The recently discovered pS2 protein is expressed under estrogen control in a subset of estrogen receptor-positive breast cancers and in an estrogen-independent manner in normal stomach mucosa.
Simulation of this pedigree assuming independent inheritance of breast cancer and estrogen-receptor genotypes led to a lod score greater than or equal to 1.85 only once in 2,000 replicates.
We examined the DNA binding of ER in MCF-7 cells and 79 primary breast cancers by gel mobility shift assay using as a probe the estrogen response element (ERE).
This also has implications for the therapy of breast cancer because it may be necessary to design effective anticancer agents to suppress the malignant effects of ER mutants.
Furthermore, it has been suggested that EGF-R levels are higher in estrogen receptor negative (ER-) than in ER+ human breast tumors and that EGF-R status may be a prognostic indicator in breast cancer.
In estrogen receptor positive and negative breast cancer cell lines, the mRNA coding for pro-cathepsin D is overexpressed and sorting and maturation of the pro-enzyme are altered, leading to accumulation of the active proteinase in large endosomes and to secretion of the precursor (52K protein).
The T-47D human breast cancer cell line was treated with the synthetic progestin, ORG 2058, and the resultant changes in ER mRNA and ER levels determined by Northern analysis and radioligand binding, respectively.
Thus the ER appears to be normal in two independently isolated breast cancer cell lines whose growth is resistant to the inhibitory effect of antiestrogens.
T47DCO cells, genetically unstable and containing estrogen receptor mutations, are a model for the progression of breast cancers to hormone resistance.
The induction of both pNR-1 and pNR-2 requires similar physiological concentrations of estradiol and is near maximal at 10(-10) M. An increase in the levels of the RNAs is seen after 30 min of estrogen treatment, but pNR-1 reaches its maximal concentration faster than pNR-2. pNR-1 and pNR-2 were not expressed in all human breast cancer cell lines tested. pNR-1 was expressed and regulated by estrogen in the estrogen receptor-positive cell lines, MCF-7, T-47D, and ZR 75, whereas pNR-2 was not expressed in the T-47D cell line. pNR-1 and pNR-2 were not detected in two estrogen receptor-negative cell lines (BT20 and HBL 100).
We have examined the effects of reversibly and irreversibly binding estrogenic and antiestrogenic ligands for the estrogen receptor on pS2 RNA accumulation in MCF-7 human breast cancer cells and on pS2-chloramphenicol acetyl transferase (CAT) fusion gene expression in transfected MCF-7 cells.
The abundance of TGF beta and TGF alpha mRNA in human breast cancer cell lines was not related directly to proliferation rate of the cells in culture or estrogen receptor positivity or negativity.
Initial studies in human breast cancer cell lines suggested a possible association between the absence of one allele and the absence of ER expression; subsequent analysis of allele distribution and frequency in 188 primary human breast tumor biopsies did indeed show a significant but not complete correlation between the absence of one allele and the failure to express ER.
Increased expression of the glutathione S-transferase (GST; E.C.2.5.1.18) pi class isozyme is associated with both malignant transformation and drug resistance, as well as with decreased estrogen receptor content in breast cancer.
These data support the view that ER and EGR-R gene expression is inversely regulated in human breast cancer and describe for the first time an inhibitory effect of a phorbol ester on steroid hormone receptor gene expression.
A new approach allowing an early prognosis in breast cancer: the ratio of estrogen receptor (ER) ligand binding activity to the ER-specific mRNA level.
Regulation of estrogen receptor messenger ribonucleic acid and protein levels in human breast cancer cell lines by sex steroid hormones, their antagonists, and growth factors.