Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UMLS:C0027651 (tumor)
 685,946 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Quantitative analyses of cytosolic steroid hormone receptors were performed on nine tumors from the transplantable rat prostatic adenocarcinoma R-3327H. Androgen receptors and estrogen receptors were found in eight of nine and five of six tumors, respectively. None of the tumours analyzed contained detectable progestin or glucocorticoid receptors (four and seven tumors, respectively). The apparent equilibrium dissociation constants for the androgen and estrogen receptors were 0.7-4.3 nM and 0.6-1.8 nM, respectively. The apparent equilibrium Bmax values (maximum number of binding sites) were 1,500-25,000 fmoles/gm tissue for the androgen receptor and 640 to 5,800 fmoles/gm tissue for the estrogen receptor. A comparison between the receptor contents of the R-3327H rat tumor and human benign prostatic hyperplasia and metastatic carcinoma of the prostate showed that the rat tumor was different from the human tissues in several respects. Hence, the search for an optimal animal model for prostatic carcinoma in man must be continued.
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PMID:Comparison of the R-3327H rat prostatic adenocarcinoma to human benign prostatic hyperplasia and metastatic carcinoma of the prostate with regard to steroid hormone receptors. 616 71

Plasminogen activator and nonspecific proteolytic activity in transplantable squamous cell rat prostate tumor 11095 were measured by a fluorometric method. Prostate tumors which regressed after treatment with D-Trp-6-LH-RH had 10-fold lower concentrations of plasminogen activator(s) per mg of protein, and considerably higher levels of nuclear androgen receptor. On the other hand, there were no significant changes in nonspecific proteolytic activity in tumor tissue between untreated and D-Trp-6-LH-RH treated rats. The prostate tumor had at least three different plasminogen activator-like bands, as determined by polyacrylamide gel electrophoresis with plasminogen as substrate. The decreased activity of plasminogen activator(s) and considerably higher levels of nuclear androgen receptors correlate with the regression of prostate tumors induced by the treatment of rats with D-Trp-6-LH-RH.
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PMID:Plasminogen activator and nuclear androgen receptor in rat prostate tumors after treatment with D-Trp-6-LH-RH. 624 Sep 95

A study was made of basic mechanisms involved in regression of breast cancer exposed to high levels of synthetic progestins. The possibility that progestins act on breast cancer by way of the progesterone receptor mechanism and subsequent increase of estradiol 17 beta-dehydrogenase activity could not be confirmed in this investigation. It is demonstrated that the progestins megestrol acetate and medroxyprogesterone acetate are strong competitors for steroids which bind specifically to androgen, glucocorticoid, and progesterone receptors, indicating that the progestins are able to bind to these receptors with high affinity. In contrast, these progestins do not compete with estradiol for estrogen receptor binding. In 34 patients with progressive metastatic breast cancer, results of receptor studies have been correlated with clinical response during treatment with megestrol acetate. Statistically, regressions were significantly associated with tumors containing large amounts of androgen receptors. Clinical correlation with the quantities of glucocorticoid receptor was weak, while such correlations with estrogen and progesterone receptors were absent. However, we did demonstrate relationships between the quantities of the various receptors in breast cancer. Tumors containing a large amount of androgen receptors also generally contain estrogen receptors. It might be that a favorable response to progestins is confined to the group of patients with hormone-responsive breast cancers, as such characterized by the presence of estrogen receptors, and that within this group the actual androgen receptor levels determine response.
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PMID:Estrogen, androgen, glucocorticoid, and progesterone receptors in progestin-induced regression of human breast cancer. 624 8

Juvenile nasopharyngeal angiofibromas (JNA) are rare. They have been frequently treated with estrogens, either solely or as an adjuvant therapy prior to surgery or irradiation. Clinical trials have proveded no evidence to explain the objective respose to estrogens observed in some tumors. Since the mechanism of steroid hormone action is mediated via specific receptors, we analyzed 8 JNA for tumor cytosol estrogen receptors. None were positive for estrogen receptors. Additionally, all were also negative for progesterone receptors. Nasopharyngeal angiofibromas occur predominantly in adolescent boys at a time when there is a gradual change in androgen availability. Therefore, three latter angiofibromas were also analyzed for the presence of cytosol androgen receptor. Specific testosterone and dihydrotestosterone binding components in the tumor cytosol were detected. This observation raises for the first time the possibility that JNA may be an androgen-dependent tumor. Estrogen may act as an antiandrogen on these tumors, an action similar to that on prostate cancer.
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PMID:Hormonal receptor determination in juvenile nasopharyngeal angiofibromas. 624 85

