11q deletion or ALK activity curbs DLG2 expression to maintain an undifferentiated state in neuroblastoma.

High-risk 11q deleted neuroblastomas (NBs) typically display an undifferentiated/poorly differentiated morphology. NB is thought to develop from Schwann cell precursors (SCPs) and un-differentiated neural crest derived cells (NCC). It is therefore vital to understand the mechanisms involved in the block of differentiation. We showed that an important and novel role for oncogenic ALK-ERK1/2-SP1 signaling may be the maintenance of an undifferentiated state of transformed NC-derived progenitors that is achieved by repression of DLG2, a tumor suppressor in NB. DLG2 is expressed in the ‘bridge signature’ that represents the transcriptional transition state when neural crest cells or Schwann Cell Precursors (SCP) become chromaffin cells of the adrenal gland. The importance of SP1 and DLG2 in this process is highlighted by our findings that restoring DLG2 expression spontaneously drives NB differentiation. Further, genetic analysis of high-risk 11q deletion NB patient identified genetic lesions in the DLG2 gene, Our data also suggest that further exploration of other ‘bridge genes’ may help to better understand the mechanisms underlying the differentiation of NC-derived progenitors and their contribution to NB.