UNIPROT:P04155 - FACTA Search

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Query: UNIPROT:P04155 (pS2)
1,234 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Antiestrogens are efficient inhibitors of estrogen-mediated growth of human breast cancer. Besides inhibiting estradiol-stimulated growth, antiestrogens may have a direct growth-inhibitory effect on estrogen receptor (ER) positive cells and thus be more efficient than aromatase inhibitors, which will only abrogate estrogen-dependent tumor growth. To address this issue, we have used the human breast cancer cell line MCF-7/S9 as a model system which is maintained in a chemically defined medium without serum and estrogen. The addition of estradiol results in an increase in cell growth rate. Thus, the MCF-7/S9 cell line is estrogen-responsive but not estrogen-dependent. Three different types of antiestrogens, namely tamoxifen, ICI 182,780 and EM-652 were found to exert a significant and dose-dependent inhibition of basal growth of MCF-7/S9 cells. The growth-inhibitory effect of the three antiestrogens was prevented by simultaneous estradiol treatment. Antiestrogen treatment also reduced the basal pS2 mRNA expression level, thus indicating spontaneous estrogenic activity in the cells. However, treatment with the aromatase inhibitor had no effect on basal cell growth, excluding that endogenous estrogen synthesis is involved in basal growth. These data demonstrate that in addition to their estrogen antagonistic effect, antiestrogens have a direct growth-inhibitory effect which is ER-mediated. Consequently, in the subset of ER positive breast cancer patients with estrogen-independent tumor growth, antiestrogen therapy may be superior to treatment with aromatase inhibitors which only inhibit estrogen formation but do not affect cancer cell growth in the absence of estrogens.
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PMID:Effect of antiestrogens and aromatase inhibitor on basal growth of the human breast cancer cell line MCF-7 in serum-free medium. 1273 92

Expression of cyclooxygenase-2 (Cox-2) is elevated in gastric adenocarcinomas and precursor lesions leading to this disease. Mice deficient for trefoil factor 1 (TFF1) develop a pyloric adenoma with full penetrance. Because inhibition of Cox-2 suppresses tumor growth in several animal models, we studied expression of Cox-2 and effect of a selective Cox-2 inhibitor celecoxib in gastrointestinal tissues of the TFF1-deficient mice. Cox-2 mRNA and protein were strongly expressed in the pyloric adenomas of the TFF1(-/-) mice as detected by in situ hybridization and immunohistochemistry. Nonneoplastic gastrointestinal tissues of wild-type or TFF1(-/-) mice expressed low or nondetectable levels of Cox-2. Celecoxib (1600 ppm p.o. for 3 months) caused ulceration and inflammation of the adenoma in all treated TFF1(-/-) mice (n = 7). This effect of the drug was adenoma specific, because no histological alterations were observed in the non-neoplastic gastric or intestinal tissues in the TFF1(-/-) or wild-type mice receiving the drug treatment. All untreated TFF1(-/-) mice had an adenoma (n = 7), but none demonstrated the combination of ulceration and inflammation. Our data show that Cox-2 is expressed in gastric adenomas of the TFF1(-/-) mice and suggest that inhibition of Cox-2 disturbs the integrity of the adenoma by promoting ulceration and inflammation. These findings support the effort to initiate clinical studies to investigate the effect of Cox-2 inhibitors as a chemotherapeutic modality for dysplasias of the stomach.
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PMID:Cyclooxygenase-2 expression and effect of celecoxib in gastric adenomas of trefoil factor 1-deficient mice. 1281 Jun 22

