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)

The catecholestrogens, namely 2-hydroxyestradiol (2-OH-E2) and 4-hydroxyestradiol (4-OH-E2) are important, naturally occurring metabolites of E2. Here we studied their role on estrogen dependent processes. Using the MCF-7 cell line as a model system we analyzed the potency of 2- and 4-OH-E2 on the synthesis of the 160 kDa secreted protein and on the transcription of the pS2 mRNA. Both processes are known to be E2 inducible and are mediated by the estrogen receptor. Control incubations using E2 and antiestrogens were performed to validate the assay procedure and to enable us to comparatively study the effects of the catecholestrogens. Stimulating MCF-7 cells for 2 days with 10(-8) M 2- or 4-OH-E2 resulted in an induction of the synthesis of the 160 kDa protein and in an increase in pS2 mRNA. Following hormonal stimulation with 2- or 4-OH-E2 [35S]methionine labeling of MCF-7 cells increased the level of newly synthesized and secreted 160 kDa protein 54 and 88% compared with the inductive potency of E2 (100%). The pS2 mRNA in MCF-7 cells was increased by a 2 day treatment with 10(-8) M 2- or 4-OH-E2 by 48 and 79%, respectively, compared to E2. Therefore, we conclude that the estrogen receptor is transcriptionally active in MCF-7 cells upon binding of catecholestrogens. The estrogen receptor in vivo may be active if the intracellular concentration of catecholestrogens generated is sufficient to allow occupation of the receptor. The possible action of these hormones in vivo is discussed.
J Steroid Biochem Mol Biol 1994 Apr
PMID:Catecholestrogens are agonists of estrogen receptor dependent gene expression in MCF-7 cells. 818 Jan 6

We have examined the ability of estrogen receptor (ER) to bind and bend DNA fragments containing the Xenopus laevis vitellogenin A2 estrogen response element (ERE), which contains a palindromic, consensus ERE sequence, the X. laevis vitellogenin B1 ERE2, which contains a 1-bp mismatch in the 5'-end of the half-palindrome, and the human pS2 ERE, which contains a 1-bp mismatch in the 3'-end of the half-palindrome. ER binding induced a 65 degrees bend in DNA fragments containing the consensus ERE, the vitellogenin B1 ERE2, or the pS2 ERE. However, ER affinity for the consensus ERE was 2-fold greater than for either the vitellogenin B1 ERE2 or the pS2 ERE. When Chinese hamster ovary (CHO) cells were transfected with reporter plasmids containing either the consensus ERE, the vitellogenin B1 ERE2, or the pS2 ERE separated from the TATA sequence by 26 helical turns, exposure to 10 nm 17 beta-estradiol increased transcription 12.7-, 2.4-, and 3.8-fold, respectively. Increasing the spacing between the ERE and TATA sequence to three helical turns decreased the ability of the consensus ERE to activate transcription by 55% and increased the ability of the pS2 ERE to activate transcription by 35% but had no significant effect on vitellogenin B1 ERE2 activity. Further increasing the distance between the ERE and TATA sequence to 3.6 helical turns restored the activity of promoters containing the consensus ERE and pS2 ERE but decreased the activity of the promoter containing the relatively weak vitellogenin B1 ERE2. These data support the idea that 1) the affinity of ER for the ERE, 2) the location of an ERE within the promoter, and 3) the magnitude and orientation of DNA bends induced by binding of ER or other proteins are important in transcription activation of estrogen-responsive genes.
Mol Endocrinol 1996 Jun
PMID:Estrogen receptor affinity and location of consensus and imperfect estrogen response elements influence transcription activation of simplified promoters. 877 29

