title: Midkine inhibitors: application of a simple assay procedure to screening of inhibitory compounds.
abstract: BACKGROUND
  Midkine is a heparin-binding cytokine and is involved in etiology of various diseases. Thus, midkine inhibitors are expected to be helpful in treatment of many diseases.
  
  
  METHODS
  We developed a simple assay for midkine activity based on midkine-dependent migration of osteblastic cells. Midkine inhibitors were searched as materials that inhibit this midkine activity. To develop peptides that inhibit midkine activity, we constructed models in which C-terminal half of midkine interacted with alpha4beta1-integrin. Low molecular weight compounds which are expected to bind to midkine with high affinity were searched by in silico screening with the aid of Presto-X2 program.
  
  
  RESULTS
  Among peptides in putative binding sites of midkine and the integrin, a peptide derived from beta1-integrin and that derived from the first beta sheet of the C-terminal half of midkine significantly inhibited midkine activity. Two low molecular weight compounds found by in silico screening exhibited no toxicity to target cells, but inhibited midkine activity. They are trifluoro compounds: one (PubChem 4603792) is 2-(2,6-dimethylpiperidin-1-yl)-4-thiophen-2-yl-6-(trifluoromethy)pyrimidine, and the other has a related structure.
  
  
  CONCLUSIONS
  The assay procedure is helpful in screening midkine inhibitors. All reagents described here might become mother material to develop clinically effective midkine inhibitors.
authors.affiliation: Department of Health Science, Faculty of Psychological and Physical Science, Aichi Gakuin University, 12 Araike, Iwasaki-cho, Nisshin, Aichi 470-0195, Japan. tmurama@dpc.agu.ac.jp.
authors.forename: Takashi
authors.initials: T
authors.lastname: Matsui
authors.forename: Keiko
authors.initials: K
authors.lastname: Ichihara-Tanaka
authors.forename: Chen
authors.initials: C
authors.lastname: Lan
authors.forename: Hisako
authors.initials: H
authors.lastname: Muramatsu
authors.forename: Toshiharu
authors.initials: T
authors.lastname: Kondou
authors.forename: Chizuru
authors.initials: C
authors.lastname: Hirose
authors.forename: Sadatoshi
authors.initials: S
authors.lastname: Sakuma
authors.forename: Takashi
authors.initials: T
authors.lastname: Muramatsu