scholarly journals Aneuploidy and deregulated DNA damage response define haploinsufficiency in breast tissues of BRCA2 mutation carriers

2019 ◽  
Author(s):  
Mihriban Karaayvaz ◽  
Rebecca E Silberman ◽  
Adam Langenbucher ◽  
Srinivas Vinod Saladi ◽  
Kenneth N Ross ◽  
...  
Keyword(s):  
Dna Damage ◽  
Brca2 Mutation ◽  
Copy Number Variations ◽  
Cancer Risk Assessment ◽  
Replication Checkpoint ◽  
Mutation Carriers ◽  
Risk Patients ◽  
Breast Tissues ◽  
Lp Cells

AbstractWomen harboring heterozygous germline mutations of BRCA2 have a 50-80% risk of developing breast cancer, yet the early pathogenesis of these cancers is poorly understood. We sought to reveal early steps in BRCA2-associated carcinogenesis through analysis of sorted cell populations from freshly-isolated, non-cancerous breast tissues among a cohort of BRCA2 mutation carriers and matched controls. Single-cell whole-genome sequencing demonstrates that >25% of BRCA2 carrier (BRCA2mut/+) luminal progenitor (LP) cells exhibit sub-chromosomal copy number variations (CNVs), which are rarely observed in non-carriers. Correspondingly, primary BRCA2mut/+ breast epithelia exhibit spontaneous and replication stress-induced DNA damage together with attenuated replication checkpoint and apoptotic responses, associated with an age-associated expansion of the LP compartment in human carrier tissues. These phenotypes are not associated with loss of wild-type BRCA2. Collectively, these findings provide evidence for BRCA2 haploinsufficiency and associated DNA damage in vivo that precede histologic abnormalities. These results provide unanticipated opportunities for new cancer risk assessment and prevention strategies in high-risk patients.

scholarly journals Aneuploidy and a deregulated DNA damage response suggest haploinsufficiency in breast tissues of BRCA2 mutation carriers

2020 ◽  
Vol 6 (5) ◽  
pp. eaay2611 ◽  
Author(s):  
Mihriban Karaayvaz-Yildirim ◽  
Rebecca E. Silberman ◽  
Adam Langenbucher ◽  
Srinivas Vinod Saladi ◽  
Kenneth N. Ross ◽  
...  
Keyword(s):  
Dna Damage ◽  
Brca2 Mutation ◽  
Copy Number Variations ◽  
Replication Checkpoint ◽  
Mutation Carriers ◽  
Damage Response ◽  
Risk Patients ◽  
Breast Tissues ◽  
Lp Cells

Women harboring heterozygous germline mutations of BRCA2 have a 50 to 80% risk of developing breast cancer, yet the pathogenesis of these cancers is poorly understood. To reveal early steps in BRCA2-associated carcinogenesis, we analyzed sorted cell populations from freshly-isolated, non-cancerous breast tissues of BRCA2 mutation carriers and matched controls. Single-cell whole-genome sequencing demonstrates that >25% of BRCA2 carrier (BRCA2mut/+) luminal progenitor (LP) cells exhibit sub-chromosomal copy number variations, which are rarely observed in non-carriers. Correspondingly, primary BRCA2mut/+ breast epithelia exhibit DNA damage together with attenuated replication checkpoint and apoptotic responses, and an age-associated expansion of the LP compartment. We provide evidence that these phenotypes do not require loss of the wild-type BRCA2 allele. Collectively, our findings suggest that BRCA2 haploinsufficiency and associated DNA damage precede histologic abnormalities in vivo. Using these hallmarks of cancer predisposition will yield unanticipated opportunities for improved risk assessment and prevention strategies in high-risk patients.

scholarly journals Pie1, a Protein Interacting with Mec1, Controls Cell Growth and Checkpoint Responses in Saccharomyces cerevisiae

