Metabolism of vitamin D in human promyelocytic leukemia cells (HL-60) II. Does the differentiation of the cells alter the metabolism?

The metabolism of 25-hydroxyvitamin D3 (25-OH-D3) in human promyelocytic leukemia cells (HL-60) which had been exposed to 1 alpha, 25-dihydroxyvitamin D3 (1,25-(OH)2D3) was compared with that in untreated cells. 8 alpha, 25-Dihydroxy-9,10-seco-4,6,10(19)-cholestatrien-3-one (8,25-(OH)2-3-oxoneo-D3) was the only major metabolite in untreated HL-60 cells but exposure of the cells to 1,25-(OH)2D3 for 1 day significantly changed the metabolism: 24R,25-dihydroxyvitamin D3 (24R,25-(OH)2D3) was produced as the major metabolite together with 8,25-(OH)2-3-oxoneo-D3 whose production was also increased. The 1,25-(OH)2D3 treatment did not stimulate the production of 25-hydroxyvitamin D3 26,23-lactone by the HL-60 cells. The metabolism of 25-OH-D3 by HL-60 cells was also significantly affected by fetal bovine serum added to the incubation medium: production of 24R,25-(OH)2D3 was significantly reduced and formation of 8,25-(OH)2-3-oxoneo-D3 was completely abolished.