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Zhang R, Dong Y, Liu Y, Moezzi D, Ghorbani S, Mirzaei R, Lozinski BM, Dunn JF, Yong VW, Xue M. Enhanced liver X receptor signalling reduces brain injury and promotes tissue regeneration following experimental intracerebral haemorrhage: roles of microglia/macrophages. Stroke Vasc Neurol 2023; 8:486-502. [PMID: 37137522 PMCID: PMC10800269 DOI: 10.1136/svn-2023-002331] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/20/2023] [Accepted: 04/20/2023] [Indexed: 05/05/2023] Open
Abstract
BACKGROUND Inflammation-exacerbated secondary brain injury and limited tissue regeneration are barriers to favourable prognosis after intracerebral haemorrhage (ICH). As a regulator of inflammation and lipid metabolism, Liver X receptor (LXR) has the potential to alter microglia/macrophage (M/M) phenotype, and assist tissue repair by promoting cholesterol efflux and recycling from phagocytes. To support potential clinical translation, the benefits of enhanced LXR signalling are examined in experimental ICH. METHODS Collagenase-induced ICH mice were treated with the LXR agonist GW3965 or vehicle. Behavioural tests were conducted at multiple time points. Lesion and haematoma volume, and other brain parameters were assessed using multimodal MRI with T2-weighted, diffusion tensor imaging and dynamic contrast-enhanced MRI sequences. The fixed brain cryosections were stained and confocal microscopy was applied to detect LXR downstream genes, M/M phenotype, lipid/cholesterol-laden phagocytes, oligodendrocyte lineage cells and neural stem cells. Western blot and real-time qPCR were also used. CX3CR1CreER: Rosa26iDTR mice were employed for M/M-depletion experiments. RESULTS GW3965 treatment reduced lesion volume and white matter injury, and promoted haematoma clearance. Treated mice upregulated LXR downstream genes including ABCA1 and Apolipoprotein E, and had reduced density of M/M that apparently shifted from proinflammatory interleukin-1β+ to Arginase1+CD206+ regulatory phenotype. Fewer cholesterol crystal or myelin debris-laden phagocytes were observed in GW3965 mice. LXR activation increased the number of Olig2+PDGFRα+ precursors and Olig2+CC1+ mature oligodendrocytes in perihaematomal regions, and elevated SOX2+ or nestin+ neural stem cells in lesion and subventricular zone. MRI results supported better lesion recovery by GW3965, and this was corroborated by return to pre-ICH values of functional rotarod activity. The therapeutic effects of GW3965 were abrogated by M/M depletion in CX3CR1CreER: Rosa26iDTR mice. CONCLUSIONS LXR agonism using GW3965 reduced brain injury, promoted beneficial properties of M/M and facilitated tissue repair correspondent with enhanced cholesterol recycling.
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Affiliation(s)
- Ruiyi Zhang
- Department of Cerebrovascular Diseases, The Second Affiliated Hospital of Zhengzhou University, Zhengzhou, Henan, China
- Academy of Medical Science, Zhengzhou University, Zhengzhou, Henan, China
- Hotchkiss Brain Institute and Department of Clinical Neurosciences, University of Calgary, Calgary, Alberta, Canada
| | - Yifei Dong
- Department of Biochemistry, Microbiology, & Immunology, College of Medicine, University of Saskatchewan, Saskatoon, Saskatchewan, Canada
| | - Yang Liu
- Department of Cerebrovascular Diseases, The Second Affiliated Hospital of Zhengzhou University, Zhengzhou, Henan, China
- Academy of Medical Science, Zhengzhou University, Zhengzhou, Henan, China
| | - Dorsa Moezzi
- Hotchkiss Brain Institute and Department of Clinical Neurosciences, University of Calgary, Calgary, Alberta, Canada
| | - Samira Ghorbani
- Hotchkiss Brain Institute and Department of Clinical Neurosciences, University of Calgary, Calgary, Alberta, Canada
| | - Reza Mirzaei
- Hotchkiss Brain Institute and Department of Clinical Neurosciences, University of Calgary, Calgary, Alberta, Canada
| | - Brian M Lozinski
- Hotchkiss Brain Institute and Department of Clinical Neurosciences, University of Calgary, Calgary, Alberta, Canada
| | - Jeff F Dunn
- Department of Radiology, University of Calgary, Calgary, Alberta, Canada
| | - V Wee Yong
- Hotchkiss Brain Institute and Department of Clinical Neurosciences, University of Calgary, Calgary, Alberta, Canada
| | - Mengzhou Xue
- Department of Cerebrovascular Diseases, The Second Affiliated Hospital of Zhengzhou University, Zhengzhou, Henan, China
- Academy of Medical Science, Zhengzhou University, Zhengzhou, Henan, China
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Gustafsson JÅ, Li XC, Suh JH, Lou X. A structural perspective of liver X receptors. VITAMINS AND HORMONES 2023; 123:231-247. [PMID: 37717986 DOI: 10.1016/bs.vh.2023.01.008] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/09/2023]
Abstract
Liver X receptors α and β are members of the nuclear receptor family, which comprise a flexible N-terminal domain, a DNA binding domain, a hinge linker, and a ligand binding domain. Liver X receptors are important regulators of cholesterol and lipid homeostasis by controlling the transcription of numerous genes. Key to their transcriptional role is synergetic interaction among the domains. DNA binding domain binds on DNA; ligand binding domain is a crucial switch to control the transcription activity through conformational change caused by ligand binding. The Liver X receptors form heterodimers with retinoid X receptor and then the liganded heterodimer may recruit other necessary transcription components to form an active transcription complex.
