Anti-tumor activity of sorafenib in a model of a pediatric hepatocellular carcinoma.

Background: Treatment outcome of children with pediatric hepatocellular carcinoma (pHCC) is poor. Therefore, we evaluated the tyrosine kinase inhibitor sorafenib in a model of pHCC.

Methods: Cell viability after treatment with sorafenib was evaluated in HC-AFW1 cells (pHCC) using MTT assay and compared to an adult HCC (aHCC) and two hepatoblastoma (HB) cell lines. ERK, pERK, E-cadherin, and vimentin expression were investigated using Western Blot. Sorafenib (60 mg/kg) was administered orally to NOD.Cg-Prkdcscid-IL2rgtmWjl/Sz mice bearing subcutaneous HC-AFW1-derived tumors. Tumor progression, viability, and vascularization were monitored by tumor volume, AFP levels, and CD31 immunostaining, respectively. Sensitization to sorafenib was evaluated using the β-catenin inhibitor ICG001.

Results: Sorafenib reduced cell viability in HC-AFW1 (IC50: 8 µM), comparable to HB cells, however less pronounced in aHCC cells (IC50: 23 µM). Sorafenib inhibited ERK signaling in both, HC-AFW1 cells and -xenografts. In vivo, sorafenib treatment only led to a moderate tumor growth inhibition, although significant reduction of vascularization and tumor growth kinetics was observed. Long-term treatment with sorafenib decreased E-cadherin, but showed no induction of vimentin expression. Combining sorafenib with a β-catenin inhibitor led to an additional reduction of cell viability.

Conclusion: Sorafenib together with inhibitors of the β-catenin pathway might be an effective tool in the treatment of pediatric HCC.