The effect of N-myc amplification and expression on invasiveness of neuroblastoma cells

Most neuroblastomas with N-myc amplification, a sign of extremely poor prognosis, are extensively invasive to surrounding tissues. Therefore, we investigated the relationship between N-myc amplification and invasiveness of neuroblastoma cells, using an in-vitro assay system. Five human neuroblastoma cell lines were used for this study. IMR-32, GOTO, and DZ, all of which had N-myc amplification, showed a highly invasive capacity. In contrast, SK-N-SH without N-myc amplification showed extremely low invasiveness. ST unexpectedly showed high invasiveness in spite of the lack of N-myc amplification. Treatment of GOTO with 10(-5) mol/L all-trans-retinoic acid (RA) for 72 hours markedly decreased both N-myc expression and invasiveness. Treatment of GOTO with 2 mmol/L dibutyryl cyclic AMP (dbcAMP) for 72 hours caused a slight decrease of N-myc expression and invasiveness. These results indicate that N-myc amplification and expression might be closely related to the invasiveness of human neuroblastoma cells.