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Pandey M, Cuddihy G, Gordon JA, Cox ME, Wasan KM. Inhibition of Scavenger Receptor Class B Type 1 (SR-B1) Expression and Activity as a Potential Novel Target to Disrupt Cholesterol Availability in Castration-Resistant Prostate Cancer. Pharmaceutics 2021; 13:1509. [PMID: 34575583 PMCID: PMC8467449 DOI: 10.3390/pharmaceutics13091509] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/25/2021] [Revised: 09/04/2021] [Accepted: 09/08/2021] [Indexed: 02/07/2023] Open
Abstract
There have been several studies that have linked elevated scavenger receptor class b type 1 (SR-B1) expression and activity to the development and progression of castration-resistant prostate cancer (CRPC). SR-B1 facilitates the influx of cholesterol to the cell from lipoproteins in systemic circulation. This influx of cholesterol may be important for many cellular functions, including the synthesis of androgens. Castration-resistant prostate cancer tumors can synthesize androgens de novo to supplement the loss of exogenous sources often induced by androgen deprivation therapy. Silencing of SR-B1 may impact the ability of prostate cancer cells, particularly those of the castration-resistant state, to maintain the intracellular supply of androgens by removing a supply of cholesterol. SR-B1 expression is elevated in CRPC models and has been linked to poor survival of patients. The overarching belief has been that cholesterol modulation, through either synthesis or uptake inhibition, will impact essential signaling processes, impeding the proliferation of prostate cancer. The reduction in cellular cholesterol availability can impede prostate cancer proliferation through both decreased steroid synthesis and steroid-independent mechanisms, providing a potential therapeutic target for the treatment of prostate cancer. In this article, we discuss and highlight the work on SR-B1 as a potential novel drug target for CRPC management.
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Affiliation(s)
- Mitali Pandey
- Department of Urological Sciences, Faculty of Medicine, University of British Columbia, Vancouver Prostate Centre, Vancouver, BC V6T 1Z3, Canada; (M.P.); (M.E.C.)
| | - Grace Cuddihy
- College of Pharmacy and Nutrition, University of Saskatchewan, 104 Clinic Place, Saskatoon, SK S7N 2Z4, Canada;
| | - Jacob A. Gordon
- Oncology Bioscience, Oncology R&D, AstraZeneca, Boston, MA 02451, USA;
| | - Michael E. Cox
- Department of Urological Sciences, Faculty of Medicine, University of British Columbia, Vancouver Prostate Centre, Vancouver, BC V6T 1Z3, Canada; (M.P.); (M.E.C.)
| | - Kishor M. Wasan
- Department of Urological Sciences, Faculty of Medicine, University of British Columbia, Vancouver Prostate Centre, Vancouver, BC V6T 1Z3, Canada; (M.P.); (M.E.C.)
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Dockendorff C, Faloon PW, Yu M, Youngsaye W, Penman M, Nieland TJF, Nag PP, Lewis TA, Pu J, Bennion M, Negri J, Paterson C, Lam G, Dandapani S, Perez JR, Munoz B, Palmer MA, Schreiber SL, Krieger M. Indolinyl-Thiazole Based Inhibitors of Scavenger Receptor-BI (SR-BI)-Mediated Lipid Transport. ACS Med Chem Lett 2015; 6:375-380. [PMID: 26478787 PMCID: PMC4599563 DOI: 10.1021/ml500154q] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/17/2014] [Accepted: 02/02/2015] [Indexed: 01/14/2023] Open
Abstract
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A potent class of indolinyl-thiazole
based inhibitors of cellular
lipid uptake mediated by scavenger receptor, class B, type I (SR-BI)
was identified via a high-throughput screen of the National Institutes
of Health Molecular Libraries Small Molecule Repository (NIH MLSMR)
in an assay measuring the uptake of the fluorescent lipid DiI from
HDL particles. This class of compounds is represented by ML278 (17–11), a potent (average IC50 = 6 nM) and reversible inhibitor of lipid uptake via SR-BI. ML278
is a plasma-stable, noncytotoxic probe that exhibits moderate metabolic
stability, thus displaying improved properties for in vitro and in
vivo studies. Strikingly, ML278 and previously described inhibitors
of lipid transport share the property of increasing the binding of
HDL to SR-BI, rather than blocking it, suggesting there may be similarities
in their mechanisms of action.
