Differential gene regulation by 9-cis and all-trans retinoic acid in neuroblastoma cells

9-cis retinoic acid (RA) is more effective than all-trans RA at inducing neuroblastoma differentiation in vitro, and has distinct biological properties with respect to its ability to promote apoptosis in N-type neuroblastoma cells. The cellular effects of 9-cis RA may, in part, result from activation of retinoid X receptor (RXR) homodimers. If this hypothesis is correct, 9-cis RA may control the expression of a different subset of retinoid-regulated genes compared to all-trans RA.

We have therefore used differential mRNA display to identify genes differentially expressed in neuroblastoma cells in response to all-trans and 9-cis RA.

The majority of cDNAs differentially expressed in response to all-trans or 9-cis RA matched to nonredundant Genbank sequences or EST database sequences. Differential-display profiles were similar in SH SY 5Y and SH S EP cells, clonal derivatives of the mixed neuroblastoma cell line SK N SH, although there were apparent differences between these cell lines with respect to the retinoid-regulation of specific RT-PCR cDNA fragments.

These data support the view that 9-cis and all-trans RA act via different receptor mechanisms.