EFFECTS OF BRYOSTATIN-5 AND HEMATOPOIETIC GROWTH-FACTORS ON ACUTE MYELOID-LEUKEMIA CELL-DIFFERENTIATION, PROLIFERATION, AND PRIMARY PLATINGEFFICIENCY

We examined the effect of bryostatin-5 (bryo-5) with and without a com bination of myeloid growth promoting factors on human acute myeloid le ukemia (AML) cell growth, maturation, and primary plating efficiency. In vitro treatment of AML samples with bryo-5 induced a macrophage-lik e cell differentiation as evidenced by morphological changes, esterase staining, and cell surface expression of CD11a and CD18. AML cells ex posed to growth factors doubled their cell numbers following culture, this increase being abrogated by co-exposure to bryo-5. An antiprolife rative effect, as well as the antagonistic interaction of bryo-5 with growth factors, was confirmed in methylcellulose clonogenic assays. To gether, these findings indicate that the compound bryo-5 exerts an ant i-proliferative effect on AML cells and counteracts growth factor indu ced leukemic proliferation.