Alina Grzanka

Features of senescence and cell death induced by doxorubicin in A549 cells: organization and level of selected cytoskeletal proteins

PurposeSenescence and cell death are fail-safe mechanisms protecting against tumorigenesis. Both these forms of cellular response could be induced in cancer cells, thus suppressing tumor progression. Therefore, to fully understand chemotherapeutic effects, not only symptoms of cell death, but also of senescence should be evaluated. Since the involvement of cytoskeleton components in these processes has been reported, changes in the organization and level of some cytoskeletal proteins may be indicative of cell fate.MethodsWe analyzed selected markers of senescence and cell death, including possible alterations in vimentin and G-actin cytoskeleton in A549 cells after treatment with doxorubicin. Light (SA-β-galactosidase), fluorescent (vimentin and G-actin labeling) and electron microscopic examinations along with flow cytometry methods (TUNEL, Annexin V/PI staining, cell cycle analysis, intracellular level of vimentin) were employed to determine the outcome of the treatment.ResultsUncoupling between senescent cell morphology and stable cell cycle arrest occurred. Some differences in the organization and level of cytoskeletal proteins, especially of vimentin, like fluctuations in its level, were observed. On the other hand, G-actin seemed to be more stable than vimentin.ConclusionsG-actin stability may imply its potential usefulness for permanent senescence detection. Along with slight to moderate cytoskeletal alterations, the obtained results suggest transient senescence-like state induction, followed by morphology typical of mitotic catastrophe in part of the A549 cells.

Phenethyl isothiocyanate-induced cytoskeletal changes and cell death in lung cancer cells

Isothiocyanates are known for their anticarcinogenic and antitumor potential, however, the exact mechanism of their action has not been fully elucidated. The present study was designed to investigate and compare the effects of phenethyl isothiocyanate on cell morphology, the cytoskeleton and induction of cell death in human non-small cell lung cancer cell lines A549 and H1299 differing in p53 status. Cell viability tests (MTT assay, xCELLigence system) showed that PEITC exhibits lower cytotoxicity to A549 cells containing wild-type p53. The observed growth-inhibitory effect of PEITC was dose-dependent, but time-dependence was observed only at higher concentrations. The results of flow-cytometric and fluorescence-microscopic analyses indicate that PEITC induced disassembly of actin stress fibers and degradation of tubulin which, most likely, contributed to the induction of cell death. Although, 24-h incubation caused G2/M cell cycle arrest, the fraction of G2/M cells decreased in a dose- and time-dependent manner in favor of cells with sub-G1 DNA content. Further experiments (Annexin V staining, electron microscopic observations) confirmed that the apoptosis-inducing potency of PEITC is probably the main factor responsible for cell growth inhibition. However, PEITC treatment also resulted in the appearance of an increased proportion of H1299 cells exhibiting morphological features of mitotic catastrophe.

Low-dose etoposide-treatment induces endoreplication and cell death accompanied by cytoskeletal alterations in A549 cells: Does the response involve senescence? The possible role of vimentin.

BackgroundSenescence in the population of cells is often described as a program of restricted proliferative capacity, which is manifested by broad morphological and biochemical changes including a metabolic shift towards an autophagic-like response and a genotoxic-stress related induction of polyploidy. Concomitantly, the cell cycle progression of a senescent cell is believed to be irreversibly arrested. Recent reports suggest that this phenomenon may have an influence on the therapeutic outcome of anticancer treatment. The aim of this study was to verify the possible involvement of this program in the response to the treatment of the A549 cell population with low doses of etoposide, as well as to describe accompanying cytoskeletal alterations.MethodsAfter treatment with etoposide, selected biochemical and morphological parameters were examined, including: the activity of senescence-associated ß-galactosidase, SAHF formation, cell cycle progression, the induction of p21Cip1/Waf1/Sdi1 and cyclin D1, DNA strand breaks, the disruption of cell membrane asymmetry/integrity and ultrastructural alterations. Vimentin and G-actin cytoskeleton was evaluated both cytometrically and microscopically.Results and conclusionsEtoposide induced a senescence-like phenotype in the population of A549 cells. Morphological alterations were nevertheless not directly coupled with other senescence markers including a stable cell cycle arrest, SAHF formation or p21Cip1/Waf1/Sdi1 induction. Instead, a polyploid, TUNEL-positive fraction of cells visibly grew in number. Also upregulation of cyclin D1 was observed. Here we present preliminary evidence, based on microscopic analyses, that suggest a possible role of vimentin in nuclear alterations accompanying polyploidization-depolyploidization events following genotoxic insults.

