title: Melittin enhances apoptosis through suppression of IL-6/sIL-6R complex-induced NF-κB and STAT3 activation and Bcl-2 expression for human fibroblast-like synoviocytes in rheumatoid arthritis.
abstract: OBJECTIVE
  Resistance to apoptosis of fibroblast-like synoviocytes (FLS) is considered as a major characteristic in RA. This study was designed to identify whether melittin has a pro-apoptotic effect in IL-6/sIL6R-stimulated human FLS by investigating the expression of mitochondrial apoptosis-related genes, nuclear factor-κB (NF-κB), and signal transducer and activators of transcription (STAT) activation.
  
  
  METHODS
  Cell viability was determined using a MTT assay after melittin treatment. Expressions of STAT3 and mitochondrial apoptosis-related genes induced by the IL-6/sIL-6R complex were determined by real time-polymerase chain reaction and western blotting. The expression of NF-κB p65 following IL-6 stimulation was determined by western blot analysis. The effects of melittin on the expression of apoptosis-related genes and the transcription factors NF-κB p65 and STAT3 were assessed in FLS. Apoptosis of FLS was determined by TUNEL-labeling to detect DNA strand breaks and DNA fragmentation assays. Caspase-3 activity was determined by a colorimetric assay.
  
  
  RESULTS
  IL-6/sIL-6R induced the activation of the transcription factors, STAT3, NF-κB p65 (nucleus), and Bcl-2. Melittin increased the expression of pro-apoptosis-related molecules, namely caspase-3, caspase-9, Apaf-1, and cytosolic cytochrome c, in a dose-dependent manner after treatment with IL-6/sIL-6R. Melittin inhibited STAT3 activation, translocation of NF-κB p65 into the nucleus, and expression of anti-apoptotic genes such as Bcl-2 and mitochondrial cytochrome c.
  
  
  CONCLUSIONS
  The pro-apoptotic effects of melittin likely result from inhibition of the activation of the transcription factors, STAT3 and NF-κB p65, and regulation of mitochondrial apoptosis-related genes. Melittin is thus a promising therapeutic option for RA as it induces apoptosis in apoptosis-resistant synoviocytes.
authors.affiliation: Department of Internal Medicine, Catholic University of Daegu School of Medicine, 3056-6 Daemyung 4-Dong, Namgu, Daegu 705-718, Republic of Korea.
authors.forename: Seong-Kyu
authors.initials: SK
authors.lastname: Kim
authors.forename: Ki-Yeun
authors.initials: KY
authors.lastname: Park
authors.forename: Wern-Chan
authors.initials: WC
authors.lastname: Yoon
authors.forename: Sung-Hoon
authors.initials: SH
authors.lastname: Park
authors.forename: Kwan-Kyu
authors.initials: KK
authors.lastname: Park
authors.forename: Dae-Hyun
authors.initials: DH
authors.lastname: Yoo
authors.forename: Jung-Yoon
authors.initials: JY
authors.lastname: Choe
mesh_terms: D017209:Apoptosis / Q000187:drug effects / Q000502:physiology; D001172:Arthritis, Rheumatoid / Q000188:drug therapy* / Q000378:metabolism / Q000473:pathology; D053148:Caspase 3 / Q000378:metabolism; D053181:Caspase 8 / Q000378:metabolism; D002470:Cell Survival / Q000187:drug effects / Q000502:physiology; D002478:Cells, Cultured; D005347:Fibroblasts / Q000166:cytology / Q000187:drug effects / Q000378:metabolism; D006801:Humans; D015850:Interleukin-6 / Q000378:metabolism*; D008555:Melitten / Q000494:pharmacology*; D016328:NF-kappa B / Q000378:metabolism*; D019253:Proto-Oncogene Proteins c-bcl-2 / Q000378:metabolism*; D019947:Receptors, Interleukin-6 / Q000378:metabolism; D050796:STAT3 Transcription Factor / Q000378:metabolism*; D015398:Signal Transduction / Q000187:drug effects / Q000502:physiology; D013583:Synovial Membrane / Q000166:cytology
chemical_list: C508600:IL6 protein, human; D015850:Interleukin-6; D016328:NF-kappa B; D019253:Proto-Oncogene Proteins c-bcl-2; D019947:Receptors, Interleukin-6; D050796:STAT3 Transcription Factor; C494086:STAT3 protein, human; D008555:Melitten; C505407:CASP3 protein, human; C505530:CASP8 protein, human; D053148:Caspase 3; D053181:Caspase 8