scholarly journals ATM deficiency promotes progression of CRPC by enhancing Warburg effect

2019 ◽  
Vol 26 (1) ◽  
pp. 59-71 ◽  
Author(s):  
Lingfan Xu ◽  
Enze Ma ◽  
Tao Zeng ◽  
Ruya Zhao ◽  
Yulei Tao ◽  
...  
Keyword(s):  
Dna Repair ◽  
Warburg Effect ◽  
Molecular Mechanisms ◽  
Synthetic Lethality ◽  
Aerobic Glycolysis ◽  
Parp Inhibitor ◽  
Strand Break ◽  
Parp Inhibitors ◽  
Castration Resistant Prostate Cancer ◽  
Glucose Flux

ATM is a well-known master regulator of double strand break (DSB) DNA repair and the defective DNA repair has been therapeutically exploited to develop PARP inhibitors based on the synthetic lethality strategy. ATM mutation is found with increased prevalence in advanced metastatic castration-resistant prostate cancer (mCRPC). However, the molecular mechanisms underlying ATM mutation-driving disease progression are still largely unknown. Here, we report that ATM mutation contributes to the CRPC progression through a metabolic rather than DNA repair mechanism. We showed that ATM deficiency generated by CRISPR/Cas9 editing promoted CRPC cell proliferation and xenograft tumor growth. ATM deficiency altered cellular metabolism and enhanced Warburg effect in CRPC cells. We demonstrated that ATM deficiency shunted the glucose flux to aerobic glycolysis by upregulating LDHA expression, which generated more lactate and produced less mitochondrial ROS to promote CRPC cell growth. Inhibition of LDHA by siRNA or inhibitor FX11 generated less lactate and accumulated more ROS in ATM-deficient CRPC cells and therefore potentiated the cell death of ATM-deficient CRPC cells. These findings suggest a new therapeutic strategy for ATM-mutant CRPC patients by targeting LDHA-mediated glycolysis metabolism, which might be effective for the PARP inhibitor resistant mCRPC tumors.

scholarly journals A synergistic interaction between HDAC- and PARP inhibitors in childhood tumors with chromothripsis

2021 ◽  
Author(s):  
Umar Khalid ◽  
Milena Simovic ◽  
Murat Iskar ◽  
John KL Wong ◽  
Rithu Kumar ◽  
...  
Keyword(s):  
Synthetic Lethality ◽  
Parp Inhibitor ◽  
Strand Break ◽  
Parp Inhibitors ◽  
Synergistic Interaction ◽  
Parp Inhibition ◽  
Dna Double Strand Breaks ◽  
Strand Breaks ◽  
Dna Double Strand Break

ABSTRACTChromothripsis is a form of genomic instability characterized by the occurrence of tens to hundreds of clustered DNA double-strand breaks in a one-off catastrophic event. Rearrangements associated with chromothripsis are detectable in numerous tumor entities and linked with poor prognosis in some of these, such as Sonic Hedgehog medulloblastoma, neuroblastoma and osteosarcoma. Hence, there is a need for therapeutic strategies eliminating tumor cells with chromothripsis. Defects in DNA double-strand break repair, and in particular homologous recombination repair, have been linked with chromothripsis. Targeting DNA repair deficiencies by synthetic lethality approaches, we performed a synergy screen using drug libraries (n = 375 compounds, 15 models) combined with either a PARP inhibitor or cisplatin. This revealed a synergistic interaction between the HDAC inhibitor romidepsin and PARP inhibition. Functional assays, transcriptome analyses, and in vivo validation in patient-derived xenograft mouse models confirmed the efficacy of the combinatorial treatment.

scholarly journals Combined Strategies with Poly (ADP-Ribose) Polymerase (PARP) Inhibitors for the Treatment of Ovarian Cancer: A Literature Review

Diagnostics ◽  
2019 ◽  
Vol 9 (3) ◽  
pp. 87 ◽  
Author(s):  
Stergios Boussios ◽  
Peeter Karihtala ◽  
Michele Moschetta ◽  
Afroditi Karathanasi ◽  
Agne Sadauskaite ◽  
...  
Keyword(s):  
Ovarian Cancer ◽  
Dna Repair ◽  
Synthetic Lethality ◽  
Excision Repair ◽  
Parp Inhibitor ◽  
Advanced Ovarian Cancer ◽  
Pegylated Liposomal Doxorubicin ◽  
Parp Inhibitors ◽  
Parp Inhibition ◽  
Biologic Agent

