The role of iodine and delta-iodolactone in growth and apoptosis of malignant thyroid epithelial cells and breast cancer cells

Hormones (Athens). Jan-Mar 2010;9(1):60-6. doi: 10.14310/horm.2002.1254.

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.

Conclusion: 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.

Publication types

  • Comparative Study

MeSH terms

  • Antineoplastic Agents / chemical synthesis
  • Antineoplastic Agents / pharmacology*
  • Apoptosis / drug effects*
  • Arachidonic Acids / chemical synthesis
  • Arachidonic Acids / pharmacology*
  • Breast Neoplasms / pathology*
  • Cell Line, Tumor
  • Cell Proliferation / drug effects
  • Dose-Response Relationship, Drug
  • Epithelial Cells / drug effects
  • Female
  • Humans
  • Iodine / pharmacology*
  • Membrane Potential, Mitochondrial / drug effects
  • Potassium Iodide / pharmacology*
  • Thyroid Neoplasms / pathology*

Substances

  • 6-iodo-5-hydroxy-eicosatrienoic acid, delta-lactone
  • Antineoplastic Agents
  • Arachidonic Acids
  • Potassium Iodide
  • Iodine