Arzoxifene (ARZ) is a selective estrogen receptor (ER) modulator with greater bioavailability than raloxifene which is being developed as treatment for breast cancer. We have used an in vivo model of hormone-sensitive breast cancer to study the growth-inhibitory and pharmacodynamic effects of ARZ in comparison with the most widely used antiestrogen, tamoxifen (TAM). We compared the abilities of ARZ and TAM to antagonize the estrogen (E2)-dependent growth of MCF-7 human breast cancer xenografts in oophorectomized athymic mice. At four different time points over 28 days, we studied their time-related pharmacodynamic effects on biomarkers of tumor growth (cell proliferation/death measured by Ki-67 and apoptosis scores), cell cycle activity (cyclin D1 and p27(kip1)), and hormone-regulated gene expression (ERalpha, progesterone receptor, and pS2). Although maximal growth inhibition was seen after E2 withdrawal, ARZ and TAM induced significant and similar inhibition of E2-stimulated tumor growth. Inhibition of growth was reflected by changes in the tumor growth index (ratio posttreatment/pretreatment Ki-67/apoptosis scores). ARZ and TAM resulted in a significant (P < 0.001) increase in ER expression and reduction in progesterone receptor expression, whereas changes in cyclin D1 score were inversely related to p27(kip1) score. A significant but delayed biological effect was observed with a 10-fold lower dose of ARZ. These results show that ARZ is an effective antagonist of E2-stimulated breast cancer growth with similar growth-inhibitory and pharmacodynamic effects to TAM in this model.
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PMID:Comparison of the selective estrogen receptor modulator arzoxifene (LY353381) with tamoxifen on tumor growth and biomarker expression in an MCF-7 human breast cancer xenograft model. 1455 45

We hypothesized that the phytosterols beta-sitosterol (BSS), beta-sitosterol glucoside (BSSG), and Moducare (MC; BSS:BSSG = 99:1) could modulate the growth of estrogen-dependent human breast cancer cells in vitro and in vivo. The present study evaluated the estrogenic and antiestrogenic effects of BSS, BSSG, and MC (0.001 to 150 micromol/L) on the proliferation of Michigan Cancer Foundation 7 (MCF-7) cells in vitro. Both BSS (>1 micromol/L) and MC (>50 micromol/L) increased MCF-7 cell proliferation. Treatment with 150 micro mol/L of BSS and MC increased cell growth by 2.4 and 1.5 times, respectively, compared to the negative control (NC) group. However, BSSG had no effect at the concentrations tested. The effects of dietary BSS, BSSG, and MC on the growth of MCF-7 cells implanted in ovariectomized athymic mice were also evaluated. Estrogenic effects of the phytosterols were evaluated in the NC, BSS, BSSG, and MC treatment groups, and antiestrogenic effects were evaluated in the 17 beta-estradiol (E(2)), E(2) + BSS, E(2) + BSSG, and E(2) + MC treatment groups. Mice were treated with dietary BSS (9.8 g/kg AIN93G diet), BSSG (0.2 g/kg diet), or MC (10.0 g/kg diet) for 11 wk. Dietary BSS, BSSG, and MC did not stimulate MCF-7 tumor growth. However, dietary BSS, BSSG, and MC reduced E(2)-induced MCF-7 tumor growth by 38.9% (P < 0.05), 31.6% (P = 0.08), and 42.13% (P < 0.05), respectively. The dietary phytosterols lowered serum E(2) levels by 35.1, 30.2, and 36.5% in the E(2) + BSS, E(2) + BSSG, and E(2) + MC groups, respectively (P < 0.05), compared to that of the E(2) treatment group. Estrogen-responsive pS2 mRNA expression in tumors did not differ among groups, but expression of the antiapoptotic marker B-cell lymphoma/leukemia-2 (bcl-2) in tumors from the E(2) + MC group was downregulated, compared to that of the E(2) treatment group. In summary, BSS and MC stimulated MCF-7 cell growth in vitro. Although BSSG comprises only 1% of MC, BSSG made MC less estrogenic than BSS alone in vitro. However, dietary BSS and MC protected against E(2)-stimulated MCF-7 tumor growth and lowered circulating E(2) levels.
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PMID:beta-Sitosterol, beta-Sitosterol Glucoside, and a Mixture of beta-Sitosterol and beta-Sitosterol Glucoside Modulate the Growth of Estrogen-Responsive Breast Cancer Cells In Vitro and in Ovariectomized Athymic Mice. 1511 61

