Pathway Specific Imaging in VHL Deficient Renal Cancer

描述（由申请人提供）：美国每年诊断出54，000例新的肾细胞癌（RCC）病例，每年约有13，000例患者死于该疾病。最近，抗血管生成治疗已经产生了适度的收益，而化疗对这种肿瘤类型没有影响。因此，很明显，迫切需要新的替代方案。在这里，我们建议研究一种新的肾癌治疗方法，也可能产生一种技术，以快速评估治疗反应，从而帮助选择一个适当的疗程。发酵性糖酵解在许多实体瘤中是常见的，但在由Von-Hippel Lindau（VHL）缺陷型肿瘤中的突变引起的肾癌亚组中具有关键作用，其发生在大多数RCC中（因为其导致缺氧诱导因子（HIF）稳定）。我们建议研究寻求逆转瓦尔堡效应的肾癌疗法。这可以通过线粒体在激活PDH（丙酮酸脱氢酶）中的再激活来实现，PDH促进丙酮酸进入三羧酸循环（TCA）。PDH酶可被小分子抑制剂二氯乙酸盐（DCA）激活，后者阻断丙酮酸脱氢酶激酶（PDK），进而负调节PDH。因此，影响丙酮酸代谢命运的分子途径可能反过来影响肿瘤存活。该建议的关键特征是将丙酮酸的命运重新定向到克雷布斯循环中，从而使肿瘤细胞优先受到伤害。然而，迄今为止，还没有体内方法来确定DCA或其他改变丙酮酸命运的方法是否实际上在体内实现了它们的目标。超极化磁共振成像是一种新兴的技术，可以提供这样的生物相关。在这里，我们建议使用超极化丙酮酸作为一种工具，用于评估反应RCC肿瘤的治疗，旨在扭转瓦尔堡效应。我们的主要工作假设是DCA给药将导致肾细胞癌原位小鼠模型中乳酸盐形成减少，并且这种“药效学”测量将与该模型中肿瘤负荷降低相关。使用各种剂量和时间表的DCA管理，我们将收集非侵入性成像数据使用超极化碳-13标记的丙酮酸。因此，我们的具体目标如下：目标1：将非侵入性成像数据与各种DCA剂量相关联（“试点研究”）。目标二：将慢性DCA治疗后丙酮酸代谢的这些成像测量与该模型中的肿瘤负荷、肿瘤增殖和凋亡指数以及PDH磷酸化状态相关联（“纵向研究”）。这些研究的重要性在于，它们将使影响丙酮酸命运的药物有效地转化为临床，这可能为癌症治疗提供一种全新的方法。

DESCRIPTION (provided by applicant): 54,000 new cases of renal cell cancer (RCC) are diagnosed each year in the US and approximately 13,000 patients succumb to the disease annually. Recently, anti-angiogenic therapy has produced modest gains, whereas chemotherapy has had no impact in this tumor type. It is therefore clear that novel alternatives are sorely needed. Here we propose to study a novel therapeutic approach to renal cancer that may also yield a technique to rapidly assess treatment response and hence aid in the selection of an appropriate course of treatment. Fermentative glycolysis is common to many solid tumors but has a key role in a subset of renal cancers resulting from mutations in Von-Hippel Lindau (VHL) deficient tumors which occurs in the majority of RCC (as it leads to hypoxia inducible factor (HIF) stabilization). We propose to study renal cancer therapies that seek to reverse the Warburg effect. This can be accomplished through reactivation of the mitochondria in activating PDH (pyruvate dehydrogenase), which facilitates pyruvate entry into tricarboxylic acid cycle (TCA). The enzyme PDH can be activated by a small molecule inhibitor, dichloroacetate (DCA) that blocks pyruvate dehydrogenase kinase (PDK), which in turn negatively regulates PDH. Hence molecular pathways influencing pyruvate's metabolic fate may, in turn, impact tumor survival. The key feature of this proposal is to redirect the fate of pyruvate into the Krebs cycle, so that tumor cells will be preferentially harmed. To date, however, there has been no in vivo methodology to determine whether DCA or other methods of redirecting the fate of pyruvate are in fact accomplishing their goal in vivo. Hyperpolarized magnetic resonance imaging is an emerging technology that may provide such a biocorrelate. Here we propose to use hyperpolarized pyruvate as a tool for assessing the response RCC tumors to therapies that aim to reverse the Warburg effect. Our major working hypothesis is that administration of DCA will result in decreased lactate formation in an orthotopic mouse model of renal cell carcinoma, and that this "pharmacodynamic" measurement will correlate with decreased tumor burden in this model. Using a variety of doses and schedules for DCA administration, we will collect non-invasive imaging data using hyperpolarized carbon-13 labeled pyruvate. Hence our specific aims are as follows; Aim 1: To correlate non-invasive imaging data with various DCA doses ("the pilot study"). Aim 2: To correlate these imaging measurements of pyruvate metabolism after chronic DCA treatment with tumor burden, tumor proliferation and apoptotic indices, and PDH phosphorylation status in this model ("the longitudinal study"). The importance of these studies is that they will allow for efficient translation into the clinic of drugs that affect the fate of pyruvate, which may provide a whole new approach to cancer therapeutics.