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)

Antagonists of steroid hormones are clinically important in the management of breast cancer. However, the duration of response is limited due to the development of hormone-independent tumors in virtually all cases. In an attempt to obtain insight into the mechanisms underlying antiestrogen resistance, the consequences of epigenetic changes in gene expression were studied in vitro. Estrogen-dependent ZR-75-1 human breast cancer cells were treated with 5-azacytidine, an inhibitor of DNA methylation, and cultured in the absence of estradiol or in the presence of antiestrogens. Estrogen-independent cell colonies developed within 3 weeks at high frequency in 5-azacytidine-treated cultures (0.7 x 10(-3), in contrast to control cultures (< or = 10(-8). The derived cells (ZR/AZA) were resistant to 4-hydroxytamoxifen and ICI 164,384, independent of the selection protocol, but had lost the ability to grow anchorage-independent. Whereas expression of estrogen receptor, progesterone receptor, and pS2 were down-regulated, expression of epidermal growth factor (EGF) receptor and HER2/neu were increased in ZR/AZA cells. In contrast to the stable altered expression patterns of estrogen receptor and EGF receptor, transient keratin 7 expression was observed. Transforming growth factor-alpha mRNA was identified in ZR-75-1 cells and ZR/AZA cells and EGF-like peptides were secreted in the culture medium. Proliferation of ZR/AZA cells could be partially inhibited with an EGF receptor-blocking antibody. Presence of both growth factor receptors and possible ligands suggests the development of an autocrine growth mechanism. Our data show that epigenetic alterations of gene expression result in rapid progression of breast cancer cells to hormone independence.
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PMID:Induction of estrogen independence of ZR-75-1 human breast cancer cells by epigenetic alterations. 753 60

For quantificative determination of ERBB2 gene amplification in archival human carcinoma specimens we have developed a rapid, non-radioactive approach, which is based on the differential polymerase chain reaction (PCR) and fluorescent DNA technique. Sequences from the ERBB2 gene and from a single-copy reference gene were amplified simultaneously by PCR, in which one of each primer pair was fluorescently labelled. PCR products were separated by polyacrylamide gel electrophoresis in an automated DNA sequencer and directly quantified after laser activation and emission scanning using appropriate software. This fluorescent differential polymerase chain reaction (fd-PCR) method was used for quantificative determination of ERBB2 gene amplification in 195 formalin-fixed, paraffin-embedded breast carcinoma tissues. ERBB2 gene amplification was found in 52 (26%) of these tumors and correlated significantly with tumor size, absence of estrogen receptor (ER) and pS2 expression, but not with absence of progesterone receptor (PR) or presence of epidermal growth factor receptor (EGF-R) expression, lymph-node metastases or grading. In univariate analysis, ERBB2 gene amplification showed no significant correlation with clinical outcome, either in the whole population or in the subgroup defined by positive axillary lymph-node metastases. However, within the node-negative subgroup, patients with ERBB2 gene amplification had significantly decreased relapse-free survival and overall survival (p < 0.05). The fd-PCR assay is a valuable tool for determination of amplification of ERBB2 gene as well as further oncogenes. In this way, more detailed information about individual tumor biology may be acquired by a routine assay.
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PMID:ERBB2 gene amplification detected by fluorescent differential polymerase chain reaction in paraffin-embedded breast carcinoma tissues. 759 Dec 99

