title: Methotrexate and 5-aminoimidazole-4-carboxamide riboside exert synergistic anticancer action against human breast cancer and hepatocellular carcinoma.
abstract: OBJECTIVE
  To investigate the influences of methotrexate (MTX) on the anticancer actions and pharmacokinetics of 5-aminoimidazole-4-carboxamide riboside (AICA riboside) in human breast cancer and hepatocellular carcinoma.
  
  
  METHODS
  Human breast cancer cell line MCF-7 and human hepatocellular carcinoma cell line HepG2 were examined. The cell proliferation was assessed using a sulforhodamine B assay. Western blotting and radioactivity assays were used to analyze the phosphorylation of AMPK. The DNA synthesis was analyzed with BrdU incorporation. Nude mice bearing MCF-7 cell xenografts were used to for in vivo study. MTX (50 mg/kg, ip, per week) and AICA riboside (200 mg/kg, ip, every other day) were administered the animals for 2 weeks. The concentrations of AICA riboside and its active metabolite AICA ribotide in the plasma and tumors were measured with HPLC.
  
  
  RESULTS
  Synergistic cytotoxicity in vitro was observed with MTX (0.1, 0.5, and 1 μmol/L) combined with AICA riboside (0.25-1 mmol/L) in MCF-7 cells, and with MTX (0.5 and 1 μmol/L) combined with AICA riboside (0.5 and 1 mmol/L) in HepG2 cells. MTX (1 μmol/L) significantly enhanced the AICA riboside-induced AMPK activation and BrdU incorporation in both MCF-7 and HepG2 cells. Co-treatment with MTX and AICA riboside exerted more potent inhibition on the tumor growth in nude mice than either drug alone. After injection of AICA riboside (200 mg/kg, iv) in nude mice bearing MCF-7 xenografts, MTX (50 mg/kg, iv) significantly increased the concentrations of AICA riboside and its active metabolite AICA ribotide in tumors.
  
  
  CONCLUSIONS
  MTX and AICA riboside exert synergistic anticancer action against MCF-7 and HepG2 cells in vitro and in vivo. MTX increases the concentration of AICA riboside and its active metabolite AICA ribotide in tumors in vivo.
authors.affiliation: State Key Laboratory of Natural and Biomimetic Drugs, Peking University Health Science Center, Beijing, China.
authors.forename: Xiao-liang
authors.initials: XL
authors.lastname: Cheng
authors.forename: Tian-yan
authors.initials: TY
authors.lastname: Zhou
authors.forename: Bo
authors.initials: B
authors.lastname: Li
authors.forename: Meng-yao
authors.initials: MY
authors.lastname: Li
authors.forename: Liang
authors.initials: L
authors.lastname: Li
authors.forename: Zai-quan
authors.initials: ZQ
authors.lastname: Li
authors.forename: Wei
authors.initials: W
authors.lastname: Lu
mesh_terms: D000620:Aminoimidazole Carboxamide / Q000008:administration & dosage*; D000818:Animals; D017209:Apoptosis / Q000187:drug effects / Q000502:physiology; D001943:Breast Neoplasms / Q000188:drug therapy* / Q000473:pathology; D006528:Carcinoma, Hepatocellular / Q000188:drug therapy* / Q000473:pathology; D049109:Cell Proliferation / Q000187:drug effects; D004357:Drug Synergism; D005260:Female; D056945:Hep G2 Cells; D006801:Humans; D008114:Liver Neoplasms, Experimental / Q000188:drug therapy* / Q000473:pathology; D061986:MCF-7 Cells; D008727:Methotrexate / Q000008:administration & dosage*; D051379:Mice; D008807:Mice, Inbred BALB C; D008819:Mice, Nude; D023041:Xenograft Model Antitumor Assays / Q000379:methods
chemical_list: D000620:Aminoimidazole Carboxamide; D008727:Methotrexate