Tissue specific metabolism of 1alpha,25-dihydroxy-20-epi-vitamin D3 into new metabolites with significant biological activity: studies in rat osteosarcoma cells (UMR 106 and ROS 17/2.8).
Tissue specific metabolism of 1alpha,25-dihydroxy-20-epi-vitamin D3 into new metabolites with significant biological activity: studies in rat osteosarcoma cells (UMR 106 and ROS 17/2.8).
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1α,25-二羟基-20-表维生素 D3 的组织特异性代谢为具有显着生物活性的新代谢物：大鼠骨肉瘤细胞的研究（UMR 106 和 ROS 17/2.8）。
DOI：
10.1002/jcb.1189
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发表时间：
2001
影响因子：
4
通讯作者：
Reddy,GS
中科院分区：
文献类型：
--
作者：
Siu-Caldera,ML;Rao,DS;Astecker,N;Weiskopf,A;Vouros,P;Konno,K;Fujishima,T;Takayama,H;Peleg,S;Reddy,GS
在最近的一项研究中，我们研究了 1α, 25-二羟基-20-epi-维生素 D3 (1α, 25 (OH) 2-20-epi-D3)（一种强效合成维生素 D3 类似物）在离体灌注大鼠肾脏中的代谢，并提出 1α, 25 (OH) 2-20-epi-D3 增强的生物活性部分归因于其代谢为稳定的生物活性中间代谢物通过C-24氧化途径(Siu-Caldera等人[1999] J. Steroid. Biochem. Mol. Biol. 71: 111±121)。现在已经确定，1α, 25 (OH) 2D3 及其类似物在靶组织中不仅通过 C-24 氧化途径代谢，还通过 C-3 差向异构化途径代谢。由于灌注的大鼠肾脏不表达 C-3 差向异构化途径，因此我们无法鉴定通过 C-3 差向异构化途径衍生的 1α, 25 (OH) 2-20-epi-D3 其他可能的生物活性代谢物，例如 1α, 25 (OH) 2-20-epi-3-epi-D3。因此，我们研究了 1α, 25 (OH) 2-20-epi-D3 在表达 C-24 氧化和 C-3 差向异构化途径的大鼠骨肉瘤细胞 (UMR 106) 中的代谢。我们的结果表明，1α, 25 (OH) 2-20-epi-D3 在 UMR 106 细胞中代谢成多种代谢物，其中不仅包括先前已知的 C-24 氧化途径代谢物，还包括标记为代谢物 X、Y1 和 Y2 的三种新代谢物。代谢物 X 明确鉴定为 1α, 25 (OH) 2-20-epi-3-epi-D3。尽管我们目前的研究尚未对代谢物 Y1 和 Y2 进行明确的结构鉴定，但我们确定代谢物 Y1 由 1α, 25 (OH) 2-20-epi-D3 产生，代谢物 Y2 由 1α, 25 (OH) 2-20-epi-3-epi-D3 产生。我们还注意到在不同的大鼠骨肉瘤细胞 (ROS 17/2.8) 中产生 1α, 25 (OH) 2-20-epi-3-epi-D3 以及两种代谢物 Y1 和 Y2，这些细胞仅表达 C-3 差向异构化途径，而不表达 C-24 氧化途径。此外，我们在早期研究中研究了离体灌注大鼠肾中 1α, 25 (OH) 2-20-epi-D3 的代谢。这项研究的结果表明，与大鼠骨肉瘤细胞不同，大鼠肾脏不产生 1α, 25 (OH) 2-20-epi-3-epi-D3 或代谢物 Y1 和 Y2。因此，代谢物 Y1 和 Y2，如 1α, 25 (OH) 2-20-epi-3-epi-D3，似乎仅在特定组织中产生。通过测量其产生 VDR 介导的基因转录的能力来评估每种新代谢物的初步生物活性。发现 1α, 25 (OH) 2-20-epi-3-epi-D3 几乎与 1α, 25 (OH) 2-20-epi-D3 等价，而代谢物 Y1 和 Y2 活性较低。代谢物 Y1 与代谢物 Y2 相比
In a recent study, we investigated the metabolism of 1α, 25-dihydroxy-20-epi-vitamin D3 (1α, 25 (OH) 2-20-epi-D3), a potent synthetic vitamin D3 analog in the isolated perfused rat kidney and proposed that the enhanced biological activity of 1α, 25 (OH) 2-20-epi-D3 is in part due to its metabolism into stable bioactive intermediary metabolites derived via the C-24 oxidation pathway (Siu-Caldera et al.[1999] J. Steroid. Biochem. Mol. Biol. 71: 111±121). It is now well established that 1α, 25 (OH) 2D3 and its analogs are metabolized in target tissues not only via the C-24 oxidation pathway but also via the C-3 epimerization pathway. As the perfused rat kidney does not express the C-3 epimerization pathway, we could not identify other possible bioactive metabolites of 1α, 25 (OH) 2-20-epi-D3 such as 1α, 25 (OH) 2-20-epi-3-epi-D3, derived via the C-3 epimerization pathway. Therefore, we studied the metabolism of 1α, 25 (OH) 2-20-epi-D3 in rat osteosarcoma cells (UMR 106) which express both the C-24 oxidation and the C-3 epimerization pathways. Our results indicate that 1α, 25 (OH) 2-20-epi-D3 is metabolized in UMR 106 cells into several metabolites which included not only the previously known metabolites of the C-24 oxidation pathway but also three new metabolites which were labeled as metabolites X, Y1, and Y2. Metabolite X was unequivocally identi® ed as 1α, 25 (OH) 2-20-epi-3-epi-D3. Eventhough de® nite structure identi® cation of the metabolites, Y1 and Y2 was not achieved in our present study, we determined that the metabolite Y1 is produced from 1α, 25 (OH) 2-20-epi-D3 and the metabolite Y2 is produced from 1α, 25 (OH) 2-20-epi-3-epi-D3. We also noted the production of both 1α, 25 (OH) 2-20-epi-3-epi-D3 and the two metabolites Y1 and Y2 in different rat osteosarcoma cells (ROS 17/2.8) which express only the C-3 epimerization pathway but not the C-24 oxidation pathway. Furthermore, we investigated the metabolism of 1α, 25 (OH) 2-20-epi-D3 in the isolated perfused rat kidney in an earlier study. The results of this study indicated that the rat kidney unlike rat osteosarcoma cells did not produce either 1α, 25 (OH) 2-20-epi-3-epi-D3 or the metabolites Y1 and Y2. Thus, it appears that the metabolites Y1 and Y2, like 1α, 25 (OH) 2-20-epi-3-epi-D3, are produced only in speci® c tissues. Preliminary biological activity of each new metabolite is assessed by measuring its ability to generate VDR-mediated gene transcription. 1α, 25 (OH) 2-20-epi-3-epi-D3 was found to be almost equipotent to 1α, 25 (OH) 2-20-epi-D3 while the metabolites, Y1 and Y2 were found to be less active. The metabolite Y1 when compared to the metabolite Y2