Identification and functional analyses of concomitant monoallelic mutations in Fanconi anemia/BRCA pathway genes in the germline of children with cancer

点击翻译按钮获取中文摘要

Lifestyle factors are largely negligible in childhood cancer and therefore, inherited germline mutations in cancer predisposition genes (CPGs) presumably contribute to a yet underestimated extent. Recent studies indicate that a considerable proportion of childhood cancers (8.5%) show mutations in CPGs. However, the exact proportion of children with a malignancy that is attributable to an underlying CPS is still unclear. Additionally, the relative contribution of inherited versus de novo germline mutations in CPGs, and thus the risk of recurrence in other children, still remains unclear. Whole-exome sequencing (WES) of parents-child trios proofed as a promising state-of-the-art strategy to identify causative genetic variants in protein-coding genes in children with rare diseases. To find relevant single nucleotide variants (SNVs) we applied WES on the germline of children with cancer and their parents. Interestingly, our WES analyses identified a genetic phenomenon characterized by the presence of (at least) two independent, monoallelic germline mutations in genes involved in the FA/BRCA pathway in 25% of pediatric cancers including leukemias and solid tumors. The mutations were either inherited by the (so far) clinically healthy parents or one SNV was transmitted from the mother/or father, whereas the second SNV occurred de novo. Such combinations of digenic monoallelic FA/BRCA pathway mutations may substantially compromise DNA repair and lead to genomic instability, which is a hallmark of cancer. From the clinical point of view, such cooperative/synergistic effects leading to deregulation of the FA/BRCA pathway perfectly matches with the clinical phenotype of these children and parents. Thus, our preliminary findings could have important clinical implications for patients and their at-risk family members. In this research proposal we intend to address the following aims: (1) we will systematically analyze children and adolescents with cancer by using parents-child trio WES to identify aberrations/mutations in FA/BRCA pathway genes, (2) we will functionally analyze identified monoallelic FA/BRCA pathway mutations (which likely play a role in DNA damage response and DNA repair) using patient cells and ectopic cell models and (3) we will elucidate the functional interplay of the combined, monoallelic FA/BRCA pathway mutations on the cellular and molecular level using molecular cell biology and biochemistry. Our results are expected to provide fundamental novel insights into the development of inherited childhood cancers and will contribute to identify novel strategies for diagnosis and treatment.