Schwartz R, Schirrmacher V, Mühlradt P F
Int J Cancer. 1984 Apr 15;33(4):503-9. doi: 10.1002/ijc.2910330414.
Since various experimental findings point towards an important role of cell surface carbohydrates - in particular sialic acid - in cancer metastasis, the rationale of this study was to look for possible differences in carbohydrate metabolism and glycoprotein expression in well-defined related tumor lines of different metastatic capacity. The tumor lines analyzed were L5178Y E (= Eb), a low-metastasizing, methylcholanthrene-induced lymphoma of a DBA/2 mouse, and L5178Y ES (= ESb), a spontaneous high-metastatic variant thereof. A non-related, highly metastasizing tumor, MDAY-D2, and ConA-stimulated spleen cells were included in the study. These cell lines were compared for incorporation rates of various labelled carbohydrates and for glycoprotein patterns in SDS-polyacrylamide gels. Marked differences were observed in the incorporation of 3H-fucose, while the incorporation of 3H-galactose and 3H-mannose was similar in the different cell lines studied. Only the metastatic variant ESb incorporated 3H-fucose at a rate similar to that of ConA-stimulated T-cell blasts. Eb cells did not incorporate 3H-fucose while MDAY-D2 had a significantly lower 3H-fucose incorporation rate. Separation and purification of the intracellular products of 3H-fucose by gel filtration and high-voltage electrophoresis revealed in Eb cells a block in the synthesis of fucosylated glycoproteins at the step of the fucose-I-P-guanylyltransferase. No apparent defect in the fucose pathway was detectable in MDAY-D2 cells. An Eb----ESb shifted cell line regained the ability to incorporate 3H-fucose. All tumors displayed unique glycoprotein patterns in SDS-PAGE. Labelling with 3H-mannose revealed the most distinct bands, while labelling with 3H-galactose gave fewer and broader bands. Although clonal instability of metastasizing tumor variants has been frequently reported, subclones of Eb and ESb showed characteristics similar to those of the original cell lines with regard to metastatic capacity, fucose metabolism and glycoprotein expression. These results will be discussed in relation to differences in fucose metabolism and in surface expression of fucose as observed in other tumor systems consisting of high- and low-metastatic lines.
由于各种实验结果表明细胞表面碳水化合物——尤其是唾液酸——在癌症转移中起重要作用，本研究的目的是寻找具有不同转移能力的明确相关肿瘤细胞系在碳水化合物代谢和糖蛋白表达方面可能存在的差异。所分析的肿瘤细胞系包括L5178Y E（= Eb），一种由甲基胆蒽诱导的、低转移的DBA/2小鼠淋巴瘤，以及其自发的高转移变体L5178Y ES（= ESb）。研究中还包括一个不相关的高转移肿瘤MDAY-D2和伴刀豆球蛋白A刺激的脾细胞。比较了这些细胞系对各种标记碳水化合物的掺入率以及SDS-聚丙烯酰胺凝胶中的糖蛋白图谱。在3H-岩藻糖的掺入方面观察到显著差异，而在所研究的不同细胞系中，3H-半乳糖和3H-甘露糖的掺入情况相似。只有转移变体ESb以与伴刀豆球蛋白A刺激的T细胞母细胞相似的速率掺入3H-岩藻糖。Eb细胞不掺入3H-岩藻糖，而MDAY-D2的3H-岩藻糖掺入率明显较低。通过凝胶过滤和高压电泳对3H-岩藻糖的细胞内产物进行分离和纯化后发现，Eb细胞在岩藻糖基化糖蛋白合成过程中，在岩藻糖-1-磷酸-鸟苷转移酶步骤出现阻断。在MDAY-D2细胞中未检测到岩藻糖途径有明显缺陷。一个从Eb转变为ESb的细胞系恢复了掺入3H-岩藻糖的能力。所有肿瘤在SDS-PAGE中均显示出独特的糖蛋白图谱。用3H-甘露糖标记显示出最清晰的条带，而用3H-半乳糖标记得到的条带较少且较宽。尽管经常报道转移肿瘤变体的克隆不稳定性，但Eb和ESb的亚克隆在转移能力、岩藻糖代谢和糖蛋白表达方面表现出与原始细胞系相似的特征。这些结果将与在由高转移和低转移细胞系组成的其他肿瘤系统中观察到的岩藻糖代谢差异以及岩藻糖的表面表达差异相关联进行讨论。
