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Reimão JQ, Pita Pedro DP, Coelho AC. The preclinical discovery and development of oral miltefosine for the treatment of visceral leishmaniasis: a case history. Expert Opin Drug Discov 2020; 15:647-658. [PMID: 32202449 DOI: 10.1080/17460441.2020.1743674] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/24/2022]
Abstract
INTRODUCTION Visceral leishmaniasis (VL) is a vector-borne disease caused by Leishmania donovani or Leishmania infantum. Closely related to poverty, VL is fatal and represents one of the main burdens on public health in developing countries. Treatment of VL relies exclusively on chemotherapy, a strategy still experiencing numerous limitations. Miltefosine (MF) has been used in the chemotherapy of VL in some endemic areas, and has been expanded to other regions, being considered crucial in eradication programs. AREAS COVERED This article reviews the most relevant preclinical and clinical aspects of MF, its mechanism of action and resistance to Leishmania parasites, as well as its limitations. The authors also give their perspectives on the treatment of VL. EXPERT OPINION The discovery of MF represented an enormous advance in the chemotherapy of VL, since it was the first oral drug for this neglected disease. Beyond selection of resistant parasites due to drug pressure, several other factors can lead to treatment failure such as, for example, factors intrinsic to the host, parasite and the drug itself. Although its efficacy as a monotherapy has reduced over recent years, MF is still an important alternative in VL chemotherapy, especially when used in combination with other drugs.
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Affiliation(s)
- Juliana Q Reimão
- Departamento de Morfologia e Patologia Básica, Faculdade de Medicina de Jundiaí , Jundiaí, Brazil
| | - Débora P Pita Pedro
- Departamento de Morfologia e Patologia Básica, Faculdade de Medicina de Jundiaí , Jundiaí, Brazil
| | - Adriano C Coelho
- Departamento de Biologia Animal, Instituto de Biologia, Universidade Estadual de Campinas , Campinas, Brazil
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Morotti ALM, Martins-Teixeira MB, Carvalho I. Protozoan Parasites Glycosylphosphatidylinositol Anchors: Structures, Functions and Trends for Drug Discovery. Curr Med Chem 2019; 26:4301-4322. [PMID: 28748758 DOI: 10.2174/0929867324666170727110801] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/2017] [Revised: 07/12/2017] [Accepted: 07/12/2017] [Indexed: 11/22/2022]
Abstract
BACKGROUND Glycosylphosphatidylinositol (GPI) anchors are molecules located on cell membranes of all eukaryotic organisms. Proteins, enzymes, and other macromolecules which are anchored by GPIs are essential elements for interaction between cells, and are widely used by protozoan parasites when compared to higher eukaryotes. METHODS More than one hundred references were collected to obtain broad information about mammalian and protozoan parasites' GPI structures, biosynthetic pathways, functions and attempts to use these molecules as drug targets against parasitic diseases. Differences between GPI among species were compared and highlighted. Strategies for drug discovery and development against protozoan GPI anchors were discussed based on what has been reported on literature. RESULTS There are many evidences that GPI anchors are crucial for parasite's survival and interaction with hosts' cells. Despite all GPI anchors contain a conserved glycan core, they present variations regarding structural features and biosynthetic pathways between organisms, which could offer adequate selectivity to validate GPI anchors as drug targets. Discussion was developed with focus on the following parasites: Trypanosoma brucei, Trypanosoma cruzi, Leishmania, Plasmodium falciparum and Toxoplasma gondii, causative agents of tropical neglected diseases. CONCLUSION This review debates the main variances between parasitic and mammalian GPI anchor biosynthesis and structures, as well as clues for strategic development for new anti-parasitic therapies based on GPI anchors.
