Post-transcriptional down-regulation of Atoh1/Math1 by bone morphogenic proteins suppresses medulloblastoma development.

Bone morphogenic proteins 2 and 4 (BMP2 and BMP4) inhibit proliferation and induce differentiation of cerebellar granule neuron progenitors (GNPs) and primary GNP-like medulloblastoma (MB) cells. This occurs through rapid proteasome-mediated degradation of Math1 (Atoh1), a transcription factor expressed in proliferating GNPs. Ectopic expression of Atoh1, but not of Sonic hedgehog (Shh)-regulated Gli1 or Mycn, cancels these BMP-mediated effects and restores Shh-dependent proliferation of GNPs and MB cells in vitro and in vivo. Genes regulating the BMP signaling pathway are down-regulated in mouse MBs. Thus, BMPs are potent inhibitors of MB and should be considered as novel therapeutic agents.