Evaluation of transcriptional activity of the oestrogen receptor with sodium iodide symporter as an imaging reporter gene.

Abstract

BACKGROUND:

Oestrogen receptors are ligand-dependent transcription factors whose activity is modulated either by oestrogens or by an alternative signalling pathway. Oestrogen receptors interact via a specific DNA-binding domain, the oestrogen responsive element (ERE), in the promoter region of sensitive genes. This binding leads to an initiation of gene expression and hormonal effects.

OBJECTIVE:

To determine the transcriptional activity of the oestrogen receptor, we developed a molecular imaging system using sodium iodide symporter (NIS) as a reporter gene.

METHODS:

The NIS reporter gene was placed under the control of an artificial ERE derived from pERE-TA-SEAP and named as pERE-NIS. pERE-NIS was transferred to MCF-7, human breast cancer cells, which highly expressed oestrogen receptor-alpha with lipofectamine. Stably expressing cells were generated by selection with G418 for 14 days. After treatment of 17beta-oestradiol and tamoxifen with serial doses, the (125)I uptake was measured for the determination of NIS expression. The inhibition of NIS activity was performed with 50 micromol x l(-1) potassium perchlorate.

RESULTS:

The MCF7/pERE-NIS treated with 17beta-oestradiol accumulated (125)I up to 70-80% higher than did non-treated cells. NIS expression was increased according to increasing doses of 17beta-oestradiol. MCF7/pERE-NIS treated with tamoxifen also accumulated (125)I up to 50% higher than did non-treated cells. Potassium perchlorate completely inhibited (125)I uptake. When MDA-MB231 cells, the oestrogen receptor-negative breast cancer cells, were transfected with pERE-NIS, (125)I uptake of MDA-MB-231/pERE-NIS did not increase.

CONCLUSION:

This pERE-NIS reporter system is sufficiently sensitive for monitoring transcriptional activity of the oestrogen receptor. Therefore, cis-enhancer reporter systems with ERE will be applicable to the development of a novel selective oestrogen receptor modulator with low toxicity and high efficacy.

• Authors: Joo Hyun Kang, June-Key Chung, Yong Jin Lee, Kwang Il Kim, Jae Min Jeong, Dong Soo Lee, Myung Chul Lee
• Journal: Nuclear medicine communications (Nucl Med Commun) Vol. 27 Issue 10 Pg. 773-7 (Oct 2006) ISSN: 0143-3636 [Print] England
• PMID: 16969258 (Publication Type: Journal Article, Research Support, Non-U.S. Gov't)

Chemical References

• Iodine Radioisotopes
• Receptors, Estrogen
• Symporters
• Tamoxifen
• Estradiol
• sodium-iodide symporter
• DNA

Topics

• Breast Neoplasms (metabolism)
• Cell Line, Tumor
• DNA (chemistry)
• Estradiol (pharmacology)
• Genes, Reporter
• Humans
• Iodine Radioisotopes (pharmacology)
• Protein Binding
• Radionuclide Imaging (instrumentation, methods)
• Receptors, Estrogen (biosynthesis, genetics)
• Response Elements
• Symporters (chemistry, metabolism)
• Tamoxifen (pharmacology)
• Transcription, Genetic