APR-246/PRIMA-1MET inhibits thioredoxin reductase 1 and converts the enzyme to a dedicated NADPH oxidase.
Cell Death Dis 2013;
4:e881. [PMID:
24157875 PMCID:
PMC3920950 DOI:
10.1038/cddis.2013.417]
[Citation(s) in RCA: 135] [Impact Index Per Article: 12.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/29/2013] [Revised: 09/13/2013] [Accepted: 09/23/2013] [Indexed: 01/05/2023]
Abstract
The low-molecular-weight compound APR-246 (PRIMA-1(MET)) restores wild-type conformation and function to mutant p53, and triggers apoptosis in tumor cells. We show here that APR-246 also targets the selenoprotein thioredoxin reductase 1 (TrxR1), a key regulator of cellular redox balance. APR-246 inhibited both recombinant TrxR1 in vitro and TrxR1 in cells. A Sec-to-Cys mutant of TrxR1 was not inhibited by APR-246, suggesting targeting of the selenocysteine residue in wild-type TrxR1. Preheated APR-246 and its conversion product methylene quinuclidinone (MQ) were much more efficient TrxR1 inhibitors than APR-246 itself, indicating that MQ is the active compound responsible for TrxR1 enzyme inhibition. TrxR1 inhibited by MQ was still functional as a pro-oxidant NADPH oxidase. Knockdown of TrxR1 caused a partial and reproducible attenuation of APR-246-induced tumor cell death independently of p53 status. Cellular TrxR1 activity was also inhibited by APR-246 irrespective of p53 status. We show that APR-246 can directly affect cellular redox status via targeting of TrxR1. Our findings provide an explanation for the previously observed effects of APR-246 on tumor cells lacking mutant p53.
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