scholarly journals Genome Instability and Pressure on Non-Homologous end Joining drives Chemotherapy Resistance via a DNA Repair Crisis Switch in Triple Negative Breast Cancer.

2020 ◽  
Author(s):  
Adrian Wiegmans ◽  
Ambber Ward ◽  
Ekaterina Ivanova ◽  
Pascal H G Duijf ◽  
Romy VanOosterhout ◽  
...  
Keyword(s):  
Breast Cancer ◽  
Dna Repair ◽  
Homologous Recombination ◽  
Triple Negative Breast Cancer ◽  
Triple Negative ◽  
Genome Instability ◽  
Chemotherapy Resistance ◽  
End Joining ◽  
Repair Pathways ◽  
Non Homologous End Joining

Abstract Background: Chemotherapy intensifies pressure on the DNA repair pathways that can lead to deregulation. There is an urgent clinical need to be able to track the emergence of chemotherapy resistance and tailor patient staging appropriately. This is especially evident in the triple negative breast cancer (TNBC) subtype, of which standard of care is chemotherapy with tumours displaying high levels of inherent genome instability. TNBC has an overall poor prognosis for survival. There have been numerous studies into single agent chemoresistance but to date no study has elucidated in detail the roles of the key DNA repair components in resistance associated with the frontline clinical combination of anthracyclines and taxanes together. Methods: In this study, we hypothesized that the emergence of chemotherapy resistance is driven by changes in functional signaling in the DNA repair pathways. We identified the importance of the DNA repair pathways in chemoresistant clinical samples and characterized the emergence of chemoresistance in TNBC cell lines. We utilized classical DNA repair assays and specific targeting of key DNA repair proteins to elucidate a new mechanism for adaptation to the combination of doxorubicin and docetaxel. Results: We identified that consistent pressure on the non-homologous end joining pathway in the presence of genome instability causes failure of the key kinase DNA-PK, loss of p53 and compensation by p73. In-turn a switch to reliance on the homologous recombination pathway and RAD51 recombinase occurs to repair residual double strand DNA breaks. Conclusions: We demonstrate that RAD51 is an actionable target for resensitization to chemotherapy in resistant cells with a matched gene expression profile of resistance highlighted by homologous recombination.

scholarly journals Genome instability and pressure on non-homologous end joining drives chemotherapy resistance via a DNA repair crisis switch in triple negative breast cancer

NAR Cancer ◽  
2021 ◽  
Vol 3 (2) ◽  
Author(s):  
Adrian P Wiegmans ◽  
Ambber Ward ◽  
Ekaterina Ivanova ◽  
Pascal H G Duijf ◽  
Mark N Adams ◽  
...  
Keyword(s):  
Breast Cancer ◽  
Dna Repair ◽  
Homologous Recombination ◽  
Triple Negative Breast Cancer ◽  
Triple Negative ◽  
Genome Instability ◽  
Chemotherapy Resistance ◽  
End Joining ◽  
Repair Pathways ◽  
Non Homologous End Joining

Abstract Chemotherapy is used as a standard-of-care against cancers that display high levels of inherent genome instability. Chemotherapy induces DNA damage and intensifies pressure on the DNA repair pathways that can lead to deregulation. There is an urgent clinical need to be able to track the emergence of DNA repair driven chemotherapy resistance and tailor patient staging appropriately. There have been numerous studies into chemoresistance but to date no study has elucidated in detail the roles of the key DNA repair components in resistance associated with the frontline clinical combination of anthracyclines and taxanes together. In this study, we hypothesized that the emergence of chemotherapy resistance in triple negative breast cancer was driven by changes in functional signaling in the DNA repair pathways. We identified that consistent pressure on the non-homologous end joining pathway in the presence of genome instability causes failure of the key kinase DNA-PK, loss of p53 and compensation by p73. In-turn a switch to reliance on the homologous recombination pathway and RAD51 recombinase occurred to repair residual double strand DNA breaks. Further we demonstrate that RAD51 is an actionable target for resensitization to chemotherapy in resistant cells with a matched gene expression profile of resistance highlighted by homologous recombination in clinical samples.

