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: 8785100
• 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 2015-12-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/8785100
• 关键词: Androgen Receptor; Anti-Progestin; Antibodies; Aromatase Inhibitors; Behavior; Binding; Biological Assay; Biological Models; Breast Cancer Cell; Breast Cancer cell line; CDK2 gene; Cancer Biology; 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.

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。该领域的大部分研究都集中在雌激素受体-？ (ER) 信号转导，由肽生长因子激活酪氨酸激酶受体介导；这些分子是重要的临床靶点。然而，黄体酮受体（PR）也可能作为早期乳腺癌进展的介质发挥关键作用。最近，我们发现了一种不依赖激素的 PR 转录活性过度激活的新机制，该机制是由膜启动的磷酸化事件介导的。为了响应乳腺癌中经常升高的促有丝分裂蛋白激酶（c-Src、MAPK、CDK2），PR Ser294 的持续磷酸化会阻断配体诱导的 K388 处的 sumoylation（抑制性修饰）。丰富的总 PR 是“良好肿瘤”行为的标志。然而，我们假设去抑制的磷酸-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 过度活跃的一项检查包括泛素-蛋白酶体途径的快速配体依赖性降解。事实上，在激素存在的情况下，磷酸化 PR 会发生快速周转，通常导致标准抗体结合测定（即临床使用的 IHC）无法检测到低丰度蛋白质。 PR“丢失”的临床观察得出了错误的结论，即 PR 转录活性在“PR 低”乳腺癌中并不重要。然而，我们的研究表明，磷酸化 PR 转录过度活跃，并且明显地针对对孕酮或孕激素不敏感的基因； IRS-1 是配体独立的磷酸-PR 基因的一个例子。此外，在高激酶活性的条件下，Ser294 磷酸化的 PR 不会被苏酰化，因此无法反式抑制 ER，但在完全不存在类固醇激素的情况下，可能会在非经典（不含 PRE 的）基因靶点上与 ER 合作； STC-1 是被磷酸-PR 去抑制的 ER 基因的一个例子。值得注意的是，表达不能被苏酰化的突变PR（K388R）的乳腺癌细胞模型的增殖对雌激素非常敏感，但对抗雌激素有抵抗力。同样，我们预测磷酸化 PR 信号传导会驱动一些激素难治性乳腺癌的生长，这些乳腺癌可以通过独特的 PR 基因特征来识别。在此，我们将使用专为诱导型 PR 表达而设计的独特细胞系模型来定义磷酸化 PR 基因特征。 PR 苏酰化/磷酸化“开关”在内源基因激素反应性调节中的作用将被定义（机制；目标 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）耐药性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 转基因小鼠中进行测试，这是 SR 驱动的 (ER+/​​PR+) 和 tam 耐药性乳腺癌的体内模型（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 信号传导的研究将为通过可轻松靶向治疗干预的途径协调调节 PR 和 ER 功能提供有价值的见解。