COMMD10 inhibits HIF1α/CP loop to enhance ferroptosis and radiosensitivity by disrupting Cu-Fe balance in hepatocellular carcinoma.

BACKGROUND & AIMS: Copper (Cu) is an essential trace element whose serum levels have been reported to act as an effective indicator of the efficacy of radiotherapy. However, little is known about the role of Cu in radiotherapy. In this study we aimed to determine this role and investigate the precise mechanism by which Cu or Cu-related proteins regulate the radiosensitivity of hepatocellular carcinoma (HCC). METHODS: The expression and function of Cu and copper metabolism MURR1 domain 10 (COMMD10) were assessed via a Cu detection assay, immunostaining, real-time PCR, western blot, a radiation clonogenic assay and a 5-ethynyl-2'-deoxyuridine assay. Ferroptosis was determined by detecting glutathione, lipid peroxidation, malondialdehyde and ferrous ion (Fe) levels. The in vivo effects of Cu and COMMD10 were examined with Cu/Cu chelator treatment or lentivirus modification of COMMD10 expression in radiated mouse models. RESULTS: We identified a novel role of Cu in promoting the radioresistance of HCC cells. Ionizing radiation (IR) induced a reduction of COMMD10, which increased intracellular Cu and led to radioresistance of HCC. COMMD10 enhanced ferroptosis and radiosensitivity in vitro and in vivo. Mechanistically, low expression of COMMD10 induced by IR inhibited the ubiquitin degradation of HIF1α (by inducing Cu accumulation) and simultaneously impaired its combination with HIF1α, promoting HIF1α nuclear translocation and the transcription of ceruloplasmin (CP) and SLC7A11, which jointly inhibited ferroptosis in HCC cells. In addition, elevated CP promoted HIF1α expression by reducing Fe, forming a positive feedback loop. CONCLUSIONS: COMMD10 inhibits the HIF1α/CP loop to enhance ferroptosis and radiosensitivity by disrupting Cu-Fe homeostasis in HCC. This work provides new targets and treatment strategies for overcoming radioresistance in HCC. LAY SUMMARY: Radiotherapy benefits patients with unresectable or advanced hepatocellular carcinoma (HCC), but its effectiveness is hampered by radioresistance. Herein, we uncovered a novel role for copper in promoting the radioresistance of HCCs. This work has revealed new targets and potential treatment strategies that could be used to sensitize HCC to radiotherapy.