title: RUNX3 inhibits hypoxia-inducible factor-1α protein stability by interacting with prolyl hydroxylases in gastric cancer cells.
abstract: RUNX3 is silenced by histone modification and hypoxia-inducible factor (HIF)-1α is stabilized under hypoxia, but little is known of cross-talk between RUNX3 and HIF-1α under hypoxia. In the present study, the authors investigated the effect of RUNX3 on HIF-1α stability in gastric cancer cells. RUNX3 overexpression was found to downregulate HIF-1α stability under normoxic and hypoxic conditions. Furthermore, the activity of a luciferase reporter containing five copies of vascular endothelial growth factor (VEGF) promoter hypoxia-responsive element (5 × HRE) and the amount of secreted VEGF, were diminished in RUNX3-expressing but increased in RUNX3-knockdown cells. When expression of RUNX3 was recovered using epigenetic reagents the expressions of HIF-1α and VEGF were clearly suppressed under hypoxic conditions. RUNX3 also significantly attenuated the half-life of HIF-1α protein, and induced the cytosolic localization and ubiquitination of HIF-1α. In addition, RUNX3 directly interacted with the C-terminal activation domain of HIF-1α and prolyl hydroxylase (PHD) 2 and enhanced the interaction between HIF-1α and PHD2, which potentiated proline hydroxylation and promoted the degradation of HIF-1α. Furthermore, RUNX3 overexpression significantly inhibited hypoxia-induced angiogenesis in vitro and in vivo. Taken together, these results suggest that RUNX3 destabilizes HIF-1α protein by promoting the proline hydroxylation of HIF-1α through binding to HIF-1α/PHD2. RUNX3 appears to be a novel suppressor of HIF-1α and of hypoxia-mediated angiogenesis in gastric cancer cells.
authors.affiliation: 1] School of Life Sciences and Biotechnology, College of Natural Sciences, Kyungpook National University, Daegu, Republic of Korea [2] College of Pharmacy, Kyungpook National University, Daegu, Republic of Korea [3] Research Institute of Pharmaceutical Sciences, Kyungpook National University, Daegu, Republic of Korea.
authors.forename: S H
authors.initials: SH
authors.lastname: Lee
authors.affiliation: School of Medicine, Chungbook National University, Cheongju, Republic of Korea.
authors.forename: S C
authors.initials: SC
authors.lastname: Bae
authors.affiliation: College of Pharmacy, Seoul National University, Seoul, Republic of Korea.
authors.forename: K W
authors.initials: KW
authors.lastname: Kim
authors.affiliation: 1] College of Pharmacy, Kyungpook National University, Daegu, Republic of Korea [2] Research Institute of Pharmaceutical Sciences, Kyungpook National University, Daegu, Republic of Korea.
authors.forename: Y M
authors.initials: YM
authors.lastname: Lee
mesh_terms: D015687:Cell Hypoxia / Q000235:genetics; D045744:Cell Line, Tumor; D050677:Core Binding Factor Alpha 3 Subunit / Q000502:physiology*; D006801:Humans; D006900:Hydroxylation; D051795:Hypoxia-Inducible Factor 1, alpha Subunit / Q000378:metabolism*; D064828:Prolyl Hydroxylases / Q000378:metabolism*; D012333:RNA, Messenger / Q000235:genetics; D013274:Stomach Neoplasms / Q000201:enzymology / Q000378:metabolism* / Q000473:pathology; D054875:Ubiquitination; D042461:Vascular Endothelial Growth Factor A / Q000235:genetics
chemical_list: D050677:Core Binding Factor Alpha 3 Subunit; D051795:Hypoxia-Inducible Factor 1, alpha Subunit; D012333:RNA, Messenger; C493729:Runx3 protein, human; D042461:Vascular Endothelial Growth Factor A; D064828:Prolyl Hydroxylases