Jelinic Petar, Eccles Laura A, Tseng Jill, Cybulska Paulina, Wielgos Monicka, Powell Simon N, Levine Douglas A
Laura and Isaac Perlmutter Cancer Center, Division of Gynecologic Oncology, Department of OB/GYN, NYU Langone Medical Center, New York, USA.
Departments of Radiation Oncology and Molecular Biology, Memorial Sloan Kettering Cancer Center, New York, USA.
Oncotarget. 2017 Feb 21;8(8):13792-13804. doi: 10.18632/oncotarget.14637.
BRCA1 and BRCA2 are essential for the repair of double-strand DNA breaks, and alterations in these genes are a hallmark of breast and ovarian carcinomas. Other functionally related genes may also play important roles in carcinogenesis. Amplification of EMSY, a putative BRCAness gene, has been suggested to impair DNA damage repair by suppressing BRCA2 function. We employed direct repeat GFP (DR-GFP) and RAD51 foci formation assays to show that EMSY overexpression impairs the repair of damaged DNA, suggesting that EMSY belongs to the family of BRCAness proteins. We also identified a novel phospho-site at threonine 207 (T207) and demonstrated its role in EMSY-driven suppression of DNA damage repair. In vitro kinase assays established that protein kinase A (PKA) directly phosphorylates the T207 phospho-site. Immunoprecipitation experiments suggest that EMSY-driven suppression of DNA damage repair is a BRCA2-independent process. The data also suggest that EMSY amplification is a BRCAness feature, and may help to expand the population of patients who could benefit from targeted therapies that are also effective in BRCA1/2-mutant cancers.
BRCA1和BRCA2对于双链DNA断裂的修复至关重要，这些基因的改变是乳腺癌和卵巢癌的一个标志。其他功能相关基因在致癌过程中也可能起重要作用。EMSY是一种假定的类BRCA基因，其扩增被认为通过抑制BRCA2功能来损害DNA损伤修复。我们采用直接重复绿色荧光蛋白（DR-GFP）和RAD51灶形成试验，以表明EMSY过表达会损害受损DNA的修复，这表明EMSY属于类BRCA蛋白家族。我们还在苏氨酸207（T207）处鉴定出一个新的磷酸化位点，并证明了其在EMSY驱动的DNA损伤修复抑制中的作用。体外激酶试验证实蛋白激酶A（PKA）直接使T207磷酸化位点磷酸化。免疫沉淀实验表明，EMSY驱动的DNA损伤修复抑制是一个不依赖BRCA2的过程。数据还表明，EMSY扩增是一种类BRCA特征，可能有助于扩大受益于对BRCA1/2突变癌症也有效的靶向治疗的患者群体。