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Affiliation(s)
- Chris Dockendorff
- Center for the Science of Therapeutics, Broad Institute, 7 Cambridge Center, Cambridge, Massachusetts 02142, United States
- Department of Chemistry, Marquette University, Milwaukee, Wisconsin 53201-1881, United States
| | - Patrick W. Faloon
- Center for the Science of Therapeutics, Broad Institute, 7 Cambridge Center, Cambridge, Massachusetts 02142, United States
| | - Miao Yu
- Department of Biology, Massachusetts Institute of Technology, 77 Massachusetts Avenue, Cambridge, Massachusetts 02139, United States
| | - Willmen Youngsaye
- Center for the Science of Therapeutics, Broad Institute, 7 Cambridge Center, Cambridge, Massachusetts 02142, United States
| | - Marsha Penman
- Department of Biology, Massachusetts Institute of Technology, 77 Massachusetts Avenue, Cambridge, Massachusetts 02139, United States
| | - Thomas J. F. Nieland
- Center for the Science of Therapeutics, Broad Institute, 7 Cambridge Center, Cambridge, Massachusetts 02142, United States
- Department of Biology, Massachusetts Institute of Technology, 77 Massachusetts Avenue, Cambridge, Massachusetts 02139, United States
| | - Partha P. Nag
- Center for the Science of Therapeutics, Broad Institute, 7 Cambridge Center, Cambridge, Massachusetts 02142, United States
| | - Timothy A. Lewis
- Center for the Science of Therapeutics, Broad Institute, 7 Cambridge Center, Cambridge, Massachusetts 02142, United States
| | - Jun Pu
- Center for the Science of Therapeutics, Broad Institute, 7 Cambridge Center, Cambridge, Massachusetts 02142, United States
| | - Melissa Bennion
- Center for the Science of Therapeutics, Broad Institute, 7 Cambridge Center, Cambridge, Massachusetts 02142, United States
| | - Joseph Negri
- Center for the Science of Therapeutics, Broad Institute, 7 Cambridge Center, Cambridge, Massachusetts 02142, United States
| | - Conor Paterson
- Center for the Science of Therapeutics, Broad Institute, 7 Cambridge Center, Cambridge, Massachusetts 02142, United States
| | - Garrett Lam
- Center for the Science of Therapeutics, Broad Institute, 7 Cambridge Center, Cambridge, Massachusetts 02142, United States
| | - Sivaraman Dandapani
- Center for the Science of Therapeutics, Broad Institute, 7 Cambridge Center, Cambridge, Massachusetts 02142, United States
| | - José R. Perez
- Center for the Science of Therapeutics, Broad Institute, 7 Cambridge Center, Cambridge, Massachusetts 02142, United States
| | - Benito Munoz
- Center for the Science of Therapeutics, Broad Institute, 7 Cambridge Center, Cambridge, Massachusetts 02142, United States
| | - Michelle A. Palmer
- Center for the Science of Therapeutics, Broad Institute, 7 Cambridge Center, Cambridge, Massachusetts 02142, United States
| | - Stuart L. Schreiber
- Center for the Science of Therapeutics, Broad Institute, 7 Cambridge Center, Cambridge, Massachusetts 02142, United States
- Howard Hughes Medical Institute, Broad Institute, 7 Cambridge Center, Cambridge, Massachusetts 02142, United States
| | - Monty Krieger
- Department of Biology, Massachusetts Institute of Technology, 77 Massachusetts Avenue, Cambridge, Massachusetts 02139, United States
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Exoplasmic cysteine Cys384 of the HDL receptor SR-BI is critical for its sensitivity to a small-molecule inhibitor and normal lipid transport activity. Proc Natl Acad Sci U S A 2011; 108:12243-8. [PMID: 21746906 DOI: 10.1073/pnas.1109078108] [Citation(s) in RCA: 42] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
The HDL receptor, scavenger receptor, class B, type I (SR-BI), is a homooligomeric cell surface glycoprotein that controls HDL structure and metabolism by mediating the cellular selective uptake of lipids, mainly cholesteryl esters, from HDL. The mechanism underlying SR-BI-mediated lipid transfer, which differs from classic receptor-mediated endocytosis, involves a two-step process (binding followed by lipid transport) that is poorly understood. Our previous structure/activity analysis of the small-molecule inhibitor blocker of lipid transport 1 (BLT-1), which potently (IC(50) ∼ 50 nM) blocks SR-BI-mediated lipid transport, established that the sulfur in BLT-1's thiosemicarbazone moiety was essential for activity. Here we show that BLT-1 is an irreversible inhibitor of SR-BI, raising the possibility that cysteine(s) in SR-BI interact with BLT-1. Mass spectrometric analysis of purified SR-BI showed two of its six exoplasmic cysteines have free thiol groups (Cys251 and Cys384). Converting Cys384 (but not Cys251) to serine resulted in complete BLT-1 insensitivity, establishing that the unique molecular target of BLT-1 inhibition of cellular SR-BI dependent lipid transport is SR-BI itself. The C384S substitution reduced the receptor's intrinsic lipid uptake activity by approximately 60% without dramatically altering its surface expression, homooligomerization, or HDL binding. Thus, a small-molecule screening approach identified a key residue in SR-BI involved in lipid transport, providing a powerful springboard into the analyses of the structure and mechanism of SR-BI, and highlighting the power of this approach for such analyses.
