Hypoxia-inducible factor 2 alpha promoter G-quadruplex (HIF-2a G4)

The Hypoxia-inducible factor 2 alpha (HIF-2 alpha) promoter G-quadruplex is a non-canonical, four-stranded nucleic acid structure located within the guanine-rich regulatory region of the EPAS1 gene. This structural motif acts as a molecular switch that modulates the transcription of HIF-2 alpha, a transcription factor essential for the cellular response to low-oxygen environments. In normal physiology, HIF-2 alpha regulates genes involved in angiogenesis, red blood cell production, and metabolic adaptation; however, in many cancers, such as clear cell renal cell carcinoma, it is constitutively overexpressed and drives tumor progression. Small-molecule ligands, such as the experimental compound CL67, are designed to bind and stabilize this G-quadruplex structure, creating a physical barrier that prevents the transcriptional machinery from accessing the gene. This stabilization leads to the downregulation of EPAS1 mRNA and a subsequent decrease in HIF-2 alpha protein levels, offering a potential strategy to inhibit tumor growth and vascularization. Therapeutic challenges for this target include achieving high selectivity for the EPAS1 G-quadruplex over other genomic structures and managing potential systemic toxicity from the broad inhibition of hypoxia-responsive pathways.

Other names

EPAS1 G-quadruplexHIF-2 alpha G4EPAS1 promoter G-quadruplexHypoxia-inducible factor 2-alpha gene G-quadruplexEndothelial PAS domain-containing protein 1 promoter G-quadruplex

Ligand-mediated stabilization of the G-quadruplex structure within the EPAS1 promoter, which sterically inhibits the binding of transcription factors or the progression of RNA polymerase, thereby reducing the transcription and expression of the HIF-2 alpha protein.