title: Aglepristone decreases proliferation in progesterone receptor-positive canine mammary carcinomas.
abstract: BACKGROUND
  Progesterone receptor (PR) antagonist aglepristone (RU534) has been used successfully for pregnancy termination and therapy of pyometra, vaginal tumors, and mammary hyperplasia in bitches and queens. All of these conditions share with canine mammary carcinomas the expression of PR.
  
  
  OBJECTIVE
  To study the effect of RU534 on proliferation and apoptosis in canine mammary carcinomas in relation to PR expression.
  
  
  METHODS
  Twenty-seven nonspayed bitches with mammary carcinomas were treated with either 2 doses of 20 mg/kg RU534 (n = 22, RU534-treated group) or oil placebo (n = 5, control group) on days 1 and 8.
  
  
  METHODS
  Tumor samples were collected before (day 1) and after (day 15) treatment for immunohistochemistry. PR expression, proliferation index (PI), and apoptotic index (AI) were determined using antibodies against PR, Ki67, and cleaved lamin A/C antigens, respectively. The effect of treatment on these parameters was analyzed.
  
  
  RESULTS
  Differential expression of PR between day 1 (59.1% PR-positive tumors) and day 15 (36.4% PR-positive tumors) was observed in RU534-treated tumors exclusively. After RU534 treatment, mean PI was significantly decreased in PR-positive but unchanged in PR-negative RU534-treated tumors. A reduction of ≥20% in PI was found in 61.5% of RU534-treated tumors with PR expression. Conversely, no effect on AI was observed after RU534 treatment.
  
  
  CONCLUSIONS
  Neoadjuvant RU534 treatment had PR expression-related inhibiting effects on proliferation of canine mammary carcinoma cells.
authors.affiliation: Department of Comparative Pathology, Veterinary Faculty, University of Córdoba, Córdoba, Spain.
authors.forename: S
authors.initials: S
authors.lastname: Guil-Luna
authors.forename: R
authors.initials: R
authors.lastname: Sánchez-Céspedes
authors.forename: Y
authors.initials: Y
authors.lastname: Millán
authors.forename: F J
authors.initials: FJ
authors.lastname: De Andrés
authors.forename: E
authors.initials: E
authors.lastname: Rollón
authors.forename: V
authors.initials: V
authors.lastname: Domingo
authors.forename: F
authors.initials: F
authors.lastname: Guscetti
authors.forename: J
authors.initials: J
authors.lastname: Martín de Las Mulas
mesh_terms: D000818:Animals; D000970:Antineoplastic Agents / Q000627:therapeutic use*; D002277:Carcinoma / Q000188:drug therapy / Q000662:veterinary*; D004283:Dog Diseases / Q000188:drug therapy*; D004285:Dogs; D004963:Estrenes / Q000627:therapeutic use*; D005260:Female; D015972:Gene Expression Regulation, Neoplastic / Q000187:drug effects; D015674:Mammary Neoplasms, Animal / Q000188:drug therapy*; D011980:Receptors, Progesterone / Q000235:genetics / Q000378:metabolism*
chemical_list: D000970:Antineoplastic Agents; D004963:Estrenes; D011980:Receptors, Progesterone; C419063:aglepristone