Expression pattern of the AP-1 family in breast cancer: Association of fosB expression with a well-differentiated, receptor-positive tumor phenotype
✍ Scribed by Ana-Maria Bamberger; Carola Methner; Björn W. Lisboa; Carsten Städtler; Heinrich M. Schulte; Thomas Löning; Karin Milde-Langosch
- Publisher
- John Wiley and Sons
- Year
- 1999
- Tongue
- French
- Weight
- 261 KB
- Volume
- 84
- Category
- Article
- ISSN
- 0020-7136
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✦ Synopsis
In the present study, the expression of members of the AP-1 family of transcription factors in breast tumors (n ؍ 53) was investigated by Western blot with antibodies specific for each of the AP-1 family members (c-jun, junB, junD and c-fos, fosB, fra1 and fra2). The tumors were characterized with regard to grading, staging, histology, steroid-receptorexpression status and c-erbB2/neu expression. For comparison, normal breast-tissue samples, human breast-cancer cell lines (T47D and MDA-MB231) and the transformed human breast epithelial cell line HBL100 were also analyzed. For c-jun, junB, c-fos and fra2, a relatively uniform expression pattern without significant differences among tumors was observed. junD-protein amounts varied strongly in the tumor specimens. fosB-expression levels also varied strongly in the tumors, weak/absent expression being found in 47%, while 45% exhibited strong/very strong levels of expression. While none of the other AP-1 family members showed significant correlations with clinico-pathological tumor parameters or receptor status, expression of fosB was found to correlate significantly with positive steroid-hormone-receptor status (in the tumors and the cell lines) and a more differentiated tumor phenotype. Expression of 2 fra-1-specific bands of 33 and 36.5 kDa showed significant negative correlation with fosB expression, as well as with estrogen-receptor status and differentiation. We conclude that strong differences in the expression pattern of AP-1 family members are present in breast tumors, and that certain members of this family, such as fosB and fra-1, might be involved in the pathogenesis of these tumors.