EGR-1, a UV-Inducible Gene in p53−/− Mouse Cells

Abstract

Changes in gene expression were examined in p53−/− and p53+/+ mouse cells after ultraviolet (UV) irradiation. Differential display was used to identify differentially expressed gene(s) in UV-treated p53−/− and p53+/+ cells. One of the differentially expressed genes was EGR-1 (early growth response gene-1), which was shown to be induced only in p53−/− cells. The induction of this gene by UV was detected as early as 0.5 h, peaked at 2 h, and returned to normal levels by 4 h. De novo protein synthesis was not required for UV-induced EGR-1 expression in p53−/− cells. Pretreatment of p53−/− cells with suramin, an inhibitor of growth factor receptors, completely suppressed UV-induced EGR-1 expression, suggesting that the induction may be mediated via the growth factor receptors. The presence of wild-type p53 suppressed the induction of EGR-1 after UV treatment. Overexpression of EGR-1 promoted the UV-induced transformation in p53+/+ cells, but not in p53−/− cells. These data suggested that EGR-1 may be an important player in the UV responses of mammalian cells and may influence UV-induced transformation.