Targeting USP8 Inhibits O‐GlcNAcylation of SLC7A11 to Promote Ferroptosis of Hepatocellular Carcinoma via Stabilization of OGT

Abstract

Hepatocellular carcinoma (HCC) is a lethal and aggressive human malignancy. The present study examins the anti‐tumor effects of deubiquitylating enzymes (DUB) inhibitors in HCC. It is found that the inhibitor of ubiquitin specific peptidase 8 (USP8) and DUB‐IN‐3 shows the most effective anti‐cancer responses. Targeting USP8 inhibits the proliferation of HCC and induces cell ferroptosis. In vivo xenograft and metastasis experiments indicate that inhibition of USP8 suppresses tumor growth and lung metastasis. DUB‐IN‐3 treatment or USP8 depletion decrease intracellular cystine levels and glutathione biosynthesis while increasing the accumulation of reactive oxygen species (ROS). Mechanistical studies reveal that USP8 stabilizes O‐GlcNAc transferase (OGT) via inhibiting K48‐specific poly‐ubiquitination process on OGT protein at K117 site, and STE20‐like kinase (SLK)‐mediated S716 phosphorylation of USP8 is required for the interaction with OGT. Most importantly, OGT O‐GlcNAcylates solute carrier family 7, member 11 (SLC7A11) at Ser26 in HCC cells, which is essential for SLC7A11 to import the cystine from the extracellular environment. Collectively, this study demonstrates that pharmacological inhibition or knockout of USP8 can inhibit the progression of HCC and induce ferroptosis via decreasing the stability of OGT, which imposes a great challenge that targeting of USP8 is a potential approach for HCC treatment.

ATR‐dependent ubiquitin‐specific protease 20 phosphorylation confers oxaliplatin and ferroptosis resistance

“…Total GSH was detected using the Glutathione Assay Kit (Beyotime Biotechnology) according to the instructions of manufacturer as we previously described 77 . The experiment was repeated three times with three replicates per sample.…”

“…Iron assay kit (Sigma; Cat. MAK025) was used for the measurement intracellular ferrous (Fe2+) iron according to the instructions of manufacturer as we previously described 77 . The experiment was repeated three times with three replicates per sample.…”

Impairment of FBXO31-mediated Ubiquitination of OGT Upregulates O-GlcNAcylation to Advance Endometrial Malignancy

“…OGT has been reported to be regulated by the balance of ubiquitination and deubiquitination 9,10,12,13 . The E3 ligases XIAP and E6AP could promote the ubiquitin-dependent proteasome degradation of OGT 10,11 .…”

“…Cancer cells often hijack embryonic programs to support their uncontrolled proliferation and cell fate transition, adopting a metabolic lifestyle relying on aerobic glycolysis (Warburg effect). Elevated O-GlcNAcylation has been observed in many cancer cell lines [5][6][7][8] , probably as a result of its increased nutrient consumption, or imbalanced enzymatic activity of OGT and OGA due to somatic mutations or altered protein stability [9][10][11][12][13] .…”

Ferroptosis in cancer (Review)

“…The study suggested that ME1 is a potential therapeutic target for the treatment of liver ischemia-reperfusion injury or other diseases associated with ferroptosis. Using drug screening, Tang et al ( 104 ) found that USP8 small molecule inhibitors can significantly inhibit the activity of liver cancer cells. Mechanism studies have shown that USP8 modified OGT protein through deubiquitination to improve the stability of the protein, which subsequently regulated SLC7A11 through glycosylation and inhibited ferroptosis in hepatocellular carcinoma, thus promoting the occurrence of liver cancer.…”