title: Immunohistochemical characterization of N-methyl-N-nitrosourea-induced mammary tumours of Sprague-Dawley rats.
abstract: BACKGROUND
  Single dose of N-methyl-N-nitrosourea (MNU) was shown to induce malignant tumours in susceptible rat strains. However, such tumours are not well-characterized.
  
  
  METHODS
  We characterized MNU-induced tumours in Sprague-Dawley rats using ultrasonographic, radiographic and immunohistochemical (IHC) methods.
  
  
  RESULTS
  In 27 rats, 41 tumours developed, appearing ultrasonographically as hypodense, non-homogenic areas with signal enhancement at their periphery. Out of these, 39 were of malignant epithelial origin, with an IHC phenotype closely-resembling that of human invasive ductal breast carcinoma. One case was diagnosed as carcinosarcoma. IHC analysis revealed that Ki-67 antigen expression correlated positively with tumour volume (r=0.40, p=0.0079). Moreover, tumours with α-smooth muscle actin in the tumour stroma were characterized by a higher proliferative rate as compared to those without its expression (p<0.05).
  
  
  CONCLUSIONS
  This rat model of chemical carcinogenesis may be suitable for examining breast cancer development and progression.
authors.affiliation: Department of Physiotherapy, Wroclaw University School of Physical Education, Paderewskiego 35, 51-612 Wroclaw, Poland. marek.wozniewski@awf.wroc.pl.
authors.forename: Bartosz
authors.initials: B
authors.lastname: Pula
authors.forename: Iwona
authors.initials: I
authors.lastname: Malicka
authors.forename: Katarzyna
authors.initials: K
authors.lastname: Pawlowska
authors.forename: Urszula
authors.initials: U
authors.lastname: Paslawska
authors.forename: Marek
authors.initials: M
authors.lastname: Cegielski
authors.forename: Marzena
authors.initials: M
authors.lastname: Podhorska-Okolow
authors.forename: Piotr
authors.initials: P
authors.lastname: Dziegiel
authors.forename: Marek
authors.initials: M
authors.lastname: Wozniewski
mesh_terms: D000818:Animals; D018270:Carcinoma, Ductal, Breast / Q000139:chemically induced / Q000378:metabolism* / Q000473:pathology; D002296:Carcinosarcoma / Q000139:chemically induced / Q000378:metabolism* / Q000473:pathology; D064200:Cdh1 Proteins / Q000378:metabolism; D005260:Female; D006801:Humans; D007150:Immunohistochemistry; D007633:Keratins / Q000378:metabolism; D008325:Mammary Neoplasms, Experimental / Q000139:chemically induced / Q000378:metabolism* / Q000473:pathology; D008770:Methylnitrosourea; D016612:Paraffin Embedding; D051381:Rats; D017207:Rats, Sprague-Dawley; D011980:Receptors, Progesterone / Q000378:metabolism; D047368:Tumor Burden
chemical_list: D064200:Cdh1 Proteins; D011980:Receptors, Progesterone; D007633:Keratins; D008770:Methylnitrosourea
keywords: Breast cancer; MNU; immunohistochemistry; rat carcinoma; rodent models