Takayashiki Norio, Kawata Hirotoshi, Kamiakito Tomoko, Tanaka Akira
Department of Pathology, Jichi Medical School, 3311-1 Yakushiji, Minamikawachi, Kawachi, Tochigi 329-0498, Japan.
J Steroid Biochem Mol Biol. 2005 Jun;96(1):1-12. doi: 10.1016/j.jsbmb.2005.01.031.
We here characterized the transcriptional profiles of TGF-beta-responsive genes using androgen-dependent mouse mammary carcinoma SC-3 cells. Compared with the testosterone-stimulated SC-3 cells, 165 genes were up-regulated at more than 5-fold, and 78 genes were down-regulated to less than one-third in response to TGF-beta. Of note, fgf8, an androgen-inducible growth factor essential to the androgen-dependent growth of SC-3 cells, was severely repressed in response to TGF-beta. Real-time PCR confirmed that the androgenic induction of the fgf8 transcripts is severely attenuated by TGF-beta. Although a considerable number of growth-suppressive genes were up-regulated in response to TGF-beta, the treatment with TGF-beta was insufficient to lead SC-3 cells to apoptosis within 24h by both the TUNEL method and the caspase 3 activity assay. Flow cytometric analysis rather indicated the cell-static effect of TGF-beta on the androgen-stimulated SC-3 cells. In addition, TGF-beta failed to suppress the FGF8-stimulated growth of SC-3 cells, suggesting that the repression of fgf8 is required for the TGF-beta-mediated growth inhibition in SC-3 cells. In a reporter assay, androgen-responsive promoter activity was suppressed by TGF-beta in SC-3 cells. Based on this finding, it is likely that some of the androgen-inducible genes are physiological targets of the TGF-beta-mediated transcriptional control, and therefore, it is strongly suggested that the repression of fgf8 might be directly or indirectly involved in this transcriptional control by TGF-beta.
我们在此利用雄激素依赖性小鼠乳腺癌SC-3细胞对转化生长因子β（TGF-β）反应性基因的转录谱进行了表征。与睾酮刺激的SC-3细胞相比，有165个基因上调超过5倍，78个基因在TGF-β作用下下调至不到三分之一。值得注意的是，成纤维细胞生长因子8（fgf8）是一种对SC-3细胞雄激素依赖性生长至关重要的雄激素诱导生长因子，在TGF-β作用下受到严重抑制。实时聚合酶链反应（PCR）证实，TGF-β严重减弱了fgf8转录本的雄激素诱导作用。尽管有相当数量的生长抑制基因在TGF-β作用下上调，但通过TUNEL法和半胱天冬酶3活性测定法，TGF-β处理在24小时内不足以使SC-’3细胞发生凋亡。流式细胞术分析反而表明TGF-β对雄激素刺激的SC-3细胞具有细胞静止作用。此外，TGF-β未能抑制FGF8刺激的SC-3细胞生长，这表明在SC-3细胞中，TGF-β介导的生长抑制需要fgf8的抑制。在报告基因检测中，TGF-β抑制了SC-3细胞中雄激素反应性启动子的活性。基于这一发现，一些雄激素诱导基因很可能是TGF-β介导的转录调控的生理靶点，因此，强烈提示fgf8的抑制可能直接或间接参与了TGF-β的这种转录调控。
