In vitro response of human pathological hematopoietic cells to fludarabine phosphate

The present study was undertaken to determine a possible influence of fludarabine (fludarabine phosphate, F-ara-AMP) on the cell viability and count. The experiments were performed in vitro on human acute lymphoblastic MOLT-4 cells, human acute myeloblastic ML-1 cells, and human histiocytic lymphoma U-937 cells. The research was conducted using the spectrophotometric and Beckman Coulter methods. The cell viability was analyzed using MTT assay. The cell count was detected using an electronic Z2 Coulter counter. Temporary changes in the cell viability and count were assessed at 24h and 48h after F-ara-AMP application. The in vitro activity of fludarabine phosphate against MOLT-4, ML-1, and U-937 cells was compared. F-ara-AMP applied at the four concentrations - 250 nM, 500 nM, 750 nM, and 1 μM - distinctly decreased the viability and count of the pathological hematopoietic cells. The effects of F-ara-AMP on MOLT-4, ML-1, and U-937 cells were dependent on the tested agent and its dose, the time intervals after the agent application, and the cell line used. ML-1 and U-937 cells appeared to be more resistant than MOLT-4 cells to the action of fludarabine phosphate. The in vitro response of the three human pathological hematopoietic cell lines to the F-ara-AMP action, was shown

Characterization of the monocyte-specific esterase (MSE) gene

Carboxylic esterases are widely distributed in hematopoietic cells. Monocytes express the esterase isoenzyme (termed 'monocyte-specific esterase', MSE) that can be inhibited by NaF in the alpha-naphthyl acetate cytochemical staining. We examined the expression of MSE in normal cells and primary and cultured leukemia-lymphoma cells. The MSE protein was demonstrated by isoelectric focusing (IEF); MSE mRNA expression was investigated by Northern blotting and reverse transcriptase-polymerase chain reaction (RT-PCR). The following samples were positive for MSE protein and Northern mRNA expression: 20/24 monocytic, 4/32 myeloid, and 1/20 erythroid-megakaryocytic leukemia cell lines, but none of the 112 lymphoid leukemia or lymphoma cell lines; of the normal purified cell populations only the monocytes were positive whereas, T, B cells, and granulocytes were negative; of primary acute (myelo) monocytic leukemia cells (CD14-positive, FAB M4/M5 morphology) 14/20 were Northern mRNA and 11/14 IEF protein positive. RT-PCR revealed MSE expression in 29/49 Northern-negative lymphoid leukemia-lymphoma cell lines. The RT-PCR signals in monocytic cell lines were on average 50-fold stronger than the mostly weak trace expression in lymphoid specimens. On treatment with various biomodulators, only all-trans retinoic acid significantly upregulated MSE message and protein levels but could not induce new MSE expression in several leukemia cell lines; lipopolysaccharide and interferon-gamma increased MSE expression in normal monocytes. Analysis of DNA methylation with sensitive restriction enzymes showed no apparent regulation of gene expression by differential methylation; the MSE gene is evolutionarily conserved among mammalian species; the half-life of the human MSE transcripts was about 5-6 h. The extent of MSE expression varied greatly among different monocytic leukemia samples. However, the MSE overexpression in a significant number of specimens was not associated with gene amplification, gross structural rearrangements or point mutations within the cDNA region. Taken together, the results suggest that MSE expression is not absolutely specific for, but strongly associated with cells of the monocytic lineage; MSE is either not expressed at all or expressed at much lower levels in cells from other lineages. The biological significance, if any, of rare MSE messages in lymphoid cells detectable only by the hypersensitive RT-PCR remains unclear. Further studies on the regulation of this gene and on the physiological function of the enzyme will no doubt be informative with respect to its striking overexpression in some malignant cells and to a possible role in the pathobiology of monocytic leukemias

Analysis of Ikaros Family Splicing Variants in Human Hematopoietic Lineages

Transcription factors from the Ikaros family are involved in lymphocyte differentiation and have a critical role at specific check points of the haemopoietic pathway. However, how developmentally regulated changes are reflected in gene expression programs of lymphocyte differentiation is not well understood. It has been suggested that disregulation of transcription factors from the Ikaros family is associated with the development of different human leukemias. In this work we analyzed the state of Ikaros family members in different leukemic cells with the aim to explore the transcriptional control of human hematopoietic lineages and shed some new light on our understanding of transcription factor significance in human leukemias. By means of RT-PCR and specific primers we investigated the expression of Ikaros, Aiolos and Helios transcription factors and their splicing variants in seven leukemia cell lines derived from different types of leukemia (ALL, CML, AML) and lymphoma (histiocytic lymphoma, Burkitt lymphoma and anaplastic large cell lymphoma). In all of the cell lines examined Ikaros was present in dominant Ik1 to Ik4 isoforms and small Ik6 isoform was absent. Aiolos was expressed in the majority of the cell lines, of both, B and T origin, in the form of the full length Aio1. Helios was also present only in two long isoforms Hel1 and Hel2, and was absent in one third of the lines. Similar distribution of positive and negative expression of Aiolos and Helios found in various types of leukemias could implicate common pathways of their regulation

Divergent leukaemia subclones as cellular models for testing vulnerabilities associated with gains in chromosomes 7, 8 or 18

