Search PubMed⌕ Search

Biomedical subjects

A Weisz

Publications and source records attributed to A Weisz.

63 records · Page 4Linked to original sources
PubMed1984

Interaction of sodium molybdate with highly purified glucocorticoid receptor.

Sodium molybdate can affect the properties of the glucocorticoid receptor in relatively crude preparations. To obtain more information as to whether these effects are due to direct interactions of the ion with the receptor or with other components present in the receptor-containing mixtures, the effects were examined of sodium molybdate on glucocorticoid receptors purified 3000-5000-fold to about 10% homogeneity from rat liver cytosol. The ion was found to: (1) increase the stability of the purified receptor at either 0 or 20 degrees C, although the effect was more pronounced at 20 degrees C (2) induce an apparent dimerization of the receptors as judged by sephadex G-150 gel filtration and sucrose density gradient sedimentation and (3) decrease the ionic strength required for elution of the purified receptor from DEAE-cellulose columns. Although, it is conceivable that each of these observed effects is due to indirect actions of the ion on contaminants in the preparations, it is more likely that the ion exerts its effects through direct interactions with the receptor.

Animals↗
PubMed1984

Estradiol and progesterone receptors in malignant gastrointestinal tumors.

Estradiol and progesterone receptors were assayed in tumors from 79 patients with primary colorectal and 56 patients with stomach adenocarcinomas. Eighteen of 79 colorectal cancers contained estradiol receptor, while 34 specimens were positive for progesterone receptor. In stomach cancer, the positive samples were 8 for estradiol and 14 for progesterone receptors. In both types of tumors, the Kd was in the range of 10(-10) M for estradiol and 10(-9) M for progesterone receptor, respectively. In colorectal adenocarcinomas, the presence of progesterone receptor seems to be partially correlated to the presence of estradiol receptor while, in stomach tumors, this correlation is lost. The positivity of at least one receptor in colorectal cancers is higher in the female sex. The contrary occurs for stomach cancer. Sucrose gradient centrifugation showed that cytoplasmic estradiol receptor of stomach cancer sedimented at 8S or 4 to 5S at low ionic strength. The isoelectric point of stomach cancer estradiol receptor is 6.5.

Adenocarcinoma↗
PubMed1983

Steroid derivatives for electrophilic affinity labelling of glucocorticoid binding sites: interaction with the glucocorticoid receptor and biological activity.

To investigate the possible use of electrophilic affinity labelling for the characterization of glucocorticoid receptors, different chemically reactive derivatives of deoxycorticosterone (deoxycorticosterone 21-mesylate and deoxycorticosterone 21-(1-imidazole) carboxylate), dexamethasone (dexamethasone 21-mesylate, dexamethasone 21-iodoacetate and dexamethasone 21-bromoacetate) and progesterone (21-chloro progesterone) were tested for their ability to bind irreversibly to the glucocorticoid receptor from goat lactating mammary gland. Using partially purified receptor, only one of the steroids tested, dexamethasone 21-mesylate (DXM-M) was found more effective than dexamethasone (DXM) in preventing exchange of radioactive dexamethasone in the receptor binding site. The affinity of DXM-M for the glucocorticoid receptor, measured by competitive binding assay, was 1/15 that of DXM. Polyacrylamide gel electrophoresis in sodium dodecyl sulphate of the [3H]-DXM-M labeled glucocorticoid receptor revealed a specific covalently radiolabeled fraction corresponding to an apparent molecular weight of 75,000 to 80,000. The biological activity of DXM-M was studied in RPMI 3460-clone 6 Syrian hamster melanoma cells, a cell line which is sensitive to growth inhibition by glucocorticoids. Like DXM, DXM-M inhibits the growth of RPMI 3460-clone 6 cells and it acts as a slowly reversible glucocorticoid agonist at concentrations which correlate with the affinity of DXM-M for the glucocorticoid receptor in vitro.

Affinity Labels↗
PubMed1981

Assay of total estradiol receptor in tissue homogenate and tissue fractions by exchange with sodium thiocyanate at low temperature.

After injection of radioactive estradiol to ovariectomized rats, the [3H]estradiol--receptor complex transferred to the nuclei can be solubilized by low concentrations of NaSCN. The extraction by NaSCN is significantly more efficient than that obtained by KCl and is, in fact, complete; i.e., no radioactivity can be found in the nuclei after extraction. Since NaSCN also induces the exchange of receptor-bound estradiol with free hormone [Sica, V., Puca, G. A., Molinari, A. M., Buonaguro, F. M., & Bresciani, F. (1980) Biochemistry 19, 83], a simple assay method has been set up which measures receptor in tissue and tissue fractions, including nuclei and whole homogenate, at 0--4 degrees C, irrespective of whether the receptor is or is not interacting with endogenous hormone. The procedure consists of a simple incubation step at 0--4 degrees C overnight (16 h) of the nuclear fraction, cytosol, and a total homogenate in the presence of excess radioactive estradiol and 0.5 M NaSCN. This method is very easy to carry out, accurate, and precise and avoids the loss of binding sites which results from the heating procedures utilized in other methods. The ability to measure the binding in both the soluble and the particulate fractions of rat uterus permits the determination of the rate of the cytoplasmic to nuclear transfer of estrogen after injection of various hormone concentrations. No nuclear transfer was observed after administration of other nonestrogen hormones such as progesterone, testosterone, or hydrocortisone while a nonsteroid antiestrogen, tamoxifen, was able to translocate the receptor. It was found that 2 h after injection of estradiol into ovariectomized rats total receptor content of uterus shows a decrease which is proportional to the amount of hormone injected. After injection of a hyperphysiological dose of 17 beta-estradiol, a certain amount of the receptor--hormone complex remains in the cytosol for at least 4 h. The nuclear turnover of estradiol receptor related to the progesterone receptor induction has been studied. Actinomycin D and cycloheximide prevent nuclear processing.

Animals↗
PubMedDate not supplied

Quantitative real-time RT-PCR analysis of eight novel estrogen-regulated genes in breast cancer.

BACKGROUND: Biological markers capable of predicting the risk of recurrence and the response to treatment in breast cancer are eagerly awaited. Estrogen and progesterone receptors (ER, PgR) in tumor cells mark cancers that are more likely to respond to endocrine treatment, but up to 40% of such patients do not respond. Here, the expression of a group of estrogen-regulated genes, previously identified by microarray analysis of in vitro models, was measured in breast tumors and possible associations with other clinicopathological variables were investigated. METHODS: The expression of CD24, CD44, HAT-1, BAK-1, G1P3, TIEG, NRP-1 and RXRalpha was measured by quantitative real-time RT-PCR on RNA from eighteen primary breast tumors. Statistical analyses were used to identify correlations among the eight genes and the available clinicopathological data. RESULTS: Variable expression levels of all the genes were observed in all the samples examined. Significant associations of CD24 with tumor size, CD44 with lymph node invasion, and HAT-1 and BAK-1 with ER positivity were found. The possible combinatorial value of these genes was assessed. Unsupervised hierarchical clustering analysis demonstrated that the expression profile of these genes was able to predict ER status with an acceptable approximation. CONCLUSIONS: Eight novel potential markers for breast cancer have been preliminarily characterized. As expected from in vitro data, their expression is able to discriminate ER- versus ER+ tumors.

Acetyltransferases↗