title: Mature acinar cells are refractory to carcinoma development by targeted activation of Ras oncogene in adult rats.
abstract: Pancreatic ductal adenocarcinoma (PDA) is one of the most debilitating malignancies in humans. A thorough understanding of the cytogenesis of this disease will aid in establishing successful treatments. We have developed an animal model which uses adult Hras(G12V) and Kras(G12V) transgenic rats in which oncogene expression is regulated by the Cre/loxP system and neoplastic lesions are induced by injection of adenovirus-expressing Cre recombinase. When adenovirus with Cre recombinase under the control of the CMV enhancer/chicken beta-actin (CAG) promoter (Ad-CAG-Cre) is injected into the pancreatic duct of these animals, pancreatic neoplasias develop. Pathologically, the origin of these lesions is duct, intercalated duct, and centroacinar cells, but not acinar cells. The present study was undertaken to test the effect of acinar cell-specific oncogenic ras expression. Adult transgenic rats were injected with adenovirus with Cre recombinase under the control of the acinar cell-specific promoters amylase (Ad-Amy-Cre) and elastase-1 (Ad-Ela-Cre) or under the control of the non-specific CAG promoter. Injection of either Ad-Amy-Cre or Ad-Ela-Cre into the pancreatic ducts of transgenic animals in which oncogenic Kras is tagged with hemagglutinin (HA), HA-Kras(G12V) rats resulted in expression of oncogenic ras in acinar cells but not in duct, intercalated duct, or centroacinar cells. Notably, injected animals did not develop any observable proliferative or neoplastic lesions. In marked contrast, injection of Ad-CAG-Cre resulted in pancreatic cancer development within 4 weeks. These results indicate that adult acinar cells are refractory to Ras oncogene activation and do not develop neoplasia in this model.
authors.affiliation: Department of Gastroenterology and Metabolism, Nagoya City University Graduate School of Medical Sciences, Nagoya, Japan.
authors.forename: Hajime
authors.initials: H
authors.lastname: Tanaka
authors.forename: Katsumi
authors.initials: K
authors.lastname: Fukamachi
authors.forename: Mitsuru
authors.initials: M
authors.lastname: Futakuchi
authors.forename: David B
authors.initials: DB
authors.lastname: Alexander
authors.forename: Ne
authors.initials: N
authors.lastname: Long
authors.forename: Shojiro
authors.initials: S
authors.lastname: Tamamushi
authors.forename: Kohtaro
authors.initials: K
authors.lastname: Minami
authors.forename: Susumu
authors.initials: S
authors.lastname: Seino
authors.forename: Hirotaka
authors.initials: H
authors.lastname: Ohara
authors.forename: Takashi
authors.initials: T
authors.lastname: Joh
authors.forename: Hiroyuki
authors.initials: H
authors.lastname: Tsuda
mesh_terms: D000818:Animals; D021441:Carcinoma, Pancreatic Ductal / Q000209:etiology* / Q000473:pathology; D005260:Female; D011905:Genes, ras; D019426:Integrases / Q000502:physiology; D008679:Metaplasia; D046790:Pancreas, Exocrine / Q000473:pathology*; D010190:Pancreatic Neoplasms / Q000209:etiology* / Q000473:pathology; D051381:Rats; D017207:Rats, Sprague-Dawley; D019076:Transgenes
chemical_list: C045073:Cre recombinase; D019426:Integrases