PF-429242 exhibits anticancer activity in hepatocellular carcinoma cells via FOXO1-dependent autophagic cell death and IGFBP1-dependent anti-survival signaling

Effective therapies for hepatocellular carcinoma (HCC) are urgently needed, as it is a type of cancer resistant to chemotherapy. Recent evidence showed that PF-429242, a membrane-bound transcription factor site-1 protease (MBTPS1) inhibitor, exhibited anticancer activities against glioblastomas, renal cell carcinoma, and pancreatic cancer. However, its anticancer activity against HCC has yet to be investigated. In this study, we found that PF-429242 induced autophagy-dependent cell death in HCC cells. RNA-sequencing analysis indicated that the primary effect of PF-429242 was inhibition of the sterol regulatory element-binding protein (SREBP) signaling pathway. However, overexpression of SREBP proteins did not efficiently rescue PF-429242-induced autophagy and cell death. Mechanistically, PF-429242 induced forkhead box protein O1 (FOXO1)-dependent autophagic cell death. Additionally, PF-429242 caused FOXO1-independent upregulation of insulin-like growth factor-binding protein 1 (IGFBP1), ultimately leading to autophagy-independent cell death. The in vivo anticancer activity of PF-429242 against HCC cells was demonstrated in a tumor xenograft mouse model. Therefore, PF-429242 is a potential anticancer agent to treat HCC by triggering FOXO1-dependent autophagic cell death and IGFBP1-mediated anti-survival signaling in parallel.