Baumann H, Eldredge D
Cancer Res. 1982 Jun;42(6):2398-406.
Rat hepatoma tissue culture cells have retained only a few liver-specific membrane functions. To find out whether transformation of these cells led to the appearance of tumor-specific membrane glycoprotein structures, which might also be present in released form in the circulation of tumor-bearing animals, we compared immunologically the sera and ascites fluids of normal and of hepatoma-bearing rats. For structural identification, we used polyspecific antibodies against the membrane glycoproteins of the hepatoma cells. Crossed immunoelectrophoresis of the body fluids resulted in the separation of several antigens, one of which appears to be tumor specific. Immunoelectrophoretic analyses of the glycoproteins from the membranes of liver and hepatoma cells revealed many shared antigens; in one instance, we could assign the membrane associated form to major antigen detected in the serum. Characterization of the molecular size and charge of the two selected antigens by two-dimensional gel electrophoresis indicated that the hepatoma cells products were not completely sialylated. In the case of the circulating, hepatoma-specific antigen, this property appears to result in hepatic clearance of the more basic ("asialo") portion of the glycoprotein species via the receptor-mediated uptake of galactose-terminated glycoproteins. The result was the accumulation of the acidic forms of the antigen in the serum and ascites fluid of tumor-bearing rats.
大鼠肝癌组织培养细胞仅保留了少数肝脏特异性膜功能。为了弄清楚这些细胞的转化是否导致肿瘤特异性膜糖蛋白结构的出现，而这种结构可能也以释放形式存在于荷瘤动物的循环系统中，我们对正常大鼠和荷瘤大鼠的血清及腹水进行了免疫学比较。为了进行结构鉴定，我们使用了针对肝癌细胞膜糖蛋白的多特异性抗体。体液的交叉免疫电泳分离出了几种抗原，其中一种似乎是肿瘤特异性的。对肝脏和肝癌细胞膜糖蛋白的免疫电泳分析显示出许多共同抗原；在一个实例中，我们能够将膜相关形式与血清中检测到的主要抗原联系起来。通过二维凝胶电泳对两种选定抗原的分子大小和电荷进行表征表明，肝癌细胞产物并未完全唾液酸化。就循环中的肝癌特异性抗原而言，这种特性似乎导致糖蛋白物种中更碱性（“去唾液酸”）部分通过半乳糖末端糖蛋白的受体介导摄取而被肝脏清除。结果是荷瘤大鼠血清和腹水中抗原的酸性形式积累。
