title: Glutamyl- but not aspartyl-aminopeptidase activity is modified in serum of N-methyl nitrosourea-induced rat mammary tumours.
abstract: BACKGROUND
  The rat model of breast cancer induced by the administration of N-methyl-nitrosourea (NMU) constitutes a useful tool for dissecting the initiation, promotion and progression process of carcinogenesis. Angiogenesis, the recruitment of new blood vessels, is an essential component of the metastatic pathway. Tumour vessels have an aberrant response to constrictor hormones, such as angiotensin II (Ang II). Ang II degradation to form angiotensin III (Ang III) begins with the action of glutamyl aminopeptidase (GluAP) and aspartyl aminopeptidase (AspAP), named together as aminopeptidase A activity (APA). The present work analyses GluAP and AspAP activities in serum of NMU-induced rat mammary tumours, to evaluate the putative value of these activities as biological markers of the initiation and promotion of the disease.
  
  
  METHODS
  Serum AspAP and GluAP activities were measured fluorimetrically using their corresponding aminoacyl-beta-naphthylamide.
  
  
  RESULTS
  The increase found in GluAP but not in AspAP suggests an increase in Ang III and a decrease in Ang II serum circulating levels.
  
  
  CONCLUSIONS
  The decrease in Ang III may be responsible for the overexpression of AT1 receptors described in breast cancer. However, increased levels of Ang III, which exhibit the same affinity for the AT1 receptor, would favour the development of the disease.
authors.affiliation: Departamento de Ciencias de la Salud, Area de Fisiología, Universidad de Jaén, Jaén, Spain.
authors.forename: María Pilar
authors.initials: MP
authors.lastname: Carrera
authors.forename: María Jesus
authors.initials: MJ
authors.lastname: Ramírez-Expósito
authors.forename: María Teresa
authors.initials: MT
authors.lastname: Valenzuela
authors.forename: María Jesus
authors.initials: MJ
authors.lastname: García
authors.forename: María Dolores
authors.initials: MD
authors.lastname: Mayas
authors.forename: José Manuel
authors.initials: JM
authors.lastname: Martínez-Martos
mesh_terms: D000818:Animals; D014408:Biomarkers, Tumor / Q000097:blood; D002273:Carcinogens / Q000494:pharmacology*; D002455:Cell Division / Q000502:physiology; D005260:Female; D043384:Glutamyl Aminopeptidase / Q000097:blood*; D008325:Mammary Neoplasms, Experimental / Q000139:chemically induced / Q000201:enzymology* / Q000473:pathology; D008770:Methylnitrosourea / Q000494:pharmacology*; D051381:Rats; D017208:Rats, Wistar
chemical_list: D014408:Biomarkers, Tumor; D002273:Carcinogens; D008770:Methylnitrosourea; D043384:Glutamyl Aminopeptidase