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Combined EphB2 receptor knockdown with radiation decreases cell viability and invasion in medulloblastoma
Shilpa Bhatia1, Kellen Hirsch1, Sanjana Bukkapatnam2
1Department of Radiation Oncology, University of Colorado Denver, Anschutz Medical Campus, 1665 Aurora Court Suite 1032, Aurora, CO 80045 USA.
Background:
Medulloblastoma is one of the most common types of pediatric brain tumor characterized by the subpopulation of cells that exhibit high invasive potential and radioresistant properties. In addition, dysregulated function and signaling by Eph family of receptors have been shown to impart pro-tumorigenic characteristics in this brain malignancy. In the current study, we investigated whether EphB2 knockdown in combination with radiation can alter invasiveness and decrease medulloblastoma tumor growth or viability in vitro.
Methods:
The expression of EphB2 receptor was analyzed by immunohistochemistry and Western blotting. Microarray analysis and mRNA analysis was performed on medulloblastoma patient datasets and compared to the normal cerebellum. The radiosensitization effect following EphB2 knockdown was determined by clonogenic assay in human medulloblastoma cells. Effects of EphB2-siRNA in absence or presence of radiation on cell cycle distribution, cell viability, and invasion were analyzed by flow cytometry, MTT assay, trypan blue exclusion assay, xcelligence system, and Western blotting.
Results:
We observed that EphB2 is expressed in both medulloblastoma cell lines and patient samples and its downregulation sensitized these cells to radiation as evident by decreased clonogenic survival fractions. EphB2 expression was also high across different medulloblastoma subgroups compared to normal cerebellum. The radiosensitization effect observed following EphB2 knockdown was in part mediated by enhanced G2/M cell cycle arrest. We also found that the combined approach of EphB2 knockdown and radiation exposure significantly reduced overall cell viability in medulloblastoma cells compared to control groups. Similar results were obtained in the xcelligence-based invasion assay. Western blot analysis also demonstrated changes in the protein expression of cell proliferation, cell survival, and invasion molecules in the combination group versus others.
Conclusions:
Overall, our findings indicate that specific targeting of EphB2 receptor in combination with radiation may serve as an effective therapeutic strategy in medulloblastoma. Future studies are warranted to test the efficacy of this approach in in vivo preclinical models.
Insights
Targeting EphB2 receptor in medulloblastoma with radiation therapy shows promise. This combination therapy reduced tumor cell viability and invasiveness, suggesting a potential new treatment strategy for this pediatric brain cancer.
Area of Science:
- Oncology
- Molecular Biology
- Genetics
Background:
- Medulloblastoma is a common pediatric brain tumor with invasive and radioresistant cells.
- Eph family receptor dysregulation contributes to medulloblastoma's aggressive nature.
- EphB2 receptor signaling is implicated in pro-tumorigenic characteristics.
Purpose of the Study:
- To investigate the combined effect of EphB2 knockdown and radiation on medulloblastoma.
- To determine if this combination alters invasiveness and reduces tumor growth or viability.
- To explore EphB2's role in medulloblastoma radioresistance.
Main Methods:
- Analyzed EphB2 expression via immunohistochemistry and Western blotting.
- Compared medulloblastoma patient data to normal cerebellum using microarray and mRNA analysis.
- Assessed radiosensitization using clonogenic assays, cell cycle analysis, viability assays (MTT, trypan blue), and invasion assays.
Main Results:
- EphB2 is highly expressed in medulloblastoma, and its downregulation sensitizes cells to radiation.
- Combined EphB2 knockdown and radiation significantly decreased cell viability and invasion.
- Radiosensitization was partly mediated by enhanced G2/M cell cycle arrest.
- Protein expression analysis revealed changes in proliferation, survival, and invasion molecules.
Conclusions:
- Targeting EphB2 with radiation is a potential therapeutic strategy for medulloblastoma.
- This combination approach effectively reduces medulloblastoma cell viability and invasiveness.
- Further in vivo preclinical studies are needed to validate this therapeutic strategy.