Development Of EBV-related Tumors Research Articles

EBV-miR-BART12 accelerates migration and invasion in EBV-associated cancer cells by targeting tubulin polymerization-promoting protein 1.

Epstein-Barr virus (EBV) infection leads to cancers with an epithelial origin, such as nasopharyngeal cancer and gastric cancer, as well as multiple blood cell-based malignant tumors, such as lymphoma. Interestingly, EBV is also the first virus found to carry genes encoding miRNAs. EBV encodes 25 types of pre-miRNAs which are finally processed into 44 mature miRNAs. Most EBV-encoded miRNAs were found to be involved in the occurrence and development of EBV-related tumors. However, the function of EBV-miR-BART12 remains unclear. The findings of the current study revealed that EBV-miR-BART12 binds to the 3'UTR region of Tubulin Polymerization-Promoting Protein 1 (TPPP1) mRNA and downregulates TPPP1, thereby promoting the invasion and migration of EBV-related cancers, such as nasopharyngeal cancer and gastric cancer. The mechanism underlying this process was found to be the inhibition of TPPP1 by EBV-miRNA-BART12, which, in turn, inhibits the acetylation of α-tubulin, and promotes the dynamic assembly of microtubules, remodels the cytoskeleton, and enhances the acetylation of β-catenin. β-catenin activates epithelial to mesenchymal transition (EMT). These two processes synergistically promote the invasion and metastasis of tumor cells. To the best of our knowledge, this is the first study to reveal the role of EBV-miRNA-BART12 in the development of EBV-related tumors as well as the mechanism underlying this process, and suggests potential targets and strategies for the treatment of EBV-related tumors.

Targeting Epstein-Barr virus oncoprotein LMP1-mediated high oxidative stress suppresses EBV lytic reactivation and sensitizes tumors to radiation therapy.

Generating oxidative stress is a critical mechanism by which host cells defend against infection by pathogenic microorganisms. Radiation resistance is a critical problem in radiotherapy against cancer. Epstein-Barr virus (EBV) is a cancer-causing virus and its reactivation plays an important role in the development of EBV-related tumors. This study aimed to explore the inner relationship and regulatory mechanism among oxidative stress, EBV reactivation, and radioresistance and to identify new molecular subtyping models and treatment strategies to improve the therapeutic effects of radiotherapy.Methods: ROS, NADP+/NADPH, and GSSG/GSH were detected to evaluate the oxidative stress of cells. 8-OHdG is a reliable oxidative stress marker to evaluate the oxidative stress in patients. Its concentration in serum was detected using an ELISA method and in biopsies was detected using IHC. qPCR array was performed to evaluate the expression of essential oxidative stress genes. qPCR, Western blot, and IHC were used to measure the level of EBV reactivation in vitro and in vivo. A Rta-IgG ELISA kit and EBV DNA detection kit were used to analyze the reactivation of EBV in serum from NPC patients. NPC tumor tissue microarrays was used to investigate the prognostic role of oxidative stress and EBV reactivation. Radiation resistance was evaluated by a colony formation assay. Xenografts were treated with NAC, radiation, or a combination of NAC and radiation. EBV DNA load of tumor tissue was evaluated using an EBV DNA detection kit. Oxidative stress, EBV reactivation, and the apoptosis rate in tumor tissues were detected by using 8-OHdG, EAD, and TUNEL assays, respectively.Results: We found that EBV can induce high oxidative stress, which promotes its reactivation and thus leads to radioresistance. Basically, EBV caused NPC cells to undergo a process of 'Redox Resetting' to acquire a new redox status with higher levels of ROS accumulation and stronger antioxidant systems by increasing the expression of the ROS-producing enzyme, NOX2, and the cellular master antioxidant regulator, Nrf2. Also, EBV encoded driving protein LMP1 promotes EBV reactivation through production of ROS. Furthermore, high oxidative stress and EBV reactivation were positively associated with poor overall survival of patients following radiation therapy and were significant related to NPC patients' recurrence and clinical stage. By decreasing oxidative stress using an FDA approved antioxidant drug, NAC, sensitivity of tumors to radiation was increased. Additionally, 8-OHdG and EBV DNA could be dual prognostic markers for NPC patients.Conclusions: Oxidative stress mediates EBV reactivation and leads to radioresistance. Targeting oxidative stress can provide therapeutic benefits to cancer patients with radiation resistance. Clinically, we, for the first time, generated a molecular subtyping model for NPC relying on 8-OHdG and EBV DNA level. These dual markers could identify patients who are at a high risk of poor outcomes but who might benefit from the sequential therapy of reactive oxygen blockade followed by radiation therapy, which provides novel perspectives for the precise treatment of NPC.

