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Updated: Jul 15, 2025
Co-immunoprecipitation Assay Using Endogenous Nuclear Proteins from Cells Cultured Under Hypoxic Conditions
Published on: August 2, 2018
AXL is required for hypoxia-mediated hypoxia-inducible factor-1 alpha function in glioblastoma
Thuy-Trang T Vo1,2, Quangdon Tran1,2, Youngeun Hong1,2
1Department of Pharmacology, College of Medicine, Chungnam National University, Daejeon, 35015 Republic of Korea.
Abstract:
Glioblastoma (GBM) is the most aggressive type of central nervous system tumor. Molecular targeting may be important when developing efficient GBM treatment strategies. Sequencing of GBMs revealed that the receptor tyrosine kinase (RTK)/RAS/phosphatidylinositol-3-kinase pathway was altered in 88% of samples. Interestingly, AXL, a member of RTK, was proposed as a promising target in glioma therapy. However, the molecular mechanism of AXL modulation of GBM genesis and proliferation is still unclear. In this study, we investigated the expression and localization of hypoxia-inducible factor-1 alpha (HIF-1α) by AXL in GBM. Both AXL mRNA and protein are overexpressed in GBM. Short-interfering RNA knockdown of AXL in U251-MG cells reduced viability and migration. However, serum withdrawal reduced AXL expression, abolishing the effect on viability. AXL is also involved in hypoxia regulation. In hypoxic conditions, the reduction of AXL decreased the level and nuclear localization of HIF-1α. The co-expression of HIF-1α and AXL was found in human GBM samples but not normal tissue. This finding suggests a mechanism for GBM proliferation and indicates that targeting AXL may be a potential GBM therapeutic.
Supplementary Information:
The online version contains supplementary material available at 10.1007/s43188-023-00195-z.
Insights
AXL receptor tyrosine kinase (RTK) is overexpressed in glioblastoma (GBM) and drives tumor growth and migration. Targeting AXL may offer a new therapeutic strategy for GBM by impacting hypoxia-inducible factor-1 alpha (HIF-1α) signaling.
Area of Science:
- Neuro-oncology
- Molecular Biology
- Cancer Research
Background:
- Glioblastoma (GBM) is an aggressive brain tumor with high rates of pathway alterations.
- The receptor tyrosine kinase (RTK)/RAS/phosphatidylinositol-3-kinase pathway is frequently altered in GBM.
- AXL, an RTK, is a potential therapeutic target, but its role in GBM is not fully understood.
Purpose of the Study:
- To investigate the role of AXL in GBM proliferation and its relationship with hypoxia-inducible factor-1 alpha (HIF-1α).
- To explore AXL's expression, localization, and functional impact in GBM cells and tissues.
Main Methods:
- Short-interfering RNA (siRNA) knockdown of AXL in U251-MG GBM cells.
- Assessment of cell viability and migration.
- Analysis of AXL and HIF-1α expression and localization under normoxic and hypoxic conditions.
- Examination of co-expression in human GBM samples.
Main Results:
- AXL mRNA and protein are overexpressed in GBM.
- AXL knockdown reduced GBM cell viability and migration.
- AXL expression is linked to hypoxia regulation, affecting HIF-1α levels and nuclear localization.
- Co-expression of AXL and HIF-1α is observed in GBM but not normal tissues.
Conclusions:
- AXL plays a significant role in GBM proliferation and migration, potentially through modulation of HIF-1α.
- Targeting AXL presents a promising therapeutic strategy for glioblastoma.
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