| 1. |
- Figtree, G. A., et al.
(författare)
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Novel estrogen receptor alpha promoter polymorphism increases ventricular hypertrophic response to hypertension
- 2007
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Ingår i: Journal of Steroid Biochemistry and Molecular Biology. - : Elsevier BV. - 0960-0760 .- 1879-1220. ; 103:2, s. 110-118
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Tidskriftsartikel (refereegranskat)abstract
- Given the strong genetic contribution to blood pressure and left ventricular hypertrophy (LVH), and the influence of estrogen on these parameters, we hypothesized that polymorphisms in the estrogen receptor alpha (ERα) promoter may influence LVH. Three novel polymorphisms were identified upstream of the ERα alternatively spliced exon 1E, within sequence which demonstrated significant promoter activity in vitro. Demonstration of ERα E isoform expression in human ventricle by RT-PCR supported a possible functional role for the 1E novel polymorphisms in estrogen signaling in the heart. Indeed, G > A (-721 E) was significantly associated with LVH after controlling for systolic blood pressure and sex in a healthy population (n = 74), contributing to 23% of interventricular septum (IVS) width variance (p < 0.001) and 9.4% of left ventricular mass index (LVMI) variance (p = 0.035). In a separate hypertensive cohort, male carriers of the A allele (n = 8) had a 17% increase in IVS (95% CI: 6-28%) and a 19% increase in LVMI (3-34%) compared to GG homozygotes (n = 84). We conclude that a novel polymorphism in the promoter of a cardiac mRNA splice isoform of ERα is associated with LVH.
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| 2. |
- Johansson, Tobias, et al.
(författare)
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Neurosteroids alter glutamate-induced changes in neurite morphology of NG108-15 cells
- 2007
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Ingår i: Journal of Steroid Biochemistry and Molecular Biology. - : Elsevier BV. - 0960-0760 .- 1879-1220. ; 104:3-5, s. 215-219
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Tidskriftsartikel (refereegranskat)abstract
- Activation of the NMDA receptor leads to increased intracellular Ca2+ levels ([Ca2+]i) which induces outgrowth of and morphologic changes in the neurites of the NG108-15 cell line. This effect can be blocked by antagonists for this glutamate receptor subtype (e.g. ifenprodil or AP5). We have previously shown that nanomolar concentrations of various neurosteroids modulate ifenprodil binding to the NMDA receptor. To investigate whether this interaction affects the functioning of the receptor, we studied the effect of 24 and 48 h of pregnenolone sulphate (PS) or pregnanolone sulphate (3α5βS) on glutamate-stimulated NG108-15 cells. Unexpectedly, the neurosteroids themselves had an inhibitory effect on glutamate-induced changes in neurite patterns. This effect was comparable to that of ifenprodil or AP5. Moreover, the effect of combined treatment with 3α5βS and ifenprodil on neurite morphology indicated a functional interaction between the substances. Interestingly, PS induced cell detachment over time, an effect that was further enhanced by ifenprodil. Cell detachment was also seen after 48 h of treatment with 3α5βS; however, the effect was blocked by ifenprodil and weaker than that of PS. The interaction with the NR2B-selective antagonist ifenprodil indicates that this NMDA receptor subunit may be involved in neurosteroid-induced NG108-15 cell detachment.
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| 3. |
- Loinder, Kristina, 1963-, et al.
(författare)
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An LXXLL motif in nuclear receptor corepressor mediates ligand-induced repression of the thyroid stimulating hormone-β gene
- 2005
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Ingår i: Journal of Steroid Biochemistry and Molecular Biology. - : Elsevier BV. - 0960-0760 .- 1879-1220. ; 97:4, s. 322-327
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Tidskriftsartikel (refereegranskat)abstract
- Nuclear receptor corepressor (N-CoR) regulates gene expression through interaction with DNA-bound nuclear receptors, recruiting multicomponent repressor complexes to the sites of target genes. We recently reported the presence of an LXXLL motif in N-CoR, and showed that this motif interacts in vitro and in vivo with retinoic acid receptor α (RARα) and thyroid hormone receptor β (TRβ). Transient transfection experiments now suggest that TRβ and N-CoR act synergistically and may both be required for ligand-induced repression from the negative TR response element in the thyroid stimulating hormone-β (TSHβ) gene promoter. Mutation of the LXXLL motif in N-CoR abolished ligand-induced repression at this response element. Furthermore, in vitro binding of N-CoR to a complex between TRβ and the negative TR response element was strictly ligand-dependent. We conclude that N-CoR and TRβ cooperate in the regulation of the TSHβ gene and that the ligand-dependent repression is mediated by the LXXLL motif in N-CoR.
