| 1. |
- Bonagas, Nadilly, et al.
(författare)
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Pharmacological targeting of MTHFD2 suppresses acute myeloid leukemia by inducing thymidine depletion and replication stress
- 2022
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Ingår i: NATURE CANCER. - : Springer Science and Business Media LLC. - 2662-1347. ; 3:2, s. 156-
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Tidskriftsartikel (refereegranskat)abstract
- The folate metabolism enzyme MTHFD2 (methylenetetrahydrofolate dehydrogenase/cyclohydrolase) is consistently overexpressed in cancer but its roles are not fully characterized, and current candidate inhibitors have limited potency for clinical development. In the present study, we demonstrate a role for MTHFD2 in DNA replication and genomic stability in cancer cells, and perform a drug screen to identify potent and selective nanomolar MTHFD2 inhibitors; protein cocrystal structures demonstrated binding to the active site of MTHFD2 and target engagement. MTHFD2 inhibitors reduced replication fork speed and induced replication stress followed by S-phase arrest and apoptosis of acute myeloid leukemia cells in vitro and in vivo, with a therapeutic window spanning four orders of magnitude compared with nontumorigenic cells. Mechanistically, MTHFD2 inhibitors prevented thymidine production leading to misincorporation of uracil into DNA and replication stress. Overall, these results demonstrate a functional link between MTHFD2-dependent cancer metabolism and replication stress that can be exploited therapeutically with this new class of inhibitors. Helleday and colleagues describe a nanomolar MTHFD2 inhibitor that causes replication stress and DNA damage accumulation in cancer cells via thymidine depletion, demonstrating a potential therapeutic strategy in AML tumors in vivo.
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| 2. |
- De Maria, Giovanni Luigi, et al.
(författare)
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Novel Indices of Coronary Physiology : Do We Need Alternatives to Fractional Flow Reserve?
- 2020
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Ingår i: Circulation. Cardiovascular Interventions. - 1941-7640 .- 1941-7632. ; 13:4
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Forskningsöversikt (refereegranskat)abstract
- Fractional flow reserve is the current invasive gold standard for assessing the ischemic potential of an angiographically intermediate coronary stenosis. Procedural cost and time, the need for coronary vessel instrumentation, and the need to administer adenosine to achieve maximal hyperemia remain integral components of invasive fractional flow reserve. The number of new alternatives to fractional flow reserve has proliferated over the last ten years using techniques ranging from alternative pressure wire metrics to anatomic simulation via angiography or intravascular imaging. This review article provides a critical description of the currently available or under-development alternatives to fractional flow reserve with a special focus on the available evidence, pros, and cons for each with a view towards their clinical application in the near future for the functional assessment of coronary artery disease.
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| 3. |
- Jemth, Ann-Sofie, et al.
(författare)
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MutT homologue 1 (MTH1) catalyzes the hydrolysis of mutagenic O6-methyl-dGTP
- 2018
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Ingår i: Nucleic Acids Research. - : Oxford University Press (OUP). - 0305-1048 .- 1362-4962. ; 46:20, s. 10888-10904
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Tidskriftsartikel (refereegranskat)abstract
- Nucleotides in the free pool are more susceptible to nonenzymatic methylation than those protected in the DNA double helix. Methylated nucleotides like O6-methyl-dGTP can be mutagenic and toxic if incorporated into DNA. Removal of methylated nucleotides from the nucleotide pool may therefore be important to maintain genome integrity. We show that MutT homologue 1 (MTH1) efficiently catalyzes the hydrolysis of O6-methyl-dGTP with a catalytic efficiency similar to that for 8-oxo-dGTP. O6-methyl-dGTP activity is exclusive to MTH1 among human NUDIX proteins and conserved through evolution but not found in bacterial MutT. We present a high resolution crystal structure of human and zebrafish MTH1 in complex with O6-methyl-dGMP. By microinjecting fertilized zebrafish eggs with O6-methyl-dGTP and inhibiting MTH1 we demonstrate that survival is dependent on active MTH1 in vivo. O6-methyl-dG levels are higher in DNA extracted from zebrafish embryos microinjected with O6-methyl-dGTP and inhibition of O6-methylguanine-DNA methyl transferase (MGMT) increases the toxicity of O6-methyl-dGTP demonstrating that O6-methyl-dGTP is incorporated into DNA. MTH1 deficiency sensitizes human cells to the alkylating agent Temozolomide, a sensitization that is more pronounced upon MGMT inhibition. These results expand the cellular MTH1 function and suggests MTH1 also is important for removal of methylated nucleotides from the nucleotide pool.
