Development of a Bioluminescent Nitroreductase Probe for Preclinical Imaging.

Anzhelika G Vorobyeva,Aurélien Godinat,Juri G Gelovani,Elena A Dubikovskaya,Kjetil B Lund,Grigory G Karateev,Kevin P Francis,Michael Stanton,Emmet Mccormack,Elizabeth Allen,Mark Tangney

doi:10.1371/journal.pone.0131037

Abstract

Bacterial nitroreductases (NTRs) have been widely utilized in the development of novel antibiotics, degradation of pollutants, and gene-directed enzyme prodrug therapy (GDEPT) of cancer that reached clinical trials. In case of GDEPT, since NTR is not naturally present in mammalian cells, the prodrug is activated selectively in NTR-transformed cancer cells, allowing high efficiency treatment of tumors. Currently, no bioluminescent probes exist for sensitive, non-invasive imaging of NTR expression. We therefore developed a "NTR caged luciferin" (NCL) probe that is selectively reduced by NTR, producing light proportional to the NTR activity. Here we report successful application of this probe for imaging of NTR in vitro, in bacteria and cancer cells, as well as in vivo in mouse models of bacterial infection and NTR-expressing tumor xenografts. This novel tool should significantly accelerate the development of cancer therapy approaches based on GDEPT and other fields where NTR expression is important.

Highlights

The nitroreductase (NTR) family of enzymes are widespread amongst bacteria and are known to metabolize nitrosubstituted compounds and quinones using NADH or NADPH as reducing agents [1,2,3,4]
They are important for the development of novel antibiotics being the main target for the treatment of infections caused by bacteria, e.g. Mycobacterium tuberculosis [5], Helicobacter pylori [6] and by parasites, e.g. Trypanosoma [7], Giardia and Entamoeba [8]
Their enzymatic activity in gut microbiota is linked to carcinogen production and etiology of colorectal cancer [9,10]. They are used in biotechnology for degradation of environmental contaminants [1]. Due to their absence in mammalian cells they are utilized as activating enzymes in gene-directed enzyme prodrug therapy (GDEPT) approaches for cancer

Summary

Introduction

The nitroreductase (NTR) family of enzymes are widespread amongst bacteria and are known to metabolize nitrosubstituted compounds and quinones using NADH or NADPH as reducing agents [1,2,3,4] They are important for the development of novel antibiotics being the main target for the treatment of infections caused by bacteria, e.g. Mycobacterium tuberculosis [5], Helicobacter pylori [6] and by parasites, e.g. Trypanosoma [7], Giardia and Entamoeba [8]. Their enzymatic activity in gut microbiota is linked to carcinogen production and etiology of colorectal cancer [9,10]. Due to their absence in mammalian cells they are utilized as activating enzymes in gene-directed enzyme prodrug therapy (GDEPT) approaches for cancer

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Conclusion