title: Targeting of X-linked inhibitor of apoptosis protein or survivin by short interfering RNAs sensitize hepatoma cells to TNF-related apoptosis-inducing ligand- and chemotherapeutic agent-induced cell death.
abstract: The inhibitors of apoptosis (IAPs) family regulate apoptosis by preventing the action of the central execution phase, and function as mediators and regulators of the anti-apoptotic activity of the v-Rel and NF-kappaB transcription factor families. The targeting of IAPs may be a promising strategy, but it is not well elucidated in human hepatocellular carcinomas (HCCs). We have therefore investigated the effects of the down-regulation of IAPs (XIAP or survivin) on the TNF-related apoptosis-inducing ligand (TRAIL) and chemotherapeutic agents that induced apoptosis in human HCC cells. To inhibit the IAPs gene expression, we designed small interfering RNA (siRNA) against the X-chromosome-linked IAP (XIAP) or survivin and investigated their efficacy in the suppression of the XIAP or survivin expression in two HCC cells (SK-Hep1 and HLE), and their consequent antitumor potential. We found that the designed siRNAs against the XIAP and survivin downregulated the protein expression of respective genes by almost 50%. The suppression of IAPs resulted in a significant decrease in procaspase-3 levels, especially by suppression of the XIAP. The apoptosis cell count was small in cells transfected with control siRNA and siRNA against the XIAP or survivin, but after treatment with 10 ng/ml of TRAIL, the apoptosis cells increased 2-3 times by the suppression of IAPs as control. The cytotoxicity of doxorubicin and camptothecin was augmented by the suppression of the XIAP in SK-Hep1 cells, whereas the suppression of survivin did not affect cytotoxicity. In conclusion, downregulation of the XIAP or survivin enhances cell death by TRAIL and increases sensitivity against some chemotherapeutic agents in HCC cells. In particular, the XIAP may be a potential target to increase therapeutic sensitivity.
authors.affiliation: First Department of Internal Medicine, Mie University School of Medicine, Edobashi 2-174, Tsu, Mie 514-8507, Japan.
authors.forename: Yumi
authors.initials: Y
authors.lastname: Yamaguchi
authors.forename: Katsuya
authors.initials: K
authors.lastname: Shiraki
authors.forename: Hiroyuki
authors.initials: H
authors.lastname: Fuke
authors.forename: Tomoko
authors.initials: T
authors.lastname: Inoue
authors.forename: Kazumi
authors.initials: K
authors.lastname: Miyashita
authors.forename: Yutaka
authors.initials: Y
authors.lastname: Yamanaka
authors.forename: Yukiko
authors.initials: Y
authors.lastname: Saitou
authors.forename: Kazushi
authors.initials: K
authors.lastname: Sugimoto
authors.forename: Takeshi
authors.initials: T
authors.lastname: Nakano
mesh_terms: D000903:Antibiotics, Antineoplastic / Q000494:pharmacology; D000972:Antineoplastic Agents, Phytogenic / Q000494:pharmacology; D017209:Apoptosis; D051017:Apoptosis Regulatory Proteins; D002166:Camptothecin / Q000494:pharmacology; D006528:Carcinoma, Hepatocellular / Q000235:genetics* / Q000473:pathology*; D015536:Down-Regulation; D004317:Doxorubicin / Q000494:pharmacology; D015972:Gene Expression Regulation, Neoplastic; D006801:Humans; D051034:Inhibitor of Apoptosis Proteins; D008024:Ligands; D008113:Liver Neoplasms / Q000235:genetics* / Q000473:pathology*; D008562:Membrane Glycoproteins / Q000502:physiology; D008869:Microtubule-Associated Proteins / Q000235:genetics* / Q000502:physiology*; D009363:Neoplasm Proteins / Q000235:genetics* / Q000502:physiology*; D011506:Proteins / Q000235:genetics / Q000502:physiology*; D034741:RNA, Small Interfering; D000077022:Survivin; D053221:TNF-Related Apoptosis-Inducing Ligand; D014407:Tumor Cells, Cultured; D014409:Tumor Necrosis Factor-alpha / Q000502:physiology; D051636:X-Linked Inhibitor of Apoptosis Protein
chemical_list: D000903:Antibiotics, Antineoplastic; D000972:Antineoplastic Agents, Phytogenic; D051017:Apoptosis Regulatory Proteins; C107489:BIRC5 protein, human; D051034:Inhibitor of Apoptosis Proteins; D008024:Ligands; D008562:Membrane Glycoproteins; D008869:Microtubule-Associated Proteins; D009363:Neoplasm Proteins; D011506:Proteins; D034741:RNA, Small Interfering; D000077022:Survivin; D053221:TNF-Related Apoptosis-Inducing Ligand; C505653:TNFSF10 protein, human; D014409:Tumor Necrosis Factor-alpha; D051636:X-Linked Inhibitor of Apoptosis Protein; C496866:XIAP protein, human; D004317:Doxorubicin; D002166:Camptothecin