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El Ouardi M, Tamarit L, Vayá I, Miranda MA, Andreu I. Cellular photo(geno)toxicity of gefitinib after biotransformation. Front Pharmacol 2023; 14:1208075. [PMID: 37351506 PMCID: PMC10283009 DOI: 10.3389/fphar.2023.1208075] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/18/2023] [Accepted: 05/23/2023] [Indexed: 06/24/2023] Open
Abstract
Gefitinib (GFT) is a selective epidermal growth factor receptor (EGFR) inhibitor clinically used for the treatment of patients with non-small cell lung cancer. Bioactivation by mainly Phase I hepatic metabolism leads to chemically reactive metabolites such as O-Demethyl gefitinib (DMT-GFT), 4-Defluoro-4-hydroxy gefitinib (DF-GFT), and O-Demorpholinopropyl gefitinib (DMOR-GFT), which display an enhanced UV-light absorption. In this context, the aim of the present study is to investigate the capability of gefitinib metabolites to induce photosensitivity disorders and to elucidate the involved mechanisms. According to the neutral red uptake (NRU) phototoxicity test, only DF-GFT metabolite can be considered non-phototoxic to cells with a photoirritation factor (PIF) close to 1. Moreover, DMOR-GFT is markedly more phototoxic than the parent drug (PIF = 48), whereas DMT-GFT is much less phototoxic (PIF = 7). Using the thiobarbituric acid reactive substances (TBARS) method as an indicator of lipid photoperoxidation, only DMOR-GFT has demonstrated the ability to photosensitize this process, resulting in a significant amount of TBARS (similar to ketoprofen, which was used as the positive control). Protein photooxidation monitored by 2,4-dinitrophenylhydrazine (DNPH) derivatization method is mainly mediated by GFT and, to a lesser extent, by DMOR-GFT; in contrast, protein oxidation associated with DMT-GFT is nearly negligible. Interestingly, the damage to cellular DNA as revealed by the comet assay, indicates that DMT-GFT has the highest photogenotoxic potential; moreover, the DNA damage induced by this metabolite is hardly repaired by the cells after a time recovery of 18 h. This could ultimately result in mutagenic and carcinogenic effects. These results could aid oncologists when prescribing TKIs to cancer patients and, thus, establish the conditions of use and recommend photoprotection guidelines.
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Affiliation(s)
- Meryem El Ouardi
- Departamento de Química-Instituto de Tecnología Química UPV-CSIC, Universitat Politècnica de València, Valencia, Spain
- Unidad Mixta de Investigación UPV- IIS La Fe, Hospital Universitari i Politècnic La Fe, Valencia, Spain
| | - Lorena Tamarit
- Departamento de Química-Instituto de Tecnología Química UPV-CSIC, Universitat Politècnica de València, Valencia, Spain
- Unidad Mixta de Investigación UPV- IIS La Fe, Hospital Universitari i Politècnic La Fe, Valencia, Spain
| | - Ignacio Vayá
- Departamento de Química-Instituto de Tecnología Química UPV-CSIC, Universitat Politècnica de València, Valencia, Spain
- Unidad Mixta de Investigación UPV- IIS La Fe, Hospital Universitari i Politècnic La Fe, Valencia, Spain
| | - Miguel A. Miranda
- Departamento de Química-Instituto de Tecnología Química UPV-CSIC, Universitat Politècnica de València, Valencia, Spain
- Unidad Mixta de Investigación UPV- IIS La Fe, Hospital Universitari i Politècnic La Fe, Valencia, Spain
| | - Inmaculada Andreu
- Departamento de Química-Instituto de Tecnología Química UPV-CSIC, Universitat Politècnica de València, Valencia, Spain
- Unidad Mixta de Investigación UPV- IIS La Fe, Hospital Universitari i Politècnic La Fe, Valencia, Spain
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Farghadani R, Seifaddinipour M, Rajarajeswaran J, Abdulla MA, Mohd Hashim NB, Khaing SL, Salehen NB. In vivo acute toxicity evaluation and in vitro molecular mechanism study of antiproliferative activity of a novel indole Schiff base β-diiminato manganese III complex in hormone-dependent and triple negative breast cancer cells. PeerJ 2019; 7:e7686. [PMID: 31608167 PMCID: PMC6786247 DOI: 10.7717/peerj.7686] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/26/2019] [Accepted: 08/19/2019] [Indexed: 12/28/2022] Open
Abstract
Breast cancer is the most frequently diagnosed cancer among women worldwide. Recently, increasing attention has been paid to the anticancer effects of transition metal complexes of indole Schiff bases. β-diiminato ManganeseIII complex has shown promising cell cycle arrest and apoptosis induction against MCF-7 and MDA-MB-231 breast cancer cells. In this study, time- and dose- dependent inhibitory activity were evaluated using MTT assay after 48 h and 72 h exposure time. In addition, median effect analysis was conducted according to Chou-Talalay method to investigate whether MnIII complex has synergistic effect in combination with chemotherapeutic drugs on inhibiting breast cancer cell growth. The molecular mechanisms underlying its potent antiproliferative effect was determined through bioluminescent caspase-3/7, -8 and -9 activity assays and quantitative expression analysis of cell cycle- and apoptosis-related genes. Furthermore, safety evaluation of MnIII complex was assessed through the acute oral toxicity test in in vivo model. The MTT assay results revealed that it potently reduced the viability of MCF-7 (IC50 of 0.63 ± 0.07 µg/mL for 48 h and 0.39 ± 0.08 µg/mL for 72 h) and MDA-MB-231 (1.17 ± 0.06 µg/mL for 48 h, 1.03 ± 0.15 µg/mL for 72 h) cells in dose- and time-dependent manner. Combination treatment also enhanced the cytotoxic effects of doxorubicin but not tamoxifen on inhibiting breast cancer cell growth. The involvement of intrinsic and extrinsic pathway in apoptosis induction was exhibited through the increased activity of caspase-9 and caspase-8, respectively, leading to enhanced downstream executioner caspase-3/7 activity in treated MCF-7 and MDA-MB-231 cells. In addition, gene expression analysis revealed that MnIII complex exerts its antiproliferative effect via up-and down-regulation of p21 and cyclin D1, respectively, along with increased expression of Bax/Bcl-2 ratio, TNF-α, initiator caspase-8 and -10 and effector caspase-3 in MCF-7 and MDA-MB-231 cells. However, the results did not show increased caspase-8 activity in treated MCF-7 cells. Furthermore, in vivo acute oral toxicity test revealed no signs of toxicity and mortality in treated animal models compared to the control group. Collectively, the promising inhibitory effect and molecular and mechanistic evidence of antiproliferative activity of MnIII complex and its safety characterization have demonstrated that it may have therapeutic value in breast cancer treatment worthy of further investigation and development.
