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Tumor Biology |
Imperial Cancer Research Fund Molecular Oncology Laboratory and Angiogenesis Group, Institute of Molecular Medicine, John Radcliffe Hospital, Oxford OX3 9DU [K. J. T., J. W. M., A. J., C. H., A. L. H.]; Imperial Cancer Research Fund Mutation Detection Facility, Ashley Wing, St. James’s University Hospital, Leeds LS9 7TF [C. F. T., D. C-H.]; Nuffield Department of Cellular Science and Clinical Biochemistry, John Radcliffe Hospital, Oxford OX3 9DU [R. D. L., K. C. G.]; Wellcome Trust Centre for Human Genetics, Oxford OX3 7BN [P. H. M., P. J. R.]; and Department of Urology, Churchill Hospital, Oxford OX3 7LJ [D. C.], United Kingdom
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ABSTRACT |
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 Top ABSTRACT INTRODUCTIONMATERIALS AND METHODSRESULTSDISCUSSIONREFERENCES |
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subunits for proteolysis. Stabilization of HIF- subunits has been described in VHL-defective cell lines, leading to HIF activation and up-regulation of hypoxia-inducible mRNAs. Mutations of the von Hippel-Lindau tumor suppressor protein are found in most clear cell renal cell carcinomas (CC-RCCs) but not other renal tumors, raising a question about the importance of activation of the HIF pathway in CC-RCC development. To address this question, we have examined the expression of HIF- subunits in 45 primary renal tumors and related this to tumor subtype, the presence of VHL mutations, and measures of angiogenesis. We show that HIF- is up-regulated in the majority of CC-RCCs, and that the pattern of expression is biased toward the HIF-2 isoform. Expression of HIF- proteins was associated significantly with up-regulation of VEGF mRNA and protein and increased microvessel density. Up-regulation of HIF- in CC-RCC was found to involve increased mRNA as well as protein expression, suggesting that both VHL-dependent and VHL-independent mechanisms are involved. These results suggest that activation of the HIF pathway is functionally important in CC-RCC development and might provide a new therapeutic target. |
INTRODUCTION |
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TopABSTRACTINTRODUCTIONMATERIALS AND METHODSRESULTSDISCUSSIONREFERENCES |
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and HIF-1ß/ARNT (4)
. In the presence of oxygen, HIF-1 protein is destroyed rapidly by the proteasome so that steady-state levels are low (5)
. In hypoxia, this process is suppressed, allowing activation of the transcriptional response. HIF-2 also dimerises with HIF-1ß/ARNT and is functionally and structurally similar to HIF-1 (6
, 7)
.
In cancer, the HIF system can be activated by microenvironmental hypoxia; this response appears to be amplified by a variety of oncogenic mechanisms (8)
. Clear insight into these processes has been provided by studies of the pVHL. pVHL functions as the recognition component of a multicomponent ubiquitin ligase that targets specific sequences in HIF- subunits (9, 10, 11, 12)
.
Individuals with VHL syndrome have a high lifetime risk of developing CC-RCC. In sporadic CC-RCCs (which account for 85% of renal cancers), the VHL gene is mutated in 50–60% of cases (13) and silenced by hypermethylation in an additional 15% (14) . VHL mutations are not found in association with other subtypes of renal cancer such as papillary, chromophobe, and collecting duct carcinomas and the essentially benign oncocytomas (15) .
These observations raise questions about the frequency of HIF- up-regulation in CC-RCC versus other tumor types and its relation to the oncogenic process. We have investigated the expression of HIF- in a series of human renal cancers and related the expression of HIF- to parameters of angiogenesis. We show that up-regulation of HIF-, particularly HIF-2, is a common and striking feature of CC-RCC, and that HIF- up-regulation in CC-RCC is correlated with enhanced VEGF expression and increased MVD.
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MATERIALS AND METHODS |
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TopABSTRACTINTRODUCTIONMATERIALS AND METHODSRESULTSDISCUSSIONREFERENCES |
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200 mg of tissue using TRI reagent (Sigma-Aldrich, Gillingham, Dorset, United Kingdom). RNase protection assays were performed in duplicate on 10–30 µg of total RNA as described (16)
. Labeled riboprobes for VEGF, HIF-1 (accession no. U224311), and HIF-2 (U81984) were prepared using [32P]CTP. To attenuate the signal strength of the highly abundant loading control U6 small nuclear RNA (accession no. X01366), a riboprobe of significantly lower specific activity was prepared by addition of unlabeled CTP to the labeling reaction.
