Elucidating SAMHD1 in DNA Double-Strand Break Repair

阐明 SAMHD1 在 DNA 双链断裂修复中的作用

• 批准号: 10214575
• 负责人: Baek Kim
• 金额: $ 51.06万
• 依托单位: EMORY UNIVERSITY
• 依托单位国家: 美国
• 财政年份: 2020
• 资助国家: 美国
• 起止时间: 2020-07-11 至 2025-06-30
• 项目状态: 未结题
• 来源: https://reporter.nih.gov/project-details/10214575
• 关键词: Acetylation; Adjuvant; Autoimmune Diseases; Binding; Biochemical; Biological; Biological Models; Breast Cancer Cell; Breast Cancer Patient; Breast Cancer Treatment; Breast Cancer therapy; Cancer Control; Cells; Clinical; Complex; Crystallization; DNA; DNA Damage; DNA Double Strand Break; Data; Deacetylation; Development; Disease; Double Strand Break Repair; Event; Excision; Exhibits; Exposure to; Genetic; Genomic Instability; Goals; HIV-1; Human; In Vitro; Ionizing radiation; Lentivirus; Lysine; Malignant Neoplasms; Maps; Mediating; Metabolism; Molecular Target; Mutation; Outcome; Pathway interactions; Patients; Phenotype; Process; Proteins; Proteomics; Regulation; Resistance; Role; SAM Domain; SIRT1 gene; Signal Transduction; Structure; Testing; Virus Diseases; Virus-like particle; Work; cancer therapy; cancer type; carcinogenesis; chemotherapy; cytotoxic; genome integrity; homologous recombination; improved; in vivo; inhibitor/antagonist; innovation; insight; malignant breast neoplasm; mouse model; neoplastic cell; novel; novel therapeutic intervention; novel virus; nuclease; overexpression; patient derived xenograft model; pseudotoxoplasmosis syndrome; radiation resistance; recombinational repair; recruit; repaired; response; targeted cancer therapy; therapy resistant; tripolyphosphate; tumor

PROJECT SUMMARY Human tumor cells, including breast cancers, exhibit aberrant DNA double-strand break (DSB) repair pathways, which drive genomic instability and carcinogenesis, and most importantly, may serve as novel molecular targets that can be used to reverse treatment resistance phenotypes. However, the precise mechanisms governing the repair of DSBs and how their dysregulation, including upstream signaling in cancers, contributes to tumor cell resistance remains unclear. DSBs are induced by many types of cancer treatments, including ionizing radiation (IR), PARP inhibitors, and chemotherapy. As such, the overarching goal of this proposal is to determine the critical processes by which tumor cells respond to DSBs, as directed by SAMHD1, and how these repair pathways can be exploited to improve breast cancer treatment. SAMHD1 is recognized for its dNTP triphosphohydrolase activity, which restricts HIV-1 and other viral infections and for mutations associated with Aicardi Goutières syndrome (AGS), an autoimmune disorder. SAMHD1 is also overexpressed in 27% of breast cancers. We were the first to identify a novel role for SAMHD1 in promoting the end resection step of homologous recombination (HR) repair independent of its dNTPase activity, which has since been independently validated. Our preliminary data indicate that high SAMHD1 expression is associated with poor survival in breast cancer patients treated with adjuvant IR, suggesting that SAMHD1 overexpression contributes to IR resistance. Using a proteomic approach, we found that SAMHD1 interacts with a number of DNA damage response (DDR) proteins, including CtIP and SIRT1. Our data suggest that SAMHD1 recruits CtIP to DSBs to facilitate DNA end resection and HR independent of its dNTPase activity, and moreover, that SIRT1 directs SAMHD1 function in DSB repair through deacetylation. Finally, we developed a novel therapeutic strategy whereby targeting SAMHD1 for degradation with Vpx, a lentivirus accessory protein, packaged in virus-like particles (VLPs), sensitizes breast cancer cells to DSB-inducing agents. Thus, we hypothesize that in addition to its role in dNTP metabolism, SAMHD1 responds to SIRT1-mediated deacetylation to maintain genome integrity and govern breast cancer treatment resistance by non-catalytically directing DNA end resection and HR through CtIP, which may be exploited to improve breast cancer control. Using innovative genetic, cell biological, biochemical, structural, and in vivo approaches, we propose the following specific aims: 1) Determine the role of SAMHD1 in directing CtIP in DSB repair; 2) Determine the regulation of SAMHD1 in DSB repair by SIRT1; 3) Establish SAMHD1 as a potentially new molecular target for cancer therapy. Completion of this work will define how SAMHD1 non- catalytically directs CtIP function in DSB repair to maintain genome integrity and govern breast cancer treatment resistance, connect the SIRT1 acetylome with SAMHD1-regulated DSB repair, and establish proof of concept for the use of VLPs containing Vpx to target SAMHD1 as a novel therapeutic approach for improving breast cancer control.

