Suberoylanilide hydroxamic acid (SAHA) at subtoxic concentrations increases the adhesivity of human leukemic cells to fibronectin.

Suberoylanilide hydroxamic acid (SAHA) is an inhibitor of histone deacetylases (HDACs) which is being introduced into clinic for the treatment of hematological diseases. We studied the effect of this compound on six human hematopoietic cell lines (JURL-MK1, K562, CML-T1, Karpas-299, HL-60, and ML-2) as well as on normal human lymphocytes and on leukemic primary cells. SAHA induced dose-dependent and cell type-dependent cell death which displayed apoptotic features (caspase-3 activation and apoptotic DNA fragmentation) in most cell types including the normal lymphocytes.

Isoform-specific cleavage of 14-3-3 proteins in apoptotic JURL-MK1 cells.

The proteins of 14-3-3 family are substantially involved in the regulation of many biological processes including the apoptosis. We studied the changes in the expression of five 14-3-3 isoforms (beta, gamma, epsilon, tau, and zeta) during the apoptosis of JURL-MK1 and K562 cells. The expression level of all these proteins markedly decreased in relation with the apoptosis progression and all isoforms underwent truncation, which probably corresponds to the removal of several C-terminal amino acids.

Rho-signaling pathways in chronic myelogenous leukemia.

Chronic myelogenous leukemia (CML) is a hematological malignancy that is characteristic by as expansion of myeloid cells and their premature release into the circulation. The molecular cause of CML is the fusion oncoprotein Bcr-Abl whose constitutive tyrosine-kinase (TK) activity maintains enhanced signaling through multiple signal transduction pathways and confers proliferative and survival advantage to CML cells. These effects can be largely suppressed by TK inhibitor Imatinib mesylate, currently the leading drug in CML treatment.

Labeling of apoptotic JURL-MK1 cells by fluorescent caspase-3 inhibitor FAM-DEVD-fmk occurs mainly at site(s) different from caspase-3 active site.

Background: Fluorochrome-labeled inhibitors of caspases (FLICA) have been designed as an alternative tool for the detection of caspase activation in whole cells. They should label the active site of the corresponding caspase through a covalent attachment to the reactive cysteine residue.

Methods: One of the FLICAs, FAM-DEVD-fmk, was used to monitor apoptosis progression in leukemic JURL-MK1 cells by means of flow cytometry.

The proteomic study of sodium butyrate antiproliferative/cytodifferentiation effects on K562 cells.

Employing methods of cell biology and proteome analysis tools, we examined effects of an inhibitor of histone deacetylases, sodium butyrate (SB), on the proliferation/differentiation characteristics of chronic myelogenous leukemia (CML)-derived cells K562. SB suppressed proliferation of K562 cells by inducing cell cycle arrest in G1 phase, which was followed by their transition to G0 phase (decrease of Ki-67 antigen-positive cells) and erythroid differentiation (increased glycophorin A expression and synthesis of hemoglobins). Neither terminal apoptosis (low counts of TUNEL-positive cells) nor necrosis (moderate counts of propidium iodide-positive cells) occurred.

Photodynamic treatment (ALA-PDT) suppresses the expression of the oncogenic Bcr-Abl kinase and affects the cytoskeleton organization in K562 cells.

K562 is the chronic myelogenous leukemia (CML)-derived cell line that expresses high levels of chimeric oncoprotein Bcr-Abl. The deregulated (permanent) kinase activity of Bcr-Abl leads to continuous proliferation of K562 cells and their resistance to the apoptosis promotion by conventional drugs. The photodynamic treatment (PDT) based on the application of 5-aminolevulinic acid (ALA) and irradiation with blue light (ALA-PDT) resulted in the suppression of K562 cells proliferation.

To the intranucleolar translocation of AgNORs in leukemic early granulocytic and plasmacytic precursors.

Early leukemic granulocytic and plasmacytic precursors were studied in vitro and in vivo to provide an information on the intranucleolar distribution of AgNORs (silver stained nucleolus organizer regions). In most of these cells AgNORs appeared as clusters of silver stained particles distributed in the whole nucleolar body. On the other hand, in some leukemic early granulocytic precursors, i.