Sucrose density gradient analysis of cytosol from normal and neoplastic rat prostatic tissues exhibited a peak of (3H) retinoic acid binding in the 2S region, corresponding to the cytoplasmic retinoic acid binding protein (cRABP). In the Fisher-Copenhagen F1 rat, cRABP was present in the lateral lobe, but could not be detected in the ventral nor in the dorsal prostatic lobes. Four sublines of the R-3327 rat prostatic tumor contained similar levels of this binding protein. The absence of cRABP in the normal tissue of origin of the R-3327 tumor, the rat dorsal prostate, and reappearance in the neoplastic tissues follows a pattern described in other human and animal tumors. The occurrence of cRABP in the well-differentiated as well as in the anaplastic R-3327 tumors in which markers which reflect a state of differentiation and hormonal regulation, such as androgen receptor, 5 alpha reductase, and secretory acid phosphatase are either markedly reduced or absent, points to cRABP as a marker of malignant transformation.
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PMID:Retinoic acid binding protein in normal and neopolastic rat prostate. 628 3

The estrogen receptor was assayed in 8 intracranial meningiomas, 14 lung cancers, 3 thymomas and 2 malignant lymphomas using the dextran-charcoal method. Progesterone and androgen receptors were also assayed in all the cases of lung cancer. The estrogen receptor assay was positive in 3 meningiomas, 2 lung cancers, and all thymomas and malignant lymphomas. The androgen receptor assay was positive in one case of lung cancer but the progesterone receptor was negative in all assayed cases. No cases showed multiple receptor positivity. An antiestrogen (tamoxifen) was administered to one case each of intracranial meningioma and lung cancer with positive estrogen receptor. The receptor content was decreased to an undetectable level in the former after 4 months of administration. This finding suggests the estrogen dependency of the tumor. The lung cancer patient, however, died 2 weeks later without any evidence of hormone dependency.
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PMID:Sex steroid receptors in diverse human tumors. 629 Mar 6

The purpose of this study was to partially characterize the steroid binding activity of murine renal tumor cells in continuous culture. The steroid receptor content of a cloned renal tumor cell line (RAG) and a subline RAG-2 was examined by sucrose gradient analysis, hydroxylapatite and dextran-coated charcoal methods. The RAG cells lacked estrogen- and progestin-binding activity, whereas specific 5 alpha-dihydrotestosterone (DHT) and dexamethasone (Dx) binding activities were detected as 8S peaks on low salt gradients. The specificity of DHT binding was examined by sucrose gradient analysis: DHT, R1881 and ORG2058 all completely inhibited [3H]DHT binding whereas diethylstilbestrol and Dx were ineffective. The androgen receptor content of the RAG cells was approx. 15 fmol/mg cytosol protein by the hydroxylapatite-filter assay, with an estimated Kd for methyltrienolone (R1881) of 5 nM at 0 degrees C. Scatchard analysis of [3H]Dx binding by RAG cytosol showed a Kd of 6 nM for Dx and 44 nM for corticosterone at 0 degrees C. Glucocorticoid receptor levels were estimated to be 182 fmol/mg cytosol protein by dextran-coated charcoal assay. Metabolism of [3H]testosterone and [3H]DHT by RAG cells was examined 1, 4 and 6 h after exposure to labeled hormone. Radioactive DHT was the primary intracellular metabolite recovered after exposure to [3H]testosterone. There was little conversion of DHT to androstanediol.
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PMID:Steroid metabolism and binding activity in a murine renal tumor cell line. 633 89

