Inokuchi J, Jimbo M, Kumamoto Y, Shimeno H, Nagamatsu A
Department of Biochemistry, Faculty of Pharmaceutical Sciences, Fukuoka University, Japan.
Clin Exp Metastasis. 1993 Jan;11(1):27-36. doi: 10.1007/BF00880063.
In view of the evidence that cell expression of gangliosides in several tumors is positively involved in the metastatic phenotype, Lewis lung carcinoma (3LL) cell line, expressing GM3 as the major ganglioside, was analysed for the cell surface expression of GM3. An indirect immunofluorescence assay, using a M2590 monoclonal antibody recognizing GM3, was used for this purpose. Since the parental 3LL cells consist of heterogenous subpopulations differing in the degrees of GM3 expression, we have developed clones of this cell line with different degrees of metastatic potentials by using an in vitro non-selective procedure in order to investigate whether the expression of GM3 is associated with metastatic potential. The degree of cell surface expression of GM3 among the clones correlated well with their total cellular content of this ganglioside. However, we were unable to confirm the report of increased level of GM3 in high metastatic 3LL clones, nor did a decreased level correlate with weak metastatic ability. In our recent work, an inhibitor of glucosylceramide synthase, D-threo-1-phenyl-2-decanoylamino-3-morpholino-1-propanol (D-PDMP), was found to decrease the levels of all cellular glucosphingolipids and cause the accumulation of the precursors of glucosylceramide. The present study does not, however, rule out the possible involvement of this lipid family in metastatic dissemination, since treatment of 3LL cells with D-PDMP resulted in significant inhibition of their experimental metastatic potential. Clones expressing very low GM3 grew slowly in culture dishes, suggesting that GM3 may have a regulatory role in cell proliferation. The low metastatic clones expressed high levels of H-2Kb antigen, while the expression of the same antigen on the high metastatic clones was relatively low, confirming the previous observation of this tumor system. Moreover, a clone showing the lowest tumorigenic potency revealed both a high cell surface expression of H-2Kb and a high H-2Kb/H-2Db ratio.
鉴于有证据表明几种肿瘤中神经节苷脂的细胞表达与转移表型呈正相关，我们对以GM3为主要神经节苷脂的Lewis肺癌（3LL）细胞系进行了GM3细胞表面表达分析。为此，我们使用了一种间接免疫荧光测定法，该方法使用识别GM3的M2590单克隆抗体。由于亲本3LL细胞由GM3表达程度不同的异质亚群组成，我们通过体外非选择性程序开发了具有不同转移潜能程度的该细胞系克隆，以研究GM3的表达是否与转移潜能相关。各克隆中GM3的细胞表面表达程度与其该神经节苷脂的总细胞含量密切相关。然而，我们无法证实高转移3LL克隆中GM3水平升高的报道，低水平也与弱转移能力无关。在我们最近的工作中，发现葡糖神经酰胺合酶抑制剂D-苏式-1-苯基-2-癸酰氨基-3-吗啉代-1-丙醇（D-PDMP）可降低所有细胞糖鞘脂水平，并导致葡糖神经酰胺前体的积累。然而，本研究并不排除该脂质家族可能参与转移扩散，因为用D-PDMP处理3LL细胞会显著抑制其实验性转移潜能。表达极低GM3的克隆在培养皿中生长缓慢，这表明GM3可能在细胞增殖中具有调节作用。低转移克隆高水平表达H-2Kb抗原，而高转移克隆上该抗原的表达相对较低，这证实了此前对该肿瘤系统的观察结果。此外，一个显示出最低致瘤效力的克隆既表现出H-2Kb的高细胞表面表达，又表现出高的H-2Kb/H-2Db比值。
