Effects of calcitriol on nuclear transcription during human HL-60 promyelocytic leukemia cell differentiation.
An HL-60 in vitro transcription assay was developed and used to monitor HL-60 human promyelocytic leukemia cell transcription during calcitriol-induced monocytic differentiation. Treatment of cells with calcitriol (50 nM) for 96 h produced a 48% reduction in total DNA-dependent RNA polymerase activity with a corresponding reduction in alpha-amanitin-sensitive (RNA polymerase II) activity. Nuclei isolated from cells treated with the less efficacious vitamin D analogues, 24,25-dihydroxyvitamin D3, and 1 alpha-hydroxyvitamin D3, did not exhibit nuclear transcription that was significantly different from control nuclei. Transcription in nuclei isolated from calcitriol-treated cells was decreased by 40 to 50% concomitant with monocytic differentiation, as assayed by acquisition of nitroblue tetrazolium reducing activity. Maximal decrease in transcription was achieved by 45 h postinduction, whereas expression of nitroblue tetrazolium reducing activity peaked at approximately 70 h, and decreased DNA synthesis was evident by 48 h. These observations suggest that calcitriol induction of HL-60 differentiation results in monocytes with reduced requirements for gene transcription and that transcription changes accompany expression of nitroblue tetrazolium reducing activity.
Bresnick
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Simpson
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D002117:Calcitriol / Q000494:pharmacology / Q000502:physiology*; D002454:Cell Differentiation; D002460:Cell Line; D002467:Cell Nucleus / Q000378:metabolism*; D004247:DNA / Q000096:biosynthesis; D012321:DNA-Directed RNA Polymerases / Q000032:analysis; D006801:Humans; D015470:Leukemia, Myeloid, Acute / Q000378:metabolism / Q000473:pathology*; D009580:Nitroblue Tetrazolium / Q000378:metabolism; D014158:Transcription, Genetic / Q000187:drug effects*
D009580:Nitroblue Tetrazolium; D004247:DNA; D012321:DNA-Directed RNA Polymerases; D002117:Calcitriol