Poly (ADP-ribose) polymerase (PARP) inhibitors are the first clinically approved drugs designed to exploit synthetic lethality, and were first introduced as a cancer-targeting strategy in 2005. They have led to a major change in the treatment of advanced ovarian cancer, and altered the natural history of a disease with extreme genetic complexity and defective DNA repair via homologous recombination (HR) pathway. Furthermore, additional mechanisms apart from breast related cancer antigens 1 and 2 (BRCA1/2) mutations can also result in HR pathway alterations and consequently lead to a clinical benefit from PARP inhibitors. Novel combinations of PARP inhibitors with other anticancer therapies are challenging, and better understanding of PARP biology, DNA repair mechanisms, and PARP inhibitor mechanisms of action is crucial. It seems that PARP inhibitor and biologic agent combinations appear well tolerated and clinically effective in both BRCA-mutated and wild-type cancers. They target differing aberrant and exploitable pathways in ovarian cancer, and may induce greater DNA damage and HR deficiency. The input of immunotherapy in ovarian cancer is based on the observation that immunosuppressive microenvironments can affect tumour growth, metastasis, and even treatment resistance. Several biologic agents have been studied in combination with PARP inhibitors, including inhibitors of vascular endothelial growth factor (VEGF; bevacizumab, cediranib), and PD-1 or PD-L1 (durvalumab, pembrolizumab, nivolumab), anti-CTLA4 monoclonal antibodies (tremelimumab), mTOR-(vistusertib), AKT-(capivasertib), and PI3K inhibitors (buparlisib, alpelisib), as well as MEK 1/2, and WEE1 inhibitors (selumetinib and adavosertib, respectively). Olaparib and veliparib have also been combined with chemotherapy with the rationale of disrupting base excision repair via PARP inhibition. Olaparib has been investigated with carboplatin and paclitaxel, whereas veliparib has been tested additionally in combination with temozolomide vs. pegylated liposomal doxorubicin, as well as with oral cyclophosphamide, and topoisomerase inhibitors. However, overlapping myelosuppression observed with PARP inhibitor and chemotherapy combinations requires further investigation with dose escalation studies. In this review, we discuss multiple clinical trials that are underway examining the antitumor activity of such combination strategies.

scholarly journals Inhibition of poly(ADP-ribose) polymerase activity affects its subcellular localization and DNA strand break rejoining.

2009 ◽  
Vol 56 (2) ◽  
Author(s):  
Nadezhda I Ryabokon ◽  
Artur Cieślar-Pobuda ◽  
Joanna Rzeszowska-Wolny
Keyword(s):  
Dna Repair ◽  
Parp Inhibitor ◽  
Strand Break ◽  
Parp Inhibitors ◽  
Polymerase Activity ◽  
Dna Strand Breaks ◽  
Strand Breaks ◽  
Dna Strand Break ◽  
Parp Activity ◽  
Dna Strand

Poly(ADP-ribose) polymerase (PARP) plays a crucial role in DNA repair. Modulation of its activity by stimulation or inhibition is considered as a potentially important strategy in clinical practice, especially to sensitize tumor cells to chemo- and radiotherapy through inhibition of DNA repair. Here we studied the effect of the three PARP inhibitors, 5-iodo-6-amino-benzopyrone (INH(2)BP), 1,5-isoquinolinediol (1,5-dihydroxyisoquinolinediol (1,5-IQD) and 8-hydroxy-2-methylquinazolin-4-[3H]one (NU1025), and for two of them the efficiency in slowing the rejoining of DNA strand breaks induced by H(2)O(2) was compared. Inhibition of PARP changed its intranuclear localization markedly; cells exposed to the inhibitor NU1025 showed a significant tendency to accumulate PARP in large foci, whereas in untreated cells its distribution was more uniform. The speed and efficiency of rejoining of H(2)O(2)-induced DNA strand breaks were lower in cells incubated with a PARP inhibitor, and the kinetics of rejoining were modulated in a different manner by each inhibitor. At a concentration of 100 microM the efficiency of the inhibitors could be ranked in the order NU1025 > IQD > INH(2)BP. The two first compounds were able to decrease the overall PARP activity below the level detected in control cells, while INH(2)BP showed up to 40% PARP activity after exposure to H(2)O(2).

