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Milavec M, Pavšič J, Bogožalec Košir A, Jones GM, O'Sullivan DM, Devonshire AS, Van Heuverswyn F, Karczmarczyk M, Neeb J, Plauth A, Corbisier P, Schimmel H, Kummrow A, Neukammer J, Foy CA, Kammel M, Grunert HP, Zeichhardt H, Huggett JF. The performance of human cytomegalovirus digital PCR reference measurement procedure in seven external quality assessment schemes over four years. Methods 2021; 201:65-73. [PMID: 33812016 DOI: 10.1016/j.ymeth.2021.03.016] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/28/2021] [Revised: 03/18/2021] [Accepted: 03/22/2021] [Indexed: 11/16/2022] Open
Abstract
A candidate digital PCR (dPCR)-based reference measurement procedure for quantification of human cytomegalovirus (hCMV) was evaluated in 10 viral load comparison schemes (seven external quality assessment (EQA) and three additional training schemes) organized by INSTAND e.V. over four years (between September 2014 and March 2018). Four metrology institutes participated in these schemes using the same extraction method and dPCR measurement procedure for the hCMV specific target sequence of UL54 gene. The calibration independent reference measurement procedure results from the metrology institutes were compared to the results of the clinical diagnostic laboratories applying hCMV qPCR measurement procedures calibrated to reference materials. While the criteria for the acceptable deviation from the target value interval for INSTAND's EQA schemes is from -0.8 log10 to +0.8 log10, the majority of dPCR results were between -0.2 log10 to +0.2 log10. Only 4 out of 45 results exceeded this interval with the maximum deviation of -0.542 log10. In the training schemes containing samples with lower hCMV concentrations, more than half of the results deviated less than ±0.2 log10 from the target value, while more than 95% deviated less than ±0.4 log10 from the target value. Evaluation of intra- and inter-laboratory variation of dPCR results confirmed high reproducibility and trueness of the method. This work demonstrates that dPCR has the potential to act as a calibration independent reference measurement procedure for the value assignment of hCMV calibration and reference materials to support qPCR calibration as well as ultimately for routine hCMV load testing.
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Affiliation(s)
- Mojca Milavec
- Department of Biotechnology and Systems Biology, National Institute of Biology, Večna pot 111, 1000 Ljubljana, Slovenia.
| | - Jernej Pavšič
- Department of Biotechnology and Systems Biology, National Institute of Biology, Večna pot 111, 1000 Ljubljana, Slovenia
| | - Alexandra Bogožalec Košir
- Department of Biotechnology and Systems Biology, National Institute of Biology, Večna pot 111, 1000 Ljubljana, Slovenia
| | - Gerwyn M Jones
- National Measurement Laboratory (NML), LGC, Queens Road, Teddington, Middlesex TW11 0LY, United Kingdom
| | - Denise M O'Sullivan
- National Measurement Laboratory (NML), LGC, Queens Road, Teddington, Middlesex TW11 0LY, United Kingdom
| | - Alison S Devonshire
- National Measurement Laboratory (NML), LGC, Queens Road, Teddington, Middlesex TW11 0LY, United Kingdom
| | | | | | - Jannika Neeb
- Physikalisch Technische Bundesanstalt, Abbestr. 2-12, D-10587 Berlin, Germany
| | - Annabell Plauth
- Physikalisch Technische Bundesanstalt, Abbestr. 2-12, D-10587 Berlin, Germany
| | | | - Heinz Schimmel
- European Commission, Joint Research Centre (JRC), Geel, Belgium
| | - Andreas Kummrow
- Physikalisch Technische Bundesanstalt, Abbestr. 2-12, D-10587 Berlin, Germany
| | - Jörg Neukammer
- Physikalisch Technische Bundesanstalt, Abbestr. 2-12, D-10587 Berlin, Germany
| | - Carole A Foy
- National Measurement Laboratory (NML), LGC, Queens Road, Teddington, Middlesex TW11 0LY, United Kingdom
| | - Martin Kammel
- INSTAND, Gesellschaft zur Foerderung der Qualitaetssicherung in medizinischen Laboratorien e.V., Ubierstr.20, D-40223 Düsseldorf, Germany; IQVD GmbH, Institut fuer Qualitaetssicherung in der Virusdiagnostik, Potsdamer Chaussee 80, D-14129 Berlin, Germany
| | - Hans-Peter Grunert
- GBD Gesellschaft fuer Biotechnologische Diagnostik mbH, Berlin, Potsdamer Chaussee 80, D-14129 Berlin, Germany
| | - Heinz Zeichhardt
