Analysis of the epidermal growth factor receptor promoter: the effect of nuclear factor-kappaB.

The epidermal growth factor receptor gene is highly regulated and responsive to extracellular stimuli that control cell growth. We have identified five putative nuclear factor-kappaB (NF-kappaB) binding sites within the epidermal growth factor receptor (EGFR) promoter region by sequence analysis. We have analyzed the potential role of NF-kappaB family members in the regulation of the EGFR transcription. Electrophoretic mobility shift analysis demonstrated that the p50 and p49, subunit proteins of the NF-kappaB, bound to the EGFR promoter at four out of five of these sites. However, it was found that NF-kappaB could not transactivate the EGFR by cotransfection experiments with each NF-kappaB subunit, using p50, p65 and c-Rel and an EGFR promoter luciferase reporter. Treatment of cells with tumor necrosis factor (TNF)-alpha, which could degrade the I-kappaB and then result in translocation of NF-kappaB to nucleus, did not enhance EGFR promoter reporter gene transcription. Also, TNF-alpha did not induce EGFR expression at the protein level. These results indicate that even though purified NF-kappaB can bind to the putative sites, there is no evidence that NF-kappaB transactivates the EGFR promoter region.