Targeting the Brk-p27-cdk4 axis in cancer

靶向癌症中的 Brk-p27-cdk4 轴

• 批准号: 9297241
• 负责人: STACY W BLAIN
• 金额: $ 36.98万
• 依托单位: SUNY DOWNSTATE MEDICAL CENTER
• 依托单位国家: 美国
• 财政年份: 2016
• 资助国家: 美国
• 起止时间: 2016-07-01 至 2019-06-30
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/9297241
• 关键词: Alternative Splicing; Animal Model; Antineoplastic Agents; Archives; Benign; Binding; Biological; Biological Markers; Biological Models; Breast Cancer Cell; Breast Cancer Model; Breast Cancer cell line; Breast Epithelial Cells; Cell Aging; Cell Cycle Progression; Cell Cycle Regulation; Cell Line; Cell Proliferation; Cells; Chemicals; Clinical; Clinical Trials; Complex; Cyclin D1; Data; Disease; Drug resistance; Engineering; Exhibits; FDA approved; Generations; Genetic Models; Genotype; Goals; Human; In Vitro; Informed Consent; Injectable; Lipids; Malignant Neoplasms; Mammary Neoplasms; Mammary gland; Measures; Mediating; Modality; Modeling; Molecular; Molecular Analysis; Mono-S; Mus; Oncogenes; Oncogenic; Outcome; Pathology; Pathway interactions; Patients; Phosphorylation; Phosphotransferases; Physiological; Resistance; Role; SH3 Domains; Sampling; Source; Subgroup; Surrogate Markers; Testing; Therapeutic; Tissues; Tyrosine; Ubiquitin; University Hospitals; Variant; Xenograft Model; Xenograft procedure; base; cancer cell; in vivo; inhibitor/antagonist; insight; malignant breast neoplasm; nanoparticle; novel; overexpression; predicting response; predictive marker; prevent; response; senescence; tissue culture; tumor; tumor progression

This project will exploit a recently discovered oncogenic mechanism of cell cycle control exerted on cyclin D- cdk4 (DK4) by p27Kip1 and its activator, the Breast tumor Related Kinase (Brk), to target vulnerabilities in cancer cells. Although historically known as a DK4 assembly factor and cdk2 inhibitor, p27 also acts as a cdk4 ON/OFF “switch.” Tyrosine (Y) phosphorylation of p27 (pY88) gatekeeps both ATP binding and CAK phosphorylation of cdk4's T loop, essential for DK4 activation. We demonstrated that Brk is the physiological kinase that phosphorylates p27, and by doing so, increases cdk4 activity, cell cycle progression, and resistance to cdk4-specific inhibition by the chemical inhibitor Palbociclib, currently in clinical trials for breast cancer. Cyclin D and cdk4 are overexpressed in tumors, but their levels are not reliable biomarkers of oncogenic tumor potential because of the activating role p27 has on their complex. Our data predict that the Brk-p27-DK4 axis is important for transformation in DK4-dependent tumors and can explain tumor resistance to cdk4-specific inhibition. We determined that p27 interacts with Brk through a SH3:PxxP contact, specific for Brk's SH3 domain. The importance of this interaction is validated by characterization of a natural ALTernatively spliced Brk variant Brk (ALT), which contains only Brk's SH3 domain, and functions as a competitive inhibitor in vivo. Thus, blocking the Brk:p27 interaction is a viable strategy to inhibit cdk4 activity, which should be explored therapeutically. Our specific aims: 1) To examine pY as a marker of Palbociclib response in tissue culture and patient material. We will characterize cultured cell lines to statistically establish whether pY, as a measure of cdk4, correlates with Palbociclib sensitivity and could be used to predict response. In conjunction with our Dept. of Pathology, we will analyze archival breast cancer samples and primary patient material, including ER/PR+, Her- breast tumors, to correlate Palbociclib responsiveness and pY directly. 2) To demonstrate that ALT and pY blockage therapy can prevent proliferation in tissue culture models. Using breast cancer tissue culture models, we will show that ALT and Palbociclib-mediated arrest is different in terms of outcome and at the molecular and cell biological level. Our data will show that blocking pY using ALT is a powerful approach to block cancer cell proliferation, because it inhibits both cdk4 and cdk2, induces cellular senescence and prevents drug resistance. 3) To demonstrate that ALT and pY blockage therapy can prevent tumor progression in animal models. We will show that blocking p27 pY in mouse xenografts breast cancer models can prevent cancer progression and drug resistance.

该项目将利用最近发现的细胞周期调控的致癌机制对细胞周期蛋白D- cdk 4（DK 4）通过p27 Kip 1及其激活剂，乳腺肿瘤相关激酶（Brk），靶向 癌细胞虽然历史上被称为DK 4组装因子和cdk 2抑制剂，但p27也作为cdk 4组装因子和cdk 2抑制剂发挥作用。 开/关“开关”。p27（pY 88）门的酪氨酸（Y）磷酸化保持ATP结合和CAK CDK 4的T环的磷酸化，这是DK 4活化所必需的。我们证明了Brk是生理上 使p27磷酸化的激酶，并通过这样做增加CDK 4活性、细胞周期进程， 对化学抑制剂Palbociclib的cdk 4特异性抑制的耐药性，目前正在进行乳腺癌临床试验 癌细胞周期蛋白D和cdk 4在肿瘤中过表达，但它们的水平不是肿瘤的可靠生物标志物。 由于p27对它们的复合物具有激活作用，因此具有致癌肿瘤的潜力。我们的数据预测， Brk-p27-DK 4轴对于DK 4依赖性肿瘤的转化很重要，可以解释肿瘤抗性 CDK 4特异性抑制。我们确定p27通过SH 3：PxxP接触与Brk相互作用，特异于 Brk的SH 3结构域。这种相互作用的重要性是通过表征天然ALTernatively 剪接的Brk变体Brk（ALT），其仅包含Brk的SH 3结构域，并且作为竞争性抑制剂在 vivo.因此，阻断Brk：p27相互作用是抑制cdk 4活性的可行策略，这应该是有效的。 探索治疗。我们的具体目标：1）检查pY作为Palbociclib反应的标志物， 组织培养和患者材料。我们将对培养的细胞系进行表征，以统计学方式确定 pY作为cdk 4的指标，与Palbociclib敏感性相关，可用于预测疗效。在 与我们的部门合作我们将分析档案乳腺癌样本和主要患者 材料，包括ER/PR+、Her-乳腺肿瘤，以直接关联Palbociclib反应性和pY。2)到 证明ALT和pY阻断疗法可防止组织培养模型中的增殖。 使用乳腺癌组织培养模型，我们将证明ALT和Palbociclib介导的阻滞在以下方面是不同的： 在分子和细胞生物学水平上。我们的数据将表明，使用ALT阻断pY 是阻断癌细胞增殖的有效方法，因为它抑制CDK 4和CDK 2， 细胞衰老，防止耐药性。3)证明ALT和pY阻断治疗 可以防止动物模型中的肿瘤进展。我们将证明在小鼠异种移植物中阻断p27 pY 乳腺癌模型可以防止癌症进展和耐药性。