Phosphoinositides and Cancer Metabolism

项目摘要： 25年前，我们发现了磷脂酰肌醇3-激酶或PI 3 K。迄今为止，已有30多个PI 3 K 抑制剂已进入临床试验，靶向PI 3 K δ的抑制剂（idelalisib）最近被批准用于 治疗B细胞淋巴瘤。我们的研究和其他实验室在过去25年的研究表明， PI 3 K通路进化为控制细胞生长，主要通过调节细胞代谢。的 本申请的重点是了解磷酸肌醇激酶 控制细胞新陈代谢。我们希望发现药物干预癌症的新靶点， 用于预测可能对通路抑制剂有反应的患者的生物标志物，以及对 对途径抑制剂的抗性机制。拟议的研究福尔斯分为三类：1） 评价PI 3 K控制葡萄糖代谢和核苷酸合成的机制， 开发生物标志物，以识别可能对PI 3 K抑制剂有反应的患者，并预测药物 可能比单一药剂更有效的组合。我们最近发现， 激活PI 3 K对葡萄糖代谢的主要作用是激活Rac 1，随后激活 由于醛缩酶A从肌动蛋白细胞骨架释放，因此可抑制醛缩酶A。重要的是，我们发现醛缩酶A 脱氧核苷酸三磷酸的合成需要激活，其速率需要S期进展， p53和BRCA 1或PTEN突变的肿瘤，解释了为什么这些肿瘤可以通过 PI 3 K + PARP抑制剂，但AKT + PARP抑制剂不能。2)磷脂酰肌醇-5- 磷酸4-激酶（PIP 4K 2A和PIP 4K 2B）作为缺乏p53功能的癌症的治疗靶点 以及确定这些激酶成为肿瘤必需的生化机制 当p53缺陷时生长。PIP 4 K2 A和B从低丰度和低丰度的PIP 4 K2 A和PIP 4 K2 B产生PI-4，5-P2。 最近，我们令人惊讶地观察到PIP 4K 2B −/− TP 53-/-小鼠死亡， 早期胚胎重要的是，PIP 4K 2A-/-、PIP 4K 2B +/-、TP 53-/-小鼠是存活的并且很少发生癌症， 提示PIP 4 K2 A/B抑制剂可能有效治疗具有p53遗传畸变的癌症。 我们的研究表明，敲低PIP 4 K2 A和B会导致p53突变癌细胞的代谢应激。我们 我建议确定PIP 4 K2 A和B的缺失仅导致代谢应激的机制， p53的缺失。3)PIP 4 K2 A和B抑制剂的鉴定和表征以及评价 临床前模型中的抑制剂，以提供临床前概念验证研究， 让这些抑制剂进入人类癌症试验。我们已经确定了PIP 4K 2A的抑制剂， B，并表明它们模拟了敲除或敲低这些酶的影响， p53突变细胞系的生长。我们将评估这些抑制剂是否靶向，并确定是否 它们在体内具有使它们可用于治疗具有p53突变的癌症的功效/毒性比。

Project Abstract: More than 25 years ago we discovered the phosphoinositide 3-kinases or PI3K. To date more than 30 PI3K inhibitors have entered clinical trials and an inhibitor (idelalisib) that targets PI3Kδ was recently approved for treating B cell lymphomas. Our research and research from other labs over the past 25 years has revealed that the PI3K pathway evolved to control cell growth, primarily through regulation of cellular metabolism. The focus of this application is to understand the biochemical mechanisms by which phosphoinositide kinases control cellular metabolism. We expect to uncover new targets for pharmaceutical intervention in cancers, new biomarkers for predicting patients who are likely to respond to pathway inhibitors, and new insight into mechanisms of resistance to pathway inhibitors. The proposed research falls into three categories: 1) Evaluate the mechanism by which PI3K controls glucose metabolism and nucleotide synthesis and develop biomarkers to identify patients who are likely to respond to PI3K inhibitors and predict drug combinations that are likely to be more effective than single agents. We have recently found that the major effect of activating PI3K on glucose metabolism is activation of Rac1 and consequent activation of aldolase A due to release of aldolase A from the actin cytoskeleton. Importantly we find that aldolase A activation is required for deoxy-nucleotide triphosphate synthesis at rates needed for S phase progression in tumors with p53 and BRCA1 or PTEN mutations, explaining why these tumors can be dramatically shrunk by PI3K plus PARP inhibitors but not by AKT plus PARP inhibitors. 2) Evaluation of phosphatidylinositol-5- phosphate 4-kinases (PIP4K2A and PIP4K2B) as therapeutic targets in cancers lacking p53 function and determination of the biochemical mechanism by which these kinases become essential for tumor growth when p53 is defective. PIP4K2A and B generate PI-4,5-P2 from the low abundant and poorly characterized lipid PI-5-P. Recently we made the surprising observation that PIP4K2B−/− TP53-/- mice die as early embryos. Importantly, PIP4K2A-/-, PIP4K2B+/-, TP53-/- mice are viable and rarely develop cancers, suggesting that PIP4K2A/B inhibitors might be effective for treating cancers with genetic aberrations in p53. Our studies show that knocking down PIP4K2A and B causes metabolic stress in p53 mutant cancer cells. We propose to determine the mechanism by which loss of PIP4K2A and B only causes metabolic stress in the context of loss of p53. 3) Identification and characterization of PIP4K2A and B inhibitors and evaluation of inhibitors in pre-clinical models in order to provide pre-clinical proof of concept studies that will allow these inhibitors to progress into human cancer trials. We have identified inhibitors of PIP4K2A and B and shown that they mimic the effects of knockout or knockdown of these enzymes in regard to affecting growth of p53 mutant cell lines. We will evaluate whether these inhibitors are on target and determine whether they have an efficacy/toxicity ratio in vivo that would make them useful for treating cancers with p53 mutations.