title: The role of iodine and delta-iodolactone in growth and apoptosis of malignant thyroid epithelial cells and breast cancer cells.
abstract: OBJECTIVE
  As we previously demonstrated, the inhibitory effect of iodine on thyroid cell growth is mediated by iodolactones, especially 6-iodo-5-hydroxy-eicosatrienoic acid (delta-iodolactone). In this communication we compare the effect of iodide, molecular iodine and delta-iodolactone on growth inhibition and apoptosis on three human thyroid carcinoma cell lines (B-CPAP cells, FTC-133 cells and 8505C cells) as well as on human breast cancer cells (MCF 7).
  
  
  METHODS
  Thyroid carcinoma cells were cultured in Dulbecco's modified Eagle's medium (DMEM) and MCF 7 cells in Rowswell Park Memorial Institute (RPMI) culture medium, both containing 10% (v/v) Fetal Calf Serum (FCS), until they were confluent. Around 2000 cells were then distributed in 12-well plates and grown for 48 h in either DMEM (thyroid cancer cells) or in RPMI medium (MCF 7 cells) both containing 5% FCS. Thereafter, different concentrations of iodide, iodine or delta-iodolactone were added for 24 h. Growth rate was estimated by cell counting in a Coulter Counter adapted for epithelial cells. Apoptosis was determined by a mitochondrial potential assay.
  
  
  RESULTS
  The growth rate of B-CPAP cells was unaffected by iodide, but was reduced by high concentreations of molecular iodine (100 and 500 microM). However, delta-iodolactone significantly reduced cell proliferation already with low concentrations (5 microM and 10 microM) and further in a dose-dependent manner up to 82%. FTC-133 and 8505C cells were unaffected by iodide, iodine or delta-iodolactone. In contrast, in MCF 7 cells, molecular iodine (100 microM) inhibited growth from 100% to 83% but delta-iodolactone (1, 5 and 10 microM) dose-dependently decreased growth rate from 100% to 82% and 62%, respectively. The inhibition of growth was through apoptosis, and not necrosis, as the amount of apoptotic cells corresponded to the growth inhibition.
  
  
  CONCLUSIONS
  delta-Iotaodolactone seems to be the main iodocompound which can inhibit growth and induce apoptosis in B-CPAP cells as well as in MCF 7 breast cancer cells.
authors.affiliation: Department of Endocrinology, University of Munich, Germany. roland.gaertner@med.uni.muenchen.de
authors.forename: Roland
authors.initials: R
authors.lastname: Gärtner
authors.forename: Petra
authors.initials: P
authors.lastname: Rank
authors.forename: Birgit
authors.initials: B
authors.lastname: Ander
mesh_terms: D000970:Antineoplastic Agents / Q000138:chemical synthesis / Q000494:pharmacology*; D017209:Apoptosis / Q000187:drug effects*; D001095:Arachidonic Acids / Q000138:chemical synthesis / Q000494:pharmacology*; D001943:Breast Neoplasms / Q000473:pathology*; D045744:Cell Line, Tumor; D049109:Cell Proliferation / Q000187:drug effects; D004305:Dose-Response Relationship, Drug; D004847:Epithelial Cells / Q000187:drug effects; D005260:Female; D006801:Humans; D007455:Iodine / Q000494:pharmacology*; D053078:Membrane Potential, Mitochondrial / Q000187:drug effects; D011193:Potassium Iodide / Q000494:pharmacology*; D013964:Thyroid Neoplasms / Q000473:pathology*
chemical_list: C026915:6-iodo-5-hydroxy-eicosatrienoic acid, delta-lactone; D000970:Antineoplastic Agents; D001095:Arachidonic Acids; D011193:Potassium Iodide; D007455:Iodine