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Cancer Epidemiology, Biomarkers &... Jul 2007Loss or attenuation of cell cycle checkpoint function can compromise the fidelity of DNA due to insufficient time to repair DNA damage. We evaluated cell cycle... (Comparative Study)
Comparative Study
Loss or attenuation of cell cycle checkpoint function can compromise the fidelity of DNA due to insufficient time to repair DNA damage. We evaluated cell cycle checkpoints in 747 patients with lung cancer and 745 controls by measuring the proportions of cultured peripheral blood lymphocytes in G2-M and S phases. As an indicator of G2-M phase or S phase cell cycle checkpoint function, the gamma-radiation-induced cell accumulation index at G2-M or S phase was defined as (percentage of cells in G2-M or S with ionizing radiation exposure - percentage of cells in G2-M or S without ionizing radiation exposure) / (percentage of cells in G2-M or S without ionizing radiation exposure). We found that the median cell accumulation index was significantly lower in patients than that in controls at both the G2-M phase (0.774 versus 0.882, P = 0.002) and the S phase (0.226 versus 0.243, P = 0.001). When the median value for the cell accumulation index at the G2-M or S phase in the controls was used as the cutoff point, the reduced indices at G2-M and S phases were associated with 1.28-fold (95% confidence interval, 1.04-1.58) and 1.30-fold (95% confidence interval, 1.06-1.61) increased lung cancer risks, respectively. Analyses stratified by histology showed some heterogeneity. Additionally, cell accumulation indices at both G2-M and S phases were not associated with clinical stages. We conclude that attenuated functions of G2-M and S cell cycle checkpoints might be susceptibility markers for lung cancer.
Topics: Carcinoma, Non-Small-Cell Lung; Case-Control Studies; Cell Division; Dose-Response Relationship, Radiation; Female; G2 Phase; Gamma Rays; Humans; Lung Neoplasms; Lymphocytes; Male; Middle Aged; Risk Factors; S Phase
PubMed: 17627019
DOI: 10.1158/1055-9965.EPI-07-0111 -
The Journal of Biological Chemistry Aug 2014Mitotic progression is regulated largely through dynamic and reversible protein phosphorylation that is modulated by opposing actions of protein kinases and...
Mitotic progression is regulated largely through dynamic and reversible protein phosphorylation that is modulated by opposing actions of protein kinases and phosphatases. In this study, we show that phosphatase 1 nuclear targeting subunit (Pnuts) functions as a master regulator of mitosis by modulating protein phosphatase 1 (PP1). Overexpression of Pnuts in Xenopus egg extracts inhibited both mitotic and meiotic exit. Immunodepletion of Pnuts from egg extracts revealed its essential functions in mitotic entry and maintenance. The level of Pnuts oscillates during the cell cycle and peaks in mitosis. Pnuts destruction during M-phase exit is mediated by the anaphase-promoting complex/cyclosome (APC/C)-targeted ubiquitination and proteolysis, and conserved destruction motifs of Pnuts. Disruption of Pnuts degradation delayed M-phase exit, suggesting it as an important mechanism to permit M-phase exit.
Topics: Animals; Base Sequence; Cell Division; DNA Primers; DNA-Binding Proteins; Meiosis; Mitosis; Nuclear Proteins; Proteolysis; RNA-Binding Proteins; Ubiquitination; Xenopus
PubMed: 25002584
DOI: 10.1074/jbc.M114.572149 -
PloS One 2015KPU-300 is a novel colchicine-type anti-microtubule agent derived from plinabulin (NPI-2358). We characterized the effects of KPU-300 on cell cycle kinetics and...
KPU-300, a Novel Benzophenone-Diketopiperazine-Type Anti-Microtubule Agent with a 2-Pyridyl Structure, Is a Potent Radiosensitizer That Synchronizes the Cell Cycle in Early M Phase.
