Posttranslational Regulation of FOXA1 in Breast Cancer

FOXA1 在乳腺癌中的翻译后调控

• 批准号: 10978823
• 负责人: Hector Luis Franco
• 金额: $ 30.6万
• 依托单位: COMPREHENSIVE CANCER CENTER/ UNIV/PR
• 依托单位国家: 美国
• 财政年份: 2023
• 资助国家: 美国
• 起止时间: 2023-09-01 至 2027-12-31
• 项目状态: 未结题
• 来源: https://reporter.nih.gov/project-details/10978823
• 关键词: Posttranslational; Regulation; FOXA1; Breast; Cancer

Project Summary Breast cancer is the second leading cause of cancer mortality in women and nearly 75% of all breast tumors express estrogen receptor alpha (ER) at the time of diagnosis. Despite the therapeutic successes of endocrine therapies designed to target ER function, about 30-40% of tumors become resistant to endocrine therapy, either through de novo or acquired resistance, and still retain the expression of ER. Herein we propose to study the regulation of FOXA1, a pioneer transcription factor that enables ER binding to chromatin, whose theoretical inhibition would circumvent known mechanisms of endocrine therapy resistance. In breast cancer, FOXA1 is responsible for almost all of the ER binding events in the genome and its upregulation is associated with enhancer reprograming in endocrine resistance. However, there is a paucity of information about how FOXA1 itself is regulated and how cancer cells repurpose its pioneering activities to drive oncogenesis. To this end, our lab has been studying the crosstalk between the endocrine and immune systems in breast cancer. We have discovered that FOXA1, in response to the proinflammatory cytokines, is driven to non- canonical sites across the genome to promote chromatin accessibility for estrogen-liganded ER. These newly formed enhancers were found in compacted/latent regions of the genome and promoted the expression of a novel gene set that was predictive of poor clinical outcomes in patients. Concurrently, we discovered that FOXA1 is post-translationally modified (PTM) in response to proinflammatory cytokines at two evolutionarily conserved amino acids. The post-translational modification of FOXA1 in response to external stimuli has not been shown before and suggests an important mechanism that underlies FOXA1 regulation and function. Therefore, the overall goal of this project is to determine the molecular events that allow proinflammatory signaling to alter endocrine signaling through modulation of FOXA1 function and the biological consequences of this crosstalk. We hypothesize that estrogen- and TNFα-directed PTMs of FOXA1 dictate binding site selection, driving ERα to non-canonical enhancers across the genome, leading to expression programs that underlie the tumorigenesis of breast cancer. To systematically test this hypothesis, will use an integrated set of molecular, genomic, and proteomic approaches to: (Aim 1) define the role of FOXA1 PTMs on its pioneering function and chromatin occupancy, (Aim 2) identify the writers and readers of FOXA1 PTMs, and (Aim 3) understand inflammation- based modulation of FOXA1 independent of PTMs. We will perform these experiments in breast cancer cell lines, ER+ patient-derived xenografts (PDX), and in ER+ mature luminal cells isolated from patient tumors. The dependence on FOXA1 for hormone receptor signaling makes it an attractive therapeutic target. While there are currently no known inhibitors of FOXA1 and its protein structure makes it difficult to target therapeutically, our ability to understand basic molecular mechanisms is directly correlated with our ability to develop better therapeutic interventions. Defining how FOXA1 is regulated becomes key to this endeavor.

项目摘要 乳腺癌是女性癌症死亡率的第二大原因，占所有乳腺癌死亡率的近75%。 肿瘤在诊断时表达雌激素受体α（ER）。尽管治疗成功， 针对ER功能的内分泌治疗，约30-40%的肿瘤对内分泌治疗产生耐药性。 治疗，无论是通过从头或获得性耐药，仍然保留ER的表达。在此，我们建议 研究FOXA 1的调节，FOXA 1是一种使ER与染色质结合的先驱转录因子， 理论上的抑制将避开已知的内分泌治疗抗性机制。在乳腺癌中， FOXA 1负责基因组中几乎所有的ER结合事件，并且其上调与 内分泌抵抗的增强重编程。然而，关于如何做到这一点的信息很少。 FOXA 1本身受到调节，癌细胞如何重新利用其开拓活动来驱动肿瘤发生。 为此，我们的实验室一直在研究内分泌和免疫系统之间的串扰， 乳腺癌我们已经发现FOXA 1在对促炎细胞因子的反应中，被驱动到非炎症细胞因子。 基因组中的典型位点，以促进雌激素配体ER的染色质可及性。这些新 在基因组的致密/潜在区域发现了形成的增强子，并促进了a的表达。 新的基因集，可预测患者的不良临床结果。同时，我们发现FOXA 1 在两个进化上保守的位置， 个氨基酸FOXA 1对外界刺激的翻译后修饰尚未显示 这表明了FOXA 1调节和功能的重要机制。因此 这个项目的总体目标是确定允许促炎信号改变的分子事件 内分泌信号通过FOXA 1功能的调节和这种串扰的生物学后果。 我们假设FOXA 1的雌激素和TNFα导向的PTM决定结合位点的选择，驱动ERα 基因组中的非典型增强子，导致肿瘤发生的基础表达程序 乳腺癌为了系统地检验这一假设，将使用一套完整的分子、基因组和 蛋白质组学方法：（目的1）确定FOXA 1 PTM在其先锋功能和染色质中的作用 占据，（目的2）识别FOXA 1 PTM的作者和读者，（目的3）了解炎症- 基于FOXA 1独立于PTM的调节。我们将在乳腺癌细胞中进行这些实验 细胞系、ER+患者来源的异种移植物（PDX）和从患者肿瘤分离的ER+成熟管腔细胞中。的 激素受体信号传导对FOXA 1的依赖性使其成为有吸引力的治疗靶点。虽然有 我们的研究表明，目前还没有已知的FOXA 1抑制剂，其蛋白质结构使得治疗靶向变得困难。 理解基本分子机制的能力与我们更好地发展的能力直接相关。 治疗干预。定义FOXA 1如何调节成为这一奋进的关键。

项目成果

Single-Cell Transcriptional and Epigenetic Profiles of Male Breast Cancer Nominate Salient Cancer-Specific Enhancers.

男性乳腺癌的单细胞转录和表观遗传学特征提名了明显的癌症特异性增强子。

• DOI: 10.3390/ijms241713053
• 发表时间: 2023-08-22
• 期刊: INTERNATIONAL JOURNAL OF MOLECULAR SCIENCES
• 影响因子: 5.6
• 作者: Kim, Hyunsoo;Wisniewska, Kamila;Regner, Matthew J.;Thennavan, Aatish;Spanheimer, Philip M.;Franco, Hector L.
• 通讯作者: Franco, Hector L.