- INSTAND, Gesellschaft zur Foerderung der Qualitaetssicherung in medizinischen Laboratorien e.V., Ubierstr.20, D-40223 Düsseldorf, Germany; IQVD GmbH, Institut fuer Qualitaetssicherung in der Virusdiagnostik, Potsdamer Chaussee 80, D-14129 Berlin, Germany; GBD Gesellschaft fuer Biotechnologische Diagnostik mbH, Berlin, Potsdamer Chaussee 80, D-14129 Berlin, Germany
| | - Jim F Huggett
- National Measurement Laboratory (NML), LGC, Queens Road, Teddington, Middlesex TW11 0LY, United Kingdom; School of Biosciences & Medicine, Faculty of Health & Medical Science, University of Surrey, Guildford, United Kingdom
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Falak S, Macdonald R, Busby EJ, O'Sullivan DM, Milavec M, Plauth A, Kammel M, Zeichhardt H, Grunert HP, Kummrow A, Huggett JF. An assessment of the reproducibility of reverse transcription digital PCR quantification of HIV-1. Methods 2021; 201:34-40. [PMID: 33722693 DOI: 10.1016/j.ymeth.2021.03.006] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/23/2020] [Revised: 02/28/2021] [Accepted: 03/08/2021] [Indexed: 11/30/2022] Open
Abstract
Viral load monitoring in human immunodeficiency virus type 1 (HIV-1) infection is often performed using reverse transcription quantitative PCR (RT-qPCR) to observe response to treatment and identify the development of resistance. Traceability is achieved using a calibration hierarchy traceable to the International Unit (IU). IU values are determined using consensus agreement derived from estimations by different laboratories. Such a consensus approach is necessary due to the fact that there are currently no reference measurement procedures available that can independently assign a reference value to viral reference materials for molecular in vitro diagnostic tests. Digital PCR (dPCR) is a technique that has the potential to be used for this purpose. In this paper, we investigate the ability of reverse transcriptase dPCR (RT-dPCR) to quantify HIV-1 genomic RNA without calibration. Criteria investigated included the performance of HIV-1 RNA extraction steps, choice of reverse transcription approach and selection of target gene with assays performed in both single and duplex format. We developed a protocol which was subsequently applied by two independent laboratories as part of an external quality assurance (EQA) scheme for HIV-1 genome detection. Our findings suggest that RT-dPCR could be used as reference measurement procedure to aid the value assignment of HIV-1 reference materials to support routine calibration of HIV-1 viral load testing by RT-qPCR.
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Affiliation(s)
- Samreen Falak
- Physikalisch Technische Bundesanstalt, Abbestr. 2-12, 10587 Berlin, Germany.
| | - Rainer Macdonald
- Physikalisch Technische Bundesanstalt, Abbestr. 2-12, 10587 Berlin, Germany
| | - Eloise J Busby
- National Measurement Laboratory, LGC, Queens Road, Teddington, Middlesex TW11 0LY, United Kingdom
| | - Denise M O'Sullivan
- National Measurement Laboratory, LGC, Queens Road, Teddington, Middlesex TW11 0LY, United Kingdom
| | - Mojca Milavec
- Department of Biotechnology and Systems Biology, National Institute of Biology, Ljubljana, Slovenia
| | - Annabell Plauth
- Physikalisch Technische Bundesanstalt, Abbestr. 2-12, 10587 Berlin, Germany
| | - Martin Kammel
- INSTAND, Gesellschaft zur Foerderung der Qualitaetssicherung in medizinischen Laboratorien e.V., Ubierstr.20, D-40223 Düsseldorf, Germany; IQVD GmbH, Institut fuer Qualitaetssicherung in der Virusdiagnostik, Potsdamer Chaussee 80, 14129 Berlin, Germany
| | - Heinz Zeichhardt
- INSTAND, Gesellschaft zur Foerderung der Qualitaetssicherung in medizinischen Laboratorien e.V., Ubierstr.20, D-40223 Düsseldorf, Germany; IQVD GmbH, Institut fuer Qualitaetssicherung in der Virusdiagnostik, Potsdamer Chaussee 80, 14129 Berlin, Germany
| | - Hans-Peter Grunert
- GBD Gesellschaft fuer Biotechnologische Diagnostik mbH, Berlin, Potsdamer Chaussee 80, 14129 Berlin, Germany
| | - Andreas Kummrow
- Physikalisch Technische Bundesanstalt, Abbestr. 2-12, 10587 Berlin, Germany
| | - Jim F Huggett
- National Measurement Laboratory, LGC, Queens Road, Teddington, Middlesex TW11 0LY, United Kingdom; School of Biosciences & Medicine, Faculty of Health & Medical Science, University of Surrey, Guildford GU2 7XH, United Kingdom.
