James S Y, Turner A, Colston K W
a Divisions of Gastroenterology, Endocrinology and Metabolism.
b Medical Oncology , St. George's Hospital Medical School , London , SW17 ORE.
Hematology. 1997;2(4):289-301. doi: 10.1080/10245332.1997.11746348.
The ability of 1,25-dihydroxyvitamin D3 and two of its analogues, EB1089 and KH1060 to induce apoptosis in two leukaemia cell lines, HL-60 and U937 were examined. In addition, the effects of the retinoid 9-cis retinoic acid (9-cis RA) were assessed alone or in combination with the vitamin D compounds. In both the HL-60 and U937 cell lines none of the vitamin D derivatives alone were capable of inducing apoptosis, as assessed by flow cytometry and cell death ELISA techniques. In contrast, 9-cis RA induced apoptosis in HL-60 but not U937 cells. Co-treatment of HL-60 cells with the vitamin D compounds and 9-cis RA resulted in an enhanced induction of apoptosis, which was not observed with U937 cell co-treatment. Western analysis of bcl-2 and bax protein levels revealed that combinations of the vitamin D and retinoid compounds decreased bcl-2 in HL-60 but not U937 cells, suggesting a change in the bcl-2/bax heterodimeric ratio in the former which would favour apoptosis. Further Western analyses were performed to examine the regulation of vitamin D receptor (VDR), retinoid X receptor (RXR) and retinoic acid receptor (RAR) following single or co-treatment with their respective ligands. Studies revealed that 9-cis RA alone down-regulated RXR, and diminished VDR and RAR protein levels in the presence of the vitamin D compounds in both cell lines. However, in HL-60 cells the vitamin D derivatives were capable of preventing the further down-regulation of RXR in the presence of the retinoid. These results demonstrate cell specific responses to the induction of apoptosis and regulation of apoptosis related gene products by vitamin D and retinoid compounds, highlighting complex signalling interactions between their receptors.
研究了1,25 - 二羟基维生素D3及其两种类似物EB1089和KH1060在两种白血病细胞系HL - 60和U937中诱导细胞凋亡的能力。此外，还评估了视黄酸9 - 顺式维甲酸（9 - cis RA）单独或与维生素D化合物联合使用的效果。通过流式细胞术和细胞死亡ELISA技术评估发现，在HL - 60和U937细胞系中，单独使用任何一种维生素D衍生物均不能诱导细胞凋亡。相反，9 - cis RA可诱导HL - 60细胞凋亡，但不能诱导U937细胞凋亡。维生素D化合物与9 - cis RA共同处理HL - 60细胞可增强细胞凋亡的诱导，而U937细胞共同处理时未观察到这种增强作用。对bcl - 2和bax蛋白水平的western分析表明，维生素D和视黄酸化合物的组合可降低HL - 60细胞中的bcl - 2水平，但不能降低U937细胞中的bcl - 2水平，这表明前者中bcl - 2/bax异二聚体比例发生变化，有利于细胞凋亡。进一步进行western分析以检测在单独或共同使用各自配体处理后维生素D受体（VDR）、视黄酸X受体（RXR）和视黄酸受体（RAR）的调节情况。研究发现，单独使用9 - cis RA可下调RXR，并在两种细胞系中维生素D化合物存在的情况下降低VDR和RAR蛋白水平。然而，在HL - 60细胞中，维生素D衍生物能够在视黄酸存在的情况下阻止RXR的进一步下调。这些结果证明了细胞对维生素D和视黄酸化合物诱导细胞凋亡及调节凋亡相关基因产物的特异性反应，突出了它们受体之间复杂的信号相互作用。
