scholarly journals Assessing BRCA1 activity in DNA damage repair using human induced pluripotent stem cells as an approach to assist classification of BRCA1 variants of uncertain significance

PLoS ONE ◽  
2021 ◽  
Vol 16 (12) ◽  
pp. e0260852
Author(s):  
Meryem Ozgencil ◽  
Julian Barwell ◽  
Marc Tischkowitz ◽  
Louise Izatt ◽  
Ian Kesterton ◽  
...  
Keyword(s):  
Dna Damage ◽  
Dna Damage Repair ◽  
Ips Cells ◽  
Variants Of Uncertain Significance ◽  
Cellular Models ◽  
Pathogenic Variants ◽  
Damage Repair ◽  
Uncertain Significance ◽  
Induced Pluripotent ◽  
The Impact

Establishing a universally applicable protocol to assess the impact of BRCA1 variants of uncertain significance (VUS) expression is a problem which has yet to be resolved despite major progresses have been made. The numerous difficulties which must be overcome include the choices of cellular models and functional assays. We hypothesised that the use of induced pluripotent stem (iPS) cells might facilitate the standardisation of protocols for classification, and could better model the disease process. We generated eight iPS cell lines from patient samples expressing either BRCA1 pathogenic variants, non-pathogenic variants, or BRCA1 VUSs. The impact of these variants on DNA damage repair was examined using a ɣH2AX foci formation assay, a Homologous Repair (HR) reporter assay, and a chromosome abnormality assay. Finally, all lines were tested for their ability to differentiate into mammary lineages in vitro. While the results obtained from the two BRCA1 pathogenic variants were consistent with published data, some other variants exhibited differences. The most striking of these was the BRCA1 variant Y856H (classified as benign), which was unexpectedly found to present a faulty HR repair pathway, a finding linked to the presence of an additional variant in the ATM gene. Finally, all lines were able to differentiate first into mammospheres, and then into more advanced mammary lineages expressing luminal- or basal-specific markers. This study stresses that BRCA1 genetic analysis alone is insufficient to establish a reliable and functional classification for assessment of clinical risk, and that it cannot be performed without considering the other genetic aberrations which may be present in patients. The study also provides promising opportunities for elucidating the physiopathology and clinical evolution of breast cancer, by using iPS cells.

scholarly journals Differentiation of Human Induced Pluripotent or Embryonic Stem Cells Decreases the DNA Damage Repair by Homologous Recombination

2017 ◽  
Vol 9 (5) ◽  
pp. 1660-1674 ◽  
Author(s):  
Kalpana Mujoo ◽  
Raj K. Pandita ◽  
Anjana Tiwari ◽  
Vijay Charaka ◽  
Sharmistha Chakraborty ◽  
...  
Keyword(s):  
Stem Cells ◽  
Dna Damage ◽  
Embryonic Stem Cells ◽  
Homologous Recombination ◽  
Dna Damage Repair ◽  
Embryonic Stem ◽  
Damage Repair ◽  
Induced Pluripotent

scholarly journals Persistent DNA Double-Strand Breaks After Repeated Diagnostic CT Scans in Breast Epithelial Cells and Lymphocytes

2021 ◽  
Vol 11 ◽  
Author(s):  
Natalia V. Bogdanova ◽  
Nina Jguburia ◽  
Dhanya Ramachandran ◽  
Nora Nischik ◽  
Katharina Stemwedel ◽  
...  
Keyword(s):  
Dna Damage ◽  
Dna Damage Repair ◽  
Cell Types ◽  
Strand Break ◽  
Ct Scans ◽  
Breast Epithelial Cell ◽  
Damage Repair ◽  
Breast Epithelial ◽  
The Impact ◽  
Diagnostic Ct

DNA double-strand break (DSB) induction and repair have been widely studied in radiation therapy (RT); however little is known about the impact of very low exposures from repeated computed tomography (CT) scans for the efficiency of repair. In our current study, DSB repair and kinetics were investigated in side-by-side comparison of RT treatment (2 Gy) with repeated diagnostic CT scans (≤20 mGy) in human breast epithelial cell lines and lymphoblastoid cells harboring different mutations in known DNA damage repair proteins. Immunocytochemical analysis of well known DSB markers γH2AX and 53BP1, within 48 h after each treatment, revealed highly correlated numbers of foci and similar appearance/disappearance profiles. The levels of γH2AX and 53BP1 foci after CT scans were up to 30% of those occurring 0.5 h after 2 Gy irradiation. The DNA damage repair after diagnostic CT scans was monitored and quantitatively assessed by both γH2AX and 53BP1 foci in different cell types. Subsequent diagnostic CT scans in 6 and/or 12 weeks intervals resulted in elevated background levels of repair foci, more pronounced in cells that were prone to genomic instability due to mutations in known regulators of DNA damage response (DDR). The levels of persistent foci remained enhanced for up to 6 months. This “memory effect” may reflect a radiation-induced long-term response of cells after low-dose x-ray exposure.

