Journal List > J Korean Surg Soc > v.77(3) > 1011001

Lee, Park, Park, Kim, Choi, Kim, Park, and Chong: Effects of Extremely Low Frequency Elecromagnetic Fields on Thyroid Carcinogenesis Induced by N-bis(2-hydroxypropyl)nitrosamine and Sulfadimethoxine



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.


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 p21WAF1/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.


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 p21WAF1/Cip1, was significantly increased in adenomas and carcinomas in ELF-EMF exposure group compared with the control group.


Exposure of ELF-EMF effects on chemically-induced rat thyroid carcinogenesis as results of altered increase of cellular proliferation, apoptosis, and cyclin D1 expression.

Figures and Tables

Fig. 1
In vivo extremely low frequency electromagnetic fields generator.
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).
Fig. 3
Immunohistochemical reactivity of Ki-67 (A), p21WAF1/Cip1 (B), cyclin D1 (C), and caspase 3 (D) expression (ABC, ×200).
Table 1
Thyroid lesions in rat after 12 weeks treated with N-bis (hydroxypropyl)nitrosamine and sulfadimethoxine

*ELF exposure = extremely low frequency exposure; Values are mean±SD.

Table 2
Ki-67 and apoptotic labeling index of the rat thyroid lesions

*ELF exposure = extremely low frequency exposure; Values are mean±SD.

Table 3
Cyclin D1 and p21WAF1/Cip1 protein labeling index of the rat thyroid lesions

*ELF exposure = extremely low frequency exposure; Values are mean±SD.

Table 4
Caspase 3 and p53 protein labeling index of the rat thyroid lesions

*ELF exposure = extremely low frequency exposure; Values are mean±SD.


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