Biguanide Sensitivity of Glioma Stem Cells

抑制线粒体复合体I活性的双胍基二甲双胍现在超过200 肿瘤学临床试验。在这项提案中，我们将确定如何提高癌细胞对 二甲双胍疗法。细胞能量的产生主要有两种方式--糖酵解和线粒体 葡萄糖和脂肪酸的氧化。二甲双胍抑制线粒体能量的产生。因此，当 切换到低糖介质(减少糖酵解)，癌细胞对二甲双胍敏感。 然而，组织中的生理性葡萄糖浓度明显低于大多数细胞中使用的浓度。 培养研究发现，肿瘤组织中的葡萄糖浓度甚至更低。在这个葡萄糖的生理范围内， 癌细胞维持较高的糖酵解率，调节癌细胞糖酵解的基因可能抵抗双胍 当线粒体被抑制时，通过上调代偿性糖酵解的作用。因此，身份识别和 抑制这些基因可能会增加癌细胞对双胍类化合物的易感性。尽管在其他方面承诺 对于癌症，我们的数据表明，胶质瘤干细胞(GSCs)在生理葡萄糖条件下对双胍类化合物具有耐药性。 我们发现，细胞能量感受器AMP激酶(AMPK)在应激过程中增强糖酵解。 心肌和骨骼肌被GSCs用于最佳糖酵解。我们建议通过以下方式测试这些机制 AMPK在体外和体内调节GSCs的糖酵解。通过剂量递增药理学 在小鼠中的研究我们将确定携带脑瘤的小鼠对二甲双胍的最大耐受量，定量 二甲双胍的血浆浓度，以及在正常脑和肿瘤组织中的浓度。我们将测试 如果GSCs中AMPK的基因抑制减少糖酵解，则会抑制增殖和肿瘤生长，并 提高了二甲双胍的敏感性。

The biguanide metformin that inhibits mitochondrial complex I activity is now in over 200 oncology clinical trials. In this proposal we will determine how to enhance cancer cell sensitivity towards metformin therapy. There are two principal modes of cellular energy production – glycolysis and mitochondrial oxidation of glycose and fatty acids. Metformin inhibits mitochondrial energy production. Therefore, when switched to a low glucose medium (that reduces glycolysis), cancer cells become sensitized to metformin. Physiological glucose concentration in tissues is however significantly lower compared to that used in most cell culture studies and glucose concentration is even lower in tumor tissues. At this physiological range of glucose, cancer cells maintain high glycolytic rate and genes that regulate cancer cell glycolysis may resist biguanide action by upregulating compensatory glycolysis when mitochondria is inhibited. Therefore, identification and inhibition of such genes may enhance cancer cell liability towards biguanides. Despite promise in other cancers, our data shows that glioma stem cells (GSCs) are resistant to biguanides at physiological glucose. We discovered that the cellular energy sensor AMP kinase (AMPK) that augments glycolysis during stress in cardiac and skeletal muscle is co-opted by GSCs for optimal glycolysis. We propose to test the mechanisms by which AMPK regulates glycolysis in GSCs in vitro and in vivo. Through dose escalation pharmacological studies in mice we will determine maximum tolerated metformin dose in brain tumor-bearing mice, quantitate metformin plasma levels, and metformin concentrations attained in normal brain and tumor tissue. We will test if genetic inhibition of AMPK in GSCs reduces glycolysis, suppress proliferation and tumor growth and improves metformin sensitivity.