title: Naturally Occurring Isothiocyanates Exert Anticancer Effects by Inhibiting Deubiquitinating Enzymes.
abstract: The anticancer properties of cruciferous vegetables are well known and attributed to an abundance of isothiocyanates such as benzyl isothiocyanate (BITC) and phenethyl isothiocyanate (PEITC). While many potential targets of isothiocyanates have been proposed, a full understanding of the mechanisms underlying their anticancer activity has remained elusive. Here we report that BITC and PEITC effectively inhibit deubiquitinating enzymes (DUB), including the enzymes USP9x and UCH37, which are associated with tumorigenesis, at physiologically relevant concentrations and time scales. USP9x protects the antiapoptotic protein Mcl-1 from degradation, and cells dependent on Mcl-1 were especially sensitive to BITC and PEITC. These isothiocyanates increased Mcl-1 ubiquitination and either isothiocyanate treatment, or RNAi-mediated silencing of USP9x decreased Mcl-1 levels, consistent with the notion that USP9x is a primary target of isothiocyanate activity. These isothiocyanates also increased ubiquitination of the oncogenic fusion protein Bcr-Abl, resulting in degradation under low isothiocyanate concentrations and aggregation under high isothiocyanate concentrations. USP9x inhibition paralleled the decrease in Bcr-Abl levels induced by isothiocyanate treatment, and USP9x silencing was sufficient to decrease Bcr-Abl levels, further suggesting that Bcr-Abl is a USP9x substrate. Overall, our findings suggest that USP9x targeting is critical to the mechanism underpinning the well-established anticancer activity of isothiocyanate. We propose that the isothiocyanate-induced inhibition of DUBs may also explain how isothiocyanates affect inflammatory and DNA repair processes, thus offering a unifying theme in understanding the function and useful application of isothiocyanates to treat cancer as well as a variety of other pathologic conditions.
authors.affiliation: Department of Biology, Brandeis University, MS009, 415 South Street, Waltham, MA 02453-9110 USA.
authors.forename: Ann P
authors.initials: AP
authors.lastname: Lawson
authors.affiliation: Graduate Program in Biochemistry and Biophysics, Brandeis University, MS009, 415 South Street, Waltham, MA 02453-9110 USA.
authors.forename: Marcus J C
authors.initials: MJC
authors.lastname: Long
authors.affiliation: Department of Biology, Brandeis University, MS009, 415 South Street, Waltham, MA 02453-9110 USA.|Graduate Program in Molecular and Cellular Biology, Brandeis University, MS008, 415 South St., Waltham MA 02453-9110.
authors.forename: Rory T
authors.initials: RT
authors.lastname: Coffey
authors.affiliation: Department of Chemistry, Merkert Center, Boston College, 2609 Beacon Street, Chestnut Hill, MA 02467-3860 USA.
authors.forename: Yu
authors.initials: Y
authors.lastname: Qian
authors.affiliation: Department of Chemistry, Merkert Center, Boston College, 2609 Beacon Street, Chestnut Hill, MA 02467-3860 USA.
authors.forename: Eranthie
authors.initials: E
authors.lastname: Weerapana
authors.affiliation: UbiQ, Science Park 408, 1098 XH Amsterdam The Netherlands.
authors.forename: Farid
authors.initials: F
authors.lastname: El Oualid
authors.affiliation: Department of Biology, Brandeis University, MS009, 415 South Street, Waltham, MA 02453-9110 USA.|Department of Chemistry, Brandeis University, 415 South Street, Waltham, MA 02453-9110 USA.
authors.forename: Lizbeth
authors.initials: L
authors.lastname: Hedstrom
mesh_terms: D000818:Animals; D019556:COS Cells; D002522:Chlorocebus aethiops; D010450:Endopeptidases / Q000378:metabolism; D006367:HeLa Cells; D006801:Humans; D017879:Isothiocyanates / Q000494:pharmacology*; D020014:K562 Cells; D061986:MCF-7 Cells; D008546:Melanoma, Experimental; D051379:Mice; D041681:NIH 3T3 Cells; D025801:Ubiquitin / Q000378:metabolism; D043222:Ubiquitin Thiolesterase / Q000037:antagonists & inhibitors* / Q000378:metabolism; D043743:Ubiquitin-Protein Ligase Complexes / Q000037:antagonists & inhibitors* / Q000378:metabolism; D054875:Ubiquitination / Q000187:drug effects
chemical_list: D017879:Isothiocyanates; C506234:USP9X protein, human; D025801:Ubiquitin; C058305:phenethyl isothiocyanate; C031403:benzyl isothiocyanate; D043743:Ubiquitin-Protein Ligase Complexes; D010450:Endopeptidases; C421245:UCHL5 protein, human; D043222:Ubiquitin Thiolesterase; C581032:Uchl5 protein, mouse; C404328:Usp9x protein, mouse