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Plauth A, Geikowski A, Cichon S, Wowro SJ, Liedgens L, Rousseau M, Weidner C, Fuhr L, Kliem M, Jenkins G, Lotito S, Wainwright LJ, Sauer S. Hormetic shifting of redox environment by pro-oxidative resveratrol protects cells against stress. Free Radic Biol Med 2016; 99:608-622. [PMID: 27515816 DOI: 10.1016/j.freeradbiomed.2016.08.006] [Citation(s) in RCA: 62] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/07/2016] [Revised: 08/04/2016] [Accepted: 08/07/2016] [Indexed: 11/22/2022]
Abstract
Resveratrol has gained tremendous interest owing to multiple reported health-beneficial effects. However, the underlying key mechanism of action of this natural product remained largely controversial. Here, we demonstrate that under physiologically relevant conditions major biological effects of resveratrol can be attributed to its generation of oxidation products such as reactive oxygen species (ROS). At low nontoxic concentrations (in general <50µM), treatment with resveratrol increased viability in a set of representative cell models, whereas application of quenchers of ROS completely truncated these beneficial effects. Notably, resveratrol treatment led to mild, Nrf2-specific gene expression reprogramming. For example, in primary epidermal keratinocytes derived from human skin this coordinated process resulted in a 1.3-fold increase of endogenously generated glutathione (GSH) and subsequently in a quantitative reduction of the cellular redox environment by 2.61mVmmol GSH per g protein. After induction of oxidative stress by using 0.78% (v/v) ethanol, endogenous generation of ROS was consequently reduced by 24% in resveratrol pre-treated cells. In contrast to the common perception that resveratrol acts mainly as a chemical antioxidant or as a target protein-specific ligand, we propose that the cellular response to resveratrol treatment is essentially based on oxidative triggering. In physiological microenvironments this molecular training can lead to hormetic shifting of cellular defense towards a more reductive state to improve physiological resilience to oxidative stress.
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Affiliation(s)
- Annabell Plauth
- Otto Warburg Laboratory, Max Planck Institute for Molecular Genetics, 14195 Berlin, Germany
| | - Anne Geikowski
- Otto Warburg Laboratory, Max Planck Institute for Molecular Genetics, 14195 Berlin, Germany
| | - Susanne Cichon
- Otto Warburg Laboratory, Max Planck Institute for Molecular Genetics, 14195 Berlin, Germany
| | - Sylvia J Wowro
- Otto Warburg Laboratory, Max Planck Institute for Molecular Genetics, 14195 Berlin, Germany
| | - Linda Liedgens
- Otto Warburg Laboratory, Max Planck Institute for Molecular Genetics, 14195 Berlin, Germany
| | - Morten Rousseau
- Otto Warburg Laboratory, Max Planck Institute for Molecular Genetics, 14195 Berlin, Germany
| | - Christopher Weidner
- Otto Warburg Laboratory, Max Planck Institute for Molecular Genetics, 14195 Berlin, Germany
| | - Luise Fuhr
- Otto Warburg Laboratory, Max Planck Institute for Molecular Genetics, 14195 Berlin, Germany
| | - Magdalena Kliem
- Otto Warburg Laboratory, Max Planck Institute for Molecular Genetics, 14195 Berlin, Germany
| | - Gail Jenkins
- Unilever R&D, Colworth Science Park, Sharnbrook, Bedfordshire MK44 1LQ, UK
| | - Silvina Lotito
- Unilever R&D, Colworth Science Park, Sharnbrook, Bedfordshire MK44 1LQ, UK
| | - Linda J Wainwright
- Unilever R&D, Colworth Science Park, Sharnbrook, Bedfordshire MK44 1LQ, UK
| | - Sascha Sauer
- Otto Warburg Laboratory, Max Planck Institute for Molecular Genetics, 14195 Berlin, Germany; CU Systems Medicine, University of Würzburg, Josef-Schneider-Straße 2, Building D15, 97080 Würzburg, Germany; Laboratory of Functional Genomics, Nutrigenomics and Systems Biology, BIMSB and BIH Genomics Platforms, Max-Delbrück-Center for Molecular Medicine, Robert-Rössle-Straße 10, 13125 Berlin, Germany.