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Affiliation(s)
- Jan-Åke Gustafsson
- Department of Cell Biology and Biochemistry, Center for Nuclear Receptors and Cell Signaling, University of Houston, Houston, TX, United States; Department of Biosciences and Nutrition, Karolinska Institutet, Huddinge, Sweden.
| | - Xian Chang Li
- Immunobiology and Transplant Science Center and Department of Surgery, Houston Methodist Research Institute, Houston, TX, United States; Department of Surgery, Weill Cornell Medical College of Cornell University, New York, NY, United States
| | - Ji Ho Suh
- Department of Anesthesiology, McGovern Medical School, The University of Texas Health Science Center at Houston, Houston, TX, United States
| | - Xiaohua Lou
- Immunobiology and Transplant Science Center and Department of Surgery, Houston Methodist Research Institute, Houston, TX, United States.
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3
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Garcia-Ruiz C, Conde de la Rosa L, Ribas V, Fernandez-Checa JC. MITOCHONDRIAL CHOLESTEROL AND CANCER. Semin Cancer Biol 2021; 73:76-85. [PMID: 32805396 PMCID: PMC7882000 DOI: 10.1016/j.semcancer.2020.07.014] [Citation(s) in RCA: 18] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/09/2020] [Revised: 07/22/2020] [Accepted: 07/29/2020] [Indexed: 12/11/2022]
Abstract
Cholesterol is a crucial component of membrane bilayers that determines their physical and functional properties. Cells largely satisfy their need for cholesterol through the novo synthesis from acetyl-CoA and this demand is particularly critical for cancer cells to sustain dysregulated cell proliferation. However, the association between serum or tissue cholesterol levels and cancer development is not well established as epidemiologic data do not consistently support this link. While most preclinical studies focused on the role of total celular cholesterol, the specific contribution of the mitochondrial cholesterol pool to alterations in cancer cell biology has been less explored. Although low compared to other bilayers, the mitochondrial cholesterol content plays an important physiological function in the synthesis of steroid hormones in steroidogenic tissues or bile acids in the liver and controls mitochondrial function. In addition, mitochondrial cholesterol metabolism generates oxysterols, which in turn, regulate multiple pathways, including cholesterol and lipid metabolism as well as cell proliferation. In the present review, we summarize the regulation of mitochondrial cholesterol, including its role in mitochondrial routine performance, cell death and chemotherapy resistance, highlighting its potential contribution to cancer. Of particular relevance is hepatocellular carcinoma, whose incidence in Western countries had tripled in the past decades due to the obesity and type II diabetes epidemic. A better understanding of the role of mitochondrial cholesterol in cancer development may open up novel opportunities for cancer therapy.