scholarly journals PARP inhibition in Ewing sarcoma: impact of germline DNA damage repair defects and activation of immunoregulatory pathways

2020 ◽  
Author(s):  
Lisa M. Maurer ◽  
Rosemarie E. Venier ◽  
Elina Mukherjee ◽  
Claire M. Julian ◽  
Jessica D. Daley ◽  
...  
Keyword(s):  
Dna Damage ◽  
Ewing Sarcoma ◽  
Immune Checkpoint ◽  
Dna Damage Repair ◽  
Germline Mutations ◽  
Parp Inhibition ◽  
Damage Repair ◽  
The Impact ◽  
Ewing Tumor

ABSTRACTEwing sarcoma, an oncofusion-driven primary bone tumor, can occur in the setting of various germline mutations in DNA damage repair pathway genes. We recently reported our discovery of a germline mutation in the DNA damage repair protein BARD1 (BRCA1-associated RING domain-1) in a patient with Ewing sarcoma. BARD1 is recruited to the site of DNA double stranded breaks via the poly(ADP-ribose) polymerase (PARP) protein and plays a critical role in DNA damage response pathways including homologous recombination. PARP inhibitors (PARPi) are effective against Ewing sarcoma cells in vitro, though have demonstrated limited success in clinical trials to date. In order to assess the impact of BARD1 loss on Ewing sarcoma sensitivity to PARP inhibitor therapy, we generated the novel PSaRC318 patient-derived Ewing tumor cell from our patient with a germline BARD1 mutation and then analyzed the response of these cells to PARPi. We demonstrate that PSaRC318 cells are sensitive to PARP inhibition and by testing the effect of BARD1 depletion in additional Ewing sarcoma cell lines, we confirm that loss of BARD1 enhances PARPi sensitivity. In certain malignancies, DNA damage can activate the IRF1 (interferon response factor 1) immunoregulatory pathway, and the activation of this pathway can drive immunosuppression through upregulation of the immune checkpoint protein PD-L1. In order to determine the ability of PARPi to alter Ewing tumor immunoregulation, we evaluated whether PARPi results in upregulation of the IRF1-PDL1 pathway. Indeed, we now demonstrate that PARPi leads to increased PD-L1 expression in Ewing sarcoma. Together, these data thus far suggest that while Ewing tumors harboring germline mutations in DNA damage repair proteins may in respond to PARPi in vitro, in vivo benefit of PARPi may only be demonstrated when counteracting the immunosuppressive effects of DNA damage by concurrently targeting immune checkpoint proteins.

scholarly journals Targeting BRCA and DNA Damage Repair Genes in GI Cancers: Pathophysiology and Clinical Perspectives

2021 ◽  
Vol 11 ◽  
Author(s):  
Kai Zimmer ◽  
Florian Kocher ◽  
Alberto Puccini ◽  
Andreas Seeber
Keyword(s):  
Dna Damage ◽  
Clinical Investigation ◽  
Dna Damage Repair ◽  
Cost Effective ◽  
Therapeutic Implications ◽  
Damage Repair ◽  
New Treatment ◽  
The Impact ◽  
Repair Genes ◽  
Breast Cancer Gene

Mutated germline alleles in the DNA damage repair (DDR) genes “breast cancer gene 1” (BRCA1) and BRCA2 have originally been identified as major susceptibility genes in breast and ovarian cancers. With the establishment and approval of more cost-effective gene sequencing methods, germline and somatic BRCA mutations have been detected in several cancers. Since the approval of poly (ADP)-ribose polymerase inhibitors (PARPi) for BRCA-mutated cancers, BRCA mutations gained rising therapeutic implications. The impact and significance of BRCA mutations have been evaluated extensively in the last decades. Moreover, other genes involved in the DDR pathway, such as ATM, ATR, or CHK1, have emerged as potential new treatment targets, as inhibitors of these proteins are currently under clinical investigation. This review gives a concise overview on the emerging clinical implications of mutations in the DDR genes in gastrointestinal cancers with a focus on BRCA mutations.

