[Transcription factor NF-kappa B/RelA are constitutively activated and localized in the cell nuclei of E1A + cHa-Ras...

DNA binding activity and intracellular distribution of transcription factor NF-kappa B in primary embryo fibroblast (REF) cells transformed by the complementing oncogenes E1A plus cHa-ras have been studied. By means of a gel retardation assay with a regulatory element kappa B, we showed that DNA binding activity of NF-kappa B increased upon transformation. In contrast to normal REF cells, the elevated activity of NF-kappa B in the transformants cannot be regulated by growth factors of serum and phorbol ester. Moreover, an immunofluorescence study showed that the main component of NF-kappa B factor--p65/Re1 protein--was constitutively localized in the nucleus of E1A + cHa-ras transformants independently on the growth conditions: serum starvation or serum stimulation. Mechanisms of constitutive activation of transcription factor NF-kappa B upon transformation of REF cells by E1A + cHa-ras oncogenes have been discussed.