Gmeiner B M, Wolf G
Cancer Biochem Biophys. 1985 Dec;8(2):103-18.
After demonstrating that three bladder cancer cell lines (human bladder transitional cell carcinoma, MGH-U1; rat bladder transitional cell carcinoma, RBTCC; Nara rat bladder epidermal carcinoma, NBT-II) had galactosyltransferase (GT) activity in their cell surfaces, we investigated the effect of increasing cell density on the activity of this enzyme. All three cell lines responded to increased cell density by increased activity of cell-surface GT towards endogenous acceptor. By the use of exogenous acceptor, we showed that in the two transitional cell carcinoma lines (human and rat), the increased activity was probably caused by increased levels of endogenous acceptor rather than enzyme. In the rat bladder epidermal carcinoma line, on the other hand, increased GT activity seemed to be the result of increased levels of the enzyme. These conclusions were supported by the increased shedding of GT into the medium with increasing cell density in case of the epidermal carcinoma cells, but not the two transitional cell carcinoma lines. Total cell-associated GT activity would indicate that, in contrast to the two transitional cell carcinoma lines, the bladder epidermal carcinoma cells may have an increased rate of synthesis of GT as confluence is approached.
在证实三种膀胱癌细胞系（人膀胱移行细胞癌，MGH-U1；大鼠膀胱移行细胞癌，RBTCC；奈良大鼠膀胱表皮癌，NBT-II）在其细胞表面具有半乳糖基转移酶（GT）活性后，我们研究了细胞密度增加对该酶活性的影响。所有三种细胞系均通过细胞表面GT对内源性受体活性的增加来响应细胞密度的增加。通过使用外源性受体，我们表明在两种移行细胞癌系（人和大鼠）中，活性增加可能是由于内源性受体水平的增加而非酶的增加所致。另一方面，在大鼠膀胱表皮癌系中，GT活性的增加似乎是酶水平增加的结果。在表皮癌细胞中，随着细胞密度增加，GT向培养基中的释放增加，而在两种移行细胞癌系中则不然，这些结果支持了上述结论。总的细胞相关GT活性表明，与两种移行细胞癌系不同，随着汇合度的接近，膀胱表皮癌细胞可能具有更高的GT合成速率。
