Radiation-Induced Cellular Plasticity Primes Glioblastoma for Forskolin-Mediated Differentiation

Academic Background

Glioblastoma (GBM) is one of the deadliest brain cancers in adults, with a median survival period of only 15 to 18 months for patients. Although surgery combined with chemoradiotherapy can delay disease progression, these treatments cannot fully control tumor growth, and targeted therapies and biologics have also failed to significantly improve patient survival rates. The complexity of glioblastoma and the presence of the blood-brain barrier (BBB) make traditional treatments less effective. In recent years, differentiation therapy has emerged as a new treatment strategy that attempts to inhibit tumor growth by inducing tumor cells to differentiate into non-proliferating cells. However, the clinical effectiveness of differentiation therapy is limited, mainly due to the resistance of tumor cells to differentiation and insufficient precision of the treatment.

Based on previous findings, this study proposes that radiation not only kills tumor cells but also induces surviving cells into a state of multipotency. This state gives tumor cells greater plasticity, providing a new opportunity for differentiation therapy. The research team proposed a new treatment strategy: inducing glioblastoma cells into a multipotent state through radiation, followed by using forskolin — a known adenylate cyclase activator — to further induce tumor cells to differentiate into neuron-like or microglia-like cells, thereby inhibiting tumor proliferation and recurrence.

Source of the Paper

This paper was co-authored by Ling He, Daria Azizad, Kruttika Bhat, and others, primarily from various departments at the University of California, Los Angeles (UCLA), including the Department of Radiation Oncology, the Department of Biochemistry, and the Neuroscience Institute. The study was published in the journal PNAS (Proceedings of the National Academy of Sciences) on February 26, 2025, titled “Radiation-induced cellular plasticity primes glioblastoma for forskolin-mediated differentiation.”

Research Process and Results

1. Radiation-Induced Multipotent State

The study first verified whether radiation could induce glioblastoma cells into a multipotent state. Researchers subjected patient-derived HK-374 glioma cells to 4 Gy of radiation and examined epigenetic changes 48 hours later. The results showed that radiation significantly increased the open chromatin state in the promoter regions of developmental transcription factors, indicating that the cells had entered a multipotent state. This result provided a basis for subsequent differentiation therapy.

2. Forskolin Induces Neuron-Like Differentiation

To verify whether forskolin could induce irradiated glioma cells to differentiate into neuron-like cells, researchers added forskolin to the irradiated cells and detected the expression of neuronal markers (such as Tuj-1 and NF-LC). The results showed that forskolin treatment significantly increased the expression of these markers, and the cells exhibited morphological changes resembling neurons. This result indicates that forskolin can effectively induce irradiated glioma cells to differentiate into neuron-like cells.

3. Single-Cell RNA Sequencing Reveals Cell Fate

To further investigate the impact of combined forskolin and radiation treatment on the fate of glioma cells, researchers conducted single-cell RNA sequencing (scRNA-seq). The results showed that the combined treatment significantly increased the proportion of microglia-like and neuron-like cells while reducing the number of glioma stem cells (GSCs). This finding suggests that combined treatment can inhibit tumor growth by inducing cell differentiation into non-proliferative cells.

4. In Vivo Experiments Validate Treatment Efficacy

Researchers validated the efficacy of combined treatment in two mouse models (NSG mice and C57BL/6 mice). The results showed that combined treatment significantly reduced the number of tumor stem cells and prolonged the survival of the mice. Especially in the C57BL/6 mouse model, combined treatment extended the median survival from 36 days to 129 days. This result indicates that the combination of forskolin and radiation has significant anti-tumor effects in vivo.

Conclusions and Significance

This study shows that radiation can induce glioblastoma cells into a multipotent state, and forskolin can further induce these cells to differentiate into neuron-like or microglia-like cells, thereby inhibiting tumor proliferation and recurrence. This combined treatment strategy not only demonstrated significant effects in in vitro experiments but also validated its anti-tumor activity in mouse models. The findings provide new insights into the treatment of glioblastoma, particularly by suppressing the self-renewal ability of tumor stem cells through differentiation therapy.

Research Highlights

1. Innovative Treatment Strategy: This study is the first to propose the combined use of radiation and forskolin to inhibit tumor growth by inducing tumor cells to differentiate into non-proliferative cells.
2. Utilization of Multipotent State: The study reveals that the multipotent state induced by radiation provides a new opportunity for differentiation therapy, offering a new biological foundation for cancer treatment.
3. Validation Through In Vitro and In Vivo Experiments: The study not only validated the efficacy of combined treatment in vitro but also confirmed its anti-tumor activity through mouse models, providing strong support for clinical translation.

Other Valuable Information

The research team also pointed out that forskolin can cross the blood-brain barrier, which facilitates its clinical application. Additionally, the study found that forskolin treatment not only induced neuron-like differentiation but also increased the proportion of microglia-like cells, providing new directions for further research on the regulation of the tumor microenvironment.

Through innovative treatment strategies and in-depth mechanistic studies, this research offers new hope for the treatment of glioblastoma and lays a solid foundation for future clinical studies.