The role of iodine and delta-iodolactone in growth and apoptosis of malignant thyroid epithelial cells and breast cancer cells.
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.
Gärtner
Roland
R
Department of Endocrinology, University of Munich, Germany. roland.gaertner@med.uni.muenchen.de
Rank
Petra
P
Ander
Birgit
B
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*
C026915:6-iodo-5-hydroxy-eicosatrienoic acid, delta-lactone; D000970:Antineoplastic Agents; D001095:Arachidonic Acids; D011193:Potassium Iodide; D007455:Iodine