Enhanced potency of 9-cis versus all-trans-retinoic acid to induce the differentiation of human neuroblastoma cells.
All-trans-retinoic acid (ATRA) has been shown to be one of the most potent chemical inducers of human neuroblastoma differentiation. The recent discovery that the stereoisomer of ATRA, 9-cis-retinoic acid (9-cis-RA), binds to both the retinoic acid and retinoid X series of receptors prompted us to evaluate the ability of this compound to promote differentiation of this cell type. Using the LA-N-5 cell line, we have now determined that 9-cis-RA can induce the differentiation of human neuroblastoma cells as evidenced by dose-dependent inhibition of cell proliferation, neurite outgrowth, increased acetylcholinesterase activity, and reduction of N-myc mRNA expression. In comparing the effects of 9-cis-RA to ATRA, we found that while both compounds induced qualitatively similar cholinergic (versus adrenergic) features in LA-N-5 cells, 9-cis-RA was 5-to-10-fold more potent than ATRA in its antiproliferative and differentiation activity. These results were supported by transient transfection experiments utilizing chloramphenicol acetyltransferase (CAT) plasmid constructs containing a retinoic acid responsive regulatory element which showed a 2-to-3-fold increase in reporter gene activity induced with 9-cis-RA over that seen with ATRA at pharmacologically relevant retinoid concentrations (> 10(-8) M). Furthermore, we have determined that 9-cis-RA can significantly enhance mRNA levels of the nuclear retinoic acid receptors alpha and beta in LA-N-5 cells. Taken together, these findings have established the ability of 9-cis-RA to induce neuroblastoma differentiation and suggest that this retinoic acid isomer may have better therapeutic characteristics than ATRA.
Han
G
G
Department of Pathology and Laboratory Medicine (Neuropathology), UCLA School of Medicine 90095, USA.
Chang
B
B
Connor
M J
MJ
Sidell
N
N
D000110:Acetylcholinesterase / Q000378:metabolism; D000818:Animals; D002417:Cattle; D002454:Cell Differentiation / Q000187:drug effects; D002455:Cell Division / Q000187:drug effects; D015500:Chloramphenicol O-Acetyltransferase / Q000235:genetics / Q000378:metabolism; D004305:Dose-Response Relationship, Drug; D015870:Gene Expression / Q000187:drug effects; D016259:Genes, myc; D006801:Humans; D009447:Neuroblastoma; D009474:Neurons / Q000166:cytology* / Q000187:drug effects / Q000201:enzymology; D010957:Plasmids / Q000235:genetics; D012333:RNA, Messenger; D018168:Receptors, Retinoic Acid / Q000096:biosynthesis / Q000235:genetics; D013237:Stereoisomerism; D014162:Transfection; D014212:Tretinoin / Q000378:metabolism / Q000494:pharmacology*; D014407:Tumor Cells, Cultured; D014446:Tyrosine 3-Monooxygenase / Q000378:metabolism
D012333:RNA, Messenger; D018168:Receptors, Retinoic Acid; D014212:Tretinoin; D014446:Tyrosine 3-Monooxygenase; D015500:Chloramphenicol O-Acetyltransferase; D000110:Acetylcholinesterase