APR-246/PRIMA-1MET inhibits thioredoxin reductase 1 and converts the enzyme to a dedicated NADPH oxidase

Cell Death Dis. 2013 Oct 24;4(10):e881. doi: 10.1038/cddis.2013.417.


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.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Cell Death / drug effects
  • Cell Line, Tumor
  • Cell Survival / drug effects
  • Cytoprotection / drug effects
  • Gene Knockdown Techniques
  • Humans
  • NADPH Oxidases / metabolism*
  • Quinuclidines / pharmacology*
  • RNA, Small Interfering / metabolism
  • Rats
  • Reactive Oxygen Species / metabolism
  • Thioredoxin Reductase 1 / antagonists & inhibitors*
  • Thioredoxin Reductase 1 / metabolism


  • 2-hydroxymethyl-2-methoxymethylazabicyclo(2.2.2)octan-3-one
  • Quinuclidines
  • RNA, Small Interfering
  • Reactive Oxygen Species
  • NADPH Oxidases
  • Thioredoxin Reductase 1