Requirement of b-myb function for survival and differentiative potential of human neuroblastoma cells.

The B- myb gene belongs to a family of transcription factors that also includes A- myb and c- myb. B- myb is expressed in many cell types including human neuroblastoma cells. Here we demonstrate that B- myb expression is down-regulated during retinoic acid-induced neural and glial differentiation of neuroblastoma cells. This modulation is an early event, is maintained at late times of induction, and is in part regulated at the transcriptional level. Constitutive expression of B- myb prevents retinoic acid-induced neural differentiation as reflected by morphological features and the expression of (or lack of) biochemical markers associated with the undifferentiated phenotype. Furthermore, the expression of antisense B- myb transcripts does not allow the rescue of viable cells, suggesting an important role for B- myb in the survival of neuroblastoma cells. These results indicate that B- myb plays a functional role in the differentiative potential of neuroblastoma cells, raising the possibility that this gene is one of the nuclear regulators in the cascade of events leading to cellular differentiation.