Kawata Hirotoshi, Kamiakito Tomoko, Takayashiki Norio, Tanaka Akira
Department of Pathology, Jichi Medical University, Shimotsuke, Tochigi, Japan.
J Cell Physiol. 2006 Jun;207(3):793-9. doi: 10.1002/jcp.20618.
Active metabolites of vitamin A and D are well known to act as growth inhibitors in hormone-related prostate and breast cancers. When various concentrations of 1alpha,25-dihydroxyvitamin D3 (vitamin D3), all-trans-retinoic acid (ATRA) and 9-cis retinoic acid (9-cis RA) were examined, the androgen-stimulated growth of mouse mammary carcinoma SC-3 cells was inhibited by vitamin D3 alone in a dose-dependent manner. A flow cytometer analysis showed that vitamin D3 leads SC-3 cells to relative G1-growth arrest after 72 h. Characterization of vitamin D3-responsive genes using an oligonucleotide microarray demonstrated that 220 genes were upregulated at more than threefold, and 84 genes were downregulated to less than one-third, compared with the testosterone-stimulated SC-3 cells. Neither cyclin-dependent kinase inhibitors (CDKIs) nor the antiapoptotic bcl-2 gene were induced in vitamin D3-responsive genes, with the exception of a slight induction of p15(INK4B). Importantly, fgf8 was markedly repressed in response to vitamin D3. The exogenous addition of FGF8 canceled the growth suppression by vitamin D3 in SC-3 cells, suggesting that the repression of fgf8 is an indispensable step in vitamin D3-mediated growth inhibition. In reporter assays using the ARE-containing artificial construct and the natural androgen-regulated PSA promoter, co-transfection of the vitamin D receptor (VDR) and androgen receptor (AR) suppressed AR-stimulated promoter activity. In addition, vitamin D3 also suppressed androgen-stimulated promoter activity in the stably transfected SC-3 cells. Moreover, VDR repressed the core promoter activity of fgf8 in COS1 cells and in the SC-3 cells. All these findings strongly suggest that vitamin D3 serves as a negative regulator for both androgen-related and fgf8 transcriptions.
维生素A和D的活性代谢产物作为激素相关前列腺癌和乳腺癌的生长抑制剂广为人知。当检测不同浓度的1α,25 - 二羟基维生素D3（维生素D3）、全反式维甲酸（ATRA）和9 - 顺式维甲酸（9 - 顺式RA）时，维生素D3单独以剂量依赖方式抑制雄激素刺激的小鼠乳腺癌SC - 3细胞生长。流式细胞仪分析显示，72小时后维生素D3使SC - 3细胞进入相对G1期生长停滞。使用寡核苷酸微阵列对维生素D3反应性基因进行表征表明，与睾酮刺激的SC - 3细胞相比，220个基因上调超过三倍，84个基因下调至不到三分之一。除了p15(INK4B)有轻微诱导外，细胞周期蛋白依赖性激酶抑制剂（CDKIs）和抗凋亡bcl - 2基因在维生素D3反应性基因中均未被诱导。重要的是，fgf8对维生素D3有明显反应性抑制。在SC - 3细胞中外源添加FGF8可消除维生素D3对生长的抑制作用，这表明fgf8的抑制是维生素D3介导的生长抑制中不可或缺的一步。在使用含雄激素反应元件（ARE）的人工构建体和天然雄激素调节的前列腺特异性抗原（PSA）启动子的报告基因分析中，维生素D受体（VDR）和雄激素受体（AR）共转染可抑制AR刺激的启动子活性。此外，维生素D3在稳定转染的SC - 3细胞中也抑制雄激素刺激的启动子活性。而且，VDR在COS1细胞和SC - 3细胞中均抑制fgf8的核心启动子活性。所有这些发现强烈表明，维生素D3是雄激素相关转录和fgf8转录的负调节因子。
