Dual inhibition of Akt and c‐Met as a second‐line therapy following acquired resistance to sorafenib in hepatocellular carcinoma cells

Sorafenib displays a limited efficacy for advanced hepatocellular carcinoma (HCC). Some patients with HCC initially respond to sorafenib, but eventually succumb to the disease, indicating that the acquired resistance to sorafenib reduces its beneficial effects. No alternative drugs are available after the failure of sorafenib therapy. Therefore, investigation of the mechanisms underlying the acquired resistance and development of second‐line treatments for sorafenib‐resistant HCC are urgently required. In this study, sorafenib‐resistant HCC cells generated from sorafenib‐sensitive human HCC cells were shown to overproduce hepatocyte growth factor (HGF) and overexpress c‐Met kinase and its phosphorylated form, leading to the activation of Akt and ERK (extracellular signaling‐regulated kinase) pathways. Use of specific c‐Met inhibitors enhanced the effects of sorafenib by inhibiting the growth of sorafenib‐resistant HCC cells. Akt inhibitors, a class of second‐line therapeutic drugs under investigation for treating HCC in clinical trials, enhanced the effects of sorafenib, but also activated the c‐Met pathway in sorafenib‐resistant cells. Dual inhibition of Akt and c‐Met by their respective inhibitors, MK2206 and capmatinib, additively or synergistically suppressed sorafenib‐resistant HCC cells in vitro and sorafenib‐resistant HCC xenografts in mice. The anticancer activities of MK2206 mainly rely on its ability to induce cell apoptosis and autophagic death, while capmatinib treatment leads to cell cycle arrest at phase G1. These results provide strong evidence for further investigation on the clinical utility of dual inhibition of Akt and c‐Met, particularly MK2206 and capmatinib, as a second‐line therapy for advanced HCC that has acquired resistance to sorafenib.