title: Cabozantinib reverses multidrug resistance of human hepatoma HepG2/adr cells by modulating the function of P-glycoprotein.
abstract: OBJECTIVE
  Cabozantinib, a small-molecule multitargeted tyrosine kinase inhibitor, has entered into a phase III clinical trial for the treatment of hepatocellular carcinoma (HCC). This study assessed the mechanistic effect of cabozantinib on the reversal of P-glycoprotein (P-gp)-mediated multidrug resistance (MDR).
  
  
  METHODS
  CCK-8 assays and tumour xenografts were used to investigate the reversal of MDR in vitro and in vivo respectively. Substrate retention assays were evaluated by fluorescence microscope and flow cytometry. Western blotting was used to detect protein expression levels. mRNA expression was determined by qPCR. The ATPase activity of P-gp was investigated using Pgp-Glo(™) assay systems. The binding mechanism of cabozantinib to P-gp at the molecular level was evaluated using docking analysis.
  
  
  RESULTS
  Cabozantinib enhanced the cytotoxicity of P-gp substrate drugs in HepG2/adr and HEK293-MDR1 cells but had no effect on non-P-gp substrates. In addition, cabozantinib increased the accumulation of P-gp substrates in HepG2/adr cells but had no effect in HepG2 cells. Furthermore, cabozantinib did not alter the expression of P-gp mRNA or protein but did stimulate the activity of P-gp ATPase. The docking study indicated that cabozantinib and verapamil may partially share a binding site on P-gp. The reversal concentrations of cabozantinib did not affect the expression of MET, AKT and ERK1/2. Significantly, cabozantinib increased the inhibitory efficacy of doxorubicin in P-gp-overexpressing HepG2/adr cell xenografts in nude mice.
  
  
  CONCLUSIONS
  Cabozantinib reverses P-gp-mediated MDR by directly inhibiting the efflux function of P-gp, indicating that cabozantinib may help to reverse P-gp-mediated MDR in HCC and other cancer chemotherapy.
authors.affiliation: Department of Hepatopancreatobiliary Surgery, Sun Yat-sen Memorial Hospital, Sun Yat-sen University, Guangzhou, China.
authors.forename: Qing-feng
authors.initials: QF
authors.lastname: Xiang
authors.forename: Dong-mei
authors.initials: DM
authors.lastname: Zhang
authors.forename: Jing-nan
authors.initials: JN
authors.lastname: Wang
authors.forename: Hong-wu
authors.initials: HW
authors.lastname: Zhang
authors.forename: Zhe-yu
authors.initials: ZY
authors.lastname: Zheng
authors.forename: Da-cheng
authors.initials: DC
authors.lastname: Yu
authors.forename: Ying-jie
authors.initials: YJ
authors.lastname: Li
authors.forename: Jun
authors.initials: J
authors.lastname: Xu
authors.forename: Ya-jin
authors.initials: YJ
authors.lastname: Chen
authors.forename: Chang-zhen
authors.initials: CZ
authors.lastname: Shang
mesh_terms: D020168:ATP Binding Cassette Transporter, Subfamily B, Member 1 / Q000187:drug effects* / Q000378:metabolism; D000813:Anilides / Q000494:pharmacology / Q000627:therapeutic use*; D000818:Animals; D006528:Carcinoma, Hepatocellular / Q000188:drug therapy*; D018432:Drug Resistance, Multiple / Q000187:drug effects*; D019008:Drug Resistance, Neoplasm / Q000187:drug effects*; D048049:Extracellular Signal-Regulated MAP Kinases / Q000378:metabolism; D005260:Female; D057809:HEK293 Cells; D056945:Hep G2 Cells; D006801:Humans; D008113:Liver Neoplasms / Q000188:drug therapy*; D008807:Mice, Inbred BALB C; D008819:Mice, Nude; D062105:Molecular Docking Simulation; D051057:Proto-Oncogene Proteins c-akt / Q000378:metabolism; D019859:Proto-Oncogene Proteins c-met / Q000378:metabolism; D011725:Pyridines / Q000494:pharmacology / Q000627:therapeutic use*; D011897:Random Allocation; D023041:Xenograft Model Antitumor Assays
chemical_list: D020168:ATP Binding Cassette Transporter, Subfamily B, Member 1; D000813:Anilides; D011725:Pyridines; C558660:cabozantinib; C491743:MET protein, human; D019859:Proto-Oncogene Proteins c-met; D051057:Proto-Oncogene Proteins c-akt; D048049:Extracellular Signal-Regulated MAP Kinases
keywords: P-glycoprotein; cabozantinib; chemotherapy; hepatocellular carcinoma; multidrug resistance