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Affiliation(s)
- Ana Luísa Malaco Morotti
- School of Pharmaceutical Sciences of Ribeirao Preto - University of Sao Paulo, Sao Paulo, Brazil
| | | | - Ivone Carvalho
- School of Pharmaceutical Sciences of Ribeirao Preto - University of Sao Paulo, Sao Paulo, Brazil
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Ríos-Marco P, Marco C, Gálvez X, Jiménez-López JM, Carrasco MP. Alkylphospholipids: An update on molecular mechanisms and clinical relevance. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2017; 1859:1657-1667. [PMID: 28238819 DOI: 10.1016/j.bbamem.2017.02.016] [Citation(s) in RCA: 47] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/17/2016] [Revised: 02/20/2017] [Accepted: 02/21/2017] [Indexed: 11/16/2022]
Abstract
Alkylphospholipids (APLs) represent a new class of drugs which do not interact directly with DNA but act on the cell membrane where they accumulate and interfere with lipid metabolism and signalling pathways. This review summarizes the mode of action at the molecular level of these compounds. In this sense, a diversity of mechanisms has been suggested to explain the actions of clinically-relevant APLs, in particular, in cancer treatment. One consistently reported finding is that APLs reduce the biosynthesis of phosphatidylcholine (PC) by inhibiting the rate-limiting enzyme CTP:phosphocholine cytidylyltransferase (CT). APLs also alter intracellular cholesterol traffic and metabolism in human tumour-cell lines, leading to an accumulation of cholesterol inside the cell. An increase in cholesterol biosynthesis associated with a decrease in the synthesis of choline-containing phospholipids and cholesterol esterification leads to a change in the free-cholesterol:PC ratio in cells exposed to APLs. Akt phosphorylation status after APL exposure shows that this critical regulator for cell survival is modulated by changes in cholesterol levels induced in the plasma membrane by these lipid analogues. Furthermore, APLs produce cell ultrastructural alterations with an abundant autophagic vesicles and autolysosomes in treated cells, indicating an interference of autophagy process after APL exposure. Thus, antitumoural APLs interfere with the proliferation of tumour cells via a complex mechanism involving phospholipid and cholesterol metabolism, interfere with lipid-dependent survival-signalling pathways and autophagy. Although APLs also exert antiparasitic, antibacterial, and antifungal effects, in this review we provide a summary of the antileishmanial activity of these lipid analogues. This article is part of a Special Issue entitled: Membrane Lipid Therapy: Drugs Targeting Biomembranes edited by Pablo V. Escribá.
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Affiliation(s)
- Pablo Ríos-Marco
- Department of Biochemistry and Molecular Biology I, Faculty of Sciences, University of Granada, Av. Fuentenueva s/n, Granada 18001, Spain
| | - Carmen Marco
- Department of Biochemistry and Molecular Biology I, Faculty of Sciences, University of Granada, Av. Fuentenueva s/n, Granada 18001, Spain
| | - Xiomara Gálvez
- Department of Biochemistry and Molecular Biology I, Faculty of Sciences, University of Granada, Av. Fuentenueva s/n, Granada 18001, Spain
| | - José M Jiménez-López
- Department of Biochemistry and Molecular Biology I, Faculty of Sciences, University of Granada, Av. Fuentenueva s/n, Granada 18001, Spain.
| | - María P Carrasco
- Department of Biochemistry and Molecular Biology I, Faculty of Sciences, University of Granada, Av. Fuentenueva s/n, Granada 18001, Spain.
