title: Cytotoxicity of the indole alkaloid reserpine from Rauwolfia serpentina against drug-resistant tumor cells.
abstract: BACKGROUND
  The antihypertensive reserpine is an indole alkaloid from Rauwolfia serpentina and exerts also profound activity against cancer cells in vitro and in vivo. The present investigation was undertaken to investigate possible modes of action to explain its activity toward drug-resistant tumor cells.
  
  
  METHODS
  Sensitive and drug-resistant tumor cell lines overexpressing P-glycoprotein (ABCB1/MDR1), breast cancer resistance protein (ABCG2/BCRP), mutation-activated epidermal growth factor receptor (EGFR), wild-type and p53-knockout cells as well as the NCI panel of cell lines from different tumor origin were analyzed. Reserpine's cytotoxicity was investigated by resazurin and sulforhodamine assays, flow cytometry, and COMPARE and hierarchical cluster analyses of transcriptome-wide microarray-based RNA expressions.
  
  
  RESULTS
  P-glycoprotein- or BCRP overexpressing tumor cells did not reveal cross-resistance to reserpine. EGFR-overexpressing cells were collateral sensitive and p53- Knockout cells cross-resistant to this drug compared to their wild-type parental cell lines. Reserpine increased the uptake of doxorubicin in P-glycoprotein-overexpressing cells, indicating that reserpine inhibited the efflux function of P-glycoprotein. Using molecular docking, we found that reserpine bound with even higher binding energy to P-glycoprotein and EGFR than the control drugs verapamil (P-glycoprotein inhibitor) and erlotinib (EGFR inhibitor). COMPARE and cluster analyses of microarray data showed that the mRNA expression of a panel of genes predicted the sensitivity or resistance of the NCI tumor cell line panel with statistical significance. The genes belonged to diverse pathways and biological functions, e.g. cell survival and apoptosis, EGFR activation, regulation of angiogenesis, cell mobility, cell adhesion, immunological functions, mTOR signaling, and Wnt signaling.
  
  
  CONCLUSIONS
  The lack of cross-resistance to most resistance mechanisms and the collateral sensitivity in EGFR-transfectants compared to wild-type cells speak for a promising role of reserpine in cancer chemotherapy. Reserpine deserves further consideration for cancer therapy in the clinical setting.
authors.affiliation: Department of Pharmaceutical Biology, Institute of Pharmacy and Biochemistry, Johannes Gutenberg University of Mainz, Staudinger Weg 5, 55128 Mainz, Germany.
authors.forename: Sara A A
authors.initials: SA
authors.lastname: Abdelfatah
authors.affiliation: Department of Pharmaceutical Biology, Institute of Pharmacy and Biochemistry, Johannes Gutenberg 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: D018435:ATP Binding Cassette Transporter, Subfamily B / Q000378:metabolism; D000070997:ATP Binding Cassette Transporter, Subfamily G, Member 2; D018528:ATP-Binding Cassette Transporters / Q000378:metabolism; D000972:Antineoplastic Agents, Phytogenic / Q000494:pharmacology*; D045744:Cell Line, Tumor; D004317:Doxorubicin / Q000494:pharmacology; D018432:Drug Resistance, Multiple / Q000187:drug effects*; D019008:Drug Resistance, Neoplasm / Q000187:drug effects*; D066246:ErbB Receptors / Q000378:metabolism; D055786:Gene Knockout Techniques; D006801:Humans; D062105:Molecular Docking Simulation; D009363:Neoplasm Proteins / Q000378:metabolism; D011926:Rauwolfia / Q000737:chemistry*; D012110:Reserpine / Q000494:pharmacology*; D016159:Tumor Suppressor Protein p53 / Q000235:genetics / Q000378:metabolism
chemical_list: C513055:ABCB1 protein, human; C116614:ABCG2 protein, human; D018435:ATP Binding Cassette Transporter, Subfamily B; D000070997:ATP Binding Cassette Transporter, Subfamily G, Member 2; D018528:ATP-Binding Cassette Transporters; D000972:Antineoplastic Agents, Phytogenic; D009363:Neoplasm Proteins; C495901:TP53 protein, human; D016159:Tumor Suppressor Protein p53; D004317:Doxorubicin; D012110:Reserpine; C512478:EGFR protein, human; D066246:ErbB Receptors
keywords: ABC-transporter; Cluster analysis; Collateral sensitivity; Molecular docking; Pharmacogenomics; Reserpine