Upregulated PrPC by HBx enhances NF-κB signal via liquid–liquid phase separation to advance liver cancer

Cellular prion protein (PrP^C) has been implicated in carcinogenic through the activation of various signal pathways, however, the precise mechanisms remain elusive. In vitro studies have shown that PrP^C is prone to undergo liquid-liquid phase separation (LLPS). However, it remains unknown whether PrP^C contributes to LLPS-inducing cancer development. Herein, we observed an upregulation of PrP^C expression in hepatitis B virus-positive hepatocellular carcinoma (HCC). Subsequent investigation revealed that HBx of HBV enhances PrP^C expression in a dose-dependent manner by binding to CREB1. Furthermore, we demonstrated that PrP^C undergoes LLPS and recruits TRAF2/6, TAB2/3, and TAK1 protein, thereby activating the NF-κB signaling pathway and promoting tumor progression. Notably, although unable to undergo LLPS itself, the α3 helix of PrP^C is essential for its activation of the NF-κB signaling pathway during the LLPS process. Further analysis unveiled that disulfide bond formation within the C-terminal domain of PrP^C is necessary for its LLPS and subsequent activation of the NF-κB signaling pathway. Additionally, our findings indicate that NF-κB activation by PrP^C condensates leads to increased IL-8 expression which further promotes tumor development.