title: Fibroid explants reveal a higher sensitivity against MDM2-inhibitor nutlin-3 than matching myometrium.
abstract: BACKGROUND
  Spontaneous cessation of growth is a frequent finding in uterine fibroids. Increasing evidence suggests an important role of cellular senescence in this growth control. Deciphering the underlying mechanisms of growth control that can be expected not only to shed light on the biology of the tumors but also to identify novel therapeutic targets.
  
  
  METHODS
  We have analyzed uterine leiomyomas and matching normal tissue for the expression of p14Arf and used explants to see if reducing the MDM2 activity using the small-molecule inhibitor nutlin-3 can induce p53 and activate genes involved in senescence and/or apoptosis. For these studies quantitative real-time RT-PCR, Western blots, and immunohistochemistry were used. Statistical analyses were performed using the student's t test.
  
  
  RESULTS
  An in depth analysis of 52 fibroids along with matching myometrium from 31 patients revealed in almost all cases a higher expression of p14Arf in the tumors than in the matching normal tissue. In tissue explants, treatment with the MDM2 inhibitor nutlin-3 induced apoptosis as well as senescence as revealed by a dose-dependent increase of the expression of BAX as well as of p21, respectively. Simultaneously, the expression of the proliferation marker Ki-67 drastically decreased. Western-blot analysis identified an increase of the p53 level as the most likely reason for the increased activity of its downstream markers BAX and p21. Because as a rule fibroids express much higher levels of p14Arf, a major negative regulator of MDM2, than matching myometrium it was then analyzed if fibroids are more sensitive against nutlin-3 treatment than matching myometrium. We were able to show that in most fibroids analyzed a higher sensibility than that of matching myometrium was noted with a corresponding increase of the p53 immunopositivity of the fibroid samples compared to those from myometrium.
  
  
  CONCLUSIONS
  The results show that uterine fibroids represent a cell population of advanced cellular age compared to matching myometrium. Moreover, the data point to members of the p53-network as to potential novel therapeutic targets for the treatment of uterine fibroids.
authors.affiliation: Center of Human Genetics, University of Bremen, Leobener Strasse ZHG, D-28359 Bremen, Germany.
authors.forename: Dominique N
authors.initials: DN
authors.lastname: Markowski
authors.forename: Burkhard M
authors.initials: BM
authors.lastname: Helmke
authors.forename: Arlo
authors.initials: A
authors.lastname: Radtke
authors.forename: Jennifer
authors.initials: J
authors.lastname: Froeb
authors.forename: Gazanfer
authors.initials: G
authors.lastname: Belge
authors.forename: Sabine
authors.initials: S
authors.lastname: Bartnitzke
authors.forename: Werner
authors.initials: W
authors.lastname: Wosniok
authors.forename: Iris
authors.initials: I
authors.lastname: Czybulka-Jachertz
authors.forename: Ulrich
authors.initials: U
authors.lastname: Deichert
authors.forename: Jörn
authors.initials: J
authors.lastname: Bullerdiek
mesh_terms: D000328:Adult; D000368:Aged; D017209:Apoptosis / Q000187:drug effects / Q000235:genetics; D016922:Cellular Senescence / Q000187:drug effects*; D005260:Female; D006801:Humans; D007093:Imidazoles / Q000494:pharmacology*; D007889:Leiomyoma / Q000235:genetics / Q000378:metabolism*; D008875:Middle Aged; D009215:Myometrium / Q000378:metabolism; D010879:Piperazines / Q000494:pharmacology*; D051736:Proto-Oncogene Proteins c-mdm2 / Q000037:antagonists & inhibitors* / Q000235:genetics; D025803:Tumor Suppressor Protein p14ARF / Q000187:drug effects / Q000378:metabolism; D016159:Tumor Suppressor Protein p53 / Q000187:drug effects / Q000378:metabolism; D014594:Uterine Neoplasms / Q000378:metabolism*
chemical_list: D007093:Imidazoles; D010879:Piperazines; D025803:Tumor Suppressor Protein p14ARF; D016159:Tumor Suppressor Protein p53; C482205:nutlin 3; C497206:MDM2 protein, human; D051736:Proto-Oncogene Proteins c-mdm2