Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UNIPROT:P04155 (pS2)
 1,234 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Differential signalling between the two oestrogen receptor (ER) isoforms in the presence of tamoxifen has been described. We hypothesise that differential recruitment of the steroid receptor co-activator, SRC-3 to ER-alpha and ER-beta may in part explain associations between ER isoforms and response to endocrine treatment. SRC-3 was localised within epithelial cells of breast tumour tissue and was co-localised with ER-alpha and ER-beta, (n=112). Expression of SRC-3 was found to be positively associated with ER-alpha (P=0.0021) and inversely with ER-beta (P<0.0001). Uniquely, this study utilises primary cell cultures derived from patient tumours, thus providing samples not readily available in most molecular model systems. These samples have enabled us to investigate the influence of growth factor pathways on steroid receptor-co-activator interactions. In HER2 (human epidermal growth factor receptor 2) positive primary tumour cell cultures 17beta-estradiol induced a decrease in SRC-3, whereas upregulated SRC-3 expression. Furthermore, treatment with tamoxifen-induced SRC-3 recruitment to the ER-oestrogen response element and enhanced interaction between SRC-3 and ER-alpha, but not ER-beta. Knockdown of SRC-3 results in a concomitant loss of expression of the oestrogen target gene pS2. Furthermore, silencing of SRC-3 resensitizes endocrine resistant, HER2 positive cells to the anti-proliferative effects of tamoxifen. The ability of ER-alpha, but not ER-beta to recruit SRC-3 in the presence of tamoxifen may in part explain the differential ER isoform associations with recurrence in human breast cancer.
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PMID:Tamoxifen-induced ER-alpha-SRC-3 interaction in HER2 positive human breast cancer; a possible mechanism for ER isoform specific recurrence. 1715 59

Tamoxifen resistance is common for estrogen receptor alpha (ERalpha) positive breast cancer. Second-line therapies include aromatase inhibitors or fulvestrant. We have shown previously that fulvestrant reversed 17beta-estradiol-induced tumor regression of tamoxifen-stimulated MCF-7 xenografts (MCF-7TAMLT) treated for >5 years with tamoxifen in athymic mice and paradoxically stimulated growth. We investigated mechanisms responsible for growth by fulvestrant in the presence of physiologic estradiol and therapeutic strategies in vivo. The results demonstrated that only estradiol increased expression of the estrogen-responsive genes, c-myc, igf-1, cathepsin D, and pS2 mRNAs, in MCF-7E2 and MCF-7TAMLT tumors. Tamoxifen or fulvestrant decreased the estradiol-induced increase of these mRNAs in both tumor models. However, tyrosine-phosphorylated HER2/ neu, HER3, phospho-extracellular-regulated kinase-1/2 (ERK-1/2), and phospho-glycogen synthetase kinase 3alpha (GSK3alpha) and beta proteins were increased in MCF-7TAMLT tumors treated with fulvestrant compared to estradiol, control, or tamoxifen. Phospho-HER2/neu interacted with HER3 protein in MCF-7TAMLT tumors. In order to determine whether the functional interaction of HER2/neu with HER3 is critical for growth of fulvestrant-stimulated MCF-7TAMLT tumors, pertuzumab (an antibody that blocks HER2/neu-HER3 interaction) was used in an in vivo xenograft growth assay. Only growth of fulvestrant-treated MCF-7TAMLT xenografts was decreased significantly by 37.2% in response to pertuzumab (P=0.004). Pertuzumab specifically decreased the interaction of HER2/neu protein with HER3 in fulvestrant-stimulated MCF-7TAMLT tumors. These results suggested growth of MCF-7TAMLT tumors by tamoxifen or fulvestrant is potentially independent of ERalpha transcriptional activity as evidenced by lack of induction of four estrogen-responsive genes. The results suggested that growth of MCF-7TAMLT tumors treated with fulvestrant in the presence of physiologic estradiol is in part mediated through enhanced signaling from the HER2/neu-HER3 pathway as pertuzumab partially inhibited growth and the interaction of HER2/neu with HER3 in vivo.
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PMID:Role for HER2/neu and HER3 in fulvestrant-resistant breast cancer. 1720 34

