Tc-99m-labeled RGD-conjugated alpha-melanocyte stimulating hormone hybrid peptides with reduced renal uptake

Amino Acids. 2015 Apr;47(4):813-23. doi: 10.1007/s00726-014-1911-z. Epub 2015 Jan 4.

Abstract

The purpose of this study was to examine whether the replacement of the positively-charged Lys or Arg linker with a neutral linker could reduce the renal uptake of Arg-Gly-Asp (RGD)-conjugated alpha-melanocyte stimulating hormone (α-MSH) hybrid peptide. The RGD motif {cyclic(Arg-Gly-Asp-DTyr-Asp)} was coupled to [Cys(3,4,10), D-Phe(7), Arg(11)]α-MSH3-13 {(Arg(11))CCMSH} through the neutral βAla or Ahx {aminohexanoic acid} linker (replacing the Lys or Arg linker) to generate novel RGD-βAla-(Arg(11))CCMSH and RGD-Ahx-(Arg(11))CCMSH hybrid peptides. The receptor-binding affinity and cytotoxicity of RGD-βAla-(Arg(11))CCMSH and RGD-Ahx-(Arg(11))CCMSH were determined in B16/F1 melanoma cells. The melanoma targeting and imaging properties of (99m)Tc-RGD-βAla-(Arg(11))CCMSH and (99m)Tc-RGD-Ahx-(Arg(11))CCMSH were determined in B16/F1 melanoma-bearing C57 mice. The replacement of the Lys or Arg linker with the βAla or Ahx linker retained nanomolar receptor-binding affinities and remarkable cytotoxicity of RGD-βAla-(Arg(11))CCMSH and RGD-Ahx-(Arg(11))CCMSH. The receptor-binding affinities of RGD-βAla-(Arg(11))CCMSH and RGD-Ahx-(Arg(11))CCMSH were 0.8 ± 0.05 and 1.3 ± 0.1 nM. Three-hour incubation with 0.1 µM of RGD-βAla-(Arg(11))CCMSH and RGD-Ahx-(Arg(11))CCMSH decreased the survival percentages of B16/F1 cells by 71 and 67 % as compared to the untreated control cells 5 days post the treatment. The replacement of the Arg linker with the βAla or Ahx linker reduced the non-specific renal uptake of (99m)Tc-RGD-βAla-(Arg(11))CCMSH and (99m)Tc-RGD-Ahx-(Arg(11))CCMSH by 62 and 61 % at 2 h post-injection. (99m)Tc-RGD-βAla-(Arg(11))CCMSH displayed higher melanoma uptake than (99m)Tc-RGD-Ahx-(Arg(11))CCMSH at 0.5, 2, 4, and 24 h post-injection. Enhanced tumor to kidney uptake ratio of (99m)Tc-RGD-βAla-(Arg(11))CCMSH warranted the further evaluation of (188)Re-labeled RGD-βAla-(Arg(11))CCMSH as a novel MC1 receptor-targeting therapeutic peptide for melanoma treatment in the future.

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Cell Line, Tumor
  • Female
  • Humans
  • Kidney / metabolism*
  • Melanoma / drug therapy*
  • Melanoma / metabolism
  • Mice
  • Mice, Inbred C57BL
  • Oligopeptides / chemistry*
  • Oligopeptides / metabolism
  • Radiopharmaceuticals / administration & dosage
  • Radiopharmaceuticals / chemical synthesis
  • Radiopharmaceuticals / chemistry
  • Radiopharmaceuticals / pharmacokinetics*
  • Receptor, Melanocortin, Type 1 / antagonists & inhibitors
  • Receptor, Melanocortin, Type 1 / genetics
  • Receptor, Melanocortin, Type 1 / metabolism
  • Technetium / chemistry*
  • Technetium / metabolism
  • Tissue Distribution
  • alpha-MSH / administration & dosage
  • alpha-MSH / chemical synthesis*
  • alpha-MSH / chemistry
  • alpha-MSH / pharmacokinetics*

Substances

  • Oligopeptides
  • Radiopharmaceuticals
  • Receptor, Melanocortin, Type 1
  • alpha-MSH
  • Technetium
  • arginyl-glycyl-aspartic acid