Proliferation Of Daudi Cells Research Articles

ANTI-PROLIFERATIVE EFFICACY OF ALSTONIA SCHOLARIS (L.) R.BR. EXTRACT ON CULTURED DAUDI CELLS: AN IN VITRO APPROACH

Objective: The aim of this study is to observe the apoptosis of ALSTONIA SCHOLARIS (L.) R.Br. against Daudi cells and to study its primary mechanism. Materials and Methods: Antiproliferative activity of cultured Daudi cells was evaluated using 3-(4, 5-dimethylthiazol-2-yl)-2, 5-diphenyltetrazolium bromide assay in a dose- and time-dependent manner after treatment with the hydroalcoholic extract of A. scholaris. Trypan blue viability assay was also performed. Apoptosis induction in the cells post treatment was determined by DNA fragmentation assay, Agarose gel electrophoresis, and Acridine orange/Ethidium bromide dual staining. Protein isolation and analysis was carried out using the standard polyacrylamide gel electrophoresis protocols. Results: The extracts inhibited the growth and proliferation of Daudi cells through induced cell death, which was dose-dependent and time-dependent. The IC50 value was found to be 260 µg/ml after 72 h of treatment. The induction of DNA fragmentation and increase in a number of apoptotic ells post treatment suggest the possibility of apoptosis induction. A significant decrease in protein level was also observed. Conclusion: The results raise the possibility that the hydroalcoholic extract of A. scholaris could be a potent chemotherapeutic agent for the treatment of various cancers. Further evaluation of its potency as a chemotherapeutic agent is imperative.

Phyllanthus fraternus manifests potent anti-proliferative activity on cultured Daudi cells.

The aim of this study is to observe the apoptosis of Phyllanthus fraternus Webster against Daudi cells and to study its primary mechanism. Antiproliferative activity of cultured Daudi cells was evaluated using 3-(4, 5-dimethylthiazol-2-yl)-2, 5-diphenyltetrazolium bromide assay in a dose- and time-dependent manner after treatment with the hydroalcoholic extract of P. fraternus . Trypan blue viability assay was also performed. Apoptosis induction in the cells posttreatment was determined by DNA fragmentation assay, Agarose gel electrophoresis, and Acridine orange/Ethidium bromide dual staining. Protein isolation and analysis was carried out using the standard polyacrylamide gel electrophoresis protocols. The extracts inhibited the growth and proliferation of Daudi cells through induced cell death, which was dose-dependent and time-dependent. The IC50 value was found to be 220 μg/ml after 72 h of treatment. The induction of DNA fragmentation and increase in a number of apoptotic cells posttreatment suggest the possibility of apoptosis induction. A significant decrease in protein level was also observed. The results raise the possibility that the hydroalcoholic extract of P. fraternus could be a potent chemotherapeutic agent for the treatment of various cancers. Further evaluation of its potency as a chemotherapeutic agent is imperative.

HIgD promotes human Burkitt lymphoma Daudi cell proliferation by accelerated G1/S transition via IgD receptor activity.

The aim of the present study was to investigate the role and molecular mechanism of human IgD (hIgD) on the proliferation of human Burkitt lymphoma Daudi cells in vitro. Logarithmically growing Daudi cells were treated with hIgD for different time periods, and cell proliferation was evaluated by cell counting kit-8 (CCK-8) assay. The expressions of Daudi surface markers and IgD receptor (IgDR) as well as cell cycle and apoptosis were measured by flow cytometry analysis. Our results showed that hIgD stimulation induced proliferation and IgDR expression and reduced the apoptosis of Daudi cells. Treatment with hIgD promoted progression of the cell cycle at the G1/S transition, and this was accompanied by upregulation of c-myc, cyclin D3, and CDK6 as well as downregulation of p16 mRNA and protein levels. Moreover, hIgD treatment also upregulated the expression of tyrosine phosphorylation of 70 kDa protein (IgDR) and p-Lyn. Taken together, these results indicate that hIgD can induce Daudi cell proliferation through activating IgDR to initiate the tyrosine phosphorylation signaling cascade to accelerate the G1/S transition.

