Detection-evaluation systems for carcinogens with the use of gene-defective mice

使用基因缺陷小鼠的致癌物检测评估系统

• 批准号: 09358015
• 负责人: SEKIGUCHI Mutsuo
• 金额: $ 15.49万
• 依托单位: Fukuoka Dental College
• 依托单位国家: 日本
• 项目类别: Grant-in-Aid for Scientific Research (A)
• 财政年份: 1997
• 资助国家: 日本
• 起止时间: 1997 至 1999
• 项目状态: 已结题
• 来源: https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-09358015/
• 关键词: Carcinogen; DNA repair enzyme; mismatch repair; gene-defective mice; alkylating agents; cell death; cancer; mutation; DNA修復系; 発がん物質; 検出・評価システム; DNA修復; アポトーシス; 酸素マジカル; 発がん; 修復欠損; 遺伝子ターゲティング; 致死効果

Mice with mutation in both alleles of the Mgmt and the Mlh1 gene, the former encoding a DNA repair methyltransferase and the latter a protein functioning at an early step of mismatch repair, are as resistant to the killing action of alkylating agents as are wild-type mice. These mice yielded a large number of tumors, when exposed to alkylating carcinogens, but this characteristic was subdued since they also showed a relatively high level of spontaneous tumorigenistiy, as the consequence of the defect in mismatch repair. This complexity is now resolved by introducing the Mlh1+/- mutation, instead of Mlh1-/-, in these methyltransferase-deficient mice. MlmtィイD1-/-ィエD1 Mlh1ィイD1+/-ィエD1 mice with about half the amount of MLH1 protein as MgmtィイD1-/-ィエD1 Mlh1ィイD1+/+ィエD1 mice, were resistant to the killing action of N-methyl-N-nitrosourea (MNU), up to the level of 30 mg/kg of body weight. Eight weeks after exposure to this dose of MNU, 40% of MNU-treated MgmtィイD1-/-ィエD1 Mlh1ィイD1+/-ィエD1 mice had thymic lymphoma and there was no tumor in these mice not given the treatment. It seems that the cellular content of MLH1 protein is a critical factor for determining if damaged cells enter into either one of the two pathways, leading to mutation induction and to apototic cell death. Loss of Mlh1 expression was frequently observed with tumors of MgmtィイD1-/-ィエD1 Mlh1ィイD1+/-ィエD1 mice, and this might be related to progression of the tumors.

在Mgmt和Mlh 1基因的两个等位基因中具有突变的小鼠，前者编码DNA修复甲基转移酶，后者是在错配修复的早期步骤起作用的蛋白质，与野生型小鼠一样对烷化剂的杀伤作用具有抗性。这些小鼠在暴露于烷基化致癌物时产生了大量肿瘤，但这种特征被抑制，因为它们也显示出相对高水平的自发性肿瘤发生，这是错配修复缺陷的结果。这种复杂性现在通过在这些甲基转移酶缺陷小鼠中引入Mlh 1 +/-突变而不是Mlh 1-/-来解决。MLH 1蛋白质含量约为Mgmt亚硝基D1-/-亚硝基D1 Mlh 1亚硝基D1+/+亚硝基D1小鼠一半的Mlmt亚硝基D1-/-亚硝基D1 Mlh 1亚硝基D1+/-亚硝基D1小鼠对N-甲基-N-亚硝基脲（MNU）的杀伤作用具有抗性，高达30 mg/kg体重。在暴露于该剂量的MNU后8周，40%的MNU治疗的Mgmt α D1-/-β D1 Mlh 1 α D1+/-β D1小鼠患有胸腺淋巴瘤，并且在未给予治疗的这些小鼠中没有肿瘤。MLH 1蛋白的细胞含量似乎是决定受损细胞是否进入两条途径之一，导致突变诱导和凋亡细胞死亡的关键因素。Mlh 1表达的缺失经常在Mgmt α D1-/-β D1 Mlh 1 α D1+/-β D1小鼠的肿瘤中观察到，这可能与肿瘤的进展有关。

项目成果

Kawate, H. et al.: "A defect in a single allele of the Mlh1 gene causes dissociation of killing and tumorigenic actions of an alkylating carcinogen in methyltransferase-deficient mice."

Kawate, H. 等人：“Mlh1 基因的单个等位基因的缺陷会导致甲基转移酶缺陷小鼠中烷化致癌物的杀伤和致瘤作用解离。”

K.Sakumi et al.: "Methylnitrosourea-induced tumorigenesis in MGMT gene knockout mice" Cancer Res.57. 2415-2418 (1997)

K.Sakumi 等人：“MGMT 基因敲除小鼠中甲基亚硝基脲诱导的肿瘤发生”Cancer Res.57。

M.Sekiguchi et al.: "Roles of DNA repair methyltransferase in mutagenesis and carcinogenesis" Jpn.J.Human Genet.42. 389-399 (1997)

M.Sekiguchi 等人：“DNA 修复甲基转移酶在诱变和癌变中的作用”Jpn.J.Human Genet.42。

Tominaga, Y. et al.: "Alkylation-induced apoptosis of embryonic stem cells in which the gene for DNA-repair, methyltransferase, had been disrupted by gene targeting."Carcinogenesis. 18. 889-896 (1997)

Tominaga, Y. 等人：“烷基化诱导胚胎干细胞凋亡，其中 DNA 修复基因甲基转移酶已被基因靶向破坏。”致癌作用。

H.Igarashi et al.: "Organization and expression of the mouse MTH1 gene for preventing transversion mutation" J.Biol.Chem.272. 3766-3772 (1997)

H.Igarashi 等人：“用于预防颠换突变的小鼠 MTH1 基因的组织和表达”J.Biol.Chem.272。