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Affiliation(s)
- Reyhaneh Farghadani
- Department of Molecular Medicine, Faculty of Medicine, University of Malaya, Kuala Lumpur, Malaysia
| | - Maryam Seifaddinipour
- Institute of Biological Sciences, Faculty of Science, University of Malaya, Kuala Lumpur, Malaysia
| | - Jayakumar Rajarajeswaran
- Department of Molecular Medicine, Faculty of Medicine, University of Malaya, Kuala Lumpur, Malaysia
| | - Mahmood Ameen Abdulla
- Department of Biomedical Science, Faculty of Medicine, University of Malaya, Kuala Lumpur, Malaysia
| | | | - Si Lay Khaing
- Department of Obstetrics and Gynecology, Faculty of Medicine, University of Malaya, Kuala Lumpur, Malaysia
| | - Nur'ain Binti Salehen
- Department of Biomedical Science, Faculty of Medicine, University of Malaya, Kuala Lumpur, Malaysia
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3
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Matos CP, Adiguzel Z, Yildizhan Y, Cevatemre B, Onder TB, Cevik O, Nunes P, Ferreira LP, Carvalho MD, Campos DL, Pavan FR, Pessoa JC, Garcia MH, Tomaz AI, Correia I, Acilan C. May iron(III) complexes containing phenanthroline derivatives as ligands be prospective anticancer agents? Eur J Med Chem 2019; 176:492-512. [DOI: 10.1016/j.ejmech.2019.04.070] [Citation(s) in RCA: 21] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/29/2018] [Revised: 02/18/2019] [Accepted: 04/29/2019] [Indexed: 02/08/2023]
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4
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Poreba M, Szalek A, Kasperkiewicz P, Rut W, Salvesen GS, Drag M. Small Molecule Active Site Directed Tools for Studying Human Caspases. Chem Rev 2015; 115:12546-629. [PMID: 26551511 DOI: 10.1021/acs.chemrev.5b00434] [Citation(s) in RCA: 57] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
Caspases are proteases of clan CD and were described for the first time more than two decades ago. They play critical roles in the control of regulated cell death pathways including apoptosis and inflammation. Due to their involvement in the development of various diseases like cancer, neurodegenerative diseases, or autoimmune disorders, caspases have been intensively investigated as potential drug targets, both in academic and industrial laboratories. This review presents a thorough, deep, and systematic assessment of all technologies developed over the years for the investigation of caspase activity and specificity using substrates and inhibitors, as well as activity based probes, which in recent years have attracted considerable interest due to their usefulness in the investigation of biological functions of this family of enzymes.
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Affiliation(s)
- Marcin Poreba
- Department of Bioorganic Chemistry, Faculty of Chemistry, Wroclaw University of Technology , Wyb. Wyspianskiego 27, 50-370 Wroclaw, Poland
| | - Aleksandra Szalek
- Department of Bioorganic Chemistry, Faculty of Chemistry, Wroclaw University of Technology , Wyb. Wyspianskiego 27, 50-370 Wroclaw, Poland
| | - Paulina Kasperkiewicz
- Department of Bioorganic Chemistry, Faculty of Chemistry, Wroclaw University of Technology , Wyb. Wyspianskiego 27, 50-370 Wroclaw, Poland
| | - Wioletta Rut
- Department of Bioorganic Chemistry, Faculty of Chemistry, Wroclaw University of Technology , Wyb. Wyspianskiego 27, 50-370 Wroclaw, Poland
| | - Guy S Salvesen
- Program in Cell Death and Survival Networks, Sanford Burnham Prebys Medical Discovery Institute , La Jolla, California 92037, United States
| | - Marcin Drag
- Department of Bioorganic Chemistry, Faculty of Chemistry, Wroclaw University of Technology , Wyb. Wyspianskiego 27, 50-370 Wroclaw, Poland
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5
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Tajon C, Jun YW, Craik CS. Single-molecule sensing of caspase activation in live cells via plasmon coupling nanotechnology. Methods Enzymol 2015; 544:271-97. [PMID: 24974294 DOI: 10.1016/b978-0-12-417158-9.00011-x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 04/14/2023]
Abstract
Apoptotic caspases execute programmed cell death, where low levels of caspase activity are linked to cancer (Kasibhatla & Tseng, 2003). Chemotherapies utilize induction of apoptosis as a key mechanism for cancer treatment, where caspase-3 is a major player involved in dismantling these aberrant cells. The ability to sensitively measure the initial caspase-3 cleavage events during apoptosis is important for understanding the initiation of this complex cellular process; however, current ensemble methods are not sensitive enough to measure single cleavage events in cells. To overcome this, we describe a procedure to develop peptide-linked gold nanoparticles that have unique optical properties and can serve as beacons to visualize the apoptotic drug response in cancer cells at the single-molecule level. By thorough analyses of their trajectories, one can reveal early-stage caspase-3 activation in live cells continuously and with no ambiguity.