The protected fragment size for VEGF121 was 517 nucleotides and for VEGF165 and VEGF189 was 439 nucleotides. Those for HIF-1, HIF-2, and the loading control were 253, 210, and 106 nucleotides, respectively. In each assay, a positive and negative (tRNA only) control and undigested riboprobes were analyzed. Intensity of signal, quantified on a PhosphorImager (Molecular Dynamics, Chesham, Buckinghamshire, United Kingdom) was calculated as the signal of interest:U6 signal ratio to account for minor loading differences. To allow comparison between samples, signal intensity for tissue samples was standardized against the positive control. The fold induction was determined by calculating the signal in the tumor:signal in paired normal tissue ratio, having previously adjusted for loading differences by comparison with the U6 control.
Protein Extraction and Immunoblot Analysis.
Frozen tumor samples were homogenized in extraction buffer [8 M urea, 10% glycerol, 10 mM Tris-HCl (pH 6.8), 1% SDS, 5 mM DTT, 0.5 mM phenylmethylsulfonyl, 1 µg/ml aprotinin, 10 µg/ml pepstatin, and 10 µg/ml leupeptin] using an IKA Ultra-Turrax T8 homogenizer (Janke & Kunkel and Co.) for 15 s at full speed. Extracts were quantified using the BCA protein assay (Pierce). Immunoblotting was performed as described (17)
.
Measurement of VEGF Protein in Tumor Samples.
Tumor protein extracts were prepared and analyzed using the Quantikine ELISA kit (R&D Systems Ltd., Abingdon, Oxfordshire, United Kingdom) as described (18)
.
Detection of VHL Mutations.
VHL genomic DNA sequence GenBank reference AF010238 was used as a reference sequence throughout.
PCR.
PCR was carried out using Amplitaq Gold (PE Biosystems, Warrington, Cheshire, United Kingdom). Four sense/antisense primer pairs were used (exon 1a, exon 1b, exon 2, and exon 3). Details of primers and reaction conditions are available on request. For fluorescent single-strand conformation polymorphism, primers were labeled with HEX and 6-carboxyfluorescein; unlabelled primers were used for denaturing high-performance liquid chromatography.
Mutation Detection.
Denaturing high-performance liquid chromatography and fluorescent single-strand conformation polymorphism analyses were as described (19)
, the latter using 49:1 acrylamide gels at 18°C. Mutations were confirmed by DNA sequencing using BigDye terminator chemistry (PE Biosystems, Warrington, Cheshire, United Kingdom; manufacturer’s protocol), with the addition of halfBD sequencing reagent (Genpak Ltd., New Milton, Hampshire, United Kingdom).
Immunohistochemistry.
Sections (4 µm) were floated on to X-Tra slides (Surgipath Europe Ltd.). Slides were dewaxed and rehydrated before antigen retrieval by pressure cooking for 3 min in Tris/EDTA buffer (pH 9.0). After incubation with 1:100 monoclonal antibody QBEnd10 (Dako) in TBS for 1 h, slides were incubated with goat antimouse IgG (Dako) for 30 min and then with alkaline phosphatase anti-alkaline phosphatase (Dako) for 30 min. The last two steps were repeated twice with 10-min incubations. New Fuchsin Red substrate (Dako) was applied for 15 min, and slides were counterstained with hematoxylin before mounting (Aquamount). MVD was determined by Chalkley vessel counting as described (20)
. The mean of the three Chalkley counts was then calculated to give the MVD score.
Statistics.
All tests were performed using the Stata package release 5 (Stata Corporation). Tests used were the K-W and M-W nonparametric tests, the t test, and ANOVA. In the analysis of the MVD data, scores were grouped into <7 and 
7.
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RESULTS |
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TopABSTRACTINTRODUCTIONMATERIALS AND METHODSRESULTSDISCUSSIONREFERENCES |
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. Tumor staging was performed in accordance with the 1997 joint International Union Against Cancer (UICC) and American Joint Commission on Cancer staging system (21)
. Tumors were classified according to the Heidelberg classification (15)
.
VHL Mutational Analysis.
To characterize further our series of CC-RCCs, we analyzed a subset for VHL mutations. Mutations were detected in 15 of 27 (56%) clear cell cases analyzed for mutation (data not shown). One tumor was from a patient with clinically verified VHL syndrome. No point mutations were found in this tumor, but our analysis would not have detected large deletions of the VHL gene, which account for a substantial proportion of VHL kindreds (22)
. For the same reason, or through hypermethylation, cases in which we sought but did not identify VHL mutations might have had functional silencing of VHL.
