Decreased Egr-1 expression in human, mouse and rat mammary cells and tissues correlates with tumor formation

Int J Cancer. 1997 Jul 3;72(1):102-9. doi: 10.1002/(sici)1097-0215(19970703)72:1<102::aid-ijc15>;2-l.


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.

Publication types

  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • Animals
  • Blotting, Northern
  • Breast / metabolism
  • Breast Neoplasms / metabolism*
  • DNA-Binding Proteins / metabolism*
  • Early Growth Response Protein 1
  • Fluorescent Antibody Technique, Indirect
  • Humans
  • Immediate-Early Proteins*
  • Immunoblotting
  • Mammary Glands, Animal / metabolism
  • Mammary Neoplasms, Experimental / metabolism*
  • Mice
  • Rats
  • Tamoxifen / pharmacology
  • Transcription Factors / metabolism*
  • Tumor Cells, Cultured


  • DNA-Binding Proteins
  • EGR1 protein, human
  • Early Growth Response Protein 1
  • Egr1 protein, mouse
  • Egr1 protein, rat
  • Immediate-Early Proteins
  • Transcription Factors
  • Tamoxifen