scholarly journals MYBL2-Driven Transcriptional Programs Link Replication Stress and Error-prone DNA Repair With Genomic Instability in Lung Adenocarcinoma

2021 ◽  
Vol 10 ◽  
Author(s):  
Benjamin B. Morris ◽  
Nolan A. Wages ◽  
Patrick A. Grant ◽  
P. Todd Stukenberg ◽  
Ryan D. Gentzler ◽  
...  
Keyword(s):  
Cell Cycle ◽  
Dna Damage ◽  
Dna Repair ◽  
Transcription Factor ◽  
Lung Adenocarcinoma ◽  
Genomic Instability ◽  
Replication Stress ◽  
Omics Data ◽  
Repair Pathways ◽  
Lung Adenocarcinomas

It has long been recognized that defects in cell cycle checkpoint and DNA repair pathways give rise to genomic instability, tumor heterogeneity, and metastasis. Despite this knowledge, the transcription factor-mediated gene expression programs that enable survival and proliferation in the face of enormous replication stress and DNA damage have remained elusive. Using robust omics data from two independent studies, we provide evidence that a large cohort of lung adenocarcinomas exhibit significant genome instability and overexpress the DNA damage responsive transcription factor MYB proto-oncogene like 2 (MYBL2). Across two studies, elevated MYBL2 expression was a robust marker of poor overall survival and disease-free survival outcomes, regardless of disease stage. Clinically, elevated MYBL2 expression identified patients with aggressive early onset disease, increased lymph node involvement, and increased incidence of distant metastases. Analysis of genomic sequencing data demonstrated that MYBL2 High lung adenocarcinomas had elevated somatic mutation burden, widespread chromosomal alterations, and alterations in single-strand DNA break repair pathways. In this study, we provide evidence that impaired single-strand break repair, combined with a loss of cell cycle regulators TP53 and RB1, give rise to MYBL2-mediated transcriptional programs. Omics data supports a model wherein tumors with significant genomic instability upregulate MYBL2 to drive genes that control replication stress responses, promote error-prone DNA repair, and antagonize faithful homologous recombination repair. Our study supports the use of checkpoint kinase 1 (CHK1) pharmacological inhibitors, in targeted MYBL2 High patient cohorts, as a future therapy to improve lung adenocarcinoma patient outcomes.

scholarly journals Mechanisms of Genome Maintenance in Plants: Playing It Safe With Breaks and Bumps

2021 ◽  
Vol 12 ◽  
Author(s):  
Aamir Raina ◽  
Parmeshwar K. Sahu ◽  
Rafiul Amin Laskar ◽  
Nitika Rajora ◽  
Richa Sao ◽  
...  
Keyword(s):  
Dna Damage ◽  
Dna Repair ◽  
Plant Growth ◽  
Genomic Instability ◽  
Model Organisms ◽  
Ultraviolet Rays ◽  
Genomic Integrity ◽  
Wide Range ◽  
Repair Pathways ◽  
Living Organisms

Maintenance of genomic integrity is critical for the perpetuation of all forms of life including humans. Living organisms are constantly exposed to stress from internal metabolic processes and external environmental sources causing damage to the DNA, thereby promoting genomic instability. To counter the deleterious effects of genomic instability, organisms have evolved general and specific DNA damage repair (DDR) pathways that act either independently or mutually to repair the DNA damage. The mechanisms by which various DNA repair pathways are activated have been fairly investigated in model organisms including bacteria, fungi, and mammals; however, very little is known regarding how plants sense and repair DNA damage. Plants being sessile are innately exposed to a wide range of DNA-damaging agents both from biotic and abiotic sources such as ultraviolet rays or metabolic by-products. To escape their harmful effects, plants also harbor highly conserved DDR pathways that share several components with the DDR machinery of other organisms. Maintenance of genomic integrity is key for plant survival due to lack of reserve germline as the derivation of the new plant occurs from the meristem. Untowardly, the accumulation of mutations in the meristem will result in a wide range of genetic abnormalities in new plants affecting plant growth development and crop yield. In this review, we will discuss various DNA repair pathways in plants and describe how the deficiency of each repair pathway affects plant growth and development.

