Modulation of thyroidal radioiodine uptake by theophylline

Background: We investigated whether theophylline has the potential to increase radioiodide uptake in nonthyroidal cancer cells. Materials and Methods: MCF-7 cells that express endogenous sodium=iodide symporter (NIS) and SNU-C5 cells adenovirally transduced with the human NIS gene (SNU-C5=NIS) were treated with 10 À7 -2Â10 À4 mol=L theophylline for 24 hours before incubation with 125 I, and then, radioiodide uptake and retention were measured. NIS expression was assessed by immunohistochemistry and Western blot analysis, using an antihuman NIS monoclonal antibody. Results: Theophylline at 10 À6 -2Â10 À4 mol=L significantly and dose dependently augmented radioiodide uptake in MCF-7 cells and at 10 À6 -10 À5 mol=L in SNU-C5=NIS cells, without affecting radioiodide efflux. Abrogation by KClO 4 À demonstrated that the effect of theophylline occurred through specific iodide transport. Immunohistochemistry revealed dose-dependent increases of NIS staining in MCF-7 and SNU-C5=NIS cells by 10

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Effects of Theophylline on Radioiodide Uptake in MCF-7 Breast Cancer and NIS Gene–Transduced SNU-C5 Colon Cancer Cells

Yoon

Park

Paik

et al. 2009

Cancer Biotherapy and Radiopharmaceuticals

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A Gamma Camera Re-Evaluation of Potassium Iodide Blocking Efficiency in Mice

Hammond

Bradley²,

Welsh³

et al. 2007

Health Physics

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The protection of the thyroid against radioiodine uptake has been an important safety concern for decades. After several studies examined potassium iodide blockade efficacy in the 1960's and 1970's, a standard dosage was prescribed by both the World Health Organization and the U.S. Food and Drug Administration. In this paper, we tested the effectiveness of a scaled version of that standard dosage in comparison to higher doses in mice. A novel gamma camera was employed with a high spatial resolution for precisely quantifying activity within the thyroid and a field of view large enough to image the entire mouse body. Thyroid and whole-body 125I biodistribution was analyzed immediately after exposure and 1 and 7 days later. It was found that 1 h after exposure five times the scaled human dose blocked thyroid uptake about 40% more effectively than the 1X scaled dose. Even after 1 d and 7 d, five times the recommended scaled human dose blocked approximately 10% more effectively than the 1X dose. These data suggest the need for continued evaluation of the effectiveness of KI as a blocking agent and the application of novel, non-invasive technologies to this important human health issue.

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Modulation of thyroidal radioiodine uptake by theophylline

Cited by 2 publications

References 25 publications

Effects of Theophylline on Radioiodide Uptake in MCF-7 Breast Cancer and NIS Gene–Transduced SNU-C5 Colon Cancer Cells

Effects of Theophylline on Radioiodide Uptake in MCF-7 Breast Cancer and NIS Gene–Transduced SNU-C5 Colon Cancer Cells

A Gamma Camera Re-Evaluation of Potassium Iodide Blocking Efficiency in Mice

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