PP60C-SRC ACTIVATION IN HUMAN-COLON CARCINOMA
PP60C-SRC ACTIVATION IN HUMAN-COLON CARCINOMA
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DOI：
10.1172/jci114113
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发表时间：
1989-06-01
影响因子：
15.9
通讯作者：
ECKHART, W
中科院分区：
文献类型：
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作者：
CARTWRIGHT, CA;KAMPS, MP;ECKHART, W
我们测定了人结肠癌细胞系和肿瘤中pp 60 c-src的体外蛋白酪氨酸激酶活性。来自9个癌细胞系中的6个的pp 60 c-src的活性比来自正常结肠粘膜细胞或人或啮齿动物成纤维细胞的pp 60 c-src的活性高（平均而言，通过烯醇化酶磷酸化测量的5倍，或通过自磷酸化测量的8倍）。同样，21例原发性结肠癌中有13例的pp 60 c-src活性比肿瘤旁正常结肠粘膜的pp 60 c-src活性高5 - 7倍。pp 60 c-src活性的增加并不仅仅是由于pp 60 c-src蛋白水平的增加，这表明pp 60 c-src激酶的比活性在肿瘤细胞中升高。来自结肠癌细胞和正常结肠粘膜细胞的pp 60 c-src在相似的位点被磷酸化。我们用磷酸酪氨酸抗体免疫印迹法来鉴定结肠细胞中蛋白酪氨酸激酶的底物。在大多数结肠癌细胞系中检测到三种含磷酸酪氨酸的蛋白质的水平显著高于正常结肠粘膜细胞或人或大鼠成纤维细胞。所有具有升高的pp 60 c-src体外激酶活性的结肠癌细胞系在体内均显示酪氨酸上的蛋白磷酸化增加，表明存在活化的蛋白酪氨酸激酶。
We measured the in vitro protein-tyrosine kinase activity of pp60c-src from human colon carcinoma cell lines and tumors. The activity of pp60c-src from six of nine carcinoma cell lines was higher (on average, fivefold as measured by enolase phosphorylation, or eightfold as measured by autophosphorylation) than that of pp60c-src from normal colonic mucosal cells, or human or rodent fibroblasts. Similarly, the activity of pp60c-src from 13 of 21 primary colon carcinomas was five- or sevenfold higher than that of pp60c-src from normal colonic mucosa adjacent to the tumor. The increased pp60c-src activity did not result solely from an increase in the level of pp60c-src protein, suggesting the specific activity of the pp60c-src kinase is elevated in the tumor cell. pp60c-src from colon carcinoma cells and normal colonic mucosal cells was phosphorylated at similar sites. We used immunoblotting with antibodies to phosphotyrosine to identify substrates of protein-tyrosine kinases in colonic cells. Three phosphotyrosine-containing proteins were detected at significantly higher levels in most colon carcinoma cell lines than in normal colonic mucosal cells or human or rat fibroblasts. All colon carcinoma cell lines with elevated pp60c-src in vitro kinase activity, showed increased phosphorylation of proteins on tyrosine in vivo, suggesting the presence of an activated protein-tyrosine kinase(s).