J Korean Surg Soc.  2009 Sep;77(3):161-169. 10.4174/jkss.2009.77.3.161.

Effects of Extremely Low Frequency Elecromagnetic Fields on Thyroid Carcinogenesis Induced by N-bis(2-hydroxypropyl)nitrosamine and Sulfadimethoxine

• Lee SH
• Park YJ
• Park ES
• Kim YS
• Choi YS
• Kim BG
• Park SJ
• Chong SM

• KMID: 2004214
• DOI: http://doi.org/10.4174/jkss.2009.77.3.161

Abstract

PURPOSE
Long-term exposure to extremely low-frequency (60 Hz) electromagnetic fields (ELF-EMF) raises the questions of the induction of biological effects including tumorigenesis. One mechanism through which ELF-MFS could influence neoplastic development is the imbalance of cellular proliferation and cell apoptosis. The present study investigated the effect of ELF-EMF on chemically-induced thyroid carcinogenesis in a rat. METHODS: We examined cellular proliferation index measured by anti-Ki-67 antigen, apoptosis, apoptosis related proteins such as caspase 3 and p53, and cell cycle-related proteins (cyclin D1 and p21(WAF1/Cip1)). Forty Male F344 rats received a subcutaneous N-bis(2-hydroxypropyl)nitrosamine (DHPN, 2,800 mg/kg) injection, and 1 week later were allowed free access to drinking water containing sulfadimethoxine (0.1%) for 12 weeks. Twenty rats were exposed by ELF-EMF. During the carcinogenesis, sequential histological changes from hyperplasia, adenoma, and ultimately to overt carcinomas were noted. RESULTS: The exposure group of ELF-EMF, significantly increases the number size of carcinomas. Also, the proliferative and apoptotic indices were significantly increased in the ELF-EMF exposure group than in the control group. The caspase 3 protein expression did not show any significant changes between ELF-EMF group and control group. The p53 protein was not detected in both ELF-EMF exposure and control group. Among the cell cycle related proteins, cyclin D1, not p21(WAF1/Cip1), was significantly increased in adenomas and carcinomas in ELF-EMF exposure group compared with the control group. CONCLUSION: Exposure of ELF-EMF effects on chemically-induced rat thyroid carcinogenesis as results of altered increase of cellular proliferation, apoptosis, and cyclin D1 expression.

Keyword

Extremely low frequency magnetic field; Thyroid carcinogenesis; N-bis(2-hydroxypropyl)nitrosamine (DHPN); Apoptosis; Cell cycle-related proteins

MeSH Terms

Adenoma
Animals
Apoptosis
Caspase 3
Cell Cycle
Cell Proliferation
Cell Transformation, Neoplastic
Cyclin D1
Drinking Water
Electromagnetic Fields
Humans
Hyperplasia
Male
Nitrosamines
Proteins
Rats
Rats, Inbred F344
Sulfadimethoxine
Thyroid Gland
Caspase 3
Cyclin D1
Drinking Water
Nitrosamines
Proteins
Sulfadimethoxine

Figure

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  Fig. 1 In vivo extremely low frequency electromagnetic fields generator.

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  Fig. 2 N-bis(2-hydroxypropyl)nitrosamine and sulfadimethoxine induced rat thyroid lesions, showing follicular cell hyperplasia (A), adenoma (B), and carcinoma (C) (H&E, ×200).

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  Fig. 3 Immunohistochemical reactivity of Ki-67 (A), p21WAF1/Cip1 (B), cyclin D1 (C), and caspase 3 (D) expression (ABC, ×200).

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