Disulfiram and 6-Thioguanine synergistically inhibit the enzymatic activities of USP2 and USP21.

Affiliation

Lin HC(1), Kuan Y(2), Chu HF(3), Cheng SC(4), Pan HC(4), Chen WY(2), Sun CY(5), Lin TH(6).
Author information:
(1)Basic Research Division, Medical Research Department, Taipei Veterans General Hospital, Taipei 112, Taiwan; Department of Life Sciences and Institute of Genome Sciences, National Yang Ming Chiao Tung University, Taipei 112, Taiwan.
(2)Program in Molecular Medicine, National Yang Ming Chiao Tung University and Acedemia Sinica, Taipei 112, Taiwan; Institute of Biochemistry and Molecular Biology, National Yang Ming Chiao Tung University, Taipei 112, Taiwan.
(3)Department of Life Sciences and Institute of Genome Sciences, National Yang Ming Chiao Tung University, Taipei 112, Taiwan; Biomedical Industry Ph.D. Program, National Yang Ming Chiao Tung University, Taipei 112, Taiwan.
(4)Department of Nephrology, Chang Gung Memorial Hospital, Keelung 204, Taiwan.
(5)Department of Nephrology, Chang Gung Memorial Hospital, Keelung 204, Taiwan. Electronic address: [Email]
(6)Basic Research Division, Medical Research Department, Taipei Veterans General Hospital, Taipei 112, Taiwan; Department of Life Sciences and Institute of Genome Sciences, National Yang Ming Chiao Tung University, Taipei 112, Taiwan; Institute of Biochemistry and Molecular Biology, National Yang Ming Chiao Tung University, Taipei 112, Taiwan; Biomedical Industry Ph.D. Program, National Yang Ming Chiao Tung University, Taipei 112, Taiwan. Electronic address: [Email]

Abstract

Disulfiram is a promising repurposed drug that, combining with radiation and chemotherapy, exhibits effective anticancer activities in several preclinical models. The cellular metabolites of disulfiram have been established, however, the intracellular targets of disulfiram remain largely unexplored. We have previously reported that disulfiram suppresses the coronaviral papain-like proteases through attacking their zinc-finger domains, suggesting an inhibitory function potentially on other proteases with similar catalytic structures. Ubiquitin-specific proteases (USPs) share a highly-conserved zinc-finger subdomain that structurally similar to the papain-like proteases and are attractive anticancer targets as upregulated USPs levels are found in a variety of tumors. Here, we report that disulfiram functions as a competitive inhibitor for both USP2 and USP21, two tumor-related deubiquitinases. In addition, we also observed a synergistic inhibition of USP2 and USP21 by disulfiram and 6-Thioguanine (6TG), a clinical drug for acute myeloid leukemia. Kinetic analyses revealed that both drugs exhibited a slow-binding mechanism, moderate inhibitory parameters, and a synergistically inhibitory effect on USP2 and USP21, suggesting the potential combinatory use of these two drugs for USPs-related tumors. Taken together, our study provides biochemical evidence for repurposing disulfiram and 6TG as a combinatory treatment in clinical applications.