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Background: Attention to the electromagnetic exposure as a targeted tumor therapy has been recently increasing. Objectives: The aim of the current study was to investigate the effect of continuous and discontinuous electromagnetic fields on cell viability as well as phosphatase and tensin homolog (PTEN) and circular (circ)-RNA CDR1as genes expression in the normal and gastric cancer (GC) cell lines. Methods: After preparing gastric cancer cell lines (AGS) and normal cells (HU02 line), they were exposed to magnetic flux densities of 0.25, 0.5, 1, and 2 mT continuously and discontinuously (1h on/1h off) for 18 hours. The 3-(4,5-dimethylthiazoyl-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay was used to evaluate cell viability. In addition, after designing the primers, the expression of the PTEN and circ-CDR1as genes was studied using the real-time polymerase chain reaction (real-time-PCR) technique. The results were analyzed using SPSS software version 25. Results: The exposed normal and tumor cells to discontinuous electromagnetic fields resulted in increasing of cell survival rate in both normal and tumor cells. In contrast, the exposure of continuous electromagnetic field showed no effect on the viability of the normal and tumor cells at intensities of 0.25, 0.5, and 1 mT. The electromagnetic field showed a significant effect on the expression of the circ-CDR1as gene and this effect depended on the intensity of the electromagnetic field used and the cell type. We have found that the activity of PTEN gene in the normal and tumor cells increased and decreased with increasing intensity of discontinuous electromagnetic field, respectively. Conclusions: In general, the effect of electromagnetic field on gastric cancer seems to depend on the kind of exposure as well as an extent of intensity and can be used for cancer therapeutic purposes. However, more research is needed on this subject.

: The biological effects of electromagnetic fields (EMF), in particular their beneficial or adverse impacts on the promotion and progression of cancer, have attracted considerable attention. C-Myc has a critical regulatory role in cell transformation and causes metabolic changes, that accompany malignant transformation. Observations have shown that c-Myc expression can be altered by circular RNAs (circRNA). In this study, the changes in the expression of c-Myc and circ-CCDC66 in the AGS cell line after the extremely low-frequency magnetic fields (ELF-MF) exposure were investigated. The AGS cells were exposed to different magnetic flux densities for 18 h, continuously and discontinuously (2h on/2h off). To evaluate the expression changes of c-Myc and circ-CCDC66 real-time PCR was used. The results showed that discontinuous magnetic fields could reduce c-Myc expression. Continuous exposure of 0.25 mT could reduce the c-Myc expression, but with increasing the magnetic flux density c-Myc was upregulated. The expression level of circ-CCDC66 decreased under exposure to continuous and discontinuous ELF-MFs. The difference between the results of c-Myc under the influence of magnetic fields may be described by the hypothesis of the window effect of the fields. Our results indicated that ELF-MFs can induce changes in c-Myc and circ-CCDC66 expression.

Background: In recent years, the relationship between cancer cells and electromagnetic radiation has received much attention. Objectives: The present study aimed to evaluate the effects of different intensities of electromagnetic fields on gastric cancer cell lines (AGS). Methods: After preparing AGS and Hu02 (normal) cell lines, they were exposed to magnetic flux densities of 0.25, 0.5, 1, and 2 millitesla (mT) for 18 h. The cell viability was studied by the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay. The expression levels of hes1 and hsa-circ-0068530 RNAs were studied by the quantitative Real-time-PCR technique. Results: The inhibition of gastric cancer cell line growth was observed under the influence of electromagnetic fields at different intensities. However, they did not affect the viability of normal cells. A sharp increase in the expression of hes1 and hsa-circ-0068530 genes was observed in normal cells exposed to 2 mT electromagnetic fields. Conclusions: In general, it can be concluded that the effect of electromagnetic fields on gastric cancer cells depends on their intensity. Magnetic flux densities of 0.25 and 0.5 mT had anti-cancer effects and magnetic flux density of 2 mT showed carcinogenic effects.