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-methylpiperazine (H-7), a protein kinase inhibitor, on the regulation of apoptosis in the human neuroblastoma cell line, SH-SY5Y. H-7 (20-100 mu M) induced apoptosis in these cells characterized by DNA fragmentation and chromatin condensation, Immunoblot analyses were performed with specific antibody against BCL-2, BCL-X(S/L), BAX, JUNB, c-JUN, ICH-1(L), c-FOS, 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 staurosporine, caused a dramatic nuclear accumulation of p53, The kinetics of nuclear accumulation of p53 correlates well with the kinetics of induction 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 accumulation 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 mediating apoptosis in the SH-SY5Y line expressing a dominant negative mutant of p53 was significantly diminished, Taken together, these data strongly suggest that a p53-dependent mechanism contributes to the cytotoxicity of H-7 in human neuroblastoma cells.