Changes in estrogen receptor (ER) expression and function may explain the development of tamoxifen resistance in breast cancer. ER expression was measured by an immunohistochemical assay, validated for use in tamoxifen-treated tumors against a biochemical enzyme immunoassay, in 72 paired biopsies taken before treatment and at progression or relapse on tamoxifen. Progesterone receptor (PgR) and pS2 gene expression were also measured immunohistochemically as an indicator of ER function. Overall the frequency of ER expression was reduced from 37 of 72 (51%) pretamoxifen to 21 of 72 (29%) at progression or relapse, with a significant reduction in the quantitative level of ER (P < 0.0001; Wilcoxon signed rank sum test). Tumors treated with primary tamoxifen that responded but then developed acquired resistance frequently remained ER positive (ER+) at relapse: 16 of 18 (89%) were ER+ pretamoxifen (75% of these expressed either PgR or pS2) and 11 of 18 (61%) were ER+ at relapse (82% continued to express PgR or pS2). In contrast, only 3 of 20 (15%) tumors that progressed on primary tamoxifen with de novo resistance were ER+ pretamoxifen, and all tumors were ER- at progression. At progression, 6 of 20 (30%) of these tumors expressed high levels of PgR (mean H-score, 98) and/or pS2 (mean, 50% cells positive), despite being ER-. In tumors that recurred during adjuvant tamoxifen therapy, including locoregional and metastatic lesions, ER expression was significantly reduced from 18 of 34 (53%) in the original primary tumor to 10 of 34 (29%) at relapse (P = 0.002). PgR expression was likewise significantly reduced in this group (P = 0.001). This study confirms that expression of a functional ER in breast cancer is a strong predictor for primary response to tamoxifen. Although ER was reduced in tamoxifen-resistant tumors overall, the development of acquired resistance was associated with maintained ER expression and function in many tumors, whereas de novo resistance remained related to lack of ER expression. Recurrence during adjuvant tamoxifen was associated with development of an ER/PgR-negative phenotype in some tumors. These data imply that separate mechanisms of resistance may occur in these different clinical subgroups.
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PMID:Changes in estrogen receptor, progesterone receptor, and pS2 expression in tamoxifen-resistant human breast cancer. 761 68

We have investigated the ability of several transcriptionally inactive estrogen receptor (ER) mutants to block endogenous ER-mediated transcription in MCF-7 human breast cancer cells. In transient transfections of MCF-7 cells, two of the mutants, a frame-shifted ER (S554fs) and a point-mutated ER (L540Q), strongly inhibit the ability of endogenous wild-type ER to activate transcription of estrogen-regulated reporter plasmids. A third mutant, ER1-530, which is missing 65 residues from its carboxy-terminus, is a weaker repressor of estradiol-stimulated transcription. When an estrogen response element (ERE)-thymidine kinase-chloramphenicol acetyltransferase reporter gene is used, S554fs, L540Q, and ER1-530 suppress the transcriptional activity of endogenous MCF-7 ER by 87%, 97%, and 62%, respectively. The magnitude of dominant negative repression is promoter specific; when an ERE-pS2-chloramphenicol acetyltransferase reporter is employed, inhibition of endogenous ER activity by equivalent amounts of S554fs, L540Q, and ER1-530 ranges from 85-97%. Dose-response studies show the S554fs mutant to be the most potent of the three ER mutants as a repressor of estrogen action in these cells. In addition, elevated levels of intracellular cAMP, achieved by the addition of 3-isobutyl-1-methylxanthine plus cholera toxin to cells, fail to compromise the effectiveness of these mutants as dominant negative ERs despite the cAMP-enhanced transcriptional activity of ER. The mutants are also powerful repressors of the agonist activity of trans-hydroxytamoxifen-stimulated ER transcription. The dominant negative activity of the three mutants is lost when the A/B domain of these receptors is deleted, implying an important role for this N-terminal region of the ER in the ability of these mutants to inhibit endogenous wild-type ER activity. All in all, the data suggest that S554fs in particular is a reasonable candidate for studies designed to use a dominant negative ER to inhibit the estrogen- and tamoxifen-stimulated growth of human breast cancer cells.
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PMID:Repression of endogenous estrogen receptor activity in MCF-7 human breast cancer cells by dominant negative estrogen receptors. 762 51

