Molecular and functional evaluation of a novel HIF inhibitor, benzopyranyl 1,2,3-triazole compound

// Kyunghye Park 1 , Hye Eun Lee 1 , Sun Hee Lee 1 , Doohyun Lee 2 , Taeho Lee 2 , You Mie Lee 1, 2 1 BK21 Plus KNU Multi-Omics based Creative Drug Research Team, National Basic Research Laboratory of Vascular Homeostasis Regulation, Kyungpook National University, Buk-gu, 702-701, Daegu, Republic of Korea 2 College of Pharmacy, Research Institute of Pharmaceutical Sciences, Kyungpook National University, Buk-gu, 702-701, Daegu, Republic of Korea Correspondence to: You Mie Lee, email: lym@knu.ac.kr Keywords: HIF-1α inhibitor, chemical library, benzopyranyl 1,2,3-triazole Received: September 27, 2016      Accepted: December 01, 2016      Published: December 15, 2016 ABSTRACT Hypoxia occurs in a variety of pathological events, including the formation of solid tumors. Hypoxia-inducible factor (HIF)-1α is stabilized under hypoxic conditions and is a key molecule in tumor growth and angiogenesis. Seeking to develop novel cancer therapeutics, we investigated small molecules from our in-house chemical libraries to target HIF-1α. We employed a dual-luciferase assay that uses a luciferase (Luc) reporter vector harboring five copies of hypoxia-responsive element (HRE) in the promoter. Under hypoxic conditions that increased Luc reporter activity by four-fold, we screened 144 different compounds, nine of which showed 30–50% inhibition of hypoxia-induced Luc reporter activity. Among these, “Compound 12, a benzopyranyl 1,2,3-triazole” was the most efficient at inhibiting the expression of HIF-1α under hypoxic conditions, reducing its expression by 80%. Under hypoxic conditions, the half maximal IC 50 of the compound was 24 nM in HEK-293 human embryonic kidney cells, and 2 nM in A549 human lung carcinoma cells. Under hypoxic conditions, Compound 12 increased hydroxylated HIF-1α levels and HIF-1α ubiquitination, and also dose-dependently decreased HIF-1α target gene expression as well as vascular endothelial growth factor (VEGF) secretion. Furthermore, this compound inhibited VEGF-induced in vitro angiogenesis in human umbilical vein endothelial cells (HUVECs), and in vivo , it inhibited chick chorioallantoic membrane angiogenesis. In allogaft assays, cotreatment with Compound 12 and gefitinib significantly inhibited tumor growth and angiogenesis. Compound 12 can be a novel inhibitor of HIF-1α by accelerating its degradation, and shows much potential as an anti-cancer agent through its ability to suppress tumor growth and angiogenesis.