scholarly journals Biomarkers for Homologous Recombination Deficiency in Cancer

2021 ◽  
Vol 11 (7) ◽  
pp. 612
Author(s):  
Svenja Wagener-Ryczek ◽  
Sabine Merkelbach-Bruse ◽  
Janna Siemanowski
Keyword(s):  
Dna Repair ◽  
Homologous Recombination ◽  
Molecular Mechanisms ◽  
Brca Mutation ◽  
Parp Inhibitor ◽  
Parp Inhibitors ◽  
Clinical Diagnostics ◽  
Clinical Samples ◽  
Dna Double Strand Breaks ◽  
Homologous Recombination Deficiency

DNA double-strand breaks foster tumorigenesis and cell death. Two distinct mechanisms can be activated by the cell for DNA repair: the accurate mechanism of homologous recombination repair or the error-prone non-homologous end joining. Homologous Recombination Deficiency (HRD) is associated with sensitivity towards PARP inhibitors (PARPi) and its determination is used as a biomarker for therapy decision making. Nevertheless, the biology of HRD is rather complex and the application, as well as the benefit of the different HRD biomarker assays, is controversial. Acquiring knowledge of the underlying molecular mechanisms is the main prerequisite for integration of new biomarker tests. This study presents an overview of the major DNA repair mechanisms and defines the concepts of HRR, HRD and BRCAness. Moreover, currently available biomarker assays are described and discussed with respect to their application for routine clinical diagnostics. Since patient stratification for efficient PARP inhibitor therapy requires determination of the BRCA mutation status and genomic instability, both should be established comprehensively. For this purpose, a broad spectrum of distinct assays to determine such combined HRD scores is already available. Nevertheless, all tests require careful validation using clinical samples to meet the criteria for their establishment in clinical testing.

scholarly journals Loss of E2F7 confers resistance to poly-ADP-ribose polymerase (PARP) inhibitors in BRCA2-deficient cells

2018 ◽  
Author(s):  
Kristen E. Clements ◽  
Tanay Thakar ◽  
Claudia M. Nicolae ◽  
Xinwen Liang ◽  
Hong-Gang Wang ◽  
...  
Keyword(s):  
Dna Repair ◽  
Homologous Recombination ◽  
Transcriptional Repression ◽  
Molecular Mechanisms ◽  
Parp Inhibitor ◽  
Chemotherapy Resistance ◽  
Clinical Problem ◽  
Parp Inhibitors ◽  
Cancer Therapies ◽  
Response To Chemotherapy

ABSTRACTBRCA proteins are essential for Homologous Recombination DNA repair, and their germline or somatic inactivation is frequently observed in human tumors. Understanding the molecular mechanisms underlying the response to chemotherapy of BRCA-deficient tumors is paramount for developing improved personalized cancer therapies. While PARP inhibitors have been recently approved for treatment of BRCA-mutant breast and ovarian cancers, resistance to these novel drugs remains a major clinical problem. Several mechanisms of chemoresistance in BRCA2-deficient cells have been identified. Rather than restoring normal recombination, these mechanisms result in stabilization of stalled replication forks, which normally are subjected to degradation in BRCA2-mutated cells. Here, we show that the transcriptional repressor E2F7 controls chemoresistance in BRCA2-deficient cells. We found that E2F7 depletion restores PARP inhibitor and cisplatin resistance in BRCA2-depleted cells. Moreover, we show that the mechanism underlying this activity involves increased expression of RAD51, a target for E2F7-mediated transcriptional repression, which enhances both Homologous Recombination DNA repair, and replication fork stability in BRCA2-deficient cells. Our work describes a new mechanism of chemotherapy resistance in BRCA2-deficient cells, and identifies E2F7 as a novel biomarker for tumor response to PARP inhibitor therapy.

scholarly journals Breast Cancer Predisposition Genes and Synthetic Lethality

2021 ◽  
Vol 22 (11) ◽  
pp. 5614
Author(s):  
Hannah E. Neiger ◽  
Emily L. Siegler ◽  
Yihui Shi
Keyword(s):  
Dna Repair ◽  
Synthetic Lethality ◽  
Parp Inhibitor ◽  
Cancer Therapeutics ◽  
Strand Break ◽  
Cancer Predisposition ◽  
Repair System ◽  
Brca1 And Brca2 ◽  
Single Strand Break ◽  
Predisposition Genes