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| 4. |
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| 5. |
- Scaletti, Emma Rose, et al.
(författare)
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MutT homologue 1 (MTH1) removes N6-methyl-dATP from the dNTP pool
- 2020
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Ingår i: Journal of Biological Chemistry. - 0021-9258 .- 1083-351X. ; 295:15, s. 4761-4772
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Tidskriftsartikel (refereegranskat)abstract
- MutT homologue 1 (MTH1) removes oxidized nucleotides from the nucleotide pool and thereby prevents their incorporation into the genome and thereby reduces genotoxicity. We previously reported that MTH1 is an efficient catalyst of O6-methyl-dGTP hydrolysis suggesting that MTH1 may also sanitize the nucleotide pool from other methylated nucleotides. We here show that MTH1 efficiently catalyzes the hydrolysis of N6-methyl-dATP to N6-methyl-dAMP and further report that N6-methylation of dATP drastically increases the MTH1 activity. We also observed MTH1 activity with N6-methyl-ATP, albeit at a lower level. We show that N6-methyl-dATP is incorporated into DNA in vivo, as indicated by increased N6-methyl-dA DNA levels in embryos developed from MTH1 knock-out zebrafish eggs microinjected with N6-methyl-dATP compared with noninjected embryos. N6-methyl-dATP activity is present in MTH1 homologues from distantly related vertebrates, suggesting evolutionary conservation and indicating that this activity is important. Of note, N6-methyl-dATP activity is unique to MTH1 among related NUDIX hydrolases. Moreover, we present the structure of N6-methyl-dAMP?bound human MTH1, revealing that the N6-methyl group is accommodated within a hydrophobic active-site subpocket explaining why N6-methyl-dATP is a good MTH1 substrate. N6-methylation of DNA and RNA has been reported to have epigenetic roles and to affect mRNA metabolism. We propose that MTH1 acts in concert with adenosine deaminase-like protein isoform 1 (ADAL1) to prevent incorporation of N6-methyl-(d)ATP into DNA and RNA. This would hinder potential dysregulation of epigenetic control and RNA metabolism via conversion of N6-methyl-(d)ATP to N6-methyl-(d)AMP, followed by ADAL1-catalyzed deamination producing (d)IMP that can enter the nucleotide salvage pathway.
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| 6. |
- Visnes, Torkild, et al.
(författare)
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Small-molecule inhibitor of OGG1 suppresses proinflammatory gene expression and inflammation
- 2018
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Ingår i: Science. - : American Association for the Advancement of Science (AAAS). - 0036-8075 .- 1095-9203. ; 362:6416, s. 834-
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Tidskriftsartikel (refereegranskat)abstract
- The onset of inflammation is associated with reactive oxygen species and oxidative damage to macromolecules like 7,8-dihydro-8-oxoguanine (8-oxoG) in DNA. Because 8-oxoguanine DNA glycosylase 1 (OGG1) binds 8-oxoG and because Ogg1-deficient mice are resistant to acute and systemic inflammation, we hypothesized that OGG1 inhibition may represent a strategy for the prevention and treatment of inflammation. We developed TH5487, a selective active-site inhibitor of OGG1, which hampers OGG1 binding to and repair of 8-oxoG and which is well tolerated by mice. TH5487 prevents tumor necrosis factor-alpha-induced OGG1-DNA interactions at guanine-rich promoters of proinflammatory genes. This, in turn, decreases DNA occupancy of nuclear factor kappa B and proinflammatory gene expression, resulting in decreased immune cell recruitment to mouse lungs. Thus, we present a proof of concept that targeting oxidative DNA repair can alleviate inflammatory conditions in vivo.
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| 7. |
- Visnes, Torkild, et al.