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Affiliation(s)
- Carmen Garcia-Ruiz
- Department of Cell Death and Proliferation, Institute of Biomedical Research of Barcelona (IIBB), CSIC, Barcelona, Spain; Liver Unit, Hospital Clinic I Provincial de Barcelona, Instituto de Investigaciones Biomédicas August Pi i Sunyer (IDIBAPS), Barcelona, Spain; Center for the Study of Liver and Gastrointestinal Diseases (CIBERehd), Carlos III National Institute of Health, Madrid, Spain; Center for ALPD, Keck School of Medicine, University of Southern California, Los Angeles, CA, United States
| | - Laura Conde de la Rosa
- Department of Cell Death and Proliferation, Institute of Biomedical Research of Barcelona (IIBB), CSIC, Barcelona, Spain; Liver Unit, Hospital Clinic I Provincial de Barcelona, Instituto de Investigaciones Biomédicas August Pi i Sunyer (IDIBAPS), Barcelona, Spain; Center for the Study of Liver and Gastrointestinal Diseases (CIBERehd), Carlos III National Institute of Health, Madrid, Spain
| | - Vicent Ribas
- Department of Cell Death and Proliferation, Institute of Biomedical Research of Barcelona (IIBB), CSIC, Barcelona, Spain; Liver Unit, Hospital Clinic I Provincial de Barcelona, Instituto de Investigaciones Biomédicas August Pi i Sunyer (IDIBAPS), Barcelona, Spain; Center for the Study of Liver and Gastrointestinal Diseases (CIBERehd), Carlos III National Institute of Health, Madrid, Spain
| | - Jose C Fernandez-Checa
- Department of Cell Death and Proliferation, Institute of Biomedical Research of Barcelona (IIBB), CSIC, Barcelona, Spain; Liver Unit, Hospital Clinic I Provincial de Barcelona, Instituto de Investigaciones Biomédicas August Pi i Sunyer (IDIBAPS), Barcelona, Spain; Center for the Study of Liver and Gastrointestinal Diseases (CIBERehd), Carlos III National Institute of Health, Madrid, Spain; Center for ALPD, Keck School of Medicine, University of Southern California, Los Angeles, CA, United States
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Zhang Z, Chen H, Chen Z, Ding P, Ju Y, Gu Q, Xu J, Zhou H. Identify liver X receptor β modulator building blocks by developing a fluorescence polarization-based competition assay. Eur J Med Chem 2019; 178:458-467. [DOI: 10.1016/j.ejmech.2019.06.011] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2019] [Revised: 06/03/2019] [Accepted: 06/03/2019] [Indexed: 01/19/2023]
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Lipid reducing activity of novel cholic acid (CA) analogs: Design, synthesis and preliminary mechanism study. Bioorg Chem 2018; 80:396-407. [PMID: 29986186 DOI: 10.1016/j.bioorg.2018.07.002] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/19/2018] [Revised: 06/27/2018] [Accepted: 07/01/2018] [Indexed: 12/23/2022]
Abstract
Bile acids, initially discovered as endogenous ligands of farnesoid X receptor (FXR), play a central role in the regulation of triglyceride and cholesterol metabolism and have recently emerged as a privileged structure for interacting with nuclear receptors relevant to a large array of metabolic processes. In this paper, phenoxy containing cholic acid derivatives with excellent drug-likeness have been designed, synthesized, and assayed as agents against cholesterol accumulation in Raw264.7 macrophages. The most active compound 14b reduced total cholesterol accumulation in Raw264.7 cells up to 30.5% at non-toxic 10 μM and dosage-dependently attenuated oxLDL-induced foam cell formation. Western blotting and qPCR results demonstrate that 14b reduced both cholesterol and lipid in Raw264.7 cells through (1) increasing the expression of cholesterol transporters ABCA1 and ABCG1, (2) accelerating ApoA1-mediated cholesterol efflux. Through a cell-based luciferase reporter assay and molecular docking analysis, LXR was identified as the potential target for 14b. Interestingly, unlike conventional LXR agonist, 14b did not increase lipogenesis gene SREBP-1c expression. Overall, these diverse properties disclosed herein highlight the potential of 14b as a promising lead for further development of multifunctional agents in the therapy of cardiovascular disease.
