All-trans-retinoic acid induces nuclear factor kappaB activation and matrix metalloproteinase-9 expression and enhances basement membrane invasivity of differentiation-resistant human SK-N-BE 9N neuroblastoma Cells.

A comparison between retinoic acid (RA) differentiation-resistant and differentiation-sensitive SK-N-BE neuroblastoma (NB) cell lines revealed an association between resistance to differentiation, exhibited by N-myc stable transfected SK-N-BE 9N cells, with sensitivity to RA induction of p50/p65 nuclear factor B (NF-B) transcription factor activity and induction of matrix metalloproteinase (MMP)-9 expression leading to enhanced invasive behavior in vitro. These effects were not observed in differentiation-sensitive parental SK-N-BE or controltransfected SK-N-BE 2N counterparts. RA activated a MMP-9 promoter reporter gene construct in SK-N-BE 9N but not parental SK-N-BE or SK-N-BE 2N cells through a NF-B element (600) in association with enhanced p50 mRNA expression, reduced cytoplasmic inhibitor of nuclear factor B protein levels, and the induction of nuclear p50/p65 containing MMP-9 NF-B site binding activity. RA activation of the MMP-9