Growth Inhibition of Malignant Melanoma by Intermediate Frequency Alternating Electric Fields, and the Underlying Mechanisms

OBJECTIVE: This study investigated the antitumour effects of intermediate frequency alternating electric fields (IF-AEF) in a murine melanoma cell line (B16F10) and a mouse tumour model. METHODS: IF-AEF was applied at 100 kHz. Proliferation of B16F10 cells in vitro was assessed by the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide assay. IF-AEF was applied in vivo to mice bearing B16F10 tumours. Terminal deoxy nucleotidyl transferase-mediated dUTP nick end labelling (TUNEL) assay for apoptosis, and immunohistochemical detection of CD34 and vascular endothelial growth factor (VEGF), were performed. RESULTS: IF-AEF inhibited the proliferation of B16F10 cells in an electrical intensity and time-dependent manner. Treatment with IF-AEF for 7 days significantly inhibited the growth of tumours compared with untreated controls. IF-AEF induced apoptosis in vivo and reduced CD34-positive cell numbers; CD34 is a special marker of microvessel density. CONCLUSION: IF-AEF reduced microvessel density related to tumour growth and may serve as a therapeutic strategy for cancer treatment.