[Effects of diallyl disulfide on differential expression of apoptosis-associated genes in leukemia cell line HL-60]

Diallyl disulfide (DADS) can induce apoptosis in various cancer cell lines in vitro. Leukemia is the most common pediatric malignancy. Recent studies have suggested that DADS can induce apoptosis in human leukemia cells, but its mechanisms remain unclear. This study was to investigate the biological effects of DADS on the apoptosis of human leukemia cell line HL-60, and explore its molecular mechanisms.

After treatment of DADS, cell apoptosis was verified by flow cytometry with Annexin V/PI staining, DNA agarose gel electrophoresis, transmission electron microscopy. The expression profile of apoptosis-associated genes in HL-60 cells, with or without 4-hour treatment of DADS (60 micromol/L), was identified by gene array. The up-regulated Fas-L gene and down-regulated Bag-1 gene were confirmed by reverse transcription-polymerase chain reaction (RT-PCR).

When treated with 15, 30, 60, 120 micromol/L DADS for 24 h, HL-60 cells presented obvious subdiploid peaks. When treated with 60 micromol/L DADS for 4, 8, 12, 24 h, early apoptotic cells were greatly increased. When treated with 60 micromol/L DADS for 24 h, DNA extracted from HL-60 cells displayed a characteristic ladder pattern on agarose gel electrophoresis; typical morphologic apoptotic changes were observed under electron microscope, including cell shrinkage, nuclear condensation, and formation of apoptotic bodies; the differential expression of 8 apoptosis-associated genes were found with gene array. The expression of Fas-L and Bag-1 detected by RT-PCR were consistent with those detected by gene array.

DADS could induce apoptosis in HL-60 cells, which might be mediated by some specific genes and various signal transduction pathways.