PHORBOL ESTER INDUCED OSTEOCLAST-LIKE DIFFERENTIATION OF A NOVEL HUMAN LEUKEMIC-CELL LINE (FLG 29.1)

Studies on human osteoclast formation have been hampered by lack of a defined isolated progenitor cell population. We describe here the establishment of a human leukemic cell line (designated FLG 29.1) from bone marrow of a patient with acute monoblastic leukemia. The cultured cells are predominantly undifferentiated leukemic blasts, but addition of 12-o-tetra-decanoylphorbol 13-acetate (TPA; 0.1-mu-M) induces irreversible differentiation into adherent, non-dividing, multinucleated cells. TPA-treated cells bear surface antigens typical of fetal osteoclasts, degrade Ca-45-labeled devitalized bone particles, display tartrate-resistant acid phosphatase in both mononuclear and multinuclear cells and receptors for calcitonin. Calcitonin increases intracellular cAMP accumulation in TPA-treated cells. TPA-treated cells show some ultrastructural features of osteoclasts as evidenced by transmission EM. These results indicate that FLG 29.1 cells may represent an osteoclast committed cell population, which upon induction with TPA acquire some morphological, phenotypical, and functional features of differentiated osteoclasts.