scholarly journals Prevention of DNA Replication Stress by CHK1 Leads to Chemoresistance Despite a DNA Repair Defect in Homologous Recombination in Breast Cancer

Cells ◽  
2020 ◽  
Vol 9 (1) ◽  
pp. 238 ◽  
Author(s):  
Felix Meyer ◽  
Saskia Becker ◽  
Sandra Classen ◽  
Ann Christin Parplys ◽  
Wael Yassin Mansour ◽  
...  
Keyword(s):  
Breast Cancer ◽  
Dna Repair ◽  
Homologous Recombination ◽  
Triple Negative Breast Cancer ◽  
Chromosomal Instability ◽  
Triple Negative ◽  
Replication Stress ◽  
S Phase ◽  
Damage Response ◽  
Repair Defect

Chromosomal instability not only has a negative effect on survival in triple-negative breast cancer, but also on the well treatable subgroup of luminal A tumors. This suggests a general mechanism independent of subtypes. Increased chromosomal instability (CIN) in triple-negative breast cancer (TNBC) is attributed to a defect in the DNA repair pathway homologous recombination. Homologous recombination (HR) prevents genomic instability by repair and protection of replication. It is unclear whether genetic alterations actually lead to a repair defect or whether superior signaling pathways are of greater importance. Previous studies focused exclusively on the repair function of HR. Here, we show that the regulation of HR by the intra-S-phase damage response at the replication is of overriding importance. A damage response activated by Ataxia telangiectasia and Rad3 related-checkpoint kinase 1 (ATR-CHK1) can prevent replication stress and leads to resistance formation. CHK1 thus has a preferred role over HR in preventing replication stress in TNBC. The signaling cascade ATR-CHK1 can compensate for a double-strand break repair error and lead to resistance of HR-deficient tumors. Established methods for the identification of HR-deficient tumors for Poly(ADP-Ribose)-Polymerase 1 (PARP1) inhibitor therapies should be extended to include analysis of candidates for intra-S phase damage response.

scholarly journals Targeting mTOR and DNA repair pathways in residual triple negative breast cancer post neoadjuvant chemotherapy

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Kartik Anand ◽  
Tejal Patel ◽  
Polly Niravath ◽  
Angel Rodriguez ◽  
Jorge Darcourt ◽  
...  
Keyword(s):  
Breast Cancer ◽  
Dna Repair ◽  
Neoadjuvant Chemotherapy ◽  
Triple Negative Breast Cancer ◽  
Triple Negative ◽  
Small Sample ◽  
Pathologic Response ◽  
Residual Cancer ◽  
Repair Pathways ◽  
Definitive Surgery

AbstractTriple-negative breast cancer (TNBC) patients who do not achieve pathologic complete response post neoadjuvant chemotherapy have a poor prognosis. Alteration in PI3K/mTOR plus DNA repair pathways are some of the major mechanisms of chemotherapy resistance. We designed an open-label phase II clinical trial to evaluate if the combination of everolimus (mTOR inhibitor) plus cisplatin (interferes with DNA function) will improve the rate of pathologic response, as assessed by residual cancer burden (RCB). Twenty-four Stage II/III TNBC patients with residual cancer > 1 cm post neoadjuvant anthracycline and taxane-based chemotherapy were enrolled. Patients received everolimus daily orally at 10 mg for 12 weeks and cisplatin IV at 20 mg/m2 weekly for 4 cycles (21-day cycle), until definitive surgery. The primary endpoint was the rate of RCB-0-I at the surgery. The median age of the whole cohort was 50.1 years, with 66.7% non-Hispanic Caucasians. Of the 24 patients enrolled, 22 were included in the efficacy analysis. Twenty-one patients underwent definitive surgery while one patient developed distant metastasis. Five patients had RCB-I at surgery, a response rate of 23% (5/22). Patients with germline PALB2 mutation or somatic PI3KCA mutation had a pathologic response, achieving RCB-I at the surgery. Three patients had metaplastic histology achieving RCB-I at the surgery. Estimated OS at 1 year was 100% in the RCB-I group vs. 76.5% in others, which was not statistically significant due to the small sample size. Certain cohorts including PALB2 germline mutation carrier and somatic PI3KCA mutations warrant further investigation.Trial registration: Clinicaltrials.gov identifier: NCT01931163. https://clinicaltrials.gov/ct2/show/NCT01931163.

