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New Insights from Elucidating the Role of LMP1 in Nasopharyngeal Carcinoma.

ABSTRACT: Latent membrane protein 1 (LMP1) is an Epstein-Barr virus (EBV) oncogenic protein that has no intrinsic enzymatic activity or sequence homology to cellular or viral proteins. The oncogenic potential of LMP1 has been ascribed to pleiotropic signaling properties initiated through protein-protein interactions in cytosolic membrane compartments, but the effects of LMP1 extend to nuclear and extracellular processes. Although LMP1 is one of the latent genes required for EBV-immortalization of B cells, the biology of LMP1 in the pathogenesis of the epithelial cancer nasopharyngeal carcinoma (NPC) is more complex. NPC is prevalent in specific regions of the world with high incidence in southeast China. The epidemiology and time interval from seroconversion to NPC onset in adults would suggest the involvement of multiple risk factors that complement the establishment of a latent and persistent EBV infection. The contribution of LMP1 to EBV pathogenesis in polarized epithelia has only recently begun to be elucidated. Furthermore, the LMP1 gene has emerged as one of the most divergent sequences in the EBV genome. This review will discuss the significance of recent advances in NPC research from elucidating LMP1 function in epithelial cells and lessons that could be learned from mining LMP1 sequence diversity.

SUBMITTER: Shair KHY

PROVIDER: S-EPMC5923341 | biostudies-literature |

REPOSITORIES: biostudies-literature

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Epstein-Barr virus-encoded LMP1 regulated Pim1 kinase expression promotes nasopharyngeal carcinoma cells proliferation.

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Targeting Epstein-Barr virus oncoprotein LMP1-mediated glycolysis sensitizes nasopharyngeal carcinoma to radiation therapy.

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| S-EPMC4162460 | biostudies-literature

Targeting EBV-LMP1 DNAzyme enhances radiosensitivity of nasopharyngeal carcinoma cells by inhibiting telomerase activity.

Project description:The latent membrane protein 1 (LMP1), which is encoded by the Epstein-Barr virus (EBV), has been suggested to be one of the major oncogenic factors in nasopharyngeal carcinoma (NPC). In previous studies, we experimentally demonstrated that downregulation of LMP1 expression by targeting EBV-LMP1 DNAzyme (Dz1) could increase the radiosensitivity of NPC. However, how Dz1 contributes to the radiosensitivity in NPC is still not clear. In the present study, we confirmed that Dz1 decreases LMP1 expression and downregulates the expression of the catalytic subunit of telomerase (hTERT), both at the protein and mRNA levels (P<0.01), and therefore, consequently inhibits telomerase activity (P<0.05) in LMP1-positive NPC cells. We also observed that LMP1 mediated Akt phosphorylation is involved in the regulation of hTERT expression and phosphorylation. After LMP1 and hTERT expression was silenced by Dz1 and hTERT-targeted siRNA, respectively, the radiosensitivity increased in CNE1-LMP1 cells (P<0.05). The inhibition was more significant after Dz1 treatment was combined with siRNA (P<0.01). We concluded that hTERT expression and phosphorylation could be regulated by LMP1 through the Akt pathway, and Dz1 enhances radiosensitivity of LMP1-positive NPC cells by inhibiting telomerase activity.

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