Enhancement of 1,25-dihydroxyvitamin D3- and all-trans retinoic acid-induced differentiation of human leukemia HL-60 cells by Phyllostachys nigra var. henonis

Human myeloid leukemia HL-60 cells are differentiated into monocytic or granulocytic lineage when treated with 1,25-dihydroxyvitamin D3 [1,25-(OH)2D3] or all-trans retinoic acid (RA), respectively. In this study, the effect of acetone fraction prepared from bamboo leaf on cell differentiation was investigated in a HL-60 cell culture system. Treatment of HL-60 cells with 50-400 μg/ml acetone fraction of bamboo leaf for 72 hr inhibited cell proliferation and induced a little increase in cell differentiation, as demonstrated by the MTT and nitroblue tetrazolium reduction assay. Interestingly, synergistic induction of HL-60 cell differentiation was observed when the acetone fraction of bamboo leaf was combined with either 5 nM 1,25-(OH)2D3 or 50 nM all-trans RA. Flow cytometric analysis indicated that combinations of 1,25-(OH)2D3 and the acetone fraction of bamboo leaf stimulated differentiation predominantly to monocytes, whereas combinations of all-trans RA and the acetone fraction of bamboo leaf stimulated differentiation predominantly to granulocytes. These results suggest that the acetone fraction of bamboo leaf enhanced leukemia cell differentiation and suggest a possibility of bamboo in the treatment of leukemia.