CRISPR screens uncover protective effect of PSTK as a regulator of chemotherapy-induced ferroptosis in hepatocellular carcinoma

Abstract

Background Hepatocellular carcinoma (HCC) is among the most common forms of cancer and is associated with poor patient outcomes. The emergence of therapeutic resistance has hampered the efficacy of targeted treatments employed to treat HCC patients to date. In this study, we conducted a series of CRISPR/Cas9 screens to identify genes associated with synthetic lethality capable of improving HCC patient clinical responses. Methods CRISPR-based loss-of-function genetic screens were used to target 18,053 protein-coding genes in HCC cells to identify chemotherapy-related synthetic lethal genes in these cells. Synergistic effects were analyzed through in vitro and in vivo analyses, while related mechanisms were explored through RNA-seq and metabolomics analyses. Potential inhibitors of identified genetic targets were selected through high-throughput virtual screening. Results The inhibition of phosphoseryl-tRNA kinase (PSTK) was found to increase HCC cell sensitivity to chemotherapeutic treatment. PSTK was associated with the suppression of chemotherapy-induced ferroptosis in HCC cells, and the depletion of PSTK resulted in the inactivation of glutathione peroxidative 4 (GPX4) and the disruption of glutathione (GSH) metabolism owing to the inhibition of selenocysteine and cysteine synthesis, thus enhancing the induction of ferroptosis upon targeted chemotherapeutic treatment. Punicalin, an agent used to treat hepatitis B virus (HBV), was identified as a possible PSTK inhibitor that exhibited synergistic efficacy when applied together with Sorafenib to treat HCC in vitro and in vivo. Conclusions These results highlight a key role for PSTK as a mediator of resistance to targeted therapeutic treatment in HCC cells that functions by suppressing ferroptotic induction. PSTK inhibitors may thus represent ideal candidates for overcoming drug resistance in HCC.

Characterization of the Ferroptosis-Related Genes for Prognosis and Immune Infiltration in Low-Grade Glioma

“…It is characterized by dysbalance in the regulation of intracellular iron metabolism and membrane lipid peroxidation ( Ursini and Maiorino, 2020 ). The function of ferroptosis in several types of cancer has been reported previously, including breast cancer ( Li H. et al, 2022 ), hepatocellular carcinoma ( Chen et al, 2022 ), gastric cancer ( Zhang et al, 2021 ), head neck squamous cell carcinoma ( Lu et al, 2021 ), lung cancer ( Li and Liu, 2022 ), renal cell carcinoma ( Du et al, 2021 ), ovarian cancer ( Li H.-W. et al, 2022 ), and pancreatic cancer ( Liu et al, 2021 ). Mou et al (2022 ) has found that for LGG the SAT1 activation is closely related to ferroptosis upon ROS induction.…”

Targeting Ferroptosis Pathway to Combat Therapy Resistance and Metastasis of Cancer

“…It induces the expression of SLC7A11 in a TEAD-dependent manner and maintains the homeostasis of intracellular GSH, thereby suppressing sorafenib-induced ferroptosis in HCC cells. Inhibition of the antioxidant pathway regulated by YAP/TAZ and ATF4 may resensitize drug-resistant HCC to sorafenib ( Chen et al, 2022 ). In addition, dihydroartemisinin (DHA) can enhance the anticancer effect of sorafenib by downregulating GSH-related proteins in the iron metabolism pathway, thereby enhancing the function of sorafenib in inducing ferroptosis in HepG2 cells ( Cui et al, 2022 ).…”

Mechanism of Ferroptosis and Its Role in Spinal Cord Injury

“…RSL, an inducer of ferroptosis, binds to selenocysteine of GPX4 and inhibits its phospholipid peroxidase activity, thereby triggering ferroptosis, which could be inhibited by GPX4 overexpression ( 54 ). Inhibition of phosphoseryl-tRNA kinase (PSTK), the key enzyme in selenocysteine synthesis, inactivates GPX4 while simultaneously inhibiting GSH biosynthesis, inducing ferroptosis ( 65 ). It has been shown that over physiologic concentrations of Se upregulate GPX4 transcription, suggesting a role for Se in ferroptosis ( 66 ).…”