scholarly journals Sirtuin inhibition is synthetic lethal with BRCA1 or BRCA2 deficiency

2021 ◽  
Vol 4 (1) ◽  
Author(s):  
Ilirjana Bajrami ◽  
Callum Walker ◽  
Dragomir B. Krastev ◽  
Daniel Weekes ◽  
Feifei Song ◽  
...  
Keyword(s):  
Synthetic Lethality ◽  
Parp Inhibitor ◽  
Lethal Effect ◽  
Synthetic Lethal ◽  
Genetic Ablation ◽  
Adp Ribosylation ◽  
Gene Mutant ◽  
Gene Defects ◽  
Mechanistic Basis ◽  
Mutant Cells

AbstractPARP enzymes utilise NAD+ as a co-substrate for their enzymatic activity. Inhibition of PARP1 is synthetic lethal with defects in either BRCA1 or BRCA2. In order to assess whether other genes implicated in NAD+ metabolism were synthetic lethal with BRCA1 or BRCA2 gene defects, we carried out a genetic screen, which identified a synthetic lethality between BRCA1 and genetic inhibition of either of two sirtuin (SIRT) enzymes, SIRT1 or SIRT6. This synthetic lethal interaction was replicated using small-molecule SIRT inhibitors and was associated with replication stress and increased cellular PARylation, in contrast to the decreased PARylation associated with BRCA-gene/PARP inhibitor synthetic lethality. SIRT/BRCA1 synthetic lethality was reversed by genetic ablation of either PARP1 or the histone PARylation factor-coding gene HPF1, implicating PARP1/HPF1-mediated serine ADP-ribosylation as part of the mechanistic basis of this synthetic lethal effect. These observations suggest that PARP1/HPF1-mediated serine ADP-ribosylation, when driven by SIRT inhibition, can inadvertently inhibit the growth of BRCA-gene mutant cells.

scholarly journals Cohesin mutations are synthetic lethal with stimulation of WNT signaling

eLife ◽  
2020 ◽  
Vol 9 ◽  
Author(s):  
Chue Vin Chin ◽  
Jisha Antony ◽  
Sarada Ketharnathan ◽  
Anastasia Labudina ◽  
Gregory Gimenez ◽  
...  
Keyword(s):  
Wnt Signaling ◽  
Therapeutic Strategy ◽  
Synthetic Lethality ◽  
Mcf10a Cell ◽  
Synthetic Lethal ◽  
Deletion Mutations ◽  
Damage Repair ◽  
Genes Encoding ◽  
Mutant Cells ◽  
Gsk3 Inhibitor

Mutations in genes encoding subunits of the cohesin complex are common in several cancers, but may also expose druggable vulnerabilities. We generated isogenic MCF10A cell lines with deletion mutations of genes encoding cohesin subunits SMC3, RAD21, and STAG2 and screened for synthetic lethality with 3009 FDA-approved compounds. The screen identified several compounds that interfere with transcription, DNA damage repair and the cell cycle. Unexpectedly, one of the top ‘hits’ was a GSK3 inhibitor, an agonist of Wnt signaling. We show that sensitivity to GSK3 inhibition is likely due to stabilization of β-catenin in cohesin-mutant cells, and that Wnt-responsive gene expression is highly sensitized in STAG2-mutant CMK leukemia cells. Moreover, Wnt activity is enhanced in zebrafish mutant for cohesin subunits stag2b and rad21. Our results suggest that cohesin mutations could progress oncogenesis by enhancing Wnt signaling, and that targeting the Wnt pathway may represent a novel therapeutic strategy for cohesin-mutant cancers.

scholarly journals Cohesin mutations are synthetic lethal with stimulation of WNT signaling

2020 ◽  
Author(s):  
Chue Vin Chin ◽  
Jisha Antony ◽  
Sarada Ketharnathan ◽  
Gregory Gimenez ◽  
Kate M. Parsons ◽  
...  
Keyword(s):  
Wnt Signaling ◽  
Synthetic Lethality ◽  
Mcf10a Cell ◽  
Synthetic Lethal ◽  
Deletion Mutations ◽  
Damage Repair ◽  
Genes Encoding ◽  
Cohesin Subunit ◽  
Mutant Cells ◽  
Gsk3 Inhibitor

