Mechanisms by which LSD1 Promotes Neuroendocrine Differentiation and Small Cell Lung Cancer

项目摘要/摘要 摘要小细胞肺癌是一种高度恶性的神经内分泌肿瘤，目前尚无明确的靶向治疗方法。 治疗。组蛋白去甲基酶抑制剂LSD1目前正在小细胞肺癌进行临床试验，灵感来自Strong 临床前数据表明，一些SCLC对LSD1抑制具有高度和选择性的敏感性。然而， 只有少数SCLC对LSD1抑制高度敏感，而大多数SCLC是天生耐药的。这个 一些SCLC高度依赖LSD1的分子基础尚不清楚。了解 一些SCLC对LSD1抑制剂高度敏感的原因机制可以识别预测 选择更有可能对LSD1抑制剂有反应的患者或确定合理组合策略的生物标记物 使LSD1抑制剂更有效。 使用无偏正选择CRISPR/Cas9与LSD1抑制剂一起进行功能丧失筛查，我们有 发现了LSD1抑制剂调节小细胞肺癌的新的致病机制，包括 LSD1对小细胞肺癌神经内分泌分化的调控作用 LSD1和LSD1抑制剂对LSD1的敏感性，也确定了一个合理的组合策略来克服 对LSD1抑制剂的耐药性。 我们建议的广泛的长期目标是阐明LSD1 促进小细胞肺癌肿瘤发生和神经内分泌分化(目标1和3)，并测试合理的组合 使LSD1抑制在小细胞肺癌中更有效的策略(目标2)。为了做到这一点，我们将在体外结合 机械方法严格剖析LSD1驱动小细胞肺癌增殖和 基因工程体内免疫活性小细胞肺癌诱导神经内分泌分化 我们用CRISPR/Cas9建立的小鼠模型(GEMM)，可以用来在肿瘤起始时删除LSD1 并研究其在小细胞肺癌发生发展中的作用。使用这些LSD1等基因SCLC GEMM，我们将询问 LSD1的缺失如何阻止神经内分泌分化、促进谱系可塑性和增加肿瘤 免疫原性。总之，这些研究将为小细胞肺癌如何利用LSD1提供重要的生物学见解 推动肿瘤发生和神经内分泌分化，这最终可能导致发现 选择更有可能对LSD1抑制剂有反应的患者的预测性生物标志物。最后，这项研究可以 为合理的联合治疗策略提供临床前基础，使LSD1抑制剂 对小细胞肺癌患者有效。

PROJECT SUMMARY/ABSTRACT Small cell lung cancer (SCLC) is a high-grade neuroendocrine tumor currently without any approved targeted therapies. Inhibitors of the histone demethylase LSD1 are currently in clinical trials in SCLC inspired by strong preclinical data demonstrating that some SCLCs are highly and selectively sensitive to LSD1 inhibition. However, only a minority of SCLCs are highly sensitive to LSD1 inhibition, while most SCLCs are inherently resistant. The molecular basis for why some SCLCs are highly dependent on LSD1 is not understood. Understanding the causative mechanisms for why some SCLCs are highly sensitive to LSD1 inhibitors could identify predictive biomarkers to select patients more likely to respond to LSD1 inhibitors or identify rational combination strategies to make LSD1 inhibitors more effective. Using unbiased positive selection CRISPR/Cas9 loss of function screening with LSD1 inhibitors, we have uncovered novel causative mechanisms by which LSD1 inhibitors regulate SCLC, which include mechanisms by which LSD1 regulates neuroendocrine differentiation in SCLC, target genes that are bound and repressed by LSD1 and required for LSD1 inhibitor sensitivity, and also identified a rational combination strategy to overcome resistance to LSD1 inhibitors. The broad long-term objective of our proposal is to elucidate the molecular mechanisms by which LSD1 promotes SCLC tumorigenesis and neuroendocrine differentiation (aims 1 and 3), and test a rational combination strategy to make LSD1 inhibition more effective in SCLC (aim 2). To accomplish this, we will combine in vitro mechanistic approaches to rigorously dissect the mechanisms by which LSD1 drives SCLC proliferation and neuroendocrine differentiation with an in vivo autochthonous immunocompetent SCLC genetically-engineered mouse model (GEMM) that we developed using CRISPR/Cas9 that can be used to delete LSD1 at tumor initiation and study its function during SCLC tumorigenesis. Using these LSD1 isogenic SCLC GEMMs, we will interrogate how loss of LSD1 blocks neuroendocrine differentiation, promotes lineage plasticity, and increases tumor immunogenicity. Together, these studies will provide important biological insights into how SCLCs utilize LSD1 to drive tumorigenesis and neuroendocrine differentiation, which ultimately could lead to the identification of predictive biomarkers to select patients more likely to respond to LSD1 inhibitors. Lastly, this research could provide the preclinical foundation for a rational combination therapeutic strategy to make LSD1 inhibitors more effective for SCLC patients.