Cellular Studies Of Extremely Low Frequency Electromagnetic Fields On Gene Mutations And Expression

Extremely low frequency (ELF) fields (>0 to 300 Hz) are one kind of electromagnetic fields, which are common used in people抯 daily life. Usually, ELF fields are produced by trains for public transport (16 2/3 to 50 or 60 Hz), any device involved in the generation, distribution or use of electric power, for example, high voltage power line and home appliances. With the development of electrical technology, the possible health hazard of exposure to ELF fields has become an issue of considerable public concern, particularly, the association between exposure to ELF fields and the risk of cancers. Lots of epidemiological studies have suggested an increased risk for cancers, especially leukemia and brain and breast cancer, with environmental ELF fields. However, there are also many inconsistent and contradictory reports. It is well known that many factors are involved in the carcinogenic effects of exposure to ELF fields, such as exposure time, effects of ELF fields alone, 搘indow effects?of ELF fields, combining effects with other physical factors, chemical factors orbiological factors. The meaning of 搘indow effects?is that 4 ELF fields have bioeffects only at the confined density or frequency. In order to clarify the carcinogenic effects of exposure to ELF fields, a lot of research work has been done, but because of methodological differences, it is far to draw a conclusion. Till now, little study has been done in China. Investigating the effects of exposure to ELF fields on gene mutations and gene expression is very important to estimate whether ELF fields have carcinogenic effects. Similarly, It is of great importance to understand the health hazards of exposure to ELF fields. Besides, our study also provides valuable information for government to establish safety criterion to ELF fields. In this study, human malignant glioma (M054), Chinese hamster ovary (CHO) and human breast cancer (MCF-7) cell lines were used. We examined the effects of long-term (8 days) exposure to 5 mT ELFMF on mutation induction and X-ray-induced mutations in M054 cells introduced with different mutant 1KB-a (a critical inhibitor of NF-KB) genes; Effects of exposure to ELF electric fields on hypoxanthine-guanine phosphoribosyl transferase (HPRT) gene mutations in CHO cells were observed by CHOIHIPRT mutation system; Cell cycle distribution, apoptosis and the expression of their related genes (p21, bax) were determined by the methods of P1 staining, western blotting and Annexin-V staining in MCF-7 cells following exposure to magnetic fields (60 Hz, 5 mT) alone or in combination with X-rays. In the respect of the effects of exposure to ELF magnetic fields on HPRT gene mutations in NF-w.B inhibited cells, an obvious increase in X-ray-induced mutations was observed after treatment with ELFMF in combination with X-irradiation in M054 cells with tyrosine mutant 1KB-a 5 gene other than with serine mutant 1KB-a gene or vector alone. Exposure to ELFMF alone increased mutations significantly in M054 cells with tyrosine mutant hcB-a gene. In the respect of gene mutations induced by exposure to ELF electric field (EF), we observed an increase in HPRT gene mutations in CHO cells after exposure to EF (10 V/rn, 60 Hz) for 10 h. The mutant frequency by EF-exposure was an approximate...