Identification of a novel small-molecule inhibitor of the hypoxia-inducible factor 1 pathway.
Hypoxia-inducible factor 1 (HIF-1) is the central mediator of cellular responses to low oxygen and has recently become an important therapeutic target for solid tumor therapy. Inhibition of HIF-1 is expected to result in the attenuation of hypoxia-inducible genes, which are vital to many aspects of tumor biology, including adaptative responses for survival under anaerobic conditions. To identify small molecules inhibiting the HIF-1 pathway, we did a biological screen on a 10,000-membered natural product-like combinatorial library. The compounds of the library, which share a 2,2-dimethylbenzopyran structural motif, were tested for their ability to inhibit the hypoxic activation of an alkaline phosphatase reporter gene under the control of hypoxia-responsive elements in human glioma cells. This effort led to the discovery of 103D5R, a novel small-molecule inhibitor of HIF-1alpha. 103D5R markedly decreased HIF-1alpha protein levels induced by hypoxia or cobaltous ions in a dose- and time-dependent manner, whereas minimally affecting global cellular protein expression levels, including that of control proteins such as HIF-1beta, IkappaBalpha, and beta-actin. The inhibitory activity of 103D5R against HIF-1alpha was clearly shown under normoxia and hypoxia in cells derived from different cancer types, including glioma, prostate, and breast cancers. This inhibition prevented the activation of HIF-1 target genes under hypoxia such as vascular endothelial growth factor (VEGF) and glucose transporter-1 (Glut-1). Investigations into the molecular mechanism showed that 103D5R strongly reduced HIF-1alpha protein synthesis, whereas HIF-1alpha mRNA levels and HIF-1alpha degradation were not affected. 103D5R inhibited the phosphorylation of Akt, Erk1/2, and stress-activated protein kinase/c-jun-NH(2)-kinase, without changing the total levels of these proteins. Further studies on the mechanism of action of 103D5R will likely provide new insights into its validity/applicability for the pharmacologic targeting of HIF-1alpha for therapeutic purposes.
Tan
Chalet
C
Department of Neurosurgery, Emory University School of Medicine, Atlanta, GA 30322, USA.
de Noronha
Rita G
RG
Roecker
Anthony J
AJ
Pyrzynska
Beata
B
Khwaja
Fatima
F
Zhang
Zhaobin
Z
Zhang
Huanchun
H
Teng
Quincy
Q
Nicholson
Ainsley C
AC
Giannakakou
Paraskevi
P
Zhou
Wei
W
Olson
Jeffrey J
JJ
Pereira
M Manuela
MM
Nicolaou
K C
KC
Van Meir
Erwin G
EG
D001578:Benzopyrans / Q000494:pharmacology*; D001685:Biological Factors / Q000494:pharmacology; D001943:Breast Neoplasms / Q000188:drug therapy; D045744:Cell Line, Tumor; D020650:Combinatorial Chemistry Techniques; D004268:DNA-Binding Proteins / Q000037:antagonists & inhibitors* / Q000096:biosynthesis / Q000235:genetics / Q000378:metabolism; D004305:Dose-Response Relationship, Drug; D005909:Glioblastoma / Q000188:drug therapy; D006801:Humans; D051793:Hypoxia-Inducible Factor 1; D051795:Hypoxia-Inducible Factor 1, alpha Subunit; D008297:Male; D009687:Nuclear Proteins / Q000037:antagonists & inhibitors* / Q000096:biosynthesis / Q000235:genetics / Q000378:metabolism; D011471:Prostatic Neoplasms / Q000188:drug therapy; D012333:RNA, Messenger / Q000096:biosynthesis / Q000235:genetics; D014157:Transcription Factors / Q000037:antagonists & inhibitors* / Q000096:biosynthesis / Q000235:genetics / Q000378:metabolism; D014158:Transcription, Genetic / Q000187:drug effects; D042461:Vascular Endothelial Growth Factor A / Q000037:antagonists & inhibitors / Q000096:biosynthesis / Q000235:genetics
C496879:103D5R; D001578:Benzopyrans; D001685:Biological Factors; D004268:DNA-Binding Proteins; C497442:HIF1A protein, human; D051793:Hypoxia-Inducible Factor 1; D051795:Hypoxia-Inducible Factor 1, alpha Subunit; D009687:Nuclear Proteins; D012333:RNA, Messenger; D014157:Transcription Factors; D042461:Vascular Endothelial Growth Factor A