Soy-based products consumed in Asian countries are minimally processed whereas in the USA many of the soy foods and soy ingredients are highly processed. Soy foods contain complex mixtures of bioactive compounds, which may interact with one another. The objective of this study was to evaluate the ability of various soy products containing genistin, the glycoside form of genistein, to affect growth of MCF-7 cells transplanted into ovariectomized athymic mice. Products investigated included soy flour, two crude extracts of soy (soy molasses and Novasoy(R)), a mixture of isoflavones and genistin in pure form. Each of the soy flour-processed products was added to the diet to provide equivalent amounts of genistein aglycone equivalents (750 p.p.m.). Tumors in the negative control animals regressed throughout the study while the tumors in the soy flour-fed animals remained basically the same size (neither grew nor regressed). In animals consuming soy molasses, Novasoy(R), mixed isoflavones or genistin alone, tumor growth was stimulated when compared with animals consuming a control diet devoid of soy. These same dietary treatments resulted in increased cellular proliferation. Changes in mRNA expression of gene targets (estrogen responsiveness, cell cycle progression, apoptosis and aromatase activity) in tumors induced by the different diets were evaluated. The relative expression of pS2, progesterone receptor and cyclin D1 was increased in animals consuming the Novasoy(R), mixed isoflavones and genistin. Bcl2 mRNA expression was low in most of the dietary treatment groups compared with positive (estradiol implant) controls. Aromatase expression was not affected in any of the treatment groups. The degree of soy flour processing affects the estrogenicity of products containing a constant amount of genistein. Collectively, these findings suggest that for postmenopausal women with estrogen-dependent breast cancer, the consumption of foods containing soy flour is more advisable than consuming isoflavones in more purified forms.
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PMID:Soy processing influences growth of estrogen-dependent breast cancer tumors. 1513 Oct 10

Approximately 60% of all breast tumors are estrogen-responsive and chemicals that show estrogenic or anti-estrogenic properties are able to interact with breast tumor growth. In a breast tumor, adipose stromal cells (fibroblasts) surrounding the epithelial tumor contain the aromatase enzyme, which converts androgens into estrogens. Exposure to aromatase inducers can therefore lead to increased estrogen levels and possibly to accelerated breast tumor growth. Subsequently, breast tumor cells synthesize and secrete elevated levels of factors such as prostaglandin E2 (PGE2), interleukin-6 (IL-6), and IL-6 soluble receptor (IL-6sR), which in turn have the ability to stimulate aromatase gene transcription in fibroblasts, establishing a positive feedback loop. In this study, a technique that allows for culturing MCF-7 epithelial breast tumor cells and healthy primary human mammary fibroblasts together in one compartment was developed. To establish the positive feedback loop, the co-culture was exposed to estrogenic compounds. RNA was isolated and reverse-transcriptase polymerase chain reaction (RT-PCR) was performed on the aromatase and pS2 genes. Exposure of the co-culture to estradiol (E2), diethylstilbestrol (DES), and bisphenol-A (BPA), resulted in a three- to seven-fold increase of pS2 transcription levels. Furthermore, pS2 transcription levels increased even more when the aromatase substrate testosterone (20 nM) was present in the co-culture medium. Exposure of the co-culture to the aromatase inducer dexamethasone (DEX) resulted in increased pS2 transcription levels, as well as increased aromatase transcription levels. Simultaneous exposure to DEX and the synthetic anti-estrogen ICI 182,780 almost completely blocked the pS2 response. The aromatase induction response was not altered by ICI 182,780 treatment. Simultaneous exposure to DEX and the non-steroidal aromatase inhibitor fadrozole, abolished the effect of the presence of testosterone in the co-culture medium, but did not result in pS2 gene transcription levels as low as seen after exposure to ICI 182,780. These observations indicate the presence of a positive feedback loop in our co-culture system. This co-culture provides a more sophisticated and sensitive system to detect direct and indirect estrogenic effects of compounds and their possible effects on breast tumor promotion.
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PMID:Co-culture of primary human mammary fibroblasts and MCF-7 cells as an in vitro breast cancer model. 1552 92

