Growth suppressing Wnt/BMP4-Msx/Notch signalling in neuroblastoma

The Wnt and bone morphogenetic protein signalling pathways are known to be crucial in the development of neural crest lineages, including the sympathetic nervous system. Surprisingly, their role in paediatric neuroblastoma, the prototypic tumour arising from this lineage, remains relatively uncharacterised. We previously demonstrated that Wnt/b-catenin can have cell-type specific effects on neuroblastoma phenotypes, including growth inhibition and differentiation, and that BMP4 was induced by Wnt signalling. In this study, we characterise the phenotypic effects of BMP4 on neuroblastoma cells, demonstrating convergent induction of MSX homeobox transcription factors by Wnt and BMP4 signalling and BMP4-induced growth suppression and differentiation. Immunohistochemical analysis of BMP4 expression in primary neuroblastomas confirms the absence of BMP4 in poorly differentiated tumours, together with high expression in ganglion cells. This is consistent with a tumour suppressive role for BMP4. RNA sequencing following BMP4 treatment revealed induction of Notch signalling, verified by increases of Notch3 and Hes1 proteins. Together, our data demonstrate for the first time Wnt-BMP-Notch crosstalk associated with growth suppression of neuroblastoma.