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Toth PP. Pharmacomodulation of high-density lipoprotein metabolism as a therapeutic intervention for atherosclerotic disease. Curr Cardiol Rep 2010; 12:481-7. [PMID: 20740329 DOI: 10.1007/s11886-010-0136-3] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/15/2023]
Abstract
The high-density lipoproteins (HDLs) are produced by the liver and small intestine as well as on the surface of lipid-enriched macrophages in the subendothelial space of arterial walls. Unlike the apo B100-containing lipoproteins, the HDLs are uniquely antiatherogenic. Based on prospective observational studies performed throughout the world, there is a consistent inverse relationship between serum levels of HDLs and risk for cardiovascular events: low levels of high-density lipoprotein-cholesterol (HDL-C) are associated with increased risk, whereas high levels are usually associated with reduced risk for myocardial infarction, ischemic stroke, and cardiovascular mortality. Post hoc analyses of a number of studies using statins and fibrates have shown that raising serum HDL-C correlates with a reduction in risk for cardiovascular morbidity and mortality. Given these observations, enormous resources are being committed to the development of novel means by which to pharmacologically increase rates of HDL biosynthesis, modulate the functionality of HDL, and to promote reverse cholesterol transport with intravenous infusions of HDL particles.
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Affiliation(s)
- Peter P Toth
- Sterling Rock Falls Clinic, 101 East Miller Road, Sterling, IL 61081, USA.
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Masson D, Koseki M, Ishibashi M, Larson CJ, Miller SG, King BD, Tall AR. Increased HDL cholesterol and apoA-I in humans and mice treated with a novel SR-BI inhibitor. Arterioscler Thromb Vasc Biol 2009; 29:2054-60. [PMID: 19815817 DOI: 10.1161/atvbaha.109.191320] [Citation(s) in RCA: 66] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
OBJECTIVE Increasing HDL levels is a potential strategy for the treatment of atherosclerosis. METHODS AND RESULTS ITX5061, a molecule initially characterized as a p38 MAPK inhibitor, increased HDL-C levels by 20% in a human population of hypertriglyceridemic subjects with low HDL levels. ITX5061 also moderately increased apoA-I but did not affect VLDL/LDL cholesterol or plasma triglyceride concentrations. ITX5061 increased HDL-C in WT and human apoA-I transgenic mice, and kinetic experiments showed that ITX5061 decreased the fractional catabolic rate of HDL-CE and reduced its hepatic uptake. In transfected cells, ITX5061 inhibited SR-BI-dependent uptake of HDL-CE. Moreover, ITX5061 failed to increase HDL-C levels in SR-BI(-/-) mice. To assess effects on atherosclerosis, ITX5061 was given to atherogenic diet-fed Ldlr(+/-) mice with or without CETP expression for 18 weeks. In both the control and CETP-expressing groups, ITX5061-treated mice displayed reductions of early atherosclerotic lesions in the aortic arch -40%, P<0.05), and a nonsignificant trend to reduced lesion area in the proximal aorta. CONCLUSIONS Our data indicate that ITX5061 increases HDL-C levels by inhibition of SR-BI activity. This suggests that pharmacological inhibition of SR-BI has the potential to raise HDL-C and apoA-I levels without adverse effects on VLDL/LDL cholesterol levels in humans.