AbstractMutations in genes encoding subunits of the cohesin complex are common in several cancers, but may also expose druggable vulnerabilities. We generated isogenic MCF10A cell lines with deletion mutations of genes encoding cohesin subunits SMC3, RAD21 and STAG2 and screened for synthetic lethality with 3,009 FDA-approved compounds. The screen identified several compounds that interfere with transcription, DNA damage repair and the cell cycle. Unexpectedly, one of the top ‘hits’ was a GSK3 inhibitor, an agonist of Wnt signaling. We show that sensitivity to GSK3 inhibition is likely due to stabilization of β-catenin in cohesin mutant cells, and that Wnt-responsive gene expression is highly sensitized in STAG2-mutant CMK leukemia cells. Moreover, Wnt activity is enhanced in zebrafish mutant for cohesin subunit rad21. Our results suggest that cohesin mutations could progress oncogenesis by enhancing Wnt signaling, and that targeting the Wnt pathway may represent a novel therapeutic strategy for cohesin mutant cancers.

scholarly journals Geldanamycin-Derived HSP90 Inhibitors Are Synthetic Lethal with NRF2

2020 ◽  
Vol 40 (22) ◽  
Author(s):  
Liam Baird ◽  
Takafumi Suzuki ◽  
Yushi Takahashi ◽  
Eiji Hishinuma ◽  
Daisuke Saigusa ◽  
...  
Keyword(s):  
Target Genes ◽  
Synthetic Lethality ◽  
Drug Repositioning ◽  
Lethal Effect ◽  
Cancer Therapies ◽  
Dependent Manner ◽  
Hsp90 Inhibitors ◽  
Synthetic Lethal ◽  
Activating Mutations ◽  
Approved Drugs

ABSTRACT Activating mutations in KEAP1-NRF2 are frequently found in tumors of the lung, esophagus, and liver, where they are associated with aggressive growth, resistance to cancer therapies, and low overall survival. Despite the fact that NRF2 is a validated driver of tumorigenesis and chemotherapeutic resistance, there are currently no approved drugs which can inhibit its activity. Therefore, there is an urgent clinical need to identify NRF2-selective cancer therapies. To this end, we developed a novel synthetic lethal assay, based on fluorescently labeled isogenic wild-type and Keap1 knockout cell lines, in order to screen for compounds which selectively kill cells in an NRF2-dependent manner. Through this approach, we identified three compounds based on the geldanamycin scaffold which display synthetic lethality with NRF2. Mechanistically, we show that products of NRF2 target genes metabolize the quinone-containing geldanamycin compounds into more potent HSP90 inhibitors, which enhances their cytotoxicity while simultaneously restricting the synthetic lethal effect to cells with aberrant NRF2 activity. As all three of the geldanamycin-derived compounds have been used in clinical trials, they represent ideal candidates for drug repositioning to target the currently untreatable NRF2 activity in cancer.

scholarly journals A preliminary study on the synthetic lethal effect of berberine and olaparib on pancreatic cancer cells and its mechanism

2021 ◽  
Vol 233 ◽  
pp. 02023
Author(s):  
Chengyong Zhang ◽  
Tingting Yang ◽  
Xiaoting Chen ◽  
Jiexuan Xu ◽  
Danlu Liang ◽  
...  
Keyword(s):  
Pancreatic Cancer ◽  
Dna Damage ◽  
Cancer Cells ◽  
Oxidative Dna Damage ◽  
Parp Inhibitor ◽  
Cell Activity ◽  
Lethal Effect ◽  
Synthetic Lethal ◽  
Pancreatic Cancer Cells ◽  
Apoptosis Inhibitor

