Detection of Enzyme Activity and Inhibition during Studies in Solution, In Vitro and In Vivo with CatalyCEST MRI

Sanhita Sinharay, Edward A. Randtke, Christine M. Howison, Natalia Ignatenko, Mark "Marty" Pagel

Research output: Contribution to journalArticle

3 Citations (Scopus)

Abstract

Purpose: The detection of enzyme activities and evaluation of enzyme inhibitors have been challenging with magnetic resonance imaging (MRI). To address this need, we have developed a diamagnetic, nonmetallic contrast agent and a protocol known as catalyCEST MRI that uses chemical exchange saturation transfer (CEST) to detect enzyme activity as well as enzyme inhibition. Procedures: We synthesized a diamagnetic MRI contrast agent that has enzyme responsive and enzyme unresponsive CEST signals. We tested the ability of this agent to detect the activity of kallikrein 6 (KLK6) in biochemical solutions, in vitro and in vivo, with and without a KLK6 inhibitor. Results: The agent detected KLK6 activity in solution and also detected KLK6 inhibition by antithrombin III. KLK6 activity was detected during in vitro studies with HCT116 colon cancer cells, relative to the detection of almost no activity in a KLK6-knockdown HCT116 cell line and HCT116 cells treated with antithrombin III inhibitor. Finally, strong enzyme activity was detected within an in vivo HCT116 tumor model, while lower enzyme activity was detected in a KLK6 knockdown tumor model and in the HCT116 tumor model treated with antithrombin III inhibitor. In all cases, comparisons of the enzyme responsive and enzyme unresponsive CEST signals were critical for the detection of enzyme activity. Conclusions: This study has established that catalyCEST MRI with an exogenous diaCEST agent can evaluate enzyme activity and inhibition in solution, in vitro and in vivo.

Original languageEnglish (US)
Pages (from-to)1-9
Number of pages9
JournalMolecular Imaging and Biology
DOIs
StateAccepted/In press - Jul 19 2017

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Kallikreins
Magnetic Resonance Imaging
Enzymes
Antithrombin III
HCT116 Cells
Contrast Media
In Vitro Techniques
Neoplasms
Enzyme Inhibitors
Colonic Neoplasms
Cell Line

ASJC Scopus subject areas

  • Oncology
  • Radiology Nuclear Medicine and imaging
  • Cancer Research

Cite this

Detection of Enzyme Activity and Inhibition during Studies in Solution, In Vitro and In Vivo with CatalyCEST MRI. / Sinharay, Sanhita; Randtke, Edward A.; Howison, Christine M.; Ignatenko, Natalia; Pagel, Mark "Marty".

In: Molecular Imaging and Biology, 19.07.2017, p. 1-9.

Research output: Contribution to journalArticle

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