KPU-300 is a novel colchicine-type anti-microtubule agent derived from plinabulin (NPI-2358). We characterized the effects of KPU-300 on cell cycle kinetics and radiosensitization using HeLa cells expressing the fluorescent ubiquitination-based cell cycle indicator (Fucci). Cells treated with 30 nM KPU-300 for 24 h were efficiently synchronized in M phase and contained clearly detectable abnormal Fucci fluorescence. Two-dimensional flow-cytometric analysis revealed a fraction of cells distinct from the normal Fucci fluorescence pattern. Most of these cells were positive for an M phase marker, the phosphorylated form of histone H3. Cells growing in spheroids responded similarly to the drug, and the inner quiescent fraction also responded after recruitment to the growth fraction. When such drug-treated cells were irradiated in monolayer, a remarkable radiosensitization was observed. To determine whether this radiosensitization was truly due to the synchronization in M phase, we compared the radiosensitivity of cells synchronized by KPU-300 treatment and cells in early M phase isolated by a combined method that took advantage of shake-off and the properties of the Fucci system. Following normalization against the surviving fraction of cells treated with KPU-300 alone, the surviving fractions of cells irradiated in early M phase coincided. Taken together with potential vascular disrupting function in vivo, we propose a novel radiosensitizing strategy using KPU-300.
Topics: Benzophenones; Cell Cycle; Cell Division; Cell Line, Tumor; Diketopiperazines; Flow Cytometry; Fluorescent Antibody Technique; HeLa Cells; Humans; Microtubules; Radiation-Sensitizing Agents
PubMed: 26716455
DOI: 10.1371/journal.pone.0145995 -
Biochemical and Biophysical Research... Nov 2012Plinabulin (NPI-2358) is a novel microtubule-depolymerizing agent. In HeLa cells, plinabulin arrests the cell-cycle at M phase and subsequently induces mitotic...
Unusual expression of red fluorescence at M phase induced by anti-microtubule agents in HeLa cells expressing the fluorescent ubiquitination-based cell cycle indicator (Fucci).
Plinabulin (NPI-2358) is a novel microtubule-depolymerizing agent. In HeLa cells, plinabulin arrests the cell-cycle at M phase and subsequently induces mitotic catastrophe. To better understand the effects on this compound on the cell-cycle, we used the fluorescent ubiquitination-based cell cycle indicator (Fucci), which normally enables G1 and S/G2/M cells to emit red and green fluorescence, respectively. When HeLa-Fucci cells were treated with 50 nM plinabulin, cells began to fluoresce both green and red in an unusual pattern; most cells exhibited the new pattern after 24 h of treatment. X-irradiation efficiently induced G2 arrest in plinabulin-treated cells and significantly retarded the emergence of the unusual pattern, suggesting that entering M phase is essential for induction of the pattern. By simultaneously visualizing chromosomes with GFP-histone H2B, we established that the pattern emerges after nuclear envelope breakdown but before metaphase. Pedigree assay revealed a significant relationship between the unusual expression and mitotic catastrophe. Nocodazole, KPU-133 (a more potent derivative of plinabulin), and paclitaxel also exerted similar effects. From these data, we conclude that the unusual pattern may be associated with dysregulation of late M phase-specific E3 ligase activity and mitotic catastrophe following treatment with anti-microtubule agents.
Topics: Cell Division; Diketopiperazines; Fluorescence; HeLa Cells; Humans; Luminescent Proteins; Microtubules; Mitosis; Nocodazole; Tubulin Modulators; Ubiquitin-Protein Ligases
PubMed: 23063846
DOI: 10.1016/j.bbrc.2012.10.014 -
EMBO Reports Nov 2023Chromosome segregation errors in mammalian oocyte meiosis lead to developmentally compromised aneuploid embryos and become more common with advancing maternal age. Known...
