Expression pattern of the AP-1 family in breast cancer: association of fosB expression with a well-differentiated, receptor-positive tumor phenotype.
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-receptor-expression 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.
Bamberger
A M
AM
Institute of Pathology, University Hospital, Eppendorf, Hamburg, Germany.
Methner
C
C
Lisboa
B W
BW
Städtler
C
C
Schulte
H M
HM
Löning
T
T
Milde-Langosch
K
K
D001943:Breast Neoplasms / Q000737:chemistry* / Q000473:pathology; D018567:Breast Neoplasms, Male / Q000737:chemistry*; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D008970:Molecular Weight; D010641:Phenotype; D010766:Phosphorylation; D016760:Proto-Oncogene Proteins c-fos / Q000032:analysis*; D016755:Proto-Oncogene Proteins c-jun / Q000032:analysis*; D011960:Receptors, Estrogen / Q000032:analysis*; D011980:Receptors, Progesterone / Q000032:analysis*; D014407:Tumor Cells, Cultured
D016760:Proto-Oncogene Proteins c-fos; D016755:Proto-Oncogene Proteins c-jun; D011960:Receptors, Estrogen; D011980:Receptors, Progesterone