Haematopoietic malignancies are frequently characterized by karyotypic abnormalities. The development of targeted drugs has been pioneered with compounds against gene products of fusion genes caused by chromosomal translocations. While polysomies are equally frequent as translocations, for many of them we are lacking therapeutic approaches aimed at synthetic lethality. Here, we report two new cell lines, named MBU-7 and MBU-8, that differ in complete trisomy of chromosome18, a partial trisomy of chromosome 7 and a tetrasomy of the p-arm of chromosome 8, but otherwise share the same mutational pattern and complex karyotype. Both cell lines are divergent clones of U-937 cells and have the morphology and immunoprofile of monocytic cells. The distinct karyotypic differences between MBU-7 and MBU-8 are associated with a difference in the specific response to nucleoside analogues. Taken together, we propose the MBU-7 and MBU-8 cell lines described here as suitable in vitro models for screening and testing vulnerabilities that are associated with the disease-relevant polysomies of chromosome 7, 8 and 18

Generation of specific antibodies against the rap1A, rap1B and rap2 small GTP-binding proteins. Analysis of rap and ras proteins in membranes from mammalian cells

Specific antibodies against rap1A and rap1B small GTP-binding proteins were generated by immunization of rabbits with peptides derived from the C-terminus of the processed proteins. Immunoblot analysis of membranes from several mammalian cell lines and human thrombocytes with affinity-purified antibodies against rap1A or rap1B demonstrated the presence of multiple immunoreactive proteins in the 22-23 kDa range, although at strongly varying levels. Whereas both proteins were present in substantial amounts in membranes from myelocytic HL-60, K-562 and HEL cells, they were hardly detectable in membranes from lymphoma U-937 and S49.1 cyc- cells. Membranes from human thrombocytes and 3T3-Swiss Albino fibroblasts showed strong rap1B immunoreactivity, whereas rap1A protein was present in much lower amounts. In the cytosol of HL-60 cells, only small amounts of rap1A and rap1B proteins were detected, unless the cells were treated with lovastatin, an inhibitor of hydroxymethylglutaryl-coenzyme A reductase, suggesting that both proteins are isoprenylated. By comparison with recombinant proteins, the ratio of rap1A/ras proteins in membranes from HL-60 cells was estimated to be about 4:1. An antiserum directed against the C-terminus of rap2 reacted strongly with recombinant rap2, but not with membranes from tested mammalian cells. In conclusion, rap1A and rap1B proteins are distributed differentially among membranes from various mammalian cell types and are isoprenylated in HL-60 cells

Flowcytometry – A rapid tool to correlate functional activities of human peripheral blood lymphocytes with their corresponding phenotypes after in vitro stimulation

Background: While dealing with mixed in vitro lymphocyte cultures one is faced with the problem of relative contributions of different populations to the activity being studied. This is especially true in the controversy relating to the contributions of lymphocyte sub-populations to the Lymphokine Activated Killer (LAK) phenomenon. Flowcytometry can be used to highlight relative contributions of lymphocyte subpopulations towards LAK activity without resorting to difficult purification strategies. We set up long-term in vitro lymphocyte cultures, stimulated them with cytokines IL-2/ IL-12, recorded their phenotypic changes and cytotoxic activity against U-937 tumor targets. Results: The results indicated that natural killer cells (NK) constituted the predominant proliferating cell population in the cytokine stimulatedcultures. Flowcytometric evidence revealed that CD56+ T cells contributed little to LAK activity against U937 target cells as compared to cells with NK phenotype which were predominantly responsible for spontaneous killing of the tumor targets. The two cytokines, IL-2 and IL-12, had an additive effect on cell proliferation and spontaneous cytotoxicity. Conclusion: Flowcytometry can be used to rapidly delineate phenotypic changes in immune cells after stimulation and simultaneously correlate them with corresponding functional activity. This approach may find application as a initial screening tool for studying different types of cells in mixed cultures and their respective activities under stimulatory / inhibitory conditions

XYLOGLUCAN CONJUGATED FUNCTIONALIZED GRAPHENE OXIDE AS A NANO CARRIER SYSTEM FOR pH RESPONSIVE TARGETED DRUG DELIVERY OF FUCOIDAN

Objective: Marine polysaccharides are materializing in the field of biomedicine owing to its promising properties, including high biocompatibility, excellent biodegradability, nontoxic nature, abundance and low cost. Fucoidan (FU), a sulphated marine polysaccharide extracted from brown seaweed, shows a promising application prospect as an anticancer model drug. In order to enhance the stability, biocompatibility and drug loading capacity, xyloglucan was chosen as a targeting ligand, conjugated onto the surface of chitosan functionalized graphene oxide for targeted delivery of fucoidan. Methods: Firstly, Graphene oxide (GO) was prepared by modified Hummer’s method and functionalized with chitosan (CS) via amidation process, further conjugated with xyloglucan (XG). The resulting conjugate, GO-CS-XG, was used to deliver fucoidan through a nanocarrier drug delivery method. The developed GO-CS-XG-FU nanosystem was analyzed for its physiochemical characterization, morphology, hemolytic activity, anti-inflammatory and anticancer activity. Results: The FU loading efficiency and capacity were 75.7% and 83.4%, respectively. XG ligands on the nanoparticle may lead the nanoparticles to actively target cancer cells. Hemolytic activity of the FU-loaded GO-CS-XG nanosystem shows negligible activity, thus making it a potential candidate for biomedical applications. In vitro drug release analysis of FU from GO-CS-XG was lesser at physiological pH but under acidic conditions, it was significantly increased. Results of in vitro cell viability studies indicate that the efficiency of fucoidan was improved upon conjugation with the nanosystem (GO-CS-XG) against human histiocytic lymphoma (U 937) cell line. Conclusion: As a result, we propose a new multifunctional graphene-based targeted platform by using xyloglucan polysaccharide as targeting nanomaterial for pH-responsive anticancer drug delivery with high efficacy