2001 ◽  
Vol 21 (3) ◽  
pp. 755-764 ◽  
Author(s):  
Tatsushi Wakayama ◽  
Tae Kondo ◽  
Seiko Ando ◽  
Kunihiro Matsumoto ◽  
Katsunori Sugimoto
Keyword(s):  
Dna Damage ◽  
Cell Growth ◽  
Kinase Activity ◽  
Critical Role ◽  
Kinase Domain ◽  
Protein Kinase Activity ◽  
Replication Checkpoint ◽  
Family Protein ◽  
Replication Block

ABSTRACT In eukaryotes, the ATM and ATR family proteins play a critical role in the DNA damage and replication checkpoint controls. These proteins are characterized by a kinase domain related to the phosphatidylinositol 3-kinase, but they have the ability to phosphorylate proteins. In budding yeast, the ATR family protein Mec1/Esr1 is essential for checkpoint responses and cell growth. We have isolated the PIE1 gene in a two-hybrid screen for proteins that interact with Mec1, and we show that Pie1 interacts physically with Mec1 in vivo. Like MEC1, PIE1is essential for cell growth, and deletion of the PIE1 gene causes defects in the DNA damage and replication block checkpoints similar to those observed in mec1Δ mutants. Rad53 hyperphosphorylation following DNA damage and replication block is also decreased in pie1Δ cells, as in mec1Δcells. Pie1 has a limited homology to fission yeast Rad26, which forms a complex with the ATR family protein Rad3. Mutation of the region in Pie1 homologous to Rad26 results in a phenotype similar to that of thepie1Δ mutation. Mec1 protein kinase activity appears to be essential for checkpoint responses and cell growth. However, Mec1 kinase activity is unaffected by the pie1Δ mutation, suggesting that Pie1 regulates some essential function other than Mec1 kinase activity. Thus, Pie1 is structurally and functionally related to Rad26 and interacts with Mec1 to control checkpoints and cell proliferation.

scholarly journals Genetic variation in the NEIL2 DNA glycosylase gene is associated with oxidative DNA damage in BRCA2 mutation carriers

Oncotarget ◽  
2017 ◽  
Vol 8 (70) ◽  
pp. 114626-114636 ◽  
Author(s):  
Carlos Benítez-Buelga ◽  
Juan Miguel Baquero ◽  
Tereza Vaclova ◽  
Victoria Fernández ◽  
Paloma Martín ◽  
...  
Keyword(s):  
Dna Damage ◽  
Genetic Variation ◽  
Oxidative Dna Damage ◽  
Brca2 Mutation ◽  
Dna Glycosylase ◽  
Mutation Carriers

scholarly journals Characteristics of breast cancer in BRCA1/BRCA2 mutation carriers and non-carriersfrom a genetic counseling unit in Croatia

2020 ◽  
Vol 48 (2-3) ◽  
pp. 54-60
Author(s):  
Snježana Ramić ◽  
◽  
Gabriela Alfier ◽  
Iva Kirac ◽  
Ivan Milas ◽  
...  
Keyword(s):  
Breast Cancer ◽  
Family History ◽  
Brca2 Mutation ◽  
Significant Risk ◽  
Brca2 Gene ◽  
Cancer Risk Assessment ◽  
Luminal B ◽  
Mutation Carriers ◽  
Breast Cancer Risk Assessment ◽  
Brca1 Brca2

