The Experts below are selected from a list of 1668 Experts worldwide ranked by ideXlab platform
Dominic I James - One of the best experts on this subject based on the ideXlab platform.
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abstract 1943 PARG inhibitors exhibit synthetic lethality with xrcc1 deficiency and a cellular mechanism of action that is distinct from parp inhibition
Cancer Research, 2018Co-Authors: Leenus Martin, Dominic I James, Allan M Jordan, Ian D Waddell, Tzuling Cheng, Habiba Begum, Kate M Smith, Kedar S Vaidya, Marcus Fischer, Bing YaoAbstract:Poly(ADP-ribose) glycohydrolase (PARG) hydrolyzes poly(ADP-ribose) (PAR) chains that are polymerized by PARP enzymes, completing the PAR cycle. Small molecule inhibitors of PARG result in a dose dependent increase in cellular PAR after DNA damage. Here we demonstrate that depletion of XRCC1, a scaffolding protein with an essential role in base-excision repair (BER), sensitizes cancer cells to PARG inhibition. XRCC1 deficient cells exhibit increased nuclear PAR foci in response to PARG inhibition even in the absence of DNA damaging agents. Inhibition of PARP1 with RNAi or small molecule inhibitors rescues cell growth inhibition and reduces the amount of cellular PAR accumulation in PARG inhibitor treated cells. This indicates that the cellular growth inhibition is dependent upon cellular PAR levels, demonstrating selectivity of the small molecule inhibitors for PARG. We hypothesized that inhibition of PAR hydrolysis could result in depletion of cellular NAD as this could prevent recycling of PAR to NAD. Consistent with this hypothesis, PARG inhibition enhanced NAD depletion after treatment of cells with the DNA damaging agent methyl methanesulfonate (MMS). Live cell imaging of XRCC1 depleted cells treated with a PARG inhibitor revealed that cells have large membrane protrusions, similar to the morphology of cells that have been treated with a NAMPT inhibitor, which results in depletion of cellular NAD. Furthermore, addition of the NAD precursor, nicotinamide mononucleotide (NMN) rescued proliferation of PARG inhibited cells. Taken together, these data support a hypothesis in which PARG inhibitors are cytotoxic to sensitive cancer cells via depletion of NAD, ultimately starving the cell of ATP. Thus, PARG inhibition is a novel strategy for exploiting synthetic lethality in cancer cells. The defects that sensitize cancer cells to PARG inhibition are distinct from those that sensitize to PARP inhibitors, namely defects in homology directed repair. Approximately 15% of breast cancer samples exhibit low or no XRCC1 by IHC. A subset (approximately 35%) of the XRCC1 low patient samples also have defects in BRCA1, suggesting that the majority of XRCC1 low tumors may not be responsive to PARP inhibitors. Small molecule PARG inhibitors are currently being evaluated for efficacy in XRCC1 low xenograft models. Citation Format: Leenus Martin, Tzuling Cheng, Dominic I. James, Habiba Begum, Kate M. Smith, Allan Jordan, Ian Waddell, Kedar Vaidya, Marcus Fischer, Bing Yao, Jason Drummond, Leah Cleary, Ruben Martinez, James Sutton, Nandini Ravindran, James Joseph, Eleni Venetsanakos, Michael Dillon, Jeffrey H. Hager, Lisa D. Belmont. PARG inhibitors exhibit synthetic lethality with XRCC1 deficiency and a cellular mechanism of action that is distinct from PARP inhibition [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2018; 2018 Apr 14-18; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2018;78(13 Suppl):Abstract nr 1943.
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abstract 1973 targeting PARG in pancreatic cancer implications for synthetic lethal therapeutic strategies
Cancer Research, 2018Co-Authors: Saswati N Chand, Dominic I James, Allan M Jordan, Kate M Smith, Annjosette Ramirez, Aditi Jain, Avinoam Nevler, Cinthya Yabarlowder, Joseph A Cozzitorto, Ian D WaddellAbstract:Metastatic pancreatic ductal adenocarcinoma (PDA) has an average survival of less than one year. There is a pressing need to identify patient subgroups for treatment with novel targeted agents and the necessity to combat increasing incidence of therapeutic resistance. In a previous study, we identified that poly(ADP) ribose glycohydrolase (PARG) is a critical player in mediating resistance to PARP inhibitor (PARPi); therefore targeting PARG is a strategy to enhance PARPi therapy in PDA and can be optimized to benefit patients with or without homologous repair (HR) deficiencies. We developed and characterized multiple PARG inhibition models in both DNA- repair proficient (MIA PaCa-2) and deficient (Hs766t) PDA lines; doxycycline-inducible shPARG knockdown, CRISPR- mediated PARG knockout and small molecule inhibition via a series of potent first-in-class, cell-active PARG inhibitors (PARGi). Our data show that PARG inhibition is synthetic lethal with DNA damage repair deficiency in PDA cells. This was further validated in isogenic colorectal cell lines with varying DNA repair functionality: DLD1 lines with BRCA2 (+/+, +/-, -/-) and RKO lines with FANCC (+/+, +/-, -/-). We have also shown that PARG inhibition enhances PARPi sensitivity through increased accumulation of DNA damage, apoptosis and persistence of detrimental PARylation. Moreover, PARP1 was trapped on the chromatin in response to both PARPi treatment as well as DNA damaging agents such as oxaliplatin. Complementary xenograft experiments were performed wherein MIA.shPARG cells were injected in nude female athymic mice. At an average tumor volume of 50mm3, respective groups were fed DOX- chow to induce PARG knockdown and treated with olaparib intraperitoneally at 100mg/kg five times a week. PARG inhibition by doxycycline induction significantly decreased tumor volumes (50% decrease, p-value 0.0165), which was further enhanced with olaparib treatment (70% decrease, p- value 0.0004), when compared with control arms. Similar results were obtained when DOX-fed mice with MIA.shPARG cells were treated with olaparib at 50mg/kg. Furthermore, in an attempt to mimic and break long-term in vivo PARPi resistance, doxycycline-mediated PARG inhibition was induced in the olaparib treatment arm on day 56 (with established tumors, and exposed to olaparib for 3weeks i.e. 15 injections). This resulted in a significant decrease in tumor volume when compared to control untreated arm (46% decrease, p-value 0.0025) and the olaparib only treatment arm (25% decrease, p-value 0.0124). We are currently validating these results in a DDR-deficient HST.shPARG cell line, as well as with CRISPR knockouts of PARG. Together these studies validate PARG as a therapeutically relevant and “druggable” target in both HR-proficient and deficient PDA cells, and lays the groundwork to optimize PARPi-based as well as other DNA targeted therapies in the treatment of PDA. Citation Format: Saswati N. Chand, AnnJosette Ramirez, Aditi Jain, Avinoam Nevler, Cinthya Yabar-Lowder, Joseph A. Cozzitorto, Dominic I. James, Allan Jordan, Kate M. Smith, Ian Waddell, Charles J. Yeo, Jordan M. Winter, Jonathan R. Brody. Targeting PARG in pancreatic cancer: Implications for synthetic lethal therapeutic strategies [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2018; 2018 Apr 14-18; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2018;78(13 Suppl):Abstract nr 1973.
