Inaba M, Okuno S, Koyama H, Nishizawa Y, Morii H
Second Department of Internal Medicine, Osaka City University Medical School, Japan.
J Nutr Sci Vitaminol (Tokyo). 1991 Dec;37 Suppl:S93-103. doi: 10.3177/jnsv.37.supplement_s93.
The mechanism by which resistance to 1,25 dihydroxyvitamin D3 (1,25-(OH)2D3) occurs in patients with chronic renal failure was studied. This agent induces differentiation and 1,25-(OH)2D3-24-hydroxylase activity in the mitochondria of the human promyelocytic leukemia cell line, HL-60, via a steroid-hormone receptor mechanism. HL-60 cells were cultured in RPMI 1640 medium supplemented with 10% normal or uremic serum. Treatment of these cells with 10(-8)M 1,25-(OH)2D3 for 5 days in a medium containing 10% uremic serum from 4 patients with chronic renal failure resulted in a maturation of the cells amounting to 30.3 +/- 18.7% (mean +/- SD) and 32.5 +/- 11.2%, as obtained by NBT reduction assay and NSE assay, respectively. These values were significantly lower than those obtained with 10% serum from 3 normal controls (66.6 +/- 12.8%, 58.3 +/- 10.9%, p less than 0.02). The treatment of HL-60 cells with 1,25-(OH)2D3 in a mixture of 5% normal plus 5% uremic serum caused cell differentiation to an extent similar to that in 10% uremic serum, which suggests the presence of a substance(s) having 1,25-(OH)2D3-inhibitory activity in the uremic serum. Exposure of HL-60 cells to uremic serum significantly impaired their responsiveness to 1,25-(OH)2D3 as assessed by the induction of the cell's ability to hydroxylate the C-24 position of 1,25-(OH)2[3H]D3. The mechanism by which uremic serum confers an impaired cellular response to 1,25-(OH)2D3 seemed to be due, in part, to a decrease in 1,25-(OH)2D3 receptor levels. A significant positive correlation was observed between intracellular cAMP levels and 1,25-(OH)2D3-induced HL-60 cell maturation. In summary, the mechanism by which uremic serum confers 1,25-(OH)2D3 resistance upon HL-60 cells seemed to be due to the presence of 1,25-(OH)2D3-inhibitory activity in uremic serum, which may modulate cellular responsiveness to 1,25-(OH)2D3 by such mechanisms as reducing 1,25-(OH)2D3 receptor levels in the cells, in part through alteration in cAMP metabolism.
对慢性肾衰竭患者中出现的对1,25 - 二羟基维生素D3（1,25-(OH)2D3）耐药的机制进行了研究。该药物通过类固醇激素受体机制诱导人早幼粒细胞白血病细胞系HL - 60线粒体中的分化及1,25-(OH)2D3 - 24 - 羟化酶活性。HL - 60细胞在补充有10%正常或尿毒症血清的RPMI 1640培养基中培养。在含有来自4例慢性肾衰竭患者的10%尿毒症血清的培养基中，用10(-8)M 1,25-(OH)2D3处理这些细胞5天，通过NBT还原试验和NSE试验分别得到细胞成熟率为30.3±18.7%（平均值±标准差）和32.5±11.2%。这些值显著低于来自3名正常对照的10%血清所得到的值（66.6±12.8%，58.3±10.9%，p<0.02）。在5%正常血清加5%尿毒症血清的混合物中用1,25-(OH)2D3处理HL - 60细胞导致细胞分化程度与在10%尿毒症血清中相似，这表明尿毒症血清中存在具有1,25-(OH)D3抑制活性的物质。通过诱导细胞对1,25-(OH)2[3H]D3的C - 24位羟化能力来评估，将HL - 60细胞暴露于尿毒症血清会显著损害其对1,25-(OH)2D3的反应性。尿毒症血清导致细胞对1,25-(OH)2D3反应受损的机制似乎部分是由于1,25-(OH)2D3受体水平降低。观察到细胞内cAMP水平与1,25-(OH)2D3诱导的HL - 60细胞成熟之间存在显著正相关。总之，尿毒症血清赋予HL - 60细胞对1,25-(OH)2D3耐药的机制似乎是由于尿毒症血清中存在1,25-(OH)2D3抑制活性，其可能通过降低细胞内1,25-(OH)2D3受体水平等机制来调节细胞对1,25-(OH)2D3的反应性，并部分通过cAMP代谢的改变来实现。