Inducible Loss of the Fanconi Anemia Pathway in iPSC Causes Rapid Cell Cycle Arrest and Apoptosis through ATM/ATR and p53 Signaling

Blood ◽  
2014 ◽  
Vol 124 (21) ◽  
pp. 3528-3528
Author(s):  
Timothy M Chlon ◽  
Elizabeth E Hoskins ◽  
Sonya Ruiz-Torres ◽  
Christopher N Mayhew ◽  
Kathryn A Wikenheiser-Brokamp ◽  
...  
Keyword(s):  
Cell Cycle ◽  
Stem Cells ◽  
Bone Marrow ◽  
Dna Damage ◽  
Cell Death ◽  
Dna Repair ◽  
Cell Cycle Arrest ◽  
Loss Of Function ◽  
Cycle Arrest ◽  
Repair Pathways

Abstract As the source of all cells in the developing embryo proper, embryonic stem cells (ESC) bear the unique responsibility to prevent mutations from being propagated throughout the entire organism and the germ line. It is likely for this reason that ESC and induced pluripotent stem cells (iPSC) maintain a dramatically lower mutation frequency than cultured somatic cells. Multiple mechanisms for this enhanced genomic surveillance have been proposed, including hypersensitivity of DNA damage response signaling pathways and increased activity of error-free DNA repair pathways, such as homologous recombination. However, the effect of loss of function of DNA repair pathways in these cells remains poorly understood. The Fanconi Anemia (FA) pathway is a DNA repair pathway that is required for the repair of DNA interstrand crosslink damage and also promotes repair of DNA double-strand breaks by homologous recombination . Genetic defects in this pathway cause a disease characterized by bone marrow failure and extreme cancer incidence. Several recent studies have revealed that the FA pathway is required for efficient somatic cell reprogramming to iPSC and suggest that FA cells undergo cell death during this process. Another recent study found that the growth of FA patient-specific iPSC was attenuated with a G2/M arrest when compared to control iPSC, suggesting that these cells arrest upon failed DNA repair. In this study, we sought to determine the effects of acute loss of function of the FA pathway in iPSC through the generation of FA patient-derived iPSC with inducible complementation of the defective FA gene. Fibroblasts were cultured from skin biopsies of multiple FA patients and transduced with a lentiviral vector expressing the complementing FA gene product under DOX-inducible control. Cells were then reprogrammed to iPSC using episomal transfection. These cells formed iPSC colonies only when reprogramming was carried out in the presence of DOX, confirming that the FA pathway is required for efficient reprogramming. Once cell lines were obtained, DOX-dependent FA functionality was verified based on FANCD2 monoubiquitination and nuclear focus formation after treatment with DNA damaging agents. We then cultured the iPSC for extended periods of time in the presence and absence of DOX. Interestingly, the cultures underwent profound cell death and cell cycle arrest within 7 days of DOX-withdrawal and completely failed to expand after one passage. EdU cell cycle analysis confirmed cell cycle arrest in the G2/M phase. Furthermore, cleaved caspase 3 staining confirmed that the number of apoptotic cells increased by 3-fold in the -DOX culture. Despite these effects, cells cultured in both the presence and absence of DOX formed teratomas in nude mice, thus indicating the maintenance of full differentiation capacity in the absence of the FA pathway. In order to determine the mechanisms underlying G2/M arrest and cell death, expression of p53 and its target genes was detected by both western blot analysis and qRT-PCR. Only a slight increase in p53 activation was observed by 7 days post DOX-withdrawal. Furthermore, knockdown of p53 resulted in rescue from apoptosis to normal levels but not rescue from cell cycle arrest. Increased ATM and ATR DNA damage sensor kinase activities were also detected in –DOX cells, concominant with increased phosphorylation of the ATM-target Chk2 and reduced abundance of the G2/M checkpoint protein CDC25A. These results reveal hyperactive DNA damage responses upon FA loss which may underlie the attenuated cell cycle progression of FA-iPSC independent of p53. Remarkably, effects in this FA model system appear equivalent to those responsible for the depletion of HSC in the bone marrow of FA patients. Thus, iPSC models may be useful for future studies of the mechanisms underlying FA stem cell arrest and for the development of therapeutics that alleviate these phenotypes. Disclosures No relevant conflicts of interest to declare.

scholarly journals Impact of Replication Stress in Human Papillomavirus Pathogenesis

2018 ◽  
Vol 93 (2) ◽  
Author(s):  
Cary A. Moody
Keyword(s):  
Cell Cycle ◽  
Dna Damage ◽  
Human Papillomavirus ◽  
Genomic Instability ◽  
Viral Persistence ◽  
Replication Stress ◽  
Cell Cycle Checkpoints ◽  
Premalignant Lesions ◽  
Associated Lesions ◽  
Novel Approach

ABSTRACTThe inactivation of critical cell cycle checkpoints by the human papillomavirus (HPV) oncoprotein E7 results in replication stress (RS) that leads to genomic instability in premalignant lesions. Intriguingly, RS tolerance is achieved through several mechanisms, enabling HPV to exploit the cellular RS response for viral replication and to facilitate viral persistence in the presence of DNA damage. As such, inhibitors of the RS response pathway may provide a novel approach to target HPV-associated lesions and cancers.

scholarly journals Inhibition of DNA Repair in Cancer Therapy: Toward a Multi-Target Approach

