Hsp90 Regulates a von Hippel Lindau-independent Hypoxia-inducible Factor-1α-degradative Pathway

Isaacs, Jennifer S.; Jung, Yunjin; Mimnaugh, Edward G.; Martı́nez, Alfredo; Cuttitta, Frank; Neckers, Leonard Μ.

doi:10.1074/jbc.m204733200

Cited by 627 publications

(487 citation statements)

References 66 publications

(48 reference statements)

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“…Adding GA to 6 h hypoxic treated prostate cells resulted in a decrease in HIF-1a protein levels in all the four cell lines. Isaacs et al 20 showed that the addition of GA promotes the degradation of HIF-1a under hypoxia rather than preventing HIF-1a upregulation. Our results show that neither hypoxia nor GA have any effect on HIF-1a mRNA levels.…”

Section: Inhibition Of Hif-1a By Geldanamycinmentioning

confidence: 99%

“…Hsp90 also cooperates with the proteasomal pathway to eliminate misfolded cellular proteins. 20,21 The antibiotic GA associates with Hsp90 and modulates its chaperone function by accelerating the degradative activity associated with Hsp90. 22,23 The ability of GA to promote the proteasome-dependent degradation of client proteins including HIF-1a provides it as a potential antitumor agent.…”

Section: Introductionmentioning

confidence: 99%

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Effects of geldanamycin on HIF-1α mediated angiogenesis and invasion in prostate cancer cells

Alqawi

Moghaddas

Singh

2006

Prostate Cancer Prostatic Dis

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Geldanamycin (GA), a benzoquinone ansamycin, is a naturally occurring inhibitor of heat shock protein (Hsp90), which regulates the transcription activity of hypoxia-inducible factor 1 (HIF-1a). Under hypoxia, HIF-1a is activated in tumor cells, and induces the transcription of vascular endothelial growth factor (VEGF), which is the prime regulator for angiogenesis. VEGF promotes the formation of new blood vessels by stimulating endothelial cell division and migration. This eventually forms a vascular network that allows for tumor growth and metastasis. In this study, we used GA to inhibit HIF-1a transcription function. Human prostate cancer DU-145 cells were incubated in a hypoxic chamber at 1% O 2 and 371C for different durations. Both mRNA and protein levels of HIF-1a and VEGF were upregulated under hypoxic conditions. We demonstrated that GA treatment of hypoxic DU-145 cells abolished the induction of HIF-1a protein in a time-dependent manner and decreased VEGF mRNA and its protein levels. The transient transfection of DU-145 cells with luciferase reporter gene construct (5HRE/hCMVmp-luc) showed that the transcriptional activity of HIF-1a was significantly induced in response to hypoxia, but inhibited by GA. In addition, using conditioned medium from GA-treated hypoxic cells led to a significant decrease in cell invasion in comparison with using conditioned medium from nontreated hypoxic cells. These data provide evidence for the important role of GA in inhibition of angiogenesis and also invasion mediated by HIF-1a in prostate cancer cells.

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Section: Inhibition Of Hif-1a By Geldanamycinmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Effects of geldanamycin on HIF-1α mediated angiogenesis and invasion in prostate cancer cells

Alqawi

Moghaddas

Singh

2006

Prostate Cancer Prostatic Dis

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Section: Introductionmentioning

confidence: 99%

“…The requirement of pVHL for HIF-1␣ degradation is underscored in cells that do not contain a functional pVHL, which leads to high levels of HIF-1␣ in normoxia (Maxwell et al, 1999;Krieg et al, 2000;Clifford et al, 2001). However, recently, a pVHL-and oxygen-independent HIF-1␣ degradation pathway has been reported (Isaacs et al, 2002).In normoxia HIF-1␣ is hydroxylated at Pro564 and Pro402, which is required for pVHL binding Jaakkola et al, 2001;Masson et al, 2001;Yu et al, 2001). Prolyl hydroxylation is performed by enzymes sharing homology with the EGL-9 protein from Caenorhabditis elegans (Epstein et al, 2001).…”

mentioning

confidence: 99%

Nitric Oxide Impairs Normoxic Degradation of HIF-1α by Inhibition of Prolyl Hydroxylases