The objective of this work was to determine the interactive effects between soy bioactive components and tamoxifen (TAM) on prevention of estrogen-dependent breast cancer (BRCA). We initially investigated the effects of soy isoflavone genistein and TAM on the growth and cell cycle progression of estrogen-dependent MCF-7 human BRCA cells, and on the expression of ERalpha, pS2 and EGFR genes in vitro. Genistein or TAM alone inhibited the growth of MCF-7 cells in part via G(1) phase arrest, but their combinations showed suggestive antagonistic effects. We further evaluated the effects of bioactive soy components and TAM on the growth inhibition of MCF-7 tumors in a clinically relevant breast tumor model. TAM and bioactive soy components, genistein and soy phytochemical concentrate (SPC), delayed the growth of MCF-7 tumors. The combination of TAM with genistein or SPC, especially at the lower dose of TAM, had synergistic effects on delaying the growth of MCF-7 tumors. Biomarker determination suggests that the combination of TAM and soy components may synergistically delay the growth of MCF-7 tumors via their combined effects on induction of tumor cell apoptosis and inhibition of tumor cell proliferation. In addition, genistein and TAM combination synergistically delayed the growth of breast tumor via decreased estrogen level and activity, and down-regulation of EGFR expression. The results from our studies suggest that further investigations may be warranted to determine if the combination of TAM and bioactive soy components may be used for prevention and/or treatment of estrogen-dependent BRCA.
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PMID:Soy phytochemicals synergistically enhance the preventive effect of tamoxifen on the growth of estrogen-dependent human breast carcinoma in mice. 1723 21

4-Methoxyequilenin (4-MeOEN) is an O-methylated metabolite in equine estrogen metabolism. O-methylation of catechol estrogens is considered as a protective mechanism; however, comparison of the properties of 4-MeOEN with estradiol (E(2)) in human breast cancer cells showed that 4-MeOEN is a proliferative, estrogenic agent that may contribute to carcinogenesis. 4-MeOEN results from O-methylation of 4-hydroxyequilenin, a major catechol metabolite of the equine estrogens present in hormone replacement therapeutics, which causes DNA damage via quinone formation, raising the possibility of synergistic hormonal and chemical carcinogenesis. 4-MeOEN induced cell proliferation with nanomolar potency and induced estrogen response element (ERE)-mediated gene transcription of an ERE-luciferase reporter and the endogenous estrogen-responsive genes pS2 and TGF-alpha. These estrogenic actions were blocked by the antiestrogen ICI 182,780. In the standard radioligand estrogen receptor (ER) binding assay, 4-MeOEN showed very weak binding. To test for alternate ligand-ER-independent mechanisms, the possibility of aryl hydrocarbon receptor (AhR) binding and ER-AhR cross talk was examined using a xenobiotic response element-luciferase reporter and using AhR small interfering RNA silencing in the ERE-luciferase reporter assay. The results negated the possibility of AhR-mediated estrogenic activity. Comparison of gene transcription time course, ER degradation, and rapid activation of MAPK/ERK in MCF-7 cells demonstrated that the actions of 4-MeOEN mirrored those of E(2) with potency for classical and nonclassical estrogenic pathways bracketing that of E(2). Methylation of 4-OHEN may not represent a detoxification pathway because 4-MeOEN is a full, potent estrogen agonist.
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PMID:Activation of estrogen receptor-mediated gene transcription by the equine estrogen metabolite, 4-methoxyequilenin, in human breast cancer cells. 1758 65