Recombinant human antibodies to IFN-α from the immune repertoires of MG/thymoma donors (83.13)

Abstract A serum titer of autoantibodies to IFN-α has been reported in several autoimmune conditions and in many cases has been shown to neutralize IFN-α. The IFN-α antibody repertoire from 10 patients with autoimmune myasthenia gravis and associated thymoma (MG/T) was characterized. Surface IgG positive memory B-cells from peripheral blood mononuclear cells (PBMC) were cultured in 384-well plates to produce assayable quantities of antibody. Sensitive antibody microarray and AlphaScreen™ binding assays were used to identify antibodies reactive with IFN-α(2a). A range of IFN-α subtype specificity profiles was observed in competition assays for binding to the 12 subtypes of IFN-α. A subset of these antibodies was expressed recombinantly after recovery of heavy and light chain variable regions by RT-PCR and these recombinant antibodies recapitulated the activities demonstrated in the B-cell culture supernatants. These antibodies fell into 2 groups, blocking binding of IFN-α(2a) to either the IFNAR2 or IFNAR1 subunit of the Type 1 interferon receptor. The ability of these antibodies to neutralize the activity of IFN-α(2a) in a Daudi cell proliferation assay was confirmed. The antibody repertoires of MG/T patients include high affinity antibodies with both broad and narrow specificities for the different subtypes of IFN-α. These function-blocking human antibodies may have therapeutic utility in IFN-α dependent diseases such as SLE.

Preparation and Characterization of a Novel Chimeric Antibody Against Human CD40 with the Potential to Inhibit Daudi Cell Proliferation

5C11, a murine monoclonal antibody with a high specificity for human CD40 molecule, is a promising candidate for cancer targeting therapy. We have therefore attempted to construct a humanized antibody of 5C11 to minimize its immunogenicity for potential clinical use. A chimeric version of 5C11 (ch-5C11) was generated by transferring these mouse variable regions onto a human framework. This chimeric antibody retained reactivity to human CD40. In vitro, ch-5C11 could effectively inhibit B lymphoma Daudi cell proliferation, suggesting that it might have the potential to be developed for future clinical use.

Trichostatin a regulates hGCN5 expression and cell cycle on Daudi cells in vitro

The expression of human general control of amino acid synthesis protein 5 (hGCN5) in human Burkitt's lymphoma Daudi cells in vitro, effects of Trichostatin A (TSA) on cell proliferation and apoptosis and the molecular mechanism of TSA inhibiting proliferation of Daudi cells were investigated. The effects of TSA on the growth of Daudi cells were studied by 3-(4, 5-dimethyl-2-thiazolyl)-2,5-diphenyl-2H-tetrazolium (MTT) assay. The effect of TSA on the cell cycle of Daudi cells was assayed by a propidium iodide method. Immunochemistry and Western blot were used to detect the expression of hGCN5. The proliferation of Daudi cells was decreased in TSA-treated group with a 24 h IC50 value of 415.3979 microg/L. TSA induced apoptosis of Daudi cells in a time- and dose-dependent manner. Treatment with TSA (200 and 400 microg/L) for 24 h, the apoptosis rates of Daudi cells were (14.74+/-2.04) % and (17.63+/-1.25) %, respectively. The cell cycle was arrested in G0/G1 phase (50, 100 microg/L) and in G2/M phase (200 microg/L) by treatment with TSA for 24 h. The expression of hGCN5 protein in Daudi cells was increased in 24 h TSA-treated group by immunochemistry and Western blot (P<0.05). It was suggested that TSA as HDACIs could increase the expression of hGCN5 in Daudi cells, and might play an important role in regulating the proliferation and apoptosis of B-NHL cell line Daudi cells.

