Silencing progestagen-associated endometrial protein (PAEP) suppresses sorafenib resistance and enhances sorafenib-induced ferroptosis in hepatocellular carcinoma.

[BACKGROUND AND AIMS] As a ferroptosis inducer, sorafenib, a first-line treatment for hepatocellular carcinoma (HCC), has a significant antitumor effect. Nonetheless, HCC patients frequently develop sorafenib resistance. Here, we investigated the impacts of progestagen-associated endometrial protein (PAEP), which controls sorafenib resistance and tumorigenesis in HCC. Furthermore, we investigated the function of PAEP and the underlying molecular mechanisms that cause HCC ferroptosis when sorafenib is applied.

[METHODS] Western blot analysis, cell proliferation, colony formation and animal experiments were performed to investigate the function of PAEP in sorafenib resistance and tumorigenesis in HCC. We detected the levels of reactive oxygen species, iron, and malondialdehyde and preformed transmission electron microscopy to investigate the relationship between PAEP and ferroptosis. Co-immunoprecipitation (co-IP) assay was performed to investigate the underlying molecular mechanisms of PAEP that cause HCC ferroptosis.

[RESULTS] PAEP was significantly overexpressed in HCC tissues, and this was associated with a poor clinical prognosis. PAEP silencing dramatically reduced HCC cells' malignant phenotype. We found that sorafenib-induced ferroptosis was more sensitive to HCC cells with PAEP knockdown. Furthermore, the orthotopic cell line-derived xenograft mouse model results showed that sorafenib sensitivity can be effectively increased by PAEP knockdown. We determined that transferrin (TF) was a PAEP target using the String database, and we further supported this finding with Co-IP analysis. Additionally, on sorafenib-induced ferroptosis in HCC cells, TF partially reversed the effects of PAEP knockdown.

[CONCLUSIONS] Our research indicates that PAEP may be a potential biomarker for predicting sorafenib resistance in HCC and disruption of PAEP expression may be a potential cancer-directed therapeutic option for HCC.