Fujita K, Ohuchi N, Yao T, Okumura M, Fukushima Y, Kanakura Y, Kitamura Y, Fujita J
Department of Internal Medicine, School of Medicine, Fukuoka University, Japan.
Gastroenterology. 1987 Dec;93(6):1339-45. doi: 10.1016/0016-5085(87)90264-2.
To define the extent of involvement of ras oncogenes in human gastric cancers, we surveyed for the presence of ras oncogenes, activated by either point mutations within their coding sequences or overexpression of ras protein p21, by the combined use of several analytic techniques. Primary gastric cancers were first analyzed by deoxyribonucleic acid transfection assay using NIH/3T3 cells as recipients and by restriction enzyme analysis, which detects point mutations at codon 12 of the H-ras gene. None of seven tumors analyzed scored as positive. Furthermore, none of them had ras p21 with altered electrophoretic mobility on immunoprecipitation and Western blotting, confirming the absence of ras oncogenes activated by point mutations in these tumors. However, in 6 of 7 tumors, the amounts of p21 exceeded that in human placenta. Amplification of the K-ras gene was found in 1 of 11 (including the 7 described above) gastric cancers. Immunohistochemical analysis of ras p21 expression in these 11 tumors was then carried out using the anti-ras p21 monoclonal antibody RAP-5. All cancers showed more reactivity with RAP-5 than did normal mucosa adjacent to the cancers, indicating increased expression of ras p21. These results indicated that transformation of the stomach mucosa from the normal to the malignant phenotype is rarely associated with activation of ras genes by point mutations, but is frequently associated with enhanced expression of ras p21.
为了确定ras癌基因在人类胃癌中的参与程度，我们联合使用了几种分析技术，以检测ras癌基因的存在情况，这些癌基因可通过其编码序列内的点突变或ras蛋白p21的过表达而被激活。首先，利用NIH/3T3细胞作为受体进行脱氧核糖核酸转染分析，并通过限制性内切酶分析（检测H-ras基因第12密码子处的点突变）对原发性胃癌进行分析。所分析的7个肿瘤均未评分为阳性。此外，它们中没有一个在免疫沉淀和蛋白质印迹法检测时ras p21的电泳迁移率发生改变，这证实了这些肿瘤中不存在由点突变激活的ras癌基因。然而，在7个肿瘤中的6个中，p21的量超过了人胎盘组织中的量。在11个（包括上述7个）胃癌中有1个发现了K-ras基因的扩增。然后使用抗ras p21单克隆抗体RAP-5对这11个肿瘤中ras p21的表达进行免疫组织化学分析。所有癌症与RAP-5的反应性均高于癌旁正常黏膜，表明ras p21表达增加。这些结果表明，胃黏膜从正常表型向恶性表型的转变很少与ras基因通过点突变激活有关，但经常与ras p21的表达增强有关。
