Triterpenoids抑制Epstein-Barr virus進入溶裂循環

Abstract

Epstein-Barr virus (EBV) is a human herpesvirus, which has two different life cycles: latent and lytic. EBV infects lymphoid and epithelial cells. Infection by this virus causes infectious mononucleosis and is closely related to several malignant diseases, including Burkitt’s lymphoma, T-cell lymphoma, Hodgkin’s disease，gastric cancer and nasopharyngeal carcinoma. At the onset of the EBV lytic cycle, the virus expresses two immediate-early genes, BRLF1 and BZLF1, which encode transcription factors, Rta and Zta, respectively. These two transcription factors are required to activate the EBV early genes and lytic cascade. Clinically effective anti-EBV drugs that target EBV-encoded DNA polymerase, including acyclovir, ganciclovir and indolocarbazole, are commonly used for inhibiting the lytic cycle of EBV. However, viruses are potentially mutagenic for resistance to drugs. In light of this, it is necessary to identify new targets for antivirus chemotherapy and to develop new treatment strategies. Triterpenoids are formed from six isoprene units with 30 carbons. As it is generally known, triterpenoids are major constituents in several herbal remedies or fungi that are reported to have the capacity of anti-inflammatory, anticancer, repressing cell proliferation, inducing cell apotosis program, etc. The purpose of this study is to demonstrate the effect of JYKMA-37, one of the derivatives of triterpenoids, on repressing the EBV lytic cycle. First of all, P3HR1 cells were treated with different concentrations of JYK-MA-37, and then induced the EBV lytic cycle by sodium butyrate (SB) and 12-O-tetradecanoylphorbol-13-acetate (TPA). Immunoblot analysis and flow cytometry analysis were performed, the results showed that JYK-MA-37 at 10 μM effectively inhibits the expression of EBV lytic protein, including Rta、Zta and EA-D, after lytic induction in P3HR1 cells (EC50 = 22.083 μM，CC50 = 11.32 μM). Moreover, transient transfection analysis revealed that transactivation of BRLF1 promoter (Rp) and BZLF1 promoter (Zp) were inhibited by JYK-MA-37 in a dose-dependent manner. Finally, real-time PCR showed that JYK-MA-37 substantially reduces the numbers of EBV particles produced by the cells after lytic induction. Taken together, this study demonstrated that JYK-MA-37 poccess the capacity of inhibiting the progression of EBV lytic cycle.