title: Methylene chloride fraction of Scutellaria barbata induces apoptosis in human U937 leukemia cells via the mitochondrial signaling pathway.
abstract: BACKGROUND
  Scutellaria barbata D.Don has been applied to treat cancers, inflammation and urinary disease. However, its antitumor mechanism still remains unclear.
  
  
  METHODS
  With methylene chloride fraction of Herba Scutellariae barbatae (MCSB), apoptosis-related experiments were carried out on human U937 leukemia cells by (a) 2,3-bis[2-4-nitro-5-sulphophenyl]2H-tetrazolium-5-carboxanilide (XTT) assay for cytotoxicity; (b) terminal deoxynucleotidyl-transferase-mediated dUTP nick end labeling (TUNEL) assay for morphological changes; (c) cell cycle analysis; (d) Western blot analysis of poly(ADP-ribose) polymerase (PARP), caspase-8, caspase-9, caspase-3 and Bax, Bcl-2 and cytochrome c expressions for apoptosis signaling pathway.
  
  
  RESULTS
  MCSB inhibited the proliferation of human U937 leukemia cells in a dose-dependent manner (IC50 = approximately 10 microg/ml). MCSB dose-dependently increased the sub-G1 DNA contents by cell cycle analysis. DNA fragments indicating induction of apoptosis were observed in MCSB-treated U937 cells by TUNEL assay. Caspase-9 and caspase-3 were activated while caspase-8 was intact by MCSB. Similarly, MCSB effectively cleaved PARP, increased the ratio of Bax/Bcl-2 and released the cytochrome c from mitochondria during apoptosis in U937 cells.
  
  
  CONCLUSIONS
  Our results suggest that MCSB can induce apoptosis via the mitochondria-mediated signaling pathway.
authors.affiliation: Graduate School of East-West Medical Science, KyungHee University, Yoingin 449-701, South Korea.
authors.forename: Yun-Yi
authors.initials: YY
authors.lastname: Cha
authors.forename: Eun-Ok
authors.initials: EO
authors.lastname: Lee
authors.forename: Hyo-Jeong
authors.initials: HJ
authors.lastname: Lee
authors.forename: Young-Doo
authors.initials: YD
authors.lastname: Park
authors.forename: Seong-Gyu
authors.initials: SG
authors.lastname: Ko
authors.forename: Dong-Hee
authors.initials: DH
authors.lastname: Kim
authors.forename: Hyung-Min
authors.initials: HM
authors.lastname: Kim
authors.forename: In-Cheol
authors.initials: IC
authors.lastname: Kang
authors.forename: Sung-Hoon
authors.initials: SH
authors.lastname: Kim
mesh_terms: D017209:Apoptosis; D015153:Blotting, Western; D002453:Cell Cycle / Q000187:drug effects; D004305:Dose-Response Relationship, Drug; D005434:Flow Cytometry; D020869:Gene Expression Profiling; D006801:Humans; D020287:In Situ Nick-End Labeling; D008752:Methylene Chloride; D008928:Mitochondria / Q000502:physiology*; D010936:Plant Extracts / Q000494:pharmacology; D031363:Scutellaria; D015398:Signal Transduction; D012997:Solvents; D020298:U937 Cells
chemical_list: D010936:Plant Extracts; D012997:Solvents; D008752:Methylene Chloride