The PI3K/Akt Pathway Regulates Oxygen Metabolism via Pyruvate Dehydrogenase (PDH)-E1α Phosphorylation.
The PI3K/Akt Pathway Regulates Oxygen Metabolism via Pyruvate Dehydrogenase (PDH)-E1α Phosphorylation.
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DOI：
10.1158/1535-7163.mct-14-0888
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发表时间：
2015-08
影响因子：
5.7
通讯作者：
Maity A
中科院分区：
文献类型：
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作者：
Cerniglia GJ;Dey S;Gallagher-Colombo SM;Daurio NA;Tuttle S;Busch TM;Lin A;Sun R;Esipova TV;Vinogradov SA;Denko N;Koumenis C;Maity A
抑制PI3K/Akt通路可减少SQ20B人头颈癌异种移植物中的缺氧。我们开始了解这一观察结果背后的分子机制。我们使用克拉克电极和细胞外通量分析仪测量耗氧量。我们在各种药理学和基因操作后进行了这些测量。药理抑制PI3K/mTOR通路或基因抑制Akt/PI3K可使SQ20B和其他细胞系体外耗氧率（OCR）降低30-40%。药物抑制这一途径会增加Ser293上丙酮酸脱氢酶（PDH）复合物E1α亚基的磷酸化，从而抑制这一线粒体呼吸关键守门人的活性。在PTEN突变细胞系中以多西环素诱导的方式表达野生型PTEN，导致PDH-E1α磷酸化增加，OCR降低。通过抑制脱氢酶激酶（PDKs）抑制PDH-E1α磷酸化的二氯乙酸（DCA）预处理SQ20B细胞，逆转了PI3K/Akt/mTOR抑制下OCR的下降。同样，将外源性含有丝氨酸的PDH-E1α引入到丙氨酸突变中，这种突变不再受磷酸化调节，也减弱了PI3K/mTOR抑制所见的OCR下降。我们的研究结果强调了PI3K/mTOR通路和肿瘤细胞耗氧量之间的关联，这在一定程度上是由PDH磷酸化调节的。这些结果对于理解PI3K通路激活在肿瘤代谢中的作用以及设计使用该通路抑制剂的癌症治疗试验具有重要意义。
Inhibition of the PI3K/Akt pathway decreases hypoxia within SQ20B human head and neck cancer xenografts. We set out to understand the molecular mechanism underlying this observation. We measured oxygen consumption using both a Clark electrode and an extracellular flux analyzer. We made these measurements after various pharmacologic and genetic manipulations. Pharmacologic inhibition of the PI3K/mTOR pathway or genetic inhibition of Akt/PI3K decreased the oxygen consumption rate (OCR) in vitro in SQ20B and other cell lines by 30–40%. Pharmacologic inhibition of this pathway increased phosphorylation of the E1α subunit of the pyruvate dehydrogenase (PDH) complex on Ser293, which inhibits activity of this critical gatekeeper of mitochondrial respiration. Expressing wild type PTEN in a doxycycline-inducible manner in a cell line with mutant PTEN led to an increase in PDH-E1α phosphorylation and a decrease in OCR. Pre-treatment of SQ20B cells with dichloroacetate (DCA), which inhibits PDH-E1α phosphorylation by inhibiting dehydrogenase kinases (PDKs), reversed the decrease in OCR in response to PI3K/Akt/mTOR inhibition. Likewise, introduction of exogenous PDH-E1α that contains serine to alanine mutations, which can no longer be regulated by phosphorylation, also blunted the decrease in OCR seen with PI3K/mTOR inhibition. Our findings highlight an association between the PI3K/mTOR pathway and tumor cell oxygen consumption that is regulated in part by PDH phosphorylation. These results have important implications for understanding the effects PI3K pathway activation in tumor metabolism and also in designing cancer therapy trials that use inhibitors of this pathway.