Activation of the iEκ enhancer and enhancement of the iEκ activity by LMP1 in human nasopharyngeal carcinoma cells. (A) Schematic diagram of human iEκ-containing DNA fragment used in these experiments. Position of the iEκ, the NF-κB and the AP-1 binding sites were shown. For simplicity, other protein-binding sites in the iEκ were not shown. (B) Insertion sites for the definite DNA fragment into the pGL3-α plasmid which contains the human immunoglobulin Iα promoter and the firefly luciferase reporter gene. (C) Comparison of the activities of iEκ in human nasopharyngeal carcinoma cell lines. Transient transfected the pα-iEκwt construct, pGL3-α or pGL3-Basic vector into HNE2 and HNE2-LMP1 cells and luciferase reporter assays were performed as described in Materials and methods. The relative luciferase activity normalized to the value of the internal control plasmid pRL-SV40 activity. Results were expressed as fold induction of pGL3-Basic activity, which was assigned a value of 1. The data represent the mean ± SD of the three independent experiments performed in triplicate. Statistical significance: # P < 0.01 vs. pGL3-α-transfected HNE2, *P < 0.01 vs. pGL3-α-transfected HNE2-LMP1. (D) Transient expression of LMP1 increased the iEκ activity in nasopharyngeal carcinoma cells. HNE2 cells were co-transfected with 400 ng/well of pα-iEκwt, pGL3-α or pGL3-Basic vector and 80 ng/well of internal control pRL-SV40 together with 200 ng/well of pSG5-LMP1 or blank expression plasmid pSG5 (total DNA ~800 ng). Cells were harvested at 36 h after transfection and subjected to luciferase analysis. Statistical significance: # P < 0.01 vs. pSG5-transfected HNE2.
Liu et al. Molecular Cancer 2009 8:92 doi:10.1186/1476-4598-8-92