HPV16 E6 reduces E-cadherin protein expression by reducing E-cadherin promoter and transcript levels, independent of the major Epal repressor element and HDAC.

<p>(<b>a</b>) Levels of E-cadherin mRNA were determined by qRT-PCR analysis on RNA extracted from HCT116 control and HCT116 E6 cells. GAPDH mRNA was amplified in the same RNA samples for normalization. n = 5 independent experiments. (<b>b</b>) Luciferase activity of the −178/+92 E-cadherin promoter was measured in HCT116 and HCT116 E6 cells. n = 3 independent experiments. (<b>c</b>) Schematic representation of the luciferase plasmid under the control of the E-cadherin promoter. Negative regulatory elements Epal, E-box and positive elements CAAT, GC-I and GC-II are shown as is the mt Epal, with the two-nucleotide inactivating mutation. (<b>d</b>) Activity of wild type and mt Epal E-cadherin promoters in HCT116 and HCT116 E6 cells. Luciferase activity of co-transfected pRL-SV40 was used as a control for transfection efficiency and for normalization. n = 8 independent experiments. (<b>e</b>) RNA was extracted from HCT116 and HCT116 E6 cells that had been either untreated or treated with HDAC inhibitor, TSA, for 24 h. E-cadherin mRNA levels were measured by qRT-PCR and normalized to GAPDH mRNA levels. n = 3 independent experiments.