Polychlorinated biphenyls (PCBs) are one of the most widespread, persistent man-made products in the ecosystem giving rise to serious environmental contamination and potential hazard to health. The PCBs, in common with other compounds such as the dioxins, have been shown to exert some biological actions mediated through the aryl hydrocarbon receptor. Evidence for interaction of PCBs with other nuclear receptors has been sparse. Here we present evidence that 3,4,3',4'-tetrachlorobiphenyl (TCB) (PCB77), a PCB with high toxicity and significant bioaccumulation, can act as an estrogen with actions mediated through the estrogen receptor. Evidence is presented from multiple assay systems including 1) ligand binding to estrogen receptor in a competitive binding assay, 2) ligand ability to induce estrogen receptor binding to DNA, 3) ligand regulation of gene expression from a transfected exogenous (ERE-tk-CAT) or an endogenous (pS2) estrogen-regulated gene, 4) ligand regulation of cell growth in estrogen-dependent human breast cancer cell lines MCF7 and ZR-75-1, and 5) ligand activity in the immature mouse uterine weight bioassay in vivo. These results demonstrate that TCB (PCB77) can be included in the increasing list of environmental pollutants that possess the ability to mimic estrogen action and be termed an environmental estrogen. Since the concentrations of TCB used here (10(-9) M; 292 ng/liter) are not incompatible with levels of PCB/TCB found in human tissues, these results may have physiological relevance. Use of multiple approaches to study estrogenic action demonstrates that one congener can act as both an agonist and antagonist of estrogen action and that the magnitude of these effects can alter according to the molecular environment.
Mol Endocrinol 1996 Aug
PMID:3,4,3',4'-Tetrachlorobiphenyl acts as an estrogen in vitro and in vivo. 884 9

Estrogen responses of human breast cancer cell lines have frequently been shown to be promoted by insulin. We have examined the action of insulin, and its interaction with estradiol, in regulating the expression of the estrogen-induced genes, LIV-1 and pS2. Both hormones cause increases in mRNA levels of the two genes but do so by distinct mechanisms. The concentration of insulin required to produce this effect suggests that it is acting via its ability to bind to the IGF-1 receptor. Both insulin and estradiol exert their effects at the level of transcription. Induction by insulin is dependent upon continued protein synthesis whereas induction by estradiol is not. Induction by both insulin and estradiol is prevented by the pure antiestrogen. ICI 164384, indicating the requirement for an activatable estrogen receptor. Insulin does not stimulate LIV-1 expression via the androgen receptor. These results demonstrate that both estradiol and insulin can stimulate the transcription of these estrogen-inducible genes, by separate mechanisms both of which involve the estrogen receptor.
Mol Cell Endocrinol 1996 Jul 23
PMID:Insulin/IGF-1 modulation of the expression of two estrogen-induced genes in MCF-7 cells. 886 63

To understand better the antiestrogen-resistant phenotype that frequently develops in breast cancer patients receiving tamoxifen, we cultured MCF-7 breast cancer cells long-term (>1 yr) in the presence of the antiestrogen trans-hydroxytamoxifen (TOT) to generate a subline refractory to the growth-suppressive effects of TOT. This subline (designated MCF/TOT) showed growth stimulation, rather than inhibition, with TOT and diminished growth stimulation with estradiol (E2), yet remained as sensitive as the parental cells to growth suppression by another antiestrogen, ICI 164,384. Estrogen receptor (ER) levels were maintained at 40% of that in parent MCF-7 cells, but MCF/TOT cells failed to show an increase in progesterone receptor content in response to E2 or TOT treatment. In contrast, the MCF/TOT subline behaved like parental cells in terms of E2 and TOT regulation of ER and pS2 expression and transactivation of a transiently transfected estrogen-responsive gene construct. DNA sequencing of the hormone binding domain of the ER from both MCF-7 and MCF/TOT cells confirmed the presence of wild-type ER and exon 5 and exon 7 deletion splice variants, but showed no point mutations. Compared to the parental cells, the MCF/TOT subline showed reduced sensitivity to the growth-suppressive effects of retinoic acid and complete resistance to exogenous TGF-beta1. The altered growth responsiveness of MCF/TOT cells to TOT and TGF-beta1 was partly to fully reversible following TOT withdrawal for 16 weeks. Our findings underscore the fact that antiestrogen resistance is response-specific; that loss of growth suppression by TOT appears to be due to the acquisition of weak growth stimulation; and that resistance to TOT does not mean global resistance to other more pure antiestrogens such as ICI 164,384, implying that these antiestrogens must act by somewhat different mechanisms. The association of reduced retinoic acid responsiveness and insensitivity to exogenous TGF-beta with antiestrogen growth resistance in these cells supports the increasing evidence for interrelationships among cell regulatory pathways utilized by these three growth-suppressive agents in breast cancer cells. In addition, our findings indicate that one mechanism of antiestrogen resistance, as seen in MCF/TOT cells, may involve alterations in growth factor and other hormonal pathways that affect the ER response pathway.
J Steroid Biochem Mol Biol 1996 Oct
PMID:Response-specific antiestrogen resistance in a newly characterized MCF-7 human breast cancer cell line resulting from long-term exposure to trans-hydroxytamoxifen. 901 Mar 27

