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

Cellular prion protein (PrP) 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 is prone to undergo liquid-liquid phase separation (LLPS). However, it remains unknown whether PrP contributes to LLPS-inducing cancer development. Herein, we observed an upregulation of PrP expression in hepatitis B virus-positive hepatocellular carcinoma (HCC). Subsequent investigation revealed that HBx of HBV enhances PrP expression in a dose-dependent manner by binding to CREB1. Furthermore, we demonstrated that PrP 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 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 is necessary for its LLPS and subsequent activation of the NF-κB signaling pathway. Additionally, our findings indicate that NF-κB activation by PrP condensates leads to increased IL-8 expression which further promotes tumor development.