Hepatitis B surface antigen induces endoplasmic reticulum stress, impairs autophagy and promotes proliferation, thereby driving hepatocarcinogenesis

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.

Publikationsverlauf

Artikel online veröffentlicht:
26. Januar 2022