BRCA1 and BRCA2 are tumor suppressor genes with pivotal roles in the development of breast and ovarian cancers. These genes are essential for DNA double-strand break repair via homologous recombination (HR), which is a virtually error-free DNA repair mechanism. Following BRCA1 or BRCA2 mutations, HR is compromised, forcing cells to adopt alternative error-prone repair pathways that often result in tumorigenesis. Synthetic lethality refers to cell death caused by simultaneous perturbations of two genes while change of any one of them alone is nonlethal. Therefore, synthetic lethality can be instrumental in identifying new therapeutic targets for BRCA1/2 mutations. PARP is an established synthetic lethal partner of the BRCA genes. Its role is imperative in the single-strand break DNA repair system. Recently, Olaparib (a PARP inhibitor) was approved for treatment of BRCA1/2 breast and ovarian cancer as the first successful synthetic lethality-based therapy, showing considerable success in the development of effective targeted cancer therapeutics. Nevertheless, the possibility of drug resistance to targeted cancer therapy based on synthetic lethality necessitates the development of additional therapeutic options. This literature review addresses cancer predisposition genes, including BRCA1, BRCA2, and PALB2, synthetic lethality in the context of DNA repair machinery, as well as available treatment options.

scholarly journals XRCC1 deficient triple negative breast cancers are sensitive to ATR, ATM and Wee1 inhibitor either alone or in combination with olaparib

2020 ◽  
Vol 12 ◽  
pp. 175883592097420
Author(s):  
Reem Ali ◽  
Adel Alblihy ◽  
Michael S. Toss ◽  
Mashael Algethami ◽  
Rabab Al Sunni ◽  
...  
Keyword(s):  
Breast Cancer ◽  
Dna Repair ◽  
Triple Negative ◽  
Germ Line ◽  
Synthetic Lethality ◽  
Excision Repair ◽  
Parp Inhibitor ◽  
Strand Break ◽  
Breast Cancers ◽  
Single Strand Break

Background: PARP inhibitor (PARPi) monotherapy is a new strategy in BRCA germ-line deficient triple negative breast cancer (TNBC). However, not all patients respond, and the development of resistance limits the use of PARPi monotherapy. Therefore, the development of alternative synthetic lethality strategy, including in sporadic TNBC, is a priority. XRCC1, a key player in base excision repair, single strand break repair, nucleotide excision repair and alternative non-homologous end joining, interacts with PARP1 and coordinates DNA repair. ATR, ATM and Wee1 have essential roles in DNA repair and cell cycle regulation. Methods: Highly selective inhibitors of ATR (AZD6738), ATM (AZ31) and Wee1 (AZD1775) either alone or in combination with olaparib were tested for synthetic lethality in XRCC1 deficient TNBC or HeLa cells. Clinicopathological significance of ATR, ATM or Wee1 co-expression in XRCC1 proficient or deficient tumours was evaluated in a large cohort of 1650 human breast cancers. Results: ATR (AZD6738), ATM (AZ31) or Wee1 (AZD1775) monotherapy was selectively toxic in XRCC1 deficient cells. Selective synergistic toxicity was evident when olaparib was combined with AZD6738, AZ31 or AZD1775. The most potent synergistic interaction was evident with the AZD6738 and olaparib combination therapy. In clinical cohorts, ATR, ATM or Wee1 overexpression in XRCC1 deficient breast cancer was associated with poor outcomes. Conclusion: XRCC1 stratified DNA repair targeted combinatorial approach is feasible and warrants further clinical evaluation in breast cancer.

In silico discovery of novel flavonoids as poly ADP ribose polymerase (PARP) inhibitors

2020 ◽  
Vol 16 ◽  
Author(s):  
Ashish Shah ◽  
Ghanshyam Parmar ◽  
Avinash Kumar Seth
Keyword(s):  
Virtual Screening ◽  
In Silico ◽  
Synthetic Lethality ◽  
Parp Inhibitor ◽  
Parp Inhibitors ◽  
Docking Studies ◽  
Docking Score ◽  
Docking Method ◽  
Anti Cancer ◽  
In Silico Toxicity

