title: Apoptosis induction associated with the ER stress response through up-regulation of JNK in HeLa cells by gambogic acid.
abstract: BACKGROUND
  Gambogic acid (GA) was extracted from the dried yellow resin of gamboge (Garcinia hanburyi) which is traditionally used as a coloring material for painting and cloth dying. Gamboge has been also used as a folk medicine for an internal purgative and externally infected wound. We focused on the mechanisms of apoptosis induction by GA through the unfold protein response (ER stress) in HeLa cells.
  
  
  METHODS
  The cytotoxic effect of GA against HeLa cells was determined by trypan blue exclusion assay. Markers of ER stress such as XBP-1, GRP78, CHOP, GADD34 and ERdj4 were analyzed by RT-PCR and Real-time RT-PCR. Cell morphological changes and apoptotic proteins were performed by Hoechst33342 staining and Western blotting technique.
  
  
  RESULTS
  Our results indicated a time- and dose-dependent decrease of cell viability by GA. The ER stress induction is determined by the up-regulation of spliced XBP1 mRNA and activated GRP78, CHOP, GADD34 and ERdj4 expression. GA also induced cell morphological changes such as nuclear condensation, membrane blebbing and apoptotic body in Hela cells. Apoptosis cell death detected by increased DR5, caspase-8, -9, and -3 expression as well as increased cleaved-PARP, while decreased Bcl-2 upon GA treatment. In addition, phosphorylated JNK was up-regulated but phosphorylated ERK was down-regulated after exposure to GA.
  
  
  CONCLUSIONS
  These results suggest that GA induce apoptosis associated with the ER stress response through up-regulation of p-JNK and down-regulation of p-ERK in HeLa cells.
authors.affiliation: Chulabhorn International College of Medicine, Thammasart University, Pratumthani, Thailand. krajarng@yahoo.com.|Department of Biochemistry, Faculty of Medicine, Srinakharinwirot University, Bangkok, Thailand. krajarng@yahoo.com.
authors.forename: Aungkana
authors.initials: A
authors.lastname: Krajarng
authors.affiliation: Department of Biosciences and Informatics, Faculty of Science and Technology, Keio University, Yokohama, Japan. imoto@bio.keio.ac.jp.
authors.forename: Masaya
authors.initials: M
authors.lastname: Imoto
authors.affiliation: Department of Biosciences and Informatics, Faculty of Science and Technology, Keio University, Yokohama, Japan. tashiro@bio.keio.ac.jp.
authors.forename: Etsu
authors.initials: E
authors.lastname: Tashiro
authors.affiliation: Department of Biosciences and Informatics, Faculty of Science and Technology, Keio University, Yokohama, Japan. Kamesan2hiki@hotmail.com.
authors.forename: Takahiro
authors.initials: T
authors.lastname: Fujimaki
authors.affiliation: Department of Biosciences and Informatics, Faculty of Science and Technology, Keio University, Yokohama, Japan. st_0619_shinjo@hotmail.com.
authors.forename: Satoko
authors.initials: S
authors.lastname: Shinjo
authors.affiliation: Department of Biochemistry, Faculty of Medicine, Srinakharinwirot University, Bangkok, Thailand. ramida.swu@gmail.com.
authors.forename: Ramida
authors.initials: R
authors.lastname: Watanapokasin
mesh_terms: D000972:Antineoplastic Agents, Phytogenic / Q000494:pharmacology / Q000627:therapeutic use; D017209:Apoptosis / Q000187:drug effects*; D002470:Cell Survival / Q000187:drug effects; D015536:Down-Regulation; D000091342:Endoplasmic Reticulum Chaperone BiP; D059865:Endoplasmic Reticulum Stress; D048049:Extracellular Signal-Regulated MAP Kinases / Q000378:metabolism; D005260:Female; D029760:Garcinia / Q000737:chemistry*; D006367:HeLa Cells; D006360:Heat-Shock Proteins / Q000378:metabolism; D006801:Humans; D048031:JNK Mitogen-Activated Protein Kinases / Q000378:metabolism*; D008517:Phytotherapy; D010936:Plant Extracts / Q000494:pharmacology / Q000627:therapeutic use; D015533:Transcriptional Activation / Q000187:drug effects; D015854:Up-Regulation; D002583:Uterine Cervical Neoplasms / Q000188:drug therapy* / Q000378:metabolism; D044004:Xanthones / Q000494:pharmacology / Q000627:therapeutic use*
chemical_list: D000972:Antineoplastic Agents, Phytogenic; D000091342:Endoplasmic Reticulum Chaperone BiP; C000717247:HSPA5 protein, human; D006360:Heat-Shock Proteins; D010936:Plant Extracts; D044004:Xanthones; C052659:gambogic acid; D048049:Extracellular Signal-Regulated MAP Kinases; D048031:JNK Mitogen-Activated Protein Kinases