Expression of HIF-1 and HIF-2 Protein.
HIF-1 and HIF-2 protein expression was determined by immunoblotting in every case (Fig. 1
; Table 1
). HIF-1 was detected in the majority of CC-RCCs (26 of 34; 77%). HIF-2 expression was detected in CC-RCCs alone (27 of 34 cases; 79%). In all 35 cases where paired normal tissue was available, expression of HIF-1/HIF-2 in normal tissue was either absent or negligible in comparison to the corresponding tumor tissue. Of the CC-RCC cases, 22 of 34 (65%) expressed both factors, 4 of 34 (12%) expressed HIF-1 alone, 5 of 34 (15%) expressed HIF-2 alone, and 3 of 34 (9%) expressed neither factor. Of the cases known to be VHL defective, 11 of 16 (69%) expressed HIF-1, and 15 of 16 (94%) expressed HIF-2. In the cases where mutations were sought but not found (12 of 27), the frequency of HIF-1 expression was similar (9 of 12; 75%), but fewer cases expressed HIF-2 (6 of 12; 50%).
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and HIF-2 mRNA. and HIF-2 mRNA was assessed by RNase protection in 25 cases (Table 2
; Fig. 1
). Expression of HIF-1 mRNA in the tumor was greater than in paired normal tissue in 12 of 17 CC-RCCs and in 4 of 4 papillary tumors, 2 of 3 chromophobe tumors, and 1 of 1 collecting duct tumors. For HIF-1 mRNA, the difference between tumor and paired normal tissue was not statistically significant [P = 0.08, paired t test; mean (SD) RNA expression in tumors = 0.26 (0.17); mean (SD) RNA expression in paired normal tissue = 0.16 (0.18)]. Expression of HIF-2 mRNA was greater in tumor than in paired normal tissue in 17 of 17 CC-RCCs and in 1 of 3 chromophobe tumors but in no other tumors. For HIF-2 mRNA, there was a significant difference between tumor and paired normal tissue [P < 0.001, paired t test; mean (SD) RNA expression in tumors = 0.58 (0.44); mean (SD) RNA expression in paired normal tissue = 0.23 (0.13)]. The up-regulation of HIF-1 mRNA was not significantly greater in cases that expressed HIF-1 protein compared with those that did not [P = 0.7, M-W; cases that expressed HIF-1 protein, n = 14, mean RNA expression (SD) = 10.5 (14.8); cases that did not express HIF-1 protein, n = 11, mean RNA expression (SD) = 5.5 (6.2)]. However, the relationship was significant for HIF-2 with 5-fold greater up-regulation in tumors positive for HIF-2 protein expression [P < 0.001, M-W; cases that expressed HIF-2 protein, n = 15, mean RNA expression (SD) = 5.6 (5.9); cases that did not express HIF-2 protein, n = 10, mean RNA expression (SD) = 1.0 (0.7)].
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/2 to Angiogenesis. nor HIF-2 ("neither" group), those that expressed one factor but not the other ("either" group), and those that expressed both factors ("both" group). These three categories were used to assess the relationship between the expression of HIF- proteins and parameters of angiogenesis (Fig. 2)
. We examined the relationship between expression of HIF-1 proteins and tumor MVD. This relationship was examined in 31 of 34 CC-RCCs and in all non-clear cell tumors (Table 1
; Fig. 2
). CC-RCCs had a significantly higher MVD than non-clear cell tumors (P < 0.001, t test). In the series as a whole, there was a significant association between high MVD and expression of HIF- proteins [P < 0.001, ANOVA; "neither" group, n = 11, mean (SD) = 6.4 (2.9); "either" group, n = 12, mean (SD) = 10.8 (3.6); "both" group, n = 19, mean (SD) = 11.9 (3.1)].
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; Fig. 2
). VEGF protein was significantly higher in CC-RCCs than in non-clear cell tumors (P = 0.002, M-W), and in the series as a whole there was a significant relationship between VEGF expression and MVD (P = 0.01, M-W). Furthermore, in the series as a whole, there was a significant relationship between expression of HIF- proteins and increased VEGF [P = 0.002, K-W; "neither" group, n = 11, mean (SD) = 97 (226); "either" group, n = 12, mean (SD) = 910 (1040); "both" group, n = 19, mean (SD) = 1304 (1573)]. This relationship was also significant for CC-RCCs alone [P = 0.05, K-W; "neither" group, n = 3, mean (SD) = 8.3 (14)
; "either" group, n = 9, mean (SD) = 1170 (1087); "both" group, n = 19, mean (SD) = 1304 (1573)].
