Heat shock protein 90 alpha (Hsp90α) (Hsp90α)

Heat shock protein 90 alpha (Hsp90α) is a molecular chaperone that, while traditionally known for its intracellular role in protein folding and stability, is actively secreted or displayed on the surface of various cancer cells (UniProt P07900). In the extracellular environment (eHsp90α), it plays a critical role in promoting tumor cell invasion and metastasis by interacting with the LRP1 (CD91) receptor and activating matrix metalloproteinases like MMP-2 (PMID: 23548888). Unlike intracellular Hsp90, which is essential for the survival of all cells, eHsp90α is specifically upregulated in response to stress factors such as hypoxia and TGF-beta within the tumor microenvironment (PMID: 26154018). Targeting eHsp90α with cell-impermeable small molecules or monoclonal antibodies aims to inhibit the metastatic cascade without the systemic toxicities—such as hepatotoxicity and ocular damage—associated with pan-Hsp90 inhibitors (PMID: 30103347). Clinical interest focuses on its utility as both a diagnostic biomarker for cancer progression and a therapeutic target for preventing the spread of aggressive solid tumors. Current research explores its role in various malignancies, including breast, lung, and skin cancers, where its surface expression correlates with increased malignancy and poor prognosis.

Other names

extracellular Hsp90eHsp90HSP90AA1Heat shock 90kDa protein 1 alphaLipopolysaccharide-associated protein 2LAP-2HSPNHsp89 alpha

Inhibition of extracellular chaperone activity and blocking of the Hsp90α-LRP1 signaling axis to prevent matrix metalloproteinase activation and tumor cell migration.