Because of the great usefulness of estrogen receptor determinations in selecting therapy for breast cancer patients, a number of histochemical and immunohistochemical methods for visualizing bound estrogen in cells and tissue sections have been proposed. We discuss all of these histochemical methods in the light of the known properties of the estrogen receptor and other estrogen binders, and we consider some criteria that must be met if such

An antimicrobial substance which resembles a bacteriocin was identified in culture supernatant fluids of Lactobacillus helveticus strain CNRZ450. The bacteriocin was active against a narrow range of strains from closely related species of homofermentative lactobacilli. Its mode of action appeared to be bacteriostatic. Partial purification of the bacteriocin suggested that it was a complex protein with a mol. wt of between 30 and 50 kDa, although there is some evidence that the polypeptide monomer has a mol. wt of around 17 kDa. There was no evidence indicating an extrachromosomal location for its genetic determinant. PCR generated an amplicon from total DNA from strain CNRZ450 using primers based on the helJ gene sequence. A fragment showing homology to this amplicon was located in an EcoRI digest of total DNA from strain CNRZ450. The pattern obtained was different from that obtained with the helveticin J producer strain NCFB481. It is possible, therefore, that the antimicrobial from strain CNRZ450 is related to helveticin J at the DNA sequence level although the physical properties of the two antimicrobials reveal several differences.

Indirect immunofluorescence and immunoperoxidase assays were developed to detect estradiol and progesterone in breast cancer cells. Appropriate controls were used to confirm immunologic specificity. Studies of estradiol binding by human breast cancer cells identified three groups: no detectable binding (25%); all tumor cells exhibiting binding although to different degrees (4%); and tumors with varying numbers of positive and negative cells (71%). Similar observations were made with respect to progesterone binding. The percentage of cells with estradiol binding was correlated with the amount of estrogen receptors (ER) present in the tumor specimens. Post-hormone binding events e.g., nuclear binding of estradiol, were also evaluated. Some tumor cells showing cytoplasmic binding of estradiol did not show nuclear binding of estradiol; such tumors lacked detectable diethylstilbestrol under routine assay conditions, and relatively high concentrations of estradiol were needed to observe estradiol-specific staining. The results suggest that the immunocytochemical assays detect hormone-specific binding, but that the binding is probably due to multiple classes of steroid-binding sites.

No abstract