title: Functional imaging of legumain in cancer using a new quenched activity-based probe.
abstract: Legumain is a lysosomal cysteine protease whose biological function remains poorly defined. Legumain activity is up-regulated in most human cancers and inflammatory diseases most likely as the result of high expression in populations of activated macrophages. Within the tumor microenvironment, legumain activity is thought to promote tumorigenesis. To obtain a greater understanding of the role of legumain activity during cancer progression and inflammation, we developed an activity-based probe that becomes fluorescent only upon binding active legumain. This probe is highly selective for legumain, even in the context of whole cells and tissues, and is also a more effective label of legumain than previously reported probes. Here we present the synthesis and application of our probe to the analysis of legumain activity in primary macrophages and in two mouse models of cancer. We find that legumain activity is highly correlated with macrophage activation and furthermore that it is an ideal marker for primary tumor inflammation and early stage metastatic lesions.
authors.affiliation: Cancer Biology Program, Department of Pathology, Stanford School of Medicine, 300 Pasteur Drive, Stanford, California 94305-5324, United States.
authors.forename: Laura E
authors.initials: LE
authors.lastname: Edgington
authors.forename: Martijn
authors.initials: M
authors.lastname: Verdoes
authors.forename: Alberto
authors.initials: A
authors.lastname: Ortega
authors.forename: Nimali P
authors.initials: NP
authors.lastname: Withana
authors.forename: Jiyoun
authors.initials: J
authors.lastname: Lee
authors.forename: Salahuddin
authors.initials: S
authors.lastname: Syed
authors.forename: Michael H
authors.initials: MH
authors.lastname: Bachmann
authors.forename: Galia
authors.initials: G
authors.lastname: Blum
authors.forename: Matthew
authors.initials: M
authors.lastname: Bogyo
mesh_terms: D000818:Animals; D002460:Cell Line; D003546:Cysteine Endopeptidases / Q000378:metabolism*; D004195:Disease Models, Animal; D004591:Electrophoresis, Polyacrylamide Gel; D005456:Fluorescent Dyes / Q000737:chemistry / Q000493:pharmacokinetics*; D006801:Humans; D008264:Macrophages / Q000201:enzymology / Q000378:metabolism*; D051379:Mice; D015394:Molecular Structure; D009374:Neoplasms, Experimental / Q000175:diagnosis* / Q000201:enzymology / Q000378:metabolism; D000099240:Asparaginyl Endopeptidase
chemical_list: D003546:Cysteine Endopeptidases; D005456:Fluorescent Dyes; D000099240:Asparaginyl Endopeptidase