Poulin Hugo, Filion Christine, Ladanyi Marc, Labelle Yves
Human and Molecular Genetic Research Unit, Saint-François d'Assise Hospital, CHUQ, Que., Canada G1L 3L5.
Biochem Biophys Res Commun. 2006 Jul 21;346(1):306-13. doi: 10.1016/j.bbrc.2006.05.134. Epub 2006 Jun 2.
The NR4A3 nuclear receptor (also known as NOR1) is involved in tumorigenesis by the t(9;22) chromosome translocation encoding the EWS/NOR1 fusion protein found in approximately 75% of all cases of extraskeletal myxoid chondrosarcomas (EMC). Several observations suggest that one role of EWS/NOR1 in tumorigenesis may be to deregulate the expression of specific target genes. We have shown previously that constitutive expression of EWS/NOR1 in CFK2 fetal rat chondrogenic cells induces their transformation as measured by growth beyond confluency and growth in soft agar. To identify genes regulated by the fusion protein in this model, we have generated a CFK2 cell line in which the expression of EWS/NOR1 is controlled by tetracycline. Using the differential display technique, we have identified the serum- and glucocorticoid-regulated kinase 1 (SGK1) mRNA as being up-regulated in the presence of EWS/NOR1. Co-immunocytochemistry confirmed over-expression of the SGK1 protein in cells expressing EWS/NOR1. Significantly, immunohistochemistry of 10 EMC tumors positive for EWS/NOR1 showed that all of them over-express the SGK1 protein in contrast to non-neoplastic cells in the same biopsies and various other sarcoma types. These results strongly suggest that SGK1 may be a genuine in vivo target of EWS/NOR1 in EMC.
核受体NR4A3（也称为NOR1）通过9号和22号染色体易位参与肿瘤发生，该易位编码EWS/NOR1融合蛋白，在约75%的骨外黏液样软骨肉瘤（EMC）病例中可发现这种融合蛋白。多项观察结果表明，EWS/NOR1在肿瘤发生中的一个作用可能是解除特定靶基因表达的调控。我们之前已表明，在CFK2胎鼠软骨生成细胞中组成型表达EWS/NOR1会诱导其发生转化，这可通过汇合后生长及软琼脂中生长来衡量。为了在该模型中鉴定受融合蛋白调控的基因，我们构建了一种CFK2细胞系，其中EWS/NOR1的表达受四环素控制。利用差异显示技术，我们鉴定出血清和糖皮质激素调节激酶1（SGK1）mRNA在存在EWS/NOR1时上调。共免疫细胞化学证实了在表达EWS/NOR1的细胞中SGK1蛋白过表达。重要的是，对10例EWS/NOR1呈阳性的EMC肿瘤进行免疫组织化学分析显示，与同一活检组织中的非肿瘤细胞及其他各种肉瘤类型相比，所有这些肿瘤均过表达SGK1蛋白。这些结果强烈表明，SGK1可能是EMC中EWS/NOR1真正的体内靶标。