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Affiliation(s)
- Cheryl Tajon
- Department of Pharmaceutical Chemistry, University of California, San Francisco, California, USA; Graduate Program in Chemistry and Chemical Biology, University of California, San Francisco, California, USA
| | - Young-Wook Jun
- Graduate Program in Chemistry and Chemical Biology, University of California, San Francisco, California, USA; Department of Otolaryngology, University of California, San Francisco, California, USA
| | - Charles S Craik
- Department of Pharmaceutical Chemistry, University of California, San Francisco, California, USA; Graduate Program in Chemistry and Chemical Biology, University of California, San Francisco, California, USA.
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6
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Brauchle E, Thude S, Brucker SY, Schenke-Layland K. Cell death stages in single apoptotic and necrotic cells monitored by Raman microspectroscopy. Sci Rep 2014; 4:4698. [PMID: 24732136 PMCID: PMC3986703 DOI: 10.1038/srep04698] [Citation(s) in RCA: 182] [Impact Index Per Article: 18.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/22/2013] [Accepted: 04/01/2014] [Indexed: 12/12/2022] Open
Abstract
Although apoptosis and necrosis have distinct features, the identification and discrimination of apoptotic and necrotic cell death in vitro is challenging. Immunocytological and biochemical assays represent the current gold standard for monitoring cell death pathways; however, these standard assays are invasive, render large numbers of cells and impede continuous monitoring experiments. In this study, both room temperature (RT)-induced apoptosis and heat-triggered necrosis were analyzed in individual Saos-2 and SW-1353 cells by utilizing Raman microspectroscopy. A targeted analysis of defined cell death modalities, including early and late apoptosis as well as necrosis, was facilitated based on the combination of Raman spectroscopy with fluorescence microscopy. Spectral shifts were identified in the two cell lines that reflect biochemical changes specific for either RT-induced apoptosis or heat-mediated necrosis. A supervised classification model specified apoptotic and necrotic cell death based on single cell Raman spectra. To conclude, Raman spectroscopy allows a non-invasive, continuous monitoring of cell death, which may help shedding new light on complex pathophysiological or drug-induced cell death processes.
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Affiliation(s)
- Eva Brauchle
- Fraunhofer-Institute for Interfacial Engineering and Biotechnology (IGB), Department of Cell and Tissue Engineering, Nobelstr. 12, 70569 Stuttgart, Germany
- University of Stuttgart, Institute of Interfacial Process Engineering and Plasma Technology (IGVP), Nobelstr. 12, 70569 Stuttgart, Germany
| | - Sibylle Thude
- Fraunhofer-Institute for Interfacial Engineering and Biotechnology (IGB), Department of Cell and Tissue Engineering, Nobelstr. 12, 70569 Stuttgart, Germany
| | - Sara Y. Brucker
- University Women's Hospital, Eberhard-Karls-University Tübingen, Silcherstr. 7/1, 72076 Tübingen, Germany
| | - Katja Schenke-Layland
- Fraunhofer-Institute for Interfacial Engineering and Biotechnology (IGB), Department of Cell and Tissue Engineering, Nobelstr. 12, 70569 Stuttgart, Germany
- University Women's Hospital, Eberhard-Karls-University Tübingen, Silcherstr. 7/1, 72076 Tübingen, Germany
- Department of Medicine/Cardiology, Cardiovascular Research Laboratories, David Geffen School of Medicine at UCLA, 675 Charles E. Young Drive South, MRL 3645, Los Angeles, CA, USA
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7
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Abstract
A neuron is able to seamlessly respond to a number of signals, in a timely and specific manner. This process, of integrating multiple inputs, relays on the orchestration of intracellular events by signaling networks. The inherent complexity of signaling networks has made computational modeling a useful approach to understand their underlying regulatory principles. Recent advances in imaging techniques have highlighted the nonhomogeneous nature of intracellular signaling and its significant contribution to the maintenance of signal specificity. Computational modeling can provide mechanistic insight into the origins of these inhomogeneous distributions of signaling components and their role in the integrative capabilities of the neuron.
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Affiliation(s)
- Wendy C Wenderski
- Department of Pharmacology and System Therapeutics, Friedman Brain Institute, Systems Biology Center of New York, Mount Sinai School of Medicine, New York, New York, USA
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8
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Welser K, Adsley R, Moore BM, Chan WC, Aylott JW. Protease sensing with nanoparticle based platforms. Analyst 2010; 136:29-41. [PMID: 20877821 DOI: 10.1039/c0an00429d] [Citation(s) in RCA: 59] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Nanoparticulate systems in various unique configurations are highly effective at detecting protease activity both in vivo and in vitro. In this article, we have summarised the conventional modern methods for monitoring protease activity, and critically appraised recent advances in protease-responsive nanosensors.
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Affiliation(s)
- Katharina Welser
- School of Pharmacy, Centre for Biomolecular Sciences, University of Nottingham, University Park, Nottingham, UK NG7 2RD
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9
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Gradients of a Ubiquitin E3 Ligase Inhibitor and a Caspase Inhibitor Determine Differentiation or Death in Spermatids. Dev Cell 2010; 19:160-73. [DOI: 10.1016/j.devcel.2010.06.009] [Citation(s) in RCA: 68] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/03/2009] [Revised: 03/25/2010] [Accepted: 05/04/2010] [Indexed: 11/21/2022]
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10
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Features of programmed cell death in intact Xenopus oocytes and early embryos revealed by near-infrared fluorescence and real-time monitoring. Cell Death Differ 2010; 17:170-9. [PMID: 19730443 PMCID: PMC2794955 DOI: 10.1038/cdd.2009.120] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Abstract
Factors influencing apoptosis of vertebrate eggs and early embryos have been studied in cell-free systems and in intact embryos by analyzing individual apoptotic regulators or caspase activation in static samples. A novel method for monitoring caspase activity in living Xenopus oocytes and early embryos is described here. The approach, using microinjection of a near-infrared caspase substrate that emits fluorescence only after its proteolytic cleavage by active effector caspases, has enabled the elucidation of otherwise cryptic aspects of apoptotic regulation. In particular, we show that brief caspase activity (10 min) is sufficient to cause apoptotic death in this system. We illustrate a cytochrome c dose threshold in the oocyte, which is lowered by Smac, a protein that binds thereby neutralizing the inhibitor of apoptosis proteins. We show that meiotic oocytes develop resistance to cytochrome c, and that the eventual death of oocytes arrested in meiosis is caspase-independent. Finally, data acquired through imaging caspase activity in the Xenopus embryo suggest that apoptosis in very early development is not cell-autonomous. These studies both validate this assay as a useful tool for apoptosis research and reveal subtleties in the cell death program during early development. Moreover, this method offers a potentially valuable screening modality for identifying novel apoptotic regulators.
