scholarly journals IDH1-R132H acts as a tumor suppressor in glioma via epigenetic up-regulation of the DNA damage response

2019 ◽  
Vol 11 (479) ◽  
pp. eaaq1427 ◽  
Author(s):  
Felipe J. Núñez ◽  
Flor M. Mendez ◽  
Padma Kadiyala ◽  
Mahmoud S. Alghamri ◽  
Masha G. Savelieff ◽  
...  
Keyword(s):  
Dna Damage ◽  
Tumor Suppressor ◽  
Mouse Model ◽  
Dna Damage Response ◽  
Genetically Engineered ◽  
Low Grade ◽  
Loss Of Function ◽  
Genetically Engineered Mouse Model ◽  
Damage Response ◽  
Inactivating Mutations

Patients with glioma whose tumors carry a mutation in isocitrate dehydrogenase 1 (IDH1R132H) are younger at diagnosis and live longer. IDH1 mutations co-occur with other molecular lesions, such as 1p/19q codeletion, inactivating mutations in the tumor suppressor protein 53 (TP53) gene, and loss-of-function mutations in alpha thalassemia/mental retardation syndrome X-linked gene (ATRX). All adult low-grade gliomas (LGGs) harboring ATRX loss also express the IDH1R132H mutation. The current molecular classification of LGGs is based, partly, on the distribution of these mutations. We developed a genetically engineered mouse model harboring IDH1R132H, TP53 and ATRX inactivating mutations, and activated NRAS G12V. Previously, we established that ATRX deficiency, in the context of wild-type IDH1, induces genomic instability, impairs nonhomologous end-joining DNA repair, and increases sensitivity to DNA-damaging therapies. In this study, using our mouse model and primary patient-derived glioma cultures with IDH1 mutations, we investigated the function of IDH1R132H in the context of TP53 and ATRX loss. We discovered that IDH1R132H expression in the genetic context of ATRX and TP53 gene inactivation (i) increases median survival in the absence of treatment, (ii) enhances DNA damage response (DDR) via epigenetic up-regulation of the ataxia-telangiectasia–mutated (ATM) signaling pathway, and (iii) elicits tumor radioresistance. Accordingly, pharmacological inhibition of ATM or checkpoint kinases 1 and 2, essential kinases in the DDR, restored the tumors’ radiosensitivity. Translation of these findings to patients with IDH1132H glioma harboring TP53 and ATRX loss could improve the therapeutic efficacy of radiotherapy and, consequently, patient survival.

scholarly journals DIPG-68. ALPHA-THALASSEMIA X-LINKED MENTAL RETARDATION PROTEIN (ATRX) LOSS-OF-FUNCTION IN A MOUSE MODEL OF DIFFUSE INTRINSIC PONTINE GLIOMA

2020 ◽  
Vol 22 (Supplement_3) ◽  
pp. iii300-iii300
Author(s):  
Chen Shen ◽  
David Picketts ◽  
Oren Becher
Keyword(s):  
Mouse Model ◽  
Pediatric Brain Tumor ◽  
High Grade Glioma ◽  
Genetic Alterations ◽  
Genetically Engineered ◽  
Tumor Incidence ◽  
Loss Of Function ◽  
Nestin Expression ◽  
Genetically Engineered Mouse Model ◽  
Clinical Cases

Abstract Diffuse Intrinsic Potine Glioma (DIPG) is a rare pediatric brain tumor for which no cure or efficacious therapies exist. Previous discoveries have revealed that, DIPG harbors distinct genetic alterations, when compared with adult high-grade glioma (HGG) or even with non-DIPG pediatric HGGs. ATRX alteration is found in 9% of clinical cases of DIPG, and significantly overlaps with H3.3K27M mutation and p53 loss, the two most common genetic changes in DIPG, found in 80% and 77% clinical cases, respectively. Here we developed genetically engineered mouse model of brainstem glioma using the RCAS-Tv-a system by targeting PDGF-B overexpression, p53 loss, H3.3K27M mutation and ATRX loss-of function to Nestin-expression brainstem progenitor cells of the neonatal mouse. Specifically, we used Nestin-Tv-a; p53 floxed; ATRX heterozygous female and Nestin-Tv-a; p53 floxed; ATRX floxed male breeders, generated offsprings with ATRX loss of function (n=18), ATRX heterozygous females (n=6), and ATRX WT (n=10). Median survial of the three groups are 65 days, 88 days and 51 days, respectively. Also, ATRX null mice is lower in tumor incidence (44.4%), compared with ATRX WT (80%). We evaluated the pathological features of DIPG with or without ATRX alteration, RNA-seq is performed to identify differentially expressed genes between ATRX WT and loss-of-function. In conclution, this study generated the first genetically modified mouse model studying ATRX loss-of-function in DIPG, and suggested that ATRX loss-of-function in DIPG may slow down tumorigenesis and decrease tumor incidence.

