title: APR-246/PRIMA-1MET inhibits thioredoxin reductase 1 and converts the enzyme to a dedicated NADPH oxidase.
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.
authors.affiliation: Division of Biochemistry, Department of Medical Biochemistry and Biophysics, Karolinska Institutet, Stockholm, Sweden.
authors.forename: X
authors.initials: X
authors.lastname: Peng
authors.forename: M-Q-Z
authors.initials: MQ
authors.lastname: Zhang
authors.forename: F
authors.initials: F
authors.lastname: Conserva
authors.forename: G
authors.initials: G
authors.lastname: Hosny
authors.forename: G
authors.initials: G
authors.lastname: Selivanova
authors.forename: V J N
authors.initials: VJ
authors.lastname: Bykov
authors.forename: E S J
authors.initials: ES
authors.lastname: Arnér
authors.forename: K G
authors.initials: KG
authors.lastname: Wiman
mesh_terms: D000818:Animals; D016923:Cell Death / Q000187:drug effects; D045744:Cell Line, Tumor; D002470:Cell Survival / Q000187:drug effects; D019610:Cytoprotection / Q000187:drug effects; D055785:Gene Knockdown Techniques; D006801:Humans; D019255:NADPH Oxidases / Q000378:metabolism*; D011812:Quinuclidines / Q000494:pharmacology*; D034741:RNA, Small Interfering / Q000378:metabolism; D051381:Rats; D017382:Reactive Oxygen Species / Q000378:metabolism; D054481:Thioredoxin Reductase 1 / Q000037:antagonists & inhibitors* / Q000378:metabolism
chemical_list: D011812:Quinuclidines; D034741:RNA, Small Interfering; D017382:Reactive Oxygen Species; D019255:NADPH Oxidases; D054481:Thioredoxin Reductase 1; C533410:eprenetapopt