title: The heat-shock protein 90 inhibitor, geldanamycin, induces apoptotic cell death in Epstein-Barr virus-positive NK/T-cell lymphoma by Akt down-regulation.
abstract: NK/T-cell lymphoma (NKTL) is strongly associated with latent Epstein-Barr virus (EBV) infection. Recently, latent membrane protein 1 (LMP1), an EBV oncoprotein, was reported to activate the phosphatidylinositol-3 kinase (PI3K)/Akt pathway for cell survival. Because geldanamycin (GA) and its derivative, 17-allylamino-17-demethoxygeldanamycin (17-AAG), exhibit anti-tumour activity by degrading HSP90 client proteins, including Akt, we investigated the effect of GA and 17-AAG on the survival of NKTL cell lines. EBV-positive NKTL cell lines, Hank-1 and NK-YS, and an EBV-negative NK leukaemia cell line, NK-L, were treated with PI3K and Akt inhibitors, GA, and 17-AAG, and were subjected to apoptosis and cell viability assays, and immunoblot analysis. EBV-positive B-lymphoblastoid cell lines IM9 and LMP1-transfected IM9 (IM9-LMP1) were also included. Hank-1 and NK-YS cell viability was compromised and apoptosis was induced by LY294002 (PI3K inhibitor) or Akt inhibitor II. GA or 17-AAG administration resulted in the apoptosis of NKTL cells, accompanied by Akt and pAkt down-regulation, caspase 3 activation, and mitochondrial membrane potential disruption. The intrinsic level of pAkt was higher in EBV-positive NKTL cells than in EBV-negative NK-L, and GA or 17-AAG decreased the viability of NKTL cells more efficiently than NK-L. Moreover, IM9-LMP1 was more sensitive to Akt inhibitor II or HSP90 inhibitors than IM9. Importantly, GA showed little effect on the viability of normal peripheral NK cells as non-neoplastic counterparts for comparison. In conclusion, this study suggests that the PI3K/Akt pathway is frequently activated in EBV-positive NKTL and that therapeutic modalities based on targeting the PI3K/Akt pathway with HSP90 inhibitors could be useful for achieving NKTL control.
authors.affiliation: Department of Pathology and Tumor Immunity Medical Research Center, Cancer Research Institute, Seoul National University College of Medicine, Seoul, Korea.
authors.forename: Y K
authors.initials: YK
authors.lastname: Jeon
authors.forename: C H
authors.initials: CH
authors.lastname: Park
authors.forename: K-Y
authors.initials: KY
authors.lastname: Kim
authors.forename: Y C
authors.initials: YC
authors.lastname: Li
authors.forename: J
authors.initials: J
authors.lastname: Kim
authors.forename: Y A
authors.initials: YA
authors.lastname: Kim
authors.forename: J-H
authors.initials: JH
authors.lastname: Paik
authors.forename: B-K
authors.initials: BK
authors.lastname: Park
authors.forename: C-W
authors.initials: CW
authors.lastname: Kim
authors.forename: Y-N
authors.initials: YN
authors.lastname: Kim
mesh_terms: D000903:Antibiotics, Antineoplastic / Q000494:pharmacology*; D017209:Apoptosis / Q000187:drug effects*; D016227:Benzoquinones / Q000494:pharmacology*; D002470:Cell Survival; D015536:Down-Regulation / Q000187:drug effects; D004353:Drug Evaluation, Preclinical; D018841:HSP90 Heat-Shock Proteins / Q000037:antagonists & inhibitors*; D004854:Herpesvirus 4, Human / Q000302:isolation & purification*; D006801:Humans; D047029:Lactams, Macrocyclic / Q000494:pharmacology*; D016393:Lymphoma, B-Cell / Q000378:metabolism / Q000473:pathology / Q000821:virology; D054391:Lymphoma, Extranodal NK-T-Cell / Q000378:metabolism / Q000473:pathology*; D053078:Membrane Potential, Mitochondrial / Q000502:physiology; D051058:Oncogene Protein v-akt / Q000378:metabolism; D019869:Phosphatidylinositol 3-Kinases / Q000378:metabolism; D015398:Signal Transduction; D014407:Tumor Cells, Cultured
chemical_list: D000903:Antibiotics, Antineoplastic; D016227:Benzoquinones; D018841:HSP90 Heat-Shock Proteins; D047029:Lactams, Macrocyclic; C112765:tanespimycin; D019869:Phosphatidylinositol 3-Kinases; D051058:Oncogene Protein v-akt; C001277:geldanamycin