TRANSCRIPTIONAL REPROGRAMMING OF ESR1 MUTANT BREAST CANCER IN METASTASIS AND TREATMENT RESISTANCE

项目摘要 在美国，多达八分之一的女性会在一生中患上浸润性乳腺癌，70%-80%的患者会患上浸润性乳腺癌 雌激素受体阳性(ER+)。这些癌症依赖于荷尔蒙信号，允许使用 内分泌治疗(ET)，包括芳香酶抑制剂，降低雌激素水平，或靶向 ER本身使用调制器和降解器。虽然这些疗法降低了高达40%的死亡率，但这种疾病 由于ET耐药，常常复发和进展为转移。抗药性的主要机制是 雌激素受体基因(ESR1)突变的获得。这些突变赋予结构性激活 呃，表现出对内分泌治疗的敏感性降低，并在高达38%的转移瘤中发现。的确有 目前还没有针对携带这些突变的患者的特效药，这应该是临床上的优先事项。 考虑到它们在转移性疾病中的普遍存在。福库实验室发现了不同的转录变化 原发和转移部位肿瘤之间，以及耐药ESR1突变体和野生型ER之间 细胞。在一项对900名转移性乳腺癌患者的研究中，ESR1突变与其他 ER+乳腺癌突变包括DNA水平上的Myc和MAPK通路，但Fuqua的最新数据 实验室和其他机构表明，ESR1突变激活了相同的生长和增殖途径 转录水平。考虑到ESR1突变体的转移倾向和治疗耐药，这项提议 中心假设是ESR1突变产生转录重编程的表型促进 乳腺癌中的转移和ET耐药。这项提议的理由是，确定 ESR1转移瘤和耐药肿瘤的转录变化提高了对ESR1突变的理解 疾病进化。通过针对在这一进化过程中发生的转录变化，患者可以保持 ET时间延长，无转移生存期延长。为了检验这一中心假设，我们提出了两个具体目标。 目的1：在含有ESR1突变的肿瘤中，伴随着什么克隆和转录变化 受到外周压力的影响？这一目标使用计算方法来识别克隆进化和转录 利用单细胞RNA/DNA序列和芯片序列研究肿瘤转移的驱动因素。转录驱动程序将通过以下方式进行验证 FDA批准的这些候选药物的抑制剂与ET联合使用，采用体外试验。目标2：Do ET 增强ESR1突变的获取，促进亚克隆进化以驱动治疗耐药？这一目标 通过开发在长期ET期间获得的ESR1突变的模型并使用 通过结合单细胞DNA-SEQ和RNA-SEQ来确定克隆进化的计算生物学 以及ET耐药的转录驱动候选基因。将使用SELECTIONAL验证候选司机 体外和体内与ET联合使用的抑制剂。这项提议的结果将对 该领域为突变特异性治疗靶点奠定了基础，通过以下方式减缓疾病的进展 通过提高治疗的耐受性延长无转移生存期和ET敏感性。

Project Summary Up to 1 in 8 women in the United States will develop invasive breast cancer in their lifetime, with 70-80% of cases being estrogen receptor positive (ER+). These cancers rely on hormonal signaling, allowing for treatment with endocrine therapy (ET), including inhibitors of the aromatase enzyme, lowering estrogen levels, or targeting of the ER itself using modulators and degraders. While these therapies reduce mortality by up to 40%, the disease often recurs and progresses to metastasis as a result of ET resistance. The main mechanism of resistance is the acquisition of estrogen receptor gene (ESR1) mutations. These mutations confer constitutive activation to ER, exhibiting reduced sensitivity to endocrine therapies, and are found in up to 38% of metastases. There is currently no approved therapy specific to patients harboring these mutations, which should be a clinical priority given their prevalence in metastatic disease. The Fuqua laboratory has identified distinct transcriptional changes between primary and metastatic site tumors, and between therapy-resistant ESR1 mutants and wild type ER cells. In a study of 900 metastatic breast cancer patients, ESR1 mutations were mutually exclusive with other ER+ breast cancer mutations including Myc and MAPK pathways at the DNA level, but current data in the Fuqua laboratory and others indicates ESR1 mutations activate these same growth and proliferation pathways at the transcriptional level. Given the ESR1 mutant’s proclivity for metastasis and therapy-resistance, this proposal’s central hypothesis is ESR1 mutations generate a transcriptionally reprogrammed phenotype promoting both metastasis and ET resistance in breast cancer. The rationale for this proposal is that identifying transcriptional changes in ESR1 metastases and resistant tumors, improves understanding of ESR1 mutant disease evolution. By targeting transcriptional changes occurring during this evolution, patients can remain on ET longer and extend metastasis-free survival. To test this central hypothesis, we propose two Specific Aims. Aim 1: What clonal and transcriptional changes accompany metastasis in ESR1 mutant-containing tumors subjected to ET pressure? This Aim uses computational methods to identify clonal evolution and transcriptional drivers of metastasis using single cell RNA/DNA-seq and ChIP-seq. Transcriptional drivers will be validated using FDA-approved inhibitors of these candidates in combination with ET using ex vivo assays. Aim 2: Does ET enhance the acquisition of ESR1 mutations, promoting subclonal evolution to drive therapy resistance? This Aim is addressed by developing models with ESR1 mutations acquired during long-term ET and utilizing computational biology via a combination of single cell DNA-seq and RNA-seq to determine the clonal evolution and transcriptional driver candidates of ET resistance. Driver candidates will be validated using selective inhibitors in combination with ET in vitro and in vivo. The results of this proposal will have a positive impact on the field as they lay the groundwork for mutant-specific therapeutic targets to slow the progression of disease by prolonging metastasis-free survival and ET sensitivity by enhancing the durability of treatment.