title: The thrombin inhibitor, argatroban, inhibits breast cancer metastasis to bone.
abstract: BACKGROUND
  Breast cancer has the potential to metastasize to bone, causing debilitating symptoms. Although many tumor cells have thrombin-generating systems originating from tissue factor (TF), therapy in terms of the coagulation system is not well established. To elucidate the efficacy of the thrombin inhibitor, argatroban, on bone metastasis, we investigated TF activation and vascular endothelial growth factor (VEGF) secretion on treatment with thrombin and argatroban.
  
  
  METHODS
  MDA-231 breast cancer cells were treated with thrombin in presence or absence of argatroban, and TF activity was measured in the form of activated factor X. Enzyme-linked immunosorbent assay (ELISA) was used to measure VEGF concentrations in the medium. MDA-231 cells were injected into the left heart ventricle of mice, and then argatroban or saline was administered intraperitoneally for 28 days. After 28 days, incidence of bone metastasis was evaluated in the limbs by radiography.
  
  
  RESULTS
  TF activity and VEGF secretion were upregulated by thrombin. Argatroban inhibited the enhancement of TF activity and VEGF secretion induced by thrombin. In vivo analysis revealed that the number of metastasized limbs in the argatroban group was significantly lower compared with the saline group (P < 0.05).
  
  
  CONCLUSIONS
  Thrombin not only enhances VEGF secretion but also has a positive feedback mechanism to reexpress TF. These results indicate that inhibition of thrombin is of great value in suppression of tumor metastasis. Argatroban is a noteworthy and useful thrombin inhibitor because it has already been used in the clinical setting and has antimetastatic effects in vivo.
authors.affiliation: Department of Orthopedic Surgery, Mie University School of Medicine, 2-174 Edobashi, Tsu, Mie, Japan. kasanum@gmail.com
authors.forename: Kunihiro
authors.initials: K
authors.lastname: Asanuma
authors.forename: Hiroki
authors.initials: H
authors.lastname: Wakabayashi
authors.forename: Takayuki
authors.initials: T
authors.lastname: Okamoto
authors.forename: Yumiko
authors.initials: Y
authors.lastname: Asanuma
authors.forename: Nobuyuki
authors.initials: N
authors.lastname: Akita
authors.forename: Tomoaki
authors.initials: T
authors.lastname: Yoshikawa
authors.forename: Tatsuya
authors.initials: T
authors.lastname: Hayashi
authors.forename: Akihiko
authors.initials: A
authors.lastname: Matsumine
authors.forename: Atsumasa
authors.initials: A
authors.lastname: Uchida
authors.forename: Akihiro
authors.initials: A
authors.lastname: Sudo
mesh_terms: D000818:Animals; D000991:Antithrombins / Q000494:pharmacology*; D001120:Arginine / Q000031:analogs & derivatives; D001835:Body Weight / Q000187:drug effects; D001859:Bone Neoplasms / Q000517:prevention & control* / Q000556:secondary; D001943:Breast Neoplasms / Q000473:pathology / Q000517:prevention & control*; D004797:Enzyme-Linked Immunosorbent Assay; D005260:Female; D006801:Humans; D051379:Mice; D010875:Pipecolic Acids / Q000494:pharmacology*; D013449:Sulfonamides; D013917:Thrombin / Q000037:antagonists & inhibitors*; D013925:Thromboplastin / Q000378:metabolism; D014407:Tumor Cells, Cultured; D042461:Vascular Endothelial Growth Factor A / Q000378:metabolism
chemical_list: D000991:Antithrombins; D010875:Pipecolic Acids; D013449:Sulfonamides; D042461:Vascular Endothelial Growth Factor A; C467480:vascular endothelial growth factor A, mouse; D013925:Thromboplastin; D001120:Arginine; D013917:Thrombin; C031942:argatroban