Synthesis and evaluation of a novel fluorescent photoprobe for imaging matrix metalloproteinases

Bioconjug Chem. 2008 May;19(5):1001-8. doi: 10.1021/bc700409j. Epub 2008 Apr 9.

Abstract

The measurement of matrix metalloproteinase (MMP) activity in diseases like inflammation, oncogenesis, or atherosclerosis in vivo is highly desirable. Fine-tuned pyrimidine-2,4,6-triones (barbiturates) offer nonpeptidyl lead structures for developing imaging agents for specifically visualization of activated MMPs in vivo. The aim of this study was to modify a C-5-disubstituted barbiturate and thus design a highly affine, nonpeptidic, optical MMP inhibitor (MMPI)-ligand for imaging of activated MMPs in vivo. A convergent 10 step synthesis was developed, starting with a malonic ester and (4-bromophenoxy)benzene to generate 5-bromo-pyrimidine-2,4,6-trione as the key intermediate. To minimize the interactions between activated MMPs and the dye of the conjugate 6, a PEGylated piperazine derivative was used as a spacer and an azide as a protected amino function. After linking both building blocks, reducing the azide ( Staudinger reaction) and labeling with Cy 5.5, we obtained the nonhydroxamate MMP inhibitor 6 with high affinity (IC 50-value: 48 nM for MMP-2) measured in a fluorogenic assay using commercially available MMP-substrates and the purified enzyme. Zymography revealed an efficient blocking of enzyme activity of purified MMP-2 and MMP-9 and of MMP-containing cell supernatants (HT-1080), (A-673) using the PEGylated barbiturate 5. Fluorescence microscopy studies using a highly (A-673) and a moderate (HT-1080) MMP-2 secreting cell line showed efficient binding of the Cy 5.5 labeled tracer 6 to the MMP-2 positive cells while MMP-2 negative cells (MCF-7) did not bind. Therefore, this new barbiturate-based MMP-probe has a high affinity and specificity toward MMP-2 and -9 and is thus a promising candidate for sensitive MMP detection in vivo.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Barbiturates / chemical synthesis*
  • Barbiturates / chemistry*
  • Barbiturates / pharmacology
  • Binding Sites
  • Binding, Competitive
  • Blotting, Western
  • Diagnostic Imaging
  • Fluorescent Dyes / chemical synthesis*
  • Fluorescent Dyes / chemistry*
  • Fluorescent Dyes / pharmacology
  • Humans
  • Ligands
  • Matrix Metalloproteinase 2 / chemistry*
  • Matrix Metalloproteinase 2 / metabolism
  • Matrix Metalloproteinase 9 / chemistry*
  • Matrix Metalloproteinase 9 / metabolism
  • Matrix Metalloproteinase Inhibitors
  • Microscopy, Fluorescence / methods
  • Molecular Structure
  • Polymerase Chain Reaction / methods
  • Protease Inhibitors / chemical synthesis
  • Protease Inhibitors / chemistry
  • Protease Inhibitors / pharmacology
  • Sensitivity and Specificity
  • Structure-Activity Relationship
  • Tumor Cells, Cultured

Substances

  • Barbiturates
  • Fluorescent Dyes
  • Ligands
  • Matrix Metalloproteinase Inhibitors
  • Protease Inhibitors
  • Matrix Metalloproteinase 2
  • Matrix Metalloproteinase 9