Targeting PLK1 signaling for the treatment of fibrolamellar carcinoma

项目总结 纤维板层癌(FLC)是一种儿童肝癌，病死率高。FLC患者的临床表现 通常表现为晚期疾病，因为没有早期预警迹象。因此，通过手术切除来治愈 几乎不可能实现。此外，众所周知，肝癌对化疗和其他靶向治疗具有耐药性。 目前被批准用于肝癌，导致5年存活率仅为30%。新的治疗策略 中和FLC中出错的分子信号事件是迫切需要的。FLC的特征是 融合事件导致一种新的嵌合蛋白，该嵌合蛋白将DNAJ的N末端结构域与催化 肝细胞中的蛋白激酶A亚单位(PKAc)。然而，DNAJ-PKAc的潜在机制 FLC肿瘤生长的驱动因素尚不清楚。 该项目的总体目标是应用公正的基于系统的 一种识别和验证调控DNAJ-PKAc生长的可药物信号网络的方法 表达FLC细胞，并揭示DNAJ-PKAc嵌合蛋白如何驱动FLC的机制。 缺乏临床前模型，如永生化的原代人类FLC细胞系，已经排除了许多 调查人员。我们的实验室已经建立了三个新的模型系统来解决这一重大差距：患者派生的 携带FLC基因融合的细胞系、器官型培养和患者来源的异种移植(PDX)小鼠。利用 在这些模型系统中，我们进行了基于系统药理学的功能性激酶抑制剂的筛选 FLC细胞和正常肝细胞。我们发现并确认了PLK1蛋白在细胞周期中的重要作用。 FLC细胞生长情况。PLK1的基因缺失或药物抑制选择性地抑制肿瘤的生长 多个患者来源的FLC细胞系和FLC器官型组织切片的生存能力。此外，对 在PDX模型中，含有PLK1抑制剂的FLC肿瘤显著抑制了肿瘤的生长。PLK激酶是关键 中心体成熟和有丝分裂的调节因子。后续实验表明DNAJ-PKAc嵌合体 定位于中心体，在那里它与PLK1物理上相互作用。因此，我们假设 FLC细胞对PLK抑制的敏感性源于DNAJ-PKAc融合蛋白对PLK抑制的定位 中心体，其与PLK1复合体的结合，从而增强PLK1的激活并促进 有丝分裂进程。我们建议：1.揭示dnj-pkac融合改变plk1的分子机制。 激活和功能，以及2.评价临床级别的plk1抑制剂单独和联合使用的疗效。 在临床前模型中进行化疗。功能分析将突出以下机制的见解 DNAJ-PKAc驱动FLC肿瘤进展和PLK1信号复合体在FLC生存中的作用，因此 加深了我们对疾病发病机制的认识。我们由古杰拉尔博士组成的跨学科团队， Scott和Yeung代表着紧密的合作，带来了系统生物学、PKA生物化学和国家- 最先进的人类来源的FLC癌症模型来解决这种致命的疾病。我们的发现具有翻译性 因为它们将为靶向维持FLC肿瘤生存的关键信号节点提供理论基础。

PROJECT SUMMARY Fibrolamellar carcinoma (FLC) is a childhood liver cancer with a high case mortality rate. Patients with FLC typically present with advanced disease, as there are no early warning signs. Thus, a cure by surgical resection is rarely attainable. In addition, FLCs are notoriously resistant to chemotherapies and other targeted therapies currently approved for liver cancer, leading to a 5-year survival of just 30%. New therapeutic strategies that counteract the molecular signaling events that go awry in FLC are urgently needed. FLC is characterized by a fusion event resulting in a novel chimeric protein that joins the N-terminal domain of DNAJ with the catalytic subunit of protein kinase A (PKAc) in hepatocytes. However, the underlying mechanism by which DNAJ-PKAc drives FLC tumor growth remains unknown. This project's overall goal is to apply an unbiased systems-based approach to identify and validate druggable signaling networks that regulate the growth of DNAJ-PKAc- expressing FLC cells and uncover a mechanistic understanding of how DNAJ-PKAc chimeric protein drives FLC. The paucity of preclinical models such as immortalized primary human FLC cell lines has precluded many investigators. Our lab has established three new model systems to address this significant gap: patient-derived cell lines bearing the FLC gene fusion, organotypic cultures, and patient-derived xenograft (PDX) mice. Utilizing these model systems, we carried out a systems-pharmacology-based functional kinase inhibitor screening in FLC cells and normal hepatocytes. We identified and confirmed the role of PLK1 kinases as essential for the growth of FLC cells. Genetic depletion or pharmacological inhibition of PLK1 selectively reduces the growth of multiple patient-derived FLC cell lines and the viability of FLC organotypic tissue slices. Further, treatment of the FLC tumor with PLK1 inhibitor significantly reduced the tumor growth in the PDX model. PLK kinases are key regulators of centrosome maturation and mitosis. Follow-up experiments suggest that DNAJ-PKAc chimera localizes to the centrosomes where it physically interacts with PLK1.Thus, we hypothesize that the heightened sensitivity of the FLC cells to PLK inhibition stems from the localization of the DNAJ-PKAc fusion protein to the centrosome, its association with the PLK1 complex, thereby enhancing the activation of PLK1 and promoting mitotic progression. We propose to 1. uncover molecular mechanisms of how DNAJ-PKAc fusion alters PLK1 activation and function, and 2. evaluate the efficacy of clinical-grade PLK1 inhibitors alone and in combination with chemotherapy in preclinical models.Functional analyses will highlight the mechanistic insights by which DNAJ-PKAc drives FLC tumor progression and the role of the PLK1 signaling complex in FLC survival, thus deepening our understanding of disease pathogenesis. Our cross-disciplinary team consisting of Drs. Gujral, Scott, and Yeung represent a cohesive collaboration that brings systems biology, PKA biochemistry, and state- of-art human-derived FLC cancer models to address this deadly disease. Our findings have translational significance as they will provide a rationale for targeting critical signaling nodes that sustain FLC tumors' survival.