1-(5-ISOQUINOLINESULFONYL)-2-METHYLPIPERAZINE INDUCES APOPTOSIS IN HUMAN NEUROBLASTOMA-CELLS, SH-SY5Y, THROUGH A P53-DEPENDENT PATHWAY

We have studied the effect of 1-(5-isoquinolinylsuIfonyl)-2-methylpipe razine (H-7), a protein kinase inhibitor, on the regulation of apoptos is in the human neuroblastoma cell line, SH-SY5Y. H-7 (20-100 mu M) in duced apoptosis in these cells characterized by DNA fragmentation and chromatin condensation, Immunoblot analyses were performed with specif ic antibody against BCL-2, BCL-X(S/L), BAX, JUNB, c-JUN, ICH-1(L), c-F OS, RB, CDK-2, and p53, H-7 treatment did not significantly alter the level of these proteins with the exception of p53, H-7, but not stauro sporine, caused a dramatic nuclear accumulation of p53, The kinetics o f nuclear accumulation of p53 correlates well with the kinetics of ind uction of apoptosis, The effect of H-7 was further assessed in a group of human cell lines, Only cell lines harboring the wild-type p53 gene were responsive to the stimulatory effect of H-7 on nuclear accumulat ion of p53, Furthermore, cell. lines carrying a mutated p53 gene were resistant to the cytotoxic effect of H-7, The ability of H-7 in mediat ing apoptosis in the SH-SY5Y line expressing a dominant negative mutan t of p53 was significantly diminished, Taken together, these data stro ngly suggest that a p53-dependent mechanism contributes to the cytotox icity of H-7 in human neuroblastoma cells.