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Deregulated accumulation of hypoxia-inducible factor-1α (HIF-1α) is a hallmark of many solid tumors. Directly targeting HIF-1α for therapeutics is challenging. Our finding that HIF-1α regulates secretion of heat shock protein-90α (Hsp90α) for cell migration raises the exciting possibility that targeting the secreted Hsp90α from HIF-1α-positive tumors has a better clinical outlook. Using the HIF-1α-positive and metastatic breast cancer cells MDA-MB-231, we show that down-regulation of the deregulated HIF-1α blocks Hsp90α secretion and invasion of the cells. Reintroducing an active, but not an inactive, HIF-1α into endogenous HIF-1α-depleted cells rescues both Hsp90α secretion and invasion. Inhibition of Hsp90α secretion, neutralization of secreted Hsp90α action, or removal of the cell surface LRP-1 receptor for secreted Hsp90α reduces the tumor cell invasion in vitro and lung colonization and tumor formation in nude mice. Furthermore, we localized the tumor-promoting effect to a 115-amino acid region in secreted Hsp90α called F-5. Supplementation with F-5 is sufficient to bypass the blockade of HIF-1α depletion and resumes invasion by the tumor cells under serum-free conditions. Because normal cells do not secrete Hsp90α in the absence of stress, drugs that target F-5 should be more effective and less toxic in treatment of HIF-1α-positive tumors in humans.
Pubmed ID: 22190738
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Cell line MDA-MB-435 is a Cancer cell line with a species of origin Homo sapiens (Human)
View all literature mentionsCell line MDA-MB-231 is a Cancer cell line with a species of origin Homo sapiens (Human)
View all literature mentionsCell line U-251MG is a Cancer cell line with a species of origin Homo sapiens (Human)
View all literature mentionsCell line MDA-MB-468 is a Cancer cell line with a species of origin Homo sapiens (Human)
View all literature mentionsCell line MDA-MB-231 is a Cancer cell line with a species of origin Homo sapiens (Human)
View all literature mentionsMus musculus with name Crl:NU(NCr)-Foxn1nu from IMSR.
View all literature mentionsCell line MCF-7 is a Cancer cell line with a species of origin Homo sapiens (Human)
View all literature mentions