Notch1 ablation radiosensitizes glioblastoma cells
Na Han1, Guangyuan Hu1, Lei Shi1
1Department of Oncology, Tongji Hospital, Tongji Medical College, Huazhong University of Science & Technology, Wuhan, China.
Abstract:
Broad specific Notch1 inhibitors suppress glioblastoma multiforme (GBM) growth but have significant gastrointestinal toxicities. Here, we examined Notch1 expression in GBM tissue specimens and its correlation with the overall survival (OS) of GBM patients. Furthermore, using the CRISPR/Cas9 system, we investigated the effects of Notch1 downregulation on clonogenic growth and angiogenesis of GBM cells and xenografts. Immunohistochemistry showed positive Notch1 expression in 71% (49/69) of GBM tissues. Our multivariate Cox regression analysis further revealed that Notch1 expression was an independent adverse prognostic factor for OS. Notch1 downregulation suppressed the growth of GBM cells U87MG and U251. The mean duration to reach 6 x the starting volume was 18.3 days for xenografts with Notch1 downregulation and 13.4 days for the control xenografts. Immunofluorescent staining further disclosed that Notch1 downregulation markedly increased the number of γH2AX foci and radiosensitized GBM cells. Notch1 downregulation also impaired angiogenesis and attenuated VEGF and hypoxic response to irradiation in xenografts. In conclusion, Notch1 ablation inhibited GBM cell proliferation and neovascularization and radiosensitized GBM cells and xenografts, suggesting a pivotal role of Notch1 in tumor growth, angiogenesis, and radioresistance in GBM.
Insights
Notch1 promotes glioblastoma growth and resistance to radiation. Inhibiting Notch1 in glioblastoma (GBM) suppressed tumor growth, impaired blood vessel formation, and enhanced radiosensitivity.
Area of Science:
- Oncology
- Molecular Biology
- Genetics
Background:
- Notch1 signaling is implicated in glioblastoma (GBM) pathogenesis.
- Targeting Notch1 presents a therapeutic strategy for GBM, but broad inhibitors cause toxicity.
Purpose of the Study:
- To investigate Notch1 expression in GBM tissues and its prognostic value.
- To evaluate the therapeutic potential of Notch1 downregulation in GBM using CRISPR/Cas9.
Main Methods:
- Immunohistochemistry to assess Notch1 expression in GBM tissues.
- CRISPR/Cas9 to downregulate Notch1 in GBM cell lines and xenografts.
- Assessment of cell proliferation, clonogenic growth, angiogenesis, and radiosensitivity.
Main Results:
- Positive Notch1 expression was observed in 71% of GBM tissues and correlated with poorer overall survival.
- Notch1 downregulation inhibited GBM cell proliferation and xenograft growth.
- Notch1 downregulation increased radiosensitivity, impaired angiogenesis, and reduced VEGF levels.
Conclusions:
- Notch1 is an adverse prognostic factor and a therapeutic target in GBM.
- Notch1 downregulation inhibits GBM proliferation and angiogenesis, and enhances radiosensitivity.
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