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Affiliation(s)
- David Masson
- Division of Molecular Medicine, Department of Medicine, Columbia University, New York, USA.
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Nieland TJF, Shaw JT, Jaipuri FA, Duffner JL, Koehler AN, Banakos S, Zannis VI, Kirchhausen T, Krieger M. Identification of the molecular target of small molecule inhibitors of HDL receptor SR-BI activity. Biochemistry 2007; 47:460-72. [PMID: 18067275 DOI: 10.1021/bi701277x] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
Scavenger receptor, class B, type I (SR-BI), controls high-density lipoprotein (HDL) metabolism by mediating cellular selective uptake of lipids from HDL without the concomitant degradation of the lipoprotein particle. We previously identified in a high-throughput chemical screen of intact cells five compounds (BLT-1-5) that inhibit SR-BI-dependent lipid transport from HDL, but do not block HDL binding to SR-BI on the cell surface. Although these BLTs are widely used to examine the diverse functions of SR-BI, their direct target(s), SR-BI itself or some other component of the SR-BI pathway, has not been identified. Here we show that SR-BI in the context of a membrane lipid environment is the target of BLT-1, -3, -4, and -5. The analysis using intact cells and an in vitro system of purified SR-BI reconstituted into liposomes was aided by information derived from structure-activity relationship (SAR) analysis of the most potent of these BLTs, the thiosemicarbazone BLT-1. We found that the sulfur atom of BLT-1 was crucially important for its inhibitory activity, because changing it to an oxygen atom resulted in the isostructural, but essentially inactive, semicarbazone derivative BLT-1sc. SAR analysis also established the importance of BLT-1's hydrophobic tail. BLTs and their corresponding inactive compounds can be used to explore the mechanism and function of SR-BI-mediated selective lipid uptake in diverse mammalian experimental models. Consequently, BLTs may help determine the therapeutic potential of SR-BI-targeted pharmaceutical drugs.
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Affiliation(s)
- Thomas J F Nieland
- Department of Biology, Massachusetts Institute of Technology, Room 68-483, 77 Massachusetts Avenue, Cambridge, Massachusetts 02139, USA
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Nieland TJF, Shaw JT, Jaipuri FA, Maliga Z, Duffner JL, Koehler AN, Krieger M. Influence of HDL-cholesterol-elevating drugs on the in vitro activity of the HDL receptor SR-BI. J Lipid Res 2007; 48:1832-45. [PMID: 17533223 DOI: 10.1194/jlr.m700209-jlr200] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Treatment of atherosclerotic disease often focuses on reducing plasma LDL-cholesterol or increasing plasma HDL-cholesterol. We examined in vitro the effects on HDL receptor [scavenger receptor class B type I (SR-BI)] activity of three classes of clinical and experimental plasma HDL-cholesterol-elevating compounds: niacin, fibrates, and HDL376. Fenofibrate (FF) and HDL376 were potent (IC(50) approximately 1 microM), direct inhibitors of SR-BI-mediated lipid transport in cells and in liposomes reconstituted with purified SR-BI. FF, a prodrug, was a more potent inhibitor of SR-BI than an activator of peroxisome proliferator-activated receptor alpha, a target of its active fenofibric acid (FFA) derivative. Nevertheless, FFA, four other fibrates (clofibrate, gemfibrozil, ciprofibrate, and bezafibrate), and niacin had little, if any, effect on SR-BI, suggesting that they do not directly target SR-BI in vivo. However, similarities of HDL376 treatment and SR-BI gene knockout on HDL metabolism in vivo (increased HDL-cholesterol and HDL particle sizes) and structure-activity relationship analysis suggest that SR-BI may be a target of HDL376 in vivo. HDL376 and other inhibitors may help elucidate SR-BI function in diverse mammalian models and determine the therapeutic potential of SR-BI-directed pharmaceuticals.
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Affiliation(s)
- Thomas J F Nieland
- Department of Biology, Massachusetts Institute of Technology, Cambridge, MA 02139, USA
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