title: Novel in silico-designed estradiol analogues are cytotoxic to a multidrug-resistant cell line at nanomolar concentrations.
abstract: OBJECTIVE
  2-Methoxyestradiol (2ME) is a promising anti-cancer agent that disrupts the integrity and dynamics of the spindle network. In order to overcome the pharmacokinetic constraints of this compound, a panel of sulphamoylated estradiol analogues were in silico-designed by our laboratory. In this study, we analysed the potential of each analogue to induce cell death on a panel of cancer cell lines. Moreover, the mechanism of action of the most effective compounds was determined.
  
  
  METHODS
  Cytotoxicity screening of the compounds and intermediates was performed on five different cancer cell lines to determine IG50 values. An in vitro tubulin polymerization assay was done to determine the effect of the drugs on tubulin polymerization while their intracellular effects on the microtubule network were assessed by immunofluorescence microscopy.
  
  
  RESULTS
  IG50 calculations showed that the sulphamoylated analogues induce cytotoxicity at nanomolar concentrations in all cell lines, including the P-glycoprotein pump overexpressing multidrug-resistant uterine sarcoma cell line. The non-sulphamoylated compounds were only cytotoxic at micromolar ranges, if at all. The sulphamoylated compounds inhibited pure tubulin polymerization in a dose-dependent manner and induced microtubule destruction in cells after 24-h exposure.
  
  
  CONCLUSIONS
  Results revealed that the novel sulphamoylated 2ME derivatives have potential as anti-cancer drugs, possibly even against chemoresistant cancer cells. These compounds disrupt the intracellular microtubule integrity which leads to mitotic block of the cells.
authors.affiliation: Department of Physiology, Faculty of Health Sciences, University of Pretoria, Private Bag X323, Arcadia, Pretoria, Gauteng, 0007, South Africa, joji.theron@up.ac.za.
authors.forename: Anne
authors.initials: A
authors.lastname: Theron
authors.forename: Renaud
authors.initials: R
authors.lastname: Prudent
authors.forename: Elsie
authors.initials: E
authors.lastname: Nolte
authors.forename: Iman
authors.initials: I
authors.lastname: van den Bout
authors.forename: Rivak
authors.initials: R
authors.lastname: Punchoo
authors.forename: Sumari
authors.initials: S
authors.lastname: Marais
authors.forename: Peet
authors.initials: P
authors.lastname: du Toit
authors.forename: Yvette
authors.initials: Y
authors.lastname: Hlophe
authors.forename: Dirk
authors.initials: D
authors.lastname: van Papendorp
authors.forename: Laurence
authors.initials: L
authors.lastname: Lafanechère
authors.forename: Annie
authors.initials: A
authors.lastname: Joubert
mesh_terms: D000077584:2-Methoxyestradiol; D045744:Cell Line, Tumor; D002470:Cell Survival / Q000187:drug effects; D015195:Drug Design; D018432:Drug Resistance, Multiple / Q000187:drug effects*; D019008:Drug Resistance, Neoplasm / Q000187:drug effects*; D004354:Drug Screening Assays, Antitumor; D004958:Estradiol / Q000031:analogs & derivatives* / Q000627:therapeutic use*; D004967:Estrogens / Q000627:therapeutic use*; D006801:Humans; D008870:Microtubules / Q000187:drug effects / Q000648:ultrastructure; D014404:Tubulin / Q000378:metabolism
chemical_list: D004967:Estrogens; D014404:Tubulin; D004958:Estradiol; D000077584:2-Methoxyestradiol