β‐Catenin mutations in a mouse model of inflammation‐related colon carcinogenesis induced by 1,2‐dimethylhydrazine and dextran sodium sulfate

Abstract

In a previous study, we developed a novel mouse model for colitisrelated carcinogenesis, utilizing a single dose of azoxymethane (AOM) followed by dextran sodium sulfate (DSS) in drinking water. In the present study, we investigated whether colonic neoplasms can be developed in mice initiated with a single injection of another genotoxic colonic carcinogen 1,2-dimethylhydrazine (DMH), instead of AOM and followed by exposure of DSS in drinking water. Male crj: CD-1 (ICR) mice were given a single intraperitoneal administration (10, 20 or 40 mg/kg body weight) of DMH and 1-week oral exposure (2% in drinking water) of a non-genotoxic carcinogen, DSS. All animals were killed at week 20, histological alterations and immunohistochemical expression of β β β β-catenin, cyclooxygenase (COX-2) and inducible nitric oxide synthase (iNOS) were examined in induced colonic epithelial lesions (colonic dysplasias and neoplasms). Also, the β β β β-catenin gene mutations in paraffin-embedded colonic adenocarcinomas were analyzed by the single strand conformation polymorphism method, restriction enzyme fragment length polymorphism and direct sequencing. The incidences of colonic neoplasms with dysplastic lesions developed were 100% with 2.29 ± ± ± ± 0.95 multiplicity, and 100% with 10.38 ± ± ± ± 4.00 multiplicity in mice given DMH at doses of 10 mg/kg or 20 mg/kg and 2%DSS, respectively. Although approximately half of the mice given DMH at a dose of 40 mg/kg bodyweight were dead after 2-3 days after the injection, mice who received DMH 40 mg/kg and 2%DSS had 100% incidence of colonic neoplasms with 9.75 ± ± ± ± 6.29 multiplicity. Immunohistochemical investigation revealed that adnocarcinomas, induced by DMH at all doses and 2%DSS, showed positive reactivities against β β β β-catenin, COX-2 and iNOS. In DMH/ DSS-induced adenocarcinomas, 10 of 11 (90.9%) adenocacrcinomas had β β β β-catenin gene mutations. Half of the mutations were detected at codon 37 or 41, encoding serine and threonine that are direct targets for phosphorylation by glycogen synthase kinase-3β β β β. The present results suggests that, as in the previously reported model (AOM/DSS) our experimental protocol, DMH initiation followed by DSS, may provide a novel and useful mouse model for investigating inflammation-related colon carcinogenesis and for identifying xenobiotics with modifying effects. (Cancer Sci 2005; 96: 69-76) C olorectal cancer (CRC) is one of the most common nonsmoking related cancers. The risk for CRC is associated with extent and duration of inflammatory bowel disease (IBD), including ulcerative colitis (UC) and Crohn's disease.(1,2) The etiopathogenesis of IBD remains uncertain, although it is generally assumed that chronic inflammation is the primary driving force.(3) To understand the pathogenesis of IBD and IBD-related CRC, several animal models were reported. The chemically induced and genetic models of colonic inflammation do not completely mimic the disease situation found in UC patients, (4) although they are more readily available, reproduci...

Parthenolide induces apoptosis in colitis-associated colon cancer, inhibiting NF-κB signaling

“…AOM is a procarcinogen that upon metabolic activation, causes the formation of O 6 -methylguanine (23). AOM induces the development of tumors in the distal colon of rodents and is commonly used to elicit CRC in experimental animals (24)(25)(26). Thus, the present study used a CAC model in which six-week-old mice were injected with a single dose of AOM followed by DSS administered in the drinking water to analyze the antitumor activities of PT.…”

Prevention of colitis‐associated carcinogenesis in a mouse model by diet supplementation with ursodeoxycholic acid

“…The DSS-induced intermittent inflammation leads to a slow development of carcinomas within 8 months. 12 This time can be reduced to 5 months if colitis-associated colon carcinogenesis is accelerated by a single injection of the carcinogens AOM 13 or dimethylhydrazine (DMH), 14 both of which are known to activate the wnt pathway. 14,15 The objective of the present work was to test the effects of UDCA on carcinogenesis induced solely by colitis and to compare them with the concentration of bile acids in the colonic fecal water.…”

“…12 This time can be reduced to 5 months if colitis-associated colon carcinogenesis is accelerated by a single injection of the carcinogens AOM 13 or dimethylhydrazine (DMH), 14 both of which are known to activate the wnt pathway. 14,15 The objective of the present work was to test the effects of UDCA on carcinogenesis induced solely by colitis and to compare them with the concentration of bile acids in the colonic fecal water. For this purpose, the mice with colitis were given either UDCA at a dose previously shown to inhibit chemical carcinogenesis 6 or-as a control-CA, which is metabolised to DCA and was previously shown to enhance chemical carcinogenesis.…”

Chemopreventive effects of caraway powder and oils to suppress 1, 2- dimethylhydrazine-induced colon carcinogenesis

“…In regards to the effect of DMH metabolite produced by CYP450 on beta-catenin gene expression [15,16,18,19], the data of this research together with our previous results [34,35] imply that feeding of rats with caraway essential oils and powder could modulate the enzymes interfere with DMH metabolism (GST and CYP1A1) leading to the decreased level of β-catenin gene expression. These entire events, finally leaded to the decreased level of ACF formation terminating in decreased progression of colon…”

“…In the progression of DMH carcinogenesis, the reactive metabolite causes the methylation of DNA in colonic epithelial cell leaded to β-catenin gene mutation [14][15][16][17][18][19]. β-catenin is a cadherin-binding protein that also functions as a transcriptional activator when complexes in the nucleus with members of the TCF/LEF family [20].…”