title: Synthetic Smac/DIABLO peptides enhance the effects of chemotherapeutic agents by binding XIAP and cIAP1 in situ.
abstract: Inhibitor of apoptosis proteins (IAPs) interact with and inhibit caspases-3, -7, and -9. This interaction can be inhibited by Smac/DIABLO, a polypeptide released from mitochondria upon initiation of the apoptotic signaling process. Here we demonstrate that the first 4-8 N-terminal amino acids of Smac/DIABLO fused to the Drosophila antennapaedia penetratin sequence, a carrier peptide, enhance the induction of apoptosis and long term antiproliferative effects of diverse antineoplastic agents including paclitaxel, etoposide, 7-ethyl-10-hydroxycamptothecin (SN-38), and doxorubicin in MCF-7 breast cancer cells. Similar effects were observed in additional breast cancer and immortalized cholangiocyte cell lines. Further analysis demonstrated that the Smac-penetratin fusion peptide crossed the cellular membrane, bound XIAP and cIAP1, displaced caspase-3 from cytoplasmic aggregates, and enhanced drug-induced caspase action in situ. These studies demonstrate that inhibition of IAP proteins can modulate the efficacy of antineoplastic agents.
authors.affiliation: Department of Molecular Pharmacology and Experimental Therapeutics, Mayo Graduate School, Rochester, Minnesota 55905, USA.
authors.forename: Christina R
authors.initials: CR
authors.lastname: Arnt
authors.forename: Mihnea V
authors.initials: MV
authors.lastname: Chiorean
authors.forename: Michael P
authors.initials: MP
authors.lastname: Heldebrant
authors.forename: Gregory J
authors.initials: GJ
authors.lastname: Gores
authors.forename: Scott H
authors.initials: SH
authors.lastname: Kaufmann
mesh_terms: D000595:Amino Acid Sequence; D000970:Antineoplastic Agents / Q000494:pharmacology; D017209:Apoptosis; D051017:Apoptosis Regulatory Proteins; D002166:Camptothecin / Q000031:analogs & derivatives* / Q000494:pharmacology; D002352:Carrier Proteins / Q000737:chemistry* / Q000378:metabolism; D053148:Caspase 3; D053179:Caspase 7; D053453:Caspase 9; D020169:Caspases / Q000378:metabolism; D004305:Dose-Response Relationship, Drug; D004317:Doxorubicin / Q000494:pharmacology; D005047:Etoposide / Q000494:pharmacology; D006801:Humans; D015151:Immunoblotting; D051034:Inhibitor of Apoptosis Proteins; D047908:Intracellular Signaling Peptides and Proteins; D000077146:Irinotecan; D024101:Mitochondrial Proteins / Q000737:chemistry* / Q000378:metabolism; D008969:Molecular Sequence Data; D017239:Paclitaxel / Q000494:pharmacology; D010455:Peptides / Q000737:chemistry / Q000378:metabolism; D011485:Protein Binding; D017434:Protein Structure, Tertiary; D011506:Proteins / Q000737:chemistry* / Q000378:metabolism; D011993:Recombinant Fusion Proteins / Q000378:metabolism; D017386:Sequence Homology, Amino Acid; D014407:Tumor Cells, Cultured; D044767:Ubiquitin-Protein Ligases; D051636:X-Linked Inhibitor of Apoptosis Protein
chemical_list: D000970:Antineoplastic Agents; D051017:Apoptosis Regulatory Proteins; D002352:Carrier Proteins; C412403:DIABLO protein, human; D051034:Inhibitor of Apoptosis Proteins; D047908:Intracellular Signaling Peptides and Proteins; D024101:Mitochondrial Proteins; D010455:Peptides; D011506:Proteins; D011993:Recombinant Fusion Proteins; D051636:X-Linked Inhibitor of Apoptosis Protein; C496866:XIAP protein, human; D005047:Etoposide; D000077146:Irinotecan; D004317:Doxorubicin; C494833:BIRC2 protein, human; D044767:Ubiquitin-Protein Ligases; C505407:CASP3 protein, human; C505520:CASP7 protein, human; C506433:CASP9 protein, human; D053148:Caspase 3; D053179:Caspase 7; D053453:Caspase 9; D020169:Caspases; D017239:Paclitaxel; D002166:Camptothecin