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Pleiotropic effects of antitumour alkylphospholipids on cholesterol transport and metabolism. Exp Cell Res 2015; 340:81-90. [PMID: 26712518 DOI: 10.1016/j.yexcr.2015.12.012] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/16/2015] [Revised: 12/15/2015] [Accepted: 12/18/2015] [Indexed: 11/20/2022]
Abstract
BACKGROUND Alkylphospholipid (APL) analogs are a new class of membrane-directed synthetic compounds with a variety of biological actions and clinical applications. In particular, these agents are promising candidates in cancer treatment. We have demonstrated that after prolonged treatment APLs alter intracellular cholesterol traffic and metabolism in human tumor-cell lines, leading to an accumulation of cholesterol inside the cell. After further investigation concerning the mode of action of APLs, we have explored the influence of several APLs on novel aspects of cholesterol and lipoprotein homeostasis using hepatoma HepG2 cells and THP1-derived macrophages. METHODS Quantitative real-time PCR analysis with a pathway-focused PCR array system was performed to measure relative changes in the mRNA expression of a number of genes related to cholesterol transport and metabolism. We compared the gene-expression profiles of HepG2 cells treated with miltefosine, edelfosine or perifosine for 6h and 24h with the profile of control cells. We also analysed particular genes of interest in both HepG2 and macrophage-like THP1 cells using specific PCR assays. Immunoblots were used to confirm protein-expression changes. Measurement of ABCA1-mediated cholesterol efflux was determined using apoA1 as cholesterol acceptor. RESULTS We found global changes in gene-expression patterns to maintain cholesterol homeostasis after exposure of cells to APLs. The pathways for cholesterol biosynthesis and LDL-cholesterol uptake were both transcriptionally upregulated by the three APLs assayed. Conversely, major pathways involved in the catabolism of cholesterol to bile acids and lipoprotein-associated cholesterol export were impaired after APL incubation, which may well contribute to the higher cell-cholesterol levels induced by these compounds. CONCLUSION Incubation of cells with different APLs stimulated cholesterol biosynthesis and uptake at the same time as it depressed common pathways for excess cholesterol removal in tumor cells, ultimately leading to altered cholesterol homeostasis.
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Zinrajh D, Hörl G, Jürgens G, Marc J, Sok M, Cerne D. Increased phosphatidylethanolamine N-methyltransferase gene expression in non-small-cell lung cancer tissue predicts shorter patient survival. Oncol Lett 2014; 7:2175-2179. [PMID: 24932311 PMCID: PMC4049682 DOI: 10.3892/ol.2014.2035] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/04/2013] [Accepted: 03/14/2014] [Indexed: 01/31/2023] Open
Abstract
Lipid mobilization is of great importance for tumor growth and studies have suggested that cancer cells exhibit abnormal choline phospholipid metabolism. In the present study, we hypothesized that phosphatidylethanolamine N-methyltransferase (PEMT) gene expression is increased in non-small-cell lung cancer (NSCLC) tissues and that increased gene expression acts as a predictor of shorter patient survival. Forty-two consecutive patients with resected NSCLC were enrolled in this study. Paired samples of lung cancer tissues and adjacent non-cancer lung tissues were collected from resected specimens for the estimation of PEMT expression. SYBR Green-based real-time polymerase chain reaction was used for quantification of PEMT mRNA in lung cancer tissues. Lipoprotein lipase (LPL) and fatty acid synthase (FASN) activities had already been measured in the same tissues. During a four-year follow-up, 21 patients succumbed to tumor progression. One patient did not survive due to non-cancer reasons and was not included in the analysis. Cox regression analysis was used to assess the prognostic value of PEMT expression. Our findings show that elevated PEMT expression in the cancer tissue, relative to that in the adjacent non-cancer lung tissue, predicts shorter patient survival independently of standard prognostic factors and also independently of increased LPL or FASN activity, the two other lipid-related predictors of shorter patient survival. These findings suggest that active phosphatidylcholine and/or choline metabolism are essential for tumor growth and progression.
