The role of SMARCAL1 in glioma telomere maintenance.

SMARCAL1 在神经胶质瘤端粒维持中的作用。

• 批准号: 10301195
• 负责人: Matthew Waitkus
• 金额: $ 15.21万
• 依托单位: DUKE UNIVERSITY
• 依托单位国家: 美国
• 财政年份: 2022
• 资助国家: 美国
• 起止时间: 2022-02-20 至 2025-01-31
• 项目状态: 未结题
• 来源: https://reporter.nih.gov/project-details/10301195
• 关键词: ATRX gene; Actins; Adult; Adult Glioblastoma; Architecture; Astrocytes; Astrocytoma; Brain Neoplasms; Cancer cell line; Cell Cycle; Cell Line; Cell Maintenance; Cell Proliferation; Cells; Cessation of life; Childhood Glioma; Chromatin; Chromosomes; DNA; DNA Damage; DNA Sequence; DNA Sequence Alteration; DNA biosynthesis; DNA replication fork; Data; Enzymes; Epigenetic Process; Genes; Genetic Engineering; Glioblastoma; Glioma; Growth; Hela Cells; Histones; Human; Lead; Length; Malignant Glioma; Malignant Neoplasms; Malignant neoplasm of brain; Modeling; Molecular; Molecular Chaperones; Mutation; Pathologic; Pathway interactions; Patients; Phenotype; Play; Process; Proteins; Publishing; RNA; RNA Interference; Recurrence; Reverse Transcription; Role; Site; Structure; TP53 gene; Telomerase; Telomere Maintenance; Telomere Pathway; Testing; Therapeutic; Tumorigenicity; United States; Xenograft procedure; aggressive therapy; base; cancer cell; cancer type; design; extrachromosomal DNA; genetically modified cells; glioma cell line; helicase; homologous recombination; knock-down; loss of function; loss of function mutation; mouse model; mutant; novel; novel strategies; osteosarcoma; promoter; replication stress; sarcoma; telomere; therapeutic target; virtual

PROJECT SUMMARY Gliomas are the most common primary malignant brain tumors in adults and account for over 14,000 deaths annually in the United States. Glioblastoma (GBM, grade IV glioma) is the most common and deadly glioma subtype and is associated with a median overall survival of only ~15 months with aggressive therapy. Telomere maintenance mechanisms are a hallmark of cancer and are required to enable replicative immortality of malignant cells, including gliomas. To maintain telomeres, the majority of gliomas use the enzyme telomerase, which uses an RNA template and reverse transcription to extend telomeric repeats at the ends of chromosomes. In contrast, a subset of gliomas employs telomerase-independent mechanisms, termed Alternative Lengthening of Telomeres (ALT). ALT uses homologous recombination to maintain telomere length and is characterized by increased replicative stress in telomere regions and remodeling of telomeric chromatin architecture to an epigenetic state that is permissive to homologous recombination. ~10% of GBM cases and virtually all progressive grade II/III IDH-mutant astrocytomas harbor genetic alterations involved in the induction of ALT. In addition to ATRX mutations, we recently identified recurrent loss-of-function mutations in the SMARCAL1 (SWI/SNF-related, matrix-associated, actin-dependent regulator of chromatin, subfamily A-like1) gene as novel genetic mutations associated with the ALT phenotype in IDH-wildtype – TERT promoter wild-type GBM. SMARCAL1 encodes an annealing helicase that localizes to sites of DNA damage and replication stress and resolves stalled replication fork structures to facilitate fork progression within difficult-to-replicate DNA sequences, such as telomeres. Recent studies indicate that SMARCAL1 localizes to telomeric DNA in ALT- positive cancer cells with native ATRX-inactivating mutations and that SMARCAL1 helicase activity suppresses markers of replication stress and DNA damage at telomeres. Based on these observations, we hypothesize that SMARCAL1 activity is essential for resolving replication stress at telomeric regions and SMARCAL1 loss-of- function leads to an increase in unresolved replication fork collapse and DNA damage at telomeres in a manner that is permissive to homologous recombination and ALT. In Aim 1 we will use genetically engineered cell lines and cancer cell lines with native SMARCAL1 mutations to identify specific ALT pathway components required for telomere synthesis and cellular immortalization in the context of SMARCAL1 loss-of-function mutations. In Aim 2, we will use patient-derived glioma cell lines and xenografts to determine the extent to which SMARCAL1 helicase activity resolves replication stress at telomeres in ATRX-mutant GBM cell lines using ALT. Collectively, the proposed studies are expected to significantly advance our understanding of the role of SMARCAL1 in GBM telomere maintenance and are designed to establish proof of concept for therapeutic targeting of SMARCAL1 in ALT-positive gliomas harboring ATRX mutations.

项目摘要 神经胶质瘤是成人最常见的主要原发性恶性脑肿瘤，占14,000多人死亡 胶质母细胞瘤（GBM，IV Glioma）是最常见和致命的神经胶质瘤 亚型，与侵略性疗法的总体生存率仅约15个月相关。端粒 维护机制是癌症的标志，需要使 恶性细胞，包括神经胶质瘤。为了维持端粒，大多数胶质瘤使用酶端粒酶， 它使用RNA模板和逆转录来扩展染色体末端的远程重复序列。 相比之下，Gliomas员工端粒酶独立的机制的一部分被称为替代性延长 端粒（alt）。 ALT使用同源重组来维持端粒长度，其特征是 端粒区域的复制应力增加，并重塑远程染色质结构 具有同源重组的表观遗传状态。 〜GBM案件的10％，几乎全部 进行性II级/III级IDH突变的星形胶质细胞瘤携带的遗传改变涉及ALT的诱导。在 除了ATRX突变外，我们最近确定了SMARCAL1中的复发功能丧失突变 （SWI/SNF相关，基质相关，肌动蛋白依赖性调节剂，染色质，亚家族A-like1）作为新颖的基因 IDH-WildType - TERT启动子野生型GBM中与ALT表型相关的遗传突变。 SMARCAL1编码一种退火解旋酶，该解放酶定位于DNA损伤部位和复制应力和 解决停滞的复制叉结构，以促进难以复制的DNA内的叉进程 序列，例如端粒。最近的研究表明，smarcal1本地化为远程dna 天然ATRX灭活突变的阳性癌细胞，并且Smarcal1旋转酶活性抑制 端粒的复制应力和DNA损伤的标记。基于这些观察，我们假设 SMARCAL1活性对于在远程定位区域解决复制应力和SMARCAL1的重复应力至关重要。 功能会导致未解决的复制叉塌陷和端粒处的DNA损伤的增加 这是同源重组和ALT的允许。在AIM 1中，我们将使用一般工程的单元线 和具有天然Smarcal1突变的癌细胞系，以识别所需的特定ALT途径成分 在Smarcal1功能丧失突变的背景下，用于端粒合成和细胞永生化。在 AIM 2，我们将使用患者来源的神经胶质瘤细胞系和异种移植物来确定smarcal1的程度 使用ALT使用ALTX突变的GBM细胞系中的端粒中的复制应力。共同 预计拟议的研究将显着提高我们对Smarcal1在GBM中的作用的理解 端粒维护，旨在建立概念验证，以靶向Smarcal1的治疗靶向 具有ATRX突变的Alt阳性神经瘤。