Mechanism-based strategies to target ER-mutant endocrine resistant breast cancer

项目摘要 三分之二的乳腺肿瘤表达雌激素受体（ERα），尽管许多最初对内分泌应答， 然而，在治疗中，大部分随后产生耐药性，由于晚期耐药细胞而导致死亡。 疾病包括我们在内的许多研究小组最近都记录了单核苷酸 ERα基因（ESR 1）突变在20-30%的内分泌抵抗转移性乳腺癌中的发生率。有限的临床 有证据表明，肿瘤获得ESR 1突变的患者生存期较短。 ESR 1热点突变聚集在配体结合结构域中。我们的CRISPR/Cas9基因组编辑的分析 具有最常见ESR 1突变（Y 537 S和D538 G）的乳腺癌细胞显示配体非依赖性， 转录活性和对选择性雌激素受体调节剂（SERM）的部分抗性， 降调节剂（SERD）。突变的ERα也显示了对不受雌激素经典调节的基因的调节， D538 G和Y 537 S之间存在显著差异。受突变型ERα独特调控的基因参与 在运动、迁移和粘附中，我们已经在ESR 1- 突变细胞我们假设ESR 1突变在内分泌抵抗性乳腺癌中富集， 由于突变型ERα的配体非依赖性活性，以及调节运动性和 粘连突变型ERα转录活性的改变是通过对ER α基因的重编程介导的。 ERα顺反子，由于与辅调节因子的相互作用改变。最后，我们假设SERD 将最有效地抑制突变ERα驱动的肿瘤生长。 为了解决这些假设，我们将使用多学科的方法，包括独特的体外和体内 突变型ERα作用模型和临床标本分析。具体目标是：（1）评估如何 不同的ESR 1突变改变了其转录活性和功能，2）表征配体依赖性 和突变体ER α的耐药活性，重点是功能活性的获得，以及3）确定是否 突变型ERα的独特转录调节存在于晚期内分泌抵抗性乳腺癌中， 以及它是否是进展和转移的关键。 我们希望我们对ERα突变的全面结构-功能研究不仅能为ER α突变的研究提供基础， 关于激素抵抗的信息，但将突出治疗靶向的新途径。!

Project Summary Two thirds of breast tumors express estrogen receptor (ERα), and although many initially respond to endocrine therapy, a large fraction subsequently develop resistance, causing death due to advanced hormone-resistant disease. A number of groups, including ours, have recently documented the occurrence of single nucleotide mutations in the ERα gene (ESR1) in 20-30% of endocrine-resistant metastatic breast cancer. Limited clinical evidence suggests that patients whose tumors have gained ESR1 mutations suffer from shorter survival. ESR1 hotspot mutations cluster in the ligand-binding domain. Analysis of our CRISPR/Cas9 genome edited breast cancer cells with the most common ESR1 mutations (Y537S and D538G) showed ligand-independent transcriptional activity, and partial resistance to selective estrogen receptor modulators (SERMs) and downregulators (SERDs). Mutant ERα also shows regulation of genes not classically regulated by estrogen, with significant differences between D538G and Y537S. Genes uniquely regulated by mutant ERα are involved in motility, migration, and adhesion, and we have identified such gain-of-function phenotypes in the ESR1- mutant cells. We hypothesize that mutations in ESR1 are enriched in endocrine-resistant breast cancer due to ligand-independent activity of mutant ERα, and a unique gain of function regulating motility and adhesion. The altered transcriptional activities of mutant ERα are mediated by reprograming of the ERα cistrome, as a result of altered interaction with coregulators. Finally, we hypothesize that SERDs will be most effective in inhibiting mutant ERα driven tumor growth. To address these hypotheses we will use a multidisciplinary approach including unique in vitro and in vivo models of mutant ERα action, and analysis of clinical specimens. The specific aims are 1) Evaluate how different ESR1 mutations alter its transcriptional activity and function, 2) Characterize the ligand-dependent and drug-resistant activities of mutant ERa, focusing on gain of function activities, and 3) Determine whether the unique transcriptional regulation by mutant ERα is present in advanced endocrine resistant breast cancers, and whether it is critical for progression and metastasis. We expect that our comprehensive structure-function studies of ERα mutations will not only provide basic information regarding hormone resistance, but will highlight novel routes to therapeutic targeting. !