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6
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Peng D, Hiipakka RA, Xie JT, Dai Q, Kokontis JM, Reardon CA, Getz GS, Liao S. A novel potent synthetic steroidal liver X receptor agonist lowers plasma cholesterol and triglycerides and reduces atherosclerosis in LDLR(-/-) mice. Br J Pharmacol 2011; 162:1792-804. [PMID: 21232031 DOI: 10.1111/j.1476-5381.2011.01202.x] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022] Open
Abstract
BACKGROUND AND PURPOSE Potent synthetic nonsteroidal liver X receptor (LXR) agonists like T0901317 induce triglyceridaemia and fatty liver, effects not observed with some natural and synthetic steroidal, relatively weak agonists of LXR. To determine if potency is responsible for the lack of side effects with some steroidal agonists, we investigated the in vivo effects of a novel steroidal LXR agonist, ATI-111, that is more potent than T0901317. EXPERIMENTAL APPROACH Eight week old male LDLR(-/-) mice fed an atherogenic diet were orally treated with vehicle or ATI-111 at 3 and 5 mg·kg(-1) ·day(-1) for 8 weeks, and effects on plasma and liver lipid levels, expression of genes involved in lipid metabolism and on atherogenesis were analysed. KEY RESULTS ATI-111 increased the expression of genes involved in lipid transport, such as ABCA1, ABCG1 and ABCG5/G8, in intestine and macrophages; decreased ABCG1, apoE; and slightly increased ABCA1 and ABCG5/G8 expression in liver. ATI-111 markedly increased sterol regulatory element-binding protein (SREBP)-1c mRNA in some tissues, whereas acetyl-coenzyme A carboxylase and fatty acid synthase expression was unaffected or only slightly increased in intestine and liver. ATI-111 inhibited the conversion of SREBP-1c precursor form to its active form. Compared with vehicle-treated mice, the levels of hepatic lipids and liver-secreted nascent lipoproteins were not altered, while a significant decrease in plasma cholesterol and triglyceride levels was observed in ATI-111-treated mice. ATI-111 significantly inhibited atherogenesis in three separate vascular sites. CONCLUSIONS AND IMPLICATIONS ATI-111 is a promising candidate for further development as a treatment of certain vascular diseases as it lacks the significant side effects associated with nonsteroidal LXR agonists, the induction of fatty liver and hypertriglyceridaemia.
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Affiliation(s)
- Dacheng Peng
- Ben May Department for Cancer Research, University of Chicago, Chicago, IL, USA
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7
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Chuu CP. Modulation of liver X receptor signaling as a prevention and therapy for colon cancer. Med Hypotheses 2011; 76:697-9. [DOI: 10.1016/j.mehy.2011.01.037] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/19/2010] [Accepted: 01/26/2011] [Indexed: 01/06/2023]
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8
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Pfeifer T, Buchebner M, Chandak PG, Patankar J, Kratzer A, Obrowsky S, Rechberger GN, Kadam RS, Kompella UB, Kostner GM, Kratky D, Levak-Frank S. Synthetic LXR agonist suppresses endogenous cholesterol biosynthesis and efficiently lowers plasma cholesterol. Curr Pharm Biotechnol 2011; 12:285-92. [PMID: 21190543 DOI: 10.2174/138920111794295774] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/28/2010] [Accepted: 06/13/2010] [Indexed: 11/22/2022]
Abstract
The liver X receptors (LXRs) are key regulators of genes involved in cholesterol homeostasis. Natural ligands and activators of LXRs are oxysterols. Numerous steroidal and non-steroidal synthetic LXR ligands are under development as potential drugs for individuals suffering from lipid disorders. N,N-dimethyl-3β-hydroxycholenamide (DMHCA) is a steroidal ligand of LXRs that exerts anti-atherogenic effects in apolipoprotein E-deficient mice without causing negative side effects such as liver steatosis or hypertriglyceridemia. In this report, we investigated the consequences of DMHCA treatment on cholesterol homeostasis in vivo and in vitro. Despite its hydrophobicity, DMHCA is readily absorbed by C57BL/6 mice and taken up by intestinal cells, the lung, heart and kidneys, but is undetectable in the brain. DMHCA significantly reduces cholesterol absorption and uptake in duodenum and jejunum of the small intestine and in turn leads to a reduction of plasma cholesterol by 24%. The most striking finding of this study is that DMHCA inhibited the enzyme 3β-hydroxysterol-Δ24-reductase resulting in an accumulation of desmosterol in the plasma and in feces. Thus, the reduction of plasma cholesterol was due to a block in the final step of cholesterol biosynthesis. Taken together, DMHCA is an interesting compound with properties distinct from other LXR ligands and might be used to study desmosterol-mediated effects in cells and tissues.