Because any effect of HIF- protein expression on VEGF is likely to be mediated, at least in part, at the transcriptional level, VEGF mRNA expression was determined in 25 cases, representing the same subset in which we had assayed HIF- mRNA (Table 1
; Fig. 2
). Expression of VEGF mRNA was significantly higher in CC-RCCs than in tumors of other types (P = <0.001, t test), although expression in the paired normal tissue did not differ between the two groups (P = 0.81, t test). Furthermore, in these 25 cases, fold up-regulation of VEGF mRNA in the tumor was significantly related to expression of HIF- protein [P = 0.001 K-W; "neither" group, n = 7, mean (SD) = 1.5 (1.7); "either" group, n = 7, mean (SD) = 7 (5)
; "both" group, n = 11, mean (SD) = 24 (30)
].
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DISCUSSION |
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TopABSTRACTINTRODUCTIONMATERIALS AND METHODSRESULTSDISCUSSIONREFERENCES |
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proteins in human renal tumors. We show that HIF-1 expression is up-regulated strongly in the majority of CC-RCCs in comparison with normal kidney, where expression was negligible or absent. This result contrasted with the findings in renal tumors of other types where strong HIF-1 up-regulation was much less frequent. For HIF-2, the contrast between tumor types was even greater. HIF-2 expression was commonly and strikingly up-regulated in CC-RCCs but was below the threshold of detection in renal tumors of other types.
Recent studies have established that pVHL acts as the substrate recognition component of a ubiquitin ligase that targets HIF- proteins for ubiquitin-mediated proteolysis (9
, 10
, 12)
. Furthermore, HIF- subunits are stabilized in VHL-defective cell lines, resulting in constitutive activation of the HIF transcriptional response (23)
. The VHL gene is mutated or silenced by hypermethylation in the majority of CC-RCCs (13
, 14)
. This raises a question about the importance of HIF activation in CC-RCC development. We and others have previously assayed a range of tumor-associated pVHL mutations for their ability to restore normal regulation of HIF-1 to pVHL-defective tissue culture cell lines (9
, 12)
. Thus far, all pVHL mutations associated with CC-RCC have been found to be defective in these assays. To pursue this, we have now assayed HIF- expression in primary renal tumors. Our finding that most CC-RCCs manifest striking up-regulation of HIF- subunits extends the findings in tissue culture cell lines (24)
and is consistent with a major role for HIF activation in CC-RCC oncogenesis.
Nevertheless, up-regulation of both HIF- subunits was not always observed across the series of tumors. Because some CC-RCC lines (for instance CAKI-1) are wild type for VHL and show normal regulation of HIF- (23)
, we considered whether tumors that did not express high levels of HIF- proteins might form a subgroup of CC-RCCs that were wild type for VHL. However, even when the analysis was confined to cases in which a VHL mutation was proven, up-regulation of both HIF- subunits was not universal. Feasibly some pVHL mutations could differentially affect regulation of one or other HIF- subunit, but we have not observed this with different mutated pVHLs in transfection assays (9)
. Most probably, HIF- subunit expression is subject to other controls that determine the extent to which HIF-1 or HIF-2 accumulation occurs when pVHL-dependent proteolysis is disabled.
This possibility is supported strongly by the analysis of HIF-1 and HIF-2 mRNA levels, which showed striking up-regulation in many tumors when compared with normal kidney. This observation is supported by the results of another study that used reverse transcription-PCR (25)
. In VHL-defective cell lines, we found previously that restoration of wild-type pVHL did not self-regulate the mRNA of either HIF- subunit, suggesting that up-regulation of HIF- mRNAs in CC-RCC is not a direct consequence of the VHL defect itself (23)
. In contrast, others authors found that reintroduction of a wild-type VHL gene into a VHL-deficient RCC cell line resulted in up-regulation of HIF-1 mRNA but self-regulation of HIF-2 mRNA (24)
. Overall, the mechanisms regulating HIF- mRNA levels are still largely unclear.
