Yamashiro S, Okada M, Haraguchi M, Furukawa K, Lloyd K O, Shiku H, Furukawa K
Department of Oncology, Nagasaki University School of Medicine, Japan.
Glycoconj J. 1995 Dec;12(6):894-900. doi: 10.1007/BF00731251.
GD3 Synthase (alpha 2,8sialyltransferase) (EC 2.4.99.8) cDNA has been cloned by eukaryotic cell expression cloning. Using this cDNA as a probe, the expression level of the gene in human cancer cell lines was analysed by Northern blotting and RT-PCR, then correlated with the ganglioside expression and enzyme activity. Melanoma cell lines showed extremely strong bands in Northern blot and RT-PCR/Southern analysis. The enzyme activity was also very high in melanomas as expected. Neuroblastoma and astrocytoma lines showed relatively low levels of the gene expression, whereas they expressed high levels of GD2. Although the mRNA level of the GD3 synthase gene and enzyme activity in individual cell lines correlated positively, some cell lines showed much higher activity than expected from the mRNA level. Among leukaemia lines, adult T cell leukaemia-associated (HTLV-I+) lines showed fairly high levels of the mRNA. On the other hand, T-ALL lines showed very low levels. In addition, GD3 and GD2 expression and mRNA level of the gene during T lymphocyte activation were analysed. Only GD3 expression was induced by any of the stimulatory reagents used, and corresponding up-regulation of the GD3 synthase gene was shown in RT-PCR/Southern analysis.
GD3合酶（α2,8-唾液酸转移酶）（EC 2.4.99.8）的互补DNA（cDNA）已通过真核细胞表达克隆法克隆出来。以该cDNA为探针，通过Northern印迹法和逆转录聚合酶链反应（RT-PCR）分析了该基因在人癌细胞系中的表达水平，然后将其与神经节苷脂表达及酶活性相关联。黑色素瘤细胞系在Northern印迹以及RT-PCR/ Southern分析中显示出极强的条带。正如预期的那样，黑色素瘤中的酶活性也非常高。神经母细胞瘤和星形细胞瘤细胞系显示出相对较低水平的基因表达，然而它们却表达高水平的GD2。尽管各个细胞系中GD3合酶基因的信使核糖核酸（mRNA）水平与酶活性呈正相关，但一些细胞系显示出的活性比根据mRNA水平预期的要高得多。在白血病细胞系中，成人T细胞白血病相关（HTLV-I阳性）细胞系显示出相当高水平的mRNA。另一方面，T细胞急性淋巴细胞白血病（T-ALL）细胞系显示出极低的水平。此外，还分析了T淋巴细胞激活过程中GD3和GD2的表达以及该基因的mRNA水平。在所使用的任何刺激试剂中，只有GD3的表达被诱导，并且在RT-PCR/ Southern分析中显示出GD3合酶基因相应的上调。
