Transient inhibition of DNA synthesis results in increased dihydrofolate reductase synthesis and subsequent increased DNA content per cell.

We examined the role that blockage of cells in the cell cycle may play in the stimulation of gene amplification and enhancement of drug resistance. We found that several different inhibitors of DNA synthesis, which were each able to block cells at the G1-S-phase boundary, induced an enhanced cycloheximide-sensitive synthesis of an early S-phase cell cycle-regulated enzyme, dihydrofolate reductase, and of other proteins as well. This response was specific, in that blockage at the G2 phase did not result in overproduction of the enzyme. When the cells were released from drug inhibition, DNA synthesis resumed, resulting in a cycloheximide-sensitive elevation in DNA content per cell. We speculate that the excess DNA synthesis (which could contribute to events detectable later as gene amplification) is a consequence of the accumulation of S-phase-specific proteins in the affected cells, which may then secondarily influence the pattern of DNA replication.

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Alterations in the cell cycle of mouse cumulus granulosa cells during expansion and mucification in vivo and in vitro

Reproduction Fertility and Development ◽

10.1071/rd9960935 ◽

1996 ◽

Vol 8 (6) ◽

pp. 935 ◽

Cited By ~ 25

Author(s):

AW Schuetz ◽

DG Whittingham ◽

R Snowden

Keyword(s):

Cell Cycle ◽

Dna Synthesis ◽

Granulosa Cells ◽

Dna Content ◽

Cumulus Cell ◽

Cumulus Cells ◽

Ovarian Follicles ◽

S Phase

The cell cycle characteristics of mouse cumulus granulosa cells were determined before, during and following their expansion and mucification in vivo and in vitro. Cumulus-oocyte complexes (COC) were recovered from ovarian follicles or oviducts of prepubertal mice previously injected with pregnant mare serum gonadotrophin (PMSG) or a mixture of PMSG and human chorionic gonadotrophin (PMSG+hCG) to synchronize follicle differentiation and ovulation. Cell cycle parameters were determined by monitoring DNA content of cumulus cell nuclei, collected under rigorously controlled conditions, by flow cytometry. The proportion of cumulus cells in three cell cycle-related populations (G0/G1; S; G2/M) was calculated before and after exposure to various experimental conditions in vivo or in vitro. About 30% of cumulus cells recovered from undifferentiated (compact) COC isolated 43-45 h after PMSG injections were in S phase and 63% were in G0/G1 (2C DNA content). Less than 10% of the cells were in the G2/M population. Cell cycle profiles of cumulus cells recovered from mucified COC (oviducal) after PMSG+hCG-induced ovulation varied markedly from those collected before hCG injection and were characterized by the relative absence of S-phase cells and an increased proportion of cells in G0/G1. Cell cycle profiles of cumulus cells collected from mucified COC recovered from mouse ovarian follicles before ovulation (9-10 h after hCG) were also characterized by loss of S-phase cells and an increased G0/G1 population. Results suggest that changes in cell cycle parameters in vivo are primarily mediated in response to physiological changes that occur in the intrafollicular environment initiated by the ovulatory stimulus. A similar lack of S-phase cells was observed in mucified cumulus cells collected 24 h after exposure in vitro of compact COC to dibutyryl cyclic adenosine monophosphate (DBcAMP), follicle-stimulating hormone or epidermal growth factor (EGF). Additionally, the proportion of cumulus cells in G2/M was enhanced in COC exposed to DBcAMP, suggesting that cell division was inhibited under these conditions. Thus, both the G1-->S-phase and G2-->M-phase transitions in the cell cycle appear to be amenable to physiological regulation. Time course studies revealed dose-dependent changes in morphology occurred within 6 h of exposure in vitro of COC to EGF or DBcAMP. Results suggest that the disappearance of the S-phase population is a consequence of a decline in the number of cells beginning DNA synthesis and exit of cells from the S phase following completion of DNA synthesis. Furthermore, loss of proliferative activity in cumulus cells appears to be closely associated with COC expansion and mucification, whether induced under physiological conditions in vivo or in response to a range of hormonal stimuli in vitro. The observations indicate that several signal-transducing pathways mediate changes in cell cycle parameters during cumulus cell differentiation.

