Approximately 10% of all gastric cancer cases worldwide are associated with Epstein-Barr virus (EBV) infection. This subgroup differs from non-infected equivalents through a distinct mutational and epigenetic signature, which is crucial for the establishment and maintenance of the viral latent state. Disruption of the latent state and subsequent induction of the lytic cycle, called reactivation, can be used as a therapeutic strategy for this cancer type through either combination with antiviral agents or by induction of an EBV-specific immune response. In this study, epigenetic inhibitors were tested for their potential to reactivate EBV using a novel screening method based on the expression of Zebra, a key regulator of EBV reactivation. Histone deacetylase inhibitors (HDACis), more specifically benzamide-based HDACis, were the most potent group of reactivating agents in this screen. Those HDACis induced the expression of lytic cycle genes as well as targeted cell killing in combination with antiviral agents. Moreover, the reactivation through those agents was sufficient to activate cytotoxic T-cells and thereby ensured a supportive role of the immune system in targeted cell killing. In an additional screen, topoisomerase inhibitors and other chemotherapeutic agents showed synergistic effects on Zebra expression together with HDACis, which was linked to the induction of p53 expression through those compounds. While p53 is known to be involved in the expression of Zebra, the viral DNA processivity factor Ea-D and the viral DNA binding protein DNBI were identified as a potential novel binding protein of p53 and could thus point towards a novel role of p53 in EBV lytic replication. Taken together, this study identifies potential novel therapeutic compound combinations for the treatment of EBV-associated epithelial cancers that could be translated into the clinic after further assessment.
| Identifer | oai:union.ndltd.org:bl.uk/oai:ethos.bl.uk:757980 |
| Date | January 2018 |
| Creators | Zentelis, Stefanie |
| Contributors | Lu, Xin |
| Publisher | University of Oxford |
| Source Sets | Ethos UK |
| Detected Language | English |
| Type | Electronic Thesis or Dissertation |
| Source | http://ora.ox.ac.uk/objects/uuid:f6ca7eac-68ac-4c58-9b49-8cf3649a4f0f |
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