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Affiliation(s)
- David Zinrajh
- Chair of Clinical Biochemistry, Faculty of Pharmacy, University of Ljubljana, SI-1000 Ljubljana, Slovenia
| | - Gerd Hörl
- Department of Physiological Chemistry, Center for Physiological Medicine, Medical University of Graz, A-8010 Graz, Austria
| | - Günther Jürgens
- Department of Physiological Chemistry, Center for Physiological Medicine, Medical University of Graz, A-8010 Graz, Austria
| | - Janja Marc
- Chair of Clinical Biochemistry, Faculty of Pharmacy, University of Ljubljana, SI-1000 Ljubljana, Slovenia
| | - Miha Sok
- Department of Thoracic Surgery, University Medical Centre Ljubljana, SI-1000 Ljubljana, Slovenia
| | - Darko Cerne
- Chair of Clinical Biochemistry, Faculty of Pharmacy, University of Ljubljana, SI-1000 Ljubljana, Slovenia
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Lipid synthesis in protozoan parasites: a comparison between kinetoplastids and apicomplexans. Prog Lipid Res 2013; 52:488-512. [PMID: 23827884 DOI: 10.1016/j.plipres.2013.06.003] [Citation(s) in RCA: 103] [Impact Index Per Article: 9.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/28/2013] [Revised: 06/16/2013] [Accepted: 06/17/2013] [Indexed: 12/22/2022]
Abstract
Lipid metabolism is of crucial importance for pathogens. Lipids serve as cellular building blocks, signalling molecules, energy stores, posttranslational modifiers, and pathogenesis factors. Parasites rely on a complex system of uptake and synthesis mechanisms to satisfy their lipid needs. The parameters of this system change dramatically as the parasite transits through the various stages of its life cycle. Here we discuss the tremendous recent advances that have been made in the understanding of the synthesis and uptake pathways for fatty acids and phospholipids in apicomplexan and kinetoplastid parasites, including Plasmodium, Toxoplasma, Cryptosporidium, Trypanosoma and Leishmania. Lipid synthesis differs in significant ways between parasites from both phyla and the human host. Parasites have acquired novel pathways through endosymbiosis, as in the case of the apicoplast, have dramatically reshaped substrate and product profiles, and have evolved specialized lipids to interact with or manipulate the host. These differences potentially provide opportunities for drug development. We outline the lipid pathways for key species in detail as they progress through the developmental cycle and highlight those that are of particular importance to the biology of the pathogens and/or are the most promising targets for parasite-specific treatment.
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Regulation of Phosphatidylethanolamine Homeostasis—The Critical Role of CTP:Phosphoethanolamine Cytidylyltransferase (Pcyt2). Int J Mol Sci 2013; 14:2529-50. [PMID: 23354482 PMCID: PMC3588000 DOI: 10.3390/ijms14022529] [Citation(s) in RCA: 55] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2012] [Revised: 01/02/2013] [Accepted: 01/17/2013] [Indexed: 12/21/2022] Open
Abstract
Phosphatidylethanolamine (PE) is the most abundant lipid on the protoplasmatic leaflet of cellular membranes. It has a pivotal role in cellular processes such as membrane fusion, cell cycle regulation, autophagy, and apoptosis. CTP:phosphoethanolamine cytidylyltransferase (Pcyt2) is the main regulatory enzyme in de novo biosynthesis of PE from ethanolamine and diacylglycerol by the CDP-ethanolamine Kennedy pathway. The following is a summary of the current state of knowledge on Pcyt2 and how splicing and isoform specific differences could lead to variations in functional properties in this family of enzymes. Results from the most recent studies on Pcyt2 transcriptional regulation, promoter function, autophagy, and cell growth regulation are highlighted. Recent data obtained from Pcyt2 knockout mouse models is also presented, demonstrating the essentiality of this gene in embryonic development as well as the major physiological consequences of deletion of one Pcyt2 allele. Those include development of symptoms of the metabolic syndrome such as elevated lipogenesis and lipoprotein secretion, hypertriglyceridemia, liver steatosis, obesity, and insulin resistance. The objective of this review is to elucidate the nature of Pcyt2 regulation by linking its catalytic function with the regulation of lipid and energy homeostasis.
