EXPRESSION OF LEUKOCYTE ALKALINE-PHOSPHATASE GENE IN NORMAL AND LEUKEMIC-CELLS - REGULATION OF THE TRANSCRIPT BY GRANULOCYTE COLONY-STIMULATING FACTOR

  • 15 December 1990
    • journal article
    • research article
    • Vol. 76  (12) , 2565-2571
Abstract
The levels of leukocyte alkaline phosphate (LAP) messenger RNA (mRNA) are evaluatd in B and T lymphocytes, monocytes, and polymorphonuclear cells (PMNs), and this transcript is found to be present only in PMNs. Precursors of the myelomonocytic pathway, represented by leukemic cells isolated from several cases of chronic myelogenous leukemia (CML) in its stable and blastic phase and acute myelogenus leukemia (AML), are devoid of LAP transcript. These data support the notion that LAP is a marker of the granulocyte terminal differentation. Despite the absence of LAP mRNA in both the myeloid and the lymphoid precursors, nuclear run-on experiments show constitutive transcription of the LAP gene in leukemic cells obtained from AML, CML, as well as acute lymphoblastic leukemia (ALL) and B-cell chronic lymphocyte leukemia (B-CLL). In CML and in chronic myelo-monocytic leukemia (CMML) PMNs, granulocyte colony-stimulating factor (G-CSF) specifically accumulates LAP mRNA without showing a substantial increase in the rate of transcription of LAP gene. Once increased by G-CSF, LAP mRNA is very stable, showing a half-life of more than 4 hours in the presence of actinomycin-D. G-CSF is suggested to play a pivotal role in the modulation of LAP transcript in PMNs.