title: Rapamycin enhances cetuximab cytotoxicity by inhibiting mTOR-mediated drug resistance in mesenchymal hepatoma cells.
abstract: The synergistic effect of combined drug therapy provides an enhanced treatment for advanced liver cancer. We aimed to investigate the underlying mechanism of cetuximab sensitization by rapamycin in hepatoma cells. Four hepatoma cell lines, HepG2, HuH7, SNU-387, and SNU-449, were treated with cetuximab or cetuximab plus rapamycin and growth inhibition was evaluated by measuring relative cell viability and cell proliferation. The cell phenotype was determined for each hepatoma cell line by western blot analysis of E-cadherin and vimentin expression and mTOR activation status. To identify the role of mTOR signaling in cetuximab sensitization, we used deferoxamine-mediated hypoxia to induce epithelial-mesenchymal transition (EMT) in HuH7 and HepG2 cells and measured mTOR activity after rapamycin treatment. Rapamycin significantly increased cetuximab cytotoxicity in hepatoma cell lines with differential sensitivities. Phenotypic differences among hepatoma cell lines, specifically epithelial (HuH7 and HepG2) and mesenchymal (SNU-387 and SNU-449), correlated with the efficacy of rapamycin cotreatment, although rapamycin treatment did not affect cell phenotype. We further showed that rapamycin inhibits mTOR in mesenchymal SNU-387 and SNU-449 cells. In addition, the induction of EMT in HuH7 and HepG2 cells significantly decreased cetuximab cytotoxicity; however, rapamycin treatment significantly restored cetuximab sensitivity and decreased mTOR signaling in these cells. In conclusion, we identified significant differences in rapamycin-induced cetuximab sensitization between epithelial and mesenchymal hepatoma cells. We therefore report that rapamycin cotreatment enhances cetuximab cytotoxicity by inhibiting mTOR signaling in mesenchymal cells.
authors.affiliation: Department of Hepatobiliary and Pancreatic Surgery; The Second Affiliated Hospital; Zhejiang University School of Medicine; Hangzhou, PR China.
authors.forename: Wei
authors.initials: W
authors.lastname: Chen
authors.affiliation: Department of Hepatobiliary and Pancreatic Surgery; The Second Affiliated Hospital; Zhejiang University School of Medicine; Hangzhou, PR China.
authors.forename: Qi-Da
authors.initials: QD
authors.lastname: Hu
authors.affiliation: Department of Hepatobiliary and Pancreatic Surgery; The Second Affiliated Hospital; Zhejiang University School of Medicine; Hangzhou, PR China.
authors.forename: Xue-Feng
authors.initials: XF
authors.lastname: Xia
authors.affiliation: Department of Hepatobiliary and Pancreatic Surgery; The Second Affiliated Hospital; Zhejiang University School of Medicine; Hangzhou, PR China.
authors.forename: Chao
authors.initials: C
authors.lastname: Liang
authors.affiliation: Department of Hepatobiliary and Pancreatic Surgery; The Second Affiliated Hospital; Zhejiang University School of Medicine; Hangzhou, PR China.
authors.forename: Hao
authors.initials: H
authors.lastname: Liu
authors.affiliation: Department of Hepatobiliary and Pancreatic Surgery; The Second Affiliated Hospital; Zhejiang University School of Medicine; Hangzhou, PR China.
authors.forename: Qi
authors.initials: Q
authors.lastname: Zhang
authors.affiliation: Department of Hepatobiliary and Pancreatic Surgery; The Second Affiliated Hospital; Zhejiang University School of Medicine; Hangzhou, PR China.
authors.forename: Tao
authors.initials: T
authors.lastname: Ma
authors.forename: Feng
authors.initials: F
authors.lastname: Liang
authors.affiliation: Department of Hepatobiliary and Pancreatic Surgery; The Second Affiliated Hospital; Zhejiang University School of Medicine; Hangzhou, PR China.
authors.forename: Ting-Bo
authors.initials: TB
authors.lastname: Liang
mesh_terms: D061067:Antibodies, Monoclonal, Humanized / Q000494:pharmacology*; D000970:Antineoplastic Agents / Q000494:pharmacology*; D015820:Cadherins / Q000378:metabolism; D006528:Carcinoma, Hepatocellular; D015687:Cell Hypoxia; D045744:Cell Line, Tumor; D049109:Cell Proliferation / Q000187:drug effects; D002470:Cell Survival / Q000187:drug effects; D000068818:Cetuximab; D019008:Drug Resistance, Neoplasm / Q000187:drug effects*; D004357:Drug Synergism; D058750:Epithelial-Mesenchymal Transition / Q000187:drug effects; D006801:Humans; D008113:Liver Neoplasms; D010641:Phenotype; D020123:Sirolimus / Q000494:pharmacology*; D058570:TOR Serine-Threonine Kinases / Q000378:metabolism*; D014746:Vimentin / Q000378:metabolism
chemical_list: D061067:Antibodies, Monoclonal, Humanized; D000970:Antineoplastic Agents; D015820:Cadherins; D014746:Vimentin; C546842:MTOR protein, human; D058570:TOR Serine-Threonine Kinases; D000068818:Cetuximab; D020123:Sirolimus
keywords: cetuximab; combined therapy; liver neoplasms; mTOR pathway; rapamycin