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GTP Induces S-phase Cell-cycle Arrest and Inhibits DNA Synthesis in K562 Cells But Not in Normal Human Peripheral Lymphocytes

BMB Reports ◽

10.5483/bmbrep.2006.39.5.492 ◽

2006 ◽

Vol 39 (5) ◽

pp. 492-501 ◽

Cited By ~ 12

Author(s):

Mohammad Amin Moosavi ◽

Razieh Yazdanparast ◽

Abbas Lotfi

Keyword(s):

Cell Cycle ◽

Dna Synthesis ◽

Cell Cycle Arrest ◽

K562 Cells ◽

S Phase ◽

Phase Cell ◽

Peripheral Lymphocytes ◽

Cycle Arrest ◽

Human Peripheral Lymphocytes ◽

Normal Human

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Intracellular free Ca2+ in the cell cycle in human fibroblasts: transitions between G1 and G0 and progression into S phase.

Molecular Biology of the Cell ◽

10.1091/mbc.4.3.293 ◽

1993 ◽

Vol 4 (3) ◽

pp. 293-302 ◽

Cited By ~ 28

Author(s):

M Wahl ◽

E Gruenstein

Keyword(s):

Cell Cycle ◽

Dna Synthesis ◽

Dose Response ◽

Human Fibroblasts ◽

S Phase ◽

Free Calcium ◽

Response Curves ◽

Serum Stimulation ◽

Inhibition Of Dna Synthesis ◽

Stimulation Of

Intracellular free calcium ([Ca2+]i) has been proposed to play an important part in the regulation of the cell cycle. Although a number of studies have shown that stimulation of quiescent cells with growth factors causes an immediate rise in [Ca2+]i (Rabinovitch et al., 1986; Vincentini and Villereal, 1986; Hesketh et al., 1988; Tucker et al., 1989, Wahl et al., 1990), a causal relationship between the [Ca2+]i transient and the ability of the cells to reenter the cell cycle has not been firmly established. We have found that blocking the mitogen-induced elevation of [Ca2+]i with the cytoplasmic [Ca2+]i buffer dimethyl BAPTA (dmBAPTA) also blocks subsequent entry of cells into S phase. The dose response curves for inhibition of serum stimulation of [Ca2+]i and DNA synthesis by dmBAPTA are virtually identical including an anomalous stimulation observed at low levels of dmBAPTA. Reversal of the [Ca2+]i buffering effect of dmBAPTA by transient exposure of the cells to the Ca2+ ionophore ionomycin also reverses the inhibition of DNA synthesis 20-24 h later. Ionomycin by itself does not stimulate DNA synthesis. These data are consistent with the conclusion that a transient increase in [Ca2+]i occurring shortly after serum stimulation of quiescent fibroblasts is necessary but not sufficient for subsequent entry of the cells into S phase. This study is the first to show a direct relationship between early serum stimulated Cai2+ increase and subsequent DNA synthesis in human cells. It also goes beyond recent studies on BALB/3T3 cells by providing dose response data and demonstrating reversibility, which are strong indications of a cause and effect relationship.

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Poly(ADP-ribose) Polymerase Activity Prevents Signaling Pathways for Cell Cycle Arrest after DNA Methylating Agent Exposure

Journal of Biological Chemistry ◽

10.1074/jbc.m413841200 ◽

2005 ◽

Vol 280 (16) ◽

pp. 15773-15785 ◽

Cited By ~ 49

Author(s):

Julie K. Horton ◽

Donna F. Stefanick ◽

Jana M. Naron ◽

Padmini S. Kedar ◽

Samuel H. Wilson

Keyword(s):

