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Updated: Jul 10, 2026
Comparing Metastatic Clear Cell Renal Cell Carcinoma Model Established in Mouse Kidney and on Chicken Chorioallantoic Membrane
Published on: February 8, 2020
Dominant-negative HIF-3 alpha 4 suppresses VHL-null renal cell carcinoma progression
Mindy A Maynard1, Andrew J Evans, Wei Shi
1Department of Laboratory Medicine and Pathobiology, University of Toronto, Toronto, Ontario, Canada.
Abstract:
The most prevalent mutations associated with the development of clear-cell renal cell carcinoma (CC-RCC) are the loss-of-function mutations of von Hippel-Lindau (VHL) tumor suppressor gene. These mutations invariably result in an inappropriate accumulation of HIF-alpha due to a failure of VHL as a substrate-recognition component of an E3 ubiquitin ligase complex to target HIFalpha for oxygen-dependent ubiquitin-mediated destruction. Stabilization of HIF-2alpha, but not HIF-1alpha, is the critical oncogenic event upon the functional loss of VHL in the development of CC-RCC. Here, we show that HIF-3alpha4, an alternatively spliced variant of human HIF-3alpha with similar domain structure as the murine inhibitory PAS protein (IPAS), forms an abortive transcriptional complex with HIF-2alpha and prevents the engagement of HIF-2 to the hypoxia-responsive elements (HREs) located in the promoter/ enhancer regions of hypoxia-inducible genes. In addition, the re-expression of HIF-3alpha4 in VHL-null 786-O CC-RCC cells via adenovirus decreases the endogenous expression of HIF-2-driven gene expression and suppresses the growth of 786-O tumor xenografts in SCID mice. These results suggest that HIF-3alpha4 is a naturally occurring dominant-negative HIF-3alpha splice isoform with tumor suppressive activity and support the targeted delivery of HIF-3alpha4 as a potential therapeutic option to curtail HIF-dependent tumor progression.
Insights
Loss-of-function mutations in the von Hippel-Lindau (VHL) gene drive clear-cell renal cell carcinoma (CC-RCC) by stabilizing HIF-2alpha. HIF-3alpha4 acts as a tumor suppressor by inhibiting HIF-2alpha activity in CC-RCC.
Area of Science:
- Oncology
- Molecular Biology
- Genetics
Background:
- Clear-cell renal cell carcinoma (CC-RCC) is primarily driven by loss-of-function mutations in the von Hippel-Lindau (VHL) tumor suppressor gene.
- VHL gene mutations lead to the accumulation of Hypoxia-Inducible Factor alpha (HIF-alpha) due to impaired degradation.
- Stabilization of HIF-2alpha, not HIF-1alpha, is crucial for CC-RCC development following VHL loss.
Purpose of the Study:
- To investigate the role of HIF-3alpha4, an alternative splice variant of HIF-3alpha, in CC-RCC pathogenesis.
- To determine if HIF-3alpha4 possesses tumor suppressive activity and could be a therapeutic target.
Main Methods:
- Investigated the interaction between HIF-3alpha4 and HIF-2alpha using in vitro assays.
- Utilized adenovirus-mediated gene delivery to re-express HIF-3alpha4 in VHL-null CC-RCC cells (786-O).
- Assessed the impact of HIF-3alpha4 re-expression on HIF-2-driven gene expression and tumor growth in SCID mouse xenografts.
Main Results:
- HIF-3alpha4 forms a transcriptional complex with HIF-2alpha, preventing its binding to hypoxia-responsive elements (HREs).
- Re-expression of HIF-3alpha4 in VHL-null CC-RCC cells reduced HIF-2-driven gene expression.
- HIF-3alpha4 re-expression suppressed the growth of 786-O tumor xenografts in vivo.
Conclusions:
- HIF-3alpha4 functions as a naturally occurring dominant-negative splice isoform of HIF-3alpha.
- HIF-3alpha4 exhibits tumor suppressive activity in CC-RCC by inhibiting HIF-2alpha.
- Targeted delivery of HIF-3alpha4 represents a potential therapeutic strategy for managing HIF-dependent tumor progression in CC-RCC.
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