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Ríos-Marco P, Jiménez-López JM, Marco C, Segovia JL, Carrasco MP. Antitumoral Alkylphospholipids Induce Cholesterol Efflux from the Plasma Membrane in HepG2 Cells. J Pharmacol Exp Ther 2010; 336:866-73. [DOI: 10.1124/jpet.110.172890] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023] Open
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Disruption of cellular cholesterol transport and homeostasis as a novel mechanism of action of membrane-targeted alkylphospholipid analogues. Br J Pharmacol 2010; 160:355-66. [PMID: 20423345 DOI: 10.1111/j.1476-5381.2010.00689.x] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022] Open
Abstract
BACKGROUND AND PURPOSE Alkylphospholipid (APL) analogues constitute a new class of synthetic anti-tumour agents that act directly on cell membranes. We have previously demonstrated that hexadecylphosphocholine (HePC) alters intracellular cholesterol traffic and metabolism in HepG2 cells. We now extended our studies to analyse the effects of other clinically relevant APLs, such as edelfosine, erucylphosphocholine and perifosine on intracellular cholesterol homeostasis. EXPERIMENTAL APPROACH Using radiolabelled substrates we determined the effect of APLs on cholesterol metabolism and cholesterol traffic from the plasma membrane to the endoplasmic reticulum (ER). Protein levels and gene expression of the main proteins involved in cholesterol homeostasis were analysed by Western blot and RT-PCR respectively. Membrane raft and non-raft fractions were isolated from HepG2 cells by a detergent-free method. KEY RESULTS All APLs inhibited the transport of cholesterol from the plasma membrane to the ER, which induced a significant cholesterogenic response in HepG2 cells. This response involved an increased gene expression and higher levels of several proteins related to the biosynthesis and the receptor-mediated uptake of cholesterol. Cell exposure to the APL-representative HePC enhanced the content of cholesterol mainly in the membrane raft fractions, compared with the untreated cells. CONCLUSIONS AND IMPLICATIONS Membrane-targeted APLs exhibited a novel and common mechanism of action, through disruption of cholesterol homeostasis, which in turn affected specific lipid microdomains of cellular membranes.
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Jiménez-López JM, Ríos-Marco P, Marco C, Segovia JL, Carrasco MP. Alterations in the homeostasis of phospholipids and cholesterol by antitumor alkylphospholipids. Lipids Health Dis 2010; 9:33. [PMID: 20338039 PMCID: PMC2859738 DOI: 10.1186/1476-511x-9-33] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/2010] [Accepted: 03/25/2010] [Indexed: 11/15/2022] Open
Abstract
The alkylphospholipid analog miltefosine (hexadecylphosphocholine) is a membrane-directed antitumoral and antileishmanial drug belonging to the alkylphosphocholines, a group of synthetic antiproliferative agents that are promising candidates in anticancer therapy. A variety of mechanisms have been suggested to explain the actions of these compounds, which can induce apoptosis and/or cell growth arrest. In this review, we focus on recent advances in our understanding of the actions of miltefosine and other alkylphospholipids on the human hepatoma HepG2 cell line, with a special emphasis on lipid metabolism. Results obtained in our laboratory indicate that miltefosine displays cytostatic activity and causes apoptosis in HepG2 cells. Likewise, treatment with miltefosine produces an interference with the biosynthesis of phosphatidylcholine via both CDP-choline and phosphatidylethanolamine methylation. With regard to sphingolipid metabolism, miltefosine hinders the formation of sphingomyelin, which promotes intracellular accumulation of ceramide. We have demonstrated for the first time that treatment with miltefosine strongly impedes the esterification of cholesterol and that this effect is accompanied by a considerable increase in the synthesis of cholesterol, which leads to higher levels of cholesterol in the cells. Indeed, miltefosine early impairs cholesterol transport from the plasma membrane to the endoplasmic reticulum, causing a deregulation of cholesterol homeostasis. Similar to miltefosine, other clinically-relevant synthetic alkylphospholipids such as edelfosine, erucylphosphocholine and perifosine show growth inhibitory effects on HepG2 cells. All the tested alkylphospholipids also inhibit the arrival of plasma-membrane cholesterol to the endoplasmic reticulum, which induces a significant cholesterogenic response in these cells, involving an increased gene expression and higher levels of several proteins related to the pathway of biosynthesis as well as the receptor-mediated uptake of cholesterol. Thus, membrane-targeted alkylphospholipids exhibit a common mechanism of action through disruption of cholesterol homeostasis. The accumulation of cholesterol within the cell and the reduction in phosphatidylcholine and sphingomyelin biosyntheses certainly alter the ratio of choline-bearing phospholipids to cholesterol, which is critical for the integrity and functionality of specific membrane microdomains such as lipid rafts. Alkylphospholipid-induced alterations in lipid homeostasis with probable disturbance of the native membrane structure could well affect signaling processes vital to cell survival and growth.