scholarly journals Determination of the DNA repair pathways utilised by acute lymphoblastic leukaemia cells following daunorubicin treatment

2019 ◽  
Vol 12 (1) ◽  
Author(s):  
Hussain Mubarak Al-Aamri ◽  
Helen R. Irving ◽  
Terri Meehan-Andrews ◽  
Christopher Bradley
Keyword(s):  
Dna Repair ◽  
Homologous Recombination ◽  
Cell Lines ◽  
Dna Lesions ◽  
Dna Double Strand Breaks ◽  
End Joining ◽  
Dsb Repair ◽  
Histone H2ax ◽  
Repair Pathways ◽  
Non Homologous End Joining

Abstract Objective DNA double strand breaks (DNA-DSBs) are among the most lethal DNA lesions leading to genomic instability and repaired by either homologous recombination (HR) or the non-homologous end joining (NHEJ) mechanisms. The purpose of this study was to assess the importance and the level of activation of non-homologous end joining (NHEJ) and homologous recombination (HR) DNA repair pathways in three cell lines, CCRF-CEM and MOLT-4 derived from T lymphocytes and SUP-B15 derived from B lymphocytes following treatment with chemotherapy agent daunorubicin. Results The Gamma histone H2AX (γH2AX) assay was used assess the effects of DNA-PK inhibitor NU7026 and RAD51 inhibitor RI-2 on repair of DNA-DSB following treatment with daunorubicin. In all cell lines, the NHEJ DNA repair pathway appeared more rapid and efficient. MOLT-4 and CCFR-CEM cells utilised both NHEJ and HR pathways for DNA-DSB repair. Whereas, SUP-B15 cells utilised only NHEJ for DSB repair, suggestive of a deficiency in HR repair pathways.

scholarly journals Integrin α6β4 signaling switches DNA repair from homologous recombination to non-homologous end-joining pathway to sensitize breast cancer cells to cisplatin

2019 ◽  
Author(s):  
Min Chen ◽  
Brock Marrs ◽  
Lei Qi ◽  
Teresa Knifley ◽  
Stuart G. Jarrett ◽  
...  
Keyword(s):  
Breast Cancer ◽  
Dna Repair ◽  
Homologous Recombination ◽  
Genetic Manipulation ◽  
Strand Break ◽  
End Joining ◽  
Apoptosis Resistance ◽  
Integrin Α6β4 ◽  
Cisplatin Sensitivity ◽  
Non Homologous End Joining

AbstractIntegrin α6β4 is highly expressed in triple negative breast cancer (TNBC) and drives aggressiveness by stimulating proliferation, angiogenesis, cell migration, invasion and metastasis. Signaling from this integrin stimulates DNA repair and apoptosis resistance, suggesting that it could contribute to therapeutic resistance. Upon testing this hypothesis, we found that integrin α6β4 signaling promoted a three-fold greater sensitivity to cisplatin but exhibited no difference in response to other chemotherapies tested. Mechanistic investigations revealed that integrin α6β4 stimulated quicker and higher amplitude of activation of ATM, Chk2, p53, and 53BP1, which required the integrin β4 signaling domain. Genetic manipulation of gene expression demonstrated that mutant p53 cooperated with integrin α6β4 for cisplatin sensitivity and was necessary for downstream phosphorylation of 53BP1 and enhanced ATM activation. Additionally, we discovered that integrin α6β4 preferentially activated DNA-PKc in response to cisplatin, which led to formation of DNA-PKc-p53 complexes and 53BP1 activation. As a result, integrin α6β4 shifted double strand break repair from homologous recombination (HR) to non-homologous end joining (NHEJ). In summary, we discovered a novel function of integrin α6β4 in switching DSB repair from HR to NHEJ that results in cisplatin sensitivity in TNBC.

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