ABSTRACT
Medulloblastoma (MB), grouped as either WNTactivated, Sonic hedgehog (SHH)activated, or non-WNT/non-SHH group 3, accounts for almost 20% of all childhood brain cancers. In spite of current intensive treatments, not all patients are cured and survivors suffer from severe sideeffects. The present study therefore examined the effects of the polyADPribose polymerase (PARP) and WEE1like protein kinase (WEE1) inhibitors, BMN673 and MK1775, respectively, alone or in combination on four MB cell lines. More specifically, the MB cell lines, DAOY, UW2283, MED8A and D425, were tested for their sensitivity to BMN673 and MK1775 alone or in combination, using cell viability, cell confluency and cytotoxicity assays. The effects on the cell cycle phases were also examined using FACS analysis. Monotherapy with BMN673 and MK1775 exerted dosedependent inhibitory effects on the viability of almost all MB cell lines. Notably, when BMN673 and MK1775 were used in combination, synergistic effects were noted in the SHH group cell lines (DAOY and UW2283), but not in the already WEE1sensitive group 3 (MED8A and D425) lines. Moreover, the combination treatment decreased the percentage of cells in the G1 phase and induced the novel distribution of both DAOY and UW2283 cells in the S and G2/M phases, with the UW2283 cells exhibiting a greater delay. To conclude, MK1775 was efficient in all and BMN673 in most cell lines, and their combined use exerted synergistic effects on the SHH, but not the group 3 cell lines. These data suggest that MK1775 alone may be of interest for all MB cell lines, and that the combination of PARP/WEE1 inhibitors may provide possible therapeutic opportunities for the therapy of SHH MBs. Their use warrants further investigations in the future.