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11
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Naoghare PK, Ki HA, Paek SM, Tak YK, Suh YG, Kim SG, Lee KH, Song JM. Simultaneous quantitative monitoring of drug-induced caspase cascade pathways in carcinoma cells. Integr Biol (Camb) 2009; 2:46-57. [PMID: 20473412 DOI: 10.1039/b916481b] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
Caspases are the key mediators of apoptosis. The caspase cascade includes a series of events leading to the activation of initiator and downstream caspases in a cell. Analysis of the caspase cascade in intact cells, however, has generally been limited as the simultaneous monitoring of upstream and downstream caspases is not well executed. In an effort to monitor the activation of caspase cascades in an intact cell, high-content cellular imaging that allows simultaneous quantitative monitoring of caspase activation has been developed. This has great significance for the exploration of various cellular caspases involved in apoptotic pathways as possible therapeutic targets in the process of drug discovery. To explore the potential of simultaneous monitoring of caspase-mediated apoptotic pathways, human myeloid leukemia HL-60 cells were treated with SH-03 {(7S,7aR,13aS)-9,10-dimethoxy-3,3-dimethyl-7,7a,13,13a-tetrahydro-3H-chromeno [3,4-b]pyrano[2,3-h]chromen-7-ol} (a newly synthesized candidate), camptothecin or naringenin (agents known to induce apoptosis) with or without caspase inhibitors. SH-03 or naringenin treatment initiated the caspase cascade through an intrinsic apoptotic pathway, whereas camptothecin treatment triggered both intrinsic and extrinsic caspase cascades. We now report a new approach based on uniform threshold intensity distribution that facilitates rapid, quantitative monitoring of drug-induced caspase cascades through multi-spectral and multicolor imaging cytometry.
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Affiliation(s)
- Pravin K Naoghare
- Research Institute of Pharmaceutical Sciences and College of Pharmacy, Seoul National University, Seoul 151-742, South Korea
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12
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Continuous imaging of plasmon rulers in live cells reveals early-stage caspase-3 activation at the single-molecule level. Proc Natl Acad Sci U S A 2009; 106:17735-40. [PMID: 19805121 DOI: 10.1073/pnas.0907367106] [Citation(s) in RCA: 170] [Impact Index Per Article: 11.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
The use of plasmon coupling in metal nanoparticles has shown great potential for the optical characterization of many biological processes. Recently, we have demonstrated the use of "plasmon rulers" to observe conformational changes of single biomolecules in vitro. Plasmon rulers provide robust signals without photobleaching or blinking. Here, we show the first application of plasmon rulers to in vivo studies to observe very long trajectories of single biomolecules in live cells. We present a unique type of plasmon ruler comprised of peptide-linked gold nanoparticle satellites around a core particle, which was used as a probe to optically follow cell-signaling pathways in vivo at the single-molecule level. These "crown nanoparticle plasmon rulers" allowed us to continuously monitor trajectories of caspase-3 activity in live cells for over 2 h, providing sufficient time to observe early-stage caspase-3 activation, which was not possible by conventional ensemble analyses.
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13
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Distinguishing between apoptosis and necrosis using a capacitance sensor. Biosens Bioelectron 2009; 24:2586-91. [DOI: 10.1016/j.bios.2009.01.028] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/25/2008] [Accepted: 01/08/2009] [Indexed: 11/22/2022]
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14
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Kawai H, Suzuki T, Kobayashi T, Ishii-Watabe A, Sakurai H, Ohata H, Honda K, Momose K, Hayakawa T, Kawanishi T. Caspase cascade proceeds rapidly after cytochrome c release from mitochondria in tumor necrosis factor-alpha-induced cell death. J Pharmacol Sci 2007; 103:159-67. [PMID: 17287591 DOI: 10.1254/jphs.fp0060877] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022] Open
Abstract
The caspase activation cascade and mitochondrial changes are major biochemical reactions in the apoptotic cell death machinery. We attempted to clarify the temporal relationship between caspase activation, cytochrome c release, mitochondrial depolarization, and morphological changes that take place during tumor necrosis factor (TNF)-alpha-induced cell death in HeLa cells. These reactions were analyzed at the single-cell level with 0.5 - 1 min resolution by using green fluorescent protein (GFP)-variant-derived probes and chemical probes. Cytochrome c release, caspase activation, and cellular shrinkage were always observed in this order within 10 min in all dying cells. This sequence of events was thus considered a critical pathway of cell death. Mitochondrial depolarization was also observed in all dying cells observed, but frequently occurred after caspase activation and cellular shrinkage. Mitochondrial depolarization is therefore likely to be a reaction that does not induce caspase activation and subsequent cellular shrinkage. Mitochondrial changes are important for apoptotic cell death; moreover, cytochrome c release, and not depolarization, is a key reaction related to cell death. In addition, we also found that the apoptotic pathway proceeds only when cells are exposed to TNF-alpha. These findings suggest that the entire cell death process proceeds rapidly during TNF-alpha exposure.
