CRISPR screens uncover CRTC3 as a regulator of IFN-γ induced ferroptosis in hepato-cellular carcinoma [RNA-seq]

Gamma interferon (IFN-γ) was reported to exhibit anti-tumor effects via inducing ferroptosis. Based on genome-wide CRISPR/Cas9 knockout screens, we discovered that cAMP response ele-ment binding protein (CREB) regulated transcription coactivator3 (CRTC3) protects tumor cells from drug induced ferroptosiis and is a significant resister of IFN-γ treatment in hepatocellular car-cinoma (HCC). Mechanically, CRTC3 knockout alters tumor cell lipid pattern and increases the abundance of polyunsaturated fatty acids (PUFAs), which facilitates lipid peroxidation and renders HCC cells susceptible to ferroptosis inducers. To scavenge accumulated lipid peroxides (LPO) and maintain redox equilibrium, HCC cells upregulate SLC7A11 expression to enhance the activity of glutamate-cystine antiporter (system xc-). As IFN-γ inhibiting system xc-, simultaneously treatment of IFN-γ disrupts the compensatory mechanism, and generates a synergistic effect with CRTC3 knockout to facilitate ferroptosis. The sensitizing effect of CRTC3 depletion was further confirmed in typical ferroptosis inducers including RSL3, Erastin and Sorafeinib. Here, we reported a hitherto unexpected role of CRTC3 in regulating PUFAs metabolism and ferroptosis. Targeting the CRTC3 signaling in combination with ferroptosis inducers may represent a viable approach to treat cancer and overcome drug resistance in HCC.