The mRNA levels of LIV-1 and pS2, two estrogen-responsive genes, are increased by the agents, cholera toxin (CT) plus 3-isobutyl-l-methylxanthine (IBMX), which cause an increase in cAMP in MCF-7 human breast cancer cells. The simultaneous addition of estradiol and CT/IBMX results in a synergistic induction of the two mRNAs. The changes in mRNA reflect changes in transcription of the two genes. Interestingly, the addition of CT/IBMX to estradiol not only causes a greater increase in transcription rate but the increase is longer-lasting that seen with the hormone alone. Stimulation of mRNA levels by CT/IBMX, but not by estradiol, was prevented by cycloheximide. Stimulation by both estradiol and by CT/IBMX was prevented by the antiestrogen, ICI 164387. Transcription of LIV-1 and pS2 genes is by both estradiol and cAMP, via separate mechanisms both requiring the estrogen receptor.
Mol Cell Endocrinol 1996 Nov 29
PMID:Interaction between estradiol and cAMP in the regulation of specific gene expression. 902 26

The estrogen receptor (ER) is a ligand-regulated transcription factor that acts at the promoters of estrogen-regulated genes to modulate their expression. In the present study, we examined three estrogen-regulated promoters, namely the rat progesterone receptor gene distal (PRD) and proximal (PRP) promoters and the human pS2 gene promoter, and observed marked differences in their sensitivity to stimulation by estrogen and repression of estrogen-stimulated transcription by antiestrogen (AE)-occupied ER. ER-containing MCF-7 human breast cancer cells were transfected with reporter gene constructs containing estrogen response elements upstream of the three gene promoters. In this system, PRP and PRD showed similar dose-response curves for stimulation by estradiol whereas pS2 was activated by even lower concentrations of estradiol. By contrast, PRD was much less sensitive to repression of estrogen-stimulated activity by all AEs studied, relative to the PRP and the pS2 promoters. Using deletion and mutational analysis, we have identified a transferable cis element at -131 to -94 bp in PRD that is involved in modulating the sensitivity of this promoter to both estrogens and AEs. The element reduced the magnitude of estrogen-stimulated activity, enhanced the ability of AEs to repress estrogen-stimulated activity, and elicited similiar effects when transferred to the promoter of another estrogen-responsive gene. Thus, removal of this region from PRD further accentuated the insensitivity of this promoter to AE while enhancing its sensitivity (both EC50 and fold induction) to estrogen. Gel mobility shift assays showed that proteins from nuclear extracts of MCF-7 cells interact with this element and that the binding of these proteins is inversely correlated with the transcriptional effectiveness of the ER. The findings demonstrate that a specific cis element from the promoter of an estrogen-responsive gene can alter the transcriptional activity of hormone and antihormone-occupied receptor bound at its response element near the promoter. Such ligand response modulatory elements, and changes in the levels and activity of factors that bind to such elements, may underlie the different sensitivities of steroid hormone-regulated genes to both hormones and antihormones.
Mol Endocrinol 1997 Mar
PMID:Identification of a novel transferable cis element in the promoter of an estrogen-responsive gene that modulates sensitivity to hormone and antihormone. 905 79

