Regulation of cytokine and growth factor gene expression in human bone
marrow stromal cells transformed with simian virus 40
JL Slack, J Nemunaitis, DF Andrews and JW Singer
Department of Medicine, University of Washington, Seattle.
Marrow stromal cells are thought to regulate hematopoiesis by producing
colony-stimulating factors (CSFs) and other cytokines, either
constitutively or in response to mediators such as interleukin-1 alpha
(IL-1 alpha) or tumor necrosis factor-alpha (TNF alpha). The mechanisms by
which these inflammatory cytokines induce CSF expression in stromal cells
are not fully defined. In this study, we used human marrow stromal cells
transformed by simian virus 40 (SV-MSCs) to study growth factor and
cytokine gene regulation in response to IL-1 alpha and TNF alpha. IL-1
alpha induced significant and prolonged increases in steady- state mRNA
levels for interleukin-6 (IL-6), interleukin-1 beta (IL-1 beta),
granulocyte-macrophage CSF (GM-CSF), and, to a lesser extent,
granulocyte-CSF (G-CSF); this induction was not dependent on new protein
synthesis. Nuclear run-on analyses showed that IL-1 alpha transcriptionally
activated the genes for IL-6, GM-CSF, and IL-1 beta, while TNF alpha
transcriptionally induced expression of IL-6 and IL-1 beta. Furthermore,
mRNA for IL-6 and IL-1 beta was dramatically superinduced by the
combination of cycloheximide and TNF alpha. When SV- MSCs were cultured in
semisolid medium, they formed colonies of blast- like cells that, when
replated on plastic, resumed adherent growth. These "colony-derived" cell
lines, unlike the parental SV-MSCs from which they were derived,
constitutively expressed colony-stimulating activity and mRNA for GM-CSF,
G-CSF, IL-6, and IL-1 beta. In this report, we show that the expression of
IL-6 and IL-1 beta mRNA in the colony-derived cell lines was due, at least
in part, to constitutive transcriptional activation of these genes (similar
to the findings in IL-1 alpha- and/or TNF alpha-stimulated parental
SV-MSCs). However, in contrast to the transcriptional activation of the
GM-CSF gene seen in cytokine-induced parental SV-MSCs, GM-CSF transcripts
accumulated in the colony-derived cell lines by a posttranscriptional
mechanism.
Volume 75,
Issue 12,
pp. 2319-2327,
06/15/1990
Copyright © 1990 by The American Society of Hematology