(författare)
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Targeting OGG1 arrests cancer cell proliferation by inducing replication stress
- 2020
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Ingår i: Nucleic Acids Research. - : Oxford University Press (OUP). - 0305-1048 .- 1362-4962. ; 48:21, s. 12234-12251
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Tidskriftsartikel (refereegranskat)abstract
- Altered oncogene expression in cancer cells causes loss of redox homeostasis resulting in oxidative DNA damage, e.g. 8-oxoguanine (8-oxoG), repaired by base excision repair (BER). PARP1 coordinates BER and relies on the upstream 8-oxoguanine-DNA glycosylase (OGG1) to recognise and excise 8-oxoG. Here we hypothesize that OGG1 may represent an attractive target to exploit reactive oxygen species (ROS) elevation in cancer. Although OGG1 depletion is well tolerated in non-transformed cells, we report here that OGG1 depletion obstructs A3 T-cell lymphoblastic acute leukemia growth in vitro and in vivo, validating OGG1 as a potential anti-cancer target. In line with this hypothesis, we show that OGG1 inhibitors (OGG1i) target a wide range of cancer cells, with a favourable therapeutic index compared to non-transformed cells. Mechanistically, OGG1i and shRNA depletion cause S-phase DNA damage, replication stress and proliferation arrest or cell death, representing a novel mechanistic approach to target cancer. This study adds OGG1 to the list of BER factors, e.g. PARP1, as potential targets for cancer treatment.
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| 8. |
- Wallenius, Anders, et al.
(författare)
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Expression and recruitment of uracil-DNA glycosylase are regulated by E2A during antibody diversification
- 2014
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Ingår i: Molecular Immunology. - : Elsevier BV. - 0161-5890 .- 1872-9142. ; 60:1, s. 23-31
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Tidskriftsartikel (refereegranskat)abstract
- B-lymphocytes can modify their immunoglobulin (Ig) genes to generate specific antibodies with a new isotype and enhanced affinity against an antigen. Activation-induced cytidine deaminase (AID), which is positively regulated by the transcription factor E2A, is the key enzyme that initiates these processes by deaminating cytosine to uracil in Ig genes. Nuclear uracil-DNA glycosylase (UNG2) is subsequently required for uracil processing in the generation of high affinity antibodies of different isotypes. Here we show that the transcription factor E2A binds to the UNG2 promoter and represses UNG2 expression. Inhibition of E2A by binding of Ca2+-activated calmodulin alleviates this repression. Furthermore, we demonstrate that UNG2 preferentially accumulates in regions of the Ig heavy chain (IgH) gene containing AID hotspots. Calmodulin inhibition of E2A strongly enhances this UNG2 accumulation, indicating that it is negatively regulated by E2A as well. We show also that over-expression of E2A can suppress class switch recombination. The results suggest that E2A is a key factor in regulating the balance between AID and UNG2, both at expression and Ig targeting levels, to stimulate Ig diversification and suppress normal DNA repair processes. (c) 2014 Elsevier Ltd. All rights reserved.
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| 9. |
- Zhang, Si Min, et al.
(författare)
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Development of a chemical probe against NUDT15
- 2020
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Ingår i: Nature Chemical Biology. - : Springer Science and Business Media LLC. - 1552-4450 .- 1552-4469. ; 16:10, s. 1120-1128
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Tidskriftsartikel (refereegranskat)abstract
- The NUDIX hydrolase NUDT15 was originally implicated in sanitizing oxidized nucleotides, but was later shown to hydrolyze the active thiopurine metabolites, 6-thio-(d)GTP, thereby dictating the clinical response of this standard-of-care treatment for leukemia and inflammatory diseases. Nonetheless, its physiological roles remain elusive. Here, we sought to develop small-molecule NUDT15 inhibitors to elucidate its biological functions and potentially to improve NUDT15-dependent chemotherapeutics. Lead compound TH1760 demonstrated low-nanomolar biochemical potency through direct and specific binding into the NUDT15 catalytic pocket and engaged cellular NUDT15 in the low-micromolar range. We also employed thiopurine potentiation as a proxy functional readout and demonstrated that TH1760 sensitized cells to 6-thioguanine through enhanced accumulation of 6-thio-(d)GTP in nucleic acids. A biochemically validated, inactive structural analog, TH7285, confirmed that increased thiopurine toxicity takes place via direct NUDT15 inhibition. In conclusion, TH1760 represents the first chemical probe for interrogating NUDT15 biology and potential therapeutic avenues.
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