title: Hyperthermic treatment of DMBA-induced rat mammary cancer using magnetic nanoparticles.
abstract: BACKGROUND
  We have developed magnetite cationic liposomes (MCLs) and applied them as a mediator of local hyperthermia. MCLs can generate heat under an alternating magnetic field (AMF). In this study, the in vivo effect of hyperthermia mediated by MCLs was examined using 7,12-dimethylbenz(a)anthracene (DMBA)-induced rat mammary cancer as a spontaneous cancer model.
  
  
  METHODS
  MCLs were injected into the mammary cancer and then subjected to an AMF.
  
  
  RESULTS
  Four rats in 20 developed mammary tumors at more than 1 site in the body. The first-developed tumor in each of these 4 rats was selected and heated to over 43 degrees C following administration of MCLs by an infusion pump. After a series of 3 hyperthermia treatments, treated tumors in 3 of the 4 rats were well controlled over a 30-day observation period. One of the 4 rats exhibited regrowth after 2 weeks. In this rat, there were 3 sites of tumor regrowth. Two of these regrowths were reduced in volume and regressed completely after 31 days, although the remaining one grew rapidly. These results indicated hyperthermia-induced immunological antitumor activity mediated by the MCLs.
  
  
  CONCLUSIONS
  Our results suggest that hyperthermic treatment using MCLs is effective in a spontaneous cancer model.
authors.affiliation: 1Nanotherapy Co, Ltd, 19-11, Kikui 2-chome, Nishi-ku, Nagoya 451-0044, Japan. jun.motoyama@nipponkayaku.co.jp
authors.forename: Jun
authors.initials: J
authors.lastname: Motoyama
authors.forename: Noriyuki
authors.initials: N
authors.lastname: Yamashita
authors.forename: Tomio
authors.initials: T
authors.lastname: Morino
authors.forename: Masashi
authors.initials: M
authors.lastname: Tanaka
authors.forename: Takeshi
authors.initials: T
authors.lastname: Kobayashi
authors.forename: Hiroyuki
authors.initials: H
authors.lastname: Honda