The growth-inhibitory actions of the pineal hormone, melatonin, on human breast tumor cells and the possible association between this inhibition and melatonin's down-regulation of the estrogen receptor (ER) expression were examined in the ER-positive, estrogen-responsive MCF-7 human breast tumor cell line. As previously reported, melatonin dramatically inhibits the growth of these breast tumor cells and down-regulates ER levels in these cells, suggesting that the modulation of ER may be an important mechanism by which melatonin inhibits breast cancer cell growth. In the present studies, Northern blot analysis was used to examine the expression of estrogen-regulated transcripts known to be involved in estrogen's mitogenic actions. Melatonin, at a physiologic concentration (10(-9) M), rapidly, significantly, and, in some cases, transiently elevated the steady-state mRNA levels of growth stimulatory products such as TGF alpha, c-myc, and pS2, which are normally up-regulated in response to estrogen. Conversely, melatonin decreased the expression of other factors normally up-regulated by estrogen, such as progesterone receptor and c-fos. Significant stimulation of the expression of the growth-inhibitory factor TGF beta was seen with melatonin treatment, potentially supporting the concept that melatonin's growth-inhibitory activity is mediated through the breast tumor cells' estrogen-response pathway. The early regulation of many of these products by melatonin suggests that mechanisms more rapid than the down-regulation of ER are important in melatonin's modulation of their expression. However, the long-term modulation of these transcripts (12-48 hr) may be heavily influenced by melatonin's down-regulation of ER expression. These results clearly define the need for additional in depth studies to dissect the cellular events leading to melatonin-induced growth inhibition in breast tumor cells.
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PMID:Melatonin modulation of estrogen-regulated proteins, growth factors, and proto-oncogenes in human breast cancer. 762 97

The authors immunohistochemically studied the expression of the estrogen receptor (ER), 27-kD heat shock protein (HSP27) and pS2 in 118 invasive primary human breast cancers. Positive nuclear staining of the ER was detected in 64% of the cases and was closely correlated with the biochemical assay (p < 0.0001). ER-positive tumors were significantly decreased with tumor size and stage (p < 0.001 each), but not with lymph node status. Positivity of the ER was correlated with the cytoplasmic expression of HSP27 (p < 0.005), pS2 (not significant) and HSP70 (not significant). ER negativity was significantly correlated with the expression of p53, epidermal growth factor receptor (EGFR) and c-erbB-2 (p < 0.05 each). Thus, it was concluded that ER-positive breast carcinomas, relatively small in size, preferentially expressed HSP27, HSP70 and pS2 and that ER-negative tumors, relatively large in size, were predisposed to express p53, EGFR and c-erbB-2.
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PMID:Immunohistochemical detection of estrogen receptor in invasive human breast cancer: correlation with heat shock proteins, pS2 and oncogene products. 763 53

pS2 protein assay was performed with Elsa-pS2 kit (CIS-Biointernational) on a group of 1,065 patients with operable breast cancer who underwent breast surgery in the years 1982 through 1990. The median follow-up was 57 months. This group included exclusively infiltrating ductal carcinoma with primary surgery. Age mean was 58 yr; T0-T1, 33.6%; T2-T4, 66.4%; Differentiation grade I, 29%; node negative, 53%; estrogen receptor (ER) positive, 62.4%; progesterone receptor (PR) positive, 55.2%; mean tumor size, 2.4 cm; local recurrence, 5.2%; metastasis, 17.5%. pS2 values varied from 0.1 to 707 ng/mg of cytosol protein (median, 5.6; mean 24.5; 95th percentile 112 ng/mg p). There was no significant relationship between the mean level of pS2 and age, tumor size, nodal status, whereas pS2 was related to histological grade (P < 10(-3)), ER (P < 10(-5)), and PR (P < 10(-5)). By using 2 ng/mg p as pS2 cutoff, 77/391 (19.7%) of ER+PR+ tumors were pS2-, and 122/345 (35.4%) of ER-PR-tumors were pS2+; with this cutoff, a strong relationship existed between pS2 and overall survival, but not between pS2 and relapse-free survival. With Cox multivariate analysis, pS2 protein was classified after lymph node status, histological size, ER, differentiation grade, age, clinical stage, PR. In patients with axillary lymph node involvement (N+), pS2 status could discriminate between good and bad prognosis, specially for patients with small tumors (< 2 cm) and with less than seven invaded nodes. This study showed that pS2 protein was a poor prognostic factor in comparison with classical factors.
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PMID:[PS2 as a prognostic factor in 1065 cases of human breast cancer. A multicenter study]. 770 45

