Reduced nonprotein thiols inhibit activation and function of MMP-9: implications for chemoprevention

Free Radic Biol Med. 2006 Oct 15;41(8):1315-24. doi: 10.1016/j.freeradbiomed.2006.07.014. Epub 2006 Jul 15.

Abstract

Clinical studies demonstrate a positive correlation between the extent of matrix metalloproteinase (MMP) activation and malignant progression of precancerous lesions. Therefore, identification of effective, well-tolerated MMP inhibitors represents a rational chemopreventive strategy. A variety of agents, including proteinases and thiol-oxidizing compounds, activate MMPs by initiating release of the propeptide's cysteine sulfur "blockage" of the MMP active site. Despite the importance of the propeptide's cysteine thiol in preserving MMP latency, limited studies have evaluated the effects of reduced thiols on MMP function. This study investigated the effects of two naturally occurring nonprotein thiols, i.e., glutathione (GSH) and N-acetylcysteine (NAC), on activation, function, and cellular-extracellular matrix interactions of the basement-membrane-degrading gelatinase, MMP-9. Our results reveal that NAC and GSH employ protein S-thiolation to inhibit organomercurial activation of pro-MMP-9. Gelatinase activity assays showed that GSH and NAC significantly inhibited MMP-9 but not MMP-2 function, implying isoform structural specificity. Immunoblot analyses, which suggested GSH interacts with MMP-9's active-site Zn, were corroborated by computational molecular modeling. Cell invasion assays revealed that NAC enhanced endostatin's ability to inhibit human cancer cell invasion. Collectively, these data demonstrate that nonprotein thiols suppress MMP-9 activation and function and introduce the prospect for their use in chemopreventive applications.

Publication types

  • Research Support, N.I.H., Extramural

MeSH terms

  • Acetylcysteine / pharmacology*
  • Anticarcinogenic Agents / pharmacology
  • Catalytic Domain
  • Cell Line, Tumor
  • Chemoprevention
  • Enzyme Activation / drug effects
  • Glutathione / pharmacology*
  • Humans
  • Matrix Metalloproteinase 2 / metabolism
  • Matrix Metalloproteinase 9 / chemistry
  • Matrix Metalloproteinase Inhibitors*
  • Models, Molecular
  • Neoplasms / drug therapy
  • Neoplasms / enzymology
  • Neoplasms / prevention & control
  • Oxidation-Reduction
  • Phenylmercuric Acetate / analogs & derivatives
  • Phenylmercuric Acetate / pharmacology
  • Protein Conformation
  • Zinc / metabolism

Substances

  • Anticarcinogenic Agents
  • Matrix Metalloproteinase Inhibitors
  • 4-aminophenylmercuriacetate
  • Matrix Metalloproteinase 2
  • Matrix Metalloproteinase 9
  • Glutathione
  • Zinc
  • Phenylmercuric Acetate
  • Acetylcysteine