Background & Aims Hepatitis B surface antigen (HBsAg) has been identified to increase the risk and
contribute to hepatocellular carcinoma (HCC). However, factors and mechanisms that
drive HBsAg-induced hepatocarcinogenesis remain poorly defined, thus hindering the
development of new therapeutic strategies.
Methods Data mining of the microarray set GSE84429 indicated the potential candidate signatures
of HBsAg-driven intracellular events. Hemizygous tg(Alb1HBV)44Bri/J mice were investigated
for this HBsAg-driven carcinogenesis by western blotting, immunohistochemical and
immunofluorescence staining. Finally, the findings were verified by HBsAg overexpression
in Hepa1-6 cell line. Functional analysis was performed to study the contribution
of these events.
Results Gene set enrichment analysis suggested signatures in HBsAg-transgenic mice correlated
with endoplasmic reticulum (ER) stress, unfolded protein response (UPR), autophagy,
cell cycle and proliferation. These events were investigated in 2-, 8- and 12-month-old
HBsAg-transgenic mice. In HBsAg-transgenic mice the UPR was induced. Interestingly,
our study indicates that HBsAg impaired the autophagic flux. In HBsAg-transgenic mice
autophagy was enhanced at the early stage (increased Beclin1) and blocked at the late
stage (increased p62 and LC3B-II). These findings were verified in HBsAg-overexpressing
Hepa1-6. In addition, HBsAg changed lysosomal acidification, visualized by acridine
orange staining and promoted proliferation, indicated by CCK-8 staining and colony
formation assay.
Conclusion Our findings revealed the HBsAg directly induces ER stress, impairs autophagy and
promotes proliferation thereby driving hepatocarcinogenesis. Moreover, this study
expanded the understanding of HBsAg-mediated intracellular events in carcinogenesis.
