# Neuronal Differentiation of GBM-Initiating Cells Combined with Elimination of Undifferentiated Cells Preserves Motor Function

## TL;DR

A treatment combining ISX9 and BRQ can differentiate brain tumor cells into neurons and preserve motor function in mice with glioblastoma.

## Contribution

A novel therapeutic strategy using neuronal differentiation and targeted elimination of undifferentiated glioblastoma-initiating cells is proposed.

## Key findings

- ISX9 induces glioblastoma-initiating cells to differentiate into neurons.
- Combining ISX9 with BRQ eradicates undifferentiated cells and inhibits tumor growth.
- The treatment preserves motor function and promotes synapse-like connections in tumor-bearing mice.

## Abstract

What are the main findings?
Sequential ISX9 and BRQ administration drove neuronal differentiation in GICs and eliminated undifferentiated GICs in a brain tumor.ISX9 treatment promoted structural integration with host neurons and improved motor performance in tumor-bearing mice.

Sequential ISX9 and BRQ administration drove neuronal differentiation in GICs and eliminated undifferentiated GICs in a brain tumor.

ISX9 treatment promoted structural integration with host neurons and improved motor performance in tumor-bearing mice.

What are the implications of the main findings?
The combination can be used for maintaining neuronal functions in patients with GBM.Intrathecal injection can be used for delivering non-BBB penetrating chemicals into brain.

The combination can be used for maintaining neuronal functions in patients with GBM.

Intrathecal injection can be used for delivering non-BBB penetrating chemicals into brain.

Glioblastoma (GBM) is an aggressive human malignancy. Recent advances in GBM research have highlighted innovative therapeutic approaches, including the use of small molecules that eliminate GBM in mouse models. However, there are few reports on the restoration of lost neuronal functions in patients. Considering that GBM contains GBM-initiating cells (GICs) with characteristics of both cancer and neural stem cells, we investigated whether GICs could be redirected toward non-tumorigenic neurons to support the preservation of neural function in the brain with GBM. We demonstrated that the neuronal differentiation inducer Isoxazole 9 (ISX9) effectively induced GICs to differentiate into neurons, accompanied by significant changes in their gene expression profiles. The sequential application of ISX9 and the DHODH inhibitor brequinar (BRQ), which successfully eradicated undifferentiated GICs, not only promoted neuronal differentiation but also inhibited GIC tumorigenesis in the mouse brain, leading to prolonged survival and preservation of motor function in tumor-bearing mice. Furthermore, pathological analysis revealed that this combination not only reduced the size of GIC brain tumors but also facilitated the formation of synapse-like structural contacts between GIC-derived cells and host mouse neurons, suggesting remodeling of the tumor–neural interface within the tumor-developed area. Collectively, these findings suggest that the modulation of tumorigenic GIC differentiation may represent a strategy to preserve neural circuit integrity within the tumor-bearing brain.