Thyroid hormone (T3) and estradiol (Est) modulate biological processes by binding to nuclear receptor proteins that, through interactions with specific response elements in the regulatory regions of genes, modulate gene transcription. Est stimulation of estrogen receptor (ER)-positive breast carcinoma cell growth occurs through its ability to bind to the ER and activate gene transcription. We now report that physiological concentrations of T3 significantly enhance Est stimulation of growth of a number of human breast carcinoma cell lines. The effect of T3 is specific for Est stimulation of growth and has no effect on insulin-like growth factor-I stimulation of growth. The effect of T3 on enhancing Est-mediated growth was specifically blocked by the addition of ligands inducing retinoid X receptor (RXR) homodimer receptor formation, suggesting that RXR-thyroid nuclear receptor (TR) heterodimer formation is required for the T3-mediated effect on estradiol-stimulated growth. Four thyroid nuclear receptors have been described in tissues, TR alpha 1, alpha 2, beta 1, and beta 2. Breast carcinoma cells were found to express TR beta 1 and TR alpha 2 mRNA and very low levels of TR alpha 1 mRNA. T3 did not increase ER mRNA or protein levels and did not enhance Est-mediated increases in gene transcription of a number of genes, i.e., transforming growth factor-alpha and pS2 which contain estrogen-response elements (EREs) in their regulatory regions. However, T3 enhanced Est-stimulated ERE-TK-CAT activity. Thus significant cross-talk appears to occur between the TRs and ER and T3 appears to enhance Est-mediated gene transcription.
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PMID:Thyroid hormone enhancement of estradiol stimulation of breast carcinoma proliferation. 773 50

The effect of structure of the estrogen ligand on the accumulation of tPA mRNA and the activity of extracellular fibrinolytic enzyme has been examined in cultures of MCF-7 cells. Estradiol(E2)-stimulated fibrinolytic activity was preceded by an increase in actinomycin D sensitive tPA mRNA synthesis which peaked at 18 h. Ten A- and D-ring structural analogs of E2 affected tPA mRNA accumulation and extracellular fibrinolytic activity. Only in the case of two A-ring isomers (2- and 4-hydroxyestratrien-17 beta-ol) was the decreased effect of the ligand's structural change on tPA mRNA accumulation and fibrinolysis not explained by a comparable decline in affinity of the ligand for estrogen receptor. Both of these analogs functioned as antiestrogens. The stimulatory capacity of androstanediols on the tPA gene required that the 3-hydroxyl group be positioned in the beta-configuration. Absence of the 17 beta-hydroxy group was beneficial to the maximum accumulation of tPA mRNA. As has been reported for other estrogen responsive genes (progesterone receptor, cathepsin D and pS2), regulation by estrogens is not related directly to the affinity of the ligand for ER, but this activity may be determined by the location of the electronegative isopotential above the A-ring of estrogenic ligands.
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PMID:Induction of tissue plasminogen activator mRNA and activity by structurally altered estrogens. 774 7

The exon 5 deletion splice variant of estrogen receptor (delta 5 ER), which in vitro is constitutively active in the absence of estrogens, may have a role in conferring both tamoxifen resistance and ER-related phenotype in breast cancer. We have investigated the expression of this variant in vivo (at the level of mRNA) in relation to known tamoxifen resistance and expression of the estrogen-regulated genes progesterone receptor (PgR) and pS2. The amount of delta 5 ER mRNA relative to wild type (WT) ER mRNA (% delta 5/WT) was assayed in 70 tamoxifen-resistant and 50 primary breast carcinomas using reverse transcription/PCR. Both WT and delta 5 ER mRNA were detected in the majority of tumors, although delta 5 ER was detected only in the presence of WT ER. Overall no significant difference was seen in % delta 5/WT ER between tamoxifen-resistant and primary control tumors (medians, 13 and 15%, respectively). Tumors in both control and resistant groups which expressed PgR/pS2 in the absence of measurable ER protein (ER- PgR+ and ER- pS2+) had significantly higher delta 5 ER mRNA levels compared with other phenotypes (P < 0.002). This association with ER-/pS2+ tumors has not been demonstrated previously. In ER+ tumors which expressed pS2, significantly greater delta 5 ER mRNA expression was observed in tamoxifen-resistant compared with control tumors (P = 0.05). A similar although nonsignificant trend was observed in ER+ PgR+ tumors. While delta 5 ER mRNA is unlikely to be responsible for tamoxifen resistance in most breast cancers, elevated delta 5 ER mRNA levels may be important in some tumors, especially those which continue to express high levels of PgR/pS2.
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PMID:Exon 5 deletion variant estrogen receptor messenger RNA expression in relation to tamoxifen resistance and progesterone receptor/pS2 status in human breast cancer. 781 59


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