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selective loss of PARG restores parylation and counteracts parp inhibitor mediated synthetic lethality
Cancer Cell, 2018Co-Authors: Ewa Gogola, Dominic I James, Alexandra A Duarte, Julian R De Ruiter, Wouter W Wiegant, Jonas A Schmid, Roebi De Bruijn, Sergi Guerrero Llobet, Daniel J Vis, Stefano AnnunziatoAbstract:Inhibitors of poly(ADP-ribose) (PAR) polymerase (PARPi) have recently entered the clinic for the treatment of homologous recombination (HR)-deficient cancers. Despite the success of this approach, drug resistance is a clinical hurdle, and we poorly understand how cancer cells escape the deadly effects of PARPi without restoring the HR pathway. By combining genetic screens with multi-omics analysis of matched PARPi-sensitive and -resistant Brca2-mutated mouse mammary tumors, we identified loss of PAR glycohydrolase (PARG) as a major resistance mechanism. We also found the presence of PARG-negative clones in a subset of human serous ovarian and triple-negative breast cancers. PARG depletion restores PAR formation and partially rescues PARP1 signaling. Importantly, PARG inactivation exposes vulnerabilities that can be exploited therapeutically.
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first in class chemical probes against poly adp ribose glycohydrolase PARG inhibit dna repair with differential pharmacology to olaparib
ACS Chemical Biology, 2016Co-Authors: Dominic I James, Allan M Jordan, Nicola Hamilton, Kate M Smith, Emma Fairweather, Colin Hutton, Louise A Griffiths, James R Hitchin, Stuart Jones, Paul P KellyAbstract:The enzyme poly(ADP-ribose) glycohydrolase (PARG) performs a critical role in the repair of DNA single strand breaks (SSBs). However, a detailed understanding of its mechanism of action has been hampered by a lack of credible, cell-active chemical probes. Herein, we demonstrate inhibition of PARG with a small molecule, leading to poly(ADP-ribose) (PAR) chain persistence in intact cells. Moreover, we describe two advanced, and chemically distinct, cell-active tool compounds with convincing on-target pharmacology and selectivity. Using one of these tool compounds, we demonstrate pharmacology consistent with PARG inhibition. Further, while the roles of PARG and poly(ADP-ribose) polymerase (PARP) are closely intertwined, we demonstrate that the pharmacology of a PARG inhibitor differs from that observed with the more thoroughly studied PARP inhibitor olaparib. We believe that these tools will facilitate a wider understanding of this important component of DNA repair and may enable the development of novel the...
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first in class chemical probes against poly adp ribose glycohydrolase PARG inhibit dna repair with differential pharmacology to olaparib
ACS Chemical Biology, 2016Co-Authors: Dominic I James, Allan M Jordan, Nicola Hamilton, Kate M Smith, Colin Hutton, Louise A Griffiths, James R Hitchin, Stuart Jones, Emma E Fairweather, Paul P KellyAbstract:The enzyme poly(ADP-ribose) glycohydrolase (PARG) performs a critical role in the repair of DNA single strand breaks (SSBs). However, a detailed understanding of its mechanism of action has been hampered by a lack of credible, cell-active chemical probes. Herein, we demonstrate inhibition of PARG with a small molecule, leading to poly(ADP-ribose) (PAR) chain persistence in intact cells. Moreover, we describe two advanced, and chemically distinct, cell-active tool compounds with convincing on-target pharmacology and selectivity. Using one of these tool compounds, we demonstrate pharmacology consistent with PARG inhibition. Further, while the roles of PARG and poly(ADP-ribose) polymerase (PARP) are closely intertwined, we demonstrate that the pharmacology of a PARG inhibitor differs from that observed with the more thoroughly studied PARP inhibitor olaparib. We believe that these tools will facilitate a wider understanding of this important component of DNA repair and may enable the development of novel therapeutic agents exploiting the critical dependence of tumors on the DNA damage response (DDR).
Allan M Jordan - One of the best experts on this subject based on the ideXlab platform.
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cell active small molecule inhibitors of the dna damage repair enzyme poly adp ribose glycohydrolase PARG discovery and optimization of orally bioavailable quinazolinedione sulfonamides
Journal of Medicinal Chemistry, 2018Co-Authors: Bohdan Waszkowycz, Allan M Jordan, Nicola Hamilton, Alison E Mcgonagle, Kate M Smith, Ben Acton, Niall M Hamilton, Louise A Griffiths, Emma E Fairweather, James R HitchinAbstract:DNA damage repair enzymes are promising targets in the development of new therapeutic agents for a wide range of cancers and potentially other diseases. The enzyme poly(ADP-ribose) glycohydrolase (PARG) plays a pivotal role in the regulation of DNA repair mechanisms; however, the lack of potent drug-like inhibitors for use in cellular and in vivo models has limited the investigation of its potential as a novel therapeutic target. Using the crystal structure of human PARG in complex with the weakly active and cytotoxic anthraquinone 8a, novel quinazolinedione sulfonamides PARG inhibitors have been identified by means of structure-based virtual screening and library design. 1-Oxetan-3-ylmethyl derivatives 33d and 35d were selected for preliminary investigations in vivo. X-ray crystal structures help rationalize the observed structure–activity relationships of these novel inhibitors.
