Teleocidin, lyngbyatoxin A and their hydrogenated derivatives, possible tumor promoters, induce terminal differentiation in HL-60 cells.

Teleocidin isolated from Streptomyces mediocidicus, its catalytically hydrogenated compound dihydroteleocidin B, and lyngbyatoxin A isolated from marine blue-green alga Lyngbya majuscula as well as its hydrogenated product, tetrahydrolyngbyatoxin A were tested for their ability to induce differentiation of human promyelocytic leukemia cells (HL-60 cells) in culture. All of these indole alkaloids induced differentiation of HL-60 cells, characterized by increased phagocytosis, increased release of lysozyme, and morphological changes resembling macrophages. The concentrations required for the induction were 1-5 ng/ml, showing similarity to those of 12-O-tetradecanoylphorbol-13-acetate (TPA). Teleocidin, lyngbyatoxin A, and tetrahydrolyngbyatoxin A are suggested to be tumor promoters, like TPA and dihydroteleocidin B. The HL-60 cell system might be useful for screening for environmental tumor promoters.