Byrd J C, Dahiya R, Huang J, Kim Y S
GI Research Lab, VA Medical Center, San Francisco, California 94121, USA.
Eur J Cancer. 1995;31A(9):1498-505. doi: 10.1016/0959-8049(95)00248-h.
Previous studies from our laboratory have shown that benzyl-alpha-GalNAc inhibits the glycosylation of mucin in colon cancer cells. In this study, we determined whether benzyl-alpha-GalNAc inhibits mucin glycosylation in KATO III gastric cancer cells. We also examined its effects on expression of mucin antigens, and compared the mucins made by KATO III with those of a colonic cancer cell line, Caco-2. Results of these experiments suggest that benzyl-alpha-GalNAc (2 mM) inhibited [3H]glucosamine labelling of mucins by 82% in KATO III and by 70% in Caco-2. For both cell lines, the mucin secreted in the presence of benzyl-alpha-GalNAc was less acidic. Both cell lines secreted benzyl-oligosaccharides, but those from KATO III (8-9 sugars) were larger than those from Caco-2 (6-7 sugars). In mucins purified from the medium of treated cells, peripheral carbohydrate antigens (sialyl Lex in KATO III and terminal fucose in Caco-2) were decreased (compared with control), while core carbohydrate antigens (T antigen in both cell lines and sialyl Tn in Caco-2) were increased. Western blots of cell homogenates showed differences between KATO III and Caco-2 in MUC 1 apomucin protein antigens, in sialyl Lex and in sialyl Tn antigens. We conclude that benzyl-alpha-GalNAc does inhibit the glycosylation of mucin in KATO III gastric cancer cells as in human colon cancer cells, but that alterations in mucin antigens occur in a cell line-specific manner.
我们实验室之前的研究表明，苄基-α- N -乙酰半乳糖胺可抑制结肠癌细胞中粘蛋白的糖基化。在本研究中，我们确定苄基-α- N -乙酰半乳糖胺是否能抑制KATO III胃癌细胞中粘蛋白的糖基化。我们还检测了其对粘蛋白抗原表达的影响，并将KATO III产生的粘蛋白与结肠癌细胞系Caco-2产生的粘蛋白进行了比较。这些实验结果表明，苄基-α- N -乙酰半乳糖胺（2 mM）在KATO III细胞中使粘蛋白的[3H]葡萄糖胺标记减少了82%，在Caco-2细胞中减少了70%。对于这两种细胞系，在苄基-α- N -乙酰半乳糖胺存在下分泌的粘蛋白酸性较低。两种细胞系均分泌苄基寡糖，但KATO III分泌的苄基寡糖（8 - 9个糖）比Caco-2分泌的苄基寡糖（6 - 7个糖）更大。在从处理过的细胞培养基中纯化的粘蛋白中，外周碳水化合物抗原（KATO III中的唾液酸化路易斯抗原和Caco-2中的末端岩藻糖）减少（与对照相比），而核心碳水化合物抗原（两种细胞系中的T抗原和Caco-2中的唾液酸化Tn抗原）增加。细胞匀浆的蛋白质免疫印迹显示，KATO III和Caco-2在MUC 1脱辅基粘蛋白蛋白抗原、唾液酸化路易斯抗原和唾液酸化Tn抗原方面存在差异。我们得出结论，苄基-α- N -乙酰半乳糖胺确实如在人结肠癌细胞中一样，能抑制KATO III胃癌细胞中粘蛋白的糖基化，但粘蛋白抗原的改变以细胞系特异性方式发生。
