Design, Synthesis, and Evaluation of New Quinazolinone Derivatives that Inhibit Bloom Syndrome Protein (BLM) Helicase, Trigger DNA Damage at the Telomere Region, and Synergize with PARP Inhibitors

Cellular innate immune sensors of DNA are essential for host defense against invading pathogens. However, the presence of self-DNA inside cells poses a risk of triggering unchecked immune responses. The mechanisms limiting induction of inflammation by self-DNA are poorly understood. BLM RecQ–like helicase is essential for genome integrity and is deficient in Bloom syndrome (BS), a rare genetic disease characterized by genome instability, accumulation of micronuclei, susceptibility to cancer, and immunodeficiency. Here, we show that BLM-deficient fibroblasts show constitutive up-regulation of inflammatory interferon-stimulated gene (ISG) expression, which is mediated by the cGAS–STING–IRF3 cytosolic DNA–sensing pathway. Increased DNA damage or down-regulation of the cytoplasmic exonuclease TREX1 enhances ISG expression in BLM-deficient fibroblasts. cGAS-containing cytoplasmic micronuclei are increased in BS cells. Finally, BS patients demonstrate elevated ISG expression in peripheral blood. These results reveal that BLM limits ISG induction, thus connecting DNA damage to cellular innate immune response, which may contribute to human pathogenesis.

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Selective Cleavage of BLM, the Bloom Syndrome Protein, during Apoptotic Cell Death

Journal of Biological Chemistry ◽

10.1074/jbc.m006462200 ◽

2001 ◽

Vol 276 (15) ◽

pp. 12068-12075 ◽

Cited By ~ 14

Author(s):

Oliver Bischof ◽

Sanjeev Galande ◽

Farzin Farzaneh ◽

Terumi Kohwi-Shigematsu ◽

Judith Campisi

Keyword(s):

Caspase 3 ◽

Apoptotic Cell ◽

Autosomal Recessive Disorder ◽

Bloom Syndrome ◽

Recognition Sequence ◽

Blm Helicase ◽

Caspase 6 ◽

Syndrome Protein ◽

Condensed Dna

Bloom syndrome (BS) is an autosomal recessive disorder characterized by a high incidence of cancer and genomic instability. BLM, the protein defective in BS, is a RECQ-like helicase that is presumed to function in mammalian DNA replication, recombination, or repair. We show here that BLM, but not the related RECQ-like helicase WRN, is rapidly cleaved in cells undergoing apoptosis. BLM was cleaved to 47- and 110-kDa major fragments, with kinetics similar to the apoptotic cleavage of poly(A)DP-ribose polymerase. BLM cleavage was prevented by a caspase 3 inhibitor and did not occur in caspase 3-deficient cells. Moreover, recombinant BLM was cleaved to 47- and 110-kDa fragments by caspase 3, but not caspase 6,in vitro. The caspase 3 recognition sequence412TEVD415was verified by mutating aspartate 415 to glycine and showing that this mutation rendered BLM resistant to caspase 3 cleavage. Cleavage did not abolish the BLM helicase activity but abolished BLM nuclear foci and the association of BLM with condensed DNA and the insoluble matrix. The results suggest that BLM, but not WRN, is an early selected target during the execution of apoptosis.

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Regulation and Localization of the Bloom Syndrome Protein in Response to DNA Damage

The Journal of Cell Biology ◽

10.1083/jcb.153.2.367 ◽

2001 ◽

Vol 153 (2) ◽

pp. 367-380 ◽

Cited By ~ 173

Author(s):

Oliver Bischof ◽

Sahn-Ho Kim ◽

John Irving ◽

Sergey Beresten ◽

Nathan A. Ellis ◽

...

Keyword(s):

Dna Damage ◽

Nuclear Matrix ◽

Autosomal Recessive Disorder ◽

Bloom Syndrome ◽

Nuclear Bodies ◽

Strand Breaks ◽

Pml Nuclear Bodies ◽

Radiation Induced ◽

Syndrome Protein ◽

G2 Delay

Bloom syndrome (BS) is an autosomal recessive disorder characterized by a high incidence of cancer and genomic instability. BLM, the protein defective in BS, is a RecQ-like helicase, presumed to function in DNA replication, recombination, or repair. BLM localizes to promyelocytic leukemia protein (PML) nuclear bodies and is expressed during late S and G2. We show, in normal human cells, that the recombination/repair proteins hRAD51 and replication protein (RP)-A assembled with BLM into a fraction of PML bodies during late S/G2. Biochemical experiments suggested that BLM resides in a nuclear matrix–bound complex in which association with hRAD51 may be direct. DNA-damaging agents that cause double strand breaks and a G2 delay induced BLM by a p53- and ataxia-telangiectasia mutated independent mechanism. This induction depended on the G2 delay, because it failed to occur when G2 was prevented or bypassed. It coincided with the appearance of foci containing BLM, PML, hRAD51 and RP-A, which resembled ionizing radiation-induced foci. After radiation, foci containing BLM and PML formed at sites of single-stranded DNA and presumptive repair in normal cells, but not in cells with defective PML. Our findings suggest that BLM is part of a dynamic nuclear matrix–based complex that requires PML and functions during G2 in undamaged cells and recombinational repair after DNA damage.

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Faculty Opinions recommendation of Intra-nuclear trafficking of the BLM helicase to DNA damage-induced foci is regulated by SUMO modification.