Chromosome segregation errors in mammalian oocyte meiosis lead to developmentally compromised aneuploid embryos and become more common with advancing maternal age. Known contributors include age-related chromosome cohesion loss and spindle assembly checkpoint (SAC) fallibility in meiosis-I. But how effective the SAC is in meiosis-II and how this might contribute to age-related aneuploidy is unknown. Here, we developed genetic and pharmacological approaches to directly address the function of the SAC in meiosis-II. We show that the SAC is insensitive in meiosis-II oocytes and that as a result misaligned chromosomes are randomly segregated. Whilst SAC ineffectiveness in meiosis-II is not age-related, it becomes most prejudicial in oocytes from older females because chromosomes that prematurely separate by age-related cohesion loss become misaligned in meiosis-II. We show that in the absence of a robust SAC in meiosis-II these age-related misaligned chromatids are missegregated and lead to aneuploidy. Our data demonstrate that the SAC fails to prevent cell division in the presence of misaligned chromosomes in oocyte meiosis-II, which explains how age-related cohesion loss can give rise to aneuploid embryos.
Topics: Female; Animals; Spindle Apparatus; M Phase Cell Cycle Checkpoints; Meiosis; Oocytes; Chromatids; Aneuploidy; Chromosome Segregation; Mammals
PubMed: 37795949
DOI: 10.15252/embr.202357227 -
Alcohol and Alcoholism (Oxford,... 1999We found previously that short-term (3 and 6 h) exposure to ethanol (100 and 200 mM) induced the transient arrest of L929 cells at the G2+M phase. To identify the exact...
We found previously that short-term (3 and 6 h) exposure to ethanol (100 and 200 mM) induced the transient arrest of L929 cells at the G2+M phase. To identify the exact site blocked during the G2+M phase, we carried out flow cytometry and microscopic analysis with asynchronous L929 cells exposed to ethanol (12.5-330 mM) for 3, 6 or 24 h. Flow cytometry (the simultaneous analysis of cellular DNA and cyclin B1 content) revealed that the percentage of 4c (tetraploid) cells with a high level of cyclin B1 increased after continuous 6 h exposure to ethanol (> or =82.5 mM) and decreased after 24 h exposure, which supports the idea of a transient M-phase block. To determine the sub-M phase of 4c cells with high levels of cyclin B1 based on spindle microtubules and their karyotype, we viewed immunofluorescent images by double staining with Hoechst 33258 (bis-benzimide trihydrochloride) for DNA and with fluorescein isothiocyanate-labelled antibody for cyclin B1 or beta-tubulin. A 6 h exposure to intermediate concentrations (50-100 mM) of ethanol increased the number of early-anaphase cells, compared with the control, suggesting an inhibition of the elongation of polar microtubules. Both 6 and 24 h exposure to higher concentrations (100-200 mM) of ethanol increased metaphase cells, indicating an arrest at the spindle assembly checkpoint and suggesting an inhibition of the shortening of kinetochore microtubules and/or the degradation of cyclin B . Moreover, 6 h exposure to 330 mM ethanol increased round, probably early-prophase, cells, suggesting inhibition of the formation of spindle microtubules. Thus, it is likely that higher concentrations of ethanol affect the elongation, contraction, and formation of the spindle microtubules of L929 cells dose-dependently and also disrupt the correlation between microtubule organization and the synthesis and degradation of cyclin B1, thereby delaying the progress of karyokinesis, which may lead to an ethanol-induced G2+M block.
Topics: Cell Division; Cell Size; Cells, Cultured; Cyclin B; Dose-Response Relationship, Drug; Ethanol; Flow Cytometry; Fluorescent Antibody Technique; Humans; Interphase; Karyotyping; Microscopy, Fluorescence; Microtubules; Mitosis; Time Factors
PubMed: 10414604
DOI: 10.1093/alcalc/34.3.300 -
Environmental Science and Pollution... Mar 2015Titanium dioxide has been classified in the 2B group as a possible human carcinogen by the International Agency for Research on Cancer, and amid concerns of its...