Neoadjuvant chemotherapy trials have consistently reported lower response rates in hormone receptor-positive (HR+) breast cancer when compared with HR- cases. Preoperative endocrine therapy has therefore become a logical alternative and has gained considerable momentum from the finding that aromatase inhibitors (AIs) are more effective than tamoxifen for HR+ breast cancer in both the neoadjuvant and adjuvant settings. The most convincing neoadjuvant trial to demonstrate the superiority of an AI versus tamoxifen was the P024 study, a large multinational double-blind trial in postmenopausal women with HR+ breast cancer ineligible for breast-conserving surgery. The overall response rate (ORR) was 55% for letrozole and 36% for tamoxifen (P<0.001). Significantly more letrozole-treated patients underwent breast-conserving surgery (45 vs. 35%, respectively; P=0.022). In addition, ORR was significantly higher with letrozole than tamoxifen in the human epidermal growth factor receptor HER1/HER2+ subgroup (P=0.0004). The clinical efficacy of letrozole in HER2+ breast cancer was confirmed by fluorescent in situ hybridization analysis and was found to be comparable to that of HER2- cases (ORR 71% in both subsets). Biomarker studies confirmed the superiority of letrozole in centrally assessed estrogen receptor-positive (ER+) tumors and found a strong relationship with the degree of ER positivity for both agents. Interestingly, letrozole was effective even in marginally ER+ tumors and, unlike tamoxifen, consistently reduced the expression from estrogen-regulated genes (progesterone receptor and trefoil factor 1). Furthermore, when analyzed by Ki67 immunohistochemistry, letrozole was significantly more effective than tamoxifen in reducing tumor proliferation (P=0.0009). Thus, neoadjuvant letrozole is safe and superior to tamoxifen in the treatment of postmenopausal women with HR+ locally advanced breast cancer.
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PMID:Letrozole in the neoadjuvant setting: the P024 trial. 1791 34

ERBB2 overexpression in estrogen receptor (ER)-positive breast cancer cells such as BT474 (BT) cells has been found to confer resistance to tamoxifen, and suppression of ERBB2 improves the antiproliferative effects of tamoxifen. In this study, the responsiveness to tamoxifen in the BT/HerR, Herceptin-resistant BT cell lines established through constant Herceptin exposure, was evaluated. Compared with BT cells, improvement of sensitivity to tamoxifen in BT/HerR was demonstrated by ER functional analysis and cell proliferation assay. Tamoxifen in the resistant cell line was found to inhibit 17beta-estradiol-stimulating estrogen-responsive gene pS2 expression more effectively than in BT cells in real-time PCR assay. Western blot analysis showed that cross-phosphorylation between ER and downstream components of ERBB2 was attenuated in BT/HerR cells. ER redistribution from cytoplasm to nucleus could be found in these cells through immunofluorescence and confocal studies, and importantly, chromatin immunoprecipitation studies demonstrated that tamoxifen induced occupancy of the pS2 promoter by ER and nuclear receptor corepressor (NCOR1) instead of coactivator NCOA3 in these cells. Finally, combination of tamoxifen and Herceptin was found to improve the sensitivity of BT/HerR cells to Herceptin. Our results suggest that the ER genomic pathway in the ER-positive and Herceptin-resistant breast cancer cells may be reactivated, allowing tamoxifen therapy to be effective again, and a combination of tamoxifen and Herceptin can be a potential therapeutic strategy for ER-positive and Herceptin-resistant human breast cancer.
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PMID:Improvement of sensitivity to tamoxifen in estrogen receptor-positive and Herceptin-resistant breast cancer cells. 1876 63

Trefoil factor family (TFF) peptides provide protective and reparative effects by enhancing epithelial integrity and promoting mucosal restitution. TFF peptide expression is induced after mucosal damage. These processes are of central physiological relevance during the postnatal intestinal development and are strongly influenced during the weaning period. In piglets, weaning at early maturation stages frequently causes mucosal inflammation. The aim of this study was to evaluate postnatal intestinal TFF expression in a piglet probiotic trial. Low intestinal TFF2 expression was measured at early maturation stages. Weaning, however, was associated with a distinct response of increased TFF2 expression, indicating an important role in enhancing mucosal integrity. In the distal jejunum and ileum weaning could as well be associated with increased TFF3 mRNA levels. Differential TFF1 expression was not detected. Furthermore, TFF2 localization studies in different intestinal loci were performed by means of immunohistochemistry. Expression of selected genes (TGFA, EGFR, Cox-2) known to promote TFF signaling showed differential expression pattern as well, thereby providing further functional background. Furthermore, the expression patterns of EGFR observed in this study contribute to an advanced view of previous findings of EGFR regulation mainly obtained in rodents. An upregulated EGFR expression during early postnatal development suggests a local relevance to porcine intestinal maturation. However, a feed supplementation with the probiotic strain Enterococcus faecium did not influence TFF expression.
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PMID:Intestinal expression of TFF and related genes during postnatal development in a piglet probiotic trial. 1925 9

