title: Effects of uremic serum on 1,25-dihydroxyvitamin D3-induced differentiation of a human promyelocytic leukemia cell line, HL-60.
abstract: 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.
authors.affiliation: Second Department of Internal Medicine, Osaka City University Medical School, Japan.
authors.forename: M
authors.initials: M
authors.lastname: Inaba
authors.forename: S
authors.initials: S
authors.lastname: Okuno
authors.forename: H
authors.initials: H
authors.lastname: Koyama
authors.forename: Y
authors.initials: Y
authors.lastname: Nishizawa
authors.forename: H
authors.initials: H
authors.lastname: Morii
mesh_terms: D000328:Adult; D000368:Aged; D002117:Calcitriol / Q000494:pharmacology*; D002454:Cell Differentiation / Q000187:drug effects*; D000242:Cyclic AMP / Q000378:metabolism; D005260:Female; D006801:Humans; D015473:Leukemia, Promyelocytic, Acute / Q000473:pathology*; D008297:Male; D018167:Receptors, Calcitriol; D011987:Receptors, Steroid / Q000032:analysis; D014407:Tumor Cells, Cultured; D014511:Uremia / Q000097:blood*
chemical_list: D018167:Receptors, Calcitriol; D011987:Receptors, Steroid; D000242:Cyclic AMP; D002117:Calcitriol