scholarly journals DNA Damage Repair Gene Mutations Are Indicative of a Favorable Prognosis in Colorectal Cancer Treated With Immune Checkpoint Inhibitors

2021 ◽  
Vol 10 ◽  
Author(s):  
Yipeng Song ◽  
Jian Huang ◽  
Dandan Liang ◽  
Ying Hu ◽  
Beibei Mao ◽  
...  
Keyword(s):  
Colorectal Cancer ◽  
Dna Damage ◽  
Immune Checkpoint ◽  
Immune Checkpoint Inhibitors ◽  
Checkpoint Inhibitors ◽  
Dna Damage Repair ◽  
Genomic Data ◽  
Cancer Center ◽  
Damage Repair ◽  
The Impact

BackgroundDNA damage repair (DDR) genes were recently implicated in the anti-tumor immune response. Therefore, it is worthwhile to unravel the implications of DDR pathways in the shaping of immune responsiveness in colorectal cancer (CRC) patients receiving immune checkpoint inhibitors (ICI).MethodsWe analyzed publicly available genomic data from a cohort treated with ICI from Memorial Sloan Kettering Cancer Center (MSK ICI cohort). To characterize the impact of the DDR mutation, the genomic data of The Cancer Genome Atlas (TCGA) colorectal adenocarcinoma (COADREAD) dataset was explored. We also analyzed the incidence of DDR mutation and microsatellite instability-high (MSI-H) in a Chinese CRC cohort using panel sequencing.ResultsThe DDR pathway was commonly mutated (21.8%) in the multicancer MSK ICI cohort, with the highest frequency of 36.4% in CRCs. Survival analysis showed that DDR mutation correlated with an improved overall survival (OS) in CRCs and pan-cancer in the MSK ICI cohort. However, no significant associations were identified in the TCGA COADREAD and MSK non-ICI CRCs. DDR mutation was associated with higher tumor mutational burden (TMB) levels and increased immune cell infiltration and immune checkpoint molecule expression in the TCGA COADREAD dataset. Last, we investigated the DDR mutational pattern and its associations with MSI-H and other genomic features in a Chinese CRC cohort. Notably, MSI-H and DDR mutation was present in 5.7% and 13.4% of cases, respectively, which suggests that DDR identifies a higher proportion of potential responders than MSI-H.ConclusionOur data suggest that DDR mutation as an indication of enhanced cancer immunity, and it may function as a biomarker for patients with CRCs receiving ICI treatment. The high incidence of DDR mutation in the Chinese CRC cohort emphasizes the future utility of panel-based DDR evaluation in guiding ICI treatment.

scholarly journals Pml nuclear body disruption cooperates in APL pathogenesis and impairs DNA damage repair pathways in mice

Blood ◽  
2018 ◽  
Vol 131 (6) ◽  
pp. 636-648 ◽  
Author(s):  
Edwige Voisset ◽  
Eva Moravcsik ◽  
Eva W. Stratford ◽  
Amie Jaye ◽  
Christopher J. Palgrave ◽  
...  
Keyword(s):  
Dna Damage ◽  
Targeted Therapy ◽  
Mouse Model ◽  
Mode Of Action ◽  
Dna Damage Repair ◽  
Nuclear Body ◽  
Damage Repair ◽  
Key Points ◽  
Repair Pathways ◽  
The Impact

Key Points A novel mouse model elucidates the impact of Pml NB disruption on APL pathogenesis and response to targeted therapy. The mode of action of this disruption appears to be via the perturbation of the NHEJ and HR pathways.

scholarly journals Germline predisposition to pediatric Ewing sarcoma is uniquely characterized by inherited pathogenic variants in DNA damage repair genes

2022 ◽  
Author(s):  
Riaz Gillani ◽  
Sabrina Y. Camp ◽  
Seunghun Han ◽  
Jill K. Jones ◽  
Schuyler O'Brien ◽  
...  
Keyword(s):  
Dna Damage ◽  
Ewing Sarcoma ◽  
Dna Damage Repair ◽  
Control Analysis ◽  
Biological Investigation ◽  
Germline Variants ◽  
Pathogenic Variants ◽  
Damage Repair ◽  
Pediatric Sarcoma ◽  
Repair Genes