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| 4. |
- Tang, Wanjin, et al.
(författare)
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Estrogen-mediated regulation of CYP7B1 : a possible role for controlling DHEA levels in human tissues
- 2006
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Ingår i: Journal of Steroid Biochemistry and Molecular Biology. - : Elsevier BV. - 0960-0760 .- 1879-1220. ; 100:1-3, s. 42-51
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Tidskriftsartikel (refereegranskat)abstract
- The current study examines regulation of CYP7B1, a DHEA 7alpha-hydroxylase, by sex hormones. Transfection with estrogen receptor alpha and treatment with 17beta-estradiol in human embryonic kidney 293 cells significantly increased CYP7B1 catalytic activity and mRNA, and stimulated a human CYP7B1 reporter gene. Transfection with estrogen receptor beta showed similar but less significant effects. In the absence of receptors, 17beta-estradiol suppressed CYP7B1 activity, suggesting that estrogenic effects may be different in cells not expressing receptors. Quantitation of CYP7B1 mRNA in adult and fetal human tissues showed markedly higher CYP7B1 mRNA levels in fetal tissues compared with the corresponding adult ones, except in the liver. This indicates a tissue-specific, developmental regulation of CYP7B1 and suggests an important function for this enzyme in fetal life. DHEA secreted by fetal adrenals is an essential precursor for placental estrogen formation. Since CYP7B1 diverts DHEA from the sex hormone biosynthetic pathway, estrogen receptor-mediated up-regulation of CYP7B1 should lead to less DHEA available for sex hormone synthesis and may help to maintain normal levels of estrogens and androgens in human tissues, especially during fetal development. Regulation by estrogens may also be of importance in other processes where CYP7B1 is involved, including cholesterol homeostasis, cellular proliferation, and CNS function.
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| 5. |
- Tang, Wanjin, et al.
(författare)
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Involvement of the PI3K/Akt pathway in estrogen-mediated regulation of human CYP7B1 : identification of CYP7B1 as a novel target for PI3K/Akt and MAPK signalling
- 2008
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Ingår i: Journal of Steroid Biochemistry and Molecular Biology. - : Elsevier BV. - 0960-0760 .- 1879-1220. ; 112:1-3, s. 63-73
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Tidskriftsartikel (refereegranskat)abstract
- The steroid hydroxylase CYP7B1 metabolizes neurosteroids, cholesterol derivatives, and estrogen receptor (ER) ligands. Previous studies identified CYP7B1 as a target for regulation by estrogen. The present study examines the mechanism for estrogen-mediated regulation of the human CYP7B1 gene promoter. Treatment with LY294002, a specific inhibitor of phosphatidylinositol 3-kinase (PI3K), abolished ER-mediated up-regulation of a CYP7B1 promoter-luciferase reporter in HepG2 cells, whereas overexpression of PI3K or Akt significantly increased estrogenic up-regulation of CYP7B1. Overexpression of dominant-negative mutant Akt abolished ER-mediated stimulation of CYP7B1 in HepG2 cells. Data indicated no binding of ER to CYP7B1 promoter sequences, suggesting that ER interacts with the PI3K/Akt pathway without binding to the gene. At low ER levels, overexpression of Akt suppressed CYP7B1 promoter activity, suggesting that its effect on CYP7B1 is different when estrogens are absent. In HEK293 cells, CYP7B1 transcription was much less affected by Akt, indicating that the mechanism for up-regulation of CYP7B1 is different in different cell types. Other experiments indicated that MAPK signalling may affect basal CYP7B1 levels. The current results, indicating that regulation of CYP7B1 by ER can be mediated via the PI3K/Akt signal pathway, a regulatory pathway important for cellular survival and growth, suggest an important role for CYP7B1 in cellular growth, particularly in connection with estrogenic signalling.