scholarly journals Profilin-1; a novel regulator of DNA damage response and repair machinery in keratinocytes

2021 ◽  
Author(s):  
Chang-Jin Lee ◽  
Min-Ji Yoon ◽  
Dong Hyun Kim ◽  
Tae Uk Kim ◽  
Youn-Jung Kang
Keyword(s):  
Dna Damage ◽  
Dna Repair ◽  
Dna Damage Response ◽  
Recovery Time ◽  
Actin Polymerization ◽  
Loss Of Function ◽  
Dna Double Strand Breaks ◽  
Pten Loss ◽  
Damage Response ◽  
Specific Regulation

AbstractProfilin-1 (PFN1) regulates actin polymerization and cytoskeletal growth. Despite the essential roles of PFN1 in cell integration, its subcellular function in keratinocyte has not been elucidated yet. Here we characterize the specific regulation of PFN1 in DNA damage response and repair machinery. PFN1 depletion accelerated DNA damage-mediated apoptosis exhibiting PTEN loss of function instigated by increased phosphorylated inactivation followed by high levels of AKT activation. PFN1 changed its predominant cytoplasmic localization to the nucleus upon DNA damage and subsequently restored the cytoplasmic compartment during the recovery time. Even though γH2AX was recruited at the sites of DNA double strand breaks in response to DNA damage, PFN1-deficient cells failed to recruit DNA repair factors, whereas control cells exhibited significant increases of these genes. Additionally, PFN1 depletion resulted in disruption of PTEN-AKT cascade upon DNA damage and CHK1-mediated cell cycle arrest was not recovered even after the recovery time exhibiting γH2AX accumulation. This might suggest PFN1 roles in regulating DNA damage response and repair machinery to protect cells from DNA damage. Future studies addressing the crosstalk and regulation of PTEN-related DNA damage sensing and repair pathway choice by PFN1 may further aid to identify new mechanistic insights for various DNA repair disorders.

scholarly journals Early Detection in a Mouse Model of Pancreatic Cancer by Imaging DNA Damage Response Signaling

2019 ◽  
Vol 61 (7) ◽  
pp. 1006-1013
Author(s):  
James C. Knight ◽  
Julia Baguña Torres ◽  
Robert Goldin ◽  
Michael Mosley ◽  
Gemma M. Dias ◽  
...  
Keyword(s):  
Pancreatic Cancer ◽  
Dna Damage ◽  
Early Detection ◽  
Mouse Model ◽  
Dna Damage Response ◽  
Damage Response

scholarly journals DNA Damage Response is Prominent in Ovarian High-Grade Serous Carcinomas, Especially Those with Rsf-1 (HBXAP) Overexpression

2012 ◽  
Vol 2012 ◽  
pp. 1-7 ◽  
Author(s):  
Malti Kshirsagar ◽  
Wei Jiang ◽  
Ie-Ming Shih
Keyword(s):  
Dna Damage ◽  
Chromatin Remodeling ◽  
Dna Damage Response ◽  
Surrogate Marker ◽  
Serous Carcinoma ◽  
Low Grade ◽  
High Grade ◽  
Significant Difference ◽  
Damage Response ◽  
Microenvironmental Stress

DNA damage commonly occurs in cancer cells as a result of endogenous and tumor microenvironmental stress. In this study, we applied immunohistochemistry to study the expression of phosphorylated Chk2 (pChk2), a surrogate marker of the DNA damage response, in high grade and low grade of ovarian serous carcinoma. A phospho-specific antibody specific for threonine 68 of Chk2 was used for immunohistochemistry on a total of 292 ovarian carcinoma tissues including 250 high-grade and 42 low-grade serous carcinomas. Immunostaining intensity was correlated with clinicopathological features. We found that there was a significant correlation between pChk2 immunostaining intensity and percentage of pChk2 positive cells in tumors and demonstrated that high-grade serous carcinomas expressed an elevated level of pChk2 as compared to low-grade serous carcinomas. Normal ovarian, fallopian tube, ovarian cyst, and serous borderline tumors did not show detectable pChk2 immunoreactivity. There was no significant difference in pChk2 immunoreactivity between primary and recurrent high-grade serous carcinomas. In high-grade serous carcinomas, a significant correlation (P<0.0001) in expression level (both in intensity and percentage) was found between pChk2 and Rsf-1 (HBXAP), a gene involved in chromatin remodeling that is amplified in high-grade serous carcinoma. Our results suggest that the DNA damage response is common in high-grade ovarian serous carcinomas, especially those with Rsf-1 overexpression, suggesting that Rsf-1 may be associated with DNA damage response in high-grade serous carcinomas.

