β-Catenin mutations in a mouse model of inflammation-related colon carcinogenesis induced by 1,2-dimethylhydrazine and dextran sodium sulfate
β-Catenin mutations in a mouse model of inflammation-related colon carcinogenesis induced by 1,2-dimethylhydrazine and dextran sodium sulfate
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DOI：
10.1111/j.1349-7006.2005.00020.x
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发表时间：
2005-02-01
期刊：
影响因子：
5.7
通讯作者：
Tanaka, T
中科院分区：
文献类型：
--
作者：
Kohno, H;Suzuki, R;Tanaka, T
在之前的一项研究中，我们开发了一种新的结肠炎相关致癌小鼠模型，使用单剂量氧化偶氮甲烷（AOM），然后在饮用水中加入葡聚糖硫酸钠（DSS）。在本研究中，我们研究了单次注射另一种遗传毒性结肠致癌物 1,2-二甲基肼 (DMH)（代替 AOM）并随后在饮用水中暴露 DSS 的小鼠是否会出现结肠肿瘤。雄性crj：CD-1（ICR）小鼠腹腔内注射DMH（10、20或40mg/kg体重），并口服非遗传毒性致癌物DSS（2%的饮用水）1周。所有动物在第20周处死，在诱导的结肠上皮病变（结肠发育不良和肿瘤）中检查β-连环蛋白、环氧合酶（COX-2）和诱导型一氧化氮合酶（iNOS）的组织学改变和免疫组织化学表达。并采用单链构象多态性、限制性内切酶片段长度多态性和直接测序的方法对石蜡包埋结肠腺癌中的β-catenin基因突变进行分析。在给予10mg/kg或20mg/kg剂量的DMH和2%DSS的小鼠中，出现发育异常病变的结肠肿瘤的发生率为100%（多重性为2.29+/-0.95）和100%（多重性为10.38+/-4.00）。虽然以 40 mg/kg 体重剂量给予 DMH 的小鼠在注射 23 天后大约有一半死亡，但接受 40 mg/kg DMH 和 2% DSS 的小鼠结肠肿瘤发生率为 100%，多重性为 9.75 +/- 6.29。免疫组织化学研究表明，所有剂量的 DMH 和 2% DSS 诱导的腺癌均表现出针对 β-连环蛋白、COX-2 和 iNOS 的阳性反应性。在 DMH/DSS 诱导的腺癌中，11 个腺癌中有 10 个 (90.9%) 存在 β-连环蛋白基因突变。一半的突变是在密码子 37 或 41 处检测到的，编码丝氨酸和苏氨酸，它们是糖原合酶激酶 3 beta 磷酸化的直接目标。目前的结果表明，正如之前报道的模型（AOM/DSS）一样，我们的实验方案（DMH 启动后进行 DSS）可能提供一种新颖且有用的小鼠模型，用于研究炎症相关的结肠癌发生和识别具有修饰作用的外源性物质。
In a previous study, we developed a novel mouse model for colitis-related 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 beta-catenin, cyclooxygenase (COX-2) and inducible nitric oxide synthase (iNOS) were examined in induced colonic epithelial lesions (colonic dysplasias and neoplasms). Also, the beta-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 23 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 beta-catenin, COX-2 and iNOS. In DMH/DSS-induced adenocarcinomas, 10 of 11 (90.9%) adenocacrcinomas had beta-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-3 beta. 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.