Sensitivity of fresh acute myeloid leukemia cells to etoposide:
relationship with cell growth characteristics and DNA single-strand breaks
M Chiron, C Demur, V Pierson, JP Jaffrezou, C Muller, S Saivin, C Bordier, C Bousquet, N Dastugue and G Laurent
Laboratoire de Pharmacologie et de Toxicologie Fondamentales, CNRS,
Toulouse, France.
In this study, we evaluated the individual in vitro sensitivity of fresh
acute myeloid leukemia (AML) cells to VP-16, and attempted to correlate
VP-16 cytotoxicity with AML cell growth characteristics and drug-induced
DNA single-strand breaks (SSB). Primary (PE1) colony inhibition assays
allowed us to characterize two distinct groups of AML: group I (patients 1
through 6), which displayed sensitivity to VP- 16 similar to that of normal
CFU-GM (IC90 of 20.52 +/- 2.44 micrograms/mL v 20.48 +/- 2.23 micrograms/mL
after 1 hour drug exposure, respectively); and group II (patients 7 through
11), which was more sensitive to VP-16 (IC90 of 7.26 +/- 2.93
micrograms/mL, P = .004). Subsequently, groups I and II were termed
normosensitive and hypersensitive, respectively. This objective VP-16
sensitivity classification, as determined by PE1, remained unaltered when
assessed by secondary (PE2) colony inhibition assay (evaluating the
self-renewal fraction of AML progenitors), or by cytofluorometric viability
assay (evaluating the ultimately differentiated blast cell population).
These findings would suggest that individual sensitivity to VP-16 of a
particular cell population is maintained throughout CFU-AML
differentiation. Finally, we report that sensitivity of AML cells to VP- 16
did not correlate either with cell growth characteristics or with SSB
generation. Indeed, AML cell sensitivity to VP-16 appeared more closely
related to DNA repair kinetics after drug removal, ie, hypersensitivity
being essentially characterized by a prolonged retention of SSB during the
posttreatment period. Interestingly, the established HL-60 cell line, which
presented greater sensitivity to VP- 16 cytotoxicity than KG1, HEL, and
K562, was also found to exhibit delayed DNA SSB repair kinetics, as
compared with the other AML cell lines. These results suggest that
hypersensitivity to VP-16 of some AML cells may be related to a deficient
DNA-repair mechanism.
Volume 80,
Issue 5,
pp. 1307-1315,
09/01/1992
Copyright © 1992 by The American Society of Hematology