Development of colonic neoplasms and expressions of p53 and p21 proteins in experimental colitis of mice induced by dextran sulfate sodium.
The mechanisms underlying the frequent development of colorectal carcinomas in patients with ulcerative colitis (UC) are still not understood. This study was conducted to investigate whether p53 and p21 protein expressions contribute to carcinogenesis in an experimental model with dextran sulfate sodium (DSS) treatment, and to establish if this colitis model is suitable for study of cancer development in UC. A total of 40 mice were subjected to four administration cycles of 4% DSS for 7 days followed by plain water for the subsequent 14 days. The 33-surviving mice were sacrificed to examine the malignant transformation of colonic mucosa morphologically and to determine p53 and p21 expressions immunohistochemically. After DSS treatment periods, there were marked irregularities in the mucosal layer, the thickness of the entire bowel wall and the shortness of the colon. Histologically, tumors were found in 13 out of 33 (39.4%) mice. These 13 cases included 9 with a solitary lesion and 4 with double tumors. There were occurrences of invasive carcinomas in 8 lesions, high-grade dysplasia in 3 lesions and low-grade-dysplasia in 6 lesions. One presented with a polypoid tumor, 5 mm in diameter, while 16 had small flat lesions. There were 13 tumors on the left-sided colon, as opposed to 4 on the right-sided colon. Histological differentiation of invading carcinomas revealed that 6 out of 8 lesions were comprised of well differentiated adenocarcinomas, while 2 were moderately differentiated adenocarcinomas. Overexpression of p53 protein was found in 4 out of 8 invasive carcinomas, 2 out of 3 high-grade dysplasia cases and 2 out of 6 low-grade dysplasia cases, whereas only 1 out of 8 with invasive carcinoma was positive for p21. This experimental colitis model suggests that p53 and p21 protein expressions may contribute to carcinogenesis in DSS-induced colitis in mice and appears suitable to study cancer development in UC.
Takesue
F
F
Dept. of General Surgery, Fukuoka Dental College Hospital, Japan.
Korenaga
D
D
Yao
T
T
Kabashima
A
A
Sugimachi
K
K
D000818:Animals; D003092:Colitis / Q000139:chemically induced / Q000150:complications* / Q000235:genetics; D003110:Colonic Neoplasms / Q000139:chemically induced* / Q000209:etiology / Q000235:genetics* / Q000473:pathology; D050759:Cyclin-Dependent Kinase Inhibitor p21; D016213:Cyclins / Q000235:genetics*; D016264:Dextran Sulfate / Q000633:toxicity*; D004195:Disease Models, Animal; D005260:Female; D005786:Gene Expression Regulation; D016158:Genes, p53; D007413:Intestinal Mucosa / Q000187:drug effects / Q000473:pathology*; D051379:Mice; D009361:Neoplasm Invasiveness; D016159:Tumor Suppressor Protein p53 / Q000235:genetics*
C493957:Cdkn1a protein, mouse; D050759:Cyclin-Dependent Kinase Inhibitor p21; D016213:Cyclins; D016159:Tumor Suppressor Protein p53; D016264:Dextran Sulfate