Journal
JOURNAL OF BIOLOGICAL CHEMISTRY
Volume 294, Issue 10, Pages 3760-3771Publisher
AMER SOC BIOCHEMISTRY MOLECULAR BIOLOGY INC
DOI: 10.1074/jbc.RA118.004902
Keywords
cancer; cancer biology; hypoxia; hypoxia-inducible factor (HIF); mRNA decay; ccRCC; Egl-9 family hypoxia-inducible factor 3 (EGLN3); post-transcriptional regulation; prolyl hydroxylase PHD3; renal cell carcinoma
Categories
Funding
- Cancer Foundation Finland
- Sigrid Juselius Foundation
- Turku University Hospital [EVO1303]
- Helsinki University Hospital
- University of Turku Graduate School
- Finnish Cultural Foundation Varsinais-Suomi Regional fund
Ask authors/readers for more resources
Most clear cell renal cell carcinomas (ccRCCs) have inactivation of the von Hippel-Lindau tumor suppressor protein (pVHL), resulting in the accumulation of hypoxia-inducible factor -subunits (HIF-) and their downstream targets. HIF-2 expression is particularly high in ccRCC and is associated with increased ccRCC growth and aggressiveness. In the canonical HIF signaling pathway, HIF-prolyl hydroxylase 3 (PHD3) suppresses HIF-2 protein by post-translational hydroxylation under sufficient oxygen availability. Here, using immunoblotting and immunofluorescence staining, qRT-PCR, and siRNA-mediated gene silencing, we show that unlike in the canonical pathway, PHD3 silencing in ccRCC cells leads to down-regulation of HIF-2 protein and mRNA. Depletion of other PHD family members had no effect on HIF-2 expression, and PHD3 knockdown in non-RCC cells resulted in the expected increase in HIF-2 protein expression. Accordingly, PHD3 knockdown decreased HIF-2 target gene expression in ccRCC cells and expression was restored upon forced HIF-2 expression. The effect of PHD3 depletion was pinpointed to HIF2A mRNA stability. In line with these in vitro results, a strong positive correlation of PHD3 and HIF2A mRNA expression in ccRCC tumors was detected. Our results suggest that in contrast to the known negative regulation of HIF-2 in most cell types, high PHD3 expression in ccRCC cells maintains elevated HIF-2 expression and that of its target genes, which may enhance kidney cancer aggressiveness.
Authors
I am an author on this paper
Click your name to claim this paper and add it to your profile.
Reviews
Recommended
No Data Available