title: Cytotoxicity and modes of action of five Cameroonian medicinal plants against multi-factorial drug resistance of tumor cells.
abstract: BACKGROUND
  Beilschmiedia acuta Kosterm, Clausena anisata (Willd) Hook, Fagara tessmannii Engl., Newbouldia laevis Seem., and Polyscias fulva (Hiern) Harms. are medicinal plants used in Cameroonian traditional medicine in the treatment of various types of cancers. The present study aims at investigating 11 methanolic extracts from the above Cameroonian medicinal plants on a panel of human cancer cell lines, including various drug-resistant phenotypes. Possible modes of action were analyzed for two extracts from Beilschmiedia acuta and Polyscia fulva and alpha-hederin, the representative constituent of Polyscia fulva.
  
  
  METHODS
  Cytotoxicity was determined using a resazurin assay. Cell cycle, apoptosis, mitochondrial membrane potential (MMP), and reactive oxygen species (ROS) were measured by flow cytometry. Cellular response to alpha-hederin was investigated by a mRNA microarray approach.
  
  
  RESULTS
  Prescreening of extracts (40µg/mL) showed that three of eleven plant extracts inhibited proliferation of CCRF-CEM cells by more than 50%, i.e. BAL (73.65%), the bark extract of Beilschmiedia acuta (78.67%) and PFR (68.72%). Subsequent investigations revealed IC50 values below or around 30µg/mL of BAL and PFR in 10 cell lines, including drug-resistant models, i.e. P-glycoprotein-overexpressing CEM/ADR5000, breast cancer resistance protein-transfected MDA-MB-231-BCRP, TP53 knockout cells (HCT116 p53(-/-)), and mutation-activated epidermal growth factor receptor-transfected U87MG.ΔEGFR cells. IC50 values below 5µg/mL of BAL were obtained for HCT116 (p53(-/-)) cells. IC50 values below 10µM of alpha-hederin were found for sensitive CCRF-CEM and multidrug-resistant CEM/ADR5000 cells. The BAL and PFR extracts induced cell cycle arrest between G0/G1 and S phases. PFR-induced apoptosis was associated with increased ROS generation and MMP breakdown. Microarray-based cluster analysis revealed a gene expression profile that predicted cellular response to alpha-hederin.
  
  
  CONCLUSIONS
  BAL, PFL and alpha-hederin, an exemplarily taken constituent of Beilschmiedia acuta and Polyscia fulva extracts revealed cytotoxicity towards cancer cell lines. Hence, Beilschmiedia acuta and Polyscia fulva may be valuable to develop drugs against otherwise drug-resistant cancer cells.
authors.affiliation: Department of Pharmaceutical Biology, Institute of Pharmacy and Biochemistry, University of Mainz, Staudinger Weg 5, 55128 Mainz, Germany; Department of Biochemistry, Faculty of Science, University of Dschang, Dschang, Cameroon.
authors.forename: Victor
authors.initials: V
authors.lastname: Kuete
authors.affiliation: Department of Biochemistry, Faculty of Science, University of Dschang, Dschang, Cameroon.
authors.forename: Simplice B
authors.initials: SB
authors.lastname: Tankeo
authors.affiliation: Department of Pharmaceutical Biology, Institute of Pharmacy and Biochemistry, University of Mainz, Staudinger Weg 5, 55128 Mainz, Germany.
authors.forename: Mohamed E M
authors.initials: ME
authors.lastname: Saeed
authors.affiliation: Department of Pharmaceutical Biology, Institute of Pharmacy and Biochemistry, University of Mainz, Staudinger Weg 5, 55128 Mainz, Germany.
authors.forename: Benjamin
authors.initials: B
authors.lastname: Wiench
authors.affiliation: Department of Organic Chemistry, Faculty of Science, University of Dschang, Dschang, Cameroon.
authors.forename: Pierre
authors.initials: P
authors.lastname: Tane
authors.affiliation: Department of Pharmaceutical Biology, Institute of Pharmacy and Biochemistry, University of Mainz, Staudinger Weg 5, 55128 Mainz, Germany. Electronic address: efferth@uni-mainz.de.
authors.forename: Thomas
authors.initials: T
authors.lastname: Efferth
mesh_terms: D000972:Antineoplastic Agents, Phytogenic / Q000008:administration & dosage / Q000494:pharmacology*; D017209:Apoptosis / Q000187:drug effects; D002163:Cameroon; D059447:Cell Cycle Checkpoints / Q000187:drug effects; D045744:Cell Line, Tumor; D019008:Drug Resistance, Neoplasm; D006801:Humans; D020128:Inhibitory Concentration 50; D053078:Membrane Potential, Mitochondrial / Q000187:drug effects; D009369:Neoplasms / Q000188:drug therapy* / Q000473:pathology; D010936:Plant Extracts / Q000008:administration & dosage / Q000494:pharmacology*; D010946:Plants, Medicinal / Q000737:chemistry*
chemical_list: D000972:Antineoplastic Agents, Phytogenic; D010936:Plant Extracts
keywords: Apoptosis; Beilschmiedia acuta; Cytotoxicity; Microarrays; Mode of action; Polyscias fulva