Schwartz G G, Whitlatch L W, Chen T C, Lokeshwar B L, Holick M F
Sylvester Comprehensive Cancer Center and Department of Epidemiology & Public Health, University of Miami School of Medicine, Florida 33101, USA.
Cancer Epidemiol Biomarkers Prev. 1998 May;7(5):391-5.
Epidemiological and laboratory data support a role for vitamin D in the growth and differentiation of human prostatic cells. These findings prompted us to ask whether prostatic cells could convert 25-hydroxyvitamin D3 (25-OH-D3), the major circulating metabolite of vitamin D3, to 1,25-dihydroxyvitamin D3 [1,25(OH)2D3], the hormonally active metabolite, in a manner similar to cultured human keratinocytes. Therefore, we investigated three well-characterized human prostate cancer cell lines, LNCaP, DU 145, and PC-3; two primary cultures of cells derived from noncancerous human prostates (one normal and one benign prostatic hyperplasia); and primary cultures of normal human keratinocytes for their ability to synthesize 1,25(OH)2D3. Assays were performed in the presence of 25-OH-D3 as the enzyme substrate and 1,2-dianilinoethane, an antioxidant and free radical scavenger, and in the presence and absence of clotrimazole, a cytochrome P450 inhibitor. DU 145 and PC-3 cells produced 0.31 +/- 0.06 and 0.07 +/- 0.01 pmol of 1,25(OH)2D3/mg protein/h, respectively. No measurable 1,25(OH)2D3 was detected in LNCaP cells. The normal and benign prostatic hyperplasia primary cultures and keratinocyte cultures produced 3.08 +/- 1.56, 1.05 +/- 0.31, and 2.1 +/- 0.1 pmol of 1,25(OH)2D3/mg protein/h, respectively, using a calf thymus receptor binding assay to measure 1,25(OH)2D3 in the presence of 1,2-dianilinoethane. The identity of the analyte as 1,25(OH)2D3 was supported by high performance liquid chromatography using [3H]25-OH-D3 as the enzyme substrate and a solvent system that is specific for 1,25(OH)2D3. The production of 1,25(OH)2D3 in the prostate cancer cell lines and in the primary cultures was completely inhibited in the presence of clotrimazole. This report demonstrates that two of three human prostate cancer cell lines, as well as primary cultures of noncancerous prostatic cells, possess 1alpha-hydroxylase activity and can synthesize 1,25(OH)2D3 from 25-OH-D3. Together with recent data indicating that 1,25(OH)2D3 inhibits the invasiveness of human prostate cancer cells (G. G. Schwartz et al., Cancer Epidemiol. Biomark. Prev., 6: 727-732, 1997), these data suggest a potential role for 25-OH-D3 in the chemoprevention of invasive prostate cancer.
流行病学和实验室数据支持维生素D在人前列腺细胞生长和分化中发挥作用。这些发现促使我们探究前列腺细胞是否能够像培养的人角质形成细胞一样，将维生素D3的主要循环代谢物25-羟基维生素D3（25-OH-D3）转化为具有激素活性的代谢物1,25-二羟基维生素D3 [1,25(OH)2D3]。因此，我们研究了三种特性明确的人前列腺癌细胞系LNCaP、DU 145和PC-3；两种源自非癌性人前列腺的原代细胞培养物（一种正常，一种良性前列腺增生）；以及正常人角质形成细胞合成1,25(OH)2D3的能力。实验在以25-OH-D3作为酶底物以及1,2-二苯胺乙烷（一种抗氧化剂和自由基清除剂）存在的情况下进行，并且在有和没有克霉唑（一种细胞色素P450抑制剂）存在的情况下进行。DU 145和PC-3细胞分别产生0.31±0.06和0.07±0.01 pmol的1,25(OH)2D3/毫克蛋白/小时。在LNCaP细胞中未检测到可测量的1,25(OH)2D3。使用小牛胸腺受体结合测定法在1,2-二苯胺乙烷存在的情况下测量1,25(OH)2D3，正常和良性前列腺增生原代培养物以及角质形成细胞培养物分别产生3.08±1.56、1.05±0.31和2.1±0.1 pmol的1,25(OH)2D3/毫克蛋白/小时。使用[3H]25-OH-D3作为酶底物以及对1,25(OH)2D3具有特异性的溶剂系统，通过高效液相色谱法证实了分析物为1,25(OH)2D3。在克霉唑存在的情况下，前列腺癌细胞系和原代培养物中1,25(OH)2D3的产生被完全抑制。本报告表明，三种人前列腺癌细胞系中的两种以及非癌性前列腺细胞的原代培养物具有1α-羟化酶活性，并且能够从25-OH-D3合成1,25(OH)2D3。连同最近的数据表明1,25(OH)2D3抑制人前列腺癌细胞的侵袭性（G.G.施瓦茨等人，《癌症流行病学、生物标志物与预防》，6: 727 - 732, 1997），这些数据表明25-OH-D3在侵袭性前列腺癌的化学预防中可能发挥作用。
