Zhuang S H, Schwartz G G, Cameron D, Burnstein K L
Department of Molecular Pharmacology, University of Miami School of Medicine, FL 33136, USA.
Mol Cell Endocrinol. 1997 Jan 3;126(1):83-90. doi: 10.1016/s0303-7207(96)03974-3.
Prostate cancer cell lines exhibit variable growth suppression by the hormonal form of vitamin D3, 1,25-Dihydroxyvitamin D3 [1,25 (OH)2D] (1,25 D3). To understand the molecular basis for this differential sensitivity to 1,25 D3, we compared growth response to 1,25 d3, vitamin D receptor (VDR) content and VDR transcriptional activity in four well-characterized human prostate cancer cell lines: LNCaP, DU145, PC-3 and ALVA-31. In PC-3 and DU145 cells, relative lack of growth inhibition by 1,25 D3 (< 10% inhibition) correlates with very low levels of VDR (9-15 fmol/mg protein) compared to classical vitamin D3 target tissues (approximately 75-200 fmol/mg protein). Transfection of DU145 and PC-3 cells with a VDR cDNA expression vector is sufficient to establish growth sensitivity to 1,25 D3, suggesting that low VDR levels are responsible for the failure of these cell lines to respond to 1,24 D3. LNCaP cells are highly sensitive to growth inhibition by 1.25 D3 (approximately 55% inhibition) and contain approximately 2-3-fold more VDR (25 fmol/mg) than the relatively 1,25 D3-insensitive PC-3 and DU145 cell lines. However, ALVA-31 cells display less than 20% growth inhibition to 1.25 D3 although they contain the highest levels of VDR (45 fmol/mg) of the four cell lines. Thus, sensitivity to growth inhibition by 1,25 D3 does not correlate with VDR content in ALVA-31 and LNCaP cells. This lack of correlation between VDR density and growth responses to 1,25 D3 led us to investigate VDR-mediated gene transcription in these cell lines. We employed two different naturally occurring vitamin D response elements (VDREs) linked to a reporter gene. Reporter gene activation by 1,25 D3 correlated well with VDR content in all four cell lines. Therefore, compared to LNCaP cells, decreased sensitivity of ALVA-31 to growth inhibition by 1,25 D3 is not due to a decrease in the general transcriptional activity of VDR. We conclude that growth inhibition by 1,25 D3 in prostate cancer cells requires VDR but that this response is modulated by non-receptor factors that are cell line-specific.
前列腺癌细胞系对激素形式的维生素D3，即1,25 - 二羟基维生素D3 [1,25(OH)2D]（1,25 D3）表现出不同程度的生长抑制。为了了解这种对1,25 D3敏感性差异的分子基础，我们比较了四种特征明确的人前列腺癌细胞系：LNCaP、DU145、PC - 3和ALVA - 31对1,25 D3的生长反应、维生素D受体（VDR）含量及VDR转录活性。在PC - 3和DU145细胞中，1,25 D3相对缺乏生长抑制作用（抑制率<10%），与经典维生素D3靶组织（约75 - 200 fmol/mg蛋白）相比，其VDR水平非常低（9 - 15 fmol/mg蛋白）。用VDR cDNA表达载体转染DU145和PC - 3细胞足以使其对1,25 D3产生生长敏感性，这表明低VDR水平是这些细胞系对1,25 D3无反应的原因。LNCaP细胞对1,25 D3的生长抑制高度敏感（约55%抑制），其VDR含量（25 fmol/mg）比相对不敏感的PC - 3和DU145细胞系多约2 - 3倍。然而，ALVA - 31细胞对1,25 D3的生长抑制率小于20%，尽管它们在这四种细胞系中VDR水平最高（45 fmol/mg）。因此，ALVA - 31和LNCaP细胞对1,25 D3生长抑制的敏感性与VDR含量无关。VDR密度与对1,25 D3的生长反应之间缺乏相关性，这促使我们研究这些细胞系中VDR介导的基因转录。我们使用了两种与报告基因相连的天然存在的维生素D反应元件（VDREs）。1,25 D3对报告基因的激活在所有四种细胞系中与VDR含量密切相关。因此，与LNCaP细胞相比，ALVA - 31对1,25 D3生长抑制敏感性降低并非由于VDR的一般转录活性降低。我们得出结论，前列腺癌细胞中1,25 D3的生长抑制需要VDR，但这种反应受细胞系特异性的非受体因子调节。
