RHAMNAZIN INHIBITS PROLIFERATION AND INDUCES APOPTOSIS OF HUMAN JURKAT LEUKEMIA CELLS IN VITRO.

Antiproliferative and apoptogenic effects of rhamnazin, a dimethoxylated derivative of quercetin, were studied in human acute lymphoblastic leukemia Jurkat cells. The cytotoxicity and apoptogenic activity of rhamnazin in vitro are inferior to that of quercetin. The apoptogenic activity of rhamnazin is realized via mitochondrial pathway and associated with activation of caspase-9 and -3. The additive apoptogenic effect of rhamnazin and suboptimal doses of etoposide, a DNA topoisomerase II inhibitor, is demonstrated. Therefore, methylation of quercetin modifies its biological effects considerably.

[Comparative effects of flavonoids on cell cycle passage and apoptosis induction in human acute lymphoblastic leukemia MT-4 cells].

In the present study, 8 flavonoids of three major flavonoid subgroups, namely flavones, flavonols and flavanones were tested for their cytotoxic and apoptogenic effects in human acute lymphoblastic leukemia MT-4 cells in vitro. Apoptotic cells were identified by DNA flow cytometric analysis. The effects of the flavonoids on the cell cycle patterns and activation of caspase-3 were also examined. Among the flavonoids tested, 7,8-benzoflavone, flavone, quercetin, chrysin, and galangine were shown to be effective apoptosis inducers. At concentrations corresponding to ED50, the flavonoids mentioned above exerted varying degrees of caspase-3 activation in MT-4 cells. The flavonoid-treated cells demonstrated different cell cycle profiles with accumulation in either G0/G1 (flavone, morin) or G2/M (7,8-benzoflavone, naringenin, quercetin, apigenin) phase. The induction of apoptosis did not correlate with phase-specific effects of flavonoid assayed. The relationship between chemical structure and apoptogenic activity of flavonoids tested is discussed.

Study of morphocytochemical and immunophenotypic features of acute leukemia stem cells.

The immunophenotypic profile of hematopoietic stem cells (HSC) and hematopoietic precursor cells as well as leukemic stem cells (LSC) has been extensively studied in several laboratories worldwide. The results of our studies suggest that the standard panel for classification of acute leukemias should be supplemented with several new markers allowing us to identify more precisely the different forms of the leukemias being of the closely related origin, for example AML M6b and AML M7. The common bipotent LSC in AML M7 of low grade and AML M6b may exist analogous to precursor cell common for megakaryocytopoiesis and erythropoiesis. We have also found the similarity between blast cells in pro-B-ALL [t (4;11), 11q23] and AML M5a [t (9;11), 11q23]. Such similarity of immunophenotype and cytogenetic abnormalities in blast cells in pro-B-ALL and AML M5a may be considered as hint explaining the cases of AML M5a as a recurrence of leukemia in children with originally diagnosed pro-B-ALL.

[Modified alkaloids from Chelidonium majus L. induce G2/M arrest, caspase-3 activation, and apoptosis in human acute lymphoblastic leukemia MT-4 cells].

The novel anticancer drug amitosine representing the mixture of thiophosphamide-modified alkaloids from Chelidonium majus L. has been reported to inhibit growth of various solid tumors in vivo. However, its antileukemic activity as well as the mechanisms of anticancer action have not been yet extensively examined. In this study, amitosine treatment at a dose of 100-250 microg/mL for 24 h resulted in dose-dependent inhibition of MT-4 cell proliferation in vitro with apoptosis induction in the setting of the significant G2/M phase arrest (up to 70% of cells). While amitosine induced caspase-3 activation in MT-4 cells, the increase in the number of cells containing the active caspase-3 did not correlate with the increase of apoptotic cell percentage. Western blotting data revealed the accumulation of cytochrome c in cytosolic fraction of MT-4 cells within 6 h after treatment with 100 microg/mL amitosine. To sum up, amitosine has been shown to possess strong antiproliferative and apoptosis-inducing activities in MT-4 cells in vitro, which seem to be mediated partially through caspase-dependent mitochondrial death pathways.

[The production of HIV recombinant proteins and their immunochemical characteristics]. / Oderzhannia rekombinatnykh bilkiv VIL ta ïkh imunokhimichna kharakterystyka.

Several Escherichia coli strains producing HIV-specific recombinant proteins including env-1, env-2, and gag sequences have been obtained using different gene engineering techniques. These proteins have been isolated and purified from bacterial lysates by ion exchange chromatography on DEAE-Toyopearl and Streamline-SP columns. Polyacrylamide gel electrophoresis and immunoblotting have been used to prove recombinant proteins purity and to identify them. These proteins have been shown to be adequate as antigen preparations for enzyme immunoassay test-systems aimed at anti-HIV antibodies detection.