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abstract 1943 PARG inhibitors exhibit synthetic lethality with xrcc1 deficiency and a cellular mechanism of action that is distinct from parp inhibition
Cancer Research, 2018Co-Authors: Leenus Martin, Dominic I James, Allan M Jordan, Ian D Waddell, Tzuling Cheng, Habiba Begum, Kate M Smith, Kedar S Vaidya, Marcus Fischer, Bing YaoAbstract:Poly(ADP-ribose) glycohydrolase (PARG) hydrolyzes poly(ADP-ribose) (PAR) chains that are polymerized by PARP enzymes, completing the PAR cycle. Small molecule inhibitors of PARG result in a dose dependent increase in cellular PAR after DNA damage. Here we demonstrate that depletion of XRCC1, a scaffolding protein with an essential role in base-excision repair (BER), sensitizes cancer cells to PARG inhibition. XRCC1 deficient cells exhibit increased nuclear PAR foci in response to PARG inhibition even in the absence of DNA damaging agents. Inhibition of PARP1 with RNAi or small molecule inhibitors rescues cell growth inhibition and reduces the amount of cellular PAR accumulation in PARG inhibitor treated cells. This indicates that the cellular growth inhibition is dependent upon cellular PAR levels, demonstrating selectivity of the small molecule inhibitors for PARG. We hypothesized that inhibition of PAR hydrolysis could result in depletion of cellular NAD as this could prevent recycling of PAR to NAD. Consistent with this hypothesis, PARG inhibition enhanced NAD depletion after treatment of cells with the DNA damaging agent methyl methanesulfonate (MMS). Live cell imaging of XRCC1 depleted cells treated with a PARG inhibitor revealed that cells have large membrane protrusions, similar to the morphology of cells that have been treated with a NAMPT inhibitor, which results in depletion of cellular NAD. Furthermore, addition of the NAD precursor, nicotinamide mononucleotide (NMN) rescued proliferation of PARG inhibited cells. Taken together, these data support a hypothesis in which PARG inhibitors are cytotoxic to sensitive cancer cells via depletion of NAD, ultimately starving the cell of ATP. Thus, PARG inhibition is a novel strategy for exploiting synthetic lethality in cancer cells. The defects that sensitize cancer cells to PARG inhibition are distinct from those that sensitize to PARP inhibitors, namely defects in homology directed repair. Approximately 15% of breast cancer samples exhibit low or no XRCC1 by IHC. A subset (approximately 35%) of the XRCC1 low patient samples also have defects in BRCA1, suggesting that the majority of XRCC1 low tumors may not be responsive to PARP inhibitors. Small molecule PARG inhibitors are currently being evaluated for efficacy in XRCC1 low xenograft models. Citation Format: Leenus Martin, Tzuling Cheng, Dominic I. James, Habiba Begum, Kate M. Smith, Allan Jordan, Ian Waddell, Kedar Vaidya, Marcus Fischer, Bing Yao, Jason Drummond, Leah Cleary, Ruben Martinez, James Sutton, Nandini Ravindran, James Joseph, Eleni Venetsanakos, Michael Dillon, Jeffrey H. Hager, Lisa D. Belmont. PARG inhibitors exhibit synthetic lethality with XRCC1 deficiency and a cellular mechanism of action that is distinct from PARP inhibition [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2018; 2018 Apr 14-18; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2018;78(13 Suppl):Abstract nr 1943.
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abstract 1973 targeting PARG in pancreatic cancer implications for synthetic lethal therapeutic strategies
Cancer Research, 2018Co-Authors: Saswati N Chand, Dominic I James, Allan M Jordan, Kate M Smith, Annjosette Ramirez, Aditi Jain, Avinoam Nevler, Cinthya Yabarlowder, Joseph A Cozzitorto, Ian D WaddellAbstract:Metastatic pancreatic ductal adenocarcinoma (PDA) has an average survival of less than one year. There is a pressing need to identify patient subgroups for treatment with novel targeted agents and the necessity to combat increasing incidence of therapeutic resistance. In a previous study, we identified that poly(ADP) ribose glycohydrolase (PARG) is a critical player in mediating resistance to PARP inhibitor (PARPi); therefore targeting PARG is a strategy to enhance PARPi therapy in PDA and can be optimized to benefit patients with or without homologous repair (HR) deficiencies. We developed and characterized multiple PARG inhibition models in both DNA- repair proficient (MIA PaCa-2) and deficient (Hs766t) PDA lines; doxycycline-inducible shPARG knockdown, CRISPR- mediated PARG knockout and small molecule inhibition via a series of potent first-in-class, cell-active PARG inhibitors (PARGi). Our data show that PARG inhibition is synthetic lethal with DNA damage repair deficiency in PDA cells. This was further validated in isogenic colorectal cell lines with varying DNA repair functionality: DLD1 lines with BRCA2 (+/+, +/-, -/-) and RKO lines with FANCC (+/+, +/-, -/-). We have also shown that PARG inhibition enhances PARPi sensitivity through increased accumulation of DNA damage, apoptosis and persistence of detrimental PARylation. Moreover, PARP1 was trapped on the chromatin in response to both PARPi treatment as well as DNA damaging agents such as oxaliplatin. Complementary xenograft experiments were performed wherein MIA.shPARG cells were injected in nude female athymic mice. At an average tumor volume of 50mm3, respective groups were fed DOX- chow to induce PARG knockdown and treated with olaparib intraperitoneally at 100mg/kg five times a week. PARG inhibition by doxycycline induction significantly decreased tumor volumes (50% decrease, p-value 0.0165), which was further enhanced with olaparib treatment (70% decrease, p- value 0.0004), when compared with control arms. Similar results were obtained when DOX-fed mice with MIA.shPARG cells were treated with olaparib at 50mg/kg. Furthermore, in an attempt to mimic and break long-term in vivo PARPi resistance, doxycycline-mediated PARG inhibition was induced in the olaparib treatment arm on day 56 (with established tumors, and exposed to olaparib for 3weeks i.e. 15 injections). This resulted in a significant decrease in tumor volume when compared to control untreated arm (46% decrease, p-value 0.0025) and the olaparib only treatment arm (25% decrease, p-value 0.0124). We are currently validating these results in a DDR-deficient HST.shPARG cell line, as well as with CRISPR knockouts of PARG. Together these studies validate PARG as a therapeutically relevant and “druggable” target in both HR-proficient and deficient PDA cells, and lays the groundwork to optimize PARPi-based as well as other DNA targeted therapies in the treatment of PDA. Citation Format: Saswati N. Chand, AnnJosette Ramirez, Aditi Jain, Avinoam Nevler, Cinthya Yabar-Lowder, Joseph A. Cozzitorto, Dominic I. James, Allan Jordan, Kate M. Smith, Ian Waddell, Charles J. Yeo, Jordan M. Winter, Jonathan R. Brody. Targeting PARG in pancreatic cancer: Implications for synthetic lethal therapeutic strategies [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2018; 2018 Apr 14-18; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2018;78(13 Suppl):Abstract nr 1973.
