EXTH-60. OVERCOMING THE LEPTOMENINGEAL SEEDING OF MEDULLOBLASTOMA BY TARGETING HSP70

Abstract

Abstract Purpose The development of leptomeningeal seeding (LMS) through the cerebrospinal fluid (CSF) is a 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: By repeated transplantation, separation, culture, seeding and non-seeding MB cells were isolated. The cellular characteristics of each group were compared and differentially expressed genes (DEGs) were determined through gene expression profiling. The therapeutic effect of the selected inhibitor on the selected protein was tested in vitro and in vivo. RESULTS: We separated seeding and non-seeding cells triply, with the DEGs analysis indicating that heat shock protein 70 (HSP70) was in the highest rank in the expression profile of the seeding cells, and pathway enrichment analysis revealed that the metabolism was the main pathway enriched in seeding cells. The proliferation of seeding cells (S3) was slower than that of non-seeding cells (N3), but there was no significant difference in viability. Notably, the wound-healing of S3 was delayed, but the adhesion ability on collagen was higher than N3. We tested the effect of HSP70 suppression. Among the six HSP70 inhibitors, VER155008 was efficiently sensitive to S3, and suppression of MRP proteins with HSP70 was observed. Importantly, the treatment of VER155008 reduced LMS along the spinal cord in vivo. In addition, a synergistic effect was observed in the combination treatment of VER155008 with 4-hydroperoxycyclophosphamide. CONCLUSION: Our study suggests that targeting HSP70 can be a promising treatment option to suppress the LMS of MB.