title: Different regulation of N- and c-myc expression during phorbol ester-induced maturation of human SH-SY5Y neuroblastoma cells.
abstract: The mRNA expression of c-myc and N-myc in the human neuroblastoma cell line SH-SY5Y was found not to change appreciably during the cell cycle and was also unaffected by proliferative inhibition induced by serum starvation or polyamine depletion. However, an early (0.5-8.0 h post-induction) transient reduction of c- and N-myc transcripts were observed in these cells upon induction to differentiation with the phorbol ester 12-O-tetradecanoylphorbol-13-acetate (TPA). Treatment of these neuroblastoma cells with TPA for longer periods (1-8 days), which induces morphological and functional differentiation and growth arrest, was followed by decreased expression of both myc genes. However, the rate of disappearance differed considerably. The N-myc mRNA level was slightly decreased after 4 days and was still detectable 8 days after induction, whereas the c-myc transcript was down-regulated much faster. In contrast, when the cells were exposed to retinoic acid, which results in a maturation along an alternative pathway, the inhibition of N-myc and c-myc expression was similar. The c-fos mRNA expression increased in TPA-treated SH-SY5Y cells and remained high during extended exposure to the drug. The highest c-fos transcript level in induced cells coincided in time with the transient reduction of N-myc and c-myc. Thus, the TPA-induced neuronal differentiation of SH-SY5Y cells was compatible with high c-fos and a substantial N-myc mRNA expression.
authors.affiliation: Department of Pathology, University of Uppsala, Sweden.
authors.forename: U
authors.initials: U
authors.lastname: Hammerling
authors.forename: C
authors.initials: C
authors.lastname: Bjelfman
authors.forename: S
authors.initials: S
authors.lastname: Påhlman
mesh_terms: D002453:Cell Cycle; D002454:Cell Differentiation / Q000187:drug effects; D005786:Gene Expression Regulation; D009447:Neuroblastoma / Q000235:genetics*; D011518:Proto-Oncogene Proteins / Q000235:genetics*; D011519:Proto-Oncogenes; D013755:Tetradecanoylphorbol Acetate / Q000494:pharmacology; D014212:Tretinoin / Q000494:pharmacology
chemical_list: D011518:Proto-Oncogene Proteins; D014212:Tretinoin; D013755:Tetradecanoylphorbol Acetate