项目摘要 人类肿瘤细胞，包括乳腺癌，暴露了异常DNA双链断裂（DSB）修复途径， 驱动基因组不稳定性和致癌作用，最重要的是，可以用作新的分子靶标 可以用来逆转耐药性表型。但是，管理的确切机制 DSB的修复及其功能失调（包括癌症中的上游信号传导）如何有助于肿瘤细胞 阻力仍然不清楚。 DSB由多种类型的癌症治疗诱导，包括电离辐射 （IR），PARP抑制剂和化学疗法。因此，该提案的总体目标是确定 肿瘤细胞按照SAMHD1的指示对DSB响应的关键过程，以及这些维修 可以探索途径以改善乳腺癌治疗。 SAMHD1因其DNTP而被认可 triphosphohydrololase活性，限制了HIV-1和其他病毒感染，并且与与之相关的突变 AicardiGoutières综合征（AGS），一种自身免疫性疾病。 SAMHD1在27％的乳房中也过表达 癌症。我们是第一个确定SAMHD1在促进同源终端切除步骤中的新作用的人 重组（HR）修复独立于其DNTPase活性，此后已被独立验证。 我们的初步数据表明高SAMHD1表达与乳腺癌的生存不良有关 经过调整IR治疗的患者表明SAMHD1过表达有助于IR耐药性。使用 一种蛋白质组学方法，我们发现SAMHD1与许多DNA损伤反应（DDR）蛋白相互作用， 包括CTIP和SIRT1。我们的数据表明SAMHD1将CTIP招募到DSB，以促进DNA终端切除 HR独立于其DNTPase活性，此外，SIRT1指导DSB修复中的SAMHD1功能 通过脱乙酰化。最后，我们制定了一种新颖的理论策略，将SAMHD1定位为 用VPX，慢病毒辅助蛋白降解，包装在病毒样颗粒（VLP），敏感的乳房中 癌细胞诱导DSB诱导剂。我们假设，除了它在DNTP代谢中的作用外， SAMHD1对SIRT1介导的脱乙酰化反应以维持基因组完整性并控制乳腺癌 通过非催化性DNA终端切除和通过CTIP进行HR的治疗耐药性，这可能是 利用以改善乳腺癌的控制。使用创新的遗传，细胞生物学，生化，结构和 在体内方法，我们提出以下特定目的：1）确定SAMHD1在指导CTIP中的作用 在DSB维修中； 2）通过SIRT1确定DSB修复中SAMHD1的调节； 3）将SAMHD1建立为一个 癌症治疗的潜在新分子靶标。这项工作的完成将定义SAMHD1非 - 催化指导DSB修复中的CTIP功能以维持基因组完整性并控制乳腺癌治疗 电阻，将SIRT1乙酰基组与SAMHD1调节的DSB修复联系起来，并建立概念证明 用于使用包含VPX的VLP将SAMHD1作为一种新型治疗方法来改善乳房 癌症控制。