Faculty Opinions – Post-Publication Peer Review of the Biomedical Literature ◽

10.3410/f.1010165.322922 ◽

2005 ◽

Author(s):

Igor Stagljar

Keyword(s):

Dna Damage ◽

Nuclear Trafficking ◽

Sumo Modification ◽

Blm Helicase

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Faculty Opinions recommendation of The RIDDLE syndrome protein mediates a ubiquitin-dependent signaling cascade at sites of DNA damage.

Faculty Opinions – Post-Publication Peer Review of the Biomedical Literature ◽

10.3410/f.1157080.620928 ◽

2009 ◽

Author(s):

René Medema

Keyword(s):

Dna Damage ◽

Signaling Cascade ◽

Syndrome Protein

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Acceleration or Brakes: Which Is Rational for Cell Cycle-Targeting Neuroblastoma Therapy?

Biomolecules ◽

10.3390/biom11050750 ◽

2021 ◽

Vol 11 (5) ◽

pp. 750

Author(s):

Kiyohiro Ando ◽

Akira Nakagawara

Keyword(s):

Cell Cycle ◽

Dna Damage ◽

Cell Cycle Progression ◽

Parp Inhibitors ◽

Cell Cycle Checkpoint ◽

Mitotic Catastrophe ◽

Malignant Neoplasms ◽

Checkpoint Kinases ◽

Molecular Features ◽

Cycle Checkpoint

Unrestrained proliferation is a common feature of malignant neoplasms. Targeting the cell cycle is a therapeutic strategy to prevent unlimited cell division. Recently developed rationales for these selective inhibitors can be subdivided into two categories with antithetical functionality. One applies a “brake” to the cell cycle to halt cell proliferation, such as with inhibitors of cell cycle kinases. The other “accelerates” the cell cycle to initiate replication/mitotic catastrophe, such as with inhibitors of cell cycle checkpoint kinases. The fate of cell cycle progression or arrest is tightly regulated by the presence of tolerable or excessive DNA damage, respectively. This suggests that there is compatibility between inhibitors of DNA repair kinases, such as PARP inhibitors, and inhibitors of cell cycle checkpoint kinases. In the present review, we explore alterations to the cell cycle that are concomitant with altered DNA damage repair machinery in unfavorable neuroblastomas, with respect to their unique genomic and molecular features. We highlight the vulnerabilities of these alterations that are attributable to the features of each. Based on the assessment, we offer possible therapeutic approaches for personalized medicine, which are seemingly antithetical, but both are promising strategies for targeting the altered cell cycle in unfavorable neuroblastomas.

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PARP Power: A Structural Perspective on PARP1, PARP2, and PARP3 in DNA Damage Repair and Nucleosome Remodelling

International Journal of Molecular Sciences ◽

10.3390/ijms22105112 ◽

2021 ◽

Vol 22 (10) ◽

pp. 5112

Author(s):

Lotte van Beek ◽

Éilís McClay ◽

Saleha Patel ◽

Marianne Schimpl ◽

Laura Spagnolo ◽

...

Keyword(s):

Dna Damage ◽

Dna Binding ◽

Parp Inhibitors ◽

Covalent Modification ◽

Activation Mechanism ◽

Cancer Therapies ◽

Damage Repair ◽

Complementary Role ◽

Functional Understanding

Poly (ADP-ribose) polymerases (PARP) 1-3 are well-known multi-domain enzymes, catalysing the covalent modification of proteins, DNA, and themselves. They attach mono- or poly-ADP-ribose to targets using NAD+ as a substrate. Poly-ADP-ribosylation (PARylation) is central to the important functions of PARP enzymes in the DNA damage response and nucleosome remodelling. Activation of PARP happens through DNA binding via zinc fingers and/or the WGR domain. Modulation of their activity using PARP inhibitors occupying the NAD+ binding site has proven successful in cancer therapies. For decades, studies set out to elucidate their full-length molecular structure and activation mechanism. In the last five years, significant advances have progressed the structural and functional understanding of PARP1-3, such as understanding allosteric activation via inter-domain contacts, how PARP senses damaged DNA in the crowded nucleus, and the complementary role of histone PARylation factor 1 in modulating the active site of PARP. Here, we review these advances together with the versatility of PARP domains involved in DNA binding, the targets and shape of PARylation and the role of PARPs in nucleosome remodelling.

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Differences in PARP Inhibitors for the Treatment of Ovarian Cancer: Mechanisms of Action, Pharmacology, Safety, and Efficacy

International Journal of Molecular Sciences ◽

10.3390/ijms22084203 ◽

2021 ◽

Vol 22 (8) ◽

pp. 4203

Author(s):

Giorgio Valabrega ◽

Giulia Scotto ◽

Valentina Tuninetti ◽

Arianna Pani ◽

Francesco Scaglione

Keyword(s):

Ovarian Cancer ◽

Signal Transduction ◽

Dna Damage ◽

Chemical Structure ◽

Parp Inhibitors ◽

Mechanisms Of Action ◽

Point Of View ◽

Safety And Efficacy ◽

Damage Repair ◽

Pharmacokinetic Properties

Poly(ADP-ribose) polymerases (PARP) are proteins responsible for DNA damage detection and signal transduction. PARP inhibitors (PARPi) are able to interact with the binding site for PARP cofactor (NAD+) and trapping PARP on the DNA. In this way, they inhibit single-strand DNA damage repair. These drugs have been approved in recent years for the treatment of ovarian cancer. Although they share some similarities, from the point of view of the chemical structure and pharmacodynamic, pharmacokinetic properties, these drugs also have some substantial differences. These differences may underlie the different safety profiles and activity of PARPi.

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