Paclitaxel and the dietary flavonoid fisetin: a synergistic combination that induces mitotic catastrophe and autophagic cell death in A549 non-small cell lung cancer cells

AbstractBackground The use of the dietary polyphenols as chemosensitizing agents to enhance the efficacy of conventional cytostatic drugs has recently gained the attention of scientists and clinicians as a plausible approach for overcoming the limitations of chemotherapy (e.g. drug resistance and cytotoxicity). The aim of this study was to investigate whether a naturally occurring diet-based flavonoid, fisetin, at physiologically attainable concentrations, could act synergistically with clinically achievable doses of paclitaxel to produce growth inhibitory and/or pro-death effects on A549 non-small cell lung cancer cells, and if it does, what mechanisms might be involved.MethodsThe drug–drug interactions were analyzed based on the combination index method of Chou and Talalay and the data from MTT assays. To provide some insights into the mechanism underlying the synergistic action of fisetin and paclitaxel, selected morphological, biochemical and molecular parameters were examined, including the morphology of cell nuclei and mitotic spindles, the pattern of LC3-II immunostaining, the formation of autophagic vacuoles at the electron and fluorescence microscopic level, the disruption of cell membrane asymmetry/integrity, cell cycle progression and the expression level of LC3-II, Bax, Bcl-2 and caspase-3 mRNA.ResultsHere, we reported the first experimental evidence for the existence of synergism between fisetin and paclitaxel in the in vitro model of non-small cell lung cancer. This synergism was, at least partially, ascribed to the induction of mitotic catastrophe. The switch from the cytoprotective autophagy to the autophagic cell death was also implicated in the mechanism of the synergistic action of fisetin and paclitaxel in the A549 cells. In addition, we revealed that the synergism between fisetin and paclitaxel was cell line-specific as well as that fisetin synergizes with arsenic trioxide, but not with mitoxantrone and methotrexate in the A549 cells.ConclusionsOur results provide rationale for further testing of fisetin in the combination with paclitaxel or arsenic trioxide to obtain detailed insights into the mechanism of their synergistic action as well as to evaluate their toxicity towards normal cells in an animal model in vivo. We conclude that this study is potentially interesting for the development of novel chemotherapeutic approach to non-small cell lung cancer.

Hyperthermia induces cytoskeletal alterations and mitotic catastrophe in p53-deficient H1299 lung cancer cells

Hyperthermia is used in cancer therapy, however much remains to be discovered regarding its mechanisms of action at the cellular level. In this study, the effects of hyperthermia on cell death, survival, morphology and the cytoskeleton were investigated in a non-small cell lung cancer cell line, H1299. Despite the fact that this cell line is widely used in research, it has not yet been tested for heat shock sensitivity. Cells were given a 30-min heat shock at 43.5°C and 45°C and left to recover at 37°C for 24 and 48 h. 24 h after heat shock treatment, we monitored changes in the organization of the cytoskeleton using immunofluorescence microscopy. The number of actin stress fibers was significantly reduced, microtubules formed a looser meshwork, a portion of the cells possessed multipolar mitotic spindles, whereas vimentin filaments collapsed into perinuclear complexes. 48 h following heat stress, most of the cells showed recovery of the cytoskeleton, however we observed a considerable number of giant cells that were multinucleated or contained one enlarged nucleus. The data obtained by MTT assay showed a dose-dependent decrease of cell viability, while flow cytometric analysis revealed an increase in the number of cells with externalized phosphatidylserine. The results suggest that one of the modes of heat-induced cell death in H1299 cells is mitotic catastrophe, which probably ends in apoptosis.

Actin distribution patterns in HL-60 leukemia cells treated with etoposide

Localization of actin was studied in HL-60 leukemia cells after treatment with the anticancer agent etoposide for 3 days in a range of concentrations (0.02-200 microM). Significant changes in morphology of the cells and F-actin distribution patterns labelled with TRITC-phalloidin occurred only after treatment with 100 and 200 microM etoposide. In comparison with control cells, the number of cells decreased, cells were larger and almost all treated cells had irregular surfaces with lamellipodia. F-actin was distributed in a punctate pattern throughout the cytoplasm after treatment. In some treated cells, fluorescence appeared as a bright haze, whereas in other cells it formed a network. Treated cells also showed bright fluorescence at their periphery. Immunogold labelling of actin was observed in cells whether or not treated with etoposide. Labelling was found in the nucleus and also in the cytoplasm. At the ultrastructural level, cells treated with 100 and 200 microM etoposide showed increased positivity for actin in relation with blebbing, margination of nuclear chromatin and bodies containing recognizable nuclear fragments. These findings indicate that alterations in expression of actin in HL-60 cells after treatment with etoposide is dose-dependent and related with apoptosis.

