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: 8623286
• 负责人: Carol A Lange
• 金额: $ 5万
• 依托单位: UNIVERSITY OF MINNESOTA
• 依托单位国家: 美国
• 财政年份: 2013
• 资助国家: 美国
• 起止时间: 2013-06-01 至 2015-05-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/8623286
• 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

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.

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(S)仍不清楚。这一领域的大部分研究都集中在雌激素受体-？(Er)通过多肽生长因子激活酪氨酸激酶受体介导的信号转导；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媒介发挥关键作用。最近，我们发现了一种新的机制，即由膜启动的磷酸化事件介导的激素非依赖性PR转录活性的过度激活。作为对乳腺癌中常见的促有丝分裂蛋白激酶(c-Src、MAPKs、CDK2)的反应，PR Ser294的持续磷酸化阻断了K388处配体诱导的SUMO化(一种抑制性修饰)。血清总PR水平的升高是“良性肿瘤”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。PR过度活动的一种检查包括泛素-蛋白酶体途径的快速配体依赖降解。事实上，在激素存在的情况下，磷酸化PR经历了快速的周转，经常使低丰度的蛋白质无法通过标准的抗体结合分析(即临床使用的IHC)检测到。对PR“缺失”的临床观察导致了一个错误的结论，即PR转录活性在PR“低”的乳腺癌中并不重要。然而，我们的研究表明，磷酸化PR在转录上高度活跃，并且显著地针对对孕酮或孕激素不敏感的基因；IRS-1是一个配体无关的磷酸化PR基因的例子。此外，在高激酶活性的条件下，Ser294-磷酸化的PR不是总和基化的，因此不能转录抑制ER，而是在完全没有类固醇激素的情况下在非经典(不含前)的基因靶点与ER协同作用；STC-1是一个被磷酸化的PR去抑制的ER基因的例子。值得注意的是，表达不能相加的突变PR(K388R)的乳腺癌细胞模型的增殖对雌激素非常敏感，但对抗雌激素具有耐药性。同样，我们预测，磷酸化PR信号驱动一些激素抵抗型乳腺癌的生长，这些乳腺癌可以通过独特的PR基因签名来识别。在这里，我们将使用为诱导PR表达而设计的独特的细胞系模型来定义磷酸化PR基因签名。PR总和/磷酸化“开关”在调节内源性基因的激素反应性中的作用将被定义(机制；目标1)。我们独特的磷酸化PR基因签名将在和AI(芳香酶抑制剂)耐药的体外模型以及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AIB1转基因小鼠身上进行测试，这是一种SR驱动(ER+/PR+)和耐药乳腺癌的体内模型(生物学；目标3)。关于PR和ER/PR的相互作用如何导致乳腺肿瘤的激素抵抗，人们知之甚少。我们对磷酸化PR信号的研究将对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作为治疗干预的靶点。