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| 6. |
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| 7. |
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| 8. |
- Holinka, CF, et al.
(författare)
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Estetrol: a unique steroid in human pregnancy
- 2008
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Ingår i: The Journal of steroid biochemistry and molecular biology. - : Elsevier BV. - 0960-0760. ; 110:1-2, s. 138-143
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Tidskriftsartikel (refereegranskat)
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| 9. |
- Jansson, Agneta
(författare)
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17Beta-hydroxysteroid dehydrogenase enzymes and breast cancer
- 2009
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Ingår i: JOURNAL OF STEROID BIOCHEMISTRY AND MOLECULAR BIOLOGY. - : Elsevier BV. - 0960-0760. ; 114:1-2, s. 64-67
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Tidskriftsartikel (refereegranskat)abstract
- Sex steroids play an important role in the development and differentiation in several tissues. Biologically active hormones that are locally converted in endocrine organs in the tissue where they exert their effects without release into extracellular space is a field of endocrinology that has been called intracrinology. In pre-menopausal women the ovary is the main source of estrogens, but in post-menopausal women the estrogen production as main site of synthesis moves to peripheral tissues and almost all of the sex steroids are synthesised from precursors of adrenal origin. In breast cancer 60-80% of the tumors express high levels of oestrogen receptor (ER) alpha which gives estrogen a proliferative effect. Breast tumors tend to have a higher intratumoral estrogen concentration than normal breast tissue and plasma, and in situ synthesis and the metabolism of estrogens is believed to be of great importance for the development and progression of the disease. The activity of estrogen metabolizing enzymes in breast are mainly aromatase, estrone sulfatases and 17HSD enzymes. 17HSD1 and 17HSD2 are the family members known to be of main importance in breast cancer. High expression of 17HSD1 has been associated to poor prognosis in breast cancer and late relapse among patients with ER-positive tumors. One of the mechanisms behind high 17HSD1 expression is gene amplification. Low or absent expression of 17HSD2 is associated to decreased survival in ER-positive breast cancer. 17HSD14 is one of the latest discovered 17HSD enzymes, transfection of 17HSD14 in human breast cancer cells significantly decreased the levels of estradiol in the culture medium. Low expression of 17HSD14 mRNA expression in breast cancer was correlated to decreased survival. The understanding of intratumoral synthesis of sex steroids in breast cancer is crucial to understand the disease both in pre- and post-menopausal women. Further studies are desirable to state the direct role of these enzymes in breast cancer and which patients that may benefit from new therapeutic strategies targeting 17HSD enzymes. The new inhibitors targeting 17HSD1 have shown promising results in preclinical studies to have clinical potential in the future.
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| 10. |
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| 11. |
- Labrie, Fernand, et al.
(författare)
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Comparable amounts of sex steroids are made outside the gonads in men and women: Strong lesson for hormone therapy of prostate and breast cancer.
- 2009
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Ingår i: The Journal of steroid biochemistry and molecular biology. - : Elsevier BV. - 0960-0760. ; 113:1-2, s. 52-6
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Tidskriftsartikel (refereegranskat)abstract
- The objective of this study was comparison of circulating androgens and their metabolites as well as estrogens measured for the first time by a validated mass spectrometry technology in 60-80-year-old men and women of comparable age. Castration in men (n=34) reduces the total androgen pool by only about 60% as indicated by the decrease in the serum levels of the glucuronide metabolites of androgens compared to intact men (n=1302). Such data are in agreement with the 50 to 75% decrease in intraprostatic dihydrotestosterone (DHT) concentration after castration. Most interestingly, the same amounts of androgens and estrogens are found in postmenopausal women (n=369) and castrated men of comparable age. The most significant therapeutic implication of these findings is the absolute need to add a pure (nonsteroidal) antiandrogen to castration in men with prostate cancer in order to block the action of the 25 to 50% DHT left in the prostate after castration. Not adding an antiandrogen to castration in men treated for prostate cancer is equivalent to not prescribing a blocker of estrogens in women suffering from breast cancer because they are postmenopausal and have low circulating estradiol.
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