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Cell-Active Small Molecule Inhibitors of the DNA-Damage Repair Enzyme Poly(ADP-ribose) Glycohydrolase (PARG): Discovery and Optimization of Orally Bioavailable Quinazolinedione Sulfonamides
2018Co-Authors: Bohdan Waszkowycz, Allan M Jordan, Alison E Mcgonagle, Kate M Smith, Ben Acton, Niall M Hamilton, Louise A Griffiths, Emma E Fairweather, Nicola S. Hamilton, James R HitchinAbstract:DNA damage repair enzymes are promising targets in the development of new therapeutic agents for a wide range of cancers and potentially other diseases. The enzyme poly(ADP-ribose) glycohydrolase (PARG) plays a pivotal role in the regulation of DNA repair mechanisms; however, the lack of potent drug-like inhibitors for use in cellular and in vivo models has limited the investigation of its potential as a novel therapeutic target. Using the crystal structure of human PARG in complex with the weakly active and cytotoxic anthraquinone 8a, novel quinazolinedione sulfonamides PARG inhibitors have been identified by means of structure-based virtual screening and library design. 1-Oxetan-3-ylmethyl derivatives 33d and 35d were selected for preliminary investigations in vivo. X-ray crystal structures help rationalize the observed structure–activity relationships of these novel inhibitors
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first in class chemical probes against poly adp ribose glycohydrolase PARG inhibit dna repair with differential pharmacology to olaparib
ACS Chemical Biology, 2016Co-Authors: Dominic I James, Allan M Jordan, Nicola Hamilton, Kate M Smith, Emma Fairweather, Colin Hutton, Louise A Griffiths, James R Hitchin, Stuart Jones, Paul P KellyAbstract:The enzyme poly(ADP-ribose) glycohydrolase (PARG) performs a critical role in the repair of DNA single strand breaks (SSBs). However, a detailed understanding of its mechanism of action has been hampered by a lack of credible, cell-active chemical probes. Herein, we demonstrate inhibition of PARG with a small molecule, leading to poly(ADP-ribose) (PAR) chain persistence in intact cells. Moreover, we describe two advanced, and chemically distinct, cell-active tool compounds with convincing on-target pharmacology and selectivity. Using one of these tool compounds, we demonstrate pharmacology consistent with PARG inhibition. Further, while the roles of PARG and poly(ADP-ribose) polymerase (PARP) are closely intertwined, we demonstrate that the pharmacology of a PARG inhibitor differs from that observed with the more thoroughly studied PARP inhibitor olaparib. We believe that these tools will facilitate a wider understanding of this important component of DNA repair and may enable the development of novel the...
Nicola Hamilton - One of the best experts on this subject based on the ideXlab platform.
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cell active small molecule inhibitors of the dna damage repair enzyme poly adp ribose glycohydrolase PARG discovery and optimization of orally bioavailable quinazolinedione sulfonamides
Journal of Medicinal Chemistry, 2018Co-Authors: Bohdan Waszkowycz, Allan M Jordan, Nicola Hamilton, Alison E Mcgonagle, Kate M Smith, Ben Acton, Niall M Hamilton, Louise A Griffiths, Emma E Fairweather, James R HitchinAbstract:DNA damage repair enzymes are promising targets in the development of new therapeutic agents for a wide range of cancers and potentially other diseases. The enzyme poly(ADP-ribose) glycohydrolase (PARG) plays a pivotal role in the regulation of DNA repair mechanisms; however, the lack of potent drug-like inhibitors for use in cellular and in vivo models has limited the investigation of its potential as a novel therapeutic target. Using the crystal structure of human PARG in complex with the weakly active and cytotoxic anthraquinone 8a, novel quinazolinedione sulfonamides PARG inhibitors have been identified by means of structure-based virtual screening and library design. 1-Oxetan-3-ylmethyl derivatives 33d and 35d were selected for preliminary investigations in vivo. X-ray crystal structures help rationalize the observed structure–activity relationships of these novel inhibitors.
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first in class chemical probes against poly adp ribose glycohydrolase PARG inhibit dna repair with differential pharmacology to olaparib
ACS Chemical Biology, 2016Co-Authors: Dominic I James, Allan M Jordan, Nicola Hamilton, Kate M Smith, Emma Fairweather, Colin Hutton, Louise A Griffiths, James R Hitchin, Stuart Jones, Paul P KellyAbstract:The enzyme poly(ADP-ribose) glycohydrolase (PARG) performs a critical role in the repair of DNA single strand breaks (SSBs). However, a detailed understanding of its mechanism of action has been hampered by a lack of credible, cell-active chemical probes. Herein, we demonstrate inhibition of PARG with a small molecule, leading to poly(ADP-ribose) (PAR) chain persistence in intact cells. Moreover, we describe two advanced, and chemically distinct, cell-active tool compounds with convincing on-target pharmacology and selectivity. Using one of these tool compounds, we demonstrate pharmacology consistent with PARG inhibition. Further, while the roles of PARG and poly(ADP-ribose) polymerase (PARP) are closely intertwined, we demonstrate that the pharmacology of a PARG inhibitor differs from that observed with the more thoroughly studied PARP inhibitor olaparib. We believe that these tools will facilitate a wider understanding of this important component of DNA repair and may enable the development of novel the...
