Intricate relationship between IL-6, STAT3 activation and LMP1 in EBV-infected NPE cells.

<p>(A) A schematic diagram showing the positive feedback loop of IL-6 activation of STAT3 and LMP1 expression in EBV-infected cell. (B) NP460hTert-EBV, C666-1 and HONE-EBV cells were treated with IL-6 for 4 hours. Total RNA were extracted from treated and untreated cells and examined for mRNA expression levels of LMP1 by quantitative real-time (RT-PCR). Results were normalized to GAPDH. These results were computed from triplicates of individual experiments. * <i>p</i><0.05. (C) EBV-infected NP460hTert cells were stably transduced with STAT3-C or control vector. The mRNA expression levels of LMP1 were analyzed by quantitative RT-PCR. Results were normalized to GAPDH. * <i>p</i><<i>0.05</i>. (D) LMP1 expression was upregulated in NP460hTert-EBV cells after treating with IL-6 for 48 hours. (E) PLNSX-LMP1 vector and PLNSX control vector were introduced into CNE2 cells by retroviral infection. Both LMP1 expression and STAT3 phosphorylation in CNE2 cells were confirmed by Western blotting. (F) HONE1 and EBV-infected HONE1 cells were transiently co-transfected with m67 firefly luciferase reporter construct (luc-m67) in conjunction with a Renilla luciferase vector and STAT3-C plasmid or control plasmid. Cell lysates were assessed for luciferase activity 36 hours after transfection. Relative luciferase activity was calculated by normalizing the firefly luciferase activity to Renilla luciferase activity. These results were computed from triplicate separate experiments. * <i>p</i><0.05 ^#<i>p</i><0.05. (G) HONE1 cells were transiently co-transfected with IL-6 firefly luciferase reporter construct (pGL3-IL-6-Luc) in conjunction with a Renilla luciferase vector and pcDNA3/2117-LMP1 or control vector. These results were computed from triplicate separate experiments. * <i>p</i><0.05.