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Affiliation(s)
- Hiroshi Kawai
- Division of Biological Chemistry and Biologicals, National Institute of Health Sciences, Tokyo 158-8501, Japan.
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15
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Elphick LM, Meinander A, Mikhailov A, Richard M, Toms NJ, Eriksson JE, Kass GEN. Live cell detection of caspase-3 activation by a Discosoma-red-fluorescent-protein-based fluorescence resonance energy transfer construct. Anal Biochem 2006; 349:148-55. [PMID: 16386699 DOI: 10.1016/j.ab.2005.11.031] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/20/2005] [Revised: 10/26/2005] [Accepted: 11/21/2005] [Indexed: 11/29/2022]
Abstract
A probe consisting of Discosoma red fluorescent protein (DsRed) and enhanced yellow fluorescent protein (EYFP) linked by a 19-amino-acid chain containing the caspase-3 cleavage site Asp-Glu-Val-Asp was developed to monitor caspase-3 activation in living cells. The expression of the tandem construct in mammalian cells yielded a strong red fluorescence when excited with 450- to 490-nm light or with a 488-nm argon ion laser line as a result of fluorescence resonance energy transfer (FRET) from donor EYFP to acceptor DsRed. The advantage over previous constructs using cyan fluorescent protein is that our construct can be used when excitation wavelengths lower than 488nm are not available. To validate the construct, murine HT-22 hippocampal neuronal cells were triggered to undergo CD95-induced neuronal death. An increase in caspase-3 activity was demonstrated by a reduction of FRET in cells transfected with the construct. This was manifested by a dequenching of EYFP fluorescence leading to an increase in EYFP emission and a corresponding decrease in DsRed fluorescence, which correlated with an increase in pro-caspase-3 processing. We conclude that CD95-induced caspase-3 activation in HT-22 cells was readily detected at the single-cell level using the DsRed-EYFP-based FRET construct, making this a useful technology to monitor caspase-3 activity in living cells.
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Affiliation(s)
- Lucy M Elphick
- School of Biomedical and Molecular Sciences, University of Surrey, Guildford GU2 7XH, UK
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16
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Protein-Protein Interactions In Vivo: Use of Biosensors Based on FRET. ACTA ACUST UNITED AC 2006. [DOI: 10.1007/0-387-33016-x_15] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register]
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17
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Kohl T, Haustein E, Schwille P. Determining protease activity in vivo by fluorescence cross-correlation analysis. Biophys J 2005; 89:2770-82. [PMID: 16055538 PMCID: PMC1366777 DOI: 10.1529/biophysj.105.061127] [Citation(s) in RCA: 62] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
To date, most biochemical approaches to unravel protein function have focused on purified proteins in vitro. Whereas they analyze enzyme performance under assay conditions, they do not necessarily tell us what is relevant within a living cell. Ideally, cellular functions should be examined in situ. In particular, association/dissociation reactions are ubiquitous, but so far there is no standard technique permitting online analysis of these processes in vivo. Featuring single-molecule sensitivity combined with intrinsic averaging, fluorescence correlation spectroscopy is a minimally invasive technique ideally suited to monitor proteins. Moreover, endogenous fluorescence-based assays can be established by genetically encoding fusions of autofluorescent proteins and cellular proteins, thus avoiding the disadvantages of in vitro protein labeling and subsequent delivery to cells. Here, we present an in vivo protease assay as a model system: Green and red autofluorescent proteins were connected by Caspase-3- sensitive and insensitive protein linkers to create double-labeled protease substrates. Then, dual-color fluorescence cross-correlation spectroscopy was employed to study the protease reaction in situ. Allowing assessment of multiple dynamic parameters simultaneously, this method provided internal calibration and improved experimental resolution for quantifying protein stability. This approach, which is easily extended to reversible protein-protein interactions, seems very promising for elucidating intracellular protein functions.
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Affiliation(s)
- Tobias Kohl
- Max-Planck Institute for Experimental Medicine, Göttingen, Germany
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18
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Kawai H, Suzuki T, Kobayashi T, Mizuguchi H, Hayakawa T, Kawanishi T. Simultaneous imaging of initiator/effector caspase activity and mitochondrial membrane potential during cell death in living HeLa cells. BIOCHIMICA ET BIOPHYSICA ACTA-MOLECULAR CELL RESEARCH 2004; 1693:101-10. [PMID: 15313012 DOI: 10.1016/j.bbamcr.2004.05.009] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/26/2004] [Revised: 05/19/2004] [Accepted: 05/28/2004] [Indexed: 11/19/2022]
Abstract
A family of cystein proteases, the caspases, plays a central role in mediating cell death. In this study, we measured the activation of the initiator and effector caspase in real time, and studied the relationship between caspase activity and mitochondrial membrane potential in living cells by means of bioimaging. We also designed and developed a fluorescence resonance energy transfer (FRET)-based genetically encoded fluorescent indicator, which consisted of yellow fluorescent protein (YFP), a peptide sequence which can be cleaved by specific caspases, and cyan fluorescent protein (CFP). Two peptide sequences which could be cleaved by initiator caspases and effector caspases, respectively, were used. Simultaneous real-time measurements of the caspase activity and mitochondrial membrane potential in the cells treated with TNF-alpha and staurosporine revealed that dying cells showed caspase activation and mitochondrial depolarization, and that these events, however, were not firmly linked. Although it takes anywhere from 1 to over 10 h after the addition of the cell death inducer for the caspases to begin to be activated, initiator caspases and effector caspases are activated within a short period of time at the last stage in the entire process leading to cell death.