More knowledge is needed around the role and importance of specific genes in germline predisposition to Ewing sarcoma to inform biological investigation and clinical practice. In this study, we evaluated the enrichment of pathogenic germline variants in Ewing sarcoma relative to other pediatric sarcoma subtypes, as well as patterns of inheritance of these variants. We carried out an ancestry-matched case-control analysis to screen for enrichment of pathogenic germline variants in 141 established cancer predisposition genes in 1138 individuals with pediatric sarcoma diagnoses (222 Ewing sarcoma cases) relative to identically processed cancer-free controls. Findings in Ewing sarcoma were validated with an additional cohort of 425 individuals, and 301 Ewing sarcoma parent-proband trios were analyzed for inheritance patterns of identified pathogenic variants. A distinct pattern of pathogenic germline variants was seen in Ewing sarcoma relative to other sarcoma subtypes. FANCC was the only gene with an enrichment signal for heterozygous pathogenic variants in the discovery Ewing sarcoma cohort (OR 14.4, 95% CI 3.5 - 51.2, p = 0.002, FDR = 0.28). This enrichment in FANCC heterozygous pathogenic variants was seen again in the Ewing sarcoma validation cohort (OR 5.1, 95% CI 1.2 - 18.5, p = 0.03, single hypothesis), representing a broader importance of genes involved in DNA damage repair, which were also nominally enriched in Ewing sarcoma cases. Pathogenic variants in DNA damage repair genes were acquired through autosomal inheritance. Our study provides new insight into germline risk factors contributing to Ewing sarcoma pathogenesis.

Functional analysis of patient-derived PALB2 missense variants of uncertain significance.

2020 ◽  
Vol 38 (15_suppl) ◽  
pp. 1531-1531
Author(s):  
Shijie Wu ◽  
Jiaojiao Zhou ◽  
Yiding Chen
Keyword(s):  
Breast Cancer ◽  
Functional Analysis ◽  
In Silico ◽  
Cancer Genetic Counseling ◽  
Wild Type ◽  
Variants Of Uncertain Significance ◽  
Missense Variants ◽  
Pathogenic Variants ◽  
Uncertain Significance ◽  
The Impact

1531 Background: Inherited PALB2 pathogenic variants are associated with an increased lifetime risk for breast cancer development. However, the interpretation of numerous PALB2 missense variants of uncertain significance (VUS) identified in germline genetic testing remains a challenge. Here, we assessed the impact of breast cancer patient-derived VUS on PALB2 function and identified pathogenic PALB2 missense variants that may increase cancer risk. Methods: A total of seven potentially pathogenic PALB2 VUS identified in 2,279 breast cancer patients were selected for functional analysis. All these selected VUS were assessed by SIFT, Align-GVGD, and PolyPhen2 in silico and were predicted to be deleterious by at least two in silico algorithms. The p.L35P [c.104T > C] variant was also included, for which pathogenicity has been recently confirmed. The effects of the VUS on the homologous recombination (HR) activity of PALB2 were tested by U2OS/DR-GFP reporting system. Functional characterization was further validated by protein co-immunoprecipitation and RAD51 recruitment assay. Results: PALB2 variants p.L24F [c.72G > C] and p.L35P [c.104T > C] showed the most significant disruption to the HR activity of PALB2 relative to the wild-type condition, retaining only 52.2% ( p = 0.0013) and 8.5% ( p < 0.0001) of HR activity respectively. Moderate but statistically significant HR deficiency was observed for four other variants (p.P405A [c.1213C > G], p.T1012I [c.3035C > T], p.E1018D [c.3054G > C], and p.T1099M [c.3296C > T]). We found no statistical differences for the p.K628N [c.1884G > T] and p.R663C [c.1987C > T] in the HR activity compared to wild-type PALB2. The p.L24F and p.L35P variants compromised the BRCA1-PALB2 interaction and reduced RAD51 foci formation in response to DNA damage. Conclusions: We have identified a novel patient-derived pathogenic PALB2 missense variant, p.L24F [c.72G > C], that compromises PALB2-mediated HR activity. We suggest the integration of the identified pathogenic variants into breast cancer genetic counseling and individualized treatment regimens for better clinical outcomes.

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