Genistein and daidzein are the main isoflavones in legumes. Equol is an intestinal bacterial metabolite of daidzein. In this study, we evaluated the estrogenic potential of daidzein and synthetic (+/-)-equol to stimulate growth of estrogen-dependent breast cancer (MCF-7) in vitro and in vivo. We hypothesize that estrogenic effects of daidzein and (+/-)-equol could modulate the growth of MCF-7 cells both in vitro and also once implanted into ovariectomized athymic mice. At concentrations between 0.001 and 50 microM, daidzein and (+/-)-equol stimulated the growth of MCF-7 cells with maximal stimulation at 1 muM in vitro. To evaluate their effects on the growth of MCF-7 cells implanted in ovariectomized athymic mice, two dietary dose-response studies [daidzein (125, 250, 500 and 1000 p.p.m.) and (+/-)-equol (250, 500 and 1000 p.p.m.)] were conducted. Tumor size and body weight were monitored weekly during the study. At completion of the study, we analyzed cellular proliferation of tumors using immunohistochemical staining (ki-67), pS2 expression in tumors using a real time quantitative reverse transcription-polymerase chain reaction (qRT-PCR), and total daidzein and (+/-)-equol levels in plasma using liquid chromatography-electrospray tandem mass spectrometry (LC-ES/MS/MS). Dietary daidzein had a slight but significant stimulatory effect on MCF-7 tumor growth in mice. No significant induction of pS2 mRNA (an estrogen-responsive marker) in tumors by dietary daidzein was observed. Total plasma daidzein concentrations in plasma were between 0.25 and 1.52 microM. Dietary equol treatment (for 37 weeks) did not stimulate MCF-7 tumor growth. There were no statistical differences in tumor size, proliferation and pS2 expression among any treatment groups. Total equol concentrations in plasma were 2.10-3.21 microM. In conclusion, daidzein and (+/-)-equol have proliferative effects on MCF-7 cell growth in vitro within the concentration range tested. Dietary daidzein had a slight but significant stimulatory effect on tumor growth, whereas (+/-)-equol did not stimulate the growth of estrogen-dependent breast tumor growth in athymic mice, increase the cell proliferation in tumors, or induce an estrogen-responsive pS2 expression. Total daidzein or (+/-)-equol plasma levels in mice fed the isoflavones were in the range that stimulated MCF-7 cell growth in vitro. These results suggest that pharmacokinetic and/or metabolic factors attenuate the estrogenic effects of daidzein and equol in vivo.
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PMID:Effects of dietary daidzein and its metabolite, equol, at physiological concentrations on the growth of estrogen-dependent human breast cancer (MCF-7) tumors implanted in ovariectomized athymic mice. 1639 73

The present study was designed to investigate the effects of a phytoestrogens-containing soy extract (SOYSELECT, SSE) on the growth of estrogen-dependent (MCF-7) and estrogen-unresponsive (MDA-MB-231) human breast cancer xenografts in athymic mice. Results obtained provided evidence that MCF-7 tumors did not grow over the treatment period (5 weeks) in ovariectomized females receiving 50 or 100 mg/kg/day SSE (oral route); administration of SSE also did not affect the estradiol-sustained growth of MCF-7 tumors in mice. Similarly, no effects on tumor growth were observed in SSE-treated mice bearing MDA-MB-231 xenografts. Data from pS2, progesterone receptor and cyclin D1 mRNA expression in tumors showed that, although SSE was able to induce a moderate estrogenic effect in MCF-7 cells, it did not increase cellular proliferation and tumor growth, in our experimental conditions. Besides, when used in association with 17beta-estradiol, it displayed antiestrogenic activity. The expression of other genes involved in tumor progression and angiogenesis, such as Thrombospondin 1, Transforming Growth Factor beta2 and Kallikrein 6 was also evaluated in tumor samples, results showing a decrease in mRNA expression upon SSE treatment. The effect of SSE on angiogenesis in vivo was also evaluated in the Matrigel plug assay; results obtained showed a striking anti-angiogenic activity in mice receiving 100 mg/kg/day SSE, thereby confirming that this extract may interfere with angiogenesis. Collectively, these experimental data suggest that SSE could be not harmful for women with a history of or at high risk for breast cancer, at least for short treatment periods; however, further studies are needed to thoroughly characterize the activity profile of the extract in this specific setting of patients.
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PMID:Lack of stimulatory activity of a phytoestrogen-containing soy extract on the growth of breast cancer tumors in mice. 1640 Jan 87

