MacArthur C A, Lawshé A, Shankar D B, Heikinheimo M, Shackleford G M
Department of Pediatrics, Washington University School of Medicine, St. Louis, Missouri 63110, USA.
Cell Growth Differ. 1995 Jul;6(7):817-25.
We previously identified Fgf-8 as a frequently activated gene in tumors from mouse mammary tumor virus-infected Wnt-1 transgenic mice, suggesting that Fgf-8 is a proto-oncogene. We further determined that multiple, secreted protein isoforms that differ at their mature amino termini are encoded by alternatively spliced mRNAs transcribed from the gene. We now present evidence that there are differences in the potency of NIH3T3 cell transformation displayed by three of the FGF (fibroblast growth factor)-8 isoforms. We find that stable transfection of a cDNA for the FGF-8b isoform leads to marked morphological transformation of NIH3T3 cells and rapid tumorigenicity of the transfected cells in nude mice. In contrast, transfection of a cDNA for the FGF-8a or FGF-8c isoform results in moderate morphological changes in the NIH3T3 cells, and the transfected cells are weakly tumorigenic in nude mice. All three transfections result in cells that express comparable amounts of Fgf-8 mRNA and that produce the FGF-8 protein isoforms. The morphological changes observed in NIH3T3 cells can be reproduced by the addition of recombinant FGF-8 protein isoforms to the culture medium. Therefore, these results indicate that there are differences in the potency of transformation of NIH3T3 cells by FGF-8 protein isoforms and suggest that these FGF-8 isoforms may have different in vivo functions.
我们之前鉴定出Fgf-8是感染小鼠乳腺肿瘤病毒的Wnt-1转基因小鼠肿瘤中频繁激活的基因，这表明Fgf-8是一种原癌基因。我们进一步确定，该基因转录的可变剪接mRNA编码了多种在成熟氨基末端不同的分泌型蛋白质异构体。我们现在提供证据表明，三种FGF（成纤维细胞生长因子）-8异构体在NIH3T3细胞转化能力上存在差异。我们发现，FGF-8b异构体的cDNA稳定转染导致NIH3T3细胞发生明显的形态转化，且转染细胞在裸鼠中具有快速致瘤性。相比之下，FGF-8a或FGF-8c异构体的cDNA转染导致NIH3T3细胞出现中度形态变化，且转染细胞在裸鼠中的致瘤性较弱。所有三种转染都导致细胞表达相当数量的Fgf-8 mRNA并产生FGF-8蛋白质异构体。通过向培养基中添加重组FGF-8蛋白质异构体，可以重现NIH3T3细胞中观察到的形态变化。因此，这些结果表明FGF-8蛋白质异构体在转化NIH3T3细胞的能力上存在差异，并表明这些FGF-8异构体可能具有不同的体内功能。
