Eliminating cancer stem cells can inhibit progression of residual hepatocellular carcinoma after radiofrequency ablation

Objectives: In this study, we aimed to examine the effects of Cancer Stem Cells (CSCs) on residual hepatocellular carcinoma (HCC) after radiofrequency ablation (RFA), and how to reduce the frequency of carcinoma cells with the CSCs phenotype in residual tumors after RFA.

Materials & methods: Two HCC cell lines were exposed to 43 °C for 30 min in vitro using a water bath. Cell cycle, EdU assays and plate colony assays were performed to evaluate the proliferation of HCC cells. Cell migration was determined using wound healing and Transwell assays. Sphere formation and in vivo limiting dilution assays were performed to evaluate stemness. In vivo, two tumor-bearing mice were used to evaluate residual tumor growth, and treatments included an extracellular signal-regulated kinase (ERK) inhibitor U0126 and salinomycin (Sal).

Results: In vitro, sublethal heat accelerated Cancer cell proliferation, migration, and stemness, and induced molecular changes of epithelial-mesenchymal transition (EMT), ERK, and the β-catenin pathway. ERK Inhibitor and Sal inhibited the proliferation, migration, and stemness of heat-treated HCC cells. The results showed that, in vivo, the ERK Inhibitor + Sal significantly inhibited the growth of residual tumors after incomplete RFA. Compared with incomplete RFA alone, EMT markers, ERK, and the β-catenin pathway were also significantly inhibited after treatment with ERK Inhibitor + Sal.

Conclusions: Incomplete RFA can accelerate cell proliferation, migration, and stemness in residual tumors. ERK Inhibitor combined with Sal could inhibit Cancer cell proliferation, migration, and stemness to synergically inhibit the progression of residual tumor.