Optical imaging of matrix metalloproteinase-7 activity in vivo using a proteolytic nanobeacon

Randy L. Scherer, Michael N. VanSaun, J. Oliver McIntyre, Lynn M. Matrisian

Research output: Contribution to journalArticle

75 Scopus citations

Abstract

Matrix metalloproteinases (MMPs) are extracellular proteolytic enzymes involved in tumor progression. We present the in vivo detection and quantitation of MMP7 activity using a specific near-infrared polymer-based proteolytic beacon, PB-M7NIR. PB-M7NIR is a pegylated polyamidoamine PAMAM-Generation 4 dendrimer core covalently coupled to a Cy5.5-labeled peptide representing a selective substrate that monitors MMP7 activity (sensor) and AF750 as an internal reference to monitor relative substrate concentration (reference). In vivo imaging of tumors expressing MMP7 had a median sensor to reference ratio 2.2-fold higher than a that of a bilateral control tumor. Ex vivo imaging of intestines of multiple intestinal neoplasia (APC Min) mice injected systemically with PB-M7NIR revealed a sixfold increase in the sensor to reference ratio in the adenomas of APC Min mice compared with control intestinal tissue or adenomas from MMP7-null Min mice. PB-M7NIR detected tumor sizes as small as 0.01 cm 2, and the sensor to reference ratio was independent of tumor size. Histologic sectioning of xenograft tumors localized the proteolytic signal to the extracellular matrix; MMP7-overexpressing tumors displayed an approximately 300-fold enhancement in the sensor to reference ratio compared with nonexpressing tumor cells. In APC Min adenomas, the proteolytic signal colocalized with the endogenously expressed MMP7 protein, with sensor to reference ratios approximately sixfold greater than that of normal intestinal epithelium. PB-M7NIR provides a useful reagent for the in vivo and ex vivo quantitation and localization of MMP-selective proteolytic activity.

Original languageEnglish (US)
Pages (from-to)118-131
Number of pages14
JournalMolecular imaging
Volume7
Issue number3
DOIs
StatePublished - May 2008

ASJC Scopus subject areas

  • Biotechnology
  • Molecular Medicine
  • Biomedical Engineering
  • Radiology Nuclear Medicine and imaging
  • Condensed Matter Physics

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