EAPH-12. CELASTROL INDUCED DEGRADATION OF FANCD2 SENSITIZES PEDIATRIC HIGH-GRADE GLIOMA TO THE DNA-CROSSLINKING AGENT CARBOPLATIN

Pediatric high-grade gliomas (pHGG) are the leading cause of cancer-related death during childhood. Due to their diffuse growth pattern, difficult to reach location during surgery and position behind the blood-brain barrier (BBB), prognosis of pHGG has barely improved, despite decades of research. Celastrol is a naturally occuring compound that crosses the BBB and seems to have several anti-inflammatory and antioxidative properties. In our and other studies, celastrol has been found to induce proteasomal degradation of FANCD2, a core component of the Fanconi DNA-repair mechanism. Publicly available gene expression datasets reveal FANCD2 to be strongly upregulated in pHGG compared to healthy brain tissues and low-grade glioma. Therefore, we hypothesized that pHGG cells are highly dependent on their Fanconi repair mechanism and that disruption of this mechanism could sensitize the tumor to DNA-crosslinking agents. In eight primary pHGG cell cultures we showed FANCD2 to be degraded both in a time and dose dependent manner upon celastrol treatment. Subsequently, we determined cell-viability after celastrol treatment in these same models. Non-toxic celastrol concentrations were combined with carboplatin, a DNA-crosslinking agent that crosses the BBB. This showed significant synergistic cytotoxicity in all our primary pHGG cell cultures. Furthermore, celastrol and carboplatin combination treatment induced a significant synergistic increase in DNA damage at a range of concentrations, as determined by y-H2AX staining compared to treatment with single agents. These results imply that FANCD2 can serve as a chemosensitizer in pHGG. Combination therapy using celastrol and carboplatin might serve as a potential treatment for pHGG