Pancreatic cancer is a kind of malignant tumor with high mortality rate. Early operation and late chemoradiotherapy are the treatment criteria, but the prognosis is still poor. Berberine, an alkaloid compound present in many herbal plants, is capable of inducing oxidative DNA damage and downregulating homologous recombination repair (HRR) in cancer cells. Poly (ADP ribose) polymerase-1 (PARP-1) is a sensor of DNA damage with key roles in DNA repair. In this study, we demonstrated that berberine and PARP inhibitor olaparib have a synthetic lethal effect on pancreatic cancer cells. The expression level of RAD51 were reduced by berberine. Correspondingly, PARP became hyperactivated in response to berberine treatment. When berberine is combined with olaparib, the expression of Rad51 and Parp are inhibited. The combination of berberine and olaparib synergistically inhibit cell activity and induce cell apoptosis. In addition, the synergistic effect of berberine and olaparib can be reversed by apoptosis inhibitor and necrosis inhibitor. Together, the results indicate that berberine combined with olaparib have a synthetic lethal effect on pancreatic cancer cells.

scholarly journals New Synthetic Lethality Re-Sensitizing Platinum-Refractory Cancer Cells to Cisplatin In Vitro: The Rationale to Co-Use PARP and ATM Inhibitors

2021 ◽  
Vol 22 (24) ◽  
pp. 13324
Author(s):  
Watson P. Folk ◽  
Alpana Kumari ◽  
Tetsushi Iwasaki ◽  
Erica K. Cassimere ◽  
Slovénie Pyndiah ◽  
...  
Keyword(s):  
Tumor Suppressor ◽  
Cancer Cells ◽  
Cisplatin Resistance ◽  
Synthetic Lethality ◽  
Lethal Effect ◽  
Parp Inhibition ◽  
Synthetic Lethal ◽  
Cisplatin Sensitivity ◽  
Platinum Refractory

The pro-apoptotic tumor suppressor BIN1 inhibits the activities of the neoplastic transcription factor MYC, poly (ADP-ribose) polymerase-1 (PARP1), and ATM Ser/Thr kinase (ATM) by separate mechanisms. Although BIN1 deficits increase cancer-cell resistance to DNA-damaging chemotherapeutics, such as cisplatin, it is not fully understood when BIN1 deficiency occurs and how it provokes cisplatin resistance. Here, we report that the coordinated actions of MYC, PARP1, and ATM assist cancer cells in acquiring cisplatin resistance by BIN1 deficits. Forced BIN1 depletion compromised cisplatin sensitivity irrespective of Ser15-phosphorylated, pro-apoptotic TP53 tumor suppressor. The BIN1 deficit facilitated ATM to phosphorylate the DNA-damage-response (DDR) effectors, including MDC1. Consequently, another DDR protein, RNF8, bound to ATM-phosphorylated MDC1 and protected MDC1 from caspase-3-dependent proteolytic cleavage to hinder cisplatin sensitivity. Of note, long-term and repeated exposure to cisplatin naturally recapitulated the BIN1 loss and accompanying RNF8-dependent cisplatin resistance. Simultaneously, endogenous MYC was remarkably activated by PARP1, thereby repressing the BIN1 promoter, whereas PARP inhibition abolished the hyperactivated MYC-dependent BIN1 suppression and restored cisplatin sensitivity. Since the BIN1 gene rarely mutates in human cancers, our results suggest that simultaneous inhibition of PARP1 and ATM provokes a new BRCAness-independent synthetic lethal effect and ultimately re-establishes cisplatin sensitivity even in platinum-refractory cancer cells.

scholarly journals A high-content screen identifies the vulnerability of MYC-overexpressing cells to dimethylfasudil

2019 ◽  
Author(s):  
Jing Zhang ◽  
Shenqiu Zhang ◽  
Qiong Shi ◽  
Thaddeus D. Allen ◽  
Fengming You ◽  
...  
Keyword(s):  
Cell Lines ◽  
Synthetic Lethality ◽  
Human Cancer ◽  
Lethal Effect ◽  
Reversible Inhibitor ◽  
Synthetic Lethal Interaction ◽  
Synthetic Lethal ◽  
Human Cancer Cell Lines ◽  
Direct Targeting ◽  
Approved Drugs

