Paradoxical anti-leukemic effects of plant-derived tumor promoters on a human thymic lymphoblast cell line.

Three different diterpen polyols and the teleocidin have antileukemic effects on the human thymic leukemia cell line HPB-ALL by inducing phenotypic differentiation. We tested TPA (phorbol esters), mezerein (daphnane), milliamin (ingenol ester) and teleocidin B (teleocidins) as representative of the chemical structure of each principle and found that these agents have the similar biological activity of inducing phenotypic differentiation in HPB-ALL cells. Moreover, competitive binding of [3H]PDB to cell-surface receptors was significantly inhibited by these agents; n-butyrate and phorbol per se did not inhibit the binding of [3H]PDB. Despite differences in the structure of the principles, these agents may have similarly acting side-chain structures.