Tumor-treating fields in combination with sorafenib restrain the proliferation of liver cancer in vitro

Liver cancer is a common malignancy worldwide, with a poor prognosis and a high recurrence rate despite the available treatment methodologies. Tumor-treating fields (TTFields) have shown good preclinical and clinical results for improving the prognosis of patients with glioblastoma and malignant pleural mesothelioma. However, there is minimal evidence for the effect of TTFields on other cancer types. Thus, the present study aimed to investigate the therapeutic efficacy of TTFields in an in vitro model, and to further elucidate the underlying mechanisms. In the present study, two hepatocellular carcinoma (HCC) cell lines (Hep3B and HepG2) were treated with TTFields (intensity, 1.0 V/cm; frequency, 150 kHz) in order to determine the potential antitumor effects of this approach. TTFields significantly inhibited the proliferation and viability of HCC cell lines, as measured using Trypan blue and MTT assays, as well as colony formation in three-dimensional cultures. The TTFields also significantly inhibited the migration and invasion of HCC cells in Transwell chamber and wound-healing assays. Moreover, TTFields enhanced the production of reactive oxygen species in the cells and increased the proportion of apoptotic cells, as evidenced by increased caspase-3 activity, as well as PARP cleavage in western blotting experiments. All of these effects were increased following the application of TTFields in combination with the multi-kinase inhibitor sorafenib, which demonstrated a synergistic effect. Thus, to the best of our knowledge, these results demonstrate for the first time the potential of TTFields in improving the sensitivity of HCC cells to sorafenib, which may lay the foundation for future clinical trials for this combination treatment strategy.