Attenuation of G 2 -Phase Cell Cycle Checkpoint Control Is Associated with Increased Frequencies of Unrejoined Chromosome Breaks in Human Tumor Cells

Abstract Although it is well established that plant seeds treated with high doses of gamma radiation arrest development as seedlings, the cause of this arrest is unknown. The uvh1 mutant of Arabidopsis is defective in a homolog of the human repair endonuclease XPF, and uvh1 mutants are sensitive to both the toxic effects of UV and the cytostatic effects of gamma radiation. Here we find that gamma irradiation of uvh1 plants specifically triggers a G2-phase cell cycle arrest. Mutants, termed suppressor of gamma (sog), that suppress this radiation-induced arrest and proceed through the cell cycle unimpeded were recovered in the uvh1 background; the resulting irradiated plants are genetically unstable. The sog mutations fall into two complementation groups. They are second-site suppressors of the uvh1 mutant's sensitivity to gamma radiation but do not affect the susceptibility of the plant to UV radiation. In addition to rendering the plants resistant to the growth inhibitory effects of gamma radiation, the sog1 mutation affects the proper development of the pollen tetrad, suggesting that SOG1 might also play a role in the regulation of cell cycle progression during meiosis.

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Cdc5L interacts with ATR and is required for the S‐phase cell‐cycle checkpoint

EMBO Reports ◽

10.1038/embor.2009.122 ◽

2009 ◽

Vol 10 (9) ◽

pp. 1029-1035 ◽

Cited By ~ 51

Author(s):

Nianxiang Zhang ◽

Ramandeep Kaur ◽

Shamima Akhter ◽

Randy J Legerski

Keyword(s):

Cell Cycle ◽

S Phase ◽

Cell Cycle Checkpoint ◽

Phase Cell ◽

Cycle Checkpoint

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Histone Deacetylase Inhibitors Trigger a G2 Checkpoint in Normal Cells That Is Defective in Tumor Cells

Molecular Biology of the Cell ◽

10.1091/mbc.11.6.2069 ◽

2000 ◽

Vol 11 (6) ◽

pp. 2069-2083 ◽

Cited By ~ 178

Author(s):

Ling Qiu ◽

Andrew Burgess ◽

David P. Fairlie ◽

Helen Leonard ◽

Peter G. Parsons ◽

...

Keyword(s):

Cell Cycle ◽

Tumor Cells ◽

Histone Deacetylase ◽

Cell Cycle Progression ◽

Histone Deacetylase Inhibitors ◽

Cell Cycle Checkpoint ◽

Phase Cell ◽

Selective Toxicity ◽

Protective Mechanisms ◽

G2 Checkpoint

Important aspects of cell cycle regulation are the checkpoints, which respond to a variety of cellular stresses to inhibit cell cycle progression and act as protective mechanisms to ensure genomic integrity. An increasing number of tumor suppressors are being demonstrated to have roles in checkpoint mechanisms, implying that checkpoint dysfunction is likely to be a common feature of cancers. Here we report that histone deacetylase inhibitors, in particular azelaic bishydroxamic acid, triggers a G2 phase cell cycle checkpoint response in normal human cells, and this checkpoint is defective in a range of tumor cell lines. Loss of this G2 checkpoint results in the tumor cells undergoing an aberrant mitosis resulting in fractured multinuclei and micronuclei and eventually cell death. This histone deacetylase inhibitor-sensitive checkpoint appears to be distinct from G2/M checkpoints activated by genotoxins and microtubule poisons and may be the human homologue of a yeast G2 checkpoint, which responds to aberrant histone acetylation states. Azelaic bishydroxamic acid may represent a new class of anticancer drugs with selective toxicity based on its ability to target a dysfunctional checkpoint mechanism in tumor cells.

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DNA damage checkpoint kinases in cancer

Expert Reviews in Molecular Medicine ◽

10.1017/erm.2020.3 ◽

2020 ◽

Vol 22 ◽

Cited By ~ 7

Author(s):

Hannah L. Smith ◽

Harriet Southgate ◽

Deborah A. Tweddle ◽

Nicola J. Curtin

Keyword(s):

Cell Cycle ◽

Dna Damage ◽

Environmental Dna ◽

Cell Cycle Checkpoint ◽

Checkpoint Control ◽

Integrated Network ◽

Checkpoint Kinases ◽

G1 Checkpoint ◽

Cycle Checkpoint ◽

High Level

Abstract DNA damage response (DDR) pathway prevents high level endogenous and environmental DNA damage being replicated and passed on to the next generation of cells via an orchestrated and integrated network of cell cycle checkpoint signalling and DNA repair pathways. Depending on the type of damage, and where in the cell cycle it occurs different pathways are involved, with the ATM-CHK2-p53 pathway controlling the G1 checkpoint or ATR-CHK1-Wee1 pathway controlling the S and G2/M checkpoints. Loss of G1 checkpoint control is common in cancer through TP53, ATM mutations, Rb loss or cyclin E overexpression, providing a stronger rationale for targeting the S/G2 checkpoints. This review will focus on the ATM-CHK2-p53-p21 pathway and the ATR-CHK1-WEE1 pathway and ongoing efforts to target these pathways for patient benefit.

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