AbstractA synthetic lethal effect arises when a cancer-associated change introduces a unique vulnerability to cancer cells that makes them unusually susceptible to a drug’s inhibitory activity. The synthetic lethal approach is attractive because it enables targeting of cancers harboring specific genomic alterations, the products of which may have proven refractory to direct targeting. An example is cancer driven by overexpression of MYC. Here, we conducted a high-content screen for compounds that are synthetic lethal to elevated MYC using a small-molecule library to identify compounds that are closely related to, or are themselves, regulatory-approved drugs. The screen identified dimethylfasudil, a potent and reversible inhibitor of Rho-associated kinases ROCK1 and ROCK2. Close analogs of dimethylfasudil are used clinically to treat neurologic and cardiovascular disorders. The synthetic lethal interaction was conserved in rodent and human cell lines and could be observed with activation of either MYC or its paralog MYCN. The synthetic lethality seems specific to MYC overexpressing cells as it could not be substituted by a variety of oncogenic manipulations and synthetic lethality was diminished by RNAi-mediated depletion of MYC in human cancer cell lines. Collectively, these data support investigation of the use of dimethylfasudil as a drug that is synthetic lethal for malignancies that specifically overexpress MYC.Significance StatementSynthetic lethal targeting of tumors overexpressing MYC holds promise for attacking aggressive malignancies. Here we describe a synthetic lethal interaction between dimethylfasudil and overexpression of MYC. Uniquely, this novel synthetic lethal interaction points toward an opportunity for synthetic lethality with a molecule likely to harbor favorable drug-like properties that enable systemic use.

scholarly journals Overview of Ferroptosis and Synthetic Lethality Strategies

2021 ◽  
Vol 22 (17) ◽  
pp. 9271
Author(s):  
Yuko Kinowaki ◽  
Towako Taguchi ◽  
Iichiroh Onishi ◽  
Susumu Kirimura ◽  
Masanobu Kitagawa ◽  
...  
Keyword(s):  
Epithelial Mesenchymal Transition ◽  
Synthetic Lethality ◽  
Therapeutic Strategies ◽  
Related Factors ◽  
Synthetic Lethal ◽  
Mesenchymal Transition ◽  
Genetic Abnormalities ◽  
Low Toxicity ◽  
New Research ◽  
Mutant Cells

Ferroptosis, a term first proposed in 2012, is iron-dependent, non-apoptotic regulatory cell death induced by erastin. Ferroptosis was originally discovered during synthetic lethal screening for drugs sensitive to RAS mutant cells, and is closely related to synthetic lethality. Ferroptosis sensitizes cancer stem cells and tumors that undergo epithelial−mesenchymal transition and are resistant to anticancer drugs or targeted therapy. Therefore, ferroptosis-inducing molecules are attractive new research targets. In contrast, synthetic lethal strategies approach mechanisms and genetic abnormalities that cannot be directly targeted by conventional therapeutic strategies, such as RAS mutations, hypoxia, and abnormalities in the metabolic environment. They also target the environment and conditions specific to malignant cells, have a low toxicity to normal cells, and can be used in combination with known drugs to produce new ones. However, the concept of synthetic lethality has not been widely adopted with ferroptosis. In this review, we surveyed the literature on ferroptosis-related factors and synthetic lethality to examine the potential therapeutic targets in ferroptosis-related molecules, focusing on factors related to synthetic lethality, discovery methods, clinical application stages, and issues in drug discovery.

scholarly journals Epigenetic based synthetic lethal strategies in human cancers

2020 ◽  
Vol 8 (1) ◽  
Author(s):  
Aiai Gao ◽  
Mingzhou Guo
Keyword(s):  
Synthetic Lethality ◽  
Parp Inhibitor ◽  
Parp Inhibitors ◽  
Epigenetic Changes ◽  
Loss Of Function ◽  
Synthetic Lethal ◽  
Human Cancers ◽  
Damage Repair ◽  
Frequent Event ◽  
Cancer Types

