Arsenic Trioxide Down-Regulate Epstein-Barr Virus Encoded Latent Membrane Protein-1 And Its Anticancer Activity In Nasopharyngeal Carcinoma Cells

Aims and background: It was demonstrated that nasopharyngeal carcinoma (NPC) is closely related to Epstein-Barr virus (EBV) infection and the virus encoded latent membrane protein-1 (LMP1) takes an important role in the pathogenesis of NPC, blocking differentiation and against apoptosis as well as promoting metastasis. In our preclinical study, As₂O₃ has been implicated as a promising anticancer agent in inducing apoptosis and differentiation of NPC xenografts in Scid mouse. However, whether the mechanism is involved in the repression of LMP1 remained unknown. Furthermore, the role of changes of LMP1 expression influenced by As₂O₃ in NPC cells in indicating apoptosis and invasion potential also need to be investigated. Therefore, the thesis consisting of two parts is designed to answer the above questions. In part one, the purpose is to study whether As₂O₃ can inhibit LMP1 expression in HNE1-LMP1 cells. Then, the cell telomere length alteration and apoptosis are detected in order to explore the role of LMPl inhibition in the apoptosis effect mediated by As₂O₃. The aim of the part two is to observe the metastasis potential of residual cells after treated by As₂O₃ and its possible mechanisms. The relationship between LMPl status and MMP9 was also analyzed in attempt to explore the role of LMPl in this procedure.Methods: Stable expression of LMP1-positive human NPC cell line HNE1-LMP1 and its parental LMP1-negative cell Line HNE1 were used as in vitro models. In the part one, HNE1-LMP1 cells (1 × 10⁵/mL) were cultured in the media containing varied concentration of As₂O₃ (0 1 2 3, 4 5 μ mol/L )for 48 hours, respectively. Western-blot and the laser scanning confocal microscopy were performed to observe the changes of latent membrane protein 1 (LMP1) expression. The level of mRNA was also detected by semi-quantitative reverse transcription-polymerase chain reaction...