Staley C A, Parikh N U, Gallick G E
Department of Tumor Biology, The University of Texas M.D. Anderson Cancer Center, Houston 77030, USA.
Cell Growth Differ. 1997 Mar;8(3):269-74.
In greater than 80% of colon tumors and established cell lines, the specific activities of the protein tyrosine kinases pp60(c-src) and pp62(c-yes) are increased with respect to normal colonic epithelial cells. However, no mutations in either gene have been identified in colon tumors. Therefore, the possible biological consequences of activations of these protein tyrosine kinases in colon tumors have been unclear. To determine if pp60(c-src) activation affects growth and tumorigenicity of established colon tumor cell lines, an antisense expression vector that specifically reduces pp60(c-src) expression was constructed. The vector was transfected into HT 29 cells, an established colon tumor cell line in which both pp60(c-src) and pp62(c-yes) are activated. Two stable subclones were isolated in which pp60(c-src) but not pp62(c-yes) expression and activity were reduced. These established cell lines proliferated more slowly than parental cells proportionately to reduction in pp60(c-src) expression. When injected into nude mice, antisense transfected cells formed slow-growing tumors; however, the rate of tumor growth was reduced far greater than would be predicted from decreased proliferation rates in tissue culture. In contrast, stable subclones transfected with a comparable "sense" expression vector were unaltered in growth rates in tissue culture and in nude mice with respect to parental HT 29 cells. These data demonstrate that the activation of pp60(c-src) alone contributes to the tumorigenicity of HT 29 cells, a cell line widely used as a model for biological properties of colon carcinoma. Furthermore, because pp60(c-src) and pp62(c-yes) appear redundant to the growth regulation of normal colonic epithelial cells, the data suggest that src-specific inhibitors might be of therapeutic value for colon cancer.
在超过80%的结肠肿瘤及已建立的细胞系中，蛋白酪氨酸激酶pp60（c-src）和pp62（c-yes）的比活性相对于正常结肠上皮细胞有所增加。然而，在结肠肿瘤中尚未发现这两个基因有任何突变。因此，这些蛋白酪氨酸激酶在结肠肿瘤中的激活可能产生的生物学后果尚不清楚。为了确定pp60（c-src）的激活是否影响已建立的结肠肿瘤细胞系的生长和致瘤性，构建了一种能特异性降低pp60（c-src）表达的反义表达载体。该载体被转染到HT 29细胞中，HT 29是一种已建立的结肠肿瘤细胞系，其中pp60（c-src）和pp62（c-yes）均被激活。分离出两个稳定的亚克隆，其中pp60（c-src）的表达和活性降低，但pp62（c-yes）未受影响。这些已建立的细胞系增殖速度比亲代细胞慢，与pp60（c-src）表达的降低成比例。当注射到裸鼠体内时，反义转染细胞形成生长缓慢的肿瘤；然而，肿瘤生长速度的降低幅度远大于根据组织培养中增殖率降低所预测的幅度。相比之下，用类似的“正义”表达载体转染的稳定亚克隆在组织培养和裸鼠中的生长速度相对于亲代HT 29细胞没有改变。这些数据表明，单独激活pp60（c-src）会导致HT 29细胞的致瘤性，HT 29细胞系被广泛用作结肠癌生物学特性的模型。此外，由于pp60（c-src）和pp62（c-yes）在正常结肠上皮细胞的生长调节中似乎具有冗余性，这些数据表明src特异性抑制剂可能对结肠癌具有治疗价值。
