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Ibrahim, N O; Hahn, T; Franke, C; Stiehl, D P; Wirthner, R; Wenger, R H; Katschinski, D M (2005). Induction of the hypoxia-inducible factor system by low levels of heat shock protein 90 inhibitors. Cancer Research, 65(23):11094-11100.

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The heterodimeric hypoxia-inducible factor-1 (HIF-1) is involved in key steps of tumor progression and therapy resistance and thus represents an attractive antitumor target. Because heat shock protein 90 (HSP90) plays an important role in HIF-1alpha protein stabilization and because HSP90 inhibitors are currently being tested in clinical phase I trials for anticancer treatment, we investigated their role as anti-HIF-1alpha agents. Surprisingly, low-dose (5-30 nmol/L) treatment of HeLa cells with three different HSP90 inhibitors (17-AAG, 17-DMAG, and geldanamycin) increased HIF-1-dependent reporter gene activity, whereas higher doses (1-3 micromol/L) resulted in a reduction of hypoxia-induced HIF-1 activity. In line with these data, low-dose treatment with HSP90 inhibitors increased and high-dose treatment reduced hypoxic HIF-1alpha protein levels, respectively. HIF-1alpha protein stabilized by HSP90 inhibitors localized to the nucleus. As a result of HSP90-modulated HIF-1 activity, the levels of the tumor-relevant HIF-1 downstream targets carbonic anhydrase IX, prolyl-4-hydroxylase domain protein 3, and vascular endothelial growth factor were increased or decreased after low-dose or high-dose treatment, respectively. Bimodal effects of 17-AAG on vessel formation were also seen in the chick chorioallantoic membrane angiogenesis assay. In summary, these results suggest that dosage will be a critical factor in the treatment of tumor patients with HSP90 inhibitors.


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Additional indexing

Item Type:Journal Article, refereed
Communities & Collections:04 Faculty of Medicine > Institute of Physiology
07 Faculty of Science > Institute of Physiology
Dewey Decimal Classification:570 Life sciences; biology
Deposited On:11 Feb 2008 12:22
Last Modified:05 Apr 2016 12:18
Publisher:American Association for Cancer Research
Publisher DOI:10.1158/0008-5472.CAN-05-1877
PubMed ID:16322259

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