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Affiliation(s)
- Hiroshi Kawai
- Division of Biological Chemistry and Biologicals, National Institute of Health Sciences, 1-18-1 Kamiyoga, Setagaya, Tokyo 158-8501, Japan. kawai.nihs.go.jp
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19
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Zhang B. Design of FRET-based GFP probes for detection of protease inhibitors. Biochem Biophys Res Commun 2004; 323:674-8. [PMID: 15369803 DOI: 10.1016/j.bbrc.2004.08.143] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/03/2004] [Indexed: 11/26/2022]
Abstract
In this study, tandem Green fluorescent protein (GFP) fusion proteins were designed to detect proteolytic activity of thrombin based on the principle of fluorescence resonance energy transfer (FRET). The thrombin-specific recognition sequence, LVPR, was strategically placed in between a cyan-emitting mutant of the green fluorescent protein and an enhanced yellow-emitting fluorescent protein to allow thrombin-specific cleavage with detectable changes of FRET signal. A 4.6-fold increase of fluorescence emission ratio was observed upon addition of thrombin. This FRET-based probe was further tested for dose-dependent effects of thrombin specific inhibitor, hirudin. Our result showed a nice correlation between fluorescence emission ratios and concentrations of hirudin with subnanomolar sensitivity. We propose that FRET-based GFP probes can be used for high-throughput screening of protease inhibitors.
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Affiliation(s)
- Bin Zhang
- Institute of Basic Medical Sciences, Zhejiang University School of Medicine, 353 Yan'an Road, Hangzhou 310031, PR China.
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20
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Abstract
Apoptosis pathways activated by death receptors of the tumour necrosis factor (TNF) family such as Fas, TNFR1, or the TRAIL receptors DR4 and DR5 are implicated in diverse diseases. These are also the best-understood apoptosis pathways and many of our ideas about apoptosis regulation come from studying these pathways. Cell killing from such receptors occurs because of recruitment to the receptor of the adaptor protein FADD, which in turn recruits the pro form of caspase-8. Aggregation of pro-caspase-8 leads to its auto-activation and subsequent activation of effector caspases such as caspase-3. The apoptotic signal can be amplified through the mitochondria and inhibited through the action of competing molecules such as the inhibitor c-FLIP, which binds to the receptor complex in place of caspase-8. This simple mechanism explains much of the cell death that is induced by death receptors. However, recent studies indicate that we must incorporate new information into this model. Some examples that add new layers of complexity will be discussed in this review.
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Affiliation(s)
- Andrew Thorburn
- Department of Cancer Biology and Comprehensive Cancer Center, Wake Forest University, Medical Center Boulevard, Winston-Salem, NC 27157, USA.
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21
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He L, Wu X, Meylan F, Olson DP, Simone J, Hewgill D, Siegel R, Lipsky PE. Monitoring caspase activity in living cells using fluorescent proteins and flow cytometry. THE AMERICAN JOURNAL OF PATHOLOGY 2004; 164:1901-13. [PMID: 15161627 PMCID: PMC1615789 DOI: 10.1016/s0002-9440(10)63751-0] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Abstract
A molecular probe was developed to monitor caspase activity in living cells by flow cytometry. It consists of CFP and YFP with a peptide linker containing two caspase-cleavage sites (LEVD). Its expression resulted in intense fluorescence resonance energy transfer (FRET), whereas cleavage of this linker by caspases eliminated FRET because of physical separation of the CFP and YFP moieties. Using flow cytometry, cells expressing this probe exhibited two patterns, strong FRET and diminished or absent FRET. The appearance of diminished FRET was inhibited by a pan-caspase inhibitor z-VAD or D->A mutations in the LEVD sequence and was markedly increased by apoptosis-inducing agents, etoposide and camptothecin, or overexpression of a caspase 8-red fluorescent protein fusion protein. Importantly, this probe's ability to monitor caspase activity was comparable with results obtained with fluorogenic substrates or fluorochrome-labeled inhibitors of caspases. Specific caspase inhibitors indicated the probe was highly sensitive to cleavage by caspase 6 and 8, less sensitive to caspase 4, and resistant to other caspases. Activation of caspase 8 by Fas engagement markedly increased the probe's cleavage, whereas treatment of caspase 8-deficient cells with anti-Fas did not increase cleavage. However, staurosporine induced cleavage of the probe in caspase 8-deficient cells by a mechanism that was inhibited by overexpression of bcl-x. Taken together, the data indicate that this caspase-sensitive probe can be used to monitor the basal and apoptosis-related activities of caspases, including an initiator caspase, caspase 8, and effector caspases, such as caspase 6.
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Affiliation(s)
- Liusheng He
- Flow Cytometry Section, Office of Science and Technology, National Institute of Arthritis and Musculosketal and Skin Diseases, National Institute of Health, Bethesda, Maryland 20892, USA.
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22
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Köhler M, Zaitsev SV, Zaitseva II, Leibiger B, Leibiger IB, Turunen M, Kapelioukh IL, Bakkman L, Appelskog IB, de Monvel JB, Imreh G, Berggren PO. On-line monitoring of apoptosis in insulin-secreting cells. Diabetes 2003; 52:2943-50. [PMID: 14633855 DOI: 10.2337/diabetes.52.12.2943] [Citation(s) in RCA: 19] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
Apoptosis was monitored in intact insulin-producing cells both with microfluorometry and with two-photon laser scanning microscopy (TPLSM), using a fluorescent protein based on fluorescence resonance energy transfer (FRET). TPLSM offers three-dimensional spatial information that can be obtained relatively deep in tissues. This provides a potential for future in vivo studies of apoptosis. The cells expressed a fluorescent protein (C-DEVD-Y) consisting of two fluorophores, enhanced cyan fluorescent protein (ECFP) and enhanced yellow fluorescent protein (EYFP), linked by the amino acid sequence DEVD selectively cleaved by caspase-3-like proteases. FRET between ECFP and EYFP in C-DEVD-Y could therefore be monitored on-line as a sensor of caspase-3 activation. The relevance of using caspase-3 activation to indicate beta-cell apoptosis was demonstrated by inhibiting caspase-3-like proteases with Z-DEVD-fmk and thereby showing that caspase-3 activation was needed for high-glucose-and cytokine-induced apoptosis in the beta-cell and for staurosporine-induced apoptosis in RINm5F cells. In intact RINm5F cells expressing C-DEVD-Y and in MIN6 cells expressing the variant C-DEVD-Y2, FRET was lost at 155 +/- 23 min (n = 9) and 257 +/- 59 min (n = 4; mean +/- SE) after activation of apoptosis with staurosporine (6 micromol/l), showing that this method worked in insulin-producing cells.
