Al's Comment:
The concept of cytomegalovirus being associated with GBMs is controversial. Some researchers say 100% of GBM samples have it, others say none of them have it. I tend to agree with the ones that say it is very common in GBM samples. IF that is true, this study may show how CMV can promote the formation of tumors. And that opens the door for treatments. There is already an approved drug that fights CMV, and there is a brain tumor vaccine under development that targets the CMV. Preliminary results look good. This study also identifies other downstream targets which may be exploited.
Posted on: 09/08/2016
. Oncotarget. 2016 Sep 1. doi: 10.18632/oncotarget.11817. [Epub ahead of print]
Human cytomegalovirus encoded chemokine receptor US28 activates the HIF-1α/PKM2 axis in glioblastoma cells.
de Wit RH1, Muji?-Deli? A1, van Senten JR1, Ramos AF 2, Siderius M1, Smit MJ1.
Author information:
1Division of Medicinal Chemistry, Amsterdam Institute for Molecules Medicines and Systems, Vrije Universiteit Amsterdam, De Boelelaan, Amsterdam, The Netherlands.
2Division of Cell Biology, Faculty of Medicine, Universidad Complutense de Madrid, Madrid, Spain.
Abstract
The human cytomegalovirus (HCMV) encoded chemokine receptor US28 promotes tumorigenesis through activation of various proliferative and angiogenic signaling pathways. Upon infection, US28 displays constitutive activity and signals in a G protein-dependent manner, hijacking the host's cellular machinery. In tumor cells, the hypoxia inducible factor-1α/pyruvate kinase M2 (HIF-1α/PKM2) axis plays an important role by supporting proliferation, angiogenesis and reprogramming of energy metabolism. In this study we show that US28 signaling results in activation of the HIF-1α/PKM2 feedforward loop in fibroblasts and glioblastoma cells. The constitutive activity of US28 increases HIF-1 protein stability through a Gαq-, CaMKII- and Akt/mTOR-dependent mechanism. Furthermore, we found that VEGF and lactate secretion are increased and HIF-1 target genes, glucose transporter type 1 (GLUT1) and glyceraldehyde-3-phosphate dehydrogenase (GAPDH), involved in glucose metabolism, are upregulated in US28 expressing cells. In addition, PKM2 is phosphorylated and found to be in a tumor-associated dimeric state upon US28 expression. Also in HCMV-infected cells HIF-1 activity is enhanced, which in part is US28-dependent. Finally, increased proliferation of cells expressing US28 is abolished upon inhibition of the HIF-1α/PKM2 cascade. These data highlight the importance of HIF-1α and PKM2 in US28-induced proliferation, angiogenesis and metabolic reprogramming.
PMID: 27602585 [PubMed - as supplied by publisher]
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