Titanium dioxide has been classified in the 2B group as a possible human carcinogen by the International Agency for Research on Cancer, and amid concerns of its exposure, cell cycle alterations are an important one. However, several studies show inconclusive effects, mainly because it is difficult to compare cell cycle effects caused by TiO2 nanoparticle (NP) exposure between different shapes and sizes of NP, cell culture types, and time of exposure. In addition, cell cycle is frequently analyzed without cell cycle synchronization, which may also mask some effects. We hypothesized that synchronization after TiO2 NP exposure could reveal dissimilar cell cycle progression when compared with unsynchronized cell population. To test our hypothesis, we exposed lung epithelial cells to 1 and 10 μg/cm(2) TiO2 NPs for 7 days and one population was synchronized by serum starvation and inhibition of ribonucleotide reductase using hydroxyurea. Another cell population was exposed to TiO2 NPs under the same experimental conditions, but after treatments, cell cycle was analyzed without synchronization. Our results showed that TiO2 NP-exposed cells without synchronization had no changes in cell cycle distribution; however, cell population synchronized after 1 and 10 μg/cm(2) TiO2 NP treatment showed a 1.5-fold and 1.66-fold increase, respectively, in proliferation. Synchronized cells also reveal a faster capability of TiO2 NP-exposed cells to increase cell population in the G2/M phase in the following 9 h after synchronization. We conclude that synchronization discloses a greater percentage of cells in the G2/M phase and higher proliferation than TiO2 NP-synchronized cells.
Topics: Cell Cycle; Cell Division; Cell Line, Tumor; Epithelial Cells; Humans; Lung; Mitosis; Nanoparticles; Titanium; Toxicity Tests
PubMed: 25422119
DOI: 10.1007/s11356-014-3871-y -
The New England Journal of Medicine Aug 1995
Review
Topics: Cell Division; Humans; Oncogenes; Phosphorylation; Signal Transduction
PubMed: 7596376
DOI: 10.1056/NEJM199508033330508 -
Current Biology : CB Dec 2016Alternation between DNA replication in the mother cell (S phase) and equal partitioning of the replicated chromosomes to the daughter cells (M phase) during eukaryotic...
Alternation between DNA replication in the mother cell (S phase) and equal partitioning of the replicated chromosomes to the daughter cells (M phase) during eukaryotic cell division is governed by switches that flip protein kinases on and off. New work reveals that the M-phase promoting kinase is opposed by a phosphatase that also participates in a bistable switching mechanism.
Topics: Animals; Cell Division; Chromosomes; DNA Replication; Eukaryotic Cells; Gene Expression Regulation, Enzymologic; Protein Kinases; S Phase
PubMed: 27997836
DOI: 10.1016/j.cub.2016.11.007 -
Biochemical and Biophysical Research... May 2008In order to understand the importance of the cytosolic and nuclear-specific O-linked N-acetylglucosaminylation (O-GlcNAc) on cell cycle regulation, we recently reported...
In order to understand the importance of the cytosolic and nuclear-specific O-linked N-acetylglucosaminylation (O-GlcNAc) on cell cycle regulation, we recently reported that inhibition of O-GlcNAc transferase (OGT) delayed or blocked Xenopus laevis oocyte germinal vesicle breakdown (GVBD). Here, we show that increased levels of the long OGT isoform (ncOGT) accelerate X. laevis oocyte GVBD. A N-terminally truncated isoform (sOGT) with a similar in vitro catalytic activity towards a synthetic CKII-derived peptide had no effect, illustrating the important role played by the N-terminal tetratrico-peptide repeats. ncOGT microinjection in the oocytes increases both the speed and extent of O-GlcNAc addition, leads to a quicker activation of the MPF and MAPK pathways and finally results in a faster GVBD. Microinjection of anti-OGT antibodies leads to a delay of the GVBD kinetics. Our results hence demonstrate that OGT is a key molecule for the timely progression of the cell cycle.
Topics: Acetylglucosamine; Animals; Cell Division; Cells, Cultured; Microinjections; N-Acetylglucosaminyltransferases; Oocytes; Recombinant Proteins; Xenopus laevis
PubMed: 18298951
DOI: 10.1016/j.bbrc.2008.02.063