title: Decreased Egr-1 expression in human, mouse and rat mammary cells and tissues correlates with tumor formation.
abstract: We have examined several types of tumor cell lines and shown that they invariably expressed little or no Egr-1, in contrast to their normal counterparts. We have previously shown that the expression of exogenous Egr-1 in human breast and other tumor cells markedly reduces transformed growth and tumorigenicity. We therefore hypothesized that the loss of Egr-1 expression plays a role in transformation. All human and mouse breast cancer cell lines and tumors examined had reduced Egr-1 expression compared with their normal counterparts. Reduced Egr-1 expression was also observed in 7,12-dimethylbenz(a)anthracene (DMBA)-induced rat mammary tumors, and this level increased to normal levels in tumors that regressed after tamoxifen treatment. We concluded, therefore, that loss of Egr-1 expression may play a role in the deregulation of normal growth in the tumorigenic process and that Egr-1 acts as a tumor suppressor gene.
authors.affiliation: Department of Molecular Medicine, Northwest Hospital, Seattle, WA 98125, USA.
authors.forename: R P
authors.initials: RP
authors.lastname: Huang
authors.forename: Y
authors.initials: Y
authors.lastname: Fan
authors.forename: I
authors.initials: I
authors.lastname: de Belle
authors.forename: C
authors.initials: C
authors.lastname: Niemeyer
authors.forename: M M
authors.initials: MM
authors.lastname: Gottardis
authors.forename: D
authors.initials: D
authors.lastname: Mercola
authors.forename: E D
authors.initials: ED
authors.lastname: Adamson
mesh_terms: D000818:Animals; D015152:Blotting, Northern; D001940:Breast / Q000378:metabolism; D001943:Breast Neoplasms / Q000378:metabolism*; D004268:DNA-Binding Proteins / Q000378:metabolism*; D051766:Early Growth Response Protein 1; D019084:Fluorescent Antibody Technique, Indirect; D006801:Humans; D017874:Immediate-Early Proteins; D015151:Immunoblotting; D008321:Mammary Glands, Animal / Q000378:metabolism; D008325:Mammary Neoplasms, Experimental / Q000378:metabolism*; D051379:Mice; D051381:Rats; D013629:Tamoxifen / Q000494:pharmacology; D014157:Transcription Factors / Q000378:metabolism*; D014407:Tumor Cells, Cultured
chemical_list: D004268:DNA-Binding Proteins; C497325:EGR1 protein, human; D051766:Early Growth Response Protein 1; C486109:Egr1 protein, mouse; C486110:Egr1 protein, rat; D017874:Immediate-Early Proteins; D014157:Transcription Factors; D013629:Tamoxifen