Detection of in vivo differentiation of murine WEHI-3B D+ leukemia cells transfected with the lac-Z marker gene using two-color flow cytometry

Anti-leukemic activity of Newcastle disease virus strains AF2240 and V4-UPM in murine myelomonocytic leukemia in vivo

Newcastle disease virus (NDV) is a member of the Paramyxoviridae that has caused severe economic losses in poultry industry worldwide. Several strains of NDV were reported to induce cytolysis to cancerous cell lines. It has prompted much interest as anticancer agent because it can replicate up to 10,000 times better in human cancer cells than in most normal cells. In this study, two NDV strains, viserotropic-velogenic strain AF2240 and lentogenic strain V4-UPM, showed cytolytic activity and apoptosis induction against Mouse myelomoncytic leukemia (WEHI 3B). The cytolytic effects of NDV strains were determined using microtetrazolium (MTT) assay. The cytolytic dose - fifty percent (CD(50)) were 2 and 8HAU for AF2240 and V4-UPM strains, respectively. Cells treated with NDV strains showed apoptotic features compared to the untreated cells under fluorescence microscope. NDV induced activation of caspase-3 and DNA laddering in agarose gel electrophoresis which confirmed the apoptosis. The anti-leukemic activity of both strains was evaluated on myelomoncytic leukemia BALB/c mice. The results indicated that both NDV strains significantly decreased liver and spleen weights. It also decreased blasts cell percentage in blood, bone marrow and spleen smears of treated mice (p<0.05). Histopathological studies for spleen and liver confirmed the hematological results of blood and bone marrow. From the results obtained, the exposure to both NDV stains AF2240 and V4-UPM showed similar results for Ara-c. In conclusion NDV strains AF2240 and V4-UPM can affect WEHI 3B leukemia cells in vitro and in vivo.

Sensitive PCR method for the detection and real-time quantification of human cells in xenotransplantation systems

The sensitive detection of human cells in immunodeficient rodents is a prerequisite for the monitoring of micrometastasis of solid tumours, dissemination of leukaemic cells, or engraftment of haematological cells. We developed a universally applicable polymerase chain reaction method for the detection of a human-specific 850-bp fragment of the alpha-satellite DNA on human chromosome 17. The method allows the detection of one human cell in 10(6) murine cells and could be established as both, a conventional DNA polymerase chain reaction-assay for routine screening, and a quantitative real-time polymerase chain reaction-assay using TaqMan-methodology. It was applied to the following xenotransplantation systems in SCID and NOD/SCID mice: (1) In a limiting dilution assay, cells of the MDA-MB 435 breast carcinoma were injected into the mammary fat pad of NOD/SCID mice. It could be shown that 10 cells mouse(-1) were sufficient to induce a positive polymerase chain reaction signal in liver and lung tissue 30 days after transplantation as an indicator for micrometastasis. At this time a palpable tumour was not yet detectable in the mammary fat pad region. (2) Cells of a newly established human acute lymphatic leukaemia were administered intraperitoneally to SCID mice. These cells apparently disseminated and were detectable as early as day 50 in the peripheral blood of living mice, while the leukaemia manifestation was delayed by day 140. (3) In a transplantation experiment using mature human lymphocytes we wanted to standardise conditions for a successful survival of these cells in NOD/SCID mice. It was established that at least 5 x 10(7) cells given intravenously were necessary and that the mice had to be conditioned by 2 Gy body irradiation to get positive polymerase chain reaction bands in several organs. (4) Engraftment studies with blood stem cells originating from cytapheresis samples of tumour patients or from cord blood were undertaken in NOD/SCID mice in order to define conditions of successful engraftment and to use this model for further optimisation strategies. The polymerase chain reaction method presented allowed a reliable prediction of positive engraftment and agreed well with the results of immunohistochemical or FACS analysis. All together, the polymerase chain reaction method developed allows a sensitive and reliable detection of low numbers of human cells in immunodeficient hosts. In combination with real-time (TaqMan) technique it allows an exact quantification of human cells. As this method can be performed with accessible material of living animals, follow up studies for the monitoring of therapeutic interventions are possible in which the survival time of mice as evaluation criteria can be omitted.

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.