Inhibition of autophagy in EBV-positive Burkitt's lymphoma cells enhances EBV lytic genes expression and replication.
Autophagy, an important degradation system involved in maintaining cellular homeostasis, serves also to eliminate pathogens and process their fragments for presentation to the immune system. Several viruses have been shown to interact with the host autophagic machinery to suppress or make use of this cellular catabolic pathway to enhance their survival and replication. Epstein Barr virus (EBV) is a γ-herpes virus associated with a number of malignancies of epithelial and lymphoid origin in which establishes a predominantly latent infection. Latent EBV can periodically reactivate to produce infectious particles that allow the virus to spread and can lead to the death of the infected cell. In this study, we analyzed the relationship between autophagy and EBV reactivation in Burkitt's lymphoma cells. By monitoring autophagy markers and EBV lytic genes expression, we demonstrate that autophagy is enhanced in the early phases of EBV lytic activation but decreases thereafter concomitantly with increased levels of EBV lytic proteins. In a cell line defective for late antigens expression, we found an inverse correlation between EBV early antigens expression and autophagosomes formation, suggesting that early after activation, the virus is able to suppress autophagy. We report here for the first time that inhibition of autophagy by Bafilomycin A1 or shRNA knockdown of Beclin1 gene, highly incremented EBV lytic genes expression as well as intracellular viral DNA and viral progeny yield. Taken together, these findings indicate that EBV activation induces the autophagic response, which is soon inhibited by the expression of EBV early lytic products. Moreover, our findings open the possibility that pharmacological inhibitors of autophagy may be used to enhance oncolytic viral therapy of EBV-related lymphomas.
Department of Public Health and Infectious Diseases, Sapienza University of Rome, 00185 Rome, Italy.
A
A
De Leo
Department of Public Health and Infectious Diseases, Sapienza University of Rome, 00185 Rome, Italy.
F
F
Colavita
National Institute for Infectious Diseases "Lazzaro Spallanzani" IRCCS, 00149 Rome, Italy.
F
F
Ciccosanti
National Institute for Infectious Diseases "Lazzaro Spallanzani" IRCCS, 00149 Rome, Italy.|Department of Biological and Environmental Sciences and Technologies (DiSTeBA), University of Salento, 73100 Lecce, Italy.
G M
GM
Fimia
The Wistar Institute, Philadelphia, PA, USA.
P M
PM
Lieberman
Department of Public Health and Infectious Diseases, Sapienza University of Rome, 00185 Rome, Italy.
E
E
Mattia
D001343:Autophagy / Q000235:genetics*; D002051:Burkitt Lymphoma / Q000235:genetics*; D045744:Cell Line, Tumor; D004261:DNA Replication; D015870:Gene Expression; D006801:Humans; D015151:Immunoblotting; D014779:Virus Replication / Q000235:genetics*