Inhibition of poly(ADP-ribose) glycohydrolase (PARG) specifically kills BRCA2-deficient tumor cells

Fathers, Catherine; Drayton, Ross M.; Solovieva, S. E.; Bryant, Helen E.

doi:10.4161/cc.11.5.19482

Cited by 81 publications

(91 citation statements)

References 50 publications

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“…Our immunofluorescence (IF)-based confocal imaging experiments confirmed our results (Fig. 1E) and the previously reported accumulation of ␥H2AX foci in unperturbed PARG-depleted cells (23) (Fig. 4A).…”

Section: Resultssupporting

confidence: 81%

“…In this scenario, upon PARG depletion and reversed fork accumulation, HR and other DSB repair factors may become essential to drive alternative, RecQ1-independent pathways for the restart of reversed replication forks. This may provide an alternative explanation for the reported requirement of HR for cell survival upon PARG inhibition (23). Detection of ssDNA gaps has been linked in model systems to repriming events across DNA lesions (36,37).…”

Section: Discussionmentioning

confidence: 99%

“…PARG inhibition was shown to kill homologous recombination (HR)-defective cells, via a replication-dependent mechanism (23). Although the effect of PARG inhibition on the replication process was not directly investigated, the authors postulated that replication fork collapse by PARG inhibition may lead to DSB formation and thus the HR requirement to restart collapsed forks.…”

Section: Discussionmentioning

confidence: 99%

“…Accordingly, PARG is recruited to DNA repair sites through PARP-and PCNA-dependent pathways (20,21) and prevents mitotic catastrophe upon treatments with ionizing irradiation (22). It was also reported recently that BRCA2-deficient cells are exquisitely sensitive to PARG inhibition, suggesting that PARG functionally assists PARPs in preventing deleterious events at the replication fork (23). However, the molecular mechanisms underlying PARG involvement in DNA rep-lication and repair have remained elusive, limiting also the possible clinical applications of PARG inactivation in cancer therapy.…”

mentioning

confidence: 99%

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Poly(ADP-Ribosyl) Glycohydrolase Prevents the Accumulation of Unusual Replication Structures during Unperturbed S Phase

Chaudhuri

Ahuja

Herrador

et al. 2015

Molecular and Cellular Biology

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Poly(ADP-ribosyl)ation (PAR) has been implicated in various aspects of the cellular response to DNA damage and genome stability. Although 17 human poly(ADP-ribose) polymerase (PARP) genes have been identified, a single poly(ADP-ribosyl) glycohydrolase (PARG) mediates PAR degradation. Here we investigated the role of PARG in the replication of human chromosomes. We show that PARG depletion affects cell proliferation and DNA synthesis, leading to replication-coupled H2AX phosphorylation. Furthermore, PARG depletion or inhibition per se slows down individual replication forks similarly to mild chemotherapeutic treatment. Electron microscopic analysis of replication intermediates reveals marked accumulation of reversed forks and single-stranded DNA (ssDNA) gaps in unperturbed PARG-defective cells. Intriguingly, while we found no physical evidence for chromosomal breakage, PARG-defective cells displayed both ataxia-telangiectasia-mutated (ATM) and ataxia-Rad3-related (ATR) activation, as well as chromatin recruitment of standard double-strand-break-repair factors, such as 53BP1 and RAD51. Overall, these data prove PAR degradation to be essential to promote resumption of replication at endogenous and exogenous lesions, preventing idle recruitment of repair factors to remodeled replication forks. Furthermore, they suggest that fork remodeling and restarting are surprisingly frequent in unperturbed cells and provide a molecular rationale to explore PARG inhibition in cancer chemotherapy.C ellular responses are crucial for the adaptability and survival of a cell exposed to different types of endogenous and exogenous stress. The DNA damage response (DDR) consists of one such defense mechanism in response to different types of insults to the DNA. Poly(ADP)ribosylation of proteins is one of the quickest cellular responses to DNA damage and is brought about by proteins of the poly(ADP) ribose polymerase family (PARP), mostly PARP1 (1). Upon being recruited to sites of the DNA damage, NAD ϩ is used as a substrate by PARP to synthesize negatively charged poly(ADP-ribosyl)ation (PAR) polymers onto itself and also its target proteins (1). Through this posttranslational modification, PARP targets a variety of nuclear proteins to facilitate the recruitment of DNA repair factors to sites of damage (2, 3). Accordingly, PARP-1 or PARP-2-deficient mice and mouse embryonic fibroblasts show chromosomal aberrations and various DNA repair defects (4-6).Inhibition of PARP has become a promising therapeutic approach for the treatment of certain types of cancer (7). It was shown that PARP inhibitors could selectively kill homologous recombination (HR)-deficient cancer cells (8, 9). The reason behind the sensitivity of HR-deficient cells to PARP inhibition is thought to be the accumulation of single-stranded DNA (ssDNA) breaks in the absence of PAR synthesis, leading to replication fork collapse and double-stranded breaks (DSBs), which would then require HR factors for repair (8,10). Recently, PARP activity has also been reported to play a ro...