In many cases, the process of cancer cell differentiation is associated with the programmed cell death. In the present study, interestingly, we found that eupatilin, one of the pharmacologically active ingredients of Artemisia asiatica that has been reported to induce apoptosis in human gastric cancer AGS cells, also triggers differentiation of these cells. Treatment of AGS cells with eupatilin induced cell cycle arrest at the G(1) phase with the concomitant induction of p21(cip1), a cell cycle inhibitor. This led us to test whether eupatilin may trigger AGS cells to differentiate into the matured phenotypes of epithelial cells and this phenomenon may be coupled to the apoptosis. Eupatilin induced changes of AGS cells to a more flattened morphology with increased cell size, granularity, and mitochondrial mass. It also markedly induced trefoil factor 1 (TFF1), a gene responsible for the gastrointestinal cell differentiation. Eupatilin dramatically induced redistribution of tight junction proteins such as occludin and ZO-1, and F-actin at the junctional region between cells. It also induced phosphorylation of extracellular signal-regulated kinase 2 and p38 kinase. Blockade of ERK signaling by PD098059 or the dominant-negative ERK2 significantly reduced eupatilin-induced TFF1 and p21 expression as well as ZO-1 redistribution, indicating that ERK cascades may mediate eupatilin-induced AGS cell differentiation. Collectively, our results suggest that eupatilin acts as a novel anti-tumor agent by inducing differentiation of gastrointestinal cancer cells rather than its direct role in inducing apoptotic cell death.
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PMID:Eupatilin exhibits a novel anti-tumor activity through the induction of cell cycle arrest and differentiation of gastric carcinoma AGS cells. 1928 88

The aim of this study was to determine whether the extracellular-signal-regulated kinase 1/2 (ERK1/2) pathway is involved in genistein- and equol-induced cell proliferation and estrogen receptor (ER) alpha transactivation. For MCF-7 human breast cells, low concentrations of genistein and equol enhanced proliferation and induced MCF-7 cells to enter the S-phase. Genistein- and equol-induced cell proliferation and S-phase entry were blocked by the ERalpha antagonists 4-hydroxytamoxifen and ICI 182,780 and by the mitogen-activated protein kinase 1/2 inhibitor U0126. These data indicated that ERalpha and mitogen-activated protein extracellular kinase/ERK signaling were required for the effects of genistein/equol on cell growth and cell cycle progression. Genistein and equol induced delayed and prolonged activation of ERK1/2. Inhibition of ERK1/2 phosphorylation by U0126 led to complete suppression of genistein- and equol-induced estrogen response element reporter activity and to suppression of the estrogen-responsive gene pS2. The anti-estrogen ICI had no effect on genistein- and equol-induced ERK1/2 phosphorylation. These results suggest that activation of ERK1/2 lies upstream of ER-mediated transcription, and that ERK1/2 activation is necessary for the transactivation of ERalpha. In conclusion, genistein and equol elicit a delayed activation of ERK1/2, and this activation appears to be involved in the proliferation of breast cancer cells and estrogen-dependent transcriptional activation.
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PMID:Delayed activation of extracellular-signal-regulated kinase 1/2 is involved in genistein- and equol-induced cell proliferation and estrogen-receptor-alpha-mediated transcription in MCF-7 breast cancer cells. 1942 79

We report a prospective study of women over 70 years of age with early breast cancer who had primary endocrine treatment. Core biopsies of the cancer were taken at diagnosis and assessed using immunohistochemistry for oestrogen receptor (ER), progesterone receptor (PgR), epidermal growth factor receptor (EGFR), pS2, cyclin D1, p21, p53, HER2 and MIB1 (Ki67). Outcome analysis was performed at a median follow-up of 70 months. Correlation was sought between tumour marker measurements and disease control. When all patients were considered, a significant relationship was found between the absence of ER and PgR, the presence of p53 and EGFR, and high MIB1 and treatment failure. However, for the ER positive cancers, no other marker predicted treatment failure or relapse. There remains an important clinical need to identify those ER positive breast cancers that will not respond to endocrine treatment, and those in which the response will be short-lived.
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PMID:Tumour markers predictive of successful treatment of breast cancer with primary endocrine therapy in patients over 70 years old: a prospective study. 1996 69


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