scholarly journals Normal ABL1 Is a Tumor Suppressor and Therapeutic Target In BCR-ABL1–positive Leukemias

Blood ◽  
2013 ◽  
Vol 122 (21) ◽  
pp. 1466-1466
Author(s):  
Yashodhara Dasgupta ◽  
Mateusz Koptyra ◽  
Margaret Nieborowska-Skorska ◽  
Elisabeth Bolton Gillespie ◽  
Tomasz Stoklosa ◽  
...  
Keyword(s):  
Stem Cells ◽  
Dna Damage ◽  
Tumor Suppressor ◽  
Dna Damage Response ◽  
Chromosome 9 ◽  
Myeloid Differentiation ◽  
Damage Response ◽  
Kinase Expression ◽  
Stimulation Of

Abstract BCR-ABL1 results from t(9;22)(q34;q11) reciprocal translocation resulting in BCR-ABL1 kinase expression, initiating chronic myeloid leukemia in chronic phase (CML-CP). At the initial stages of CML-CP both oncogenic BCR-ABL1 kinase and normal ABL1 kinase are expressed, however, loss of ABL1 kinase expression in CML-CP can result from an interstitial deletion in the normal chromosome 9 [del(9q34)] which may be combined with the transcriptional silencing of the alternative ABL1 promoter within the translocation eventually leading to disease progression and drug resistance. We found that BCR-ABL1 Abl1-/- cells generated a CML-blast phase (BP)-like disease phenotype in SCID mice compared to CML-CP-like disease from BCR-ABL1 Abl1+/+ cells. To determine the mechanisms responsible for blastic transformation of BCR-ABL1 Abl1-/- cells, we examined the role of ABL1 in proliferation, differentiation, apoptosis, genomic instability, and stemness. The presence of ABL1 inhibited proliferation in BCR-ABL1 cells as BCR-ABL1 Abl1-/- cells had higher clonogenic activity and proliferative rate compared to their wild-type counterparts. ABL1 is essential for myeloid differentiation since BCR-ABL1 Abl1-/- cells showed an immature blast phenotype when stained with Wright-Giemsa and myeloid differentiation markers Gr-1 and CD11b. ABL1 promoted apoptosis in response to genotoxic stress as revealed by reduced clonogenicity and elevated expression of p53, phosphoserine-15 p53 and activated caspase 3 in BCR-ABL1 Abl1 +/+ compared to knock-out cells. Although the absence of ABL1 did not enhance ROS and oxidative DNA damage, it appears that an impaired DNA damage response may be responsible for higher chromosome numbers and an accumulation of high numbers of chromosomal aberrations in BCR-ABL1 Abl1-/- cells. We detected an expansion of Lin-c-Kit+Sca-1+ leukemia stem cells (LSCs) in BCR-ABL1 Abl1-/- cells compared to BCR-ABL1 Abl1+/+ or non-transformed counterparts; among the LSCs, there was a higher percentage of CD34-Flt3- long-term and CD34+Flt3-short-term stem cells. These results showed that ABL1 is involved in regulating the LSC compartment in BCR-ABL1 cells. DNA microarray analysis revealed changes in mRNA levels of several genes involved in proliferation, myeloid differentiation, apoptosis, DNA damage response and stemness in BCR-ABL1 Abl1-/- cells in comparison to BCR-ABL1 Abl1+/+ cells. Together, these results demonstrated a critical role of ABL1 in BCR-ABL1-induced leukemia, prolonging survival in mice by suppressing proliferation and expansion of LSC, inducing myeloid differentiation, apoptosis and DNA damage response in BCR-ABL1 cells. Thus, it appears that ABL1 acts as a tumor suppressor in BCR-ABL1 –positive CML cells. Moreover, we hypothesized that the enhancement of the tumor suppressor function of ABL1 may have a significant impact on CML treatment. A small molecule activator of ABL1 kinase, 5-(1,3-diaryl-1H-pyrazol-4-yl)hydantoin (DPH), had been reported to interact with the myristoyl-binding site of ABL1 and destabilize the bent conformation of the α-1 helix, thereby preventing the auto-inhibitory conformation. DPH partially restored ABL1 activity in imatinib-treated cells. DPH-mediated stimulation of ABL1 tumor suppressor activity enhanced the effect of imatinib and ponatinib against CML CD34+ cells, Philadelphia chromosome-positive B-ALL (Ph+B-ALL) cells and relapsed Ph+B-ALL cells harboring T315I mutation without affecting normal counterparts. In summary, ABL1 is a potential tumor suppressor in BCR-ABL1-induced leukemia and stimulation of its function may play a significant role in the development of novel therapeutic strategies for CML and Ph+ALL. Disclosures: No relevant conflicts of interest to declare.

