Noninvasive optical imaging of cysteine protease activity using fluorescently quenched activity-based probes

Galia Blum, Georges Von Degenfeld, Milton J. Merchant, Helen M. Blau, Matthew Bogyo*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

387 Scopus citations


We have generated a series of quenched near-infrared fluorescent activity-based probes (qNIRF-ABPs) that covalently target the papain-family cysteine proteases shown previously to be important in multiple stages of tumorigenesis. These 'smart' probes emit a fluorescent signal only after covalently modifying a specific protease target. After intravenous injection of NIRF-ABPs into mice bearing grafted tumors, noninvasive, whole-body imaging allowed direct monitoring of cathepsin activity. Importantly, the permanent nature of the probes also allowed secondary, ex vivo biochemical profiling to identify specific proteases and to correlate their activity with whole-body images. Finally, we demonstrate that these probes can be used to monitor small-molecule inhibition of protease targets both biochemically and by direct imaging methods. Thus, NIRF-ABPs are (i) potentially valuable new imaging agents for disease diagnosis and (ii) powerful tools for preclinical and clinical testing of small-molecule therapeutic agents in vivo.

Original languageAmerican English
Pages (from-to)668-677
Number of pages10
JournalNature Chemical Biology
Issue number10
StatePublished - 20 Oct 2007
Externally publishedYes

Bibliographical note

Funding Information:
We thank P. Jackson (Stanford University) for the mouse fibroblast cells, G.P. Nolan (Stanford University) for the ecotropic FNX packaging cell line, S. Gambhir (Stanford University) for the U87MG cells, X. Chen (Stanford University) for the MDA-MB 435 human epithelial adenocarcinoma cells, and B. Cravatt (The Scripps Research Institute) for the MDA-MB 231 MFP human epithelial adenocarcinoma. This work was supported by the US National Institutes of Health National Technology Center for Networks and Pathways (grants U54 RR020843, R01 EB005011 and P01 CA072006), the US Department of Defense Breast Cancer Center of Excellence (grant DAMD-17-02-0693; to M.B.), a Susan G. Komen postdoctoral fellowship (to G.B.) and a grant from the Deutsche Forschungsgemeinschaft (DE 740/1-1; to G.v.D.).


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