Service de Génétique, Département de Biologie des Tumeurs, Institut Curie, Paris, France.
Institut de Biologie Intégrative de la Cellule, CEA, CNRS, Université Paris Sud, UMR 9198, Université Paris-Saclay, Gif-sur-Yvette, France.
Mol Cancer Res. 2019 Jan;17(1):54-69. doi: 10.1158/1541-7786.MCR-17-0357. Epub 2018 Sep 26.
mutations have been identified that increase the risk of developing hereditary breast and ovarian cancers. Genetic screening is now offered to patients with a family history of cancer, to adapt their treatment and the management of their relatives. However, a large number of variants of uncertain significance (VUS) are detected. To better understand the significance of these variants, a high-throughput structural and functional analysis was performed on a large set of VUS. Information on both cellular localization and homology-directed DNA repair (HR) capacity was obtained for 78 BRCT missense variants in the UMD-BRCA1 database and measurement of the structural stability and phosphopeptide-binding capacities was performed for 42 mutated BRCT domains. This extensive and systematic analysis revealed that most characterized causal variants affect BRCT-domain solubility in bacteria and all impair BRCA1 HR activity in cells. Furthermore, binding to a set of 5 different phosphopeptides was tested: all causal variants showed phosphopeptide-binding defects and no neutral variant showed such defects. A classification is presented on the basis of mutated BRCT domain solubility, phosphopeptide-binding properties, and VUS HR capacity. These data suggest that HR-defective variants, which present, in addition, BRCT domains either insoluble in bacteria or defective for phosphopeptide binding, lead to an increased cancer risk. Furthermore, the data suggest that variants with a WT HR activity and whose BRCT domains bind with a WT affinity to the 5 phosphopeptides are neutral. The case of variants with WT HR activity and defective phosphopeptide binding should be further characterized, as this last functional defect might be sufficient to lead to tumorigenesis. IMPLICATIONS: The analysis of the current study on BRCA1 structural and functional defects on cancer risk and classification presented may improve clinical interpretation and therapeutic selection.
已经鉴定出一些突变会增加遗传性乳腺癌和卵巢癌的风险。现在为有癌症家族史的患者提供基因筛查，以调整他们的治疗方法和亲属的管理。然而，检测到大量意义不明的变异体 (VUS)。为了更好地理解这些变体的意义，对大量 VUS 进行了高通量结构和功能分析。UMD-BRCA1 数据库中获得了 78 个 BRCT 错义变体的细胞定位和同源定向 DNA 修复 (HR) 能力信息，并对 42 个突变 BRCT 结构域进行了结构稳定性和磷酸肽结合能力的测量。这项广泛而系统的分析表明，大多数特征明确的因果变体影响 BRCT 结构域在细菌中的可溶性，并且所有变体都损害了 BRCA1 在细胞中的 HR 活性。此外，还测试了与一组 5 种不同磷酸肽的结合：所有因果变体均显示出磷酸肽结合缺陷，而无中性变体显示出这种缺陷。根据突变 BRCT 结构域的可溶性、磷酸肽结合特性和 VUS HR 能力提出了一种分类。这些数据表明，HR 缺陷变体，此外，BRCT 结构域在细菌中不可溶或对磷酸肽结合有缺陷，会增加癌症风险。此外，数据表明，具有 WT HR 活性且其 BRCT 结构域与 5 种磷酸肽以 WT 亲和力结合的变体是中性的。对于具有 WT HR 活性且磷酸肽结合有缺陷的变体，应该进一步进行表征，因为最后一个功能缺陷可能足以导致肿瘤发生。意义：对当前关于 BRCA1 结构和功能缺陷与癌症风险和分类的分析可能会改善临床解释和治疗选择。
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