PABPN1-C5 axis promotes hepatocellular carcinoma progression via NF-κB activation

RNA polyadenylation is a key post-transcriptional modification essential for gene expression regulation. However, the role and mechanism of polyadenylation and its key molecule, polyadenylate binding protein nuclear 1 (PABPN1), in hepatocellular carcinoma (HCC) remain poorly understood. This study investigates the role of PABPN1 and its regulatory genes in HCC progression to identify potential therapeutic targets. Analysis of The Cancer Genome Atlas (TCGA) dataset and an independent HCC cohort revealed significant upregulation of PABPN1 in HCC patients, which correlates with poor prognosis. Loss-of-function studies using HCC cell lines and conditional knockout mouse models demonstrated that targeting PABPN1 inhibited HCC progression. Conversely, overexpression of PABPN1 promoted HCC development in vitro and in a hydrodynamic transfection hepatocarcinogenesis mouse model. Mechanistic investigations showed that PABPN1 modulates C5 mRNA polyadenylation and stability, with the PABPN1-C5 axis driving NF-κB activation and recruiting polymorphonuclear myeloid-derived suppressor cells (PMN-MDSCs) to promote HCC progression. Therapeutic targeting of the PABPN1-C5 axis using the C5a receptor inhibitor CCX168 significantly inhibited HCC progression in both in vitro and in vivo models. This study identifies PABPN1 as a critical regulator of HCC development and sheds light on the post-transcriptional regulation of complement components in cancer. Targeting the PABPN1-C5 axis represents a promising strategy for HCC treatment.