Systems approaches to predict the sensitivity and to increase the efficacy of multikinase inhibitor, sorafenib, for the treatment of hepatocellular carcinoma

Abstract

Sorafenib is the only approved targeted therapy for hepatocellular carcinoma (HCC) but it has been known that its effect to patients’ survival gain is limited as varying over a wide range depending on patho-genetic conditions. Thus, predicting the response of sorafenib and enhancing the efficacy of sorafenib is essential for achieving efficient control of intractable HCCs. In this study, (1) to find out the action mechanism and the resistance mechanism of sorafenib, a systems approach by combining biochemical experimentation and mRNA microarray analysis was done with pathway network study to investigate the resistance mechanism and functional consequences of sorafenib. Analysis of sorafenib-induced mRNA changes in HCC cell lines by gene set based analysis methods was performed and it was found that, in the presence of sorafenib, proteotoxic stress module are activated, leading to apoptosis. Pathway network analyses showed that protein disulfide isomerase (PDI) attenuates such stress, thereby increases the resistance to sorafenib. Cell viability assay shows that adding more endoplasmic reticulum (ER) stress by combining PDI inhibitor can synergistically increase the efficacy of sorafenib in HCC cell lines, Which was confirmed in the mouse xenograft model. These results demonstrate that sorafenib sensitivity can be enhanced by adding more stress through a systems approach. (2) To discover biomarkers that can predict the response to sorafenib, transcriptome data from public database were analyzed and candidate molecule endothelin 1 (EDN1) was extracted. Its role in the resistance to sorafenib was investigated through in vitro shRNA and overexpression studies in HCC cell lines. Further, its predictive ability was validated using HCC patients’ tissues and clinical data and it was found that EDN1 is a novel resistant factor to sorafenib and a significant prognostic factor that contributes to clinical outcomes of HCC patients receiving sorafenib treatment.