Role of Phospho-Progesterone Receptors (PR) in Hormone Refractory Breast Cancer

磷酸孕酮受体 (PR) 在激素难治性乳腺癌中的作用

• 批准号: 8234766
• 负责人: Carol A Lange
• 金额: $ 36.67万
• 依托单位: UNIVERSITY OF MINNESOTA
• 依托单位国家: 美国
• 财政年份: 2012
• 资助国家: 美国
• 起止时间: 2012-02-28 至 2016-12-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/8234766
• 关键词: Androgen Receptor; Anti-Progestin; Antibodies; Aromatase Inhibitors; Behavior; Binding; Biological Assay; Biological Models; Breast Cancer Cell; CDK2 gene; Cancer Biology; Cancer cell line; Cell Line; Cell Proliferation; Cell model; Clinical; Data; Development; Endocrine; Engineering; Estrogen Antagonists; Estrogen Receptor alpha; Estrogen Receptors; Estrogen Therapy; Estrogen receptor positive; Estrogens; Event; Exhibits; Funding; Gene Expression Regulation; Gene Targeting; Genes; Glucocorticoids; Goals; Growth; Growth Factor; Hormones; Human; Hyperactive behavior; Hyperplasia; In Vitro; Lesion; Ligands; Mammary Neoplasms; Mediating; Mediator of activation protein; Membrane; Messenger RNA; Modeling; Modification; Molecular; NCOA3 gene; Pathway interactions; Patients; Peptides; Phenotype; Phosphorylation; Phosphotransferases; Play; Post-Translational Protein Processing; Progesterone; Progesterone Receptors; Progestins; Protein Kinase; Proteins; Receptor Cross-Talk; Receptor Gene; Receptor Protein-Tyrosine Kinases; Receptor Signaling; Refractory; Regulation; Research; Resistance; Role; SRC gene; Signal Pathway; Signal Transduction; Steroid Receptors; Tamoxifen; Testing; Therapeutic Intervention; Transgenic Mice; Transplantation; Ubiquitin; Validation; base; cross reactivity; hormone regulation; hormone resistance; hormone therapy; in vitro Model; in vivo; in vivo Model; innovation; insight; malignant breast neoplasm; multicatalytic endopeptidase complex; mutant; neoplastic; next generation; novel; promoter; receptor; receptor expression; receptor function; response; steroid hormone; steroid hormone receptor; therapeutic target; tumor; tumor growth; tumor progression

DESCRIPTION (provided by applicant): The mechanism(s) of breast cancer progression to steroid receptor (SR)-positive but hormone refractory breast cancer remain elusive. Much of the research in this field is focused on the linkage of estrogen receptor-? (ER) to signal transduction, as mediated by peptide growth factor activation of tyrosine kinase receptors; these molecules are important clinical targets. However, progesterone receptors (PR) may also play a key role as mediators of early breast cancer progression. Recently, we uncovered a novel mechanism of hormone-independent hyperactivation of PR transcriptional activity that is mediated by membrane-initiated phosphorylation events. In response to mitogenic protein kinases (c-Src, MAPKs, CDK2) often elevated in breast cancer, persistent phosphorylation of PR Ser294 blocks ligand-induced sumoylation at K388 (a repressive modification). Abundant total PR is a marker of "good tumor" behavior. However, we hypothesize that de-repressed phospho-PR acts on genes whose products mediate early breast cancer progression or "bad tumor" behavior. One check on PR hyperactivity includes rapid ligand-dependent degradation by the ubiquitin-proteasome pathway. Indeed, in the presence of hormone, phospho-PR undergoes rapid turnover, often rendering the low abundance protein undetectable by standard antibody-binding assays (i.e. clinically used IHC). Clinical observations of PR "loss" have led to the incorrect conclusion that PR transcriptional activity is unimportant in "PR-low" breast cancers. However, our studies reveal that phospho-PR is transcriptionally hyperactive and remarkably, targets genes that are not sensitive to progesterone or progestins; IRS-1 is an example of a ligand-independent phospho-PR gene. Furthermore, under conditions of high kinase activities, Ser294-phosphorylated PRs are not sumoylated, and thus fail to transrepress ER but may instead cooperate with ER at non-classical (non-PRE containing) gene targets in the complete absence of steroid hormones; STC-1 is an example of an ER-gene that is de-repressed by phospho-PR. Notably, the proliferation of breast cancer cell models expressing mutant PRs that cannot be sumoylated (K388R) is very sensitive to estrogen, but resistant to anti-estrogen. Similarly, we predict that phospho-PR signaling drives the growth of some hormone-refractory breast cancers that can be identified by a unique PR gene signature. Herein, we will define the phospho-PR gene signature using unique cell line models engineered for inducible PR expression. The role of the PR sumoylation/phosphorylation "switch" in the regulation of hormone responsiveness at endogenous genes will be defined (Mechanisms; Aim 1). Our unique phospho-PR gene signature will be validated in in vitro models of tam- and AI- (aromatase inhibitor) resistance and in human tumors (Validation; Aim 2). Finally, our innovative hypothesis will be tested in AIB1-transgenic mice, an in vivo model of SR-driven (ER+/PR+) and tam-resistant breast cancer (Biology; Aim 3). Little is known about how PR and ER/PR interactions contribute to hormone resistance in breast tumors. Our studies on phospho- PR signaling will provide valuable insight into the coordinated regulation of PR and ER function by pathways that can be easily targeted for therapeutic intervention. PUBLIC HEALTH RELEVANCE: These studies are focused on progesterone receptor (PR) action as it relates to mechanisms of hormone refractory breast cancer progression and therapeutic targeting. Our goal is to show that growth factors de-repress PR and thereby alter PR function and interaction with ER at endogenous genes important for breast cancer cell proliferation, survival, and early progression to endocrine resistance. A unique phospho-PR gene signature will be defined in breast cancer cell lines engineered to express versions of PR representing known post-translational modifications, validated in well-characterized independent models of tamoxifen or aromatase inhibitor-resistant breast cancer (expressing endogenous wt PR), and extended into both in vitro and in vivo translational models of steroid receptor-positive endocrine-resistance.

