Effects of concurrent use of rh-IFN-gamma and curcumin on the anti-proliferative capacity of HL-60 cells.

To understand the effect of rh-IFN-gamma on the ability of curcumin to kill HL-60 cells in vitro, the myeloid leukemic cell line HL-60 was studied by using cell culture. BrdU incorporation rate was examined by SABC, DNA content was determined by flow cytometry and apoptotic cell percentage was determined by TUNEL method. The results showed that curcumin inhibited proliferation of leukemic cells in a dose-dependent manner. When HL-60 cells were treated with 25 mumol curcumin for 24 h, the proliferative inhibitory rate was 43.75 +/- 2.00%. This effect could be enhanced obviously by IFN-gamma, the combined proliferative inhibitory rate increased to over 80%. The 5-BrdU incorporation rate and the distribution of DNA content indicated that curcumin could arrest cells in the G1/G0 and G2/M phase of cell cycle. At the same time, the sub-G1 peak (apoptotic peak) appeared. After IFN-gamma combined with curcumin, DNA synthesis rate decreased further. It showed a significant difference when compared with single drug group (P < 0.05). Meanwhile, sub-G1 peak also increased. The percentage of TUNEL positive cells was aslo increased. It is concluded that IFN-gamma can enhance the antiproliferative ability of curcumin against HL-60 cells.