Bleomycin induced EBV-specific gastric epithelial cell death is enhanced by LMP2A

Abstract

Epstein-Barr virus (EBV) infects more than 90% of the global population, leading to EBV-related cancers, such as EBV-associated gastric cancer and nasopharyngeal carcinoma. Despite the rarity of p53 mutations in tumor cells, there is a lack of specific therapies targeting EBV-associated gastric cancers. Our study demonstrated that EBV-infected gastric epithelial cells exhibited high sensitivity to the bleomycin family, encompassing bleomycin and zeocin, compared to uninfected cells. Zeocin treatment induces a DNA damage response (DDR) and promotes the expression of BZLF1, triggering the expression of EBV lytic genes. This cascade leads to apoptosis via a p53 dependent pathway, coinciding with the activation of caspase-3. Cells infected with the BZLF1-deficient virus could not induce apoptosis by zeocin treatment, and the cells maintained a tight latent infection but initiated a robust DDR. Conversely, neither lytic infection nor DDR was induced by zeocin treatment in cells infected with LMP2A-deficient virus. These findings indicate that LMP2A augments DDR in EBV-infected gastric epithelial cells, facilitating the transition from latent to lytic infection, and consequently inducing cell death. Bleomycin derivatives are expected to serve as fundamental components in the development of specific anticancer drugs targeting EBV-positive epithelial cancer cells. IMPORTANCEBecause of its ubiquitous infection in the human population, the number of patients suffering from EBV-related diseases, including malignant tumors and severe active infections, is substantial. Previous research has reported the potential of drugs such as HDAC inhibitors and poly ADP-ribose polymerase inhibitors to induce cell death in EBV-infected cells. However, a clinical therapeutic agent specifically reducing EBV-infected cells has not yet been available. In this study, we report that bleomycin, or its derivative, which has been used for over half a century, induces apoptotic cell death in EBV-infected cells by triggering lytic viral replication associated with DNA damage response. Particularly, we discovered that the viral latent gene LMP2A unexpectedly enhances bleomycin-induced EBV-infected epithelial cell death by promoting DDR.