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BRCA1/2-mutated cancer cells adapt to the genome instability caused by their deficiency in homologous recombination (HR). Identification of these adaptive mechanisms may provide therapeutic strategies to target tumors caused by the loss of these genes. In the present study, we report genome-scale CRISPR-Cas9 synthetic lethality screens in isogenic pairs of BRCA1- and BRCA2-deficient cells and identify CIP2A as an essential gene in BRCA1- and BRCA2-mutated cells. CIP2A is cytoplasmic in interphase but, in mitosis, accumulates at DNA lesions as part of a complex with TOPBP1, a multifunctional genome stability factor. Unlike PARP inhibition, CIP2A deficiency does not cause accumulation of replication-associated DNA lesions that require HR for their repair. In BRCA-deficient cells, the CIP2A-TOPBP1 complex prevents lethal mis-segregation of acentric chromosomes that arises from impaired DNA synthesis. Finally, physical disruption of the CIP2A-TOPBP1 complex is highly deleterious in BRCA-deficient tumors, indicating that CIP2A represents an attractive synthetic lethal therapeutic target for BRCA1- and BRCA2-mutated cancers.
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http://dx.doi.org/10.1038/s43018-021-00266-w | DOI Listing |
ACS Synth Biol
September 2025
A.N. Bach Institute of Biochemistry, Research Center of Biotechnology of the Russian Academy of Sciences, Moscow 119071, Russian Federation.
African swine fever virus (ASFV) is a large DNA virus that causes a highly lethal disease in pigs and currently has no effective vaccines or antiviral treatments available. We designed a protein switch that combines the DNase domain of colicin E9 (DNase E9) and its inhibitor Im9 with the viral protease cleavage site. The complex is only destroyed in the presence of an ASFV pS273R protease, which releases DNase activity.
View Article and Find Full Text PDFEur J Med Chem
September 2025
State Key Laboratory of Natural Medicines and Department of Medicinal Chemistry, School of Pharmacy, China Pharmaceutical University, Nanjing, 211198, PR China. Electronic address:
The Werner syndrome RecQ helicase (WRN) has recently emerged as a novel synthetic lethality target for microsatellite instability-high (MSI-H) cancers. However, available WRN inhibitors or degraders is still lacking so far. Particularly, chemically designed probes capable of degrading WRN irrespective of microsatellite status remain unexplored.
View Article and Find Full Text PDFJ Med Chem
September 2025
Repare Therapeutics, 7171 Frederick-Banting, Building 2, H4S 1Z9 Montréal, Québec, Canada.
DNA polymerase theta (Polθ) plays a critical role in repairing DNA double-strand breaks through microhomology-mediated end joining (MMEJ) and has emerged as a key synthetic lethal drug target in cancers with homologous recombination (HR) deficiencies. Its inhibition has shown a strong potential to synergize with PARP inhibitors, particularly in tumors with deleterious or mutations. Here, we describe the discovery and preclinical development of RP-2119, a selective, potent, and bioavailable Polθ ATPase inhibitor.
View Article and Find Full Text PDFJ Org Chem
September 2025
Johns Hopkins University, Department of Chemistry, 3400 N. Charles St., Baltimore, Maryland 21218, United States.
Base excision repair (BER) is a DNA repair pathway responsible for protecting the genome against modified nucleotides. DNA polymerase β (Pol β) participates in this process by removing the remnants of a damaged nucleotide and filling in the resulting gap. Pol β is overexpressed in some cancers and is synthetic lethal in cells deficient in BRCA1/2, providing additional impetus for identifying inhibitors of this enzyme.
View Article and Find Full Text PDFCancer Genet
August 2025
National Institute of Immunology, Aruna Asaf Ali Marg, New Delhi, India. Electronic address:
Cancer is a complex and heterogeneous disease characterized by the accumulation of genetic and epigenetic alterations that drive uncontrolled cellular proliferation and survival. This review provides a comprehensive overview of key cancer driver genes, including oncogenes such as KRAS and PIK3CA, as well as tumor suppressor genes like TP53, PTEN, and CDKN2A, highlighting their molecular mechanisms and roles across various types of cancer. Leveraging insights from large-scale cancer genome initiatives and whole-genome sequencing, we examine the landscape of somatic mutations and their association with hallmark cancer pathways, including cell cycle regulation, apoptosis, metabolic reprogramming, and immune evasion.
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