Also of interest was the pattern of HIF- subunit expression. In CC-RCCs, expression of HIF- subunits was biased toward HIF-2. When the analysis was confined to CC-RCCs with a proven VHL mutation, HIF-2 up-regulation was particularly frequent, being observed in 94% of cases versus none of the non-CC-RCC tumors. This bias was seen both at the protein and mRNA level. A similar bias has been observed in analyses of VHL-defective cell lines (23
, 24)
. Moreover, the same shift toward HIF-2 mRNA expression has been observed in CNS hemangioblastomas, another VHL-associated tumor where VHL inactivation is common not only in familial but also in sporadic cases (26)
. In these tumors, HIF-2 (but not HIF-1) mRNA was strikingly elevated in comparison with normal tissue and correlated with up-regulation of VEGF mRNA. Taken together, these findings suggest that the shift toward HIF-2 subunit expression is somehow important in promoting VHL-associated oncogenesis. Conceivably, this may be attributable to differences in the range of target genes of HIF-2 relative to HIF-1. Studies of HIF target genes have defined examples with putative antitumorigenic properties, suggesting that it is the overall balance of target gene activation that determines the outcome of HIF activation (27)
. Although the determinants of target gene specificity have not been identified, forced expression studies have indicated that HIF-2 is relatively more active on the promoters of VEGF and the angiopoietin receptor, Tie-2, suggesting a particular role in the regulation of angiogenesis (6
, 7)
.
Tumor growth and the development of metastases are dependent upon angiogenesis. Furthermore, measures of angiogenesis are prognostic in many tumor types. The role of HIF in the regulation of VEGF therefore provides a potential link between HIF activation and the promotion of tumor growth. In support of this, tumor xenografts from HIF-1ß-deficient hepatomas were found to be less well vascularized than their wild-type counterparts (28)
. Surprisingly, experimental studies of HIF--deficient cells have revealed conflicting data with one study of HIF-1 -/- embryonic stem cells demonstrating reduced vascularization and a different study of HIF-1 -/- fibroblasts reporting no effect on vascularization (29
, 30)
. The link between HIF and tumor vascularization may depend on the cell background or on the mode and extent of HIF inactivation. Here we observed that up-regulation of HIF- is associated with significantly higher vascular density in human renal tumors. The significant associations between the expression of HIF- subunits and that of VEGF mRNA/protein suggest a functional role for HIF in enhancing expression of VEGF and ultimately angiogenesis. Two studies published during the course of this work support this possibility. Semiquantitative immunochemistry was used to show an association between vascularization and HIF-1 expression in human gliomas (31)
, and in situ hybridization was used to show concordance in the distribution of HIF-2 and VEGF mRNA in a study limited to 13 RCCs (25)
.
HIF-1 protein expression in renal tumors was investigated in another recent study (32)
. HIF-1 protein was expressed in 24 of 32 (75%) of CC-RCCs, which is virtually identical to our findings. That study also indicated associations between VHL loss of function and induction of HIF-1 and between induction of HIF-1 and expression of target genes. However, Wiesener et al. (32)
did not evaluate expression of HIF-2. The differences observed here between the two factors suggest that the HIF-2 pathway is particularly significant in RCC. Furthermore, unlike Wiesener et al. (32)
, we found up-regulation of HIF- mRNA in the majority of tumors. Although this up-regulation was not significant for HIF-1, it was highly significant for HIF-2.
Our findings demonstrate that up-regulation of the HIF system is common in CC-RCC, and they support the hypothesis that mutations of pVHL promote CC-RCC development by disabling regulation of HIF- subunits. Concurrent up-regulation of HIF- subunit mRNAs in CC-RCC suggests additional mechanisms contributing to HIF activation and is consistent with a functional role for HIF in CC-RCC development. Growth of experimental tumors derived from breast and colon cancer cell lines is suppressed by antagonism of HIF activation (33)
. Our work suggests that CC-RCC may be a particularly good target for this new approach to therapy.
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FOOTNOTES |
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1 Supported in part by a Royal College of Surgeons of England Research Fellowship (to K. J. T.) and by the Imperial Cancer Research Fund. 
2 To whom requests for reprints should be addressed, at University of Oxford, Institute of Molecular Medicine, John Radcliffe Hospital, Oxford OX3 9DU, United Kingdom. Phone: 44-1865-222457; Fax: 44-1865-222431; E-mail: aharris.lab{at}icrf.icnet.uk
3 The abbreviations used are: VEGF, vascular endothelial growth factor; HIF, hypoxia-inducible factor; VHL, von Hippel-Lindau; pVHL, VHL tumor suppressor protein; CC-RCC, clear cell renal cell carcinoma; MVD, microvessel density; K-W, Kruskal-Wallis; M-W, Mann-Whitney.
Received 8/30/01. Accepted 3/18/02.