2020 ◽  
Vol 21 (18) ◽  
pp. 6684
Author(s):  
Samuele Lodovichi ◽  
Tiziana Cervelli ◽  
Achille Pellicioli ◽  
Alvaro Galli
Keyword(s):  
Cell Cycle ◽  
Dna Damage ◽  
Dna Repair ◽  
Cancer Therapy ◽  
Clinical Outcome ◽  
Cancer Cells ◽  
Cell Cycle Checkpoint ◽  
Normal Cells ◽  
Cycle Checkpoint ◽  
Repair Pathways

Alterations in DNA repair pathways are one of the main drivers of cancer insurgence. Nevertheless, cancer cells are more susceptible to DNA damage than normal cells and they rely on specific functional repair pathways to survive. Thanks to advances in genome sequencing, we now have a better idea of which genes are mutated in specific cancers and this prompted the development of inhibitors targeting DNA repair players involved in pathways essential for cancer cells survival. Currently, the pivotal concept is that combining the inhibition of mechanisms on which cancer cells viability depends is the most promising way to treat tumorigenesis. Numerous inhibitors have been developed and for many of them, efficacy has been demonstrated either alone or in combination with chemo or radiotherapy. In this review, we will analyze the principal pathways involved in cell cycle checkpoint and DNA repair focusing on how their alterations could predispose to cancer, then we will explore the inhibitors developed or in development specifically targeting different proteins involved in each pathway, underscoring the rationale behind their usage and how their combination and/or exploitation as adjuvants to classic therapies could help in patients clinical outcome.

scholarly journals PLEK2 Gene Upregulation Might Independently Predict Shorter Progression-Free Survival in Lung Adenocarcinoma

2020 ◽  
Vol 19 ◽  
pp. 153303382095703
Author(s):  
Wenqian Zhang ◽  
Tong Li ◽  
Bin Hu ◽  
Hui Li
Keyword(s):  
Cell Cycle ◽  
Dna Damage ◽  
Dna Repair ◽  
Lung Adenocarcinoma ◽  
Single Cell ◽  
Prognostic Value ◽  
Progression Free Survival ◽  
Single Cell Level ◽  
Cell Level ◽  
Free Survival

Objective: This study aimed to explore PLEK2 expression profile, its prognostic value, and the potential genomic alterations associated with its dysregulation in lung adenocarcinoma (LUAD) and lung squamous cell carcinoma (LUSC). Materials and methods: Data from The Cancer Genome Atlas (TCGA), The Genotype-Tissue Expression (GTEx), and Kaplan-Meier plotter were used in combination for bioinformatic analysis. Results: PLEK2 mRNA was significantly upregulated in both LUAD and LUSC compared with their respective normal controls. PLEK2 upregulation showed independent prognostic value in progression-free survival (PFS) (HR: 1.169, 95%CI: 1.033 -1.322, p = 0.014). PLEK2 mRNA expression was positively correlated with invasion, cell cycle, DNA damage, and DNA repair of LUAD cells at the single-cell level. Genomic analysis showed that gene-level amplification might not directly lead to increased PLEK2 expression. Methylation profile analysis found 4 CpG sites (cg12199376, cg14437634, cg17641252, and cg06724236) had at least a weakly negative correlation with PLEK2 expression, among which cg12199376, cg14437634 and cg17641252 locate around the first exon of the gene. Conclusions: Increased PLEK2 expression might be a specific prognostic biomarker of poor PFS in LUAD patients. Its expression had significant positive correlations with invasion, cell cycle, DNA damage, and DNA repair of LUAD cells at the single-cell level. Promoter hypomethylation might be a potential mechanism leading to its upregulation.

scholarly journals The Interactions of DNA Repair, Telomere Homeostasis, and p53 Mutational Status in Solid Cancers: Risk, Prognosis, and Prediction

Cancers ◽  
2021 ◽  
Vol 13 (3) ◽  
pp. 479
Author(s):  
Pavel Vodicka ◽  
Ladislav Andera ◽  
Alena Opattova ◽  
Ludmila Vodickova
Keyword(s):  
Cell Cycle ◽  
Dna Damage ◽  
Dna Repair ◽  
Dna Lesions ◽  
Cell Cycle Checkpoint ◽  
Solid Cancer ◽  
Genomic Integrity ◽  
Repair Capacity ◽  
Mutational Status ◽  
Telomere Homeostasis

