The effects and mechanisms of a novel 2-aminosteroid on murine WEHI-3B leukemia cells in vitro and in vivo.

To evaluate the effects of a novel 2-aminosteroid, 2-(4'-methyl-1'-piperazinyl)-3alpha-hydroxyl-5alpha-androstane-17-one (KH), on in vitro murine WEHI-3B leukemia cells, semisolid colony culture, MTT assay, morphological examination, NBT reduction, NSAE test and ACP assay were used to determine proliferation and differentiation. It was found that the growth of leukemia cells in colony and liquid cultures was inhibited by KH (10(-8)-10(-4) mol/l) after treatment for 7 days. The percentages of NBT and NSAE positive cells were 71.17 and 79.25%, respectively, after treatment with KH (10(-8)-10(-6) mol/l) for 5 days. The morphology of treated leukemia cells was identified to be macrophage-like and these cells acquired significant ACP activities. It was indicated that the ACP enzyme activities were increased as high as two and three times of the control, respectively, after treatment with 10(-8) or 10(-5) mol/l KH for 6 days. It was also indicated by DNA fragmentation in gel electrophoresis that WEHI-3B cells were induced toward apoptosis by KH (10(-8)-10(-4) mol/l) when checked at day 5. The c-myc mRNA expressions in WEHI-3B cells were decreased by 58.7% after treatment with KH (10(-8) mol/l) for 5 days. Therefore, it is first reported here that KH, a novel 2-aminosteroid, could suppress proliferation and induce differentiation of WEHI-3B leukemia cells. These differentiated cells were mature macrophage-like cells and showed characteristics of functional phagocytes acquired with acid phosphatase activity. The mechanisms underlying the above effects involved the apoptosis of WEHI-3B leukemia cells and the down-regulation of c-myc oncogene expression. It is also shown that the counts of immature granulocytes and monocytes were significantly decreased in both peripheral blood and bone marrow of BALB/c leukemia mice after KH was administrated per os for 7 consecutive days with four doses (5, 10, 15 or 20 mg/kg day), respectively. It is also observed that the enlarged spleens in leukemia mice were decreased when compared with the control.