title: Retinoic acid and granulocyte colony-stimulating factor synergistically induce leukocyte alkaline phosphatase in acute promyelocytic leukemia cells.
abstract: In this report we show a strong synergistic interaction between granulocyte colony-stimulating factor (G-CSF) and all-trans retinoic acid (ATRA) on the expression of leukocyte alkaline phosphatase (LAP) in freshly isolated acute promyelocytic leukemia (APL) blasts as well as in NB40 and HL-60 cell lines. The strong synergism observed in these cell types was not evident in two acute leukemia cell lines (K562 and GF-D8), in normal granulocytes, and in monocytes. In freshly isolated leukocytes derived from chronic myelogenous leukemia (CML), in the stable phase of the disease, a weaker interaction between ATRA and G-CSF was documented. The cross-talk between the cytokine and the retinoid was studied in detail in NB4, an immortalized APL leukemia cell line, retaining the 15-17 chromosomal translocation involving the retinoic acid receptor type alpha. The treatment of NB4 cells with G-CSF alone or ATRA alone leads to no increase and to minor induction in LAP activity, respectively. If the cells are treated with the two compounds simultaneously, a dramatic elevation of LAP is observed after 4 days. The synergism between G-CSF and ATRA is evident at concentrations of the retinoid between 10(-7) and 10(-5) mol/L and at concentrations of the cytokine between 1 and 10 ng/mL. The simultaneous presence of the two compounds is necessary to obtain maximal increase of LAP activity and the effect is cell density-dependent. Synergism is specific for G-CSF, and it is not observed with other cytokines and functional inducers of the granulocyte. The augmentation of LAP activity is the consequence of an increased transcriptional rate of the liver/bone/kidney-type (L/B/K-type) alkaline phosphatase gene, as determined by Northern blotting and nuclear run-on analysis using specific cDNA probes. Only one of the two possible alternatively spliced forms of L/B/K-type alkaline phosphatase transcript is detected in NB4 cells after stimulation with G-CSF and ATRA. This mRNA form, which is the one observed in normal polymorphonuclear leukocytes, contains the most upstream leader exon. In NB4 cells, ATRA induces G-CSF, alpha, and beta retinoic acid receptor transcripts, whereas G-CSF has minor effects on the expression of these mRNAs.
authors.affiliation: Unità di Biologia Molecolare, Centro Catullo e Daniela Borgomainerio, Istituto di Ricerche Farmacologiche Mario Negri, Milano, Italy.
authors.forename: M
authors.initials: M
authors.lastname: Gianní
authors.forename: M
authors.initials: M
authors.lastname: Terao
authors.forename: S
authors.initials: S
authors.lastname: Zanotta
authors.forename: T
authors.initials: T
authors.lastname: Barbui
authors.forename: A
authors.initials: A
authors.lastname: Rambaldi
authors.forename: E
authors.initials: E
authors.lastname: Garattini
mesh_terms: D000469:Alkaline Phosphatase / Q000096:biosynthesis* / Q000235:genetics; D015703:Antigens, CD / Q000032:analysis; D015214:Antigens, Differentiation, Myelomonocytic / Q000032:analysis; D001483:Base Sequence; D004357:Drug Synergism; D004790:Enzyme Induction / Q000187:drug effects; D016179:Granulocyte Colony-Stimulating Factor / Q000494:pharmacology*; D006801:Humans; D015473:Leukemia, Promyelocytic, Acute / Q000201:enzymology*; D007962:Leukocytes / Q000201:enzymology*; D016177:Macrophage-1 Antigen / Q000032:analysis; D008969:Molecular Sequence Data; D012333:RNA, Messenger / Q000032:analysis; D016188:Receptors, Granulocyte Colony-Stimulating Factor / Q000235:genetics; D063268:Sialic Acid Binding Ig-like Lectin 3; D014212:Tretinoin / Q000494:pharmacology*; D014407:Tumor Cells, Cultured
chemical_list: D015703:Antigens, CD; D015214:Antigens, Differentiation, Myelomonocytic; C571163:CD33 protein, human; D016177:Macrophage-1 Antigen; D012333:RNA, Messenger; D016188:Receptors, Granulocyte Colony-Stimulating Factor; D063268:Sialic Acid Binding Ig-like Lectin 3; D016179:Granulocyte Colony-Stimulating Factor; D014212:Tretinoin; D000469:Alkaline Phosphatase