Pulsed Electromagnetic Field Enhances Caffeic Acid Phenethyl Ester-induced Death of MCF-7 Breast Cancer Cells

Caffeic acid phenethyl ester (CAPE) exerts anticancer effects against several cancer types, including breast cancer. Pulsed electromagnetic field (PEMF) improves the efficiency of some chemotherapeutic drugs. In this study, we examined the effects of PEMF stimulation on the anticancer activity of CAPE in MCF-7 breast cancer cells and the underlying signal transduction pathways.

MCF-7 cells were seeded and incubated for 24 h. Each of the drugs (5-fluorouracil, paclitaxel, gefitinib, or CAPE) was added to the cells on day 0. Then, cells were immediately stimulated with a 60-min PEMF session thrice a day (with 4-h interval between sessions) for 1-3 days. Cell death and viability were assessed by flow cytometry and trypan blue dye exclusion assay. Molecular mechanisms involved in cell death were confirmed by western blot assay.

Compared with treatment with CAPE alone, co-treatment with CAPE and PEMF more strongly reduced the viability of MCF-7 cells, further increased the percentage of the sub-G1 population, poly (ADP-ribose) polymerase (PARP) cleavage, activation of apoptotic caspases, up-regulation of pro-apoptotic proteins, such as Fas cell surface death receptor (FAS) and BCL2 associated X, apoptosis regulator (BAX), and reduced the expression of anti-apoptotic proteins, such as BCL-2 apoptosis regulator (BCL-2), MCL-1 apoptosis regulator, BCL-2 family member (MCL-1), and survivin. PEMF stimulation also increased CAPE-induced phosphorylation of p53, and inhibition of p53 partially restored the PEMF-reduced viability of CAPE-treated MCF-7 cells.

PEMF stimulation enhanced CAPE-induced cell death by activating p53, which regulates the expression of apoptosis-related molecules, subsequently activating the caspase-dependent apoptotic pathway in MCF-7 cells, suggesting that PEMF can be utilized as an adjuvant to enhance the effect of CAPE on breast cancer cells.