Heat shock protein 90–Hypoxia-inducible factor 1-alpha complex (HSP90–HIF-1α)

The Heat shock protein 90–Hypoxia-inducible factor 1-alpha (HSP90–HIF-1α) complex is a vital regulatory assembly where the molecular chaperone HSP90 maintains the stability and transcriptional activity of HIF-1α (Isaacs et al., 2002, J. Biol. Chem.). HIF-1α is a master regulator of the cellular response to low oxygen, but it is highly unstable and typically targeted for degradation. HSP90 binds to the PAS-B domain of HIF-1α, shielding it from oxygen-independent degradation pathways, such as those mediated by the RACK1/Elongin C complex (Liu et al., 2007, Mol. Cell). In the context of oncology, this complex is frequently exploited by solid tumors to survive in hypoxic microenvironments by upregulating genes for angiogenesis and anaerobic metabolism. Therapeutic strategies involve using small-molecule inhibitors that bind to the N-terminal ATP-binding pocket of HSP90, which triggers the ubiquitination and subsequent proteasomal degradation of HIF-1α (Neckers & Workman, 2012, Clin. Cancer Res.). While these inhibitors show potent anti-tumor activity in preclinical models, clinical application has been hindered by toxicities such as liver damage and visual disturbances. Monitoring biomarkers like VEGF and HSP70 is often employed to assess the efficacy and biological impact of disrupting this complex. Targeting this interaction remains a significant area of research for overcoming tumor resistance to conventional therapies.

Other names

HSP90-HIF1A complexHSP90-HIF-1 alpha complexHSP90-HIF1 complexHSP90-HIF-1α interaction

HSP90 inhibitors bind to the N-terminal ATP-binding domain of HSP90, preventing the chaperone from stabilizing its client proteins. This disruption leads to the recruitment of E3 ubiquitin ligases, such as RACK1, which target HIF-1α for proteasomal degradation in an oxygen-independent and VHL-independent manner (Liu et al., 2007, Mol. Cell; Neckers & Workman, 2012, Clin. Cancer Res.).