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: 10418774
• 负责人: Baek Kim
• 金额: $ 50.03万
• 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/10418774
• 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; 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.

项目概要 人类肿瘤细胞，包括乳腺癌，表现出异常的 DNA 双链断裂 (DSB) 修复途径， 导致基因组不稳定和致癌，最重要的是，可以作为新的分子靶标 可用于逆转治疗耐药表型。然而，精确的机制控制 DSB 的修复以及它们的失调（包括癌症中的上游信号传导）如何导致肿瘤细胞 抵抗力仍不清楚。 DSB 由许多类型的癌症治疗引起，包括电离辐射 (IR)、PARP 抑制剂和化疗。因此，本提案的总体目标是确定 SAMHD1 指导下肿瘤细胞响应 DSB 的关键过程，以及这些过程如何修复 可以利用这些途径来改善乳腺癌的治疗。 SAMHD1 因其 dNTP 得到认可 三磷酸水解酶活性，限制 HIV-1 和其他病毒感染以及与 Aicardi Goutières 综合征 (AGS)，一种自身免疫性疾病。 SAMHD1 在 27% 的乳腺组织中也过度表达 癌症。我们是第一个发现 SAMHD1 在促进同源末端切除步骤中的新作用的人。 重组 (HR) 修复独立于其 dNTPase 活性，此后已得到独立验证。 我们的初步数据表明 SAMHD1 高表达与乳腺癌的生存率较低有关 接受辅助 IR 治疗的患者，表明 SAMHD1 过度表达有助于 IR 抵抗。使用 通过蛋白质组学方法，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 末端切除 和 HR 与其 dNTPase 活性无关，此外，SIRT1 在 DSB 修复中指导 SAMHD1 功能 通过脱乙酰化。最后，我们开发了一种新的治疗策略，针对 SAMHD1 Vpx 是一种慢病毒辅助蛋白，包装在病毒样颗粒 (VLP) 中，可降解，使乳腺敏感 癌细胞到 DSB 诱导剂。因此，我们假设除了它在 dNTP 代谢中的作用外， SAMHD1 对 SIRT1 介导的脱乙酰化作出反应，以维持基因组完整性并控制乳腺癌 通过非催化引导 DNA 末端切除和通过 CtIP 进行 HR 来消除治疗耐药性，这可能是 用于改善乳腺癌控制。利用创新的遗传、细胞生物学、生化、结构和 体内方法，我们提出以下具体目标：1）确定SAMHD1在指导CtIP中的作用 DSB 修复； 2)确定SIRT1对SAMHD1在DSB修复中的调节作用； 3) 将 SAMHD1 建立为 癌症治疗的潜在新分子靶点。这项工作的完成将定义 SAMHD1 如何非 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 乙酰组与 SAMHD1 调节的 DSB 修复连接起来，并建立概念验证 使用含有 Vpx 的 VLP 靶向 SAMHD1 作为改善乳腺的新型治疗方法 癌症控制。