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Simultaneous targeting of Eph receptors in glioblastoma
Sara Ferluga1, Carla Maria Lema Tomé2, Denise Mazess Herpai1
1Department of Cancer Biology, Radiation Oncology and Neurosurgery, Brain Tumor Center of Excellence, Comprehensive Cancer Center of Wake Forest Baptist Medical Center, Wake Forest School of Medicine, Medical Center Boulevard, Winston-Salem, NC 27157, USA.
Abstract:
Eph tyrosine kinase receptors are frequently overexpressed and functional in many cancers, and they are attractive candidates for targeted therapy. Here, we analyzed the expression of Eph receptor A3, one of the most up-regulated factors in glioblastoma cells cultured under tumorsphere-forming conditions, together with EphA2 and EphB2 receptors. EphA3 was overexpressed in up to 60% of glioblastoma tumors tested, but not in normal brain. EphA3 was localized in scattered areas of the tumor, the invasive ring, and niches near tumor vessels. EphA3 co-localized with macrophage/leukocyte markers, suggesting EphA3 expression on tumor-infiltrating cells of bone marrow origin. We took advantage of the fact that ephrinA5 (eA5) is a ligand that binds EphA3, EphA2 and EphB2 receptors, and used it to construct a novel targeted anti-glioblastoma cytotoxin. The eA5-based cytotoxin potently and specifically killed glioblastoma cells with an IC50 of at least 10-11 M. This and similar cytotoxins will simultaneously target different compartments of glioblastoma tumors while mitigating tumor heterogeneity.
Insights
Eph receptor A3 is overexpressed in glioblastoma and can be targeted. A novel cytotoxin using ephrinA5 (eA5) effectively killed glioblastoma cells, offering a new therapeutic strategy.
Area of Science:
- Oncology
- Molecular Biology
- Neuroscience
Background:
- Eph tyrosine kinase receptors are implicated in cancer and are targets for therapy.
- Eph receptor A3 (EphA3) is significantly upregulated in glioblastoma, particularly in cells cultured under tumorsphere-forming conditions.
- EphA3 expression is detected in glioblastoma tumors but not in normal brain tissue.
Purpose of the Study:
- To analyze EphA3 expression in glioblastoma.
- To investigate the localization of EphA3 within glioblastoma tumors.
- To develop and evaluate a novel targeted cytotoxin for glioblastoma therapy.
Main Methods:
- Analysis of Eph receptor A3, EphA2, and EphB2 expression in glioblastoma.
- Immunohistochemical analysis of EphA3 localization in tumor tissues.
- Co-localization studies with macrophage/leukocyte markers.
- Construction of an ephrinA5 (eA5)-based cytotoxin targeting EphA3, EphA2, and EphB2 receptors.
Main Results:
- EphA3 overexpression was observed in up to 60% of glioblastoma tumors.
- EphA3 was found in tumor areas, the invasive ring, and near tumor vessels.
- EphA3 co-localized with immune cell markers, suggesting expression on infiltrating bone marrow-derived cells.
- The eA5-based cytotoxin demonstrated potent and specific killing of glioblastoma cells (IC50 ≥ 10-11 M).
Conclusions:
- EphA3 is a promising therapeutic target in glioblastoma.
- An eA5-based cytotoxin effectively targets glioblastoma cells.
- This targeted approach may address tumor heterogeneity and different tumor compartments.
