Abstract 1510: Glutathione-oxidation of ovarian tumor deubiquitinase-1 promotes lung adenocarcinoma survival through stabilizing system xc-

Abstract The small thiol antioxidant glutathione (GSH) is critical in maintaining redox homeostasis that is essential in combating oxidative stress. We and others have reported increases of GSH in KRAS-mutant lung adenocarcinoma (LUAD). However, little is known about GSH-dependent protein oxidation (S-glutathionylation- PSSG) in LUAD development and progression. We recently discovered that glutaredoxin (GLRX), the enzyme that reverses PSSG, is decreased in human LUAD, and that KrasG12D-induced lung tumorigenesis is enhanced in mice lacking Glrx. To elucidate the link between PSSG and GSH levels we conducted a redox proteomics screen and identified ovarian tumor deubiquitinase-1 (OTUB1) as a glutathionylation target. We determined that OTUB1 glutathionylation at Cys23 and Cys204 is a regulator of GSH in LUAD cell lines and organoids. Mechanistically, glutathionylation of OTUB1, specifically at Cys23, promoted interaction with the E2-conjugating enzyme UBCH5A, leading to diminished ubiquitination and proteasomal degradation of the active subunit of system xC−, SLC7A11, thereby augmenting GSH. The cystine-glutamate antiporter, System xC−, has been linked to aggressive tumors with worse survival. The use of a specific inhibitor of OTUB1-SSG, led to decreased SLC7A11 and GSH levels in LUAD cell lines. These findings provide an intricate link between S-glutathionylation of OTUB1, GSH and system xC− and provide a mechanism by which LUAD cells combat oxidative stress. Avenues to interfere with OTUB1-SSG may provide a promising therapeutic approach to overcome LUAD progression and resistance. Funded by: R01 CA273238 Citation Format: Reem Aboushousha, Jos van der Velden, Nicholas Hamilton, Cuixia Erickson, David J. Seward, Jianing Li, Yvonne M. Janssen-Heininger. Glutathione-oxidation of ovarian tumor deubiquitinase-1 promotes lung adenocarcinoma survival through stabilizing system xc- [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2025; Part 1 (Regular Abstracts); 2025 Apr 25-30; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2025;85(8_Suppl_1):Abstract nr 1510.