 1.23 and 3.36 ± 1.48% ID/g at 0.5, 2 and 4 h post-injection, respectively. Approximately 92% of injected dose cleared out the body via urinary system at 2 h post-injection. ^99mTc(EDDA)-HYNIC-AocNle-CycMSH _hex showed high tumor/blood, tumor/muscle and tumor/skin uptake ratios after 2 h post-injection. The M21 human melanoma-xenografted tumor lesions were clearly visualized by SPECT/CT using ^99mTc(EDDA)-HYNIC-AocNle-CycMSH _hex as an imaging probe at 2 h post-injection. Overall, ^99mTc(EDDA)-HYNIC-AocNle-CycMSH _hex exhibited favorable human melanoma imaging property, highlighting its potential as an imaging probe for human metastatic melanoma detection.

Graphical abstract

SPECT/CT image of a M21 human melanoma-xenografted nude mouse using ^99mTc(EDDA)-HYNIC-AocNle-CycMSH _hex as an imaging probe.