Inhibition of Akt reverses the acquired resistance to sorafenib by switching protective autophagy to autophagic cell death in hepatocellular carcinoma.
Sorafenib is the standard first-line systemic drug for advanced hepatocellular carcinoma (HCC), but the acquired resistance to sorafenib results in limited benefits. Activation of Akt is thought to be responsible for mediating the acquired resistance to sorafenib. The present study aims to examine the underlying mechanism and seek potential strategies to reverse this resistance. Two sorafenib-resistant HCC cell lines, which had been established from human HCC HepG2 and Huh7 cells, were refractory to sorafenib-induced growth inhibition and apoptosis in vitro and in vivo. Sustained exposure to sorafenib activated Akt via the feedback loop of mTOR but independent of protein phosphatase 2A in HCC cells. Autophagy participated in the resistance to sorafenib as inhibition of autophagy reduced the sensitivity of sorafenib-resistant HCC cells to sorafenib, whereas activation of autophagy by rapamycin had the opposite effect. However, rapamycin did not show a synergistic effect with sorafenib to inhibit cell proliferation, while it also activated Akt via a feedback mechanism in sorafenib-resistant HCC cells. Inhibition of Akt reversed the acquired resistance to sorafenib by switching autophagy from a cytoprotective role to a death-promoting mechanism in the sorafenib-resistant HCC cells. Akt inhibition by GDC0068 synergized with sorafenib to suppress the growth of sorafenib-resistant HCC tumors that possessed the sorafenib-resistant feature in vivo. The results have provided evidence for clinical investigation of GDC0068, a novel ATP-competitive pan-Akt inhibitor, as the second-line treatment after the failure of sorafenib-medicated molecular targeted therapy for advanced HCC.
Authors' Affiliations: The Hepatosplenic Surgery Center, Department of General Surgery, the First Affiliated Hospital of Harbin Medical University; and Departments of Gastroenterology and General Surgery, the Fourth Affiliated Hospital of Harbin Medical University, Harbin, China.
Bo
B
Zhai
Authors' Affiliations: The Hepatosplenic Surgery Center, Department of General Surgery, the First Affiliated Hospital of Harbin Medical University; and Departments of Gastroenterology and General Surgery, the Fourth Affiliated Hospital of Harbin Medical University, Harbin, China.
Fengli
F
Hu
Authors' Affiliations: The Hepatosplenic Surgery Center, Department of General Surgery, the First Affiliated Hospital of Harbin Medical University; and Departments of Gastroenterology and General Surgery, the Fourth Affiliated Hospital of Harbin Medical University, Harbin, China.
Xian
X
Jiang
Authors' Affiliations: The Hepatosplenic Surgery Center, Department of General Surgery, the First Affiliated Hospital of Harbin Medical University; and Departments of Gastroenterology and General Surgery, the Fourth Affiliated Hospital of Harbin Medical University, Harbin, China.
Jun
J
Xu
Authors' Affiliations: The Hepatosplenic Surgery Center, Department of General Surgery, the First Affiliated Hospital of Harbin Medical University; and Departments of Gastroenterology and General Surgery, the Fourth Affiliated Hospital of Harbin Medical University, Harbin, China.
Dali
D
Zhao
Authors' Affiliations: The Hepatosplenic Surgery Center, Department of General Surgery, the First Affiliated Hospital of Harbin Medical University; and Departments of Gastroenterology and General Surgery, the Fourth Affiliated Hospital of Harbin Medical University, Harbin, China.
Bing
B
Liu
Authors' Affiliations: The Hepatosplenic Surgery Center, Department of General Surgery, the First Affiliated Hospital of Harbin Medical University; and Departments of Gastroenterology and General Surgery, the Fourth Affiliated Hospital of Harbin Medical University, Harbin, China.
Shangha
S
Pan
Authors' Affiliations: The Hepatosplenic Surgery Center, Department of General Surgery, the First Affiliated Hospital of Harbin Medical University; and Departments of Gastroenterology and General Surgery, the Fourth Affiliated Hospital of Harbin Medical University, Harbin, China.
Xuesong
X
Dong
Authors' Affiliations: The Hepatosplenic Surgery Center, Department of General Surgery, the First Affiliated Hospital of Harbin Medical University; and Departments of Gastroenterology and General Surgery, the Fourth Affiliated Hospital of Harbin Medical University, Harbin, China.
Gang
G
Tan
Authors' Affiliations: The Hepatosplenic Surgery Center, Department of General Surgery, the First Affiliated Hospital of Harbin Medical University; and Departments of Gastroenterology and General Surgery, the Fourth Affiliated Hospital of Harbin Medical University, Harbin, China.
Zheng
Z
Wei
Authors' Affiliations: The Hepatosplenic Surgery Center, Department of General Surgery, the First Affiliated Hospital of Harbin Medical University; and Departments of Gastroenterology and General Surgery, the Fourth Affiliated Hospital of Harbin Medical University, Harbin, China.
Haiquan
H
Qiao
Authors' Affiliations: The Hepatosplenic Surgery Center, Department of General Surgery, the First Affiliated Hospital of Harbin Medical University; and Departments of Gastroenterology and General Surgery, the Fourth Affiliated Hospital of Harbin Medical University, Harbin, China.
Hongchi
H
Jiang
Authors' Affiliations: The Hepatosplenic Surgery Center, Department of General Surgery, the First Affiliated Hospital of Harbin Medical University; and Departments of Gastroenterology and General Surgery, the Fourth Affiliated Hospital of Harbin Medical University, Harbin, China kevsun88@hotmail.com.
Xueying
X
Sun
D001343:Autophagy / Q000235:genetics*; D006528:Carcinoma, Hepatocellular / Q000188:drug therapy / Q000235:genetics* / Q000473:pathology; D049109:Cell Proliferation / Q000187:drug effects; D019008:Drug Resistance, Neoplasm / Q000235:genetics; D056945:Hep G2 Cells; D006801:Humans; D008113:Liver Neoplasms / Q000188:drug therapy / Q000235:genetics* / Q000473:pathology; D058990:Molecular Targeted Therapy; D009536:Niacinamide / Q000008:administration & dosage / Q000031:analogs & derivatives; D051058:Oncogene Protein v-akt / Q000037:antagonists & inhibitors / Q000235:genetics*; D010671:Phenylurea Compounds / Q000008:administration & dosage; D034741:RNA, Small Interfering; D000077157:Sorafenib
D010671:Phenylurea Compounds; D034741:RNA, Small Interfering; D009536:Niacinamide; D000077157:Sorafenib; D051058:Oncogene Protein v-akt