Differentiation inducing effects of 2-chloro-3-amino-1,4-naphthoquinone on human leukemia HL-60.

There are some highly cytotoxic anticancer compounds inducing differentiation of cancer cells to normal cells at below highly cytotoxic concentration. Naphthoquinone derivatives having cytotoxic effects on cancer cell were tested to learn whether they have differentiation inducing activity in human leukemia HL-60 cells or not. When HL-60 cells were treated with 2-chloro-3-amino-1,4-naphthoquinone (CANQ) for four days, differentiation-related phenotypes such as nitrobluetetrazolium (NBT)-reducing ability and phagocytosis were induced. These differentiation markers were increased by cotreatment with 1,25-dihydroxyvitamin D3 which is a well-known inducer of differentiation in HL-60 cells. To evaluate the route of differentiation induced by CANQ, we examined naphthol AS-D chloroacetate esterase and alpha-naphthylacetate esterase activities and changes in cellular size and granulation. Treatment of HL-60 cells with CANQ for four days resulted in an 82.4% increase in alpha-naphthylacetate esterase activity in spite of a 0.2% increase in naphthol AS-D chloroacetate esterase activity. The size of cells in cell mass was larger and granulation was more decreased than untreated cells. These results indicate that HL-60 cells were induced to differentiate into macrophage-like cells.