title: Macrophages as potential targets for zoledronic acid outside the skeleton-evidence from in vitro and in vivo models.
abstract: OBJECTIVE
  Multiple cell types of the tumour microenvironment, including macrophages, contribute to the response to cancer therapy. The anti-resorptive agent zoledronic acid (ZOL) has anti-tumour effects in vitro and in vivo, but it is not known to what extent macrophages are affected by this agent. We have therefore investigated the effects of ZOL on macrophages using a combination of in vitro and in vivo models.
  
  
  METHODS
  J774 macrophages were treated with ZOL in vitro, alone and in combination with doxorubicin (DOX), and the levels of apoptosis and necrosis determined. Uptake of zoledronic acid was assessed by detection of unprenylated Rap1a in J774 macrophages in vitro, in peritoneal macrophages and in macrophage populations isolated from subcutaneously implanted breast cancer xenografts following ZOL treatment in vivo.
  
  
  RESULTS
  Exposure of J774 macrophages to 5 μM ZOL for 24 h caused a significant increase in the levels of uRap1A, and higher doses/longer exposure induced apoptotic cell death. DOX (10 nM/24 h) and ZOL (10 μM/4 h) given in sequence induced significantly increased levels of apoptotic cell death compared to single agents. Peritoneal macrophages and macrophage populations isolated from breast tumour xenografts had detectable levels of uRap1A 24 h following a single, clinically achievable dose of 100 μg/kg ZOL in vivo.
  
  
  CONCLUSIONS
  We demonstrate that macrophages are sensitive to sequential administration of DOX and ZOL, and that both peritoneal and breast tumour associated macrophages rapidly take up ZOL in vivo. Our data support that macrophages may contribute to the anti-tumour effect of ZOL.
authors.affiliation: Department of Oncology, CR-UK/YCR Sheffield Cancer Research Centre, University of Sheffield, Sheffield, UK.
authors.forename: T L
authors.initials: TL
authors.lastname: Rogers
authors.forename: N
authors.initials: N
authors.lastname: Wind
authors.forename: R
authors.initials: R
authors.lastname: Hughes
authors.forename: F
authors.initials: F
authors.lastname: Nutter
authors.forename: H K
authors.initials: HK
authors.lastname: Brown
authors.forename: I
authors.initials: I
authors.lastname: Vasiliadou
authors.forename: P D
authors.initials: PD
authors.lastname: Ottewell
authors.forename: I
authors.initials: I
authors.lastname: Holen
mesh_terms: D000818:Animals; D000971:Antineoplastic Combined Chemotherapy Protocols / Q000627:therapeutic use*; D017209:Apoptosis / Q000187:drug effects; D015153:Blotting, Western; D001943:Breast Neoplasms / Q000188:drug therapy* / Q000378:metabolism / Q000473:pathology; D002460:Cell Line; D045744:Cell Line, Tumor; D049109:Cell Proliferation / Q000187:drug effects; D004164:Diphosphonates / Q000008:administration & dosage / Q000494:pharmacology*; D004305:Dose-Response Relationship, Drug; D004317:Doxorubicin / Q000008:administration & dosage / Q000494:pharmacology; D004357:Drug Synergism; D005260:Female; D006801:Humans; D007093:Imidazoles / Q000008:administration & dosage / Q000494:pharmacology*; D008264:Macrophages / Q000187:drug effects* / Q000378:metabolism; D017737:Macrophages, Peritoneal / Q000187:drug effects / Q000378:metabolism; D051379:Mice; D008807:Mice, Inbred BALB C; D008819:Mice, Nude; D017368:Protein Prenylation / Q000187:drug effects; D059016:Tumor Microenvironment / Q000187:drug effects*; D023041:Xenograft Model Antitumor Assays; D000077211:Zoledronic Acid; D020827:rap1 GTP-Binding Proteins / Q000378:metabolism
chemical_list: D004164:Diphosphonates; D007093:Imidazoles; D000077211:Zoledronic Acid; D004317:Doxorubicin; D020827:rap1 GTP-Binding Proteins