Transcription-associated topoisomerase 2α activity is a major effector of cytotoxicity induced by G-quadruplex ligands
- Institut de Pharmacologie et Biologie Structurale, IPBS, Université de Toulouse, CNRS, UPS, Toulouse, France, France
- Muséum National d'Histoire Naturelle, CNRS, INSERM, France
- INRAE, UR 875, Genotoul Bioinfo, Castanet-Tolosan, France, France
- INRAE, US 1426, Castanet-Tolosan, France, France
- UMR CNRS 5250, Université Grenoble Alpes, Grenoble 38058, France, France
Abstract
G-quadruplexes (G4) are non-canonical DNA structures found in the genome of most species including human. Small molecules stabilizing these structures, called G4 ligands, have been identified and, for some of them, shown to induce cytotoxic DNA double-strand breaks. Through the use of an unbiased genetic approach, we identify here topoisomerase 2-alpha (TOP2A) as a major effector of cytotoxicity induced by two clastogenic G4 ligands, pyridostatin and CX-5461, the latter molecule currently undergoing phase I/II clinical trials in oncology. We show that both TOP2 activity and transcription account for DNA break production following G4 ligand treatments. In contrast, clastogenic activity of these G4 ligands is countered by topoisomerase 1 (TOP1), which limits co-transcriptional G4 formation, and by factors promoting transcriptional elongation. Altogether our results support that clastogenic G4 ligands act as DNA structure-driven TOP2-poisons at transcribed regions bearing G4 structures.
Data availability
RNA-seq data from wild-type HAP1 and CXR clones have been deposited on SRA with the project ID PRJNA637883
Article and author information
Author details
Jean-Francois Riou
Funding
Agence Nationale de la Recherche (ANR-17-CE18-0002-01)
- Madeleine Bossaert
- Angélique Pipier
- Linh-Trang Nguyễn
- Patrick Calsou
- Sébastien Britton
- Dennis Gomez
Agence Nationale de la Recherche (ANR-16-CE11-0006-01)
- Angélique Pipier
- Jean-Francois Riou
- Eric Defrancq
- Patrick Calsou
- Sébastien Britton
- Dennis Gomez
CANCEROPOLE GSO (Emergence funding CX-Break"")
- Madeleine Bossaert
- Angélique Pipier
- Linh-Trang Nguyễn
- Patrick Calsou
- Sébastien Britton
- Dennis Gomez
Ligue Contre le Cancer (Equipe Labellisée 2018)
- Madeleine Bossaert
- Angélique Pipier
- Linh-Trang Nguyễn
- Patrick Calsou
- Sébastien Britton
- Dennis Gomez
Agence Nationale de la Recherche (ANR-10-INBS-09)
- Céline Noirot
- Remy-Felix Serre
- Olivier Bouchez
The funders had no role in study design, data collection and interpretation, or the decision to submit the work for publication.
Copyright
© 2021, Bossaert et al.
This article is distributed under the terms of the Creative Commons Attribution License permitting unrestricted use and redistribution provided that the original author and source are credited.
Metrics
-
- 4,753
- views
-
- 641
- downloads
-
- 60
- citations
Views, downloads and citations are aggregated across all versions of this paper published by eLife.
Download links
Further reading
-
- Cancer Biology
Why does a normal cell possibly harboring genetic mutations in oncogene or tumor suppressor genes becomes malignant and develops a tumor is a subject of intense debate. Various theories have been proposed but their experimental test has been hampered by the unpredictable and improbable malignant transformation of single cells. Here, using an optogenetic approach we permanently turn on an oncogene (KRASG12V) in a single cell of a zebrafish brain that, only in synergy with the transient co-activation of a reprogramming factor (VENTX/NANOG/OCT4), undergoes a deterministic malignant transition and robustly and reproducibly develops within 6 days into a full-blown tumor. The controlled way in which a single cell can thus be manipulated to give rise to cancer lends support to the ‘ground state theory of cancer initiation’ through ‘short-range dispersal’ of the first malignant cells preceding tumor growth.
-
- Cancer Biology
Most human pancreatic ductal adenocarcinoma (PDAC) are not infiltrated with cytotoxic T cells and are highly resistant to immunotherapy. Over 90% of PDAC have oncogenic KRAS mutations, and phosphoinositide 3-kinases (PI3Ks) are direct effectors of KRAS. Our previous study demonstrated that ablation of Pik3ca in KPC (KrasG12D; Trp53R172H; Pdx1-Cre) pancreatic cancer cells induced host T cells to infiltrate and completely eliminate the tumors in a syngeneic orthotopic implantation mouse model. Now, we show that implantation of Pik3ca−/− KPC (named αKO) cancer cells induces clonal enrichment of cytotoxic T cells infiltrating the pancreatic tumors. To identify potential molecules that can regulate the activity of these anti-tumor T cells, we conducted an in vivo genome-wide gene-deletion screen using αKO cells implanted in the mouse pancreas. The result shows that deletion of propionyl-CoA carboxylase subunit B gene (Pccb) in αKO cells (named p-αKO) leads to immune evasion, tumor progression, and death of host mice. Surprisingly, p-αKO tumors are still infiltrated with clonally enriched CD8+ T cells but they are inactive against tumor cells. However, blockade of PD-L1/PD1 interaction reactivated these clonally enriched T cells infiltrating p-αKO tumors, leading to slower tumor progression and improve survival of host mice. These results indicate that Pccb can modulate the activity of cytotoxic T cells infiltrating some pancreatic cancers and this understanding may lead to improvement in immunotherapy for this difficult-to-treat cancer.
