The
leukemia cell line HL60 is widely used in studies of the cell cycle, apoptosis, and adhesion mechanisms in
cancer cells. We conducted a focused cytogenetic study in an HL60 cell line, by analyzing GTG-banded chromosomes before and
after treatment with
pisosterol (at 0.5, 1.0, and 1.8 microg/ml), a
triterpene isolated from Pisolithus tinctorius, a fungus collected in the Northeast of Brazil. Before treatment, 99% of the cells showed the homogeneously staining region (HSR) 8q24 aberration.
After treatment with 1.8 microg/ml
pisosterol, 90% of the analyzed cells lacked this aberration. We further performed a pulse test, in which the cells treated with
pisosterol (0.5, 1.0, and 1.8 microg/ml) were washed and re-incubated in the absence of
pisosterol. Only 30% of the analyzed cells lacked the HSR 8q24 aberration, suggesting that
pisosterol probably blocks the cells with HSRs at interphase. No effects were detected at lower concentrations. At the highest concentration examined (1.8 microg/ml),
pisosterol also inhibited cell growth, but this effect was not observed in the pulse test, reinforcing our hypothesis that, at the concentrations tested,
pisosterol probably does not induce cell death in the HL60 line. The results found for
pisosterol were compared with those for
doxorubicin. Cells that do not show a high degree of gene amplification (HSRs and double-minute chromosomes) have a less aggressive and invasive behavior and are easy targets for
chemotherapy. Therefore, further studies are needed to examine the use of
pisosterol in combination with conventional anti-
cancer therapy.