The MRE11, RAD50, and NBN genes encode for the nuclear MRN protein complex, which senses the DNA double strand breaks and initiates the DNA repair. The MRN complex also participates in the activation of ATM kinase, which coordinates DNA repair with the p53-dependent cell cycle checkpoint arrest. Carriers of homozygous germline pathogenic variants in the MRN complex genes or compound heterozygotes develop phenotypically distinct rare autosomal recessive syndromes characterized by chromosomal instability and neurological symptoms. Heterozygous germline alterations in the MRN complex genes have been associated with a poorly-specified predisposition to various cancer types. Somatic alterations in the MRN complex genes may represent valuable predictive and prognostic biomarkers in cancer patients. MRN complex genes have been targeted in several next-generation sequencing panels for cancer and neurological disorders, but interpretation of the identified alterations is challenging due to the complexity of MRN complex function in the DNA damage response. In this review, we outline the structural characteristics of the MRE11, RAD50 and NBN proteins, the assembly and functions of the MRN complex from the perspective of clinical interpretation of germline and somatic alterations in the MRE11, RAD50 and NBN genes.

• Keywords
• ATLD, DNA repair, MRE11, NBN, NBS, NBSLD, NGS, RAD50, TP53, hereditary cancer syndromes, variant interpretation,
• MeSH
• Ataxia Telangiectasia Mutated Proteins genetics   metabolism   MeSH
• DNA-Binding Proteins genetics   metabolism   MeSH
• DNA Repair Enzymes genetics   metabolism   MeSH
• MRE11 Homologue Protein genetics   metabolism   MeSH
• Acid Anhydride Hydrolases genetics   metabolism   MeSH
• Nuclear Proteins genetics   metabolism   MeSH
• Humans MeSH
• Tumor Suppressor Proteins * genetics   MeSH
• DNA Repair genetics   MeSH
• Cell Cycle Proteins * metabolism   MeSH
• Check Tag
• Humans MeSH
• Publication type
• Journal Article MeSH
• Review MeSH
• Names of Substances
• Ataxia Telangiectasia Mutated Proteins MeSH
• DNA-Binding Proteins MeSH
• DNA Repair Enzymes MeSH
• MRE11 Homologue Protein MeSH
• Acid Anhydride Hydrolases MeSH
• Nuclear Proteins MeSH
• Tumor Suppressor Proteins * MeSH
• NBN protein, human MeSH Browser
• Cell Cycle Proteins * MeSH
• RAD50 protein, human MeSH Browser

Germline alterations in many genes coding for proteins regulating DNA repair and DNA damage response (DDR) to DNA double-strand breaks (DDSB) have been recognized as pathogenic factors in hereditary cancer predisposition. The ATM-CHEK2-p53 axis has been documented as a backbone for DDR and hypothesized as a barrier against cancer initiation. However, although CHK2 kinase coded by the CHEK2 gene expedites the DDR signal, its function in activation of p53-dependent cell cycle arrest is dispensable. CHEK2 mutations rank among the most frequent germline alterations revealed by germline genetic testing for various hereditary cancer predispositions, but their interpretation is not trivial. From the perspective of interpretation of germline CHEK2 variants, we review the current knowledge related to the structure of the CHEK2 gene, the function of CHK2 kinase, and the clinical significance of CHEK2 germline mutations in patients with hereditary breast, prostate, kidney, thyroid, and colon cancers.

• Keywords
• CHEK2, CHK2, KAP1, WIP1, breast cancer, checkpoint kinase 2, colorectal cancer, germline mutation, hereditary cancer, prostate cancer, renal cancer, thyroid cancer,
• MeSH
• Checkpoint Kinase 2 chemistry   genetics   metabolism   MeSH
• Genetic Predisposition to Disease * MeSH
• Humans MeSH
• Mutation Rate MeSH
• Neoplasms enzymology   genetics   MeSH
• Substrate Specificity MeSH
• Germ-Line Mutation genetics   MeSH
• Animals MeSH
• Check Tag
• Humans MeSH
• Animals MeSH
• Publication type
• Journal Article MeSH
• Research Support, Non-U.S. Gov't MeSH
• Review MeSH
• Names of Substances
• Checkpoint Kinase 2 MeSH
• CHEK2 protein, human MeSH Browser

Survivin, as an antiapoptotic protein often overexpressed in cancer cells, is a logical target for potential cancer treatment. By overexpressing survivin, cancer cells can avoid apoptotic cell death and often become resistant to treatments, representing a significant obstacle in modern oncology. A survivin suppressor, an imidazolium-based compound known as YM-155, is nowadays studied as an attractive anticancer agent. Although survivin suppression by YM-155 is evident, researchers started to report that YM-155 is also an inducer of DNA damage introducing yet another anticancer mechanism of this drug. Moreover, the concentrations of YM-155 for DNA damage induction seems to be far lower than those needed for survivin inhibition. Understanding the molecular mechanism of action of YM-155 is of vital importance for modern personalized medicine involving the selection of responsive patients and possible treatment combinations. This review focuses mainly on the documented effects of YM-155 on DNA damage signaling pathways. It summarizes up to date literature, and it outlines the molecular mechanism of YM-155 action in the context of the DNA damage field.

• Keywords
• DNA damage, YM-155, molecular mechanism of action, survivin,
• MeSH
• DNA Breaks, Double-Stranded drug effects   MeSH
• Imidazoles pharmacology   MeSH
• Humans MeSH
• Naphthoquinones pharmacology   MeSH
• DNA Damage drug effects   MeSH
• Survivin metabolism   MeSH
• Animals MeSH
• Check Tag
• Humans MeSH
• Animals MeSH
• Publication type
• Journal Article MeSH
• Review MeSH
• Names of Substances
• Imidazoles MeSH
• Naphthoquinones MeSH
• sepantronium MeSH Browser
• Survivin MeSH