TY - JOUR A1 - Henriksson, Sofia A1 - Calderón-Montaño, José Manuel A1 - Solvie, Daniel A1 - Warpman Berglund, Ulrika A1 - Helleday, Thomas T1 - Overexpressed c-Myc sensitizes cells to TH1579, a mitotic arrest and oxidative DNA damage inducer JF - Biomolecules N2 - Previously, we reported that MTH1 inhibitors TH588 and TH1579 selectively induce oxidative damage and kill Ras-expressing or -transforming cancer cells, as compared to non-transforming immortalized or primary cells. While this explains the impressive anti-cancer properties of the compounds, the molecular mechanism remains elusive. Several oncogenes induce replication stress, resulting in under replicated DNA and replication continuing into mitosis, where TH588 and TH1579 treatment causes toxicity and incorporation of oxidative damage. Hence, we hypothesized that oncogene-induced replication stress explains the cancer selectivity. To test this, we overexpressed c-Myc in human epithelial kidney cells (HA1EB), resulting in increased proliferation, polyploidy and replication stress. TH588 and TH1579 selectively kill c-Myc overexpressing clones, enforcing the cancer cell selective killing of these compounds. Moreover, the toxicity of TH588 and TH1579 in c-Myc overexpressing cells is rescued by transcription, proteasome or CDK1 inhibitors, but not by nucleoside supplementation. We conclude that the molecular toxicological mechanisms of how TH588 and TH1579 kill c-Myc overexpressing cells have several components and involve MTH1-independent proteasomal degradation of c-Myc itself, c-Myc-driven transcription and CDK activation. KW - MTH1 KW - TH588 KW - TH1579 KW - c-Myc KW - replication stress KW - DNA damage KW - cell death KW - cancer Y1 - 2022 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-297547 SN - 2218-273X VL - 12 IS - 12 ER - TY - JOUR A1 - Fischer, Thomas A1 - Hartmann, Oliver A1 - Reissland, Michaela A1 - Prieto-Garcia, Cristian A1 - Klann, Kevin A1 - Pahor, Nikolett A1 - Schülein-Völk, Christina A1 - Baluapuri, Apoorva A1 - Polat, Bülent A1 - Abazari, Arya A1 - Gerhard-Hartmann, Elena A1 - Kopp, Hans-Georg A1 - Essmann, Frank A1 - Rosenfeldt, Mathias A1 - Münch, Christian A1 - Flentje, Michael A1 - Diefenbacher, Markus E. T1 - PTEN mutant non-small cell lung cancer require ATM to suppress pro-apoptotic signalling and evade radiotherapy JF - Cell & Bioscience N2 - Background Despite advances in treatment of patients with non-small cell lung cancer, carriers of certain genetic alterations are prone to failure. One such factor frequently mutated, is the tumor suppressor PTEN. These tumors are supposed to be more resistant to radiation, chemo- and immunotherapy. Results We demonstrate that loss of PTEN led to altered expression of transcriptional programs which directly regulate therapy resistance, resulting in establishment of radiation resistance. While PTEN-deficient tumor cells were not dependent on DNA-PK for IR resistance nor activated ATR during IR, they showed a significant dependence for the DNA damage kinase ATM. Pharmacologic inhibition of ATM, via KU-60019 and AZD1390 at non-toxic doses, restored and even synergized with IR in PTEN-deficient human and murine NSCLC cells as well in a multicellular organotypic ex vivo tumor model. Conclusion PTEN tumors are addicted to ATM to detect and repair radiation induced DNA damage. This creates an exploitable bottleneck. At least in cellulo and ex vivo we show that low concentration of ATM inhibitor is able to synergise with IR to treat PTEN-deficient tumors in genetically well-defined IR resistant lung cancer models. KW - PTEN KW - ATM KW - IR KW - NSCLC KW - radiotherapy KW - cancer KW - DNA-PK KW - PI3K Y1 - 2022 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-299865 SN - 2045-3701 VL - 12 ER - TY - JOUR A1 - Mamontova, Victoria A1 - Trifault, Barbara A1 - Burger, Kaspar T1 - Compartment-specific proximity ligation expands the toolbox to assess the interactome of the long non-coding RNA NEAT1 JF - International Journal of Molecular Sciences N2 - The nuclear paraspeckle assembly transcript 1 (NEAT1) locus encodes two long non-coding (lnc)RNA isoforms that are upregulated in many tumours and dynamically expressed in response to stress. NEAT1 transcripts form ribonucleoprotein complexes with numerous RNA-binding proteins (RBPs) to assemble paraspeckles and modulate the localisation and activity of gene regulatory enzymes as well as a subset of messenger (m)RNA transcripts. The investigation of the dynamic composition of NEAT1-associated proteins and mRNAs is critical to understand the function of NEAT1. Interestingly, a growing number of biochemical and genetic tools to assess NEAT1 interactomes has been reported. Here, we discuss the Hybridisation Proximity (HyPro) labeling technique in the context of NEAT1. HyPro labeling is a recently developed method to detect spatially ordered interactions of RNA-containing nuclear compartments in cultured human cells. After introducing NEAT1 and paraspeckles, we describe the advantages of the HyPro technology in the context of other methods to study RNA interactomes, and review the key findings in mapping NEAT1-associated RNA transcripts and protein binding partners. We further discuss the limitations and potential improvements of HyPro labeling, and conclude by delineating its applicability in paraspeckles-related cancer research. KW - proximity ligation KW - paraspeckles KW - NEAT1 KW - long non-coding RNA KW - cancer Y1 - 2022 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-284185 SN - 1422-0067 VL - 23 IS - 8 ER -