pNR-2/pS2 is a 60 residue extracellular protein, which was originally discovered in human breast cancer cells, and subsequently found in other tumours and normal gastric epithelial cells. We have determined the three-dimensional solution structure of a C58S mutant of human pNR-2/pS2 using 639 distance and 137 torsion angle constraints obtained from analysis of multidimensional NMR spectra. A series of simulated annealing calculations resulted in the unambiguous determination of the protein's disulphide bonding pattern and produced a family of 19 structures consistent with the constraints. The peptide contains a single "trefoil" sequence motif, a region of about 40 residues with a characteristic sequence pattern, which has been found, either singly or as a repeat, in about a dozen extracellular proteins. The trefoil domain contains three disulphide bonds, whose 1-5, 2-4 and 3-6 cysteine pairings form the structure into three closely packed loops with only a small amount of secondary structure, which consists of a short alpha-helix packed against a two-stranded antiparallel beta-sheet. The structure of the domain is very similar to those of the two trefoil domains that occur in porcine spasmolytic polypeptide (PSP), the only member of the trefoil family whose three-dimensional structure has been previously determined. Outside the trefoil domain, which forms the compact "head" of the molecule, the N and C-terminal strands are closely associated, forming an extended "tail", which has some beta-sheet character for part of its length and which becomes more disordered towards the termini as indicated by (15)N{(1)H} NOEs. We have considered the structural implications of the possible formation of a native C58-C58 disulphide-bonded homodimer. Comparison of the surface features of pNR-2/pS2 and PSP, and consideration of the sequences of the other human trefoil domains in the light of these structures, illuminates the possible role of specific residues in ligand/receptor binding.
J Mol Biol 1997 Mar 28
PMID:High-resolution solution structure of human pNR-2/pS2: a single trefoil motif protein. 909 35

The response of two endogenous, estrogen-induced genes, LIV-1 and pS2, to growth factor stimulation of MCF-7 cells was examined. Epidermal growth factor (EGF), transforming growth factor alpha (TGF alpha) and insulin-like growth factor-1 (IGF-1) were each able to induce an increase in the two mRNAs in the absence of estradiol, and their effects were additive to that of an optimally inducing concentration (10(-8) M) of the hormone. Induction by EGF and TGF alpha, but not by IGF-1, were also additive to induction by a saturating concentration (2 microg/ml) of insulin. TGFbeta, an antimitogenic growth factor for MCF-7 cells, did not induce LIV-1 or pS2 mRNA but inhibited induction by estradiol. Increases in mRNA were shown to reflect increases in specific gene transcription. Induction by growth factors, but not by estradiol, was dependent upon protein synthesis. Induction by both growth factors and estradiol was inhibited by the pure antiestrogen, ICI 164384 (ICI), and by the mixed agonist/antagonist, tamoxifen. Despite differences in patterns of expression in vivo and in vitro, both LIV-1 and pS2 appeared to be responsive to growth factors via a mechanism distinct from that of estradiol but requiring the estrogen receptor.
J Steroid Biochem Mol Biol 1997 Mar
PMID:Interaction between estradiol and growth factors in the regulation of specific gene expression in MCF-7 human breast cancer cells. 921 17

The estrogenic character of tamoxifen and raloxifene was studied on three different genes, an ERE-reporter construct and two endogenous genes, sex hormone binding globulin (SHBG) and pS2, in two variants of the human liver carcinoma cell line HepG2. On the ERE-reporter construct and the pS2 gene both tamoxifen and raloxifene acted as pure estrogen antagonists, whereas on the SHBG gene they functioned as partial estrogens/antiestrogens at concentrations below 1 microM and as full "agonists" at concentrations higher than 1 microM. The fold stimulatory effect of tamoxifen and raloxifene on SHBG protein expression was similar in the estrogen receptor (ER) expressing HepG2 cells (HepER3) and the parental non-ER expressing HepG2 cells at concentrations above 1 microM. In contrast, the 17beta-estradiol analogue moxestrol stimulated SHBG expression only in the HepER3 cells. Both tamoxifen and raloxifene had an additive effect to estrogen receptor-dependent SHBG gene expression in the HepER3 cells in the presence of saturating concentrations of moxestrol. However, a significant difference was observed in that a much higher concentration of moxestrol was required to see an additive effect of raloxifene compared to tamoxifen. The cytokine IL1-beta completely blocked the tamoxifen-dependent induction of SHBG gene expression in HepER3 cells, but only partly blocked the effect of moxestrol mediated by the ER. In conclusion, our results suggest that the mechanism for the liver-selective "estrogenic" character of tamoxifen and raloxifene is mediated by a non-ER dependent pathway.
J Steroid Biochem Mol Biol 1997 May
PMID:Characterization of the "estrogenicity" of tamoxifen and raloxifene in HepG2 cells: regulation of gene expression from an ERE controlled reporter vector versus regulation of the endogenous SHBG and PS2 genes. 936 98


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