Fast apoptosis and erythroid differentiation induced by imatinib mesylate in JURL-MK1 cells.

We compare the effects of Imatinib mesylate (Glivec) on chronic myeloid leukemia derived cell lines K562 and JURL-MK1. In both cell lines, the cell cycle arrests in G(1)/G(0) phase within 24 h after the addition of 1 microM Imatinib. This is followed by a decrease of Ki-67 expression and the induction of apoptosis.

The effect of 5-aminolevulinic acid-based photodynamic treatment (PDT) on nucleoli of leukemic granulocytic precursors represented by K562 blastic cells in vitro.

Background: Since photodynamic treatment (PDT) induces apoptosis in individual HL-60 cells originating from early granulocytic precursors of acute myeloid leukemia, the present study was undertaken to provide information on such treatment of K562 cells, which originate from early granulocytic precursors of chronic myeloid leukemia (blastic phase) and carry the bcr/abl fusion gene with anti-apoptotic properties.

Material/methods: PDT was based on the 5-aminolevulinic acid treatment of K562 cells, followed by blue light irradiation under conditions which in HL-60 cells induce an apoptotic process without previous terminal maturation. Nuclei and nucleoli were visualized by cytochemical procedures to demonstrate DNA, RNA and silver stained proteins of nucleolus organizer regions (AgNORs).

A short note on the nucleolar size and density in apoptotic leukemic granulocytic precursors (HL-60 cells).

The present study was undertaken to provide more information on the nucleolar size and density in mononuclear blastic granulocytic precursors represented by HL-60 cells the proliferation of which was blocked by photodynamic treatment (PDT) which induced apoptotic process without preceding terminal maturation. Both the nucleolar size and density did not change in apoptotic cells in comparison with controls. Thus, large and dense nucleoli in apoptotic cells are not necessarily related to the nucleolar biosynthetic or cell proliferation activity.

Interferon-alpha suppresses proliferation of chronic myelogenous leukemia cells K562 by extending cell cycle S-phase without inducing apoptosis.

We examined the effects of interferon-alpha (IFN-alpha) treatment on the growth, cell cycle, proliferation, and apoptotic parameters as well as adhesive properties and proteome of chronic myelogenous leukemia (CML)-derived K562 cells. IFN-alpha treatment (200 to 600 U/ml, 24 to 72 h) suppressed growth and caused accumulation of K562 cells in the S-phase of cell cycle (increase in S-phase cells by up to 52% in comparison with the untreated controls) at the expenses of cells in G1-phase. No transition of cells to G0-phase occurred as followed from Ki-67 protein determination.

Mitochondrial and endoplasmic reticulum stress-induced apoptotic pathways are activated by 5-aminolevulinic acid-based photodynamic therapy in HL60 leukemia cells.

We studied the mechanism of the cytotoxic effects of 5-aminolevulinic acid-based photodynamic therapy (ALA-PDT; induction with 1 mM ALA for 4 h followed by a blue light dose of 18 J/cm(2)) on the human promyelocytic leukemia cell line HL60 using biochemical and electron microscopy methods. The disruption of mitochondrial membrane potential, deltapsi(m), was paralleled by a decrease in ATP level, unmasking of the mitochondrial antigen 7A6, release of cytochrome c into the cytoplasm, activation of caspases 9 and 3 and cleavage of poly(ADP-ribose) polymerase (PARP). This was followed by DNA fragmentation.

Nucleolar asynchrony observed in HL-60 leukemic granulocytic precursors resistant to 5-aminolaevulinic acid-based photodynamic treatment.

To provide more information on the 5-aminolaevulinic acid (ALA)-induced photodynamic effect on nucleoli, morphologically expressed nucleolar asynchrony (the presence of 'active' large nucleoli with an uniform distribution of RNA and 'resting' ring-shaped nucleoli in one and the same nucleus) was studied in cultured HL-60 leukemic granulocytic precursors using a simple cytochemical procedure for the demonstration of RNA. Nucleolar asynchrony was mainly expressed in cells which were apparently resistant to ALA-based photodynamic treatment (PDT) since most of them (about 75%) exhibited this phenomenon.