描述（由申请人提供）：乳腺癌进展为类固醇受体（SR）阳性但激素难治性乳腺癌的机制仍然难以捉摸。这一领域的研究主要集中在雌激素受体-？(ER)信号转导，如由肽生长因子激活酪氨酸激酶受体介导的;这些分子是重要的临床靶点。然而，孕激素受体（PR）也可能作为早期乳腺癌进展的介质发挥关键作用。最近，我们发现了一种新的机制，非依赖于细胞膜启动的磷酸化事件介导的PR转录活性的过度激活。在响应促有丝分裂蛋白激酶（c-Src，MAPKs，CDK 2）往往在乳腺癌中升高，PR Ser 294的持续磷酸化阻断配体诱导的K388（抑制性修饰）SUMO化。充足的总PR是“良好肿瘤”行为的标志。然而，我们假设去抑制的磷酸化PR作用于其产物介导早期乳腺癌进展或“不良肿瘤”行为的基因。对PR过度活跃的一种检查包括通过泛素-蛋白酶体途径的快速配体依赖性降解。事实上，在激素的存在下，磷酸-PR经历快速周转，通常使得低丰度蛋白无法通过标准抗体结合测定（即临床使用的IHC）检测到。PR“损失”的临床观察导致了错误的结论，即PR转录活性在“PR低”乳腺癌中不重要。然而，我们的研究表明，磷酸-PR是转录过度活跃，并显着，目标基因是不敏感的孕酮或孕激素; IRS-1是一个配体独立的磷酸-PR基因的一个例子。此外，在高激酶活性的条件下，Ser 294-磷酸化的PR不被SUMO化，因此不能反式抑制ER，而是可以在非经典的条件下与ER合作。在完全不存在类固醇激素的情况下的（不含PRE的）基因靶标; STC-1是被磷酸-PR去阻遏的ER基因的一个实例。表达不能被类小泛素化的突变PR（K388 R）的乳腺癌细胞模型的增殖对雌激素非常敏感，但对抗雌激素具有抗性。同样，我们预测磷酸化PR信号驱动一些乳腺癌的生长，这些乳腺癌可以通过独特的PR基因特征来识别。在此，我们将使用针对诱导型PR表达而工程化的独特细胞系模型来定义磷酸化PR基因签名。将定义PR类小泛素化/磷酸化“开关”在内源性基因的激素反应性调节中的作用（机制;目的1）。我们独特的磷酸化PR基因特征将在tam和AI（芳香酶抑制剂）抗性的体外模型和人类肿瘤中得到验证（验证;目标2）。最后，我们的创新假设将在AIB 1转基因小鼠中进行测试，这是一种SR驱动（ER+/PR+）和tam耐药乳腺癌的体内模型（生物学;目标3）。关于PR和ER/PR相互作用如何促进乳腺肿瘤中的激素抵抗知之甚少。我们对磷酸化PR信号传导的研究将为PR和ER功能的协调调节提供有价值的见解，这些途径可以很容易地用于治疗干预。 公共卫生相关性：这些研究的重点是孕激素受体（PR）的作用，因为它涉及激素难治性乳腺癌进展和治疗靶向的机制。我们的目标是表明生长因子去抑制PR，从而改变PR功能和与ER在内源性基因的相互作用，这些基因对乳腺癌细胞增殖、存活和内分泌抵抗的早期进展很重要。将在乳腺癌细胞系中定义独特的磷酸-PR基因标签，所述乳腺癌细胞系被工程化以表达代表已知翻译后修饰的PR形式，在他莫昔芬或芳香化酶受体抗性乳腺癌（表达内源性wt PR）的充分表征的独立模型中验证，并扩展到类固醇受体阳性内分泌抗性的体外和体内翻译模型中。