Dose-Related Influence of Sodium Selenite on Apoptosis in Human Thyroid Follicles In Vitro Induced by Iodine, EGF, TGF-beta, and H2O2.
Apoptosis of thyroid follicular cells is induced by high doses of iodide, epidermal growth factor (EGF), transforming growth factor-beta (TGF-beta), as well as H2O2 and might be attenuated by antioxidants. Therefore, we examined the apoptotic index induced by these substances in selenium-treated vs untreated human thyroid follicular cells. Reconstituted human thyroid follicles were incubated with sodium selenite (10 or 100 nM) for 72 h; controls received none. The follicles were then distributed to 24-well plates and incubated with potassium iodide (5, 10, or 20 nM), EGF (5 ng/mL), TGF-beta (5 ng/mL), or H2O2 (100 muM). Apoptosis was determined by a mitochondrial potential assay and the number of apoptotic cells counted by two independent, experienced technicians and the glutathione peroxidase ( GPx) activity was determined. Asignificant increase of apoptic cells was obtained in control thyroid follicles treated with iodine (5, 10, or 20 muM), thyroidstimulating hormone (TSH) 1, or 10 mU/mL in combination with 5 and 10 muM iodine, EGF (5 ng/mL) and TGF-beta (5 ng/mL), or H2O2 (100 muM) (p < 0.001). In contrast, in thyroid follicles preincubated with 10 or 100 nM sodium selenite, the apoptototic index was identical to the basal rate. In H2O2-treated follicles, the apoptotic index was still significantly elevated but 50% lower compared to control cells. The GPx activity increased from 1.4 +/- 0.2 to 2.25 +/- 0.4 mU/mug DNA with 10 nMselenite and 2.6 + 0.4 mU/mug DNA with 100 nM selenite. Sodium selenite might increase the antioxidative potential in human thyroid follicles in vitro and therefore diminish the apoptosis induced by TGF-beta, EGF, iodide, and even H2O2.[1]References
- Dose-Related Influence of Sodium Selenite on Apoptosis in Human Thyroid Follicles In Vitro Induced by Iodine, EGF, TGF-beta, and H2O2. Lehmann, P., Rank, P., Hallfeldt, K.L., Krebs, B., G??rtner, R. Biological trace element research. (2006) [Pubmed]
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