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first in class chemical probes against poly adp ribose glycohydrolase PARG inhibit dna repair with differential pharmacology to olaparib
ACS Chemical Biology, 2016Co-Authors: Dominic I James, Allan M Jordan, Nicola Hamilton, Kate M Smith, Colin Hutton, Louise A Griffiths, James R Hitchin, Stuart Jones, Emma E Fairweather, Paul P KellyAbstract:The enzyme poly(ADP-ribose) glycohydrolase (PARG) performs a critical role in the repair of DNA single strand breaks (SSBs). However, a detailed understanding of its mechanism of action has been hampered by a lack of credible, cell-active chemical probes. Herein, we demonstrate inhibition of PARG with a small molecule, leading to poly(ADP-ribose) (PAR) chain persistence in intact cells. Moreover, we describe two advanced, and chemically distinct, cell-active tool compounds with convincing on-target pharmacology and selectivity. Using one of these tool compounds, we demonstrate pharmacology consistent with PARG inhibition. Further, while the roles of PARG and poly(ADP-ribose) polymerase (PARP) are closely intertwined, we demonstrate that the pharmacology of a PARG inhibitor differs from that observed with the more thoroughly studied PARP inhibitor olaparib. We believe that these tools will facilitate a wider understanding of this important component of DNA repair and may enable the development of novel therapeutic agents exploiting the critical dependence of tumors on the DNA damage response (DDR).
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abstract 3714 optimisation of quinazolinedione sulphonamides as novel inhibitors of poly adp ribose glycohydrolase PARG
Cancer Research, 2016Co-Authors: Katherine Clegg Smith, Dominic I James, Allan M Jordan, Nicola Hamilton, Alison E Mcgonagle, Ben Acton, Stuart Jones, Cliff Jones, Daniel P Mould, Helen F SmallAbstract:The macrodomain protein poly(ADP ribose) glycohydrolase (PARG) has been shown to be a critical component in the repair of single stand DNA breaks and counteracts the function of the ARTD family of poly(ADP ribose) polymerases, commonly known as the PARPs. As PARG exists as a single protein, it presents an attractive target for therapeutic intervention in cancer cells with enhanced dependence upon DNA repair. Inhibitors of this enzyme have proved difficult to discover and develop. Moreover, intact cell-active tool compounds which have the propensity to be used as robust chemical probes to understand PARG pharmacology, are absent from the literature. This poster will describe our work in this emerging area, optimising a series of drug-like quinazolinedione derivatives to deliver molecules with the correct physicochemical and biochemical properties to function as in vitro cell probe compounds. These unprecedented agents display potent on-target biochemical (5 nM) and cell (10 nM) activity with a significant window to acute 3-day cytotoxicity. Moreover, these agents are selective against PARP family members and the close glycohydrolase homologue ARH3. The medicinal chemistry optimisation of the scaffold will be described, alongside the outline pharmacology demonstrating on-target, selective inhibition of PARG in cells. Such tool compounds will be of value in revealing the detailed mechanisms of action of PARG in DNA repair and other PAR chain-mediated cellular processes, with the ultimate goal of delivering novel and clinically relevant therapeutic agents. Citation Format: Kate Smith, Ben Acton, Dominic James, Cliff Jones, Stuart Jones, Allan Jordan, Nicola Hamilton, Alison McGonagle, Daniel Mould, Helen Small, Alex Stowell, Julie Tucker, Ian Waddell, Bohdan Waszkowycz, Donald Ogilvie. Optimisation of quinazolinedione sulphonamides as novel inhibitors of poly(ADP Ribose) glycohydrolase (PARG). [abstract]. In: Proceedings of the 107th Annual Meeting of the American Association for Cancer Research; 2016 Apr 16-20; New Orleans, LA. Philadelphia (PA): AACR; Cancer Res 2016;76(14 Suppl):Abstract nr 3714.
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abstract 3715 benzimidazolone sulphonamides potent selective and drug like inhibitors of poly adp ribose glycohydrolase PARG
Cancer Research, 2016Co-Authors: Allan M Jordan, Dominic I James, Nicola Hamilton, Alison E Mcgonagle, Ben Acton, Colin Hutton, James R Hitchin, Stuart Jones, Cliff Jones, Helen F SmallAbstract:In recent years, many proteins involved in DNA repair, such as ATR, ATM and PARP, have received considerable attention as potential points of therapeutic intervention in cancer. Indeed, these efforts have recently delivered several agents into clinical evaluation or FDA regulatory approval. However, the DNA repair protein poly(ADP ribose) glycohydrolase (PARG), which plays an equally critical role in DNA single stand break repair, to successful drug discovery efforts. Through our innovative collaboration with AstraZeneca, we have discovered a novel PARG-binding pharmacophore and have employed this information to discover drug-like chemotypes, facilitating the development of potent and selective inhibitors. This poster will describe our emerging results in this area, where a novel benzimidazolone sulphonamide scaffold has been shown potently to inhibit PARG in both biochemical and cellular assays with potencies of 40 nM and 60 nM respectively. Moreover, these agents display pharmacology consistent with the anticipated mode of action, appropriate drug-like properties and are selective against PARP1 and the close glycohydrolase homologue ARH3. The medicinal chemistry optimisation of this scaffold will be described, alongside the recent biological results obtained. Ultimately, this work has helped deliver tool compounds which may help to elucidate the true pharmacology and roles of PARG in cancer and other disease settings. Citation Format: Allan Jordan, Ben Acton, Nicola Hamilton, James Hitchin, Colin Hutton, Dominic James, Cliff Jones, Stuart Jones, Alison McGonagle, Helen Small, Kate Smith, Alex Stowell, Julie Tucker, Ian Waddell, Bohdan Waszkowycz, Donald Ogilvie. Benzimidazolone sulphonamides - potent, selective and drug-like inhibitors of poly(ADP Ribose) Glycohydrolase (PARG). [abstract]. In: Proceedings of the 107th Annual Meeting of the American Association for Cancer Research; 2016 Apr 16-20; New Orleans, LA. Philadelphia (PA): AACR; Cancer Res 2016;76(14 Suppl):Abstract nr 3715.
