Ribosomal DNA (rDNA) encodes the ribosomal RNA genes and represents an intrinsically unstable genomic region. However, the underlying mechanisms and implications for genome integrity remain elusive. Here, we use Bloom syndrome (BS), a rare genetic disease characterized by DNA repair defects and hyper-unstable rDNA, as a model to investigate the mechanisms leading to rDNA instability. We find that in Bloom helicase (BLM) proficient cells, the homologous recombination (HR) pathway in rDNA resembles that in nuclear chromatin; it is initiated by resection, replication protein A (RPA) loading and BRCA2-dependent RAD51 filament formation. However, BLM deficiency compromises RPA-loading and BRCA1/2 recruitment to rDNA, but not RAD51 accumulation. RAD51 accumulates at rDNA despite depletion of long-range resection nucleases and rDNA damage results in micronuclei when BLM is absent. In summary, our findings indicate that rDNA is permissive to RAD51 accumulation in the absence of BLM, leading to micronucleation and potentially global genomic instability.
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http://dx.doi.org/10.1038/s41467-024-52189-6 | DOI Listing |
Exp Mol Med
January 2025
Cancer Centre, Faculty of Health Sciences, University of Macau, Taipa, Macau SAR, China.
FHIT is a fragile site tumor suppressor that is primarily inactivated upon tobacco smoking. FHIT loss is frequently observed in lung cancer, making it an important biomarker for the development of targeted therapy for lung cancer. Here, we report that inhibitors of glycogen synthase kinase 3 beta (GSK3β) and the homologous recombination DNA repair (HRR) pathway are synthetic lethal with FHIT loss in lung cancer.
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January 2025
Department of Pathology and Biological Responses, Nagoya University Graduate School of Medicine, 65 Tsurumai-cho, Showa-ku, Nagoya, 466-8550, Japan.
Tumor suppressor BRCA2 executes homologous recombination to repair DNA double-strand breaks in collaboration with RAD51, involving exon 11 and 27. Exon 11 constitutes a region where pathogenic variants (PVs) accumulate, and mutations in this region are known to contribute to carcinogenesis. However, the impact of the heterozygous PVs of BRCA2 exon 11 on the life quality beyond cancer risk, including male fertility, remains unclear.
View Article and Find Full Text PDFClin Transl Radiat Oncol
March 2025
Department of Molecular Genetics, Oncode Institute, Erasmus MC Cancer Institute, Erasmus University Medical Center, Rotterdam, Netherlands (the).
Background And Purpose: Radiotherapy induces tumor cell killing by generating DNA double strand breaks (DSBs). The effectiveness of radiotherapy is significantly influenced by the repair of DSBs, which counteracts this lethal effect. Current investigations are focused on determining whether non-homologous end joining (NHEJ) or homologous recombination is the predominant repair pathway following proton and photon radiation.
View Article and Find Full Text PDFTransl Oncol
January 2025
Department of Basic Medical Sciences, Zhejiang University School of Medicine, Hangzhou, Zhejiang 0310058, China; University of Chinese Academy of Sciences, No. 19A Yuquan Road, Beijing 100049, China; Shandong Laboratory of Yantai Drug Discovery, Bohai Rim Advanced Research Institute for Drug Discovery, Yantai, Shandong 264117, China. Electronic address:
CDK4/6 inhibitors have shown clinical benefits in hormone receptor positive breast cancer. However, monotonous indications and unclear resistance mechanisms greatly limit the clinical application of these inhibitors. We attempt to improve the therapeutic effect of CDK4/6 inhibitors against breast cancer by combination with BET inhibitors.
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October 2024
China National Center for Bioinformation, Beijing 100101, China.
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