Pathway Specific Imaging in VHL Deficient Renal Cancer

描述（由申请人提供）：在美国，每年诊断出54,000例肾细胞癌（RCC）新病例，每年约有13,000例患者死于该疾病。最近，抗血管生成治疗取得了一定的进展，而化疗对这种肿瘤类型没有影响。因此，显然迫切需要新的替代方案。在这里，我们建议研究一种新的治疗肾癌的方法，这种方法也可能产生一种快速评估治疗反应的技术，从而有助于选择适当的治疗过程。发酵性糖酵解在许多实体肿瘤中很常见，但在大多数RCC中由Von-Hippel Lindau （VHL）缺陷肿瘤突变引起的肾癌亚群中起关键作用（因为它导致缺氧诱导因子（HIF）稳定）。我们建议研究寻求逆转Warburg效应的肾癌治疗方法。这可以通过激活PDH（丙酮酸脱氢酶）的线粒体再激活来实现，这有助于丙酮酸进入三羧酸循环（TCA）。PDH酶可以被一种小分子抑制剂，二氯乙酸（DCA）激活，该抑制剂阻断丙酮酸脱氢酶激酶（PDK），进而负向调节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生存。该建议的关键特点是将丙酮酸的命运重新定向到克雷布斯循环中，因此肿瘤细胞将优先受到伤害。然而，到目前为止，还没有一种体内方法来确定DCA或其他重定向丙酮酸归宿的方法是否在体内实现了它们的目标。超极化磁共振成像是一种新兴技术，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评估RCC肿瘤对旨在逆转Warburg效应的治疗反应的工具。我们的主要工作假设是，在肾细胞癌的原位小鼠模型中，给药DCA会导致乳酸生成减少，并且这种“药效学”测量将与该模型中肿瘤负荷的减少相关。使用不同剂量和时间表的DCA给药，我们将使用超极化碳-13标记丙酮酸收集非侵入性成像数据。因此，我们的具体目的如下：目的1：将非侵入性成像数据与各种DCA剂量相关联（“试点研究”）。目的2：在该模型中，将慢性DCA治疗后丙酮酸代谢的影像学测量与肿瘤负荷、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. PUBLIC HEALTH RELEVANCE: Fermentative glycolysis (conversion of pyruvate to lactate) is common to many solid tumors but has a key role in renal cancers resulting from mutations in Von-Hippel Lindau (VHL). Studies have demonstrated that in VHL-deficient clear cell renal carcinoma, hypoxia inducible factor (HIF-1) mediates increased glucose uptake, increased lactate production, and decreased respiration. In this proposal we bring together a team of radiologists, physicists, pathologists, and cancer scientists to help accomplish this goal using a state of the art technology known as hyperpolarizing MRI. In particular, we present pre-clinical data showing that this approach is indeed feasible and that we have a validated preclinical renal cancer animal model available to us. We propose to test whether the in vivo administration of dichloroacetate (DCA) results in decreased formation of lactate from pyruvate in this animal model and whether this flux measurement correlates with decreased tumor burden. The importance of these studies is that it will allow for efficient translation into the clinic of drugs that affect the fate of pyruvate, a whole new approach to cancer therapeutics.