Decreased Egr-1 expression in human, mouse and rat mammary cells and tissues correlates with tumor formation.
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.
Huang
R P
RP
Department of Molecular Medicine, Northwest Hospital, Seattle, WA 98125, USA.
Fan
Y
Y
de Belle
I
I
Niemeyer
C
C
Gottardis
M M
MM
Mercola
D
D
Adamson
E D
ED
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
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