Mitsumori K, Wakana S, Yamamoto S, Kodama Y, Yasuhara K, Nomura T, Hayashi Y, Maronpot R R
Division of Pathology, National Institute of Health Sciences, Tokyo, Japan.
Mol Carcinog. 1997 Nov;20(3):298-307. doi: 10.1002/(sici)1098-2744(199711)20:3<298::aid-mc6>3.0.co;2-h.
To determine if hemizygous transgenic mice carrying the human c-Ha-ras gene (CB6F1-Tg Hras2 mice (Hras2 mice)) are susceptible to the carcinogenic potential of known murine carcinogens, male and female Hras2 mice and their non-transgenic CB6F1 littermates (non-Tg mice) were each given a single intraperitoneal injection of 60 mg of vinyl carbamate (VC)/kg body weight or saline (vehicle control) and monitored for 16 wk without further treatment. At necropsy, grossly visible tumors were fixed for histopathologic diagnosis and, when of sufficient size, portions were frozen for subsequent molecular analysis. Nine of 31 male and nine of 29 female Hras2 mice treated with VC died within 16 wk as a result of lung tumor burden. At the termination of the study, lung tumors (alveolar-bronchiolar epithelial neoplasms and hemangiosarcomas) and focal alveolar-bronchiolar hyperplasias were present in both sexes of Hras2 and non-Tg mice treated with VC; there were significantly more proliferative lung lesions in Hras2 than non-Tg mice. Splenic hemangiosarcomas and squamous cell tumors of the forestomach were induced in male and female VC-treated Hras2 mice but not in VC-treated non-Tg mice. Polymerase chain reaction-single-strand conformation polymorphism analysis and DNA sequencing of the induced lung tumors revealed point mutations at codon 61 of the transgene in two of 29 lung tumors (one of 16 in males and one of 13 in females) from VC-treated Hras2 mice; no mutations in murine Ki-ras were found in these tumors. Point mutations at codons 12 and 61 of the murine Ki-ras gene were observed, however, in one of 10 and six of 10 lung tumors respectively, from VC-treated non-Tg mice. These findings indicate that Hras2 mice are highly sensitive to pulmonary neoplasms and splenic and lung hemangiosarcomas after treatment with VC. The molecular analyses suggest that point mutations of the transgene and the murine Ki-ras gene do not play a major role in VC induction of pulmonary neoplasms in these transgenic mice.
为了确定携带人类c-Ha-ras基因的半合子转基因小鼠（CB6F1-Tg Hras2小鼠（Hras2小鼠））是否对已知的鼠类致癌物的致癌潜力敏感，分别给雄性和雌性Hras2小鼠及其非转基因CB6F1同窝仔鼠（非Tg小鼠）腹腔注射一次60 mg/kg体重的乙烯基氨基甲酸酯（VC）或生理盐水（溶剂对照），并在不进行进一步处理的情况下监测16周。尸检时，将肉眼可见的肿瘤固定用于组织病理学诊断，当肿瘤足够大时，取部分组织冷冻用于后续分子分析。31只接受VC处理的雄性Hras2小鼠中有9只，29只接受VC处理的雌性Hras2小鼠中有9只因肺肿瘤负荷在16周内死亡。在研究结束时，接受VC处理的Hras2和非Tg小鼠的两性均出现了肺肿瘤（肺泡-支气管上皮肿瘤和血管肉瘤）和局灶性肺泡-支气管增生；Hras2小鼠的增殖性肺病变明显多于非Tg小鼠。雄性和雌性接受VC处理的Hras2小鼠诱导出脾血管肉瘤和前胃鳞状细胞瘤，但接受VC处理的非Tg小鼠未出现。对诱导的肺肿瘤进行聚合酶链反应-单链构象多态性分析和DNA测序发现，在接受VC处理的Hras2小鼠的29个肺肿瘤中有2个（雄性16个中的1个，雌性13个中的1个）转基因第61密码子发生点突变；在这些肿瘤中未发现鼠类Ki-ras基因发生突变。然而，在接受VC处理的非Tg小鼠的10个肺肿瘤中，分别有1个和6个在鼠类Ki-ras基因的第12和61密码子处观察到点突变。这些发现表明，Hras2小鼠在用VC处理后对肺肿瘤以及脾和肺血管肉瘤高度敏感。分子分析表明，转基因和鼠类Ki-ras基因的点突变在这些转基因小鼠中VC诱导肺肿瘤过程中不起主要作用。
