Withanolide D Enhances Radiosensitivity of Human Cancer Cells by Inhibiting DNA Damage Non-homologous End Joining Repair Pathway

Abstract DNA polymerase theta (POLQ)-mediated end joining (TMEJ) is a distinct pathway for mediating DNA double-strand break (DSB) repair. TMEJ is required for the viability of BRCA-mutated cancer cells. It is crucial to identify tumors that rely on POLQ activity for DSB repair, because such tumors are defective in other DSB repair pathways and have predicted sensitivity to POLQ inhibition and to cancer therapies that produce DSBs. We define here the POLQ-associated mutation signatures in human cancers, characterized by short insertions and deletions in a specific range of microhomologies. By analyzing 82 COSMIC (Catalogue of Somatic Mutations in Cancer) signatures, we found that BRCA-mutated cancers with a higher level of POLQ expression have a greatly enhanced representation of the small insertion and deletion signature 6, as well as single base substitution signature 3. Using human cancer cells with disruptions of POLQ, we further show that TMEJ dominates end joining of two separated DSBs (distal EJ). Templated insertions with microhomology are enriched in POLQ-dependent distal EJ. The use of this signature analysis will aid in identifying tumors relying on POLQ activity.

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A role for the p53 tumour suppressor in regulating the balance between homologous recombination and non-homologous end joining

Open Biology ◽

10.1098/rsob.160225 ◽

2016 ◽

Vol 6 (9) ◽

pp. 160225 ◽

Cited By ~ 16

Author(s):

Sylvie Moureau ◽

Janna Luessing ◽

Emma Christina Harte ◽

Muriel Voisin ◽

Noel Francis Lowndes

Keyword(s):

Dna Damage ◽

Homologous Recombination ◽

Tumour Suppressor ◽

Cycle Phase ◽

Repair Pathway ◽

End Joining ◽

Dsb Repair ◽

Pathway Choice ◽

Non Homologous End Joining ◽

End Resection

Loss of p53, a transcription factor activated by cellular stress, is a frequent event in cancer. The role of p53 in tumour suppression is largely attributed to cell fate decisions. Here, we provide evidence supporting a novel role for p53 in the regulation of DNA double-strand break (DSB) repair pathway choice. 53BP1, another tumour suppressor, was initially identified as p53 Binding Protein 1, and has been shown to inhibit DNA end resection, thereby stimulating non-homologous end joining (NHEJ). Yet another tumour suppressor, BRCA1, reciprocally promotes end resection and homologous recombination (HR). Here, we show that in both human and mouse cells, the absence of p53 results in impaired 53BP1 focal recruitment to sites of DNA damage induced by ionizing radiation. This effect is largely independent of cell cycle phase and the extent of DNA damage. In p53-deficient cells, diminished localization of 53BP1 is accompanied by a reciprocal increase in BRCA1 recruitment to DSBs. Consistent with these findings, we demonstrate that DSB repair via NHEJ is abrogated, while repair via homology-directed repair (HDR) is stimulated. Overall, we propose that in addition to its role as an ‘effector’ protein in the DNA damage response, p53 plays a role in the regulation of DSB repair pathway choice.

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The Extract of Leonurus sibiricus Transgenic Roots with AtPAP1 Transcriptional Factor Induces Apoptosis via DNA Damage and Down Regulation of Selected Epigenetic Factors in Human Cancer Cells

Neurochemical Research ◽

10.1007/s11064-018-2551-6 ◽

2018 ◽

Vol 43 (7) ◽

pp. 1363-1370 ◽

Cited By ~ 5

Author(s):

Przemysław Sitarek ◽

Tomasz Kowalczyk ◽

Simona Santangelo ◽

Adam J. Białas ◽

Monika Toma ◽

...

Keyword(s):

Dna Damage ◽

Cancer Cells ◽

Human Cancer ◽

Transcriptional Factor ◽

Epigenetic Factors ◽

Down Regulation ◽

Transgenic Roots ◽

Human Cancer Cells ◽

Leonurus Sibiricus

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Differential response between the p53 ubiquitin–protein ligases Pirh2 and MdM2 following DNA damage in human cancer cells

Experimental Cell Research ◽

10.1016/j.yexcr.2006.07.005 ◽

2006 ◽

Vol 312 (17) ◽

pp. 3370-3378 ◽

Cited By ~ 22

Author(s):

Wenrui Duan ◽

Li Gao ◽

Xin Wu ◽

Yang Zhang ◽

Gregory A. Otterson ◽

...

