CC34
Bromodeoxyuridine/DNA Analysis By Flow Cytometry For Proliferation Inhibition And Cell Cycle Regulation By Polyunsaturated Fatty Acids In Human Leukemia HL-60 Cells.
L.C.M. Chiu*, J.M.F. Wan and W.H. Sit, Department of Zoology, University of Hong Kong, Pokfulam Road, Hong Kong.
Bromodeoxyuridine (BrdUrd) labeling DNA and flow cytometry measurement of bivariate BrdUrd/DNA content distributions yield accurate definition of DNA synthesizing S-phase cells as well as proportions of cells in cell cycle phases. We have applied single dose BrdUrd (20 µM) labeling method in vitro to investigate the possible mechanisms responsible for the inhibition of human leukemia HL-60 cells proliferation by long chain polyunsaturated fatty acids (PUFAs). Both arachidonic acid (AA, C20:4
6) and docosahexancoic acid (DHA, C22:63), at the dose of 40 µM incubated for 3 days, induced growth inhibition in the HL-60 cells. The possible oxidative stress damaging effect of PUFAs on the cells was also tested in separate group by adding vitamin E (30 µM) as an antioxidant to the media in the presence and absence of PUFAs. BrdUrd/DNA analysis illustrated that AA induced growth inhibition by arresting cells in the G0/G1 phase while DHA arresting cells in the G2/M phase, and both PUFAs reduced the rate of BrdUrd incorporation into DNA synthesis (labeling Index) by about 7%, respectively. The progression of BrdUrd-labeled S phase cells (relative movement) through the cell cycle was, however, unaffected by either PUFAs. The similar cell cycle kinetics observed in the vitamin E treated groups suggesting that PUFAs mediate growth inhibition in the HL-60 cells is independent of lipid peroxidation products and is due to specific cell cycle effects on the cells.