Background: The concept of synthetic lethality is emerging field in the treatment of cancer and can be applied for new drug development of cancer as it has been already represented by Poly (ADP-ribose) polymerase (PARPs) inhibitors. Objectives: In this study we performed virtual screening of 329 flavonoids obtained from Naturally Occurring Plant-based Anti-cancer Compound-Activity-Target (NPACT) database to identify novel PARP inhibitors. Materials and methods: Virtual screening carried out using different In Silico methods which includes molecular docking studies, prediction of druglikeness and In Silico toxicity studies. Results: Fifteen out of 329 flavonoids achieved better docking score as compared to rucaparib which is an FDA approved PARP inhibitor. These 15 hits were again rescored using accurate docking mode and drug-likeliness properties were evaluated. Accuracy of docking method was checked using re-docking. Finally NPACT00183 and NPACT00280 were identified as potential PARP inhibitors with docking score of -139.237 and -129.36 respectively. These two flavonoids were also showed no AMES toxicity and no carcinogenicity which was predicted using admetSAR. Conclusion: Our finding suggests that NPACT00183 and NPACT00280 have promising potential to be further explored as PARP inhibitors.

scholarly journals Predictors and Modulators of Synthetic Lethality: An Update on PARP Inhibitors and Personalized Medicine

2016 ◽  
Vol 2016 ◽  
pp. 1-12 ◽  
Author(s):  
Stephen Murata ◽  
Catherine Zhang ◽  
Nathan Finch ◽  
Kevin Zhang ◽  
Loredana Campo ◽  
...  
Keyword(s):  
Synthetic Lethality ◽  
Parp Inhibitor ◽  
Advanced Ovarian Cancer ◽  
Parp Inhibitors ◽  
Damage Repair ◽  
Trial Testing ◽  
United States Food ◽  
States Food ◽  
And Personalized Medicine ◽  
Inhibitor Treatment

Poly(ADP-ribose) polymerase (PARP) inhibitors have proven to be successful agents in inducing synthetic lethality in several malignancies. Several PARP inhibitors have reached clinical trial testing for treatment in different cancers, and, recently, Olaparib (AZD2281) has gained both United States Food and Drug Administration (USFDA) and the European Commission (EC) approval for use inBRCA-mutated advanced ovarian cancer treatment. The need to identify biomarkers, their interactions in DNA damage repair pathways, and their potential utility in identifying patients who are candidates for PARP inhibitor treatment is well recognized. In this review, we detail many of the biomarkers that have been investigated for their ability to predict both PARP inhibitor sensitivity and resistance in preclinical studies as well as the results of several clinical trials that have tested the safety and efficacy of different PARP inhibitor agents inBRCAand non-BRCA-mutated cancers.

scholarly journals Genome-wide and high-density CRISPR-Cas9 screens identify point mutations in PARP1 causing PARP inhibitor resistance

2017 ◽  
Author(s):  
Stephen J. Pettitt ◽  
Dragomir B. Krastev ◽  
Inger Brandsma ◽  
Amy Drean ◽  
Feifei Song ◽  
...  
Keyword(s):  
Catalytic Domain ◽  
Synthetic Lethality ◽  
Parp Inhibitor ◽  
Point Mutations ◽  
Underlying Mechanism ◽  
Parp Inhibitors ◽  
High Density ◽  
Single Amino Acid ◽  
Genome Wide ◽  
Amino Acid Mutations

AbstractPARP inhibitors (PARPi) target homologous recombination defective tumour cells via synthetic lethality. Genome-wide and high-density CRISPR-Cas9 “tag, mutate and enrich” mutagenesis screens identified single amino acid mutations in PARP1 that cause profound PARPi-resistance. These included PARP1 mutations outside of the DNA interacting regions of the protein, such as mutations in solvent exposed regions of the catalytic domain and clusters of mutations around points of contact between ZnF, WGR and HD domains. These mutations altered PARP1 trapping, as did a mutation found in a clinical case of PARPi resistance. These genetic studies reinforce the importance of trapped PARP1 as a key cytotoxic DNA lesion and suggest that interactions between non-DNA binding domains of PARP1 influence cytotoxicity. Finally, different mechanisms of PARPi resistance (BRCA1 reversion, PARP1, 53BP1, REV7 mutation) had differing effects on chemotherapy sensitivity, suggesting that the underlying mechanism of PARPi resistance likely influences the success of subsequent therapies.

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