Combined targeting of PDK1 and EGFR triggers regression of glioblastoma by reversing the Warburg effect.

Abstract

Glioblastoma multiforme is the most aggressive primary brain tumor in adults. Overexpression of the EGF receptor (EGFR) is recognized as a widespread oncogenic signature in glioblastoma multiforme, but the complexity of its contributions is not fully understood, nor the most effective ways to leverage anti-EGFR therapy in this setting. Hypoxia is known to drive the aggressive character of glioblastoma multiforme by promoting aerobic glycolysis rather than pyruvate oxidation carried out in mitochondria (OXPHOS), a phenomenon termed the Warburg effect, which is a general feature of oncogenesis. In this study, we report that hypoxia drives expression of the pyruvate dehydrogenase kinase (PDK1) and EGFR along with the hypoxia-inducing factor (HIF)-1α in human glioblastoma multiforme cells. PDK1 is a HIF-1-regulated gene and our findings indicated that hypoxia-induced PDK1 expression may promote EGFR activation, initiating a feed-forward loop that can sustain malignant progression. RNAi-mediated attenuation of PDK1 and EGFR lowered PDK1-EGFR activation and decreased HIF-1α expression, shifting the Warburg phenotype to OXPHOS and inhibiting glioblastoma multiforme growth and proliferation. In clinical specimens of glioblastoma multiforme, we found that immunohistochemical expression of PDK1, EGFR, and HIF-1α were elevated in glioblastoma multiforme specimens when compared with normal brain tissues. Collectively, our studies establish PDK1 as a key driver and candidate therapeutic target in glioblastoma multiforme.

• Authors: Kiran Kumar Velpula, Arnima Bhasin, Swapna Asuthkar, Andrew J Tsung
• Journal: Cancer research (Cancer Res) Vol. 73 Issue 24 Pg. 7277-89 (Dec 15 2013) ISSN: 1538-7445 [Electronic] United States
• PMID: 24148623 (Publication Type: Journal Article, Research Support, Non-U.S. Gov't)
• Copyright: ©2013 AACR.

Chemical References

• PDK1 protein, human
• Pdk1 protein, mouse
• Pyruvate Dehydrogenase Acetyl-Transferring Kinase
• Dichloroacetic Acid
• EGFR protein, human
• ErbB Receptors
• Protein Serine-Threonine Kinases

Topics

• Animals
• Brain Neoplasms (drug therapy, enzymology, pathology)
• Cell Hypoxia (physiology)
• Cell Line, Tumor
• Cell Transformation, Neoplastic
• Dichloroacetic Acid (pharmacology)
• ErbB Receptors (antagonists & inhibitors, metabolism)
• Female
• Glioblastoma (drug therapy, enzymology, pathology)
• Humans
• Mice
• Mice, Nude
• Protein Serine-Threonine Kinases (metabolism)
• Pyruvate Dehydrogenase Acetyl-Transferring Kinase
• Signal Transduction