Transcriptional Activation of the Human Epidermal Growth Factor Receptor Promoter by Human p53

Abstract

The human epidermal growth factor receptor (EGFR) promoter is activated by both wild-type and tumorderived mutant p53. In this communication, we demonstrate that EGFR promoter sequence requirements for transactivation by wild-type and mutant p53 are different. Transient-expression assays with EGFR promoter deletions identified a wild-type human p53 response element, 5-AGCTAGACGTCCGGGCAGCCCCCGGCG -3, from positions ؊265 to ؊239. Electrophoretic mobility shift analysis and DNase I footprinting assays indicated that wild-type p53 binds sequence specifically to the response element. Using circularly permuted DNA fragments containing the p53-binding site, we show that wild-type p53 binding induces DNA bending at this site. We further show that the EGFR promoter is also activated by tumor-derived p53 mutants p53-143A, p53-175H, p53-248W, p53-273H, and p53-281G. However, the transactivation by mutant p53 does not require the wild-type p53-binding site. The minimal EGFR promoter from positions ؊104 to ؊20 which does not contain the wild-type p53-binding site is transactivated by the p53 mutants but not by the wild-type protein, showing a difference in the mechanism of transactivation by wild-type and mutant p53. Transactivation of the EGFR promoter by p53 may represent a novel mechanism of cell growth regulation.

DNA-conformation is an important determinant of sequence-specific DNA binding by tumor suppressor p53

“…This suggested that, in addition to the conformational status of the p53 protein, the nature of the binding site itself might be another important parameter for determining the sequence-speci®c interactions of p53 with DNA. In agreement with the view that the p53 binding site itself, in addition to conforming to the consensus, provides features which determine its binding by p53, is the ®nding that some sequences are e ciently bound by full length p53 without prior activation of the protein Foord et al, 1993;Wu et al, 1993;Ludes-Meyers et al, 1996), while others strictly require activation of p53 for being bound (Hupp et al, 1992;Miyashita and Reed, 1995;Zhao et al, 1996). Furthermore, data obtained with synthetic oligonucleotides suggested that there is a hierarchy among p53 binding sequences, as not all sequences that perfectly match the consensus are bound by p53 with the same or even similar efficiency .…”

Mutant p53 gain of function: differential effects of different p53 mutants on resistance of cultured cells to chemotherapy

“…Mutant p53 can upregulate the expression of a variety of genes (e.g. Chin et al, 1992;Deb et al, 1992;Dittmer et al, 1993;Tsutsumi-Ishi et al, 1995;Ludes-Meyers et al, 1996). Very recently, the c-myc oncogene was shown to be a potent target of many mutant p53 proteins, possibly accounting for some of their tumorigenic e ects (Frazier et al, 1998).…”

`Gain of function' phenotype of tumor-derived mutant p53 requires the oligomerization/nonsequence-specific nucleic acid-binding domain

“…Earlier we have shown that C-terminal deletion of p53-281G up to amino acid 327 causes a signi®cant decrease in transactivation of the human EGFR promoter (Ludes-Meyers et al, 1996) suggesting that the C-terminal oligomerization/nonsequence-speci®c nucleic acid-binding domain is necessary for mutant p53-mediated transactivation. Therefore, we tested whether the requirement for the C-terminal amino acids holds true for some other promoters that have also been shown to be transactivated by mutant p53; for that purpose we used the PCNA and MDR-1 promoters Chin et al, 1992;Dittmer et al, 1993).…”