James R Hitchin - One of the best experts on this subject based on the ideXlab platform.
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cell active small molecule inhibitors of the dna damage repair enzyme poly adp ribose glycohydrolase PARG discovery and optimization of orally bioavailable quinazolinedione sulfonamides
Journal of Medicinal Chemistry, 2018Co-Authors: Bohdan Waszkowycz, Allan M Jordan, Nicola Hamilton, Alison E Mcgonagle, Kate M Smith, Ben Acton, Niall M Hamilton, Louise A Griffiths, Emma E Fairweather, James R HitchinAbstract:DNA damage repair enzymes are promising targets in the development of new therapeutic agents for a wide range of cancers and potentially other diseases. The enzyme poly(ADP-ribose) glycohydrolase (PARG) plays a pivotal role in the regulation of DNA repair mechanisms; however, the lack of potent drug-like inhibitors for use in cellular and in vivo models has limited the investigation of its potential as a novel therapeutic target. Using the crystal structure of human PARG in complex with the weakly active and cytotoxic anthraquinone 8a, novel quinazolinedione sulfonamides PARG inhibitors have been identified by means of structure-based virtual screening and library design. 1-Oxetan-3-ylmethyl derivatives 33d and 35d were selected for preliminary investigations in vivo. X-ray crystal structures help rationalize the observed structure–activity relationships of these novel inhibitors.
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Cell-Active Small Molecule Inhibitors of the DNA-Damage Repair Enzyme Poly(ADP-ribose) Glycohydrolase (PARG): Discovery and Optimization of Orally Bioavailable Quinazolinedione Sulfonamides
2018Co-Authors: Bohdan Waszkowycz, Allan M Jordan, Alison E Mcgonagle, Kate M Smith, Ben Acton, Niall M Hamilton, Louise A Griffiths, Emma E Fairweather, Nicola S. Hamilton, James R HitchinAbstract:DNA damage repair enzymes are promising targets in the development of new therapeutic agents for a wide range of cancers and potentially other diseases. The enzyme poly(ADP-ribose) glycohydrolase (PARG) plays a pivotal role in the regulation of DNA repair mechanisms; however, the lack of potent drug-like inhibitors for use in cellular and in vivo models has limited the investigation of its potential as a novel therapeutic target. Using the crystal structure of human PARG in complex with the weakly active and cytotoxic anthraquinone 8a, novel quinazolinedione sulfonamides PARG inhibitors have been identified by means of structure-based virtual screening and library design. 1-Oxetan-3-ylmethyl derivatives 33d and 35d were selected for preliminary investigations in vivo. X-ray crystal structures help rationalize the observed structure–activity relationships of these novel inhibitors
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first in class chemical probes against poly adp ribose glycohydrolase PARG inhibit dna repair with differential pharmacology to olaparib
ACS Chemical Biology, 2016Co-Authors: Dominic I James, Allan M Jordan, Nicola Hamilton, Kate M Smith, Emma Fairweather, Colin Hutton, Louise A Griffiths, James R Hitchin, Stuart Jones, Paul P KellyAbstract:The enzyme poly(ADP-ribose) glycohydrolase (PARG) performs a critical role in the repair of DNA single strand breaks (SSBs). However, a detailed understanding of its mechanism of action has been hampered by a lack of credible, cell-active chemical probes. Herein, we demonstrate inhibition of PARG with a small molecule, leading to poly(ADP-ribose) (PAR) chain persistence in intact cells. Moreover, we describe two advanced, and chemically distinct, cell-active tool compounds with convincing on-target pharmacology and selectivity. Using one of these tool compounds, we demonstrate pharmacology consistent with PARG inhibition. Further, while the roles of PARG and poly(ADP-ribose) polymerase (PARP) are closely intertwined, we demonstrate that the pharmacology of a PARG inhibitor differs from that observed with the more thoroughly studied PARP inhibitor olaparib. We believe that these tools will facilitate a wider understanding of this important component of DNA repair and may enable the development of novel the...
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first in class chemical probes against poly adp ribose glycohydrolase PARG inhibit dna repair with differential pharmacology to olaparib
ACS Chemical Biology, 2016Co-Authors: Dominic I James, Allan M Jordan, Nicola Hamilton, Kate M Smith, Colin Hutton, Louise A Griffiths, James R Hitchin, Stuart Jones, Emma E Fairweather, Paul P KellyAbstract:The enzyme poly(ADP-ribose) glycohydrolase (PARG) performs a critical role in the repair of DNA single strand breaks (SSBs). However, a detailed understanding of its mechanism of action has been hampered by a lack of credible, cell-active chemical probes. Herein, we demonstrate inhibition of PARG with a small molecule, leading to poly(ADP-ribose) (PAR) chain persistence in intact cells. Moreover, we describe two advanced, and chemically distinct, cell-active tool compounds with convincing on-target pharmacology and selectivity. Using one of these tool compounds, we demonstrate pharmacology consistent with PARG inhibition. Further, while the roles of PARG and poly(ADP-ribose) polymerase (PARP) are closely intertwined, we demonstrate that the pharmacology of a PARG inhibitor differs from that observed with the more thoroughly studied PARP inhibitor olaparib. We believe that these tools will facilitate a wider understanding of this important component of DNA repair and may enable the development of novel therapeutic agents exploiting the critical dependence of tumors on the DNA damage response (DDR).
