Therapeutic Targeting of Casein Kinase-1-delta in Primary and Metastatic Breast Cancer

我们的Multi-PI研究小组最近报道，酪蛋白激酶-1（CK1 δ）的δ亚型被扩增， 和/或在超过三分之一的乳腺癌中过表达，并且CK1 δ激活尤其表现在 难治性形式的乳腺癌，如缺乏靶向治疗的三阴性乳腺癌（TNBC）。 此外，我们建立了沉默CK1 δ，或抑制CK1 δ激酶活性与我们的纳摩尔效力， 高度选择性的CK1 δ和CK1 ε的小分子双重抑制剂，特异性地损害生长、存活 以及过表达CK1 δ的乳腺癌细胞的侵袭。值得注意的是，CK1 δ抑制也引起肿瘤 TNBC的消退，包括肺转移性TNBC和基底样PDX乳腺癌模型，并且没有 任何副作用最后，我们证明了CK1 δ抑制可抑制WNT/β-catenin信号传导， 经常激活但迄今为止无法治疗的途径，其在广泛的人类 恶性肿瘤重要的是，我们的新研究表明CK1 δ在TNBC转移中的作用， 显示CK1 δ信号传导是维持以下表达所必需的：（i）指导细胞增殖的转录因子， 上皮间质转化（EMT），包括Zeb1和Snail2;（ii）基质金属蛋白酶-1 （iii）控制TNBC细胞侵袭的基质金属蛋白酶1（MMP 1）、MMP 2和MMP 9;和（iii）乳腺癌干细胞（BCSC） Bmi 1和Sox 9控制自我更新。最后，我们已经证明我们的CK1 δ抑制剂具有协同作用， 选择用于治疗TNBC的临床DNA损伤化疗。总的来说，这些数据支持 假设CK1 δ是乳腺癌转移的驱动因素，靶向CK1 δ将阻断和 改善转移性三阴性乳腺癌治疗。因此，在Aim1中，我们将使用迭代 和严格的研究操作计划（ROP），以改善我们的双药的药代动力学（PK）特性 CK1 δ/CK1 ε抑制剂，并将开发和测试CK1 δ选择性抑制剂的疗效，以提供安全性 适合后续IND赋能研究的评估候选人。该ROP包括以下方面的协同作用测试： 我们的抑制剂与用于治疗TNBC的临床药物。此外，使用遗传方法和我们的CK1 δ 抑制剂，在目标2中，我们将测试CK1 δ在转移级联反应的每个步骤中的作用，包括内渗， 外渗、潜伏期和/或继发部位的建立。最后，在目标3中，使用磷酸化蛋白质组学， 基于活性的蛋白质组学分析和RNA-seq，我们将确定和测试下游效应子的作用， CK1 δ在控制TNBC转移中的作用，以及CK1 δ信号传导的EMT、MMPs和BCSC靶点。这些 研究，以及我们在TNBC中产生的对我们的CK1 δ/ε抑制剂耐药的研究，将定义急性 以及激酶组组分的慢性变化，这些变化可用于联合研究，以改善 治疗反应和阻断耐药性的出现。我们提出我们的研究计划将建立 CK1 δ是转移性三阴性乳腺癌的易感靶点，小分子CK1 δ/ε 或CK1 δ抑制剂将对乳腺肿瘤临床产生重大影响。

Our Multi-PI research team recently reported that the delta isoform of casein kinase-1 (CK1δ) is amplified and/or overexpressed in over a third of all breast cancers, and that CK1δ activation is especially manifest in refractory forms of breast cancer such as triple-negative breast cancer (TNBC) that lacks targeted therapies. Further, we established that silencing CK1δ, or inhibition of CK1δ kinase activity with our nanomolar potent, highly selective small molecule dual inhibitor of CK1δ and CK1ε, specifically compromises the growth, survival and invasion of breast cancer cells that overexpress CK1δ. Notably, CK1δ inhibition also provokes tumor regression of TNBC, including lung metastatic TNBC and basal-like PDX breast cancer models, and without any overt side effects. Finally, we demonstrated that CK1δ inhibition disables WNT/β-catenin signaling, a frequently activated yet heretofore undruggable pathway that is activated in a broad cast of human malignancies. Importantly, our new studies suggest roles for CK1δ in TNBC metastasis, where we have now shown that CK1δ signaling is necessary to sustain the expression of: (i) transcription factors that direct the epithelial to mesenchymal transition (EMT), including Zeb1 and Snail2; (ii) matrix metalloproteinases-1 (MMP1), MMP2 and MMP9 that control TNBC cell invasion; and (iii) the breast cancer stem cell (BCSC) factors Bmi1 and Sox9 that control self renewal. Finally, we have shown that our CK1δ inhibitors have synergy with select in-clinic DNA-damaging chemotherapies used to treat TNBC. Collectively, these data support the hypotheses that CK1δ is a driver of breast cancer metastases and that targeting CK1δ will block and improve treatment of metastatic triple negative breast cancer. Accordingly, in Aim1 we will use an iterative and rigorous research operating plan (ROP) to improve the pharmacokinetic (PK) properties of our dual CK1δ/CK1ε inhibitors, and will develop and test the efficacy of CK1δ-selective inhibitors, to deliver safety assessment candidates suitable for subsequent IND-enabling studies. This ROP includes tests of synergy of our inhibitors with in-clinic agents used to treat TNBC. Further, using genetic approaches and our CK1δ inhibitors, in Aim 2 we will test roles for CK1δ in each step of the metastatic cascade, including intravasation, extravasation, latency and/or establishment at the secondary site. Finally, in Aim 3, using phosphoproteomics, activity-based proteomic profiling, and RNA-seq we will identify and test the roles of downstream effectors of CK1δ in controlling TNBC metastasis, and the EMT, MMPs and BCSC targets of CK1δ signaling. These studies, and those in TNBC that we have generated that are resistant to our CK1δ/ε inhibitors, will define acute and chronic changes in components of the kinome that could be exploited for combination studies, to improve therapeutic response and block the emergence of resistance. We submit our research program will establish CK1δ as a vulnerability to target metastatic triple negative breast cancer, and that the small molecule CK1δ/ε or CK1δ inhibitors that we develop will have a major impact in the breast oncology clinic.