Epstein–Barr virus miR-BART3-3p promotes tumorigenesis by regulating the senescence pathway in gastric cancer

Epstein-Barr virus-associated gastric cancer (EBVaGC) accounts for about 10% of all gastric cancer cases and has unique pathological and molecular characteristics. EBV encodes a large number of microRNAs, which actively participate in the development of EBV-related tumors. Here, we report that EBV-miR-BART3-3p (BART3-3p) promotes gastric cancer cell growth in vitro and in vivo Moreover, BART3-3p inhibits the senescence of gastric cancer cells induced by an oncogene (RASG12V) or chemotherapy (irinotecan). LMP1 and EBNA3C encoded by EBV have also been reported to have antisenescence effects; however, in EBVaGC specimens, LMP1 expression is very low, and EBNA3C is not expressed. BART3-3p inhibits senescence of gastric cancer cells in a nude mouse model and inhibits the infiltration of natural killer cells and macrophages in tumor by altering the senescence-associated secretory phenotype (SASP). Mechanistically, BART3-3p directly targeted the tumor suppressor gene TP53 and caused down-regulation of p53's downstream target, p21. Analysis from clinical EBVaGC samples also showed a negative correlation between BART3-3p and TP53 expression. It is well known that mutant oncogene RASG12V or chemotherapeutic drugs can induce senescence, and here we show that both RASG12V and a chemotherapy drug also can induce BART3-3p expression in EBV-positive gastric cancer cells, forming a feedback loop that keeps the EBVaGC senescence at a low level. Our results suggest that, although TP53 is seldom mutated in EBVaGC, its expression is finely regulated such that EBV-encoded BART3-3p may play an important role by inhibiting the senescence of gastric cancer cells.

Abstract 277: Multiplex Epstein-Barr virus (EBV) serology in EBV-positive and -negative gastric cancer

Abstract BACKGROUND: The leading cause of gastric cancer is chronic Helicobacter pylori infection. However, about 10% of these tumors also contain monoclonal Epstein-Barr virus (EBV), associated with clinicopathologic differences from EBV-negative tumors. While the vast majority of the world's population is latently infected with EBV, viral reactivation is postulated to predispose to development of EBV-related tumors. To evaluate the association of EBV reactivation with EBV-positive gastric cancer, we compared anti-viral antibody profiles in subjects with EBV-positive and -negative gastric cancer using pretreatment serum samples from the U.S. National Cancer Institute's International EBV-Gastric Cancer Consortium. METHODS: This study included 54 EBV-positive and 90 EBV-negative gastric cancer cases. A multiplex serology assay based on fluorescent polystyrene bead technology was used to measure IgG antibodies to four EBV proteins expressed in lytic and/or latent infection: BamH1 Z EBV Replication Activator (ZEBRA), early antigen D (EAD), viral capsid p18 (VCAp18) and nuclear antigen 1 (EBNA1). To account for within-population clustering, multi-level logistic regression models were used to estimate odds ratios (OR) adjusted for distributions of sex (76% male), age (mean 57 years), anatomic subsite (14% cardia, 66% noncardia, and 20% overlapping or unspecified) and year of diagnosis (1994-2013). RESULTS: Antibody titers against ZEBRA and EAD were significantly associated with EBV-positive gastric cancer in unadjusted analyses. We found significantly elevated ORs for higher antibody titers against ZEBRA (9.9 for tertile 2 and 15 for tertile 3 vs. tertile 1; p-trend <0.001) and EAD (2.3 for tertile 2 and 12 for tertile 3; p-trend <0.001) in patients with EBV-positive tumors as compared to EBV-negative cases, adjusted for the possible confounders. Distribution of antibody titers against VCAp18 and EBNA1 were similar among tumor groups. CONCLUSIONS: These data indicate viral reactivation in patients with EBV-positive gastric cancer, supporting the hypothesis that EBV infection may contribute to cancer development. Our results further implicate the virus as a co-factor in gastric carcinogenesis, and may provide a useful diagnostic marker. Citation Format: M. Constanza Camargo, Angelika Michel, Kyoung-Mee Kim, Keitaro Matsuo, Linda M. Liao, Javier Torres, Jovanny Zabaleta, Margaret L. Gulley, Yasushi Yatabe, Isabel Alvarado-Cabrero, Jolanta Lissowska, Sung Kim, Michael Pawlita, Charles S. Rabkin. Multiplex Epstein-Barr virus (EBV) serology in EBV-positive and -negative gastric cancer. [abstract]. In: Proceedings of the 105th Annual Meeting of the American Association for Cancer Research; 2014 Apr 5-9; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2014;74(19 Suppl):Abstract nr 277. doi:10.1158/1538-7445.AM2014-277