Cell Cycle ◽

Dna Synthesis ◽

Cell Cycle Arrest ◽

Signaling Pathways ◽

Dna Polymerase ◽

S Phase ◽

Dna Polymerase Β ◽

Cycle Arrest ◽

Parp Activity ◽

Inhibition Of Dna Synthesis

Mouse fibroblasts, deficient in DNA polymerase β, are hypersensitive to monofunctional DNA methylating agents such as methyl methanesulfonate (MMS). Both wild-type and, in particular, repair-deficient DNA polymerase β null cells are highly sensitized to the cytotoxic effects of MMS by 4-amino-1,8-naphthalimide (4-AN), an inhibitor of poly(ADP-ribose) polymerase (PARP) activity. Experiments with synchronized cells suggest that exposure during S-phase of the cell cycle is required for the 4-AN effect. 4-AN elicits a similar extreme sensitization to the thymidine analog, 5-hydroxymethyl-2′-deoxyuridine, implicating the requirement for an intermediate of DNA repair. In PARP-1-expressing fibroblasts treated with a combination of MMS and 4-AN, a complete inhibition of DNA synthesis is apparent after 4 h, and by 24 h, all cells are arrested in S-phase of the cell cycle. Continuous incubation with 4-AN is required to maintain the cell cycle arrest. Caffeine, an inhibitor of the upstream checkpoint kinases ATM (ataxia telangiectasia-mutated) and ATR (ATM and Rad3-related), has no effect on the early inhibition of DNA synthesis, but cells are no longer able to maintain the block after 8 h. Instead, the addition of caffeine leads to arrest of cells in G2/M rather than S-phase after 24 h. Analysis of signaling pathways in cell extracts reveals an activation of Chk1 after treatment with MMS and 4-AN, which can be suppressed by caffeine. Our results suggest that inhibition of PARP activity results in sensitization to MMS through maintenance of an ATR and Chk1-dependent S-phase checkpoint.

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Nuclear DNA synthesis in vitro is mediated via stable replication forks assembled in a temporally specific fashion in vivo

Molecular and Cellular Biology ◽

10.1128/mcb.8.5.1923-1931.1988 ◽

1988 ◽

Vol 8 (5) ◽

pp. 1923-1931

Author(s):

N H Heintz ◽

B W Stillman

Keyword(s):

Cell Cycle ◽

Dna Synthesis ◽

Dihydrofolate Reductase ◽

S Phase ◽

Replication Forks ◽

Chromosomal Dna ◽

Restriction Fragments ◽

Temporal Specificity

A cell-free nuclear replication system that is S-phase specific, that requires the activity of DNA polymerase alpha, and that is stimulated three- to eightfold by cytoplasmic factors from S-phase cells was used to examine the temporal specificity of chromosomal DNA synthesis in vitro. Temporal specificity of DNA synthesis in isolated nuclei was assessed directly by examining the replication of restriction fragments derived from the amplified 200-kilobase dihydrofolate reductase domain of methotrexate-resistant CHOC 400 cells as a function of the cell cycle. In nuclei prepared from cells collected at the G1/S boundary of the cell cycle, synthesis of amplified sequences commenced within the immediate dihydrofolate reductase origin region and elongation continued for 60 to 80 min. The order of synthesis of amplified restriction fragments in nuclei from early S-phase cells in vitro appeared to be indistinguishable from that in vivo. Nuclei prepared from CHOC 400 cells poised at later times in the S phase synthesized characteristic subsets of other amplified fragments. The specificity of fragment labeling patterns was stable to short-term storage at 4 degrees C. The occurrence of stimulatory factors in cytosol extracts was cell cycle dependent in that minimal stimulation was observed with early G1-phase extracts, whereas maximal stimulation was observed with cytosol extracts from S-phase cells. Chromosomal synthesis was not observed in nuclei from G1 cells, nor did cytosol extracts from S-phase cells induce chromosomal replication in G1 nuclei. In contrast to chromosomal DNA synthesis, mitochondrial DNA replication in vitro was not stimulated by cytoplasmic factors and occurred at equivalent rates throughout the G1 and S phases. These studies show that chromosomal DNA replication in isolated nuclei is mediated by stable replication forks that are assembled in a temporally specific fashion in vivo and indicate that the synthetic mechanisms observed in vitro accurately reflect those operative in vivo.

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Nuclear DNA synthesis in vitro is mediated via stable replication forks assembled in a temporally specific fashion in vivo.