Breast cancer (BC) represents 25% of all malignancies in Croatian women, and in 18.8% of cases, it is diagnosed before the age of 50. Croatia launched BRCA testing of people at increased family risk. Hereditary BC is mainly caused by a pathogenic mutation in the BRCA1 or BRCA2 gene and is a significant risk factor for developing breast and ovarian cancer. The present study included 127 women diagnosed with BC, with a strong family history of BC and the known status of the germline mutations in the BRCA1/BRCA2 genes. The majority of women were BRCA1/2 mutation non-carriers, while 15.7% were BRCA1/2 mutation carriers, and 4% had a variant of unknown significance (VUS). BRCA1/2 mutation carriers were younger than non-carriers (median 38.5 years vs. 44 years) (P=.01) and had tumors of higher histological grade (P<.001). The intrinsic subtype of BC differs significantly depending on the type of mutation (P<.001). Triple-negative BC prevailed (87.5%) in BRCA1 mutation carriers, and 12.5% had a luminal B/HER2-negative BC. Four patients were BRCA2 mutation carriers, and two of them had luminal B/HER2-positive BC. Most BRCA1/2 non-carriers (69.2%) and all VUS-carriers have luminal B/HER2-negative BC. Our results show that BRCA1/2 mutation testing is essential for women with a family history burden. It is a piece of valuable information in breast cancer risk assessment and contributes to early diagnosis.

Abstract 18789: BRCA2 is a Novel Regulator of Endothelial Cell Function and Apoptosis Following Hyperglycemia

Circulation ◽  
2015 ◽  
Vol 132 (suppl_3) ◽  
Author(s):  
Pratiek N Matkar ◽  
Mohammed Al-Omran ◽  
Subodh Verma ◽  
Howard Leong-Poi ◽  
Krishna K Singh
Keyword(s):  
Breast Cancer ◽  
Dna Damage ◽  
Endothelial Dysfunction ◽  
Brca2 Mutation ◽  
No Production ◽  
Ros Production ◽  
Endothelial Cell Function ◽  
Protein Levels ◽  
Mutation Carriers

Background: Germ-line mutations in the tumor suppressor gene BRCA2 (breast cancer 2, early onset) predispose carriers mostly to breast cancer, and BRCA2 mutation carriers also face a 2-fold increase in the risk of developing diabetes.Hyperglycemia, the hallmark of diabetes, is a major risk factor for endothelial dysfunction leading to vascular complications. The relationship linking role of BRCA2 in the development of diabetes and endothelial dysfunction remains mainly unexplored. Methods: To elucidate the role of BRCA2 in diabetes and endothelial apoptosis/dysfunction in vitro, we silenced BRCA2 in human umbilical vein endothelial cells (ECs) and evaluated the markers of EC function and apoptosis following hyperglycemia. Results: We first confirmed the basal expression of BRCA2 in ECs at transcript and protein levels by qPCR and immunoblotting, respectively. Interestingly, hyperglycemia significantly induced BRCA2 expression after 48 hours of treatment. We then silenced BRCA2 in ECs and confirmed successful silencing at transcript and protein levels. Hyperglycemia significantly increased the reactive oxygen species (ROS) production in the BRCA2-deficient ECs in comparison to control ECs. Increased ROS production was associated with exacerbated DNA-damage in BRCA2-silenced ECs as evidenced by increased expression and activation of DNA double-stranded breaks (DSBs) marker H2A.X and reduced RAD51-foci formation, an essential regulator of DSB repair. Increased DSBs were associated with significantly increased activation of p53. Elevated levels of DNA-damage and activated-p53 were further associated with significantly increased hyperglycemia-induced apoptosis in BRCA2-silenced ECs as measured by immunoblotting for cleaved-caspase-3, Bax and by TUNEL-staining.Key indices of endothelial function, including tube formation and NO production, were significantly reduced following hyperglycemia-treatment in BRCA2-deficient ECs. Conclusion: Our data for the first time, show an entirely novel role of BRCA2 as a regulator of endothelium in the setting of hyperglycemia, and provide important clues regarding the potential susceptibility of BRCA2 mutation carriers to hyperglycemia-induced cardiovascular complications.

scholarly journals A DNA Damage-Regulated BRCT-Containing Protein, TopBP1, Is Required for Cell Survival

