Epithelial-to-mesenchymal transition and integrin-linked kinase mediate sensitivity to epidermal growth factor receptor inhibition in human hepatoma cells

Hepatocellular carcinoma (HCC) is associated with a poor prognosis due to late diagnoses and a lack of effective treatment options. Epidermal growth factor receptor (EGFR)-targeted therapies have been effective in other cancers. However, erlotinib and cetuximab have shown only modest efficacy in clinical trials of HCC. We examined epithelial-to-mesenchymal transition (EMT) as a determinant of sensitivity of HCC to EGFR inhibitors. A panel of 12 human hepatoma cell lines were classified as epithelial or mesenchymal based on their expression of E-cadherin and vimentin. The resulting classification correlated with a previous microarray analysis of human hepatoma cell lines whereby the mesenchymal cell lines were shown to have increased expression of genes involved in metastasis and invasion. Sensitivity to erlotinib, gefitinib, and cetuximab was assessed and the epithelial cell lines were found to be significantly more susceptible to all three agents. Analysis of the EGFR pathway showed that EMT status was independent of EGFR expression or downstream extracellular signal-regulated kinase activation and only the epithelial cell lines expressed ErbB3. Interestingly, mesenchymal cells resistant to EGFR inhibitors had increased AKT and signal transducer and activator of transcription-3 activation through elevated expression of integrin-linked kinase (ILK). Mesenchymal cell lines were therefore experimentally transformed with kinase-inactive ILK (KI-ILK) with a resulting decrease in ILK activity and activation of AKT. KI-ILK transformants showed increased sensitivity to EGFR inhibitors both in vitro and in an in vivo xenograft model. These data suggest that EMT predicts HCC sensitivity to EGFR-targeted therapies and that ILK is a novel target to overcome HCC resistance to EGFR inhibition.