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Plauth A, Geikowski A, Cichon S, Wowro SJ, Liedgens L, Rousseau M, Weidner C, Fuhr L, Kliem M, Jenkins G, Lotito S, Wainwright LJ, Sauer S. Data of oxygen- and pH-dependent oxidation of resveratrol. Data Brief 2016; 9:433-437. [PMID: 27699197 PMCID: PMC5037118 DOI: 10.1016/j.dib.2016.09.012] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/10/2016] [Revised: 08/31/2016] [Accepted: 09/09/2016] [Indexed: 11/25/2022] Open
Abstract
We show here if under physiologically relevant conditions resveratrol (RSV) remains stable or not. We further show under which circumstances various oxidation products of RSV such as ROS can be produced. For example, in addition to the widely known effect of bicarbonate ions, high pH values promote the decay of RSV. Moreover, we analyse the impact of reduction of the oxygen partial pressure on the pH-dependent oxidation of RSV. For further interpretation and discussion of these focused data in a broader context we refer to the article “Hormetic shifting of redox environment by pro-oxidative resveratrol protects cells against stress” (Plauth et al., in press) [1].
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Affiliation(s)
- Annabell Plauth
- Otto Warburg Laboratory, Max Planck Institute for Molecular Genetics, 14195 Berlin, Germany
| | - Anne Geikowski
- Unilever R&D, Colworth Science Park, Sharnbrook, Bedfordshire MK44 1LQ, UK
| | - Susanne Cichon
- Otto Warburg Laboratory, Max Planck Institute for Molecular Genetics, 14195 Berlin, Germany
| | - Sylvia J Wowro
- Otto Warburg Laboratory, Max Planck Institute for Molecular Genetics, 14195 Berlin, Germany
| | - Linda Liedgens
- Otto Warburg Laboratory, Max Planck Institute for Molecular Genetics, 14195 Berlin, Germany
| | - Morten Rousseau
- Otto Warburg Laboratory, Max Planck Institute for Molecular Genetics, 14195 Berlin, Germany
| | - Christopher Weidner
- Otto Warburg Laboratory, Max Planck Institute for Molecular Genetics, 14195 Berlin, Germany
| | - Luise Fuhr
- Otto Warburg Laboratory, Max Planck Institute for Molecular Genetics, 14195 Berlin, Germany
| | - Magdalena Kliem
- Otto Warburg Laboratory, Max Planck Institute for Molecular Genetics, 14195 Berlin, Germany
| | - Gail Jenkins
- Unilever R&D, Colworth Science Park, Sharnbrook, Bedfordshire MK44 1LQ, UK
| | - Silvina Lotito
- Unilever R&D, Colworth Science Park, Sharnbrook, Bedfordshire MK44 1LQ, UK
| | - Linda J Wainwright
- Unilever R&D, Colworth Science Park, Sharnbrook, Bedfordshire MK44 1LQ, UK
| | - Sascha Sauer
- Otto Warburg Laboratory, Max Planck Institute for Molecular Genetics, 14195 Berlin, Germany; University of Würzburg, CU Systems Medicine, Josef-Schneider-Straße 2, Building D15, 97080 Würzburg, Germany; Laboratory of Functional Genomics, Nutrigenomics and Systems Biology, BIMSB and BIH Genomics Platforms, Max-Delbrück-Center for Molecular Medicine, Robert-Rössle-Straße 10, 13125 Berlin, Germany
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Weidner C, Rousseau M, Micikas RJ, Fischer C, Plauth A, Wowro SJ, Siems K, Hetterling G, Kliem M, Schroeder FC, Sauer S. Amorfrutin C Induces Apoptosis and Inhibits Proliferation in Colon Cancer Cells through Targeting Mitochondria. J Nat Prod 2016; 79:2-12. [PMID: 26731300 DOI: 10.1021/acs.jnatprod.5b00072] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/05/2023]
Abstract