The disruption of genomic integrity due to the accumulation of various kinds of DNA damage, deficient DNA repair capacity, and telomere shortening constitute the hallmarks of malignant diseases. DNA damage response (DDR) is a signaling network to process DNA damage with importance for both cancer development and chemotherapy outcome. DDR represents the complex events that detect DNA lesions and activate signaling networks (cell cycle checkpoint induction, DNA repair, and induction of cell death). TP53, the guardian of the genome, governs the cell response, resulting in cell cycle arrest, DNA damage repair, apoptosis, and senescence. The mutational status of TP53 has an impact on DDR, and somatic mutations in this gene represent one of the critical events in human carcinogenesis. Telomere dysfunction in cells that lack p53-mediated surveillance of genomic integrity along with the involvement of DNA repair in telomeric DNA regions leads to genomic instability. While the role of individual players (DDR, telomere homeostasis, and TP53) in human cancers has attracted attention for some time, there is insufficient understanding of the interactions between these pathways. Since solid cancer is a complex and multifactorial disease with considerable inter- and intra-tumor heterogeneity, we mainly dedicated this review to the interactions of DNA repair, telomere homeostasis, and TP53 mutational status, in relation to (a) cancer risk, (b) cancer progression, and (c) cancer therapy.

scholarly journals SOG1 transcription factor promotes the onset of endoreduplication under salinity stress in Arabidopsis

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Kalyan Mahapatra ◽  
Sujit Roy
Keyword(s):  
Cell Cycle ◽  
Dna Damage ◽  
Cell Death ◽  
Transcription Factor ◽  
Programmed Cell Death ◽  
Salinity Stress ◽  
Crucial Role ◽  
Genome Stability ◽  
Cell Cycle Checkpoint ◽  
Cell Cycle Regulators

AbstractAs like in mammalian system, the DNA damage responsive cell cycle checkpoint functions play crucial role for maintenance of genome stability in plants through repairing of damages in DNA and induction of programmed cell death or endoreduplication by extensive regulation of progression of cell cycle. ATM and ATR (ATAXIA-TELANGIECTASIA-MUTATED and -RAD3-RELATED) function as sensor kinases and play key role in the transmission of DNA damage signals to the downstream components of cell cycle regulatory network. The plant-specific NAC domain family transcription factor SOG1 (SUPPRESSOR OF GAMMA RESPONSE 1) plays crucial role in transducing signals from both ATM and ATR in presence of double strand breaks (DSBs) in the genome and found to play crucial role in the regulation of key genes involved in cell cycle progression, DNA damage repair, endoreduplication and programmed cell death. Here we report that Arabidopsis exposed to high salinity shows generation of oxidative stress induced DSBs along with the concomitant induction of endoreduplication, displaying increased cell size and DNA ploidy level without any change in chromosome number. These responses were significantly prominent in SOG1 overexpression line than wild-type Arabidopsis, while sog1 mutant lines showed much compromised induction of endoreduplication under salinity stress. We have found that both ATM-SOG1 and ATR-SOG1 pathways are involved in the salinity mediated induction of endoreduplication. SOG1was found to promote G2-M phase arrest in Arabidopsis under salinity stress by downregulating the expression of the key cell cycle regulators, including CDKB1;1, CDKB2;1, and CYCB1;1, while upregulating the expression of WEE1 kinase, CCS52A and E2Fa, which act as important regulators for induction of endoreduplication. Our results suggest that Arabidopsis undergoes endoreduplicative cycle in response to salinity induced DSBs, showcasing an adaptive response in plants under salinity stress.

scholarly journals Targeting DNA Replication Stress and DNA Double-Strand Break Repair for Optimizing SCLC Treatment

Cancers ◽  
2019 ◽  
Vol 11 (9) ◽  
pp. 1289 ◽  
Author(s):  
Xing Bian ◽  
Wenchu Lin
Keyword(s):  
Lung Cancer ◽  
Dna Damage ◽  
Dna Replication ◽  
Dna Damage Repair ◽  
Predictive Biomarkers ◽  
Replication Stress ◽  
Genotoxic Stress ◽  
Repair System ◽  
Damage Repair ◽  
Repair Pathways

Small cell lung cancer (SCLC), accounting for about 15% of all cases of lung cancer worldwide, is the most lethal form of lung cancer. Despite an initially high response rate of SCLC to standard treatment, almost all patients are invariably relapsed within one year. Effective therapeutic strategies are urgently needed to improve clinical outcomes. Replication stress is a hallmark of SCLC due to several intrinsic factors. As a consequence, constitutive activation of the replication stress response (RSR) pathway and DNA damage repair system is involved in counteracting this genotoxic stress. Therefore, therapeutic targeting of such RSR and DNA damage repair pathways will be likely to kill SCLC cells preferentially and may be exploited in improving chemotherapeutic efficiency through interfering with DNA replication to exert their functions. Here, we summarize potentially valuable targets involved in the RSR and DNA damage repair pathways, rationales for targeting them in SCLC treatment and ongoing clinical trials, as well as possible predictive biomarkers for patient selection in the management of SCLC.

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