GFAP GENE EXPRESSION IN HUMAN GLIOMA CELL

我们通过连续传代GFAP阳性的人胶质瘤细胞系，采用免疫组织化学和Northern blot杂交技术分析了GFAP的表达。在一个细胞系（病例1）中，培养的细胞从传代早期到传代后期均稳定表达GFAP蛋白和mRNA。在另一个细胞系（病例2）中，GFAP表达不太稳定。在传代早期，几乎100%的培养细胞表现出强烈的GFAP免疫反应性。然而，传代30次后，GFAP弱阴性染色细胞逐渐增多，传代100次时，几乎所有细胞GFAP均为阴性。在连续传代过程中，从该细胞系分离的7个GFAP阳性克隆在传代30和50时也观察到GFAP免疫反应性的类似变化，这表明每个细胞都有减少并最终停止其GFAP表达的趋势。Northern blot研究显示，GFAP mRNA在亲本和克隆细胞系中也同时发生变化，表明在转录水平上发生了调控变化。应用原位杂交技术对1例星形细胞瘤和1例间变性胶质瘤的组织中GFAP mRNA进行了分析。从3′非编码区选择GFAP cDNA特异性反义寡聚物。使用低强度探针对胶质瘤细胞系进行Northern blot杂交，显示出3.4 kb的条带。GFAP mRNA特异性阳性颗粒分布在正常小脑的Bergmann胶质细胞和星形细胞瘤组织中，而在间变性胶质瘤组织中不存在。

We have analyzed GFAP expression through successive passages of GFAP-positive human glioma cell line by using the immunohistochemistry and Northern blot hybridization. In one cell line (Case 1), the cultured cells showed stable expression of GFAP protein and mRNA from early to later passage levels. In the other cell line (Case 2), GFAP expression was shown to be less stable. At early passage, nearly 100% of the cultured cells displayed intense GFAP immunoreactivity. After passage 30, however, weakly to negatively stained cells increased gradually in number, and by passage 100, almost all cells had become negative for GFAP. A similar change in GFAP immunoreactivity during successive passages was also observed in each of 7 GFAP-positive clones isolated from this cell line at passage 30 and 50, suggesting that each cell had a tendency to reduce and finally stop its GFAP expression. Northern blot studies revealed that GFAP mRNA also change concomitantly in the parental and clonal cell lines, suggesting a regulatory change at the transcriptional level.GFAP mRNA have been analyzed in materials of one astrocytoma case, and of one anaplastic glioma case using in situ hybridization technique. Anti-sense oligomer specific for GFAP cDNA was selected from 3' non-coding region. The use of this probe with low stringency showed 3.4-kb band in human glioma cell lines by Northern blot hybridization. The positive grains specific for GFAP mRNA were distributed in Bergmann's glia in normal cerebellum, and in astrocytoma tissues, but not in anaplastic glioma tissues.