A novel loss-of-function deletion in sodium/iodide symporter gene in follicular thyroid adenoma

Liang, Ji-An; Chen, Chun-Ping; Huang, Shin-Jer; Ho, Tin-Yun; Hsiang, Chien-Yun; Ding, Hueisch-Jy; Wu, Shih-Lu

doi:10.1016/j.canlet.2004.12.036

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Volume 230, Issue 1 , Pages 65-71, 8 December 2005

A novel loss-of-function deletion in sodium/iodide symporter gene in follicular thyroid adenoma

Ji-An Liang
- Departments of Radiation Therapy and Oncology, China Medical University Hospital, Taichung, Taiwan, ROC
Chun-Ping Chen
- Department of Medical Research, China Medical University Hospital, Taichung, Taiwan, ROC
Shin-Jer Huang
- Department of Surgery, China Medical University Hospital, Taichung, Taiwan, ROC
Tin-Yun Ho
- Institute of Chinese Medical Science, China Medical University, Taichung, Taiwan, ROC
Chien-Yun Hsiang
- Departments of Microbiology, China Medical University, Taichung, Taiwan, ROC
Hueisch-Jy Ding
- Department of Radiological Technology, I-Shou University, Kaohsiung, Taiwan, ROC
Shih-Lu Wu
- Department of Biochemistry, China Medical University, 91 Hsueh-Shih Road, Taichung 404, Taiwan, ROC
- Corresponding author. Tel.: +886 4 2205 3366x8610; fax: +886 4 2205 3764.

Received 20 September 2004; received in revised form 15 December 2004; accepted 18 December 2004.

Abstract

The sodium/iodide symporter (NIS) actively transports iodide into thyrocytes. However, in thyroid carcinoma, down-regulated or mis-targeted NIS expression is commonly found and usually correlates with tumor dedifferentiation and loss of radioiodine uptake capacity. In this study, we screened NIS genes of thyroid tumor tissues from three patients with thyroid carcinoma by using reverse transcription-polymerase chain reaction and nucleotide sequencing. We found a novel exon 6 deletion in NIS gene. We then examined the NIS gene from the blood of this patient. The nucleotide sequences of the flanking region of exon 6 were normal. By transient transfection and I-125 uptake assay, we found that the wild type NIS-expressing HepG2 cells accumulated six times more iodide than mutant and mock HepG2 cells. Our data demonstrated that the exon 6 deletion causes an iodide-trapping defect.

Keywords: Iodide transport defect, Sodium/iodide symporter, Thyroid carcinoma, I-125 uptake assay