Metzen

Zhou

Jelkmann

et al. 2003

MBoC

371

259

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Hypoxia inducible factor-1 (HIF-1) is the master regulator of metabolic adaptation to hypoxia. It is appreciated that HIF-1␣ accumulation is achieved under normoxic conditions by e.g., nitric oxide. We determined molecular mechanisms of HIF-1␣ accumulation under the impact of S-nitrosoglutathione (GSNO). In human embryonic kidney cells GSNO provoked nuclear accumulation of HIF-1␣. This appeared unrelated to gene transcription and protein translation, thus pointing to inhibition of HIF-1␣ degradation. Indeed, GSNO as well as the hypoxia mimic CoCl 2 decreased ubiquitination of HIF-1␣ and GSNO-induced HIF-1␣ failed to coimmunoprecipitate with pVHL (von Hippel Lindau protein). Considering that HIF-1␣-pVHL interactions require prolyl hydroxylation of HIF-1␣, we went on to demonstrate inhibition of HIF-1␣ prolyl hydroxylases (PHDs) by GSNO. In vitro HIF-1␣-pVHL interactions revealed that GSNO dose-dependently inhibits PHD activity but not the interaction of a synthetic peptide resembling the hydroxylated oxygen-dependent degradation domain of HIF-1␣ with pVHL. We conclude that GSNO-attenuated prolyl hydroxylase activity accounts for HIF-1␣ accumulation under conditions of NO formation during normoxia and that PHD activity is subject to regulation by NO. INTRODUCTIONThe heterodimeric transcription factor hypoxia inducible factor-1 (HIF-1) plays a central role in adaptation to decreased oxygen availability (Semenza, 2002;Wenger, 2002;Brü ne and Zhou, 2003). HIF-1 is composed of the two basic helix-loop-helix-Per-Arnt-Sim (bHLH-PAS) proteins HIF-1␣ and the aryl hydrocarbon receptor nuclear translocator (ARNT), also known as HIF-1␤ (Wang and Semenza, 1995). In many cell types, the mRNA of both HIF-1␣ and HIF-1␤ appear permanently expressed and HIF-1␤ protein is constitutively present. However, HIF-1␣ protein is kept at a low or undetectable level under normoxia. In hypoxia, HIF-1␣ is strikingly induced, translocates to the nucleus, and dimerizes with HIF-1␤ to form HIF-1, which binds to hypoxiaresponsive elements (HRE) in regulatory regions of an impressive array of target genes involved in angiogenesis, erythropoiesis, vasomotor control, and energy metabolism as well as in cell survival decisions (for references, see Maxwell et al., 2001;Wenger, 2002; Zhu et al., 2002). This makes HIF-1 the master regulator of oxygen homeostasis to meet cell and tissue requirements in a situation of oxygen deficiency.In normoxia HIF-1␣ is bound to the von Hippel Lindau protein (pVHL) (Maxwell et al., 1999;Hon et al., 2002;Min et al., 2002), which is the substrate recognizing component of an E3 ubiquitin ligase complex (Cockman et al., 2000;Ohh et al., 2000;Tanimoto et al., 2000). Consequently, HIF-1␣ is polyubiquitinated and degraded by the 26S proteasome system, thus accounting for its low normoxic level of expression (Salceda and Caro, 1997;Huang et al., 1998;Kallio et al., 1999). The requirement of pVHL for HIF-1␣ degradation is underscored in cells that do not contain a functional pVHL, which leads to high levels of HIF-1␣ in normox...

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“…Further experiments are needed to resolve why some cell lines arrest in G 1 -phase, whereas others do so in G 2 /M. Similarly, some studies report a degradation of HIF1a after Hsp90 inhibition (40), whereas others show merely a delayed accumulation of the protein (25) or an inhibition of the transcriptional activity (41). These differences may be explained by the individual study conditions and biological systems used.…”

Section: Discussionmentioning

confidence: 99%

Analysis of hypoxia‐inducible factor‐1α accumulation and cell cycle in geldanamycin‐treated human cervical carcinoma cells by laser scanning cytometry

2005

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Background: Tumor hypoxia has been linked to increased disease aggressiveness and poorer treatment outcomes, and the transcription factor hypoxia-inducible factor-1 (HIF-1) has been identified as the key molecule mediating the cellular response to hypoxic microenvironments. The a-subunit of this factor is accumulated under hypoxia and rapidly degraded during re-oxygenation, rendering the reliable measurement of HIF-1a a difficult task. Heat shock protein 90 (Hsp90) is an essential protein that controls the activity, turnover, and trafficking of a variety of other proteins including HIF-1a and cell cycle regulators. Hsp90 inhibitors like geldanamycin therefore have the potential to target tumor-cell survival by at least two mechanisms, compromising the accumulation of HIF-1a and cell proliferation. Methods: We describe here the simultaneous measurement of HIF-1a and cell cycle parameters by laser scanning cytometry (LSC) after exposure of two different

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Hsp90 Regulates a von Hippel Lindau-independent Hypoxia-inducible Factor-1α-degradative Pathway

Cited by 627 publications

References 66 publications

Effects of geldanamycin on HIF-1α mediated angiogenesis and invasion in prostate cancer cells

Effects of geldanamycin on HIF-1α mediated angiogenesis and invasion in prostate cancer cells

Nitric Oxide Impairs Normoxic Degradation of HIF-1α by Inhibition of Prolyl Hydroxylases

Analysis of hypoxia‐inducible factor‐1α accumulation and cell cycle in geldanamycin‐treated human cervical carcinoma cells by laser scanning cytometry

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