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Affiliation(s)
- Thomas Pfeifer
- Institute of Molecular Biology and Biochemistry, Medical University of Graz, Harrachgasse 21/3, Graz, Austria
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10
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Peng D, Hiipakka RA, Dai Q, Guo J, Reardon CA, Getz GS, Liao S. Antiatherosclerotic effects of a novel synthetic tissue-selective steroidal liver X receptor agonist in low-density lipoprotein receptor-deficient mice. J Pharmacol Exp Ther 2008; 327:332-42. [PMID: 18723776 DOI: 10.1124/jpet.108.142687] [Citation(s) in RCA: 54] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Liver X receptor (LXR) agonists have the potential to treat atherosclerosis based on their ability to enhance reverse cholesterol transport. However, their side effects, such as induction of liver lipogenesis and triglyceridemia, may limit their pharmaceutical development. In contrast to the nonsteroidal LXR agonist N-(2,2,2-trifluoroethyl)-N-[4-[2,2,2-trifluoro-1-hydroxy-1-(trifluoromethyl)ethyl]phenyl]-benzenesulfonamide (T0901317), 3alpha, 6alpha, 24-trihydroxy-24, 24-di(trifluoromethyl)-5beta-cholane (ATI-829), a novel potent synthetic steroidal LXR agonist, was a poor inducer of sterol regulatory element-binding protein 1c expression in hepatoma HepG2 cells, whereas both compounds increased ABCA1 expression in macrophage THP-1 cells. In male low-density lipoprotein receptor-deficient mice, ATI-829 selectively activated LXR target gene expression in mouse intestines and macrophages but not in the liver. A significant increase in liver triglyceride and plasma triglyceriderich small very low-density lipoprotein (VLDL) was observed in T0901317 but not ATI-829-treated mice. Compared with vehicle-treated mice, atherosclerosis development was significantly inhibited in the innominate artery after treatment with either compound. However, in the aortic root, inhibition of atherosclerosis was only observed in the right (right coronary artery-associated sinus) but not the left coronary-related sinus (left coronary artery-associated sinus; LC) of mice treated with either compound. Lesions in the innominate artery were less complex after treatment with either compound and contained mostly macrophage foam cells. In contrast, LC lesions were more complex and had a large collagen-positive fibrous cap and less macrophage foam cell area after treatment with either compound. The T0901317-induced hypertriglyceridemia was accompanied by an increase in small triglyceride-rich VLDL that may influence LXR agonist-mediated antiatherosclerotic effects at certain vascular sites. ATI-829, by selectively activating LXR in certain tissues without inducing hypertriglyceridemia, is a good candidate for drug development.
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Affiliation(s)
- Dacheng Peng
- Ben May Department for Cancer Research, University of Chicago, W334, 929 E. 57th Street, Chicago, IL 60637, USA
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11
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Lee JH, Gong H, Khadem S, Lu Y, Gao X, Li S, Zhang J, Xie W. Androgen deprivation by activating the liver X receptor. Endocrinology 2008; 149:3778-88. [PMID: 18450964 PMCID: PMC2488233 DOI: 10.1210/en.2007-1605] [Citation(s) in RCA: 52] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
Prostate cancer is the most commonly diagnosed and the second leading cause of cancer death in men. The androgens-androgen receptor signaling plays an important role in normal prostate development, as well as in prostatic diseases, such as benign hyperplasia and prostate cancer. Accordingly, androgen ablation has been the most effective endocrine therapy for hormone-dependent prostate cancer. Here, we report a novel nuclear receptor-mediated mechanism of androgen deprivation. Genetic or pharmacological activation of the liver X receptor (LXR) in vivo lowered androgenic activity by inducing the hydroxysteroid sulfotransferase 2A1, an enzyme essential for the metabolic deactivation of androgens. Activation of LXR also inhibited the expression of steroid sulfatase in the prostate, which may have helped to prevent the local conversion of sulfonated androgens back to active metabolites. Interestingly, LXR also induced the expression of selected testicular androgen synthesizing enzymes. At the physiological level, activation of LXR in mice inhibited androgen-dependent prostate regeneration in castrated mice. Treatment with LXR agonists inhibited androgen-dependent proliferation of prostate cancer cells in a LXR- and sulfotransferase 2A1-dependent manner. In summary, we have revealed a novel function of LXR in androgen homeostasis, an endocrine role distinct to the previously known sterol sensor function of this receptor. LXR may represent a novel therapeutic target for androgen deprivation, and may aid in the treatment and prevention of hormone-dependent prostate cancer.
