Synthetic Smac peptide enhances the effect of etoposide-induced apoptosis in human glioblastoma cell lines.
Smac/DIABLO is a mitochondrial protein released into cytosol during the progression of apoptosis. Smac/DIABLO promotes apoptosis by neutralizing the inhibitory effect of the inhibitor of apoptosis proteins (IAPs) on the processing and activity of the effecter of caspase. Here, we generated synthetic Smac peptide which possesses an IAP-binding domain and Drosophila antennapaedia penetration sequence, and examined whether it enhances the effect of the chemotherapeutic agent etoposide in the human glioblastoma cell line. Cellular uptake of Smac peptide in several glioma cell lines was most prominent at 6-12 h after addition. Caspase activity assay showed that our peptide successfully increased the activity of caspase-3 and caspase-9 in etoposide-induced apoptosis. In addition, Smac peptide increased the amount of cleaved PARP (poly ADP-ribose polymerase), but control peptides did not. Moreover, the addition of z-VAD-fmk, a caspase inhibitor, counterbalanced the effect of Smac peptide. Finally, we demonstrated that Smac peptide could enhance the growth inhibition effect of etoposide compared with control peptides. These results suggest that synthetic Smac peptide may be a new molecular targeting anti-tumor therapy for human glioblastoma.
Department of Neurosurgery, Kobe University Graduate School of Medicine, Chuo-ku, Kobe, Japan. mukyu@med.kobe-u.ac.jp
Katsu
K
Mizukawa
Atsufumi
A
Kawamura
Takashi
T
Sasayama
Kazuhiro
K
Tanaka
Masahito
M
Kamei
Masato
M
Sasaki
Eiji
E
Kohmura
D000972:Antineoplastic Agents, Phytogenic / Q000494:pharmacology*; D017209:Apoptosis / Q000187:drug effects* / Q000502:physiology; D051017:Apoptosis Regulatory Proteins; D001932:Brain Neoplasms / Q000188:drug therapy*; D020169:Caspases / Q000187:drug effects / Q000378:metabolism; D045744:Cell Line, Tumor; D053938:DNA Fragmentation / Q000187:drug effects; D004357:Drug Synergism; D005047:Etoposide / Q000494:pharmacology*; D005909:Glioblastoma / Q000188:drug therapy*; D006801:Humans; D047908:Intracellular Signaling Peptides and Proteins / Q000138:chemical synthesis / Q000378:metabolism / Q000494:pharmacology*; D024101:Mitochondrial Proteins / Q000138:chemical synthesis / Q000378:metabolism / Q000494:pharmacology*; D011994:Recombinant Proteins
D000972:Antineoplastic Agents, Phytogenic; D051017:Apoptosis Regulatory Proteins; C412403:DIABLO protein, human; D047908:Intracellular Signaling Peptides and Proteins; D024101:Mitochondrial Proteins; D011994:Recombinant Proteins; D005047:Etoposide; D020169:Caspases