title: A rat model of pancreatic ductal adenocarcinoma: targeting chemical carcinogens.
abstract: BACKGROUND
  Current experimental models of pancreatic cancer either fail to reproduce the ductal phenotype or cause simultaneous cancers in other organs also. To develop an animal of pancreatic cancer that accurately mimics the human condition, we restricted carcinogenic exposure to the pancreas and specifically targeted ductal epithelial cells. Three different carcinogens were either implanted directly into the pancreas or infused into the pancreatic duct, with or without near-total pancreatectomy (as a means of inducing pancreatic ductal cell proliferation).
  
  
  METHODS
  Groups of male Sprague-Dawley rats were exposed to varying doses of dimethylbenzanthracine (DMBA), methynitronitrosoguanidine, or ethylnitronitrosoguanidine either through direct implantation into the pancreas or infusion into the pancreatic duct. Near-total pancreatectomy was added in all groups except two DMBA implantation groups. Surviving rats were killed at 3, 6, 9, or 12 months, and the pancreata were evaluated histologically.
  
  
  RESULTS
  All three carcinogens caused pancreatic inflammation, ductal hyperplasia, atypia, and dysplasia beginning by 3 months and becoming more prominent at later time points. Only DMBA caused frequent invasive pancreatic ductal adenocarcinoma, which was first evident by 6 months. The prevalence of pancreatic cancer among DMBA-treated rats evaluated after 10 months was 39% (19 of 49). The addition of pancreatic resection did not enhance pancreatic cancer development.
  
  
  CONCLUSIONS
  Of the strategies tested, only direct implantation of DMBA into the rat pancreas frequently produces pancreatic cancer histologically similar to human ductal adenocarcinoma. The development of hyperplastic, atypical, and dysplastic changes preceding and accompanying carcinomas suggests that these lesions are preneoplastic. This model recapitulates the progression from normal to neoplastic epithelium and is likely to be useful for the study of morphologic and molecular mechanisms underlying the early stages of pancreatic carcinogenesis and for the investigation of novel diagnostic and therapeutic techniques.
authors.affiliation: Department of Surgery, Massachusetts General Hospital, Harvard Medical School, Boston 02114, USA.
authors.forename: J A
authors.initials: JA
authors.lastname: Rivera
authors.forename: F
authors.initials: F
authors.lastname: Graeme-Cook
authors.forename: J
authors.initials: J
authors.lastname: Werner
authors.forename: K
authors.initials: K
authors.lastname: Z'graggen
authors.forename: A K
authors.initials: AK
authors.lastname: Rustgi
authors.forename: D W
authors.initials: DW
authors.lastname: Rattner
authors.forename: A L
authors.initials: AL
authors.lastname: Warshaw
authors.forename: C
authors.initials: C
authors.lastname: Fernández-del Castillo
mesh_terms: D015127:9,10-Dimethyl-1,2-benzanthracene / Q000009:adverse effects / Q000494:pharmacology; D000818:Animals; D002273:Carcinogens / Q000009:adverse effects / Q000494:pharmacology*; D018270:Carcinoma, Ductal, Breast / Q000139:chemically induced* / Q000473:pathology / Q000601:surgery; D004195:Disease Models, Animal; D005354:Fibrosarcoma / Q000139:chemically induced / Q000473:pathology / Q000601:surgery; D006965:Hyperplasia; D008297:Male; D008769:Methylnitronitrosoguanidine / Q000009:adverse effects / Q000031:analogs & derivatives / Q000494:pharmacology; D010180:Pancreatectomy; D010183:Pancreatic Ducts / Q000473:pathology / Q000601:surgery; D010190:Pancreatic Neoplasms / Q000139:chemically induced* / Q000473:pathology / Q000601:surgery; D051381:Rats; D017207:Rats, Sprague-Dawley; D012513:Sarcoma, Experimental / Q000139:chemically induced / Q000473:pathology / Q000601:surgery
chemical_list: D002273:Carcinogens; D008769:Methylnitronitrosoguanidine; C013525:ENNG; D015127:9,10-Dimethyl-1,2-benzanthracene