The role of aberrant VHL/HIF pathway elements in predicting clinical outcome to pazopanib therapy in patients with metastatic clear-cell renal cell carcinoma.

Inactivation of von Hippel-Lindau (VHL) gene in clear-cell renal cell carcinoma (RCC) leads to increased levels of hypoxia-inducible factors (HIF) and overexpression of HIF target genes, such as VEGF and others. VEGF-targeted agents are standard in advanced clear-cell RCC but biomarkers of activity are lacking. We analyzed tumor tissue samples from metastatic clear-cell RCC patients who received pazopanib as part of clinical trial VEG102616. We evaluated several components of the VHL/HIF pathway: VHL gene inactivation (mutation and/or methylation), HIF-1α and HIF-2α immunohistochemistry staining, and HIF-1α transcriptional signature. We evaluated the association of these biomarkers with best overall response rate (ORR) and progression-free survival (PFS) to pazopanib, a standard first-line VEGF-targeted agent. The VEG102616 trial enrolled 225 patients, from whom 78 samples were available for tumor DNA extraction. Of these, 70 patients had VHL mutation or methylation. VHL gene status did not correlate with ORR or PFS. Similarly, HIF-1α (65 samples) and HIF-2α (66 samples) protein levels (high vs. low) did not correlate with ORR or PFS to pazopanib. The HIF-1α transcriptional signature (46 samples) was enriched in tumors expressing high HIF-1α levels. However, the HIF-1α gene expression signature was not associated with clinical outcome to pazopanib. In patients with advanced clear-cell RCC, several potential biomarkers along the VHL/HIF-1α/HIF-2α axis were not found to be predictive for pazopanib activity. Additional efforts must continue to identify biomarkers associated with clinical outcome to VEGF-targeted agents in metastatic RCC.

Choueiri TK ，Fay AP ，Gagnon R ，Lin Y ，Bahamon B ，Brown V ，Rosenberg JE ，Hutson TE ，Baker-Neblett KL ，Carpenter C ，Liu Y ，Pandite L ，Signoretti S ... -  《-》

The relationship of erythropoietin overexpression with von Hippel-Lindau tumour suppressor gene mutations between hypoxia-inducible factor-1α and -2α in sporadic clear cell renal carcinoma.

Gong K ，Zhang N ，Zhang K ，Na Y ... -  《-》

Up-regulation of hypoxia-inducible factors HIF-1alpha and HIF-2alpha under normoxic conditions in renal carcinoma cells by von Hippel-Lindau tumor suppressor gene loss of function.

Hypoxia induces transcription of a range of physiologically important genes including erythropoietin and vascular endothelial growth factor. The transcriptional activation is mediated by the hypoxia-inducible factor-1 (HIF-1), a heterodimeric member of the basic helix-loop-helix PAS family, composed of alpha and beta subunits. HIF-1alpha shares 48 per cent identity with the recently identified HIF-2alpha protein that is also stimulated by hypoxia. In a previous study of hemangioblastomas, the most frequent manifestation of hereditary von Hippel-Lindau disease (VHL), we found elevated levels of vascular endothelial growth factor and HIF-2alpha mRNA in stromal cells of the tumors. Mutations of the VHL tumor suppressor gene are associated with a variety of tumors such as renal clear cell carcinomas (RCC). In this study, we analysed the expression of the hypoxia-inducible factors HIF-1alpha and HIF-2alpha in a range of VHL wildtype and VHL deficient RCC cell lines. In the presence of functional VHL protein, HIF-1alpha mRNA levels are elevated, whereas HIF-2alpha mRNA expression is increased only in cells lacking a functional VHL gene product. On the protein levels, however, in VHL deficient cell lines, both HIF-alpha subunits are constitutively expressed, whereas re-introduction of a functional VHL gene restores the instability of HIF-1alpha and HIF-2alpha proteins under normoxic conditions. Moreover, immunohistochemical analyses of RCCs and hemangioblastomas demonstrate up-regulation of HIF-1alpha and HIF-2alpha in the tumor cells. The data presented here provide evidence for a role of the VHL protein in regulation of angiogenesis and erythropoiesis mediated by the HIF-1alpha and HIF-2alpha proteins.

Krieg M ，Haas R ，Brauch H ，Acker T ，Flamme I ，Plate KH ... -  《ONCOGENE》

VHL and HIF-1α: gene variations and prognosis in early-stage clear cell renal cell carcinoma.

Lessi F ，Mazzanti CM ，Tomei S ，Di Cristofano C ，Minervini A ，Menicagli M ，Apollo A ，Masieri L ，Collecchi P ，Minervini R ，Carini M ，Bevilacqua G ... -  《-》

[The expression of hypoxia inducible factor-1,2 alpha in sporadic clear cell renal cell carcinoma and their relationships to the mutations of von Hippel-Lindau gene].

Gong K ，Zhang N ，Na X ，Wu G ，Yang XY ，Xin DQ ，Na YQ ... -  《-》