BRYOSTATIN-5 STIMULATES NORMAL HUMAN HEMATOPOIESIS AND INHIBITS PROLIFERATION OF HL-60 LEUKEMIC-CELLS

In this study we explored the effects of bryostatin-5 on the clonogeni c response of normal bone marrow mononuclear (BM) cells and HL60 myelo id leukemia cells. Leukemic HL60 colony formation was strongly inhibit ed by bryostatin-5 depending on dose and schedule. An inhibitory effec t on HL60 colony formation was readily demonstrated after 1 h of expos ure, reaching a maximal inhibitory effect at 96 h. Normal BM cells dif fered in their clonogenic response: short-term exposure to bryostatin- 5 resulted in increased clonogenicity while longstanding exposure to b ryostatin-5 permitted the survival of a substantial fraction of commit ted progenitors. This differential modulation of normal and leukemic m yeloid clonogenicity by bryostatin-5 suggests a possible role for bryo statin-5 in the treatment of acute myeloid leukemia.