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REFERENCES |
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TopABSTRACTINTRODUCTIONMATERIALS AND METHODSRESULTSDISCUSSIONREFERENCES |
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is mediated by an oxygen-dependent domain via the ubiquitin-proteasome pathway. Proc. Natl. Acad. Sci. USA, 95: 7987-7992, 1998.. Blood, 92: 2260-2268, 1998. binding and ubiquitylation by the von Hippel-Lindau tumor suppressor protein. J. Biol. Chem., 275: 25733-25741, 2000. ubiquitination by a reconstituted von Hippel-Lindau (VHL) tumor suppressor complex. Proc. Natl. Acad. Sci. USA, 97: 10430-10435, 2000. by the von Hippel-Lindau tumor suppressor protein. EMBO J., 19: 4298-4309, 2000.[Medline]
and HIF-2 in normal human tissues, cancers, and tumour associated macrophages. Am. J. Pathol., 157: 411-421, 2000. and HIF-2 under normoxic conditions in renal carcinoma cells by von Hippel-Lindau tumor suppressor gene loss of function. Oncogene, 19: 5435-5443, 2000.[Medline]
. Am. J. Pathol., 153: 25-29, 1998. in hypoxia-mediated apoptosis, cell proliferation and tumour angiogenesis. Nature (Lond.), 394: 485-490, 1998.[Medline]
is a positive factor in solid tumor growth. Cancer Res., 60: 4010-4015, 2000. in brain tumors: association with angiogenesis, invasion, and prognosis. Cancer (Phila.), 88: 2606-2618, 2000.[Medline]
in clear cell renal carcinomas. Cancer Res., 61: 5215-5222, 2001.This article has been cited by other articles:
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  M. R. M. Sun, L. Ngo, E. M. Genega, M. B. Atkins, M. E. Finn, N. M. Rofsky, and I. Pedrosa Renal Cell Carcinoma: Dynamic Contrast-enhanced MR Imaging for Differentiation of Tumor Subtypes--Correlation with Pathologic Findings Radiology, March 1, 2009; 250(3): 793 - 802. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
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|
 |
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|
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|
 |
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|
 |
|
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|
|
|
|
 |
|
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|
|
|
|
|
|
T. Shinojima, M. Oya, A. Takayanagi, R. Mizuno, N. Shimizu, and M. Murai Renal cancer cells lacking hypoxia inducible factor (HIF)-1{alpha} expression maintain vascular endothelial growth factor expression through HIF-2{alpha} Carcinogenesis, March 1, 2007; 28(3): 529 - 536. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
B. I. Rini Vascular Endothelial Growth Factor-Targeted Therapy in Renal Cell Carcinoma: Current Status and Future Directions Clin. Cancer Res., February 15, 2007; 13(4): 1098 - 1106. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
D. Cho, S. Signoretti, M. Regan, J. W. Mier, and M. B. Atkins The Role of Mammalian Target of Rapamycin Inhibitors in the Treatment of Advanced Renal Cancer Clin. Cancer Res., January 15, 2007; 13(2): 758s - 763s. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
J. An and M. B. Rettig Epidermal growth factor receptor inhibition sensitizes renal cell carcinoma cells to the cytotoxic effects of bortezomib Mol. Cancer Ther., January 1, 2007; 6(1): 61 - 69. [Abstract] [Full Text] [PDF]
|
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|
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|
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|
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|
|
 |
|
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|
|
|
|
 |
|
 V. H. Haase Hypoxia-inducible factors in the kidney Am J Physiol Renal Physiol, August 1, 2006; 291(2): F271 - F281. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
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|
|
|
|
 |
|
 J. An and M. B. Rettig Mechanism of von Hippel-Lindau Protein-Mediated Suppression of Nuclear Factor kappa B Activity Mol. Cell. Biol., September 1, 2005; 25(17): 7546 - 7556. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