A known (1) and a structurally related new natural product (2), both belonging to the amorfrutin benzoic acid class, were isolated from the roots of Glycyrrhiza foetida. Compound 1 (amorfrutin B) is an efficient agonist of the nuclear peroxisome proliferator activated receptor (PPAR) gamma and of other PPAR subtypes. Compound 2 (amorfrutin C) showed comparably lower PPAR activation potential. Amorfrutin C exhibited striking antiproliferative effects for human colorectal cancer cells (HT-29 and T84), prostate cancer (PC-3), and breast cancer (MCF7) cells (IC50 values ranging from 8 to 16 μM in these cancer cell lines). Notably, amorfrutin C (2) showed less potent antiproliferative effects in primary colon cells. For HT-29 cells, compound 2 induced G0/G1 cell cycle arrest and modulated protein expression of key cell cycle modulators. Amorfrutin C further induced apoptotic events in HT-29 cells, including caspase activation, DNA fragmentation, PARP cleavage, phosphatidylserine externalization, and formation of reactive oxygen species. Mechanistic studies revealed that 2 disrupts the mitochondrial integrity by depolarization of the mitochondrial membrane (IC50 0.6 μM) and permanent opening of the mitochondrial permeability transition pore, leading to increased mitochondrial oxygen consumption and extracellular acidification. Structure-activity-relationship experiments revealed the carboxylic acid and the hydroxy group residues of 2 as fundamental structural requirements for inducing these apoptotic effects. Synergy analyses demonstrated stimulation of the death receptor signaling pathway. Taken together, amorfrutin C (2) represents a promising lead for the development of anticancer drugs.
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Affiliation(s)
- Christopher Weidner
- Otto Warburg Laboratory, Max Planck Institute for Molecular Genetics , D-14195 Berlin, Germany
| | - Morten Rousseau
- Otto Warburg Laboratory, Max Planck Institute for Molecular Genetics , D-14195 Berlin, Germany
| | - Robert J Micikas
- Boyce Thompson Institute and Department of Chemistry and Chemical Biology, Cornell University , Ithaca, New York 14853, United States
| | - Cornelius Fischer
- Otto Warburg Laboratory, Max Planck Institute for Molecular Genetics , D-14195 Berlin, Germany
| | - Annabell Plauth
- Otto Warburg Laboratory, Max Planck Institute for Molecular Genetics , D-14195 Berlin, Germany
| | - Sylvia J Wowro
- Otto Warburg Laboratory, Max Planck Institute for Molecular Genetics , D-14195 Berlin, Germany
| | - Karsten Siems
- AnalytiCon Discovery GmbH , D-14473 Potsdam, Germany
| | | | - Magdalena Kliem
- Otto Warburg Laboratory, Max Planck Institute for Molecular Genetics , D-14195 Berlin, Germany
| | - Frank C Schroeder
- Boyce Thompson Institute and Department of Chemistry and Chemical Biology, Cornell University , Ithaca, New York 14853, United States
| | - Sascha Sauer
- Otto Warburg Laboratory, Max Planck Institute for Molecular Genetics , D-14195 Berlin, Germany
- CU Systems Medicine, University of Würzburg , D-97080 Würzburg, Germany
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Fuhr L, Rousseau M, Plauth A, Schroeder FC, Sauer S. Amorfrutins Are Natural PPARγ Agonists with Potent Anti-inflammatory Properties. J Nat Prod 2015; 78:1160-1164. [PMID: 25938459 DOI: 10.1021/np500747y] [Citation(s) in RCA: 42] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
Amorfrutins are isoprenoid-substituted benzoic acid derivatives, which were found in Amorpha fruticosa L. (bastard indigo) and in Glycyrrhiza foetida Desf. (licorice). Recently, amorfrutins were shown to be selective activators of the nuclear receptor PPARγ. Here, we investigated the effects and PPARγ-based mechanisms of reducing inflammation in colon cells by treatment with amorfrutins. In TNF-α-stimulated colon cells amorfrutin A (1) reduced significantly the expression and secretion of several inflammation mediators, in part due to interaction with PPARγ. These results support the hypothesis that amorfrutins may have the potential to treat inflammation disorders such as chronic inflammatory bowel diseases.
