Overcoming the leptomeningeal seeding of medulloblastoma by targeting HSP70

Abstract Purpose The development of leptomeningeal seeding (LMS) through the cerebrospinal fluid (CSF) is common in medulloblastoma (MB) and a major cause of treatment failure. The mechanism of MB LMS remains unclear, and effective treatment options are urgently required. This study aimed to discover molecules that can specifically target seeding cells by making a cellular model of MB LMS and analyzing their specific genetic and functional characteristics.Methods Through repeated transplantation, separation, culture, and characterization, seeding and non-seeding MB cells were isolated. A comprehensive analysis of the cellular characteristics was conducted, and differentially expressed genes (DEGs) were identified through gene expression profiling. In vitro and in vivo experiments were performed to evaluate the therapeutic effects of selected inhibitors targeting a specific protein.Results We successfully isolated seeding and non-seeding cells through a three-step process. Analysis of DEGs revealed heat shock protein 70 (HSP70) as the most highly expressed gene in the seeding cells, with metabolic pathways being prominently enriched. While seeding cells (S3) exhibited slower proliferation than non-seeding cells (N3), there was no significant difference in viability. Notably, S3 showed delayed wound-healing but increased collagen adhesion ability. HSP70 suppression experiments demonstrated that VER155008, among the six inhibitors tested, efficiently targeted S3 cells and inhibited the expression of multidrug resistance-associated protein (MRP) proteins. Importantly, in vivo treatment with VER155008 resulted in reduced LMS along the spinal cord. Furthermore, a synergistic effect was observed when VER155008 was combined with 4-hydroperoxycyclophosphamide.Conclusion Our findings suggest that targeting HSP70 holds promise as a potential treatment option to suppress LMS in MB.