Growth inhibition of tumor cells by transfection with β-1,4-glanctosyltransferase gene II or V.

在细胞恶性转化过程中，N-乙酰氨基葡萄糖基转移酶V的激活诱导了N-连接低聚糖的高度分枝，而β-1，4-GalT活性在这一生物事件中没有明显的变化。当检测β-1，4-GalT家族成员在癌变细胞和正常对照细胞中的基因表达水平时，β-1，4-GalT II的基因表达水平降低，而β-1，4-GalT V的基因表达水平上升，而其他β-1，4-GalT的基因表达水平无明显变化。将人β-1，4-GalT II正义基因或β-1，4-GalT V反义基因导入B16-F10小鼠黑色素瘤细胞，皮下移植到C57B/L6小鼠体内，可抑制肿瘤的形成。为了研究它们是如何诱导肿瘤抑制的，将细胞培养在纤维连接蛋白(FN)包被的平板上，无血清。模拟转染组B16-F10细胞呈圆形，而两种基因转染组细胞均呈排列排列的肌动蛋白细丝铺展。用Rca-I与以β-1，4-半乳糖封端的寡糖和L-PHA与高支链低聚糖结合的凝集素印迹分析表明，β-1，4-GalT基因转染后，这些凝集素对这些凝集素的反应性发生了变化。这些结果表明，包括纤维连接蛋白受体在内的膜糖蛋白的半乳糖化改变影响了细胞与纤维连接蛋白底物的粘附性，从而抑制了肿瘤的形成。

Upon malignant transformation of cells, highly branching of N-linked oligosaccharides is induced by activation of N-acetylglucosaminyltransferase V. However, no significant change in β-1, 4-GalT activities was found during this biological event. When gene expression levels of the β-1, 4-GalT family members were examined between malignantly transformed cells and their normal counterparts, those of β-1, 4-GalT II decreased while those of β-1, 4-GalT V increased without significant changes in those of other β-1, 4-GalTs. When B16-F10 mouse melanoma cells were transfected with human β-1, 4-GalT II sense CDNA or β-1, 4-GalT V anti-sense cDNA, and transplanted subcutaneously in C57B/L6 mouse, tumor formation was suppressed in the gene-transfected cells. In order to investigate how tumor suppression was induced by them, the cells were cultured on fibronectin (FN)-coated plates without serum. The mock-transfected B16-F10 cells stayed in a round shape while both gene-transfected cells showed cell spreading aligned with actin filament as revealed with phalloidin staining. Lectin blot analysis of membrane glycoproteins from the tumors and cultured cells using RCA-I which interacts with oligosaccharides terminated with β-1, 4-linked galactose and L-PHA which binds to highly branched oligosaccharides showed that reactivities to these lectins are changed upon transfection of the β-1, 4-GalT genes. These results indicate that the altered galactosylation induced to the membrane glycoproteins including fibronectin receptor affects adhesiveness of the cells to fibronectin substrate, thus leading to the suppression of the tumor formation.