title: Swietenia macrophylla King induces mitochondrial-mediated apoptosis through p53 upregulation in HCT116 colorectal carcinoma cells.
abstract: BACKGROUND
  Swietenia macrophylla King is a traditional herb used to treat various diseases including hypertension, diabetes and cancer. Previous study demonstrated its anti-tumor effect but the potential mechanisms have not been clearly defined. The current study was to further investigate the underlying mechanism of ethyl acetate fraction of Swietenia macrophylla (SMEAF)-induced anti-proliferative effect and apoptosis in HCT116 colorectal carcinoma cell.
  
  
  METHODS
  Cell viability was evaluated in HCT116 cells by trypan blue exclusion assay. Apoptotic cell death was detected by Hoechst 33342/propidium iodide (PI) staining and intracellular reactive oxygen species (ROS) was analyzed by flow cytometry. The apoptotic gene and protein expression were determined by Real-time quantitative PCR (q-PCR) and immunofluorescence staining using flow cytometry, respectively.
  
  
  RESULTS
  SMEAF significantly inhibited HCT116 cell viability and induced apoptosis in a dose-dependent manner. SMEAF-induced apoptosis was triggered by the activation of p53 and intracellular reactive oxygen species (ROS) production. Moreover, the significant increase in p53 was accompanied by a decrease murine double minute 2 (MDM2) expression. SMEAF significantly increased the expression of the Bax protein resulting in a markedly elevated Bax/Bcl-2 ratio which may have triggered the mitochondrial apoptotic pathway, resulting in caspase-3/7 and caspase-9 activation.
  
  
  CONCLUSIONS
  These results suggested that SMEAF exerts its antitumor activity in HCT116 cells by activating proapoptotic signaling pathway through intracellular ROS formation triggering the mitochondrial-mediated pathway via p53 activation.
authors.affiliation: Biomolecular Research Group, Biochemistry Program, Institute of Biological Sciences, Faculty of Science, University of Malaya, 50603 Kuala Lumpur, Malaysia.
authors.forename: Bey Hing
authors.initials: BH
authors.lastname: Goh
authors.affiliation: Biomolecular Research Group, Biochemistry Program, Institute of Biological Sciences, Faculty of Science, University of Malaya, 50603 Kuala Lumpur, Malaysia.
authors.forename: Chim Kei
authors.initials: CK
authors.lastname: Chan
authors.affiliation: Biomolecular Research Group, Biochemistry Program, Institute of Biological Sciences, Faculty of Science, University of Malaya, 50603 Kuala Lumpur, Malaysia.
authors.forename: Muhamad Noor Alfarizal
authors.initials: MN
authors.lastname: Kamarudin
authors.affiliation: Biomolecular Research Group, Biochemistry Program, Institute of Biological Sciences, Faculty of Science, University of Malaya, 50603 Kuala Lumpur, Malaysia. Electronic address: habsah@um.edu.my.
authors.forename: Habsah
authors.initials: H
authors.lastname: Abdul Kadir
mesh_terms: D017209:Apoptosis / Q000187:drug effects / Q000502:physiology*; D015179:Colorectal Neoplasms / Q000378:metabolism*; D004305:Dose-Response Relationship, Drug; D045325:HCT116 Cells; D006801:Humans; D029582:Meliaceae; D008928:Mitochondria / Q000187:drug effects / Q000378:metabolism*; D010936:Plant Extracts / Q000302:isolation & purification / Q000494:pharmacology*; D017382:Reactive Oxygen Species / Q000378:metabolism; D012639:Seeds; D016159:Tumor Suppressor Protein p53 / Q000096:biosynthesis*; D015854:Up-Regulation / Q000187:drug effects / Q000502:physiology
chemical_list: D010936:Plant Extracts; D017382:Reactive Oxygen Species; D016159:Tumor Suppressor Protein p53
keywords: Apoptosis; Bax/Bcl-2; Caspase; ROS; Swietenia macrophylla; p53