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Affiliation(s)
- José M Jiménez-López
- Department of Biochemistry and Molecular Biology I, Faculty of Sciences, University of Granada, Av, Fuentenueva s/n, Granada, Spain
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Hexadecylphosphocholine alters nonvesicular cholesterol traffic from the plasma membrane to the endoplasmic reticulum and inhibits the synthesis of sphingomyelin in HepG2 cells. Int J Biochem Cell Biol 2008; 41:1296-303. [PMID: 19084611 DOI: 10.1016/j.biocel.2008.11.004] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/25/2008] [Revised: 11/11/2008] [Accepted: 11/11/2008] [Indexed: 01/05/2023]
Abstract
The synthetic lipid analogue, hexadecylphosphocholine is an antitumoral and antileishmanial agent that acts on cell membranes and can induce apoptosis. We have previously investigated the effect of hexadecylphosphocholine on the biosynthesis and intracellular transport of cholesterol in the human hepatoma HepG2 cell line. Here we show that the traffic of endocytosed-cholesterol from LDL to the plasma membrane and the transport of newly synthesized cholesterol from the endoplasmic reticulum to the plasma membrane were unaffected by alkylphosphocholine exposure. On the contrary, cholesterol traffic from the plasma membrane to the endoplasmic reticulum was drastically interrupted after 1 h of cell exposition to HePC and, consequently, the intracellular esterification of cholesterol was substantially decreased. Our results also demonstrate that this alkylphosphocholine exclusively affected the nonvesicular, energy-independent cholesterol traffic, without altering the vesicular transport. In addition, hydrolysis of plasma membrane sphingomyelin by exogenously added sphingomyelinase resulted in enhanced plasma-membrane cholesterol esterification, but sphingomyelinase treatment did not prevent the inhibition in cholesteryl ester formation caused by hexadecylphosphocholine. We also found that sphingomyelin synthesis was significantly inhibited in HepG2 cells after exposure to hexadecylphosphocholine. Since sphingomyelin and cholesterol are major lipid constituents of membrane raft microdomains, these results suggest that hexadecylphosphocholine could disturb membrane raft integrity and thence its functionality.
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Carrasco MP, Jiménez-López JM, Segovia JL, Marco C. Hexadecylphosphocholine interferes with the intracellular transport of cholesterol in HepG2 cells. FEBS J 2008; 275:1675-86. [DOI: 10.1111/j.1742-4658.2008.06322.x] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
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Rakotomanga M, Blanc S, Gaudin K, Chaminade P, Loiseau PM. Miltefosine affects lipid metabolism in Leishmania donovani promastigotes. Antimicrob Agents Chemother 2007; 51:1425-30. [PMID: 17242145 PMCID: PMC1855451 DOI: 10.1128/aac.01123-06] [Citation(s) in RCA: 114] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Miltefosine (hexadecylphosphocholine [HePC]) is the first orally active antileishmanial drug. Transient HePC treatment of Leishmania donovani promastigotes at 10 microM significantly reduced the phosphatidylcholine content and enhanced the phosphatidylethanolamine (PE) content in parasite membranes, suggesting a partial inactivation of PE-N-methyltransferase. Phospholipase D activity did not seem to be affected by HePC. In addition, the enhancement of the lysophosphatidylcholine content could be ascribed to phospholipase A2 activation. Moreover, transient HePC treatment had no effect on the fatty acid alkyl chain length or the fatty acid unsaturation rate. Concerning sterols, we found a strong reduction of the C24 alkylated sterol content, and the enhancement of the cholesterol content could be the result of the HePC condensation effect with sterols. Because some of the effects observed after transient HePC treatment were different from those previously observed in HePC-resistant parasites, it could be hypothesized that continuous in vitro drug pressure induces the mechanisms of regulation in Leishmania lipid metabolism.
