Introduction: The extremely-low frequency electromagnetic field (ELFEMF) has been proposed for use in cancer therapy since it was found that magnetic waves interfere with many biological processes. Gold nanoparticles (Au-NPs) have been widely used for drug delivery during cancer in vitro studies due to their low cytotoxity and high biocompatibility. The electroporation of cancer cells in a presence of Au-NPs (EP Au-NPs) can induce cell apoptosis, alterations of cell cycle profile and morphological changes. The impact of ELFEMF and EP Au-NPs on morphology, cell cycle and activation of apoptosis-associated genes on Hep-2 laryngeal cancer cell line has not been studied yet.
Materials and methods: ELFEMF on Hep-2 cells were carried out using four different conditions: 25/50 mT at 15/30 min, while Au-NPs were used as direct contact (DC) or with electroporation (EP, 10 pulses at 200V, equal time intervals of 4 sec). MTT assay was used to check the toxicity of DC Au-NPs. Expression of CASP3, P53, BAX and BCL2 genes was quantified using qPCR. Cell cycle was analyzed by flow cytometry. Hematoxylin and eosin (HE) staining was used to observe cell morphology.
Results: Calculated IC50 of DC Au-NPs 24.36 μM (4.79 μg/ml) and such concentration was used for further DC and EP AuNPs experiments. The up-regulation of pro-apoptotic genes (CASP3, P53, BAX) and decreased expression of BCL2, respectively, was observed for all analyzed conditions with the highest differences for EP AuNPs and ELFEMF 50 mT/30 min in comparison to control cells. The highest content of cells arrested in G2/M phase was observed in ELFEMF-treated cells for 30 min both at 25 or 50 mT, while the cells treated with EP AuNPs or ELFEMF 50 mT/15 min showed highest ratios of apoptotic cells. HE staining of electroporated cells and cells exposed to ELFEMF's low and higher frequencies for different times showed nuclear pleomorphic cells. Numerous apoptotic bodies were observed in the irregular cell membrane of neoplastic and necrotic cells with mixed euchromatin and heterochromatin.
Conclusions: Our observations indicate that treatment of Hep-2 laryngeal cancer cells with ELFEMF for 30 min at 25-50 mT and EP Au-NPs can cause cell damage inducing apoptosis and cell cycle arrest.
Keywords: Hep-2 cells; apoptosis; electroporation; extremely-low frequency electromagnetic field; gold nanoparticles; qPCR.