RETRACTED ARTICLE: Activation of PERK-Nrf2 oncogenic signaling promotes Mdm2-mediated Rb degradation in persistently infected HCV culture

Yucel Aydin,Srinivas Chava,Shuanghu Liu,Milad Chedid,Srikanta Dash,Suchitra Sumitran-Holgersson,Curt H Hagedorn,Hua Lu,Luis A Balart,Donkita Danielle Williams,Krzysztof Moroz,Krzysztof Reiss

doi:10.1038/s41598-017-10087-6

Abstract

The mechanism of how chronic hepatitis C virus (HCV) infection leads to such a high rate of hepatocellular carcinoma (HCC) is unknown. We found that the PERK axis of endoplasmic reticulum (ER) stress elicited prominent nuclear translocation of Nrf2 in 100% of HCV infected hepatocytes. The sustained nuclear translocation of Nrf2 in chronically infected culture induces Mdm2-mediated retinoblastoma protein (Rb) degradation. Silencing PERK and Nrf2 restored Mdm2-mediated Rb degradation, suggesting that sustained activation of PERK/Nrf2 axis creates oncogenic stress in chronically infected HCV culture model. The activation of Nrf2 and its nuclear translocation were prevented by ER-stress and PERK inhibitors, suggesting that PERK axis is involved in the sustained activation of Nrf2 signaling during chronic HCV infection. Furthermore, we show that HCV clearance induced by interferon-α based antiviral normalized the ER-stress response and prevented nuclear translocation of Nrf2, whereas HCV clearance by DAAs combination does neither. In conclusion, we report here a novel mechanism for how sustained activation of PERK axis of ER-stress during chronic HCV infection activates oncogenic Nrf2 signaling that promotes hepatocyte survival and oncogenesis by inducing Mdm2-mediated Rb degradation.

Highlights

A The sustained nuclear translocation of Nrf[2] in chronically infected culture induces Mdm2-mediated retinoblastoma protein (Rb) degradation
We show that chronic endoplasmic reticulum (ER)-stress/unfolded protein response (UPR) response during persistent hepatitis C virus (HCV) infection resulted in activation of Nrf[2] and its nuclear translocation being mediated by protein kinase-like endoplasmic reticulum kinase (PERK) axis of the UPR
Our results suggest that persistent HCV infection induces NF-E2 related factor 2 (Nrf2)/antioxidant response elements (ARE) dependent expression of oncoprotein Mdm[2] for cell survival

Summary

E Materials and Methods

PHHs were obtained from XenoTech LLC, Kansas City, MO, and cultured with hepatocyte culture media supplemented with 10% human serum (Invitrogen, Brown Deer, WI). After 18 hours of infection, hepatocytes were replaced with fresh hepatocyte culture media (XenoTech, LLC, Kansas City, MO) supplemented with 10% human serum Uninfected or infected PHHs were harvested every 3 days and cell pellets were used for RNA isolation and Western blot analysis. The oxidation-reduction potential of HCV infected culture supernatants at day 12 was compared with uninfected cell supernatants using a novel galvanostat-based technology The number of GFP expressing cells in the HCV infected Huh-7.5 cells were determined by flow cytometry using a BD FACSCalibur machine (BD Bioscience).

Results

D Acknowledgements

C Author Contributions