Topoisomerase I-inhibition enhances vitamin D-responsive expression of the receptor for lipopolysaccharide binding protein CD 14.
Pretreatment (4h) of human HL 60 leukemia cells with the topoisomerase I-inhibitor camptothecin (7-28 x 10(-9) Mol/l, single dose) enhanced vitamin D3-responsive CD 14 expression (10(-11)-10(-8) Mol/l vitamin D3) up to twofold, as measured by fluorescence activated flow cytometry after 1-3 days. Camptothecin by itself caused marginal effects. Hybridization of total RNA with oligonucleotides (bases 1358-1333 of CD 14 sequence) showed increased steady state levels of the 1.75 kb CD 14 mRNA after 24 h when normalized to beta-actin. The nuclear accumulation of [3H]-vitamin D3/receptor complexes (VDR) in a nuclear translocation assay was significantly enhanced (by 3 h) in the presence of camptothecin. We conclude that inhibition of topoisomerase I enhances vitamin D3-stimulated CD 14 expression. Topoisomerase I might either be a negatively active transcription factor itself or maintenance of DNA-bending, local supercoiling and accessibility of responsive elements might lead to reduction of VDR turnover and produce a stimulatory effect on vitamin D3-responsive transcription.
Jakob
F
F
Medizinische Poliklinik, University of Würzburg, Germany.
Seufert
J
J
Sarrazin
C
C
Schneider
D
D
Köhrle
J
J
Tony
H P
HP
D000209:Acute-Phase Proteins; D015703:Antigens, CD / Q000096:biosynthesis*; D015214:Antigens, Differentiation, Myelomonocytic / Q000096:biosynthesis*; D002117:Calcitriol / Q000494:pharmacology*; D002166:Camptothecin / Q000494:pharmacology*; D002352:Carrier Proteins / Q000378:metabolism*; D002460:Cell Line; D002467:Cell Nucleus / Q000187:drug effects / Q000378:metabolism; D004305:Dose-Response Relationship, Drug; D005434:Flow Cytometry; D015870:Gene Expression / Q000187:drug effects / Q000502:physiology*; D006801:Humans; D007700:Kinetics; D015473:Leukemia, Promyelocytic, Acute; D018950:Lipopolysaccharide Receptors; D008562:Membrane Glycoproteins; D012333:RNA, Messenger / Q000096:biosynthesis / Q000378:metabolism*; D059004:Topoisomerase I Inhibitors; D014407:Tumor Cells, Cultured; D000099231:Lipopolysaccharide-Binding Protein
D000209:Acute-Phase Proteins; D015703:Antigens, CD; D015214:Antigens, Differentiation, Myelomonocytic; D002117:Calcitriol; D002166:Camptothecin; D002352:Carrier Proteins; D018950:Lipopolysaccharide Receptors; D008562:Membrane Glycoproteins; D012333:RNA, Messenger; D059004:Topoisomerase I Inhibitors; D000099231:Lipopolysaccharide-Binding Protein