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Affiliation(s)
- M Rakotomanga
- Chimiothérapie Antiparasitaire, UMR 8076 CNRS, Faculté de Pharmacie, Université Paris-Sud XI, F-92290 Châtenay-Malabry, France
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14
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Jiménez-López JM, Carrasco MP, Marco C, Segovia JL. Hexadecylphosphocholine disrupts cholesterol homeostasis and induces the accumulation of free cholesterol in HepG2 tumour cells. Biochem Pharmacol 2006; 71:1114-21. [PMID: 16466701 DOI: 10.1016/j.bcp.2005.08.001] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/29/2005] [Revised: 07/22/2005] [Accepted: 08/03/2005] [Indexed: 11/19/2022]
Abstract
Hexadecylphosphocholine (HePC) is a synthetic lipid belonging to the alkylphosphocholines (APC), a new group of antiproliferative agents that are proving to be promising candidates in anticancer therapy. We reported in a previous study that HePC interferes with phosphatidylcholine (PC) synthesis in HepG2 cells via both CDP-choline and phosphatidylethanolamine (PE) methylation. We have subsequently extended our studies to show that HePC interferes with sphingolipid metabolism by hindering the formation of sphingomyelin (SM), an effect accompanied by a substantial increase in the incorporation of the exogenous lipogenic precursors into ceramides. Interestingly, we demonstrate for the first time that HePC strongly inhibits the esterification of free cholesterol (FC) by acting at the level of acyl CoA:cholesterol acyltransferase (ACAT) (EC 2.3.1.26) activity. This effect is accompanied by a considerable increase in the synthesis of cholesterol, which leads to a rise in the levels of FC in cells. We are left in no doubt that the imbalance in the metabolism of membrane-lipid components vital to cell survival may well be responsible for the observed DNA fragmentation and activation of caspase-3, an enzyme involved in the cell apoptosis found in this study.
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Affiliation(s)
- José M Jiménez-López
- Department of Biochemistry and Molecular Biology, Faculty of Sciences, University of Granada, Spain
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Shorten PR, Upreti GC. A mathematical model of fatty acid metabolism and VLDL assembly in human liver. Biochim Biophys Acta Mol Cell Biol Lipids 2005; 1736:94-108. [PMID: 16137923 DOI: 10.1016/j.bbalip.2005.07.007] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/20/2004] [Revised: 07/22/2005] [Accepted: 07/28/2005] [Indexed: 11/17/2022]
Abstract
The lipid composition of very-low-density lipoprotein (VLDL) in plasma is crucial for human health. A pre-requisite for the alteration of VLDL composition is a co-ordinated understanding of the complex interactions in VLDL assembly. In order to determine the potential effects of changes in substrate availability on VLDL lipid composition, we constructed, parameterized and evaluated a mechanistic mathematical model of the biosynthesis of triglycerides, phospholipids, and cholesterol esters and the assembly of VLDL in human hepatocytes. Using published data on human liver metabolism, the model was also used to provide insight into the complex process of lipid metabolism and to estimate the affinities of different liver enzymes for different fatty acids (FA). For example, we found that Delta6-desaturase is 19 times more selective for C18:3n-3 than C18:2n-6, stearoyl-CoA-desaturase is 2.7 times more selective for C18:0 than C16:0, Delta5-desaturase desaturates C20:4n-3 preferentially over C20:3n-6 and FA elongase preferentially elongates C18:3n-6. The model was also used to predict the plasma free fatty acid (FFA) composition required to generate a prescribed change in plasma lipoprotein FA composition. Furthermore, the model was tested against a published human feeding trial that investigated the effect of changes in dietary FA composition on human plasma lipid FA composition. The model is a useful tool for predicting the effect of changes in plasma FFA composition on plasma lipoprotein lipid FA composition.
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Affiliation(s)
- P R Shorten
- AgResearch, Ruakura Research Centre, Private Bag 3123, Hamilton, New Zealand.
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