title: Phosphorylated extracellular signal-regulated kinase up-regulated p53 expression in shikonin-induced HeLa cell apoptosis.
abstract: BACKGROUND
  The role of extracellular signal-regulated kinase 1/2 (ERK1/2) in shikonin-induced HeLa cells apoptosis remains vague. This study was to investigate the activation of caspase pathways and the role of ERK1/2 in human cervical cancer cells, HeLa, by shikonin.
  
  
  METHODS
  The inhibitory effect of shikonin on the growth of HeLa cells was measured by MTT assay. Fluorescent microscopic analysis of apoptotic cells stained with 4',6'-oliiamiclino-2-phenylindole C (DAPI) and Hoechst 33258 was carried out. Caspase-3 and -8 activities were detected using caspase-3 substrate and caspase-8 substrate as substrates, respectively. The protein levels of ERK, p53 and p-ERK were determined by Western blot analysis.
  
  
  RESULTS
  Shikonin inhibited cell growth in a time- and dose-dependent manner. Caspase-3 and caspase-8 were activated in the apoptotic process and caspase inhibitors effectively reversed shikonin-induced apoptosis. Phosphorylation of ERK resulted in up-regulation of p53 expression, which was blocked by mitogen-activated protein kinase (MEK), inhibitor PD 98059.
  
  
  CONCLUSIONS
  Shikonin induces HeLa cell apoptosis through the ERK, p53 and caspase pathways.
authors.affiliation: China-Japan Research Institute of Medical and Pharmaceutical Sciences, Shenyang Pharmaceutical University, Shenyang 110016, China.
authors.forename: Zhen
authors.initials: Z
authors.lastname: Wu
authors.forename: Li-jun
authors.initials: LJ
authors.lastname: Wu
authors.forename: Shinichi
authors.initials: S
authors.lastname: Tashiro
authors.forename: Satoshi
authors.initials: S
authors.lastname: Onodera
authors.forename: Takashi
authors.initials: T
authors.lastname: Ikejima
mesh_terms: D017209:Apoptosis / Q000187:drug effects*; D020169:Caspases / Q000502:physiology; D049109:Cell Proliferation / Q000187:drug effects; D004249:DNA Damage; D005419:Flavonoids / Q000494:pharmacology; D006367:HeLa Cells; D006801:Humans; D019950:Mitogen-Activated Protein Kinase 1 / Q000378:metabolism*; D048052:Mitogen-Activated Protein Kinase 3 / Q000378:metabolism*; D009285:Naphthoquinones / Q000494:pharmacology*; D010766:Phosphorylation; D016159:Tumor Suppressor Protein p53 / Q000032:analysis*; D015854:Up-Regulation
chemical_list: D005419:Flavonoids; D009285:Naphthoquinones; D016159:Tumor Suppressor Protein p53; C016101:shikonin; D019950:Mitogen-Activated Protein Kinase 1; D048052:Mitogen-Activated Protein Kinase 3; D020169:Caspases; C093973:2-(2-amino-3-methoxyphenyl)-4H-1-benzopyran-4-one