| |
|
|
|
|
|
|
|||
|
K Bhalla, J Cole, W MacLaughlin, M Baker, Z Arlin, G Graham and S Grant
We have examined the effect of supraphysiologic concentrations of the
naturally occurring nucleoside deoxycytidine (dCyd) on the in vitro growth
of normal (CFU-GM) and leukemic (L-CFU) myeloid progenitor cells. Bone
marrow samples obtained from 34 consecutive patients undergoing routine
diagnostic bone marrow aspirations for nonmalignant hematologic disorders
exhibited nearly a twofold increment in CFU-GM when continuously cultured
in the presence of 10(-4) mol/L dCyd. Higher dCyd concentrations were
associated with a smaller degree of enhancement of colony formation. In
contrast, the growth of leukemic blast progenitors obtained from patients
with acute nonlymphocytic leukemia were not enhanced by any of the dCyd
concentrations tested. Coadministration of 10(-3) mol/L tetrahydrouridine
(THU), a cytidine deaminase inhibitor, failed to alter the relative
inability of dCyd to enhance L-CFU colony growth. The stimulatory effect of
dCyd on normal CFU-GM was not mediated by the adherent mononuclear cell
population of the marrow, nor was it restricted to the subpopulation of
CFU-GM in S phase at the time of initial exposure. Moreover, treatment of
normal bone marrow cells with dCyd at concentrations ranging from 10(-6) to
5 X 10(-3) mol/L for 24 hours had only a minor effect on the fraction of
CFU-GM in S phase. Coadministration of 10(-4) mol/L dCyd was able to
reverse the inhibitory effects of several putative regulators of normal
myelopoiesis, including leukemia inhibitory activity (LIA), acidic
isoferritins (AIF), and prostaglandin E1 (PGE1). Leukemic myeloblasts
exposed to 10(-4) mol/L dCyd exhibited substantial expansion of
intracellular pools of dCyd triphosphate (dCTP), demonstrating that
inability to metabolize dCyd could not be solely responsible for the
absence of growth potentiation in these cells. These studies suggest that
supraphysiologic concentrations of dCyd may confer a selective in vitro
growth advantage upon normal v leukemic myeloid progenitor cells, and may
free the former from the inhibitory effects of several potential negative
regulators of myelopoiesis.
This article has been cited by other articles:
| |||||||||||
| Copyright © 1986 by American Society of Hematology Online ISSN: 1528-0020 | |||||||||