Therapeutically targeting cancer cell motility

 描述（由申请人提供）： 前列腺癌（PCa）的死亡率是由转移的形成引起的。这对美国退伍军人来说是个大问题。因此，驱动转移发展的过程，如细胞运动性增加，代表了高价值的治疗靶点。所有选择性治疗靶细胞运动和随之发生的转移的尝试都失败了。我们通过设计一种独特的策略来解决这个棘手而重要的问题，该策略使用小化学品作为高度精细的探针来识别新的和重要的生物调控位点。这使我们合成了抑制HSP 90 β上Ser 226磷酸化的探针KBU 2046。Ser 226的磷酸化驱动细胞侵袭并介导KBU 2046抗侵袭功效。当口服给药时，KBU 2046在nM浓度下抑制小鼠中的人PCa转移。已知HSP 90分子伴侣作用维持雄激素受体（AR）处于其功能状态，我们继续证明KBU 2046介导的HSP 90功能破坏抑制AR信号传导和AR驱动的细胞生长。最后，全面的临床前毒性和药理学研究都支持KBU 2046作为一种药物，将具有很高的人体活性潜力。我们假设我们的化学探针策略已经确定HSP 90 β Ser 226磷酸化的调节是调节转移进展的一种新的选择性机制，KBU 2046的疗效至少部分是由于调节客户蛋白与HSP 90 β的结合，导致Ser 226磷酸化状态的变化，并且该策略提供了抑制人类PCa转移的可行途径。目标1.表征KBU 2046影响客户蛋白结合和Ser 226磷酸化的分子机制。KBU 2046不直接抑制激酶功能。它改变了客户蛋白与HSP 90 β的结合，似乎是通过稳定HSP 90 β/CDC 37异源复合物来实现的。研究将充分表征KBU 2046诱导的客户蛋白与HSP 90 β结合的变化，并将继续评估它们如何影响Ser 226磷酸化状态和细胞运动性。目标2.评价KBU 2046在临床相关的人PCa鼠异种移植模型中的功效。目的2A检查KBU 2046是否增强激素治疗的功效，并延迟对它的抗性的出现。目的2B中的实验建立在我们最近发现KBU 2046选择性地抑制骨粘连蛋白表达的基础上。骨连接素是一种细胞外基质蛋白，已显示其驱动人PCa的转移。我们假设KBU 2046将破坏PCa细胞向骨的传播，并将使用转移的心内注射模型来测试这一点。冲击研究将增加我们对癌细胞运动和转移的基本生物学的理解，并将告知我们在人类中调节它的最佳方法。

 DESCRIPTION (provided by applicant): Prostate cancer (PCa) mortality is caused by the formation of metastases. This is a major problem for US veterans. Processes that drive the development of metastases, such as increased cell motility, therefore represent high value therapeutic targets. All attempts to selectively therapeutically target cell motility and consequent metastasis have failed. We approached this intractable and important problem by designing a unique strategy that used small chemicals as highly refined probes to identify novel and important biological regulatory sites. This led us to synthesize the probe, KBU2046, which inhibits phosphorylation of Ser226 on HSP90β. Phosphorylation of Ser226 drives cell invasion and mediates KBU2046 anti-invasion efficacy. When administered orally, KBU2046 inhibits human PCa metastasis in mice at nM concentrations. Knowing that HSP90 chaperone action maintains androgen receptor (AR) in its functional state, we went on to demonstrate that KBU2046-mediated disruption of HSP90 function inhibits AR signaling and AR-driven cell growth. Finally, comprehensive preclinical toxicity and pharmacology studies all support that KBU2046, as a drug, will have a high potential for activity in humans. We hypothesize that our chemical probe strategy has identified modulation of HSP90β Ser226 phosphorylation as a novel and selective mechanism regulating metastatic progression, that KBU2046 efficacy is due, at least in part, to modulation of client protein binding to HSP90β, resulting in changes in Ser226 phosphorylation status, and that this strategy provides a viable pathway for inhibiting PCa metastasis in humans. Aim 1. Characterize the molecular mechanism by which KBU2046 affects client protein binding and Ser226 phosphorylation. KBU2046 does not directly inhibit kinase function. It alters binding of client proteins to HSP90β, and appears to do so through stabilization of the HSP90β/CDC37 heterocomplex. Studies will fully characterize KBU2046 induced changes in client protein binding to HSP90β, and will go on to assess how they affect Ser226 phosphorylation status and cell motility. Aim 2. Evaluate KBU2046 efficacy in clinically relevant human PCa murine xenograft models. Aim 2A examines whether KBU2046 enhances the efficacy of hormone therapy, and delays emergence of resistance to it. Experiments in Aim 2B build upon our recent finding that KBU2046 selectively suppresses osteonectin expression. Osteonectin is an extracellular matrix protein, which has been shown to drive metastasis in human PCa. We hypothesize that KBU2046 will disrupt PCa cell dissemination to bone, and will test this using an intra-cardiac injection model of metastasis. Impact. Studies will increase our understanding of the basic biology of cancer cell motility and metastasis, and will inform us of the optimal means to modulate it in humans.