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abstract 3715 benzimidazolone sulphonamides potent selective and drug like inhibitors of poly adp ribose glycohydrolase PARG
Cancer Research, 2016Co-Authors: Allan M Jordan, Dominic I James, Nicola Hamilton, Alison E Mcgonagle, Ben Acton, Colin Hutton, James R Hitchin, Stuart Jones, Cliff Jones, Helen F SmallAbstract:In recent years, many proteins involved in DNA repair, such as ATR, ATM and PARP, have received considerable attention as potential points of therapeutic intervention in cancer. Indeed, these efforts have recently delivered several agents into clinical evaluation or FDA regulatory approval. However, the DNA repair protein poly(ADP ribose) glycohydrolase (PARG), which plays an equally critical role in DNA single stand break repair, to successful drug discovery efforts. Through our innovative collaboration with AstraZeneca, we have discovered a novel PARG-binding pharmacophore and have employed this information to discover drug-like chemotypes, facilitating the development of potent and selective inhibitors. This poster will describe our emerging results in this area, where a novel benzimidazolone sulphonamide scaffold has been shown potently to inhibit PARG in both biochemical and cellular assays with potencies of 40 nM and 60 nM respectively. Moreover, these agents display pharmacology consistent with the anticipated mode of action, appropriate drug-like properties and are selective against PARP1 and the close glycohydrolase homologue ARH3. The medicinal chemistry optimisation of this scaffold will be described, alongside the recent biological results obtained. Ultimately, this work has helped deliver tool compounds which may help to elucidate the true pharmacology and roles of PARG in cancer and other disease settings. Citation Format: Allan Jordan, Ben Acton, Nicola Hamilton, James Hitchin, Colin Hutton, Dominic James, Cliff Jones, Stuart Jones, Alison McGonagle, Helen Small, Kate Smith, Alex Stowell, Julie Tucker, Ian Waddell, Bohdan Waszkowycz, Donald Ogilvie. Benzimidazolone sulphonamides - potent, selective and drug-like inhibitors of poly(ADP Ribose) Glycohydrolase (PARG). [abstract]. In: Proceedings of the 107th Annual Meeting of the American Association for Cancer Research; 2016 Apr 16-20; New Orleans, LA. Philadelphia (PA): AACR; Cancer Res 2016;76(14 Suppl):Abstract nr 3715.
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cell active small molecule inhibitors of the dna damage repair enzyme poly adp ribose glycohydrolase PARG discovery and optimization of orally bioavailable quinazolinedione sulfonamides
Journal of Medicinal Chemistry, 2018Co-Authors: Bohdan Waszkowycz, Allan M Jordan, Nicola Hamilton, Alison E Mcgonagle, Kate M Smith, Ben Acton, Niall M Hamilton, Louise A Griffiths, Emma E Fairweather, James R HitchinAbstract:DNA damage repair enzymes are promising targets in the development of new therapeutic agents for a wide range of cancers and potentially other diseases. The enzyme poly(ADP-ribose) glycohydrolase (PARG) plays a pivotal role in the regulation of DNA repair mechanisms; however, the lack of potent drug-like inhibitors for use in cellular and in vivo models has limited the investigation of its potential as a novel therapeutic target. Using the crystal structure of human PARG in complex with the weakly active and cytotoxic anthraquinone 8a, novel quinazolinedione sulfonamides PARG inhibitors have been identified by means of structure-based virtual screening and library design. 1-Oxetan-3-ylmethyl derivatives 33d and 35d were selected for preliminary investigations in vivo. X-ray crystal structures help rationalize the observed structure–activity relationships of these novel inhibitors.
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abstract 1943 PARG inhibitors exhibit synthetic lethality with xrcc1 deficiency and a cellular mechanism of action that is distinct from parp inhibition
Cancer Research, 2018Co-Authors: Leenus Martin, Dominic I James, Allan M Jordan, Ian D Waddell, Tzuling Cheng, Habiba Begum, Kate M Smith, Kedar S Vaidya, Marcus Fischer, Bing YaoAbstract:Poly(ADP-ribose) glycohydrolase (PARG) hydrolyzes poly(ADP-ribose) (PAR) chains that are polymerized by PARP enzymes, completing the PAR cycle. Small molecule inhibitors of PARG result in a dose dependent increase in cellular PAR after DNA damage. Here we demonstrate that depletion of XRCC1, a scaffolding protein with an essential role in base-excision repair (BER), sensitizes cancer cells to PARG inhibition. XRCC1 deficient cells exhibit increased nuclear PAR foci in response to PARG inhibition even in the absence of DNA damaging agents. Inhibition of PARP1 with RNAi or small molecule inhibitors rescues cell growth inhibition and reduces the amount of cellular PAR accumulation in PARG inhibitor treated cells. This indicates that the cellular growth inhibition is dependent upon cellular PAR levels, demonstrating selectivity of the small molecule inhibitors for PARG. We hypothesized that inhibition of PAR hydrolysis could result in depletion of cellular NAD as this could prevent recycling of PAR to NAD. Consistent with this hypothesis, PARG inhibition enhanced NAD depletion after treatment of cells with the DNA damaging agent methyl methanesulfonate (MMS). Live cell imaging of XRCC1 depleted cells treated with a PARG inhibitor revealed that cells have large membrane protrusions, similar to the morphology of cells that have been treated with a NAMPT inhibitor, which results in depletion of cellular NAD. Furthermore, addition of the NAD precursor, nicotinamide mononucleotide (NMN) rescued proliferation of PARG inhibited cells. Taken together, these data support a hypothesis in which PARG inhibitors are cytotoxic to sensitive cancer cells via depletion of NAD, ultimately starving the cell of ATP. Thus, PARG inhibition is a novel strategy for exploiting synthetic lethality in cancer cells. The defects that sensitize cancer cells to PARG inhibition are distinct from those that sensitize to PARP inhibitors, namely defects in homology directed repair. Approximately 15% of breast cancer samples exhibit low or no XRCC1 by IHC. A subset (approximately 35%) of the XRCC1 low patient samples also have defects in BRCA1, suggesting that the majority of XRCC1 low tumors may not be responsive to PARP inhibitors. Small molecule PARG inhibitors are currently being evaluated for efficacy in XRCC1 low xenograft models. Citation Format: Leenus Martin, Tzuling Cheng, Dominic I. James, Habiba Begum, Kate M. Smith, Allan Jordan, Ian Waddell, Kedar Vaidya, Marcus Fischer, Bing Yao, Jason Drummond, Leah Cleary, Ruben Martinez, James Sutton, Nandini Ravindran, James Joseph, Eleni Venetsanakos, Michael Dillon, Jeffrey H. Hager, Lisa D. Belmont. PARG inhibitors exhibit synthetic lethality with XRCC1 deficiency and a cellular mechanism of action that is distinct from PARP inhibition [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2018; 2018 Apr 14-18; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2018;78(13 Suppl):Abstract nr 1943.
