title: Functional proteomic analysis revels that the ethanol extract of Annona muricata L. induces liver cancer cell apoptosis through endoplasmic reticulum stress pathway.
abstract: BACKGROUND
  Annona muricata L. is used to treat cancer in some countries. Extracts of Annona muricata have been shown to cause apoptosis of various cancer cells in vitro, and inhibit tumor growth in vivo in animal models. However, the molecular mechanisms underlying its anti-cancer and apoptotic effects of the herb remain to be explored.
  
  
  OBJECTIVE
  The study investigated the molecular mechanisms underlying liver cancer cell apoptosis triggered by the ethanol extract of leaves of Annona muricata L.
  
  
  METHODS
  Liver cancer HepG2 cells were used as experimental model. MTT assay was employed to evaluate cell viability. Flow cytometry and TUNEL assays were performed to confirm apoptosis. We employed functional proteomic analysis to delineate molecular pathways underlying apoptosis triggered by the herbal extract.
  
  
  RESULTS
  We showed that the extract was able to reduce viability and trigger apoptosis of the cancer cells. Proteomic analysis identified 14 proteins associated with the extract-elicited apoptosis, which included the increased expression levels of HSP70, GRP94 and DPI-related protein 5. Western blot analysis confirmed that the extract did up-regulated the protein levels of HSP70 and GRP94. Results from bioinformatic annotation pulled out two molecular pathways for the extract, which, notably, included endoplasmic reticulum (ER) stress which was evidenced by the up-regulation of HSP70, GRP94 and PDI-related protein 5. Further examinations of typical protein signaling events in ER stress using western blot analysis have shown that the extract up-regulated the phorsphorelation of PERK and eIF2α as well as the expression level of Bip and CHOP.
  
  
  CONCLUSIONS
  Our results indicate that the ethanol extract of leaves of Annona muricata L. causes apoptosis of liver cancer cells through ER stress pathway, which supports the ethnomedicinal use of this herb as an alternative or complementary therapy for cancer.
authors.affiliation: School of Life Sciences, Shanxi University, Taiyuan, Shanxi, PR China.
authors.forename: Na
authors.initials: N
authors.lastname: Liu
authors.affiliation: School of Life Sciences, Shanxi University, Taiyuan, Shanxi, PR China.
authors.forename: Hua Li
authors.initials: HL
authors.lastname: Yang
authors.affiliation: School of Life Sciences, Shanxi University, Taiyuan, Shanxi, PR China.
authors.forename: Pu
authors.initials: P
authors.lastname: Wang
authors.affiliation: School of Life Sciences, Shanxi University, Taiyuan, Shanxi, PR China.
authors.forename: Yu Cheng
authors.initials: YC
authors.lastname: Lu
authors.affiliation: School of Life Sciences, Shanxi University, Taiyuan, Shanxi, PR China.
authors.forename: Ying Juan
authors.initials: YJ
authors.lastname: Yang
authors.affiliation: School of Life Sciences, Shanxi University, Taiyuan, Shanxi, PR China.
authors.forename: Lan
authors.initials: L
authors.lastname: Wang
authors.affiliation: School of Life Sciences, Shanxi University, Taiyuan, Shanxi, PR China. Electronic address: lee_shao@hotmail.com.
authors.forename: Shao Chin
authors.initials: SC
authors.lastname: Lee
mesh_terms: D031041:Annona / Q000737:chemistry*; D000972:Antineoplastic Agents, Phytogenic / Q000302:isolation & purification / Q000494:pharmacology*; D017209:Apoptosis / Q000187:drug effects*; D051017:Apoptosis Regulatory Proteins / Q000378:metabolism*; D014408:Biomarkers, Tumor / Q000378:metabolism*; D002470:Cell Survival / Q000187:drug effects; D019295:Computational Biology; D004305:Dose-Response Relationship, Drug; D015180:Electrophoresis, Gel, Two-Dimensional; D059865:Endoplasmic Reticulum Stress / Q000187:drug effects*; D000431:Ethanol / Q000737:chemistry*; D045325:HCT116 Cells; D056945:Hep G2 Cells; D006801:Humans; D008113:Liver Neoplasms / Q000188:drug therapy* / Q000378:metabolism / Q000473:pathology; D013058:Mass Spectrometry; D008517:Phytotherapy; D010936:Plant Extracts / Q000302:isolation & purification / Q000494:pharmacology*; D018515:Plant Leaves; D010946:Plants, Medicinal; D025941:Protein Interaction Mapping; D060066:Protein Interaction Maps; D040901:Proteomics / Q000379:methods*; D015398:Signal Transduction / Q000187:drug effects; D012997:Solvents / Q000737:chemistry*; D013997:Time Factors
chemical_list: D000972:Antineoplastic Agents, Phytogenic; D051017:Apoptosis Regulatory Proteins; D014408:Biomarkers, Tumor; D010936:Plant Extracts; D012997:Solvents; D000431:Ethanol
keywords: Annona muricata L.; Apoptosis; Cancer cells; ER stress; Ethanol extract; Functional proteomics