Low Pi stress enhances the sensitivity of hepatocellular carcinoma to sorafenib

Sorafenib is a tyrosine kinase inhibitor for the treatment of advanced-stage HCC; however, clinical trials of sorafenib failed to demonstrate long-term survival benefits due to drug resistance. Low Pi stress has been shown to inhibit tumor growth and the expression of multidrug resistance-associated proteins. In this study, we investigated the sensitivity of HCC to sorafenib under conditions of low Pi stress. As a result, we found that low Pi stress facilitated sorafenib-mediated suppression of migration and invasion of HepG-2 and Hepa1-6 cells by decreasing the phosphorylation or expression of AKT, Erk and MMP-9. Angiogenesis was inhibited due to decreased expression of PDGFR under low Pi stress. Low Pi stress also decreased the viability of sorafenibresistant cells by directly regulating the expression of AKT, HIF-1a and P62. In vivo drug sensitivity analysis in the four animal models showed a similar tendency that low Pi stress enhances sorafenib sensitivity in both the normal and drug-resistant models. Altogether, low Pi stress enhances the sensitivity of hepatocellular carcinoma to sorafenib and expands the indications for sevelamer.