Abstract Over the past decades, it is recognized that loss of DNA damage repair (DDR) pathways is an early and frequent event in tumorigenesis, occurring in 40-50% of many cancer types. The basis of synthetic lethality in cancer therapy is DDR deficient cancers dependent on backup DNA repair pathways. In cancer, the concept of synthetic lethality has been extended to pairs of genes, in which inactivation of one by deletion or mutation and pharmacological inhibition of the other leads to death of cancer cells whereas normal cells are spared the effect of the drug. The paradigm study is to induce cell death by inhibiting PARP in BRCA1/2 defective cells. Since the successful application of PARP inhibitor, a growing number of developed DDR inhibitors are ongoing in preclinical and clinical testing, including ATM, ATR, CHK1/2 and WEE1 inhibitors. Combination of PARP inhibitors and other DDR inhibitors, or combination of multiple components of the same pathway may have great potential synthetic lethality efficiency. As epigenetics joins Knudson’s two hit theory, silencing of DDR genes by aberrant epigenetic changes provide new opportunities for synthetic lethal therapy in cancer. Understanding the causative epigenetic changes of loss-of-function has led to the development of novel therapeutic agents in cancer. DDR and related genes were found frequently methylated in human cancers, including BRCA1/2, MGMT, WRN, MLH1, CHFR, P16 and APC. Both genetic and epigenetic alterations may serve as synthetic lethal therapeutic markers.

scholarly journals Epigenetic synthetic lethality approaches in cancer therapy

2019 ◽  
Vol 11 (1) ◽  
Author(s):  
Haoshen Yang ◽  
Wei Cui ◽  
Lihui Wang
Keyword(s):  
Fusion Proteins ◽  
High Throughput Screening ◽  
Malignant Tumors ◽  
Synthetic Lethality ◽  
Parp Inhibitor ◽  
Synthetic Lethal ◽  
Epigenetic Regulators ◽  
Mutation Research ◽  
Synthetic Lethal Genes ◽  
Lethal Genes

Abstract The onset and development of malignant tumors are closely related to epigenetic modifications, and this has become a research hotspot. In recent years, a variety of epigenetic regulators have been discovered, and corresponding small molecule inhibitors have been developed, but their efficacy in solid tumors is generally poor. With the introduction of the first synthetic lethal drug (the PARP inhibitor olaparib in ovarian cancer with BRCA1 mutation), research into synthetic lethality has also become a hotspot. High-throughput screening with CRISPR-Cas9 and shRNA technology has revealed a large number of synthetic lethal pairs involving epigenetic-related synthetic lethal genes, such as those encoding SWI/SNF complex subunits, PRC2 complex subunits, SETD2, KMT2C, and MLL fusion proteins. In this review, we focus on epigenetic-related synthetic lethal mechanisms, including synthetic lethality between epigenetic mutations and epigenetic inhibitors, epigenetic mutations and non-epigenetic inhibitors, and oncogene mutations and epigenetic inhibitors.

scholarly journals Polθ inhibitors elicit BRCA-gene synthetic lethality and target PARP inhibitor resistance

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Diana Zatreanu ◽  
Helen M. R. Robinson ◽  
Omar Alkhatib ◽  
Marie Boursier ◽  
Harry Finch ◽  
...  
Keyword(s):  
Dna Repair ◽  
Synthetic Lethality ◽  
Parp Inhibitor ◽  
Repair Process ◽  
End Joining ◽  
Synthetic Lethal ◽  
Non Homologous End Joining ◽  
Inhibitor Resistance

AbstractTo identify approaches to target DNA repair vulnerabilities in cancer, we discovered nanomolar potent, selective, low molecular weight (MW), allosteric inhibitors of the polymerase function of DNA polymerase Polθ, including ART558. ART558 inhibits the major Polθ-mediated DNA repair process, Theta-Mediated End Joining, without targeting Non-Homologous End Joining. In addition, ART558 elicits DNA damage and synthetic lethality in BRCA1- or BRCA2-mutant tumour cells and enhances the effects of a PARP inhibitor. Genetic perturbation screening revealed that defects in the 53BP1/Shieldin complex, which cause PARP inhibitor resistance, result in in vitro and in vivo sensitivity to small molecule Polθ polymerase inhibitors. Mechanistically, ART558 increases biomarkers of single-stranded DNA and synthetic lethality in 53BP1-defective cells whilst the inhibition of DNA nucleases that promote end-resection reversed these effects, implicating these in the synthetic lethal mechanism-of-action. Taken together, these observations describe a drug class that elicits BRCA-gene synthetic lethality and PARP inhibitor synergy, as well as targeting a biomarker-defined mechanism of PARPi-resistance.

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