Functional Investigation of the Mitochondrial Pyruvate Carrier in Prostate Cancer

 描述(申请人提供)：雄激素受体(AR)诱导的从头合成脂质使激素敏感和去势抵抗的前列腺癌细胞生长和存活，但AR介导的支持前列腺癌脂肪生成的代谢变化尚不清楚。脂肪生成需要丙酮酸来产生脂质前体(例如柠檬酸盐)，最近的体内成像策略已经证明，与几乎所有 在其他肿瘤中，前列腺癌比葡萄糖更快、更可靠地吸收丙酮酸。此外，线粒体丙酮酸载体(MPC)的一个亚基MPC2是一个直接的AR靶基因，这表明AR的丙酮酸转运和脂肪生成之间存在联系。该项目的长期目标是确定、表征和有针对性地干扰前列腺癌代谢的关键介质。目前这项提案的总体目标是确定AR改变丙酮酸运输以促进前列腺癌脂肪生成的机制。最重要的中心假设是，AR调节MPC增加进入线粒体的丙酮酸流量，从而通过增加肿瘤细胞的造脂能力来促进肿瘤的生长。这项建议的基本原理是，对前列腺癌中丙酮酸转运增加的机制进行表征，可能会使制定治疗操作丙酮酸通量的策略成为可能。这种治疗方法既可用于激素敏感型前列腺癌，也可用于治疗难治性去势耐药前列腺癌。为了实现总体目标，将通过追求以下三个具体目标来检验中心假设：1)除了使用基于质谱学的方法进行13C丙酮酸示踪外，还将通过实验修改MPC亚基组成和测量各种代谢终点来确定MPC亚基表达变化对丙酮酸通量的影响。2)通过体外测量肿瘤细胞增殖、侵袭能力和造脂能力来确定依赖于MPC的肿瘤特性。3)通过将稳定修饰MPC亚单位表达的前列腺癌细胞移植到裸鼠体内，或用MPC抑制剂UK5099治疗移植瘤小鼠，评估MPC干扰对前列腺癌体内生长的影响。关于结果，研究计划的完成将确定前列腺癌中观察到的改变的MPC亚单位表达模式的代谢和致癌后果。这一贡献的意义来自于前列腺癌中造脂底物运输的特征所带来的预期的翻译机会，这种破坏代表了疾病所有阶段的合理治疗策略。这项拟议的研究具有创新性，因为它专注于了解和破坏肿瘤特异性代谢底物的运输，而不是正常组织和肿瘤细胞所共有的酶活性。预计将重点扩大到包括底物贩运将拓宽癌症新陈代谢靶向的方法，同时在药物开发方面开辟新的研究领域。

 DESCRIPTION (provided by applicant): Androgen receptor (AR)-induced de-novo lipid synthesis enables the growth and survival of hormone sensitive and castrate-resistant prostate cancer cells, but the metabolic alterations mediated by AR to support lipogenesis in prostate cancer are poorly understood. Lipogenesis requires pyruvate to generate lipid precursors (e.g. citrate) and recent in-vivo imaging strategies have demonstrated that, in contrast to virtually all other tumors, prostate tumors take up pyruvate more rapidly and reliably than glucose. Further, a subunit of the mitochondrial pyruvate carrier (MPC), MPC2, is a direct AR target gene, suggesting a link between AR action pyruvate trafficking, and lipogenesis. The long-term goal of this project is the identification, characterization, and targeted disruption of critical mediatorsof prostate cancer metabolism. The overall objective of the current proposal is to determine the mechanism by which AR alters pyruvate trafficking to fuel lipogenesis in prostate cancer. The overarching central hypothesis is that AR regulates the MPC to increase pyruvate flux into mitochondria to enable oncogenic growth by increasing lipogenic capacity of tumor cells. The rationale of this proposal is that characterization of the mechanism underlying increased pyruvate trafficking in prostate cancer will likely enable the development of strategies to therapeutically manipulate pyruvate flux. Such treatments could be applied to both hormone sensitive and treatment refractory castrate-resistant prostate cancer. In order to accomplish the overall objective, the central hypothesis will be tested by pursuing the following three specific aims: 1) Determine the impact of altered MPC subunit expression on pyruvate flux by experimentally modifying MPC subunit composition and measuring a variety of metabolic endpoints in addition to using mass-spectroscopy-based methods to perform 13C pyruvate tracing. 2) Define MPC-dependent tumor properties using in-vitro measurements of tumor cell proliferation, invasive capacity, and lipogenic capacity. 3) Assess the impact of MPC perturbation on prostate tumor growth in-vivo by transplanting nude mice with prostate cancer cells harboring stable modifications to MPC subunit expression or treating xenografted mice with the MPC inhibitor UK5099. Regarding outcomes, completion of the research plan will define the metabolic and oncogenic consequences of the altered MPC subunit expression pattern observed in prostate cancer. The significance of this contribution derives from the expected translational opportunities made possible by the characterization of lipogenic substrate trafficking in prostate cancer, disruption of which represents a rational therapeutic strategy in al stages of the disease. The proposed research is innovative because it focuses on understanding and disrupting tumor-specific metabolic substrate trafficking rather than enzymatic activities common to normal tissues and tumor cells alike. It is expected this expansion of focus to include substrate trafficking will broaden the approach to metabolic targeting in cancer while opening new research horizons in drug development.