PK11007 Covalently Inhibits Thioredoxin Reductase 1 to Induce Oxidative Stress and Autophagy Impairment in NSCLC Cells

Selenoprotein thioredoxin reductase 1 (TXNRD1) is frequently upregulated in various cancer cells to sustain cellular redox homeostasis, and its inhibition has emerged as a promising anti-cancer strategy. In this study, we identified PK11007, a thiol-modifying compound previously characterized as a p53 reactivator, as a potent inhibitor of TXNRD1. PK11007 irreversibly inhibited recombinant TXNRD1 in a time- and dose-dependent manner. Using differential scanning fluorimetry (DSF) and LC-MS/MS analysis, we confirmed that PK11007 covalently modifies the C-terminal redox motif (Cys⁴⁹⁷-Sec⁴⁹⁸) of TXNRD1. In non-small cell lung cancer (NSCLC) H1299 cells, PK11007-induced TXNRD1 inhibition disrupted cellular redox balance, leading to impaired autophagy flux and cell death. Similar autophagy suppression was observed in TXNRD1-knockdown cells, as well as pharmacological inhibition of TXNRD1 by Auranofin (AF) and TXNRD1 inhibitor 1 (TRi-1). Taken together, these findings highlight that oxidative stress contributes to the cytotoxic effects of PK11007 and uncover autophagy disorder as a downstream consequence of TXNRD1 inhibition.