Notch1 switches progenitor competence in inducing medulloblastoma

The identity of the cell of origin is a key determinant of cancer subtype, progression and prognosis. Group 3 Medulloblastoma (MB) is a malignant childhood brain cancer with poor prognosis and unknown cell of origin. We overexpressed the Group 3 MB genetic drivers MYC and Gfi1 in different candidate cells of origin in the postnatal mouse cerebellum. We found that S100b+ cells are competent to initiate Group 3 MB, while Math1+, Sox2+ or Ascl1+ cells are not. We noted that S100b+ cells have higher levels of Notch1 pathway activity compared to Math1+ cells. Interestingly, we found that additional activation of Notch1 in Math1+ cells was sufficient to induce Group 3 MB upon MYC/Gfi1 expression. Taken together, our data suggest that the MB cell of origin competence depends on the cellular identity, which relies on Notch1 activity. Graphical Abstract O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=141 SRC="FIGDIR/small/084335v1_ufig1.gif" ALT="Figure 1"> View larger version (20K): org.highwire.dtl.DTLVardef@83f999org.highwire.dtl.DTLVardef@77dc49org.highwire.dtl.DTLVardef@11f5267org.highwire.dtl.DTLVardef@15afa34_HPS_FORMAT_FIGEXP M_FIG C_FIG