Amsacrine is an
acridine derivative
drug applied in haematological
malignancies. It targets
topoisomerase II enhancing the formation of a cleavable
DNA-
enzyme complex and leading to DNA fragmentation in dividing
cancer cells. Little is known about other modes of the interaction of
amsacrine with
DNA, by which it could affect also normal cells. Using the alkaline comet assay, we showed that
amsacrine at concentrations from the range 0.01 to 10 microM induced DNA damage in normal human lymphocytes, human promyelocytic
leukemia HL-60 cells lacking the p53 gene and murine pro-B lymphoid cells BaF3 expressing BCR/ABL oncogene measured as the increase in percentage tail
DNA. The effect was dose-dependent. Treated cells were able to recover within a 120-min incubation.
Amifostine at 14 mM decreased the level of DNA damage in normal lymphocytes, had no effect on the HL-60 cells and potentiated the
DNA-damaging effect of the
drug in BCR/ABL-transformed cells.
Vitamin C at 10 and 50 microM diminished the extent of DNA damage in normal lymphocytes, but had no effect in
cancer cells. Pre-treatment of the cells with the nitrone spin trap,
N-tert-butyl-alpha-phenylnitrone or
ebselen, which mimics
glutathione peroxidase, reduced the extent of DNA damage evoked by
amsacrine in all types of cells. The cells exposed to
amsacrine and treated with
endonuclease III and
3-methyladenine-DNA glycosylase II, the
enzymes recognizing oxidized and alkylated bases, respectively, displayed greater extent of DNA damage than those not treated with these
enzymes. The results obtained suggest that
free radicals may be involved in the formation of DNA lesions induced by
amsacrine. The
drug can also methylate
DNA bases. Our results indicate that the induction of secondary
malignancies should be taken into account as diverse side effects of
amsacrine.
Amifostine may potentate DNA-damage effect of
amsacrine in
cancer cells and decrease this effect in normal cells and
Vitamin C can be considered as a
protective agent against DNA damage in normal cells.