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abstract 1973 targeting PARG in pancreatic cancer implications for synthetic lethal therapeutic strategies
Cancer Research, 2018Co-Authors: Saswati N Chand, Dominic I James, Allan M Jordan, Kate M Smith, Annjosette Ramirez, Aditi Jain, Avinoam Nevler, Cinthya Yabarlowder, Joseph A Cozzitorto, Ian D WaddellAbstract:Metastatic pancreatic ductal adenocarcinoma (PDA) has an average survival of less than one year. There is a pressing need to identify patient subgroups for treatment with novel targeted agents and the necessity to combat increasing incidence of therapeutic resistance. In a previous study, we identified that poly(ADP) ribose glycohydrolase (PARG) is a critical player in mediating resistance to PARP inhibitor (PARPi); therefore targeting PARG is a strategy to enhance PARPi therapy in PDA and can be optimized to benefit patients with or without homologous repair (HR) deficiencies. We developed and characterized multiple PARG inhibition models in both DNA- repair proficient (MIA PaCa-2) and deficient (Hs766t) PDA lines; doxycycline-inducible shPARG knockdown, CRISPR- mediated PARG knockout and small molecule inhibition via a series of potent first-in-class, cell-active PARG inhibitors (PARGi). Our data show that PARG inhibition is synthetic lethal with DNA damage repair deficiency in PDA cells. This was further validated in isogenic colorectal cell lines with varying DNA repair functionality: DLD1 lines with BRCA2 (+/+, +/-, -/-) and RKO lines with FANCC (+/+, +/-, -/-). We have also shown that PARG inhibition enhances PARPi sensitivity through increased accumulation of DNA damage, apoptosis and persistence of detrimental PARylation. Moreover, PARP1 was trapped on the chromatin in response to both PARPi treatment as well as DNA damaging agents such as oxaliplatin. Complementary xenograft experiments were performed wherein MIA.shPARG cells were injected in nude female athymic mice. At an average tumor volume of 50mm3, respective groups were fed DOX- chow to induce PARG knockdown and treated with olaparib intraperitoneally at 100mg/kg five times a week. PARG inhibition by doxycycline induction significantly decreased tumor volumes (50% decrease, p-value 0.0165), which was further enhanced with olaparib treatment (70% decrease, p- value 0.0004), when compared with control arms. Similar results were obtained when DOX-fed mice with MIA.shPARG cells were treated with olaparib at 50mg/kg. Furthermore, in an attempt to mimic and break long-term in vivo PARPi resistance, doxycycline-mediated PARG inhibition was induced in the olaparib treatment arm on day 56 (with established tumors, and exposed to olaparib for 3weeks i.e. 15 injections). This resulted in a significant decrease in tumor volume when compared to control untreated arm (46% decrease, p-value 0.0025) and the olaparib only treatment arm (25% decrease, p-value 0.0124). We are currently validating these results in a DDR-deficient HST.shPARG cell line, as well as with CRISPR knockouts of PARG. Together these studies validate PARG as a therapeutically relevant and “druggable” target in both HR-proficient and deficient PDA cells, and lays the groundwork to optimize PARPi-based as well as other DNA targeted therapies in the treatment of PDA. Citation Format: Saswati N. Chand, AnnJosette Ramirez, Aditi Jain, Avinoam Nevler, Cinthya Yabar-Lowder, Joseph A. Cozzitorto, Dominic I. James, Allan Jordan, Kate M. Smith, Ian Waddell, Charles J. Yeo, Jordan M. Winter, Jonathan R. Brody. Targeting PARG in pancreatic cancer: Implications for synthetic lethal therapeutic strategies [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2018; 2018 Apr 14-18; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2018;78(13 Suppl):Abstract nr 1973.
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Cell-Active Small Molecule Inhibitors of the DNA-Damage Repair Enzyme Poly(ADP-ribose) Glycohydrolase (PARG): Discovery and Optimization of Orally Bioavailable Quinazolinedione Sulfonamides
2018Co-Authors: Bohdan Waszkowycz, Allan M Jordan, Alison E Mcgonagle, Kate M Smith, Ben Acton, Niall M Hamilton, Louise A Griffiths, Emma E Fairweather, Nicola S. Hamilton, James R HitchinAbstract:DNA damage repair enzymes are promising targets in the development of new therapeutic agents for a wide range of cancers and potentially other diseases. The enzyme poly(ADP-ribose) glycohydrolase (PARG) plays a pivotal role in the regulation of DNA repair mechanisms; however, the lack of potent drug-like inhibitors for use in cellular and in vivo models has limited the investigation of its potential as a novel therapeutic target. Using the crystal structure of human PARG in complex with the weakly active and cytotoxic anthraquinone 8a, novel quinazolinedione sulfonamides PARG inhibitors have been identified by means of structure-based virtual screening and library design. 1-Oxetan-3-ylmethyl derivatives 33d and 35d were selected for preliminary investigations in vivo. X-ray crystal structures help rationalize the observed structure–activity relationships of these novel inhibitors
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first in class chemical probes against poly adp ribose glycohydrolase PARG inhibit dna repair with differential pharmacology to olaparib
ACS Chemical Biology, 2016Co-Authors: Dominic I James, Allan M Jordan, Nicola Hamilton, Kate M Smith, Emma Fairweather, Colin Hutton, Louise A Griffiths, James R Hitchin, Stuart Jones, Paul P KellyAbstract:The enzyme poly(ADP-ribose) glycohydrolase (PARG) performs a critical role in the repair of DNA single strand breaks (SSBs). However, a detailed understanding of its mechanism of action has been hampered by a lack of credible, cell-active chemical probes. Herein, we demonstrate inhibition of PARG with a small molecule, leading to poly(ADP-ribose) (PAR) chain persistence in intact cells. Moreover, we describe two advanced, and chemically distinct, cell-active tool compounds with convincing on-target pharmacology and selectivity. Using one of these tool compounds, we demonstrate pharmacology consistent with PARG inhibition. Further, while the roles of PARG and poly(ADP-ribose) polymerase (PARP) are closely intertwined, we demonstrate that the pharmacology of a PARG inhibitor differs from that observed with the more thoroughly studied PARP inhibitor olaparib. We believe that these tools will facilitate a wider understanding of this important component of DNA repair and may enable the development of novel the...