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Affiliation(s)
- Martin Köhler
- Department of Molecular Medicine, Karolinska Institutet, Karolinska Hospital, Stockholm, Sweden.
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23
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Zurgil N, Sunray M, Shafran Y, Afrimzon E, Deutsch M. A novel approach for on line monitoring of apoptotic cell shrinkage in individual live lymphocytes. J Immunol Methods 2003; 281:37-49. [PMID: 14580880 DOI: 10.1016/s0022-1759(03)00263-1] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
The apoptotic process occurs asynchronically in most cell populations and its duration is variable. Therefore, the ability to continuously monitor the death process occurring in individual blood cells before, during and following apoptosis induction is crucial in the evaluation of the efficiency of pro- or anti-apoptotic drugs. We applied a kinetic approach by performing real time measurements of individual living cells. This approach is based on an easy and unique method for monitoring intracellular staining reaction, which accompanied early apoptotic cell shrinkage. The intracellular enzymatic reaction rates were determined by taking repeated, sequential measurements of fluorescence intensity of the same individual cells. These rates were found to correlate with the respective radii of the cells under different conditions, and to decrease following apoptosis induction. The ability to remeasure the same cell before and after apoptosis induction enabled the detection of specific individual lymphocytes, which were more susceptible or resistant to pro-apoptotic stimulus.
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Affiliation(s)
- Naomi Zurgil
- The Biophysical Interdisciplinary Jerome Schottenstein Center for the Research and Technology of the Cellome, Department of Physics, Bar Ilan University, 52900 Ramat Gan, Israel
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24
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Thorburn J, Bender LM, Morgan MJ, Thorburn A. Caspase- and serine protease-dependent apoptosis by the death domain of FADD in normal epithelial cells. Mol Biol Cell 2003; 14:67-77. [PMID: 12529427 PMCID: PMC140228 DOI: 10.1091/mbc.e02-04-0207] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Abstract
The adapter protein FADD consists of two protein interaction domains: a death domain and a death effector domain. The death domain binds to activated death receptors such as Fas, whereas the death effector domain binds to procaspase 8. An FADD mutant, which consists of only the death domain (FADD-DD), inhibits death receptor-induced apoptosis. FADD-DD can also activate a mechanistically distinct, cell type-specific apoptotic pathway that kills normal but not cancerous prostate epithelial cells. Here, we show that this apoptosis occurs through activation of caspases 9, 3, 6, and 7 and a serine protease. Simultaneous inhibition of caspases and serine proteases prevents FADD-DD-induced death. Inhibition of either pathway alone does not prevent cell death but does affect the morphology of the dying cells. Normal prostate epithelial cells require both the caspase and serine protease inhibitors to efficiently prevent apoptosis in response to TRAIL. In contrast, the serine protease inhibitor does not affect TRAIL-induced death in prostate tumor cells suggesting that the FADD-DD-dependent pathway can be activated by TRAIL. This apoptosis pathway is activated in a cell type-specific manner that is defective in cancer cells, suggesting that this pathway may be targeted during cancer development.
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Affiliation(s)
- Jacqueline Thorburn
- Department of Cancer Biology and Comprehensive Cancer Center, Wake Forest University School of Medicine, Winston-Salem, North Carolina 27157, USA
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25
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Grabarek J, Darzynkiewicz Z. In situ activation of caspases and serine proteases during apoptosis detected by affinity labeling their enzyme active centers with fluorochrome-tagged inhibitors. Exp Hematol 2002; 30:982-9. [PMID: 12225789 DOI: 10.1016/s0301-472x(02)00886-x] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
Abstract
Activation of caspases is the key event of apoptosis. To detect this event in situ we applied fluorochrome-labeled inhibitors of caspases (FLICA) as affinity labels of active centers of these enzymes. The FLICA are fluorescein- or sulforhodamine-conjugated peptide-fluoromethyl ketones that covalently, with 1:1 stoichiometry, bind to enzymatic centers of caspases; the specificity is provided by the peptide sequence of amino acids. Similarly, we applied fluorescent inhibitors of serine proteases (FLISP) to detect active sites of the latter enzymes. Exposure of live cells to FLICA of FLISP led to uptake of these ligands and their binding to activated caspases or active sites of serine proteases; the unbound reagents were removed by cell rinse. Only cells undergoing apoptosis were labeled with FLISP or FLICA. Intracellular binding sites of FLICA are consistent with known localization of caspases. Covalent binding of FLICA or FLISP allowed us to identify the labeled proteins by immunoblotting: the proteins that bound individual FLICAs had molecular weight between 17 and 22 kDa, which corresponds to large subunits of the caspases; two proteins reacting with FLISP were about 57 and 60 kDa, which suggests that they are novel enzymes. Detection of caspases or serine proteases activation can be combined with other markers of apoptosis or cell cycle for multiparametric analysis by flow or laser scanning cytometry. Being caspase inhibitors, FLICA arrest the process of apoptosis and prevent cell disintegration. The stathmo-apoptotic assay was developed, therefore, to obtain cumulative apoptotic index over a long period of time and estimate a rate of cell entry into apoptosis for cell populations.
