Heat shock protein 90 complex (HSP90 complex)

The Heat shock protein 90 (HSP90) complex in tumor cells represents a specialized, high-affinity state of the molecular chaperone that is distinct from its form in healthy tissues [Nature, 2003]. In the malignant environment, HSP90 is rewired into stable, high-molecular-weight assemblies known as the epichaperome, which are physically and functionally integrated with various co-chaperones and oncoproteins [Nature, 2016]. This activated complex is essential for the stability, folding, and maturation of numerous client proteins that drive cancer hallmarks, such as mutated kinases and transcription factors [Clinical Cancer Research, 2012]. Therapeutic targeting of these complexes typically involves small-molecule inhibitors that compete with ATP for binding to the N-terminal domain of HSP90 [Nature Reviews Cancer, 2005]. By disrupting the ATPase cycle, these inhibitors prevent the chaperone from stabilizing its clients, leading to their rapid degradation via the ubiquitin-proteasome pathway [Molecular Cancer Therapeutics, 2008]. This multi-target approach allows for the simultaneous inhibition of several oncogenic signaling pathways, though clinical success has been tempered by dose-limiting toxicities and compensatory cellular stress responses [Journal of Clinical Oncology, 2011].

Other names

Oncogenic HSP90EpichaperomeHSP90-multichaperone complexActivated HSP90Tumor-specific HSP90

Inhibition of the ATPase activity in the N-terminal domain of HSP90, which prevents the maturation of client proteins and leads to their ubiquitin-mediated proteasomal degradation [Nature Reviews Cancer, 2005].