Glycolytic glioma cells with active glycogen synthase are sensitive to PTEN and inhibitors of PI3K and gluconeogenesis
Glycolytic glioma cells with active glycogen synthase are sensitive to PTEN and inhibitors of PI3K and gluconeogenesis
复制标题
DOI：
10.1038/labinvest.3700355
复制
发表时间：
2005-12-01
影响因子：
5
通讯作者：
Pollack, IF
中科院分区：
文献类型：
--
作者：
Beckner, ME;Gobbel, GT;Pollack, IF
糖酵解增加是恶性肿瘤的特征。先前，我们用线粒体抑制剂证明糖酵解ATP的产生足以支持黑色素瘤细胞的迁移。近年来，我们发现U87胶质瘤（星形细胞瘤）细胞形成的假足中糖酵解酶丰富，部分酶升高。在这项研究中，我们检测了U87和LN229胶质瘤细胞在线粒体被氮化钠抑制或1% O-2限制时的细胞迁移、粘附（迁移的一个步骤）和Matrigel侵袭。不论有无线粒体抑制，细胞迁移、粘附和侵袭均具有可比性。在发现糖酵解可以单独支持胶质瘤细胞迁移后，研究了星形胶质细胞中葡萄糖代谢的独特特征。星形胶质细胞通过糖异生和糖原结合去除糖酵解抑制剂乳酸的能力导致考虑支持性基因突变。磷酸酶和紧张素同源物（PTEN）的缺失使糖原合成酶激酶-3 （GSK3）的组成性抑制释放糖生成。我们假设胶质瘤中的糖酵解可以支持侵袭性迁移，特别是当PTEN对磷脂酰肌醇-3激酶(PI3K)/Akt通路的调节缺失导致GSK3的抑制时。研究了PTEN突变的U87细胞的迁移，以释放细胞外乳酸，并通过糖异生、PTEN的丧失和活性PI3K的支持。乳酸水平趋于稳定，磷酸化变化证实，当细胞仅依赖糖酵解时，PI3K/Akt通路和糖原合成酶被激活。PTEN转染可抑制糖酵解U87细胞的迁移和GSK3的磷酸化。wortmannin和metformin也分别通过抑制PI3K和糖异生来抑制糖酵解迁移。这些发现证实糖酵解性胶质瘤细胞可以侵袭性迁移，PTEN的丧失是支持性的，相关的下游效应包括活化的糖原电位。
Increased glycolysis is characteristic of malignancy. Previously, with a mitochondrial inhibitor, we demonstrated that glycolytic ATP production was sufficient to support migration of melanoma cells. Recently, we found that glycolytic enzymes were abundant and some were increased in pseudopodia formed by U87 glioma ( astrocytoma) cells. In this study, we examined cell migration, adhesion ( a step in migration), and Matrigel invasion of U87 and LN229 glioma cells when their mitochondria were inhibited with sodium azide or limited by 1% O-2. Cell migration, adhesion, and invasion were comparable, with and without mitochondrial inhibition. Upon discovering that glycolysis alone can support glioma cell migration, unique features of glucose metabolism in astrocytic cells were investigated. The ability of astrocytic cells to remove lactate, the inhibitor of glycolysis, via gluconeogenesis and incorporation into glycogen led to consideration of supportive genetic mutations. Loss of phosphatase and tensin homolog ( PTEN) releases glycogenesis from constitutive inhibition by glycogen synthase kinase-3 (GSK3). We hypothesize that glycolysis in gliomas can support invasive migration, especially when aided by loss of PTEN's regulation on the phosphatidylinositol-3 kinase (PI3K)/Akt pathway leading to inhibition of GSK3. Migration of PTEN-mutated U87 cells was studied for release of extracellular lactic acid and support by gluconeogenesis, loss of PTEN, and active PI3K. Lactic acid levels plateaued and phosphorylation changes confirmed activation of the PI3K/Akt pathway and glycogen synthase when cells relied only on glycolysis. Glycolytic U87 cell migration and phosphorylation of GSK3 were inhibited by PTEN transfection. Glycolytic migration was also suppressed by inhibiting PI3K and gluconeogenesis with wortmannin and metformin, respectively. These findings confirm that glycolytic glioma cells can migrate invasively and that the loss of PTEN is supportive, with activated glycogenic potential included among the relevant downstream effects.