Molecular mechanisms underlying antiproliferative and differentiating responses of hepatocarcinoma cells to subthermal electric stimulation

PLoS One. 2014 Jan 8;9(1):e84636. doi: 10.1371/journal.pone.0084636. eCollection 2014.


Capacitive Resistive Electric Transfer (CRET) therapy applies currents of 0.4-0.6 MHz to treatment of inflammatory and musculoskeletal injuries. Previous studies have shown that intermittent exposure to CRET currents at subthermal doses exert cytotoxic or antiproliferative effects in human neuroblastoma or hepatocarcinoma cells, respectively. It has been proposed that such effects would be mediated by cell cycle arrest and by changes in the expression of cyclins and cyclin-dependent kinase inhibitors. The present work focuses on the study of the molecular mechanisms involved in CRET-induced cytostasis and investigates the possibility that the cellular response to the treatment extends to other phenomena, including induction of apoptosis and/or of changes in the differentiation stage of hepatocarcinoma cells. The obtained results show that the reported antiproliferative action of intermittent stimulation (5 m On/4 h Off) with 0.57 MHz, sine wave signal at a current density of 50 µA/mm(2), could be mediated by significant increase of the apoptotic rate as well as significant changes in the expression of proteins p53 and Bcl-2. The results also revealed a significantly decreased expression of alpha-fetoprotein in the treated samples, which, together with an increased concentration of albumin released into the medium by the stimulated cells, can be interpreted as evidence of a transient cytodifferentiating response elicited by the current. The fact that this type of electrical stimulation is capable of promoting both, differentiation and cell cycle arrest in human cancer cells, is of potential interest for a possible extension of the applications of CRET therapy towards the field of oncology.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Apoptosis
  • Biomarkers, Tumor / metabolism
  • Carcinoma, Hepatocellular / metabolism
  • Carcinoma, Hepatocellular / pathology*
  • Carcinoma, Hepatocellular / therapy
  • Cell Differentiation*
  • Cell Proliferation
  • Electric Stimulation Therapy*
  • Gene Expression Regulation, Neoplastic
  • Hep G2 Cells
  • Humans
  • Intracellular Space / metabolism
  • Liver Neoplasms / metabolism
  • Liver Neoplasms / pathology*
  • Liver Neoplasms / therapy
  • Proto-Oncogene Proteins c-bcl-2
  • Serum Albumin / metabolism
  • Temperature*
  • Tumor Suppressor Protein p53 / metabolism
  • alpha-Fetoproteins / metabolism


  • Biomarkers, Tumor
  • Proto-Oncogene Proteins c-bcl-2
  • Serum Albumin
  • Tumor Suppressor Protein p53
  • alpha-Fetoproteins

Grant support

This work was financially supported by Fundación para la Investigación Biomédica del Hospital Ramón y Cajal, through Project FiBio-HRC No. 2006/0158. The funder had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.