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

Abstract

Oxaliplatin (OXA) resistance is a major clinic challenge in hepatocellular carcinoma (HCC). Ferroptosis is a kind of iron‐dependent cell death. Triggering ferroptosis is considered to restore sensitivity to chemotherapy. In the present study, we found that USP20 was overexpressed in OXA‐resistant HCC cells. High expression of USP20 in HCC was associated with poor prognosis. USP20 contributes OXA resistance and suppress ferroptosis in HCC. Pharmacological inhibition or knockdown of USP20 triggered ferroptosis and increased the sensitivity of HCC cells to OXA both in vitro and in vivo. Coimmunoprecipitation results revealed that the UCH domain of USP20 interacted with the N terminal of SLC7A11. USP20 stabilized SLC7A11 via removing K48‐linked polyubiquitination of SLC7A11 protein at K30 and K37. Most importantly, DNA damage‐induced ATR activation was required for Ser132 and Ser368 phosphorylation of USP20. USP20 phosphorylation at Ser132 and Ser368 enhanced its stability and thus conferred OXA and ferroptosis resistance of HCC cells. Our study reveals a previously undiscovered association between OXA and ferroptosis and provides new insight into mechanisms regarding how DNA damage therapies always lead to therapeutic resistance. Therefore, targeting USP20 may mitigate the development of drug resistance and promote ferroptosis of HCC in patients receiving chemotherapy.

Protein modification and degradation in ferroptosis

“…These complex regulatory mechanisms have a context-dependent impact on the progression of ferroptosis-mediated conditions, such as hepatic fibrosis, colorectal cancer, breast cancer, and hepatocellular carcinoma. Conversely, the deubiquitinating enzymes OTUB1 and ubiquitin specific peptidase 20 (USP20) mediate the deubiquitination of SLC7A11, thereby stabilizing SLC7A11 levels in cancer cells [ 6 , 122 ]. Additionally, hepatocellular carcinoma ferroptosis associative lncRNA (HEPFAL) accelerates ferroptosis in hepatocellular carcinoma cells, whereas lncRNA LINC00578 inhibits ferroptosis by modulating the ubiquitination of SLC7A11 in pancreatic cancer cells [ 123 , 124 ].…”