Keyword(s):

Dna Damage ◽

Cancer Cells ◽

Human Cancer ◽

Differential Response ◽

Human Cancer Cells ◽

Protein Ligases

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Autophagy-Mediated Clearance of Free Genomic DNA in the Cytoplasm Protects the Growth and Survival of Cancer Cells

Frontiers in Oncology ◽

10.3389/fonc.2021.667920 ◽

2021 ◽

Vol 11 ◽

Author(s):

Mengfei Yao ◽

Yaqian Wu ◽

Yanan Cao ◽

Haijing Liu ◽

Ningning Ma ◽

...

Keyword(s):

Dna Damage ◽

Cancer Cells ◽

Genomic Dna ◽

Human Cancer ◽

Cancer Cell Line ◽

Growth And Survival ◽

Human Cancer Cells ◽

Cytoplasmic Dna ◽

Chemical Inhibitors ◽

Nuclear Damage

The cGAS (GMP-AMP synthase)-mediated senescence-associated secretory phenotype (SASP) and DNA-induced autophagy (DNA autophagy) have been extensively investigated in recent years. However, cGAS-mediated autophagy has not been elucidated in cancer cells. The described investigation revealed that active DNA autophagy but not SASP activity could be detected in the BT-549 breast cancer cell line with high micronucleus (MN) formation. DNA autophagy was identified as selective autophagy of free genomic DNA in the cytoplasm but not nucleophagy. The process of DNA autophagy in the cytosol could be initiate by cGAS and usually cooperates with SQSTM1-mediated autophagy of ubiquitinated histones. Cytoplasmic DNA, together with nuclear proteins such as histones, could be derived from DNA replication-induced nuclear damage and MN collapse. The inhibition of autophagy through chemical inhibitors as well as the genomic silencing of cGAS or SQSTM1 could suppress the growth and survival of cancer cells, and induced DNA damage could increase the sensitivity to these inhibitors. Furthermore, expanded observations of several other kinds of human cancer cells indicated that high relative DNA autophagy or enhancement of DNA damage could also increase or sensitize these cells to inhibition of DNA autophagy.

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The Anticancer Drug 3-Bromopyruvate Induces DNA Damage Potentially Through Reactive Oxygen Species in Yeast and in Human Cancer Cells

Cells ◽

10.3390/cells9051161 ◽

2020 ◽

Vol 9 (5) ◽

pp. 1161 ◽

Cited By ~ 2

Author(s):

Magdalena Cal ◽

Irwin Matyjaszczyk ◽

Ireneusz Litwin ◽

Daria Augustyniak ◽

Rafał Ogórek ◽

...

Keyword(s):

Reactive Oxygen Species ◽

Dna Damage ◽

Cancer Cells ◽

Human Cancer ◽

Reactive Oxygen ◽

Atp Depletion ◽

Mitochondrial Enzymes ◽

Oxygen Species ◽

Human Cancer Cells ◽

The Impact

3-bromopyruvate (3-BP) is a small molecule with anticancer and antimicrobial activities. 3-BP is taken up selectively by cancer cells’ mono-carboxylate transporters (MCTs), which are highly overexpressed by many cancers. When 3-BP enters cancer cells it inactivates several glycolytic and mitochondrial enzymes, leading to ATP depletion and the generation of reactive oxygen species. While mechanisms of 3-BP uptake and its influence on cell metabolism are well understood, the impact of 3-BP at certain concentrations on DNA integrity has never been investigated in detail. Here we have collected several lines of evidence suggesting that 3-BP induces DNA damage probably as a result of ROS generation, in both yeast and human cancer cells, when its concentration is sufficiently low and most cells are still viable. We also demonstrate that in yeast 3-BP treatment leads to generation of DNA double-strand breaks only in S-phase of the cell cycle, possibly as a result of oxidative DNA damage. This leads to DNA damage, checkpoint activation and focal accumulation of the DNA response proteins. Interestingly, in human cancer cells exposure to 3-BP also induces DNA breaks that trigger H2A.X phosphorylation. Our current data shed new light on the mechanisms by which a sufficiently low concentration of 3-BP can induce cytotoxicity at the DNA level, a finding that might be important for the future design of anticancer therapies.

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