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MESH Headings
- Androgens/biosynthesis
- Androgens/pharmacology
- Animals
- Benzoates/pharmacology
- Benzoates/therapeutic use
- Benzylamines/pharmacology
- Benzylamines/therapeutic use
- Cells, Cultured
- DNA-Binding Proteins/agonists
- DNA-Binding Proteins/genetics
- DNA-Binding Proteins/metabolism
- DNA-Binding Proteins/physiology
- Drug Resistance, Neoplasm/genetics
- Gene Expression Regulation, Enzymologic/drug effects
- Humans
- Hydroxycholesterols/pharmacology
- Hydroxycholesterols/therapeutic use
- Liver X Receptors
- Male
- Mice
- Mice, Inbred C57BL
- Mice, Transgenic
- Neoplasms, Hormone-Dependent/drug therapy
- Neoplasms, Hormone-Dependent/metabolism
- Orphan Nuclear Receptors
- Prostate/drug effects
- Prostate/physiology
- Prostatic Neoplasms/drug therapy
- Prostatic Neoplasms/metabolism
- Receptors, Cytoplasmic and Nuclear/agonists
- Receptors, Cytoplasmic and Nuclear/genetics
- Receptors, Cytoplasmic and Nuclear/metabolism
- Receptors, Cytoplasmic and Nuclear/physiology
- Regeneration/drug effects
- Sulfotransferases/genetics
- Testosterone/blood
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Affiliation(s)
- Jung Hoon Lee
- Center for Pharmacogenetics, University of Pittsburgh, Pittsburgh, Pennsylvania 15261, USA
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12
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Russell LE, Harrison WJ, Bahta AW, Zouboulis CC, Burrin JM, Philpott MP. Characterization of liver X receptor expression and function in human skin and the pilosebaceous unit. Exp Dermatol 2007; 16:844-52. [PMID: 17845217 DOI: 10.1111/j.1600-0625.2007.00612.x] [Citation(s) in RCA: 54] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
The nuclear receptors liver X receptor alpha (LXRalpha) and liver X-receptor beta (LXRbeta) have a well documented role in cholesterol homeostasis and lipid metabolism within tissues and cells including the liver, small intestine and macrophages. In keratinocytes, LXRs have been shown to up-regulate differentiation in vitro via increased transcription of proteins of the AP1 complex and to down-regulate proliferation in vivo. In this study, we provide a detailed description of the location and possible role of LXRs within human skin and its associated glands and appendages. Using RT-PCR, Western blotting and immunohistochemistry, we have demonstrated expression of LXRalpha and LXRbeta mRNA and proteins in whole human skin as well as within a range of primary and immortalized human cell lines derived from human skin, hair follicle and sebaceous glands. Furthermore, we have shown that synthetic LXR specific agonists GW683965 and TO901317 significantly inhibit cell proliferation in primary epidermal keratinocytes, immortalized N/TERT keratinocytes and the immortalized SZ95 sebocyte line, and significantly increase lipogenesis in SZ95 sebocytes. In addition, we showed that the synthetic agonist TO901317 significantly reduced hair growth, in vitro.
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Affiliation(s)
- Louise E Russell
- Centre for Cutaneous Research and Centre for Endocrinology, Bart's and The London Queen Mary's School of Medicine and Dentistry, Queen Mary College, University of London, London, UK
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13
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Chuu CP, Kokontis JM, Hiipakka RA, Liao S. Modulation of liver X receptor signaling as novel therapy for prostate cancer. J Biomed Sci 2007; 14:543-53. [PMID: 17372849 DOI: 10.1007/s11373-007-9160-8] [Citation(s) in RCA: 58] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/09/2007] [Accepted: 02/26/2007] [Indexed: 10/23/2022] Open
Abstract
Liver X receptors (LXRs) are important regulators of cholesterol, fatty acid, and glucose homeostasis. LXR agonists are effective for treatment of murine models of atherosclerosis, diabetes, and Alzheimer's disease. Recently we observed that LXR agonists suppressed proliferation of prostate and breast cancer cells in vitro and treatment of mice with the LXR agonist T0901317 suppressed the growth of prostate tumor xenografts. LXR agonists appear to cause G1 cell cycle arrest in cells by reducing expression of Skp2 and inducing the accumulation of p27(Kip). T0901317 induced expression of ATP-binding cassette transporter A1 (ABCA1) and delayed the progression of androgen-dependent human prostate tumor xenografts towards androgen-independency in mice. Phytosterols, the plant equivalent of mammalian cholesterol, have recently been shown to be agonists for LXRs. beta-Sitosterol and campesterol, the two most common phytosterols, suppressed proliferation of prostate and breast cancer cells. The anticancer activity of phytosterols may be due to LXR signaling. This review examines the potential use of LXR signaling as a therapeutic target in prostate and other cancers.
