Exposure of cells to static magnetic field accelerates loss of integrity of plasma membrane during apoptosis

Teodori, Laura; Grabarek, Jerzy; Smolewski, Piotr; Ghibelli, Lina; Bergamaschi, Antonio; Nicola, Milena De; Darzynkiewicz, Zbigniew

doi:10.1002/cyto.10160

Cited by 69 publications

(47 citation statements)

References 34 publications

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“…At this regard, our undergoing studies demonstrated that the magnetic exposure of human peripheral blood in vitro, altered the cholesterol level of the plasma. Furthermore the deep pits observed at the highest SMF intensity might account for the decreased membrane integrity and increased permeability to impermeant dyes we have observed in a previous study (11).…”

Section: Discussionsupporting

confidence: 54%

Static magnetic fields affect cell size, shape, orientation, and membrane surface of human glioblastoma cells, as demonstrated by electron, optic, and atomic force microscopy

et al. 2006

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Background: It is common knowledge that static magnetic fields (SMF) do not interact with living cells; thus, fewer studies of SMF compared with variable magnetic fields are carried out. However, evidence demonstrated that SMF affect cellular structures. To investigate the effect of exposure to increasing doses of SMF on cell morphology, human glioblastoma cells were exposed to SMF ranging between 80 and 3,000 G (8 and 300 mT). Methods: Cell morphology of human glioblastoma cells, derived from a primary culture, was studied by electron and optic microscopy. FITC-phalloidin staining of actin filaments was also investigated. Finally, cell surface structure changes were detected by atomic force microscopy.Results: Scanning electron microscopy demonstrated a dose-dependent cell shape modification, progressive cell detachment, loss of the long villi, and appearance of membrane roughness and blebs. FITC-phalloidin staining confirmed the villi retention and cell dimension decrease. At

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Section: Discussionsupporting

confidence: 54%

Static magnetic fields affect cell size, shape, orientation, and membrane surface of human glioblastoma cells, as demonstrated by electron, optic, and atomic force microscopy

et al. 2006

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“…According to product manuals, these membrane-permeable and nontoxic inhibitors enter the cell and bind covalently to the reactive cysteine residue that resides on the large subunit of the active caspase heterodimer. This system undoubtedly represents a useful research tool to monitor apoptosis progression (4)(5)(6)(7)(8)(9)(10)(11)(12)(13)(14). It was also used to study the intracellular localization of caspases and their changes during the apoptosis (15).…”

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confidence: 99%

Labeling of apoptotic JURL‐MK1 cells by fluorescent caspase‐3 inhibitor FAM‐DEVD‐fmk occurs mainly at site(s) different from caspase‐3 active site

2007

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Fluorochrome-labeled inhibitors of caspases (FLICA) have been designed as an alternative tool for the detection of caspase activation in whole cells. They should label the active site of the corresponding caspase through a covalent attachment to the reactive cysteine residue. One of the FLICAs, FAM-DEVD-fmk, was used to monitor apoptosis progression in leukemic JURL-MK1 cells by means of flow cytometry. The effects of unlabeled caspase inhibitors z-DEVD-fmk and z-VAD-fmk on FLICA staining were analyzed to evaluate the contribution of caspase-bound FLICA to the fluorescent signal. Covalent binding of inhibitors to caspase-3 subunit was revealed by Western blotting. Although the unlabeled inhibitors irreversibly bind to caspase-3, completely inhibit its activity, and prevent FLICA binding to caspase-3 even at concentrations lower than 5 lM, they have no effect on FLICA staining of apoptotic cells. Fluorescent signal of FLICA is characteristic for apoptotic cells but originates mainly from yet unspecified site(s) that differ from the caspase active site. This finding puts in doubt the specificity of staining by various FLICAs with regard to individual caspases and shows the need for an extreme care in the interpretation of data obtained using these labels. ' 2007International Society for Analytical Cytology Key termsFLICA; apoptosis; JURL-MK1; Imatinib; z-DEVD-fmk; z-VAD-fmk; flow cytometry; Western blotting CASPASES are widely considered to be the key mediators of apoptosis. This enzyme family participates in a series of reactions that are triggered in response to proapoptotic signals and result in the cleavage of protein substrates and finally in the controlled disassembly of the cell. Caspases are synthesized as inactive precursors (procaspases) that undergo proteolytic maturation upon apoptotic stimulation.Detection of caspase activation provides a useful assay for analyzing one of the earliest known biochemical events associated with apoptosis. The cleavage of procaspases into the active fragments can be observed on immunoblots. Anticaspase antibodies which specifically recognize the active enzyme forms are also available for use in immunoblotting as well as in flow cytometry. Alternatively, the enzyme activity rather than its presence can be monitored by means of fluorogenic substrates generating strong fluorescence signal upon cleavage by caspases. Another approach to study activation of caspases in situ utilizes fluorescently labeled irreversible caspase inhibitors (1,2). Fluorochrome-labeled inhibitors of caspases (FLICA) have been designed as affinity labels of the enzyme active center and consist of a short peptide, a fluoromethylketone (fmk) moiety, and a fluorescent tag, usually carboxyfluorescein (FAM) or fluorescein isothiocyanate (FITC). The amino acid composition of the peptide reflects the substrate

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“…Comparative studies with FCM and LSC have shown that data obtained by both technologies are consistent with each other for the study of apoptosis or necrosis (30). LSC is a reliable tool for the intracellular staining of p53 protein (31) and DNA ploidy analysis (32).…”

Section: Discussionmentioning

confidence: 58%

Scanning fluorescent microscopy analysis is applicable for absolute and relative cell frequency determinations

et al. 2004

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Background: Flow cytometry (FCM) and laser scanning cytometry (LSC) are the routine techniques for fluorescent cell analysis. Recently, we developed a scanning fluorescent microscopy (SFM) technique. This study compares SFM to LSC (two slide-based cytometry, SBC, techniques) and FCM, in experimental and clinical settings. Methods: For the relative cell-frequency determinations, HT29 colorectal cancer cells and Ficoll separated blood mononuclear cells (FSBMCs) were serially diluted (from 1:1 to 1:1,000) and measured by each of the three techniques. For the absolute cell number determinations (only for SBC) FSBMCs were smeared on slides, then HT29 cells were placed on the slide with a micromanipulator (5-50 cells). Tumor cells circulating in the peripheral blood were isolated by magnetic separation from clinical blood samples of colorectal cancer patients. All samples were double-stained by CD45 ECD and CAM5.2 FITC antibodies. For slides,

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Exposure of cells to static magnetic field accelerates loss of integrity of plasma membrane during apoptosis

Abstract: Much attention is being paid to the biologic effects of magnetic fields (MFs). Although MFs enhance tumorigenesis, they are neither mutagenic nor tumorigenic. The mechanism of their tumorigenic effect has not been elucidated

Cited by 69 publications

References 34 publications

Static magnetic fields affect cell size, shape, orientation, and membrane surface of human glioblastoma cells, as demonstrated by electron, optic, and atomic force microscopy

Static magnetic fields affect cell size, shape, orientation, and membrane surface of human glioblastoma cells, as demonstrated by electron, optic, and atomic force microscopy

Labeling of apoptotic JURL‐MK1 cells by fluorescent caspase‐3 inhibitor FAM‐DEVD‐fmk occurs mainly at site(s) different from caspase‐3 active site

Scanning fluorescent microscopy analysis is applicable for absolute and relative cell frequency determinations

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