Molecular and Cellular Biology ◽

10.1128/mcb.8.5.1923 ◽

1988 ◽

Vol 8 (5) ◽

pp. 1923-1931 ◽

Cited By ~ 22

Author(s):

N H Heintz ◽

B W Stillman

Keyword(s):

Cell Cycle ◽

Dna Synthesis ◽

Dihydrofolate Reductase ◽

S Phase ◽

Replication Forks ◽

Chromosomal Dna ◽

Restriction Fragments ◽

Temporal Specificity

A cell-free nuclear replication system that is S-phase specific, that requires the activity of DNA polymerase alpha, and that is stimulated three- to eightfold by cytoplasmic factors from S-phase cells was used to examine the temporal specificity of chromosomal DNA synthesis in vitro. Temporal specificity of DNA synthesis in isolated nuclei was assessed directly by examining the replication of restriction fragments derived from the amplified 200-kilobase dihydrofolate reductase domain of methotrexate-resistant CHOC 400 cells as a function of the cell cycle. In nuclei prepared from cells collected at the G1/S boundary of the cell cycle, synthesis of amplified sequences commenced within the immediate dihydrofolate reductase origin region and elongation continued for 60 to 80 min. The order of synthesis of amplified restriction fragments in nuclei from early S-phase cells in vitro appeared to be indistinguishable from that in vivo. Nuclei prepared from CHOC 400 cells poised at later times in the S phase synthesized characteristic subsets of other amplified fragments. The specificity of fragment labeling patterns was stable to short-term storage at 4 degrees C. The occurrence of stimulatory factors in cytosol extracts was cell cycle dependent in that minimal stimulation was observed with early G1-phase extracts, whereas maximal stimulation was observed with cytosol extracts from S-phase cells. Chromosomal synthesis was not observed in nuclei from G1 cells, nor did cytosol extracts from S-phase cells induce chromosomal replication in G1 nuclei. In contrast to chromosomal DNA synthesis, mitochondrial DNA replication in vitro was not stimulated by cytoplasmic factors and occurred at equivalent rates throughout the G1 and S phases. These studies show that chromosomal DNA replication in isolated nuclei is mediated by stable replication forks that are assembled in a temporally specific fashion in vivo and indicate that the synthetic mechanisms observed in vitro accurately reflect those operative in vivo.

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Involvement of the p38 MAPK signaling pathway in S-phase cell-cycle arrest induced by Furazolidone in human hepatoma G2 cells

Journal of Applied Toxicology ◽

10.1002/jat.2829 ◽

2012 ◽

Vol 33 (12) ◽

pp. 1500-1505 ◽

Cited By ~ 6

Author(s):

Yu Sun ◽

Shusheng Tang ◽

Xi Jin ◽

Chaoming Zhang ◽

Wenxia Zhao ◽

...

Keyword(s):

Cell Cycle ◽

Cell Cycle Arrest ◽

Signaling Pathway ◽

P38 Mapk ◽

Mapk Signaling ◽

S Phase ◽

Mapk Signaling Pathway ◽

Phase Cell ◽

Human Hepatoma ◽

Cycle Arrest

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S-Phase Cell Cycle Arrest, Apoptosis, and Molecular Mechanisms of Aplasia Ras homolog Member I–Induced Human Ovarian Cancer SKOV3 Cell Lines

International Journal of Gynecological Cancer ◽

10.1097/igc.0000000000000105 ◽

2014 ◽

Vol 24 (4) ◽

pp. 629-634 ◽

Cited By ~ 10

Author(s):

Qiaoying Zhu ◽

Jianming Hu ◽

Huijuan Meng ◽

Yufei Shen ◽

Jinhua Zhou ◽

...

Keyword(s):

Cell Cycle ◽

Ovarian Cancer ◽

Molecular Mechanisms ◽

Significant Inhibition ◽

S Phase ◽

Phase Cell ◽

Cell Cycle Distribution ◽

Human Ovarian Cancer ◽

Skov3 Cell ◽

Skov3 Cells

ObjectiveAplasia Ras homolog member I (ARHI) is associated with human ovarian cancer (HOC) growth and proliferation; however, the mechanisms are unclear. The purpose of this study was to investigateARHIeffects in HOC SKOV3 cells.MethodsWe transfected SKOV3 cells with PIRES2-EGFP-ARHI and measured growth inhibition rates, cell cycle distribution, apoptosis rates, and expression of P-STAT3 (phosphorylated signal transduction and activators of transcription 3) and P-ERK (phosphorylated extracellular signal regulated protein kinase).ResultsOur data showed significant inhibition of growth, significantly increased S-phase arrest and apoptosis rates, and reduction of P-STAT3 and P-ERK1/2 expression levels.ConclusionsWe propose the mechanism may involveARHI-induced phosphorylation of ERK1/2 and STAT3 protein kinases, thereby blocking proliferation signaling pathways, to induce HOC SKOV3 apoptosis.

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