A. Mani and E. P. Gelmann The Ubiquitin-Proteasome Pathway and Its Role in Cancer J. Clin. Oncol., July 20, 2005; 23(21): 4776 - 4789. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
D. Zagzag, B. Krishnamachary, H. Yee, H. Okuyama, L. Chiriboga, M. A. Ali, J. Melamed, and G. L. Semenza Stromal Cell-Derived Factor-1{alpha} and CXCR4 Expression in Hemangioblastoma and Clear Cell-Renal Cell Carcinoma: von Hippel-Lindau Loss-of-Function Induces Expression of a Ligand and Its Receptor Cancer Res., July 15, 2005; 65(14): 6178 - 6188. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
W. M. Stadler, G. Rosner, E. Small, D. Hollis, B. Rini, S. D. Zaentz, J. Mahoney, and M. J. Ratain Successful Implementation of the Randomized Discontinuation Trial Design: An Application to the Study of the Putative Antiangiogenic Agent Carboxyaminoimidazole in Renal Cell Carcinoma--CALGB 69901 J. Clin. Oncol., June 1, 2005; 23(16): 3726 - 3732. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
T. Ogushi, S. Takahashi, T. Takeuchi, T. Urano, K. Horie-Inoue, J. Kumagai, T. Kitamura, Y. Ouchi, M. Muramatsu, and S. Inoue Estrogen Receptor-Binding Fragment-Associated Antigen 9 Is a Tumor-Promoting and Prognostic Factor for Renal Cell Carcinoma Cancer Res., May 1, 2005; 65(9): 3700 - 3706. [Abstract] [Full Text] [PDF]
|
|
|
|
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|
B. I. Rini and E. J. Small Biology and Clinical Development of Vascular Endothelial Growth Factor-Targeted Therapy in Renal Cell Carcinoma J. Clin. Oncol., February 10, 2005; 23(5): 1028 - 1043. [Abstract] [Full Text] [PDF]
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A. Lidgren, Y. Hedberg, K. Grankvist, T. Rasmuson, J. Vasko, and B. Ljungberg The Expression of Hypoxia-Inducible Factor 1{alpha} Is a Favorable Independent Prognostic Factor in Renal Cell Carcinoma Clin. Cancer Res., February 1, 2005; 11(3): 1129 - 1135. [Abstract] [Full Text] [PDF]
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W. M. Stadler Therapeutic Options for Variant Renal Cancer: A True Orphan Disease Clin. Cancer Res., September 15, 2004; 10(18): 6393S - 6396S. [Abstract] [Full Text] [PDF]
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 M R Morris, E Maina, N V Morgan, D Gentle, D Astuti, H Moch, T Kishida, M Yao, P Schraml, F M Richards, et al. Molecular genetic analysis of FIH-1, FH, and SDHB candidate tumour suppressor genes in renal cell carcinoma J. Clin. Pathol., July 1, 2004; 57(7): 706 - 711. [Abstract] [Full Text] [PDF]
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S. Negrier, D. Perol, C. Menetrier-Caux, B. Escudier, M. Pallardy, A. Ravaud, J.-Y. Douillard, C. Chevreau, C. Lasset, and J.-Y. Blay Interleukin-6, Interleukin-10, and Vascular Endothelial Growth Factor in Metastatic Renal Cell Carcinoma: Prognostic Value of Interleukin-6--From the Groupe Francais d'Immunotherapie J. Clin. Oncol., June 15, 2004; 22(12): 2371 - 2378. [Abstract] [Full Text] [PDF]
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S. T. Palayoor, M. A. Burgos, A. Shoaibi, P. J. Tofilon, and C. N. Coleman Effect of Radiation and Ibuprofen on Normoxic Renal Carcinoma Cells Overexpressing Hypoxia-Inducible Factors by Loss of von Hippel-Lindau Tumor Suppressor Gene Function Clin. Cancer Res., June 15, 2004; 10(12): 4158 - 4164. [Abstract] [Full Text] [PDF]
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 V. R. Gordeuk, A. I. Sergueeva, G. Y. Miasnikova, D. Okhotin, Y. Voloshin, P. L. Choyke, J. A. Butman, K. Jedlickova, J. T. Prchal, and L. A. Polyakova Congenital disorder of oxygen sensing: association of the homozygous Chuvash polycythemia VHL mutation with thrombosis and vascular abnormalities but not tumors Blood, May 15, 2004; 103(10): 3924 - 3932. [Abstract] [Full Text] [PDF]
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B. Kaufman, O. Scharf, J. Arbeit, M. Ashcroft, J. M. Brown, R. K. Bruick, J. D. Chapman, S. M. Evans, A. J. Giaccia, A. L. Harris, et al. Proceedings of the Oxygen Homeostasis/Hypoxia Meeting Cancer Res., May 1, 2004; 64(9): 3350 - 3356. [Abstract] [Full Text] [PDF]
