BRAF Mutation in Malignant Astrocytoma Origin, Evolution, and Response to Therapy

恶性星形细胞瘤的起源、演变和治疗反应中的 BRAF 突变

基本信息

批准号：
9134221
负责人：
Charles David James
金额：
$ 35.65万
依托单位：
NORTHWESTERN UNIVERSITY AT CHICAGO
依托单位国家：
美国
项目类别：
财政年份：
2014
资助国家：
美国
起止时间：
2014-09-01 至 2018-08-31
项目状态：
已结题

来源：
https://reporter.nih.gov/project-details/9134221
关键词：
Address Affect Allografting Anaplastic astrocytoma Apoptosis Apoptotic Astrocytes Astrocytoma BRAF gene Basic Science Brain Neoplasms CDKN2A gene Cell division Cells Characteristics Childhood Childhood Brain Neoplasm Clinical Research Complement Cytotoxic Chemotherapy Development Elements Etiology Evolution Gene Mutation Gene Transfer Genetic Genetically Engineered Mouse Growth Heterogeneity Human Implant In Vitro Investigation Lead Malignant - descriptor Malignant Neoplasms Modeling Modification Molecular Molecular Target Mus Mutation Neoplastic Cell Transformation Outcome Parents Patients Phase Process Production Proliferating Radiosurgery Recurrence Regulation Research Resistance Rodent Testing Treatment outcome Tumor Tissue Tumorigenicity base brain cell cell transformation chemotherapy conventional therapy daughter cell effective therapy genetic approach improved in vivo insight interest knock-down metaplastic cell transformation mouse model mutant neoplastic cell nerve stem cell novel novel therapeutics outcome forecast pre-clinical research response self renewing cell self-renewal small hairpin RNA targeted treatment therapy resistant tumor tumor xenograft tumorigenesis tumorigenic

项目摘要

DESCRIPTION (provided by applicant): Many pediatric brain tumors, including malignant astrocytomas (MA), are thought to originate from neural stem cells (NSCs), which, due to the occurrence and accumulation of growth-promoting gene alterations, may give rise to various cell subpopulations, including tumor-initiating cells (TICs). TICs are considered to have increased resistance to conventional therapy for MA, and consequently are important contributors to MA recurrence. Whereas NSCs undergo asymmetric cell divisions (ACD) to self-renew and differentiate at a one-to-one ratio, TICs proliferate and self-renew, and fail to generate fully differentiated cells, suggestive of defective ACD. A mutant, activated form of BRAF, BRAFVE, and concomitant homozygous deletion of CDKN2A, encoding p16, have been found in a significant fraction of pediatric MA. BRAFVE is known to promote proliferation while suppressing normal cellular differentiation. Whether increased production of self-renewing cells through increasing symmetric cell divisions (i.e., decreased ACD) is manifested in association with BRAFVE induced cell transformation is currently unknown. To bridge the gap in our understanding of BRAFVE-induced transformation, and its relationship with ACD, we will examine effects of BRAFVE in p16 deficient NSCs as well as in corresponding p16 deficient astrocytes of mouse and human origin. In addition, we will investigate relationships between BRAFVE-p16 deficient tumors and their adaptation to BRAFVE targeted therapy, with our primary focus directed to tumor cell subpopulation and ACD changes resulting from treatment. Related research will be performed in the context of the following specific aims. Aim 1. Using genetically engineered mouse models (GEMMs), we will determine effects of BRAFVE expression on ACD, proliferation, differentiation, and survival, and association with MA tumorigenesis in NSCs and mature astrocytes. Aim 2. To complement the GEMMs studies in aim 1, we will suppress p16 expression and force BRAFVE expression in human NSCs and normal human astrocytes, using lentiviral shRNA knockdown and BRAFVE gene transfer, respectively. Modified NCS and NHAs as well as MA cells with BRAFVE expression will be characterized, both in vitro and in vivo, for the same characteristics as for the mouse model tumors in aim 1. Aim 3. Investigate BRAFVE tumor cells and tumor tissues, in vitro and in vivo, respectively, for molecular changes, TIC composition, and ACD in association with response to BRAFVE targeted therapy. This research will include comparison of effects when tumors are in a responsive phase to therapy, as well as when they have acquired resistance to therapy, and will utilize both human tumor xenograft and mouse allograft models. Our project will: 1) generate new information regarding the cellular origin of BRAFVE induced MA; 2) provide insight about the molecular mechanisms of neoplastic transformation resulting in brain tumor development; 3) increase our understanding of brain tumor cell subpopulations that are responsible for therapy resistance and tumor recurrence, and in so doing, 4) will ultimately lead to improved treatment outcomes for MA patients.

描述（由申请人提供）：许多小儿脑肿瘤，包括恶性星形胶质细胞（MA），被认为起源于神经干细胞（NSC），由于促进生长基因改变的发生和积累，这可能会引起各种细胞亚群，包括肿瘤发射细胞（TICS）。抽动被认为具有对MA的常规疗法的耐药性，因此是MA复发的重要因素。 NSC经历了不对称的细胞分裂（ACD）以自我更新和以一对比例的比例进行区分，而Tics则增殖和自我更新，并且无法产生完全分化的细胞（暗示ACD）。在大量的小儿MA中发现了一种编码P16的BRAF，BRAFVE和伴随的纯合缺失的突变体形式。已知Brafve可以促进增殖，同时抑制正常的细胞分化。目前未知是否通过增加对称细胞分裂（即ACD降低）来增加自我更新细胞的产生（即ACD降低）。为了弥合我们对Brafve诱导的转化的理解及其与ACD的关系，我们将检查Brafve在p16缺陷NSC以及相应的P16小鼠和人类起源的缺乏的P16中的效果。此外，我们将研究BRAFVE-P16缺乏肿瘤与它们对BRAFVE靶向疗法的适应性之间的关系，我们的主要重点针对肿瘤细胞亚群和治疗导致的ACD变化。相关研究将在以下特定目的的背景下进行。 AIM 1。使用基因工程的小鼠模型（GEMM），我们将确定Brafve表达对ACD，增殖，分化和生存的影响，并与NSC和成熟星形胶质细胞中的MA肿瘤发生结合。目的2。为了补充AIM 1中的GEMMS研究，我们将分别使用慢病毒SHRNA敲低和Brafve基因转移来抑制人类NSC和正常人类星形胶质细胞中P16表达和强迫BRAFVE表达。在体外和体内，将对经过修饰的NC和NHA以及具有BRAFVE表达的MA细胞进行表征，其特征与AIM 1中的小鼠模型肿瘤相同的特征。AIM3。研究Brafve肿瘤细胞和肿瘤组织，体外分子变化，TIC组成和ACD分别与对BRAFVE靶向治疗的反应有关。这项研究将包括肿瘤处于治疗反应阶段以及获得治疗耐药性的反应阶段时的影响，并将同时使用人类肿瘤异种移植和小鼠同种异体移植模型。我们的项目将：1）生成有关Brafve诱导MA的细胞起源的新信息； 2）提供有关肿瘤转化的分子机制导致脑肿瘤发育的见解； 3）增加我们对负责治疗耐药性和肿瘤复发的脑肿瘤细胞亚群的理解，而这样做4）最终将改善MA患者的治疗结果。