Induction of apoptosis in prostate carcinoma cells by BH3 peptides which inhibit Bak/Bcl-2 interactions.
Interactions between proteins of the Bcl-2 family play an important role in the regulation of apoptosis. Anti-apoptotic family members can heterodimerize with pro-apoptotic family members and antagonize their function, thus protecting against death. In cells protected from death by overexpression of Bcl-2 much of the Bax is present in Bax/Bcl-2 hetero-multimers and its death signal is blocked as it cannot homodimerize. This led us to use the Bcl-2/Bax heterodimer as a target for new compounds which may provide a therapy particularly suited to tumour cells for which resistance to conventional therapy is associated with elevated expression of Bcl-2. We assessed whether apoptosis could be induced in prostate tumour cells by blocking this heterodimerization with synthetic peptide sequences derived from the BH3 domain of pro-apoptotic Bcl-2 family members. Prostate cells were found to undergo up to 40% apoptosis 48 h following the introduction of synthetic peptides from the BH3 domains of Bax and Bak. The caspase inhibitor z-VAD.fmk provided protection against apoptosis mediated by these peptides. Immunoprecipitation studies revealed that introduction of peptides derived from the BH3 regions of Bak and Bax into cells blocked Bak/Bcl-2 heterodimerization. These data suggest that by blocking the dimerization through which Bcl-2 would normally inhibit apoptosis the apoptotic pathway driven by Bak was re-opened.
Finnegan
N M
NM
Dept of Biochemistry, University College Cork, Lee Maltings, Prospect Row, Cork, Ireland.
Curtin
J F
JF
Prevost
G
G
Morgan
B
B
Cotter
T G
TG
D000590:Amino Acid Chloromethyl Ketones / Q000494:pharmacology; D000595:Amino Acid Sequence; D017209:Apoptosis / Q000187:drug effects* / Q000502:physiology; D015153:Blotting, Western; D061945:Caspase Inhibitors; D015853:Cysteine Proteinase Inhibitors / Q000494:pharmacology; D019281:Dimerization; D018274:Electroporation; D006801:Humans; D008297:Male; D008565:Membrane Proteins / Q000037:antagonists & inhibitors* / Q000378:metabolism; D008969:Molecular Sequence Data; D009842:Oligopeptides / Q000008:administration & dosage / Q000494:pharmacology*; D010446:Peptide Fragments / Q000008:administration & dosage / Q000494:pharmacology*; D011233:Precipitin Tests; D011471:Prostatic Neoplasms / Q000188:drug therapy / Q000378:metabolism / Q000473:pathology*; D017434:Protein Structure, Tertiary; D011518:Proto-Oncogene Proteins / Q000378:metabolism; D019253:Proto-Oncogene Proteins c-bcl-2 / Q000037:antagonists & inhibitors* / Q000378:metabolism / Q000494:pharmacology; D014407:Tumor Cells, Cultured; D050998:bcl-2 Homologous Antagonist-Killer Protein; D051028:bcl-2-Associated X Protein
D000590:Amino Acid Chloromethyl Ketones; C494772:BAK1 protein, human; C494826:BAX protein, human; D061945:Caspase Inhibitors; D015853:Cysteine Proteinase Inhibitors; D008565:Membrane Proteins; D009842:Oligopeptides; D010446:Peptide Fragments; D011518:Proto-Oncogene Proteins; D019253:Proto-Oncogene Proteins c-bcl-2; D050998:bcl-2 Homologous Antagonist-Killer Protein; D051028:bcl-2-Associated X Protein; C096713:benzyloxycarbonylvalyl-alanyl-aspartyl fluoromethyl ketone