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G. Powis and L. Kirkpatrick Hypoxia inducible factor-1{alpha} as a cancer drug target Mol. Cancer Ther., May 1, 2004; 3(5): 647 - 654. [Abstract] [Full Text] [PDF]
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B. I. Rini, S. Halabi, J. Taylor, E. J. Small, and R. L. Schilsky Cancer and Leukemia Group B 90206: A Randomized Phase III Trial of Interferon-{alpha} or Interferon-{alpha} Plus Anti-Vascular Endothelial Growth Factor Antibody (Bevacizumab) in Metastatic Renal Cell Carcinoma Clin. Cancer Res., April 15, 2004; 10(8): 2584 - 2586. [Abstract] [Full Text] [PDF]
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 G. Hopfl, O. Ogunshola, and M. Gassmann HIFs and tumors--causes and consequences Am J Physiol Regulatory Integrative Comp Physiol, April 1, 2004; 286(4): R608 - R623. [Abstract] [Full Text] [PDF]
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M. B. Atkins, M. Hidalgo, W. M. Stadler, T. F. Logan, J. P. Dutcher, G. R. Hudes, Y. Park, S.-H. Liou, B. Marshall, J. P. Boni, et al. Randomized Phase II Study of Multiple Dose Levels of CCI-779, a Novel Mammalian Target of Rapamycin Kinase Inhibitor, in Patients With Advanced Refractory Renal Cell Carcinoma J. Clin. Oncol., March 1, 2004; 22(5): 909 - 918. [Abstract] [Full Text] [PDF]
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S. Welsh, R. Williams, L. Kirkpatrick, G. Paine-Murrieta, and G. Powis Antitumor activity and pharmacodynamic properties of PX-478, an inhibitor of hypoxia-inducible factor-1{alpha} Mol. Cancer Ther., March 1, 2004; 3(3): 233 - 244. [Abstract] [Full Text]
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E. Kleymenova, J. I. Everitt, L. Pluta, M. Portis, J. R. Gnarra, and C. L. Walker Susceptibility to vascular neoplasms but no increased susceptibility to renal carcinogenesis in Vhl knockout mice Carcinogenesis, March 1, 2004; 25(3): 309 - 315. [Abstract] [Full Text] [PDF]
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M. Hernberg, P. Virkkunen, P. Bono, H. Ahtinen, H. Maenpaa, and H. Joensuu Interferon Alfa-2b Three Times Daily and Thalidomide in the Treatment of Metastatic Renal Cell Carcinoma J. Clin. Oncol., October 15, 2003; 21(20): 3770 - 3776. [Abstract] [Full Text] [PDF]
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 J. C. Yang, L. Haworth, R. M. Sherry, P. Hwu, D. J. Schwartzentruber, S. L. Topalian, S. M. Steinberg, H. X. Chen, and S. A. Rosenberg A Randomized Trial of Bevacizumab, an Anti-Vascular Endothelial Growth Factor Antibody, for Metastatic Renal Cancer N. Engl. J. Med., July 31, 2003; 349(5): 427 - 434. [Abstract] [Full Text] [PDF]
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L. Zhang, N. Yang, D. Katsaros, W. Huang, J.-W. Park, S. Fracchioli, C. Vezzani, I. A. Rigault de la Longrais, W. Yao, S. C. Rubin, et al. The Oncogene Phosphatidylinositol 3'-Kinase Catalytic Subunit {alpha} Promotes Angiogenesis via Vascular Endothelial Growth Factor in Ovarian Carcinoma Cancer Res., July 15, 2003; 63(14): 4225 - 4231. [Abstract] [Full Text] [PDF]
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M. Y. Liu, L. Poellinger, and C. L. Walker Up-Regulation of Hypoxia-inducible Factor 2{alpha} in Renal Cell Carcinoma Associated with Loss of Tsc-2 Tumor Suppressor Gene Cancer Res., May 15, 2003; 63(10): 2675 - 2680. [Abstract] [Full Text] [PDF]
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S. J. Welsh, R. R. Williams, A. Birmingham, D. J. Newman, D. L. Kirkpatrick, and G. Powis The Thioredoxin Redox Inhibitors 1-Methylpropyl 2-Imidazolyl Disulfide and Pleurotin Inhibit Hypoxia-induced Factor 1{alpha} and Vascular Endothelial Growth Factor Formation Mol. Cancer Ther., March 1, 2003; 2(3): 235 - 243. [Abstract] [Full Text] [PDF]
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 E. Fox, G. A. Curt, and F. M. Balis Clinical Trial Design for Target-Based Therapy Oncologist, October 1, 2002; 7(5): 401 - 409. [Abstract] [Full Text] [PDF]
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) and non-clear cell tumors (
) are shown separately. Horizontal bars, median values.