Impaired prostate tumorigenesis in Egr1-deficient mice

The transcription factor, early growth response protein 1 (ECR1), is overex pressed in a majority of human prostate cancers and is implicated in the re gulation of several genes important for prostate tumor progression. Here we have assessed the effect of Egr1 deficiency on tumor development in two tr ansgenic mouse models of prostate cancer (CR2-T-Ag and TRAMP). Using a comb ination of high-resolution magnetic resonance imaging and histopathological and survival analyses, we show that tumor progression was significantly im paired in Egr1(-/-) mice. Tumor initiation and tumor growth rate were not a ffected by the lack of Egr1; however, Egr1 deficiency significantly delayed the progression from prostatic intra-epithelial neoplasia to invasive carc inoma. These results indicate a unique role for Egr1 in regulating the tran sition from localized, carcinoma in situ to invasive carcinoma.