The role of SMARCAL1 in glioma telomere maintenance.

SMARCAL1 在神经胶质瘤端粒维持中的作用。

基本信息

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
项目类别：
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

项目摘要

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.

项目概要神经胶质瘤是成人最常见的原发性恶性脑肿瘤，导致 14,000 多人死亡胶质母细胞瘤（GBM，IV 级胶质瘤）是美国每年最常见和致命的胶质瘤。端粒亚型，且与积极治疗的中位总生存期仅约 15 个月相关。维持机制是癌症的一个标志，需要使癌症能够复制永生。恶性细胞，包括神经胶质瘤，为了维持端粒，大多数神经胶质瘤使用端粒酶，它使用 RNA 模板和逆转录来延长染色体末端的端粒重复序列。相比之下，神经胶质瘤的一个子集采用不依赖端粒酶的机制，称为替代延长端粒 (ALT) 使用同源重组来维持端粒长度，其特点是端粒区域复制压力增加以及端粒染色质结构重塑表观遗传状态允许约 10% 的 GBM 病例和几乎所有病例发生同源重组。进行性 II/III 级 IDH 突变型星形细胞瘤含有与 ALT In 诱导相关的基因改变。除了 ATRX 突变之外，我们最近还发现了 SMARCAL1 中反复出现的功能丧失突变（SWI/SNF 相关、基质相关、肌动蛋白依赖性染色质调节因子、亚家族 A-like1）基因为新基因与 IDH 野生型 - TERT 启动子野生型 GBM 中 ALT 表型相关的基因突变。 SMARCAL1 编码一种退火解旋酶，定位于 DNA 损伤和复制应激位点，解决停滞的复制叉结构，以促进难以复制的 DNA 中的复制叉进展最近的研究表明 SMARCAL1 定位于 ALT- 中的端粒 DNA。具有天然 ATRX 失活突变且 SMARCAL1 解旋酶活性抑制的阳性癌细胞基于这些观察，我们发现了端粒复制应激和 DNA 损伤的标记。 SMARCAL1 活性对于解决端粒区域的复制应激和 SMARCAL1 丢失至关重要功能以某种方式导致未解决的复制叉崩溃和端粒 DNA 损伤增加允许同源重组和 ALT 在目标 1 中，我们将使用基因工程细胞系。和具有天然 SMARCAL1 突变的癌细胞系，以确定所需的特定 ALT 通路成分用于 SMARCAL1 功能丧失突变背景下的端粒合成和细胞永生化。目标 2，我们将使用患者来源的胶质瘤细胞系和异种移植物来确定 SMARCAL1 的程度解旋酶活性利用 ALT 解决 ATRX 突变 GBM 细胞系中端粒的复制应激。拟议的研究预计将显着增进我们对 SMARCAL1 在 GBM 中的作用的理解端粒维持，旨在建立 SMARCAL1 治疗靶向的概念证明携带 ATRX 突变的 ALT 阳性神经胶质瘤。