The ductus deferens smooth muscle tumor cell line (DDT1MF-2) expresses c-sis protooncogene mRNA transcripts which encode at least one subunit of the potent mitogenic agent, platelet derived growth factor (PDGF). These cells also synthesize and secrete a protein which is immunologically identical to this growth factor. Therefore, PDGF is implicated in the autocrine regulation of DDT1MF-2 cell proliferation. While androgens also stimulate proliferation and induce an augmentation in androgen receptor levels in DDT1MF-2 cells, glucocorticoids inhibit both events and arrest cells in the G1 phase of the cell cycle. Addition of PDGF overcomes the glucocorticoid cell cycle arrest, but does not diminish the suppressive action on androgen receptor concentration. These findings are consistent with a mechanism by which glucocorticoids regulate DDT1MF-2 cell proliferation through modulation of PDGF expression which is independent of the glucocorticoid effects on androgen receptor concentrations.
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PMID:Autocrine regulation of growth: I. Glucocorticoid inhibition is overcome by exogenous platelet derived growth factor. 637 6

Several reports have shown that sodium molybdate stabilizes steroid hormone receptors. We have utilized these observations to develop an exchange assay for the androgen receptor at elevated temperatures. Exchange was found to be complete after 30 min at 30 degrees C. Receptor degradation was negligible during this treatment. Scatchard analysis indicated that the dissociation constant of the androgen receptor was similar both in the absence (Kd = 3.9 nM) and presence (Kd = 2.9 nM) of molybdate. Steroid specificity of the androgen receptor was unaltered by this treatment. The exchange procedure was reproducible, with an interassay variation of 2.45% and intraassay variation less than 10.0%. Using this assay, highest concentrations of androgen binding were measured in androgen target tissues of the rat (Dunning R3327 tumor, prostate and seminal vesicle; 23.37, 20.20 and 19.84 fmol/mg protein respectively). Lower concentrations were observed in other tissues (lung, brain, heart, spleen, liver and kidney; 9.06, 5.63, 3.50, 2.42, 2.33 and 1.36 fmol/mg protein respectively). These results demonstrate that molybdate stabilization of the androgen receptor allows efficient steroid exchange without significant alteration of the receptor's steroid binding properties. Furthermore, this exchange assay can be used to obtain a reasonable measurement of receptor concentrations in different androgen target tissues.
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PMID:Exchange assay for androgen receptors in the presence of molybdate. 638 80

The partially purified 4.5S [3H]dihydrotestosterone receptor binds to nuclear matrix isolated from rat Dunning prostate tumor with properties similar to those reported for androgen receptor binding in intact nuclei [Colvard, D.S., & Wilson, E.M. (1984) Biochemistry (preceding paper in this issue)] in that it requires Zn2+ and mercaptoethanol, is saturable, and is temperature dependent and of high affinity (Ka approximately 10(13) M-1). On a milligrams of DNA equivalent basis, the extent of matrix binding of androgen receptor (700 fmol of receptor bound/mg of matrix protein) is similar to that of intact nuclei, corresponding to approximately 1400 sites/nucleus. Association rate constants (ka) for 4.5S androgen receptor binding to matrix at 0, 15, and 25 degrees C are 2.7 X 10(5), 1.2 X 10(6), and 2.4 X 10(6) M-1 min-1, respectively, indicating an energy of activation of 15 kcal/mol. Up to 50% of matrix-bound receptor is extractable in buffer containing 3 mM ethylenediaminetetraacetic acid plus either 0.4 M KCl or 5 mM pyridoxal 5'-phosphate. A protein fraction designated 8S androgen receptor promoting factor that promotes conversion of the 4.5S androgen receptor to 8 S [Colvard, D. S., & Wilson, E. M. (1981) Endocrinology (Baltimore) 109, 496-504] has been further purified and found to inhibit the binding of the 4.5S androgen receptor to isolated nuclei and nuclear matrix in a concentration-dependent manner. The results support the hypothesis that the 8S steroid receptor is a complex of the activated 4.5S androgen receptor with a non-steroid binding protein that renders the receptor incapable of binding in nuclei.
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PMID:Androgen receptor binding to nuclear matrix in vitro and its inhibition by 8S androgen receptor promoting factor. 646 49


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