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Affiliation(s)
- Luise Fuhr
- †Otto Warburg Laboratory, Max Planck Institute for Molecular Genetics, Ihnestrasse 63-73, 14195 Berlin, Germany
| | - Morten Rousseau
- †Otto Warburg Laboratory, Max Planck Institute for Molecular Genetics, Ihnestrasse 63-73, 14195 Berlin, Germany
| | - Annabell Plauth
- †Otto Warburg Laboratory, Max Planck Institute for Molecular Genetics, Ihnestrasse 63-73, 14195 Berlin, Germany
| | - Frank C Schroeder
- ‡Boyce Thompson Institute and Department of Chemistry and Chemical Biology, Cornell University, Ithaca, New York 14853, United States
| | - Sascha Sauer
- †Otto Warburg Laboratory, Max Planck Institute for Molecular Genetics, Ihnestrasse 63-73, 14195 Berlin, Germany
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Weidner C, Rousseau M, Plauth A, Wowro SJ, Fischer C, Abdel-Aziz H, Sauer S. Melissa officinalis extract induces apoptosis and inhibits proliferation in colon cancer cells through formation of reactive oxygen species. Phytomedicine 2015; 22:262-70. [PMID: 25765831 DOI: 10.1016/j.phymed.2014.12.008] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/25/2014] [Revised: 12/15/2014] [Accepted: 12/15/2014] [Indexed: 05/02/2023]
Abstract
PURPOSE Efficient strategies for the prevention of colon cancer are extensively being explored, including dietary intervention and the development of novel phytopharmaceuticals. Safe extracts of edible plants contain structurally diverse molecules that can effectively interfere with multi-factorial diseases such as colon cancer. In this study, we describe the antiproliferative and proapoptotic effects of ethanolic lemon balm (Melissa officinalis) leaves extract in human colon carcinoma cells. We further investigated the role of extra- and intracellular reactive oxygen species (ROS). METHODS Antitumor effects of lemon balm extract (LBE) were investigated in HT-29 and T84 human colon carcinoma cells. Inhibition of proliferation was analyzed by DNA quantification. The causal cell cycle arrest was determined by flow cytometry of propidium iodide-stained cells and by immunoblotting of cell cycle regulator proteins. To investigate apoptosis, cleavage of caspases 3 and 7 was detected by immunoblotting and fluorescence microscopy. Phosphatidylserine externalization was measured by Annexin V assays. Mechanistic insights were gained by measurement of ROS using the indicator dyes CM-H2DCFDA and Cell ROX Green. RESULTS After 3 and 4 days of treatment, LBE inhibited the proliferation of HT-29 and T84 colon carcinoma cells with an inhibitory concentration (IC50) of 346 and 120 µg/ml, respectively. Antiproliferative effects were associated with a G2/M cell cycle arrest and reduced protein expression of cyclin dependent kinases (CDK) 2, 4, 6, cyclin D3, and induced expression of cyclin-dependent kinase inhibitor 2C (p18) and 1A (p21). LBE (600 µg/ml) induced cleavage of caspases 3 and 7 and phosphatidylserine externalization. LBE-induced apoptosis was further associated with formation of ROS, whereas quenching of ROS by antioxidants completely rescued the colon carcinoma cells from LBE-induced apoptosis. CONCLUSIONS Lemon balm (Melissa officinalis) extract inhibits the proliferation of colon carcinoma cells and induces apoptosis through formation of ROS. Taken together, LBE or subfractions thereof could be used for the prevention of colon cancer.
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Affiliation(s)
- C Weidner
- Otto Warburg Laboratory, Max Planck Institute for Molecular Genetics, 14195 Berlin, Germany
| | - M Rousseau
- Otto Warburg Laboratory, Max Planck Institute for Molecular Genetics, 14195 Berlin, Germany
| | - A Plauth
- Otto Warburg Laboratory, Max Planck Institute for Molecular Genetics, 14195 Berlin, Germany
| | - S J Wowro
- Otto Warburg Laboratory, Max Planck Institute for Molecular Genetics, 14195 Berlin, Germany
| | - C Fischer
- Otto Warburg Laboratory, Max Planck Institute for Molecular Genetics, 14195 Berlin, Germany
| | - H Abdel-Aziz
- Scientific Department, Steigerwald Arzneimittelwerk GmbH, 64295 Darmstadt, Germany
| | - S Sauer
- Otto Warburg Laboratory, Max Planck Institute for Molecular Genetics, 14195 Berlin, Germany.
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