Formation of cancerous translocations requires the illegitimate joining of chromosomes containing double-strand breaks (DSBs). It is unknown how broken chromosome ends find their translocation partners within the cell nucleus. Here, we have visualized and quantitatively analysed the dynamics of single DSBs in living mammalian cells. We demonstrate that broken ends are positionally stable and unable to roam the cell nucleus. Immobilization of broken chromosome ends requires the DNA-end binding protein Ku80, but is independent of DNA repair factors, H2AX, the MRN complex and the cohesion complex. DSBs preferentially undergo translocations with neighbouring chromosomes and loss of local positional constraint correlates with elevated genomic instability. These results support a contact-first model in which chromosome translocations predominantly form among spatially proximal DSBs.
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http://dx.doi.org/10.1038/ncb1591 | DOI Listing |
Oncol Lett
March 2025
Program in Translational Medicine, Chakri Naruebodindra Medical Institute, Faculty of Medicine Ramathibodi Hospital, Mahidol University, Samutprakarn 10540, Thailand.
Cholangiocarcinoma (CCA) is a biliary tract carcinoma that is challenging to treat due to its heterogeneity and limited treatment options. Genetic alterations in DNA damage response (DDR) pathways and homologous recombination (HR) defects are common in CCA. This has prompted interest in the use of ataxia telangiectasia and Rad3-related protein (ATR) and poly(ADP-ribose) polymerase (PARP) inhibitors to treat CCA.
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January 2025
Radiation Biophysics and Radiobiology Laboratory, Physics Department, University of Pavia, Pavia, Italy.
We present new developments for an ab-initio model of the neutron relative biological effectiveness (RBE) in inducing specific classes of DNA damage. RBE is evaluated as a function of the incident neutron energy and of the depth inside a human-sized reference spherical phantom. The adopted mechanistic approach traces neutron RBE back to its origin, i.
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January 2025
European Molecular Biology Laboratory, European Bioinformatics Institute, Hinxton CB10 1SA, UK. Electronic address:
Osteosarcoma is the most common primary cancer of the bone, with a peak incidence in children and young adults. Using multi-region whole-genome sequencing, we find that chromothripsis is an ongoing mutational process, occurring subclonally in 74% of osteosarcomas. Chromothripsis generates highly unstable derivative chromosomes, the ongoing evolution of which drives the acquisition of oncogenic mutations, clonal diversification, and intra-tumor heterogeneity across diverse sarcomas and carcinomas.
View Article and Find Full Text PDFToxicol Appl Pharmacol
January 2025
Drug Safety Research & Development, Pfizer, Inc., Groton, CT 06340, USA.
One of the potential risk factors of recombinant adeno-associated virus (rAAV)-based gene therapy is insertional mutagenesis, which has been associated with the development of hepatocellular carcinoma (HCC) in rAAV-treated neonatal mice. The objective of this study was to investigate if well-established in vitro cell transformation assays (CTA) in mouse cell lines can detect AAV2 or AAVdj-mediated cell transformation. Since AAV integration at the Rian locus in neonatal mice has been implicated in AAV-mediated HCC, an rAAV vector specifically targeting the mouse Rian locus and an additional rAAV vector previously shown to cause HCC in neonatal mice were both tested for the induction of cell transformation in NIH3T3 cells.
View Article and Find Full Text PDFNat Cell Biol
January 2025
Genome Integrity Unit, Children's Medical Research Institute, University of Sydney, Westmead, New South Wales, Australia.
Double-strand breaks (DSBs) can initiate mitotic catastrophe, a complex oncosuppressive phenomenon characterized by cell death during or after cell division. Here we unveil how cell cycle-regulated DSB repair guides disparate cell death outcomes through single-cell analysis of extended live imaging. Following DSB induction in S or G2, passage of unresolved homologous recombination intermediates into mitosis promotes non-immunogenic intrinsic apoptosis in the immediate attempt at cell division.
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