Survivin—An attractive target for RNAi in non-Hodgkin's lymphoma, Daudi cell line as a model

RNA interference (RNAi) has been widely used in tumor gene therapy, antivirus and gene drug selection. Survivin gene is highly expressed in non-Hodgkin's lymphoma (NHL) tissues and high malignancy Burkitt's lymphoma cell line-Daudi and it is regarded as a potential target of gene therapy for NHL. This study used a vector-based short hairpin RNA (shRNA) technique to explore the effect of RNAi-mediated survivin gene silencing on apoptosis and proliferation of Daudi cells. Recombinant plasmid survivin-shRNA was transfected into Daudi cells transiently and stably. The expression of survivin was detected by semi-quantitative reverse transcription-polymerase chain reaction (RT-PCR) and Western blot. The apoptosis of Daudi cells after transfection were evaluated by flow cytometry. After transfection of survivin-shRNA, the levels of survivin mRNA were significantly reduced by 64.20% (transient transfection) and 62.32% (stable transfection), respectively; The levels of survivin protein were significantly reduced by 63.50% (transient transfection) and 61.88% (stable transfection); compared with control-shRNA and PBS treated groups. Apoptosis of Daudi cells were significantly higher in the transfection group than in the control group, respectively 21.30 ± 2.96% (transient transfection) and 19.10 ± 2.15% (stable transfection). In conclusion, it was suggested that survivin could be an attractive target for new anti-cancer intervention of NHL and vector-based survivin-shRNA could effectively reduce the expression of survivin and induce cell apoptosis and growth inhibition of NHL cells.

Regulating expressions of cyclin D1, pRb, and anti-cancer effects of deguelin on human Burkitt's lymphoma Daudi cells in vitro1

To investigate anticancer effects and molecular mechanism of deguelin on human Burkittos lymphoma Daudi cells in vitro and compare the cytotoxicities of deguelin on Daudi cells and human peripheral blood monocular cells (PBMC). The effects of deguelin on the growth of Daudi cells were studied by 3-(4, 5-dimethyl-2-thiazolyl)-2,5-diphenyl-2H-tetrazolium (MTT) assay. Apoptosis were detected through Hoechst 33258 staining and Annexin V/PI double-labeled cytometry. The effect of deguelin on the cell cycle of Daudi cells were studied by a propidium iodide method. The expressions of cyclin D1 and pRb were checked by Western blot. The proliferation of Daudi cells were decreased in deguelin-treated group with a 24-h IC50 value of 51.55 nmol/L. Deguelin induced Daudi cells apoptosis was in a time- and dose-dependent manner. G0/G1 phase increased and S phase decreased in Daudi cells treated with deguelin. With deguelin 0, 5, 10, 20, and 40 nmol/L treatment for 24 h, G0/G1 phase increased from 37.34% to 56.56%, whereas S phase decreased from 37.72% to 21.36%. PBMC was less sensitive to the cytotoxic effect of deguelin than Daudi cells. The expression of cyclin D1 and pRb protein were decreased sharply in Daudi cells treated with deguelin. Deguelin is able to inhibit the proliferation of Daudi cells by regulating the cell cycle that arrested cells at G0/G1 phase and inducing the cell apoptosis. Moreover, deguelin selectively induced apoptosis of Daudi cells with low toxicity in PBMC. The antitumor effects of deguelin were related to down-regulating the expression of cyclin D1 and pRb protein.

Efficacy of anti-CD20 chimeric Fab’ fragment on proliferation of B lymphoma cells

The variable domain of heavy chain (VH) and light chain (VL) genes of anti-CD20 monoclonal antibody HI47 were cloned from anti-CD20 ScFv expression vector pCANBTEcd20 by PCR and ligated into vector pYZF to construct chimeric anti-CD20 Fab’ fragment expression vector pYZFcd20. Chimeric anti-CD20 Fab’ fragment was expressed inE. coli 16C9 and purified by protein G affinity chromatography. Competitive inhibition assay showed that anti-CD20 Fab’ fragment inhibited binding of HI47 to CD20 on the surface of Daudi cells. Results from MTT assay indicated that chimeric anti-CD20 Fab’ fragment inhibited the proliferation of Daudi cells, IC50 = 69 μg/mL. Affinity of chimeric anti-CD20 Fab’ fragment was determined, Ka was about 8.9×108 (mol/L)−1.

The antiproliferative and antiviral activities of IFN-tau variants in human cells.