2002 ◽  
Vol 22 (2) ◽  
pp. 555-566 ◽  
Author(s):  
Kazuhiko Yamane ◽  
Xianglin Wu ◽  
Junjie Chen
Keyword(s):  
Dna Damage ◽  
Cell Survival ◽  
Ataxia Telangiectasia ◽  
Topoisomerase Ii ◽  
Sequence Similarity ◽  
Dna Double Strand Breaks ◽  
Focus Formation ◽  
Replication Checkpoint ◽  
Strand Breaks

ABSTRACT BRCA1 carboxyl-terminal (BRCT) motifs are present in a number of proteins involved in DNA repair and/or DNA damage-signaling pathways. Human DNA topoisomerase II binding protein 1 (TopBP1) contains eight BRCT motifs and shares sequence similarity with the fission yeast Rad4/Cut5 protein and the budding yeast DPB11 protein, both of which are required for DNA damage and/or replication checkpoint controls. We report here that TopBP1 is phosphorylated in response to DNA double-strand breaks and replication blocks. TopBP1 forms nuclear foci and localizes to the sites of DNA damage or the arrested replication forks. In response to DNA strand breaks, TopBP1 phosphorylation depends on the ataxia telangiectasia mutated protein (ATM) in vivo. However, ATM-dependent phosphorylation of TopBP1 does not appear to be required for focus formation following DNA damage. Instead, focus formation relies on one of the BRCT motifs, BRCT5, in TopBP1. Antisense Morpholino oligomers against TopBP1 greatly reduced TopBP1 expression in vivo. Similar to that of ataxia telangiectasia-related protein (ATR), Chk1, or Hus1, downregulation of TopBP1 leads to reduced cell survival, probably due to increased apoptosis. Taken together, the data presented here suggest that, like its putative counterparts in yeast species, TopBP1 may be involved in DNA damage and replication checkpoint controls.

Curcumin-containing Silver Nanoparticles prevent carbon tetrachlorideinduced hepatotoxicity in mice

2020 ◽  
Vol 23 ◽  
Author(s):  
Hossam Ebaid ◽  
Mohamed Habila ◽  
Iftekhar Hassan ◽  
Jameel Al-Tamimi ◽  
Mohamed S. Omar ◽  
...  
Keyword(s):  
Dna Damage ◽  
Silver Nanoparticles ◽  
Nuclear Dna ◽  
Liquid Paraffin ◽  
Tail Length ◽  
Hepatic Tissue ◽  
Tissue Destruction ◽  
Group 2 ◽  
The Impact

Background: Hepatotoxicity remains an important clinical challenge. Hepatotoxicity observed in response to toxins and hazardous chemicals may be alleviated by delivery of the curcumin in silver nanoparticles (AgNPs-curcumin). In this study, we examined the impact of AgNPs-curcumin in a mouse model of carbon tetrachloride (CCl4)-induced hepatic injury. Methods: Male C57BL/6 mice were divided into three groups (n=8 per group). Mice in group 1 were treated with vehicle control alone, while mice in Group 2 received a single intraperitoneal injection of 1 ml/kg CCl4 in liquid paraffin (1:1 v/v). Mice in group 3 were treated with 2.5 mg/kg AgNPs-curcumin twice per week for three weeks after the CCl4 challenge. Results: Administration of CCL4 resulted in oxidative dysregulation, including significant reductions in reduced glutathione and concomitant elevations in the level of malondialdehyde (MDA). CCL4 challenge also resulted in elevated levels of serum aspartate transaminase (AST) and alanine transaminase (ALT); these findings were associated with the destruction of hepatic tissues. Treatment with AgNPs-curcumin prevented oxidative imbalance, hepatic dysfunction, and tissue destruction. A comet assay revealed that CCl4 challenge resulted in significant DNA damage as documented by a 70% increase in nuclear DNA tail-length; treatment with AgNPs-curcumin inhibited the CCL4-mediated increase in nuclear DNA tail-length by 34%. Conclusion: Administration of AgNPs-curcumin resulted in significant antioxidant activity in vivo. This agent has the potential to prevent the hepatic tissue destruction and DNA damage that results from direct exposure to CCL4.

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