Åke Borg
Principal investigator
An exon 5 deletion variant of the estrogen receptor frequently coexpressed with wild-type estrogen receptor in human breast cancer
Author
Summary, in English
Recent evidence suggests that the expression of estrogen receptor (ER) variants in breast cancer may interfere with wild-type (wt) ER function and be related to tumor progression and resistance to hormone treatment. One of these variants, ER delta E5, lacking that part of the hormone-binding domain encoded by exon 5, has previously been identified in breast tumors with the unusual estrogen receptor negative (ER-) and progesterone receptor positive (PgR+) phenotype and found to possess constitutive and hormone-independent transcriptional activity. Using a ribonuclease protection assay, we analyzed 27 breast tumors and 4 breast cell lines for the presence of this variant. We found the ER delta E5 variant to be expressed, not only in all of three ER-/PgR+ tumors but also in 19 of 20 ER+/PgR+ or ER+/PgR- tumors. Moreover, the variant was always coexpressed with and often in excess of wtER. ER delta E5 was also found in three breast cancer cell lines (MCF7, T47D, and ZR75-1), although to a lesser extent than wtER. A complete absence of both ER delta E5 and wtER was noted in four ER-/PgR- tumors and one normal breast cell line (HBL-100). Thus, our data suggest that the occurrence of ER delta E5 in breast cancer may represent a critical stage in tumor progression to autonomy.
Department/s
- Breastcancer-genetics
- Familial Breast Cancer
Publishing year
1993-12-15
Language
English
Pages
4-5882
Publication/Series
Cancer Research
Volume
53
Issue
24
Links
Document type
Journal article
Publisher
American Association for Cancer Research Inc.
Topic
- Cancer and Oncology
Keywords
- Breast Neoplasms/metabolism
- Exons
- Female
- Gene Deletion
- Humans
- Phenotype
- Receptors, Estrogen/analysis
- Receptors, Progesterone/analysis
- Tumor Cells, Cultured
Status
Published
Research group
- Familial Breast Cancer
ISBN/ISSN/Other
- ISSN: 0008-5472