Early growth response gene 1 (EGR1) is deleted in estrogen receptor-negative human breast carcinoma.
BACKGROUND
Patients with estrogen receptor (ER)-positive and ER-negative breast carcinomas differ in terms of disease progression, treatment regimens, and prognosis. The mechanism underlying the biologic differences of the two groups is understood poorly. Array comparative genome hybridization (CGH) on breast carcinoma subtypes demonstrated a consistent association between loss in regions of chromosome 5q and ER-negative tumors. It was shown previously that early growth response gene 1 (EGR1) on 5q acts like a tumor-suppressor gene, with its expression repressed in breast carcinomas.


METHODS
To test the hypothesis that EGR1 is deleted differentially in ER-negative versus ER-positive breast carcinomas, fluorescence in situ hybridization was employed in this study to determine the EGR1 deletion status in 50 breast carcinoma specimens. Deletion status was measured by the signal ratio of EGR1/chromosome 5. Linear regression was used to assess the results.


RESULTS
The mean EGR1/chromosome 5 ratio for the ER-negative group was significantly lower compared with the same ratio for the ER-positive group (P < 0.001). Although grade alone was not significant for predicting the ratio, the interaction between ER status and grade was significant (P < 0.01): For ER-negative specimens, the higher the grade, the lower the EGR1/chromosome 5 ratio.


CONCLUSIONS
The EGR1 gene appeared to be deleted in ER-negative human breast carcinomas. Egr-1 may contribute to the pathogenesis of ER-negative breast carcinomas versus ER-positive breast carcinomas.
Division of Human Genetics, Department of Genetics and Developmental Biology, University of Connecticut Health Center, Farmington, Connecticut 06030-6140, USA.
Karyn
K
Ronski
Melinda
M
Sanders
Joseph A
JA
Burleson
Victor
V
Moyo
Peter
P
Benn
Min
M
Fang
D001943:Breast Neoplasms / Q000737:chemistry / Q000235:genetics*; D004268:DNA-Binding Proteins / Q000235:genetics*; D051766:Early Growth Response Protein 1; D005260:Female; D017353:Gene Deletion; D018734:Genes, erbB-2; D006801:Humans; D017874:Immediate-Early Proteins / Q000235:genetics*; D019656:Loss of Heterozygosity; D011960:Receptors, Estrogen / Q000032:analysis*; D014157:Transcription Factors / Q000235:genetics*
D004268:DNA-Binding Proteins; C497325:EGR1 protein, human; D051766:Early Growth Response Protein 1; D017874:Immediate-Early Proteins; D011960:Receptors, Estrogen; D014157:Transcription Factors