Sawada M, Moriya S, Shineha R, Satomi S, Miyagi T
Division of Biochemistry, Research Institute, Miyagi Prefectural Cancer Center, Natori, Japan.
Acta Biochim Pol. 1998;45(2):343-9.
We previously demonstrated that transfection of a sialidase cDNA into B16-BL6 cells, a highly metastatic and invasive cell line derived from the mouse B16 melanoma, resulted in a marked suppression of metastasis accompanied by decreased cellular content of the GM3 that is one of the target molecules of the sialidase expressed (Tokuyama et al., 1997 Int. J. Cancer, 73, 410-415). To obtain further insight into the involvement of sialidase in metastasis, we made a comparison of the levels of sialidase activity and GM3 content between B16 melanoma cell lines with low (B16-F1) and high (B16-F10 and -BL6) metastatic potential. The cells exhibited sialidase activity towards 4-methylumbelliferyl N-acetylneuraminic acid (4MU-Neu5Ac) and gangliosides at acidic pH in the particulate fractions, but not in the cytosol. The activity toward 4MU-NeuAc was significantly lower in highly metastatic cells. The activity toward gangliosides, on the other hand, varied independently of metastatic potential: B16-F10 cells with a high potential for experimental metastasis showed the lowest level and B16-BL6 cells having high invasiveness had rather a higher level of ganglioside sialidase along with a much greater GM3 synthase activity than the other two cell lines. Flow cytometric analysis with anti-GM3 antibody revealed that highly metastatic cell lines were higher in the binding affinity as compared to B16-F1 cells, B16-BL6 cells containing twice as much cellular GM3 as B16-F1 cells on thin-layer chromatography.
我们先前证明，将唾液酸酶cDNA转染到B16-BL6细胞（一种源自小鼠B16黑色素瘤的高转移性和侵袭性细胞系）中，会导致转移显著受到抑制，同时唾液酸酶表达的靶分子之一GM3的细胞含量降低（Tokuyama等人，1997年，《国际癌症杂志》，73卷，410 - 415页）。为了进一步深入了解唾液酸酶在转移中的作用，我们比较了低转移潜力（B16-F1）和高转移潜力（B16-F10和-BL6）的B16黑色素瘤细胞系之间的唾液酸酶活性水平和GM3含量。细胞在酸性pH条件下，在微粒部分对4-甲基伞形酮基N-乙酰神经氨酸（4MU-Neu5Ac）和神经节苷脂表现出唾液酸酶活性，但在胞质溶胶中没有。高转移性细胞对4MU-NeuAc的活性显著较低。另一方面，对神经节苷脂的活性与转移潜力无关：具有高实验转移潜力的B16-F10细胞显示出最低水平，而具有高侵袭性的B16-BL6细胞与其他两个细胞系相比，神经节苷脂唾液酸酶水平较高，同时GM3合酶活性也高得多。用抗GM3抗体进行的流式细胞术分析表明，与B16-F1细胞相比，高转移性细胞系具有更高的结合亲和力，在薄层色谱上，B16-BL6细胞的细胞GM3含量是B16-F1细胞的两倍。