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Affiliation(s)
- Chih-Pin Chuu
- The Ben May Department for Cancer Research, The University of Chicago, 929 East 57th Street, CIS W325F, Chicago, IL 60637, USA
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14
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Nuclear Hormone Receptor Modulators for the Treatment of Diabetes and Dyslipidemia. ANNUAL REPORTS IN MEDICINAL CHEMISTRY 2006. [DOI: 10.1016/s0065-7743(06)41006-x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/03/2023]
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Quinet EM, Savio DA, Halpern AR, Chen L, Miller CP, Nambi P. Gene-selective modulation by a synthetic oxysterol ligand of the liver X receptor. J Lipid Res 2004; 45:1929-42. [PMID: 15292374 DOI: 10.1194/jlr.m400257-jlr200] [Citation(s) in RCA: 114] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Liver X receptors (LXRs) play key roles in the regulation of cholesterol homeostasis by limiting cholesterol accumulation in macrophages within arterial wall lesion sites by a mechanism that includes the upregulation of ATP binding cassette transporters. These atheroprotective properties distinguish LXRs as potential targets for pharmaceutical intervention in cardiovascular disease. Their associated activity for promoting lipogenesis and triglyceride accretion through the activation of sterol-response element binding protein 1c (SREBP-1c) expression, however, represents a potential proatherogenic liability. A newly characterized synthetic oxysterol, N,N-dimethyl-3beta-hydroxycholenamide (DMHCA), represents a gene-selective LXR modulator that mediates potent transcriptional activation of ABCA1 gene expression while exhibiting minimal effects on SREBP-1c both in vitro and in vivo in mice. DMHCA has the potential to stimulate cholesterol transport through the upregulation of LXR target genes, including ABCA1, in liver, small intestine, and peritoneal macrophages. Compared with known nonsteroidal LXR agonists, however, DMHCA exhibits only limited activity for increasing hepatic SREBP-1c mRNA and does not alter circulating plasma triglycerides. Cell-based studies also indicate that DMHCA enhances cholesterol efflux in macrophages and suggest a mechanism whereby this selective modulator can potentially inhibit cholesterol accumulation. DMHCA and related gene-selective ligands of LXR may have application to the study and treatment of atherosclerosis.
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Affiliation(s)
- Elaine M Quinet
- Departments of Cardiovascular/Metabolic Diseases, Wyeth Research, Collegeville, PA 19246, USA.
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16
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Peng D, Song C, Reardon CA, Liao S, Getz GS. Lipoproteins produced by ApoE-/- astrocytes infected with adenovirus expressing human ApoE. J Neurochem 2003; 86:1391-402. [PMID: 12950448 DOI: 10.1046/j.1471-4159.2003.01950.x] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
We have developed an astrocyte cell culture system that is attractive for the study of apoE structure and its impact on astrocyte lipoproteins and neuronal function. Primary astrocytes from apoE-/- mice were infected with adenovirus expressing apoE3 or apoE4 and the nascent lipoproteins secreted were characterized. The nascent apoE-containing astrocyte particles were predominantly the size of plasma high density lipoprotein (HDL). ApoE4, in contrast to apoE3, appeared to be distributed in two distinct lipoprotein peaks and the apoE4-containing lipoproteins contained significantly more radiolabeled triglyceride. On electron micrographs the astrocyte particles were both discoidal and spherical in shape with a prevalence of stacked discs in apoE3 particles, but single discs and larger spheres in apoE4 particles. The apoE4 discs were significantly wider than apoE3 discs. These properties of the astrocyte lipoproteins are similar to those obtained from apoE isoform transgenic mice. Astrocyte lipoproteins containing apoE3, but not apoE4, stimulated neurite outgrowth in Neuro-2a cells. These studies suggest that the isoform-specific effects of apoE lipoproteins may involve differences in particle size and composition. Finally we demonstrate the usefulness of this system by expressing a truncated apoE3 (delta202-299) mutant and show preliminary data indicating that a liver X receptor agonist promotes HDL output by the astrocytes without an increase in apoE in the media. This cell culture system is more flexible and allows for more rapid expression of apoE mutants.
