Identifying Fundamental Mechanisms that Mediate Resistance to Anti-Cancer Therapies

实现长期癌症缓解的一个主要障碍是一些癌细胞抵抗治疗的能力。引人注目的是，人类肿瘤治疗抵抗的基本细胞生物学与赋予许多涡虫物种令人难以置信的再生能力的细胞生物学惊人地相似。在这些扁虫物种中，即使是一小块切除的组织也能再造出一个全新的动物。这种非凡的能力依赖于异质涡虫干细胞库的维持，这些干细胞与癌症干细胞有许多相似之处。例如，这些细胞的一个子集可以耐受高剂量的γ辐射并恢复整个干细胞群。然而，人们对赋予这种耐受性的机制知之甚少，对它们对化疗的耐药性也几乎一无所知。初步研究显示，涡虫对顺铂有耐药性。用80-100μM顺铂治疗纯肠虫诱导的表型大致类似于人类癌症中化学耐药的发展：动物表现出最初的组织损失，随后是再生。基于这些数据和已知的顺铂效应，中心假设是顺铂对干细胞和祖细胞群体的线粒体功能有不同的影响，这不同地改变了标记肿瘤抑制基因的保守染色质特征，即广泛的H3赖氨酸4三甲基化（H3K4me3），增加了细胞异质性，并促进了化疗耐药。本研究的目的是利用人类肿瘤和虫类干细胞群体之间显著的功能相似性，揭示体内代谢和表观遗传调控与化疗耐药发展之间的基本机制，具体目的如下：1)利用线粒体探针、高分辨率成像和生化分析鉴定干细胞和祖细胞群体中顺铂响应性线粒体功能的差异。本研究使用最先进的方法来确定体内干细胞的代谢异质性。2)通过干扰代谢物有效性和测量对H3K4me3、转录异质性和化学耐药的影响，建立代谢、染色质状态和化学耐药之间的机制联系。这项研究将揭示化学耐药中代谢和表观遗传调控之间的关键联系。3)利用已建立的气道类器官模型，评估代谢H3K4me3调控机制在肺癌中的保护作用。本研究将验证耐药肺癌细胞通过降低H3K4me3来响应顺铂诱导的ROS的假设。提出的研究将揭示化学耐药的新机制和靶基因。

A major obstacle to achieving long-term cancer remission is the ability of some cancer cells to resist therapy. Strikingly, the fundamental cell biology underlying therapy resistance in human tumors is remarkably similar to that which confers incredible regenerative capacity in many planarian species. In these flatworm species, even a small piece of excised tissue can recreate an entirely new animal. This remarkable ability relies on the maintenance of a heterogeneous pool of planarian stem cells that bear many similarities to cancer stem cells. For example, a subset of these cells can tolerate high doses of γ-radiation and restore the entire stem cell population. Yet little is known about the mechanisms that confer this tolerance and almost nothing is known about their resistance to chemotherapies. Preliminary research revealed that planarians show resistance to the drug cisplatin. Treatment of planarians with 80-100μM cisplatin induced a phenotype that broadly mimicked the development of chemoresistance in human cancers: animals exhibited an initial loss of tissue followed by regeneration. Based on these data and known effects of cisplatin, the central hypothesis is that cisplatin differentially affects mitochondrial function across the stem and progenitor populations, which differentially alters a conserved chromatin signature that marks tumor suppressor genes i.e., broad H3 lysine 4 trimethylation (H3K4me3), increases cellular heterogeneity, and promotes chemoresistance. The goal of this study is to leverage the remarkable functional similarities between human tumors and the planarian stem cell population to uncover fundamental mechanisms that link the development of chemoresistance to metabolic and epigenetic regulation in vivo through the following specific aims: 1) To identify cisplatin-responsive differences in mitochondrial function in stem and progenitor cell populations using mitochondrial probes, high resolution imaging, and biochemical assays. This study uses state-of the-art approaches to determine the metabolic heterogeneity of stem cells in vivo. 2) To establish mechanistic links between metabolism, chromatin state, and chemoresistance by perturbing metabolite availability and measuring the impact on H3K4me3, transcriptional heterogeneity, and chemoresistance. This study will reveal critical links between metabolic and epigenetic regulation in chemoresistance. 3) To assess the conservation of metabolic H3K4me3 regulatory mechanisms in lung cancer using established airway organoid models. This study will test the hypothesis that resistant lung cancer cells respond to cisplatin-induced ROS by reducing H3K4me3. The proposed research will uncover novel mechanisms and target genes underlying chemoresistance.