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Inhibition of HIF2alpha is sufficient to suppress pVHL-defective tumor growth.

Kondo K, Kim WY, Lechpammer M, Kaelin WG - PLoS Biol. (2003)

Bottom Line: Biallelic inactivation of the von Hippel-Lindau tumor suppressor gene (VHL) is linked to the development of hereditary (VHL-associated) and sporadic clear-cell renal carcinomas as well as other abnormalities.Conversely, downregulation of HIF2alpha with short hairpin RNAs is sufficient to suppress tumor formation by pVHL-defective renal carcinoma cells.These results establish that tumor suppression by pVHL is linked to regulation of HIF target genes.

View Article: PubMed Central - PubMed

Affiliation: Department of Adult Oncology, Dana-Farber Cancer Institute and Brigham and Womens Hospital, Harvard Medical School, Boston, Massachusetts, USA.

ABSTRACT
Biallelic inactivation of the von Hippel-Lindau tumor suppressor gene (VHL) is linked to the development of hereditary (VHL-associated) and sporadic clear-cell renal carcinomas as well as other abnormalities. The VHL gene product, pVHL, is part of an E3 ubiquitin ligase complex that targets the alpha subunits of the heterodimeric transcription factor HIF (hypoxia-inducible factor) for degradation in the presence of oxygen. Here we report that a HIF2alpha variant lacking both of its two prolyl hydroxylation/pVHL-binding sites prevents tumor inhibition by pVHL in a DNA-binding dependent manner. Conversely, downregulation of HIF2alpha with short hairpin RNAs is sufficient to suppress tumor formation by pVHL-defective renal carcinoma cells. These results establish that tumor suppression by pVHL is linked to regulation of HIF target genes.

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Tumor Suppression by HIF2α shRNA Is Not Restricted to a Single Cell Line(A) Tumor weights approximately 8 wk after subcutaneous implantation of A498 cells infected with the indicated retroviruses in nude mice. Number of tumors analyzed is shown in parentheses. Error bars = one standard error.(B) Representative histological sections after staining with hematoxylin and eosin of tumors formed by A498 cells infected with the indicated retroviruses.
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pbio.0000083-g004: Tumor Suppression by HIF2α shRNA Is Not Restricted to a Single Cell Line(A) Tumor weights approximately 8 wk after subcutaneous implantation of A498 cells infected with the indicated retroviruses in nude mice. Number of tumors analyzed is shown in parentheses. Error bars = one standard error.(B) Representative histological sections after staining with hematoxylin and eosin of tumors formed by A498 cells infected with the indicated retroviruses.

Mentions: To ask whether these findings could be extended to other VHL(−/−) renal carcinoma cell lines, we repeated these experiments in A498 VHL(−/−) renal carcinoma cells. Tumor formation by these cells in nude mice is diminished following restoration of pVHL function (Lonergan et al. 1998). In keeping with the results obtained with 786-O cells, downmodulation of HIF2α levels with shRNA did not affect A498 cell growth in vitro (data not shown), but dramatically inhibited tumor growth in vivo (Figure 4A). It is noteworthy that both 786-O cells and A498 cells produce HIF2α and not HIF1α (Maxwell et al. 1999). It will be important in the future to ask whether disruption of HIF2α is sufficient to suppress tumor formation by pVHL-defective cells that produce both HIFα paralogs. In this regard, studies of renal precursor lesions in VHL patients suggest that HIF2α is more oncogenic than HIF1α (Mandriota et al. 2002). It is tempting to speculate that loss of HIF1α expression in some pVHL-defective renal carcinoma cells confers a selective advantage in vivo, perhaps related to the ability of HIF1α to induce apoptosis in some settings (Carmeliet et al. 1998).


Inhibition of HIF2alpha is sufficient to suppress pVHL-defective tumor growth.

Kondo K, Kim WY, Lechpammer M, Kaelin WG - PLoS Biol. (2003)

Tumor Suppression by HIF2α shRNA Is Not Restricted to a Single Cell Line(A) Tumor weights approximately 8 wk after subcutaneous implantation of A498 cells infected with the indicated retroviruses in nude mice. Number of tumors analyzed is shown in parentheses. Error bars = one standard error.(B) Representative histological sections after staining with hematoxylin and eosin of tumors formed by A498 cells infected with the indicated retroviruses.
© Copyright Policy
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC300692&req=5

pbio.0000083-g004: Tumor Suppression by HIF2α shRNA Is Not Restricted to a Single Cell Line(A) Tumor weights approximately 8 wk after subcutaneous implantation of A498 cells infected with the indicated retroviruses in nude mice. Number of tumors analyzed is shown in parentheses. Error bars = one standard error.(B) Representative histological sections after staining with hematoxylin and eosin of tumors formed by A498 cells infected with the indicated retroviruses.
Mentions: To ask whether these findings could be extended to other VHL(−/−) renal carcinoma cell lines, we repeated these experiments in A498 VHL(−/−) renal carcinoma cells. Tumor formation by these cells in nude mice is diminished following restoration of pVHL function (Lonergan et al. 1998). In keeping with the results obtained with 786-O cells, downmodulation of HIF2α levels with shRNA did not affect A498 cell growth in vitro (data not shown), but dramatically inhibited tumor growth in vivo (Figure 4A). It is noteworthy that both 786-O cells and A498 cells produce HIF2α and not HIF1α (Maxwell et al. 1999). It will be important in the future to ask whether disruption of HIF2α is sufficient to suppress tumor formation by pVHL-defective cells that produce both HIFα paralogs. In this regard, studies of renal precursor lesions in VHL patients suggest that HIF2α is more oncogenic than HIF1α (Mandriota et al. 2002). It is tempting to speculate that loss of HIF1α expression in some pVHL-defective renal carcinoma cells confers a selective advantage in vivo, perhaps related to the ability of HIF1α to induce apoptosis in some settings (Carmeliet et al. 1998).

Bottom Line: Biallelic inactivation of the von Hippel-Lindau tumor suppressor gene (VHL) is linked to the development of hereditary (VHL-associated) and sporadic clear-cell renal carcinomas as well as other abnormalities.Conversely, downregulation of HIF2alpha with short hairpin RNAs is sufficient to suppress tumor formation by pVHL-defective renal carcinoma cells.These results establish that tumor suppression by pVHL is linked to regulation of HIF target genes.

View Article: PubMed Central - PubMed

Affiliation: Department of Adult Oncology, Dana-Farber Cancer Institute and Brigham and Womens Hospital, Harvard Medical School, Boston, Massachusetts, USA.

ABSTRACT
Biallelic inactivation of the von Hippel-Lindau tumor suppressor gene (VHL) is linked to the development of hereditary (VHL-associated) and sporadic clear-cell renal carcinomas as well as other abnormalities. The VHL gene product, pVHL, is part of an E3 ubiquitin ligase complex that targets the alpha subunits of the heterodimeric transcription factor HIF (hypoxia-inducible factor) for degradation in the presence of oxygen. Here we report that a HIF2alpha variant lacking both of its two prolyl hydroxylation/pVHL-binding sites prevents tumor inhibition by pVHL in a DNA-binding dependent manner. Conversely, downregulation of HIF2alpha with short hairpin RNAs is sufficient to suppress tumor formation by pVHL-defective renal carcinoma cells. These results establish that tumor suppression by pVHL is linked to regulation of HIF target genes.

Show MeSH
Related in: MedlinePlus