Exploring impact of mutations in non-BRCA DNA damage response (DDR) and non-DDR genes on efficacy in phase III EMBRACA study of talazoparib (TALA) in patients (pts) with germline BRCA1/2 mutated (gBRCAm) HER2-negative (HER2-) advanced breast cancer (ABC).

2020 ◽  
Vol 38 (15_suppl) ◽  
pp. 1018-1018
Author(s):  
Jennifer Keating Litton ◽  
Douglas Laird ◽  
Hope S. Rugo ◽  
Johannes Ettl ◽  
Sara A. Hurvitz ◽  
...  
Keyword(s):  
Dna Damage ◽  
Dna Damage Response ◽  
Tumor Response ◽  
Brca Mutation ◽  
Phase Iii ◽  
Loss Of Function ◽  
Single Nucleotide Variants ◽  
Tp53 Mutations ◽  
Mutational Status ◽  
Damage Response

1018 Background: Loss-of-function mutations in genes encoding components of the homologous recombination DNA damage response (DDR) machinery, notably BRCA1/2, are associated with tumor sensitivity to poly(ADP-ribose) polymerase inhibitors (PARPi). In EMBRACA, the PARPi TALA showed an improvement in progression-free survival (PFS) (HR [95% CI] 0.54 [0.41-0.71], P < 0.001) vs physician's choice of chemotherapy (PCT) in g BRCAm HER2− ABC. Methods: Baseline tumor tissue from 308 pts (71%; intent-to-treat) was sequenced using the FoundationOne CDx panel. Mutations summarized below were known/likely pathogenic single-nucleotide variants, insertions, deletions, or rearrangements. Best tumor response (BOR) was using RECIST 1.1 by Investigator (confirmation of CR or PR not required). Results: 296/308 (96%) of evaluable pts exhibited ≥1 tumor BRCA mutation, with 7 of the remaining 12 exhibiting BRCA copy number alterations deemed pathogenic. Mutations in other genes implicated in DDR and/or potential sensitization to PARPi were rare, with mutations detected in BARD1, CDK12, FANCG, STAG2 (each 0.3%), ATR, BRD4, FANCC, PALB2, RAD51B (0.6%), ATM, BRIP1 (1.0%), NBN (1.3%), CHEK2, FANCA (1.6%), and ARID1A (2.3%). No association was observed between total number of DDR mutations, including BRCA1/2, and best tumor response (BOR) [odds ratio of 1 vs ≥2 DDR mutations (95% CI): TALA, 0.76 (0.31-1.87), P = 0.55; PCT, 0.98 (0.27-3.51), P = 0.97]. TP53 and PIK3CA were the most commonly mutated non- BRCA genes in BRCAm tumors (52.0 and 10.8%, respectively). TP53 mutations were more prevalent in BRCA1m vs BRCA2m tumors (85.2 vs 24.8%). PIK3CA mutations were more prevalent in BRCA2m vs BRCA1m tumors (15.9 vs 5.2%). With TALA, PFS was significantly shorter in pts with TP53 mutations than without [HR (95% CI) 1.693 (1.186-2.418), P = 0.0033]. A similar, non-significant, trend was evident with PCT [HR (95% CI) 1.439 (0.859-2.411), P = 0.1614]. PIK3CA mutational status had no impact on PFS in either arm. Conclusions: Selection based on g BRCA mutational status is appropriate to identify HER2─ ABC pts with potential for clinical benefit from TALA, with the total number of tumor mutations in BRCA1/2 and other DDR genes not impacting response (within the g BRCAm subset). TP53 mutations were associated with shorter PFS, likely reflecting the worse outcomes observed in g BRCA1m patients. Additional correlative analyses are ongoing. Clinical trial information: NCT01945775 .

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