Abstract 5756: Effects of Epstein-Barr virus latent membrane protein 1 (LMP1) on cell invasiveness and expression of endogenous microRNAs in human cells in vitro
Authors: Müller-Coan Bárbara Grasiele , Cesarman Ethel , Oliveira Deilson Elgui De 
Published: July 2017

Infection by the Epstein-Barr virus (EBV) is associated with a variety of human cancers, notably Burkitt lymphoma and nasopharyngeal carcinoma (NPC). Most malignant cells within EBV-associated cancers are latently infected, and some viral products expressed during the latent phase of the viral cycle have well-described carcinogenicity, including the EBV latent membrane protein 1 (LMP1). Distinct viral genotypes described so far include the B95.8, the most studied viral strain originally found in an elderly patient with transfusion-induced infectious mononucleosis, and the M81 strain, isolated from a NPC case from a Chinese patient. Compared to B95.8, the EBV M81 strain infects epithelial cells more readily, and it is more likely to induce spontaneous viral lytic reactivation. However, whether these EBV strains have distinct biological features relevant for the progression of EBV-associated cancers remains to be elucidated. Thus, this study aimed to evaluate whether the expression of B95.1 and M81 variants of EBV LMP1 have different impact on cell migration and invasiveness of human cells lines in vitro, as well as on the expression of selected endogenous microRNAs (miRs) that were previously reported to have a role on cancer progression. Expression of EBV LMP1 was achieved in 293 and NP69 cells transfected with vectors encoding its B95.8 or M81 variants. In vitro migration and invasion rates were assessed by the scratch wound healing assay and the Boyden chamber assay, respectively. The expression of 91 selected miRs were evaluated by a customized qPCR-array approach. Cells expressing EBV LMP1 showed increased migration and invasion rates compared with mock-transfected cells. However, the differences observed between B95.8 and M81 variants did not achieve statistical significance. Conversely, 293 cells expressing the M81 variant of LMP1 showed hyperexpression of human miRs 497-5p, 17-3p, and 34a-5p, compared to B95.8. The in silico target prediction for these miRs showed enrichment of gene targets involved in the MAPK, NF-κB, and PI3K/AKT intracellular signaling pathways. This would reflect in negative regulation of cell proliferation and cell motility/adhesion, as well as higher levels of apoptosis. Based on these data, it is plausible to suggest that EBV LMP1 from M81 viral strain is somewhat less effective in terms of carcinogenicity, and this might be a reflect of the improved ability of EBV M81 to induce lytic viral infection compared to the B95.8 strain, as previously reported. In conclusion, the results indicate that cells expressing LMP1 from EBV isolates B95.8 and M81 showed differences in terms of miR expression signatures, which ultimately might impact the pathogenesis and progression of EBV-associated cancers.

Citation Format: Bárbara Grasiele Müller-Coan, Ethel Cesarman, Deilson Elgui De Oliveira. Effects of Epstein-Barr virus latent membrane protein 1 (LMP1) on cell invasiveness and expression of endogenous microRNAs in human cells in vitro [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2017; 2017 Apr 1-5; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2017;77(13 Suppl):Abstract nr 5756. doi:10.1158/1538-7445.AM2017-5756