Defining and targeting ER quality control dependence in rhabdomyosarcoma

候选人。萨布尼斯医生是一位接受过遗传学和分子生物学培训的儿科肿瘤学家，他的长期 目标是领导一个独立的实验室，定义和定位蛋白质稳态中的脆弱性 儿科肉瘤网络。他已经开始通过第一作者在这一领域确立自己的领导地位 PNAS上发表的关于横纹肌肉瘤(RMS)对HSP70依赖性的详细报道和贡献作者 关于《自然医学》和《自然遗传学》的出版物。这个K08奖项将是他的关键工具 持续的职业发展，在1)设计临床前试验方面提供关键的指导和指导 2)探索癌细胞内质网质量控制机制 颠覆以支持它们的生存，以及3)使用遗传操作和细胞生物读数来审问 肉瘤生物学中的蛋白质平衡。 环境加州大学旧金山分校是一个出色的研究环境，拥有1300名首席研究员和超过500美元的资金 来自国家卫生研究院的100万美元的支持(在所有机构中排名第二)。两位共同导师将帮助萨布尼斯博士实现 他的目标。Trever Bivona博士，医学博士，是一名内科肿瘤学家，在生物学定义Rational方面拥有专业知识 癌基因驱动的实体肿瘤的综合治疗。比沃纳博士拥有广泛的研究支持，包括美国国立卫生研究院 创新者奖和几个R01，并在 在过去五年里。萨布尼斯医生将由医学博士凯文·香农共同指导，他是一名儿科肿瘤学家，曾 我是NCI多位K系列奖项获得者的主要导师。萨布尼斯博士还将会见半- 每年都有一个指导委员会，由比沃纳博士、香农博士、乔纳森·魏斯曼博士和 ER质量控制方面的专家，许多K资助的学员的导师；以及杰出的 儿科肿瘤学临床研究员，将支持他的发现的临床翻译。 研究。尽管最大限度地加强了化疗，但高危RMS患者的预后很差， 突显了对新的、生物驱动的治疗方法的需求。我们发现抑制胞浆蛋白伴侣 HSP70可致命地激活RMS中的未折叠蛋白反应(UPR)，但在其他癌症中则不能。我假设 RMS细胞依赖于HSP70，与其辅助伴侣DNAJC17和ATPase p97一起作用，以降低 ER蛋白通过内质网相关降解(ERAD)加载。因此，RMS中的ERAD抑制定义了一种新的 治疗策略。在目标1中，我们将测试两种药物的药理参数和疗效 小鼠RMS模型的ER质量控制。在目标2中，我们将确定DNAJC17的结构域，这些结构域是 维持ER动态平衡所必需的，并测试HSP70-DNAJC17-p97轴使 Erad，从而确保RMS细胞存活。这些目标将提供关键的分子细节，以了解 我们发现了抑制HSP70的RMS特异性致死性。总体而言，这项工作将促进更广泛的努力 在肉瘤蛋白抑制网络中发现治疗靶点，这将是未来R01提案的基础。 好了！

Candidate. Dr. Sabnis is a pediatric oncologist with training in genetics and molecular biology whose long-term goal is to lead an independent laboratory defining and targeting vulnerabilities in the protein homeostasis networks of pediatric sarcomas. He has begun to establish himself as a leader in this field through a first author publication in PNAS detailing HSP70 dependence in rhabdomyosarcoma (RMS) and contributing authorship on publications in Nature Medicine and Nature Genetics. This K08 award will be a critical vehicle for his ongoing career development, providing key mentorship and instruction in 1) designing preclinical trials to enable clinical translation of bench research, 2) probing the ER quality control mechanisms cancer cells subvert to support their survival, and 3) using genetic manipulation and cell biologic readouts to interrogate proteostasis in sarcoma biology. Environment. UCSF is an outstanding research environment with 1300 principal investigators and over $500 million in support from the NIH (ranking 2nd among all institutions). Two co-mentors will help Dr. Sabnis achieve his aims. Dr. Trever Bivona, MD PhD, is a medical oncologist with expertise in biologically defining rational polytherapy for oncogene-driven solid tumors. Dr. Bivona has extensive research support including an NIH Innovator’s Award and several R01s, and has mentored five post-doctoral fellows into independent positions in the last five years. Dr. Sabnis will be co-mentored by Dr. Kevin Shannon, MD, a pediatric oncologist who has been the primary mentor for multiple K-series award recipients from the NCI. Dr. Sabnis will also meet semi- annually with a mentoring committee, comprised of Dr. Bivona; Dr. Shannon; Dr. Jonathan Weissman, an expert in ER quality control and mentor to many K-supported trainees; and Dr. Kate Matthay, a pre-eminent pediatric oncology clinical researcher who will support the clinical translation of his discoveries. Research. High-risk RMS patients have dismal outcomes despite maximally intensified chemotherapy, highlighting a need for new, biology-driven treatments. We found that inhibiting the cytosolic protein chaperone HSP70 lethally activates the unfolded protein response (UPR) in RMS, but not in other cancers. I hypothesize that RMS cells rely on HSP70, acting together with its co-chaperone DNAJC17 and the ATPase p97, to lower ER protein load through ER-associated degradation (ERAD). ERAD inhibition in RMS thus defines a novel therapeutic strategy. In aim 1, we will test the pharmacologic parameters and efficacy of two drugs that disrupt ER quality control in murine RMS models. In aim 2, we will identify the structural domains of DNAJC17 that are necessary to maintain ER homeostasis, and test the hypothesis that this HSP70-DNAJC17-p97 axis enables ERAD and thereby ensures RMS cell survival. These aims will provide crucial molecular detail into the basis of the RMS-specific lethality of HSP70 inhibition we discovered. Overall, this work will catalyze a broader effort to discover therapeutic targets in sarcoma proteostasis network that will be the basis for future R01 proposals. !