Hair follicle stem cells can be driven into a urothelial-like phenotype: an experimental study.

The aim of this study was to show that conditioned medium might induce transdifferentiation of hair follicle stem cells into urothelial‐like cells. Several conditioned media and culture conditions (skeletal muscle cell conditioned medium, smooth muscle cell conditioned medium, fibroblast conditioned medium, transforming growth factor‐conditioned medium, urothelial cell conditioned medium, and co‐culture of hair follicle stem cells and urothelial cells) were used. The hair follicle stem cells phenotype from rat whisker hair follicles was checked by using flow cytometry and immunofluorescence. Cytokeratins 7, 8, 15 and 18 were used as markers. Urothelial cell conditioned medium increased the expression of urothelial markers (cytokeratin 7, cytokeratin 8, cytokeratin 18), whereas it decreased a hair follicle stem cells marker (cytokeratin 15) after 2 weeks of culture. This process depended on the time of cultivation. This medium was able to sustain the epithelial phenotype of the culture. Other media including a co‐culture system failed to induce similar changes. Smooth muscle conditioned medium resulted in a loss of cells in culture. Hair follicle stem cells are capable of differentiating into urothelial‐like cells in vitro when exposed to a bladder‐specific microenvironment.

Ciprofloxacin is a potential topoisomerase II inhibitor for the treatment of NSCLC.

Lung cancer is one of the most common tumors and its treatment is still inefficient. In our previous work we proved that ciprofloxacin has a different influence on five cancer cell lines. Here, we aimed to compare the biological effect of ciprofloxacin on cell lines representing different responses after treatment, thus A549 was chosen as a sensitive model, C6 and B16 as highly resistant. Three different cell lines were analyzed (A549, B16 and C6). The characterization of continuous cell growth was analyzed with the Real-Time Cell Analyzer (RTCA)-DP system. Cytoskeletal changes were demonstrated using immunofluorescence. The cell cycle was analyzed using flow cytometry. Ciprofloxacin was cytostatic only against the A549 cell line. In the case of other tested cell lines a cytostatic effect was not observed. Cytoskeletal analysis confirms the results obtained with RTCA-DP. A549 cells were inhibited in the G2/M phase suggesting a mechanism related to topoisomerase II inhibition. The biological effects of ciprofloxacin support the hypothesis that this drug can serve as an adjuvant treatment for lung cancer, due to its properties enabling topoisomerase II inhibition.

Expression of cyclin A, B1 and D1 after induction of cell cycle arrest in the Jurkat cell line exposed to doxorubicin.

Jurkat human lymphoblastoid cells were incubated in increasing concentrations of doxorubicin (0.05, 0.1 and 0.15 μM) to induce cell death, and their expression of cyclin A, B1 and D1 was evaluated by flow cytometry (cell cycle progression, Annexin V assay, percentages and levels of each of the cyclins), transmission electron microscopy (ultrastructure) and confocal fluorescence microscopy (expression and intracellular localization of cyclins). After low‐dose doxorubicin treatment, Jurkat cells responded mainly by G2/M arrest, which was related to increased cyclin B1, A and D1 levels, a low level of apoptosis and/or mitotic catastrophe. The influence of doxorubicin on levels and/or localization of selected cyclins was confirmed, which may in turn contribute to the G2/M arrest induced by the drug.

Taxol-induced polyploidy and cell death in CHO AA8 cells.

The purpose of this study was to assess whether Taxol-induced changes in microtubular dynamics are accompanied by apoptosis. CHO AA8 cells were treated with different Taxol concentrations (0.25microM, 0.5microM, 1microM) for 24h. The effects of Taxol exposure were analyzed using fluorescence microscopy and flow cytometry (TUNEL and annexin V-FITC/propidium iodide assays). 0.25microM Taxol caused the appearance of few multinucleated giant cells exhibiting extensive arrays of fine filaments. Slight increases in the level of polyploidy, phosphatidylserine externalization and in the percentage of TUNEL positive cells were noticed. Concentrations of 0.5 and 1microM resulted in the appearance of a large number of giant cells, which exhibited, depending on the cell, an extensive microtubular network or loose or tightly packed bundles of microtubules. Cells of reduced volume and showing chromatin condensation were also seen. Cell cycle analysis revealed that almost half of the cell population was polyploid. Except in cells exposed to 1microM Taxol, annexin V-FITC/PI labelling did not reveal the loss of plasma membrane integrity or increase in phosphatidylserine externalization; however, TUNEL assay revealed a significant increase in the percentage of cells with DNA fragmentation. These data indicate that CHO AA8 cells treated with Taxol undergo cell death of a type which considerably differs from apoptosis.