Kawano R, Nishisaka T, Takeshima Y, Yonehara S, Inai K
Second Department of Pathology, Hiroshima University School of Medicine.
Jpn J Cancer Res. 1995 Sep;86(9):802-10. doi: 10.1111/j.1349-7006.1995.tb03089.x.
In order to elucidate the role of point mutation of the K-ras gene in the tumorigenetic process of lung tumors, an experimental model of lung lesions in mice induced by the administration of urethane was used. A total of 135 B6C3F1 male mice, 6 weeks old, were given urethane in the drinking water at 0, 6, 60, 600 or 1200 ppm, and were then killed after varying periods of time. The lung lesions were histologically characterized as hyperplasia, adenoma and adenocarcinoma. Point mutations in codons 12 and 61 of the K-ras gene were detected by polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) and confirmed by using dideoxy sequencing analysis. K-ras gene mutation was identified in 9 (23.7%) of 38 lesions classified as hyperplasia, 31 (46.3%) of 67 adenomas, and 3 (50%) of 6 adenocarcinomas. The most frequent mutation was an AT-to-TA transversion at the second base of codon 61 and this pattern accounted for 65% of the three mutant forms observed. These results suggest that the point mutation of K-ras gene is involved in all stages of mouse lung tumorigenesis, i.e., activation of this gene can also influence the later stages of lung lesions.
为了阐明K-ras基因点突变在肺肿瘤发生过程中的作用，采用了给小鼠饮用氨基甲酸乙酯诱导肺部病变的实验模型。总共135只6周龄的B6C3F1雄性小鼠，饮用含0、6、60、600或1200 ppm氨基甲酸乙酯的水，然后在不同时间段后处死。肺部病变在组织学上表现为增生、腺瘤和腺癌。通过聚合酶链反应-限制性片段长度多态性（PCR-RFLP）检测K-ras基因第12和61密码子的点突变，并通过双脱氧测序分析进行确认。在38例增生性病变中有9例（23.7%）、67例腺瘤中有31例（46.3%）以及6例腺癌中有3例（50%）检测到K-ras基因突变。最常见的突变是第61密码子第二个碱基处的AT到TA颠换，这种模式占观察到的三种突变形式的65%。这些结果表明，K-ras基因的点突变参与了小鼠肺肿瘤发生的所有阶段，即该基因的激活也可影响肺部病变的后期阶段。
