Functional role and clinical relevance of mutated SMARCB1/INI1 protein in atypical teratoid/rhabdoid tumors (AT/RT)

突变 SMARCB1/INI1 蛋白在非典型畸胎瘤/横纹肌样瘤 (AT/RT) 中的功能作用和临床相关性

• 批准号: 390523101
• 负责人: Professor Dr. Martin Hasselblatt
• 金额: --
• 依托单位: Institut für Neuropathologie
• 依托单位国家: 德国
• 项目类别: Research Grants
• 财政年份: 2017
• 资助国家: 德国
• 起止时间: 2016-12-31 至 2020-12-31
• 项目状态: 已结题
• 来源: https://gepris.dfg.de/gepris/projekt/390523101?language=en
• 关键词: Functional; role; clinical; relevance; mutated

The SWI/SNF chromatin remodeling complex modulates chromatin structure and regulates gene transcription. Genetic alterations affecting members of the SWI/SNF complex play a critical role in developmental disorders and cancer. The SMARCB1/INI1 protein represents a core member of the SWI/SNF complex. Atypical teratoid/rhabdoid tumor (AT/RT) is a pediatric brain tumor characterized by mutations of the SMARCB1 gene. AT/RT is a highly aggressive tumor with dismal prognosis, but some patients also respond well to therapy and even experience long-term survival. Molecular factors that might explain differences in biological tumor behavior remain to be identified. Preliminary findings from our group suggest that lower proliferative activity and longer overall survival in a subgroup of AT/RT could be explained by the presence of a truncated SMARCB1/INI1 protein, which might have some residual function. Within the proposed DFG project, we will systematically explore the functional role and clinical relevance of mutated SMARCB1/INI1 protein in AT/RT. In particular, (1) we aim at a better understanding how various SMARCB1 mutations encountered in AT/RT affect SMARCB1/INI1 protein expression, (2) explore how the presence of mutated SMARCB1/INI1 proteins affects tumor biology and (3) investigate if the presence of mutated SMARCB1/INI1 proteins might explain the epigenetic and clinical heterogeneity of AT/RT. To this end, expression of mutated SMARCB1/INI1 protein will be examined in a large series of AT/RT tissue samples using a panel of antibodies directed against various epitopes of the SMARCB1/INI1 protein. Next, the functional role of mutated SMARCB1/INI1 protein will be studied in rhabdoid tumor cells using site-directed mutagenesis and transient transfection. The functional consequences of re-expression of mutant SMARCB1/INI1 proteins as compared to wildtype SMARCB1/INI1 protein (control) on proliferation and apoptosis will be examined. Finally, the clinical relevance of SMARCB1 mutations causing less aggressive tumor behavior in vitro will be examined in patients with AT/RT from the European Rhabdoid Tumor Registry EU RHAB. The effect on progression-free survival and overall survival will be examined also taking into account other important clinical and molecular factors such as age, tumor location and germ line mutation status. The results from this project will contribute to a better understanding of SMARCB1/INI1 protein function in AT/RT, but will also have implications for other tumors with SWI/SNF complex dysfunction. In the long term, they are expected to aid the development of prognostic markers and better treatment stratification for children with AT/RT.

SWI/SNF 染色质重塑复合物调节染色质结构并调节基因转录。影响 SWI/SNF 复合体成员的基因改变在发育障碍和癌症中发挥着关键作用。 SMARCB1/INI1 蛋白代表 SWI/SNF 复合体的核心成员。非典型畸胎瘤样/横纹肌样瘤 (AT/RT) 是一种以 SMARCB1 基因突变为特征的儿科脑肿瘤。 AT/RT 是一种高度侵袭性的肿瘤，预后较差，但一些患者对治疗反应良好，甚至可以长期生存。可能解释生物肿瘤行为差异的分子因素仍有待确定。我们小组的初步研究结果表明，AT/RT 亚组中较低的增殖活性和较长的总生存期可以通过截短的 SMARCB1/INI1 蛋白的存在来解释，该蛋白可能具有一些残留功能。在拟议的 DFG 项目中，我们将系统地探索突变 SMARCB1/INI1 蛋白在 AT/RT 中的功能作用和临床相关性。特别是，（1）我们的目标是更好地了解 AT/RT 中遇到的各种 SMARCB1 突变如何影响 SMARCB1/INI1 蛋白表达，（2）探索突变 SMARCB1/INI1 蛋白的存在如何影响肿瘤生物学，以及（3）研究是否SMARCB1/INI1 蛋白突变的存在可能解释了 AT/RT 的表观遗传和临床异质性。为此，将使用一组针对 SMARCB1/INI1 蛋白各种表位的抗体在大量 AT/RT 组织样本中检查突变 SMARCB1/INI1 蛋白的表达。接下来，将使用定点诱变和瞬时转染研究突变 SMARCB1/INI1 蛋白在横纹肌样肿瘤细胞中的功能作用。将检查与野生型 SMARCB1/INI1 蛋白（对照）相比，突变型 SMARCB1/INI1 蛋白重新表达对增殖和凋亡的功能影响。最后，将在来自欧洲横纹肌样肿瘤登记处 EU RHAB 的 AT/RT 患者中检查 SMARCB1 突变导致体外侵袭性肿瘤行为减弱的临床相关性。还将检查对无进展生存期和总生存期的影响，同时考虑其他重要的临床和分子因素，例如年龄、肿瘤位置和种系突变状态。该项目的结果将有助于更好地了解 SMARCB1/INI1 蛋白在 AT/RT 中的功能，但也将对具有 SWI/SNF 复合物功能障碍的其他肿瘤产生影响。从长远来看，它们有望帮助开发 AT/RT 儿童的预后标志物和更好的治疗分层。