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Section: Resultssupporting

confidence: 81%

Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

mentioning

confidence: 99%

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Poly(ADP-Ribosyl) Glycohydrolase Prevents the Accumulation of Unusual Replication Structures during Unperturbed S Phase

Chaudhuri

Ahuja

Herrador

et al. 2015

Molecular and Cellular Biology

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“…3C). Moreover, with the treatment of gallotannin (GLTN), a cell-permeable PARG inhibitor (Ying et al 2001;Fathers et al 2012), to suppress PARG-dependent PAR hydrolysis, the half-life of PAR at DNA damage sites was significantly prolonged (Supplemental Fig. 7C).…”

Section: Computational Analysis Of the Par-binding Pockets In The Fhamentioning

confidence: 99%

The FHA and BRCT domains recognize ADP-ribosylation during DNA damage response

et al. 2013

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Poly-ADP-ribosylation is a unique post-translational modification participating in many biological processes, such as DNA damage response. Here, we demonstrate that a set of Forkhead-associated (FHA) and BRCA1 C-terminal (BRCT) domains recognizes poly(ADP-ribose) (PAR) both in vitro and in vivo. Among these FHA and BRCT domains, the FHA domains of APTX and PNKP interact with iso-ADP-ribose, the linkage of PAR, whereas the BRCT domains of Ligase4, XRCC1, and NBS1 recognize ADP-ribose, the basic unit of PAR. The interactions between PAR and the FHA or BRCT domains mediate the relocation of these domain-containing proteins to DNA damage sites and facilitate the DNA damage response. Moreover, the interaction between PAR and the NBS1 BRCT domain is important for the early activation of ATM during DNA damage response and ATM-dependent cell cycle checkpoint activation. Taken together, our results demonstrate two novel PAR-binding modules that play important roles in DNA damage response.

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Genomic and biological aspects of resistance to selective poly(ADP‐ribose) glycohydrolase inhibitor PDD00017273 in human colorectal cancer cells

et al. 2022

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Background: Poly(ADP-ribose) glycohydrolase (PARG) is a key enzyme in poly(ADPribose) (PAR) metabolism and a potential anticancer target. Many drug candidates have been developed to inhibit its enzymatic activity. Additionally, PDD00017273 is an effective and selective inhibitor of PARG at the first cellular level.Aims: Using human colorectal cancer (CRC) HCT116 cells, we investigated the molecular mechanisms and tumor biological aspects of the resistance to PDD00017273.Methods and results: HCT116R PDD , a variant of the human CRC cell line HCT116, exhibits resistance to the PARG inhibitor PDD00017273. HCT116R PDD cells contained specific mutations of PARG and PARP1, namely, PARG mutation Glu352Gln and PARP1 mutation Lys134Asn, as revealed by exome sequencing. Notably, the levels of PARG protein were comparable between HCT116R PDD and HCT116. In contrast, the PARP1 protein levels in HCT116R PDD were significantly lower than those in HCT116. Consequently, the levels of intracellular poly(ADP-ribosyl)ation were elevated in HCT116R PDD compared to HCT116. Interestingly, HCT116R PDD cells did not exhibit cross-resistance to COH34, an additional PARG inhibitor. Conclusion:Our findings suggest that the mutated PARG acquires PDD00017273 resistance due to structural modifications. In addition, our findings indicate that PDD00017273 resistance induces mutation and PARP downregulation. These discoveries collectively provide a better understanding of the anticancer candidate PARG inhibitors in terms of resistance mechanisms and anticancer strategies.

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Inhibition of poly(ADP-ribose) glycohydrolase (PARG) specifically kills BRCA2-deficient tumor cells

Cited by 81 publications

References 50 publications

Poly(ADP-Ribosyl) Glycohydrolase Prevents the Accumulation of Unusual Replication Structures during Unperturbed S Phase

Poly(ADP-Ribosyl) Glycohydrolase Prevents the Accumulation of Unusual Replication Structures during Unperturbed S Phase

The FHA and BRCT domains recognize ADP-ribosylation during DNA damage response

Genomic and biological aspects of resistance to selective poly(ADP‐ribose) glycohydrolase inhibitor PDD00017273 in human colorectal cancer cells

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