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Affiliation(s)
- Dacheng Peng
- Department of Pathology, University of Chicago, Chicago, Illinois, USA
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17
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Abstract
Liver X receptors (LXRs) are members of the nuclear receptor superfamily that are involved in cholesterol and lipid metabolism. In addition to liver, the brain is another site where LXRs may control cholesterol homeostasis. In the brain, the regulation of cholesterol homeostasis is independent from other parts of the body, and its disturbance is associated with neurodegenerative disorders, such as Alzheimer's disease. We have used PCR-based suppressive subtractive cloning to identify new LXR target genes in brain cells. In this report, we show that farnesyl pyrophosphate synthase (FPPS) is a new target gene for LXR in astrocytes and neurons. Farnesyl pyrophosphate is an obligate intermediate for de novo cholesterol synthesis and a substrate for protein farnesylation. Stimulation of FPPS mRNA synthesis by an LXR agonist, Hypocholamide, was observed in several cell lines from the central nervous system. We identified a single putative direct repeat 4 (DR4) LXR response element in the FPPS promoter. In a reporter gene assay, LXR transactivated a reporter gene bearing a truncated FPPS promoter containing this DR4 cis-element but not if the DR4 element was mutated. Using gel-mobility shift assay, we further demonstrated the direct interaction between the LXR/retinoid X receptor (RXR) heterodimer and the response element. Taken together, our results indicate that LXRs directly regulate FPPS gene expression, and thus may play a role in modulating cholesterol synthesis in the brain.
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Affiliation(s)
- Junichi Fukuchi
- Department of Biochemistry and Molecular Biology, The Ben May Institute for Cancer Research, The University of Chicago, Box MC 6027, 5841 South Maryland Avenue, Chicago, IL 60637, USA
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18
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Lund EG, Menke JG, Sparrow CP. Liver X receptor agonists as potential therapeutic agents for dyslipidemia and atherosclerosis. Arterioscler Thromb Vasc Biol 2003; 23:1169-77. [PMID: 12615685 DOI: 10.1161/01.atv.0000056743.42348.59] [Citation(s) in RCA: 111] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
The recent identification of liver X receptors (LXR) as regulators of the cholesterol and phospholipid export pump ABCA1 has raised the possibility that LXR agonists could be developed as HDL-raising agents, possibly also acting on the artery wall to stimulate cholesterol efflux from lipid-laden macrophages. Presently several pharmaceutical companies are working to develop such compounds, which will require finding a path for separating these beneficial effects from the detrimental stimulation of triglyceride synthesis also inherent to LXR agonists. Other challenges to the drug development process include species differences, which makes prediction of in vivo effects of LXR agonists in humans difficult. This review summarizes the present state of knowledge on LXR as a drug target and discusses possible solutions for dissociating the favorable effects of LXR agonists from their unwanted effects.
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Affiliation(s)
- Erik G Lund
- Department of Atherosclerosis, Merck Research Laboratories, PO Box 2000, Rahway, NJ 0706, USA.
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Grefhorst A, Elzinga BM, Voshol PJ, Plösch T, Kok T, Bloks VW, van der Sluijs FH, Havekes LM, Romijn JA, Verkade HJ, Kuipers F. Stimulation of lipogenesis by pharmacological activation of the liver X receptor leads to production of large, triglyceride-rich very low density lipoprotein particles. J Biol Chem 2002; 277:34182-90. [PMID: 12097330 DOI: 10.1074/jbc.m204887200] [Citation(s) in RCA: 375] [Impact Index Per Article: 17.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023] Open
Abstract
The oxysterol-activated liver X receptor (LXR) provides a link between sterol and fatty acid metabolism; activation of LXR induces transcription of lipogenic genes. This study shows that induction of the lipogenic genes Srebp-1c, Fas, and Acc1 upon administration of the synthetic LXR agonist T0901317 to C57BL/6J mice (10 mg/kg/day, 4 days) is associated with massive hepatic steatosis along the entire liver lobule and a 2.5-fold increase in very low density lipoprotein-triglyceride (VLDL-TG) secretion. The increased VLDL-TG secretion was fully accounted for by formation of larger (129 +/- 9 nm versus 94 +/- 12 nm, a 2.5-fold increase of particle volume) TG-rich particles. Stimulation of VLDL-TG secretion did not lead to elevated plasma TG levels in C57BL/6J mice, indicating efficient particle metabolism and clearance. However, T0901317 treatment did lead to severe hypertriglyceridemia in mouse models of defective TG-rich lipoprotein clearance, i.e. APOE*3-Leiden transgenic mice (3.2-fold increase) and apoE-/- LDLr-/- double knockouts (12-fold increase). Incubation of rat hepatoma McA-RH7777 cells with T0901317 also resulted in intracellular TG accumulation and enhanced TG secretion. We conclude that, in addition to raising high density lipoprotein cholesterol concentrations, pharmacological LXR activation in mice leads to development of hepatic steatosis and secretion of atherogenic, large TG-rich VLDL particles.
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Affiliation(s)
- Aldo Grefhorst
- Laboratory of Pediatrics, Center for Liver, Digestive and Metabolic Diseases, University Hospital Groningen, Hanzeplein 1, 9713 RB Groningen, The Netherlands
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