Expression of leukocyte alkaline phosphatase gene in normal and leukemic
cells: regulation of the transcript by granulocyte colony- stimulating
factor
A Rambaldi, M Terao, S Bettoni, ML Tini, R Bassan, T Barbui and E Garattini
Istituto di Ricerche Farmacologiche Mario Negri, Milano, Italy.
The levels of leukocyte alkaline phosphatase (LAP) messenger RNA (mRNA) are
evaluated 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 myelogenous leukemia (AML), are devoid of LAP
transcript. These data support the notion that LAP is a marker of the
granulocyte terminal differentiation. 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 lymphocytic 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 the 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.
Volume 76,
Issue 12,
pp. 2565-2571,
12/15/1990
Copyright © 1990 by The American Society of Hematology