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Affiliation(s)
- Jerzy Grabarek
- Brander Cancer Research Institute at New York Medical College, Valhalla, NY, USA
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26
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Rehm M, Dussmann H, Janicke RU, Tavare JM, Kogel D, Prehn JHM. Single-cell fluorescence resonance energy transfer analysis demonstrates that caspase activation during apoptosis is a rapid process. Role of caspase-3. J Biol Chem 2002; 277:24506-14. [PMID: 11964393 DOI: 10.1074/jbc.m110789200] [Citation(s) in RCA: 235] [Impact Index Per Article: 10.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
Activation of effector caspases is considered to be the final step in many apoptosis pathways. We transfected HeLa cells with a recombinant caspase substrate composed of cyan and yellow fluorescent protein and a linker peptide containing the caspase cleavage sequence DEVD, and we examined the cleavage kinetics at the single-cell level by fluorescence resonance energy transfer (FRET) analysis. Caspase activation in response to tumor necrosis factor-alpha, staurosporine, or etoposide resulted in cleavage of the linker peptide and subsequent disruption of the FRET signal. The time to caspase activation varied among individual cells, depending on the type of treatment and concentration used. However, once initiated, disruption of the FRET signal was always rapid (<or=15 min) and largely independent of these parameters. In contrast, FRET probe cleavage was significantly slower in the caspase-3-deficient MCF-7 cells, particularly at low concentrations of the pro-apoptotic agents. Under these conditions, MCF-7 cells required up to 90 min for the FRET probe cleavage, whereas MCF-7/Casp-3 cells displayed rapid cleavage kinetics. Interestingly, we could still observe comparable cell death rates in MCF-7 and MCF-7/Casp-3 cells. Our results suggest that caspase activation during apoptosis occurs in an "all or nothing" fashion. Caspase-3 is required for rapid cleavage kinetics when the onset of apoptosis is slow, suggesting the existence of caspase-3-dependent feedback loops.
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Affiliation(s)
- Markus Rehm
- Interdisciplinary Center for Clinical Research (IZKF), Research Group "Apoptosis and Cell Death," the Department of Experimental Dermatology, Division of Immunology and Cell Biology, Westphalian Wilhelms University, D-48149 Münster, Germany
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27
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Grabarek J, Amstad P, Darzynkiewicz Z. Use of fluorescently labeled caspase inhibitors as affinity labels to detect activated caspases. Hum Cell 2002; 15:1-12. [PMID: 12126059 DOI: 10.1111/j.1749-0774.2002.tb00094.x] [Citation(s) in RCA: 35] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Activation of caspases is the key event of apoptosis and different approaches were developed to assay it. To detect their activation in situ, we applied fluorochrome labeled inhibitors of caspases (FLICA) as affinity labels of active centers of these enzymes. The FLICA ligands are fluorescein or sulforhodamine conjugated peptide-fluoromethyl ketones that covalently bind to enzymatic centers of caspases with 1:1 stoichiometry. The specificity of FLICA towards individual caspases is provided by the peptide sequence of amino acids. Exposure of live cells to FLICA results in uptake of these ligands and their binding to activated caspases; unbound FLICA is removed by cell rinse. Cells labeled with FLICA can be examined by fluorescence microscopy or subjected to quantitative analysis by cytometry. Intracellular binding sites of FLICA are consistent with known localization of caspases. Covalent binding of FLICA allowed us to identify the labeled proteins by immunoblotting: the proteins that bound individual FLICAs had molecular weight between 17 and 22 kDa, which corresponds to large subunits of the caspases. Detection of caspases activation by FLICA can be combined with other markers of apoptosis or cell cycle for multiparametric analysis. Because FLICA are caspase inhibitors they arrest the process of apoptosis preventing cell disintegration. The stathmo-apoptotic method was developed, therefore, that allows one to assay cumulative apoptotic index over long period of time and estimate the rate of cell entry into apoptosis for large cell populations. FLICA offers a rapid and convenient assay of caspases activation and can also be used to accurately estimate the incidence of apoptosis.
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28
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Morgan MJ, Thorburn J, Thomas L, Maxwell T, Brothman AR, Thorburn A. An apoptosis signaling pathway induced by the death domain of FADD selectively kills normal but not cancerous prostate epithelial cells. Cell Death Differ 2001; 8:696-705. [PMID: 11464214 DOI: 10.1038/sj.cdd.4400866] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/23/2000] [Revised: 02/06/2001] [Accepted: 02/20/2001] [Indexed: 12/28/2022] Open
Abstract
The adaptor protein FADD directly, or indirectly via another adaptor called TRADD, recruits caspase 8 to death receptors of the tumor necrosis factor receptor family. Consequentially, a dominant-negative mutant (FADD-DN, which consists only of the FADD death domain) that binds to receptors but cannot recruit caspase 8 has been widely used to inhibit apoptosis by various stimuli that work via death receptors. Here, we show that FADD-DN also has another cell type- and cancer-dependent activity because it induces apoptosis of normal human prostate epithelial cells but not normal prostate stromal cells or prostate cancer cells. This activity is independent of FADD-DN's ability to bind to three known interacting proteins, Fas, TRADD or RIP suggesting that it is distinct from FADD's functions at activated death receptors. FADD-DN induces caspase activation in normal epithelial cells as demonstrated using a Fluorescence Resonance Energy Transfer assay that measures caspase activity in individual living cells. However, caspase-independent pathways are also implicated in FADD-DN-induced apoptosis because caspase inhibitors were inefficient at preventing prostate cell death. Therefore, the death domain of FADD has a previously unrecognized role in cell survival that is epithelial-specific and defective in cancer cells. This FADD-dependent signaling pathway may be important in prostate carcinogenesis.
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Affiliation(s)
- M J Morgan
- Huntsman Cancer Institute, Department of Oncological Sciences, University of Utah, Salt Lake City, UT 84112, USA
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