The cochaperone p23 plays an important role in estrogen receptor alpha (ER) signal transduction. In this study, we investigated how p23 regulates ER target gene activation and affects tumor growth and progression. Remarkably, we found that changes in the expression of p23 differentially affected the activation of ER target genes in a manner dependent upon the type of DNA regulatory element. p23 overexpression enhanced the expression of the ER target genes cathepsin D and pS2, which are regulated by direct DNA binding of ER to estrogen response elements (ERE). In contrast, the expression of other target genes, including c-Myc, cyclin D1, and E2F1, to which ER is recruited indirectly through its interaction with other transcription factors remains unaffected by changes in p23 levels. The p23-induced expression of pS2 is associated with enhanced recruitment of ER to the ERE in the promoter, whereas ER recruitment to the ERE-less c-Myc promoter does not respond to p23. Intriguingly, p23-overexpressing MCF-7 cells exhibit increased adhesion and invasion in the presence of fibronectin. Our findings demonstrate that p23 differentially regulates ER target genes and is involved in the control of distinct cellular processes in breast tumor development, thus revealing novel functions of this cochaperone.
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PMID:The cochaperone p23 differentially regulates estrogen receptor target genes and promotes tumor cell adhesion and invasion. 1680 59

Although crosstalk between cell-surface and nuclear receptor signaling pathways has been implicated in the development and progression of endocrine-regulated cancers, evidence of direct coupling of these signaling pathways has remained elusive. Here we show that estrogen promotes an association between extranuclear estrogen receptor alpha (ER) and the epidermal growth factor receptor (EGFR) family member ERBB4. Ectopically expressed as well as endogenous ERBB4 interacts with and potentiates ER transactivation, indicating that the ERBB4/ER interaction is functional. Estrogen induces nuclear translocation of the proteolytic processed ERBB4 intracellular domain (4ICD) and nuclear translocation of 4ICD requires functional ligand-bound ER. The nuclear ER/4ICD complex is selectively recruited to estrogen-inducible gene promoters such as progesterone receptor (PgR) and stromal cell-derived factor 1 (SDF-1) but not to trefoil factor 1 precursor (pS2). Consistent with 4ICD-selective promoter binding, suppression of ERBB4 expression by interfering RNA shows that 4ICD coactivates ER transcription at the PgR and SDF-1 but not the pS2 promoter. Significantly, ERBB4 itself is an estrogen-inducible gene and the ERBB4 promoter harbors a consensus estrogen response element (ERE) half-site with overlapping activator protein-1 elements that bind ER and 4ICD in response to estrogen. Using a cell proliferation assay and a small interfering RNA approach, we show that ERBB4 expression is required for the growth-promoting action of estrogen in the T47D breast cancer cell line. Our results indicate that ERBB4 is a unique coregulator of ER, directly coupling extranuclear and nuclear estrogen actions in breast cancer. We propose that the contribution of an autocrine ERBB4/ER signaling pathway to tumor growth and therapeutic response should be considered when managing patients with ER-positive breast cancer.
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PMID:Coregulation of estrogen receptor by ERBB4/HER4 establishes a growth-promoting autocrine signal in breast tumor cells. 1691 74

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