Genetic Screens Reveal FEN1 and APEX2 as BRCA2 Synthetic Lethal Targets
Genetic Screens Reveal FEN1 and APEX2 as BRCA2 Synthetic Lethal Targets
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DOI：
10.1016/j.molcel.2018.12.008
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发表时间：
2019-03-07
期刊：
影响因子：
16
通讯作者：
Elledge, Stephen J.
中科院分区：
文献类型：
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作者：
Mengwasser, Kristen E.;Adeyemi, Richard O.;Elledge, Stephen J.
BRCA 1或BRCA 2失活会导致乳腺癌和卵巢癌，但也会导致对聚（ADP-核糖）聚合酶（PARP）抑制剂的脆弱性。为了寻找在BRCA 2缺陷背景中抑制是合成致死的其他靶点，我们筛选了两对具有DNA修复聚焦的小发夹RNA（shRNA）和CRISPR（成簇规则间隔短回文重复序列）库的BRCA 2等基因细胞系。我们发现BRCA 2缺陷细胞选择性地依赖于多种途径，包括碱基切除修复、ATR信号传导和剪接。我们鉴定了APEX 2和FEN 1是合成的致死基因，BRCA 1和BRCA 2都丧失了功能。BRCA 2缺陷细胞需要Ape 2（APEX 2）的脱嘌呤核酸内切酶活性和PCNA结合结构域，但不需要Ape 1（APEX 1）。此外，BRCA 2缺陷型细胞需要Fen 1的5'侧翼核酸内切酶，但不需要Fen 1的5'-3 '外切核酸酶活性，化学抑制Fen 1选择性靶向BRCA缺陷型细胞。最后，我们开发了一种微同源介导的末端连接（MMEJ）报告，并表明Fen 1参与MMEJ，强调了MMEJ作为同源重组（HR）缺陷背景下的侧枝修复途径的重要性。
BRCA1 or BRCA2 inactivation drives breast and ovarian cancer but also creates vulnerability to poly(ADP-ribose) polymerase (PARP) inhibitors. To search for additional targets whose inhibition is synthetically lethal in BRCA2-deficient backgrounds, we screened two pairs of BRCA2 isogenic cell lines with DNA-repair-focused small hairpin RNA (shRNA) and CRISPR (clustered regularly interspaced short palindromic repeats)-based libraries. We found that BRCA2-deficient cells are selectively dependent on multiple pathways including base excision repair, ATR signaling, and splicing. We identified APEX2 and FEN1 as synthetic lethal genes with both BRCA1 and BRCA2 loss of function. BRCA2-deficient cells require the apurinic endonuclease activity and the PCNA-binding domain of Ape2 (APEX2), but not Ape1 (APEX1). Furthermore, BRCA2-deficient cells require the 5' flap endonuclease but not the 5'-3' exonuclease activity of Fen1, and chemically inhibiting Fen1 selectively targets BRCA-deficient cells. Finally, we developed a microhomology-mediated end-joining (MMEJ) reporter and showed that Fen1 participates in MMEJ, underscoring the importance of MMEJ as a collateral repair pathway in the context of homologous recombination (HR) deficiency.