The IFN-tau are type I IFN expressed by the early trophoblast of cattle and sheep but have activity on human cells and have been predicted to have potential therapeutic value. We have compared a series of mutant bovine and ovine IFN-tau with regard to their ability to inhibit the proliferation of Daudi cells and to evoke an antiviral (AV) response in WISH cells. Whereas Daudi cell growth was inhibited by Bo-IFN-tau1 in the 1 nM range, WISH cells were much less responsive, requiring exposure to 150 nM for protection against vesicular stomatitis virus. Replacement of lysines at positions 34, 107, 121, and 132 in Bo-IFN-tau, which are in regions predicted to interact with the type I receptor, led to modest but significant alterations in antiproliferative (AP) and AV activities. Replacement of the lysine residues at 160 and 164 had marked effects on biopotency, with K160 being particularly important. The different IFN-tau were able to activate the transcription factors ISGF3 and AAF (GAF) in Daudi cells at concentrations that correlated reasonably well with their AP potencies. Stat activation occurred in WISH cells in response to approximately 2 nM Bo-IFN-tau1, but ISGF3 formation could not be demonstrated even at the 100-fold higher IFN-tau concentrations that gave viral protection. Pretreatment of WISH cells with Hu-IFN-gamma allowed ISGF3 formation to be observed in response to subsequent treatment with Bo-IFN-tau1 or type I human IFN but did not increase the AV responsiveness of the cells. No evidence was found that IFN-tau elicit uniquely different responses on human cells than type I Hu-IFN, except they are much less potent. The data emphasize the importance of a region near the carboxyl terminus for the functional activity of type I IFN, and that although ISFG3 formation may be necessary, its mere presence is not sufficient to provide an antiviral response.

Phorbol ester-induced inhibition of proliferation of Daudi Burkitt's lymphoma cells by impairment of cytokinesis

The phorbol ester 12- O-tetradecanoylphorbol-13-acetate (TPA) exerts a dose-dependent effect on Daudi cell proliferation. A low concentration has a slight mitogenic effect but higher concentrations inhibit proliferation. The inhibitory effect is associated with increases in cell size, macromolecular content, and incorporation of precursors into RNA and protein. Cell cycle analysis indicates that TPA at 1–10 n M leads to an apparent accumulation of cells in G 2 M phase. However, within this population a significant proportion of cells undergo nuclear division but fail to carry out cytokinesis, giving rise to cells with two or more nuclei. Consistent with this, DNA synthesis continues in cells which cease to divide in the presence of TPA. The ability of the phorbol ester to inhibit proliferation can thus be attributed mainly to an inhibition of cytokinesis rather than DNA replication

Modification of the clonogenic assay for the detection of lymphokine activated killer cell activity

The soft agar clonogenic assay using [ 3H]thymidine uptake as an endpoint was adapted for the detection of human LAK activity against the Daudi lymphoma cell line and human tumor cells obtained by biopsy. Using Daudi cells as the target population the modified agar assay was more sensitive than the conventional 4 h 51Cr release assay. Use of a single layer agar assay allowed the assessment of LAK cytotoxic/cytostatic activity against Daudi lymphoma cells after cell to cell contact, while a two layer system permitted evaluation of the role of soluble mediators in LAK/target cell interactions. This study shows that LAK cells can either kill or inhibit the proliferation of Daudi cells by two mechanisms: one which requires cell-to-cell contact, and a second via soluble mediators. As determined by the use of neutralizing antisera, the soluble factor(s) are not tumor necrosis factor and interferon-γ. Of the nine individual human tumor samples obtained by biopsy, 89% were sensitive to allogeneic LAK cells when the two populations were admixed. Of these nine tumors 44% were inhibited by LAK-derived soluble factors. The soft agar assay system should serve as a useful tool for determining the sensitivity of human tumors to LAK cells and for studying the mechanisms of LAK anti-tumor activity.

Antibodies against a peptide representative of a conserved region of human IFN-alpha. Differential effects on the antiviral and antiproliferative effects of IFN.

mAb generated from mice immunized with a synthetic peptide representative of a conserved region (amino acids 133 to 147) of human IFN-alpha are described. Antisera from mice immunized with the peptide coupled to keyhole limpet hemocyanin were able to specifically bind to the peptide and also to bind and precipitate human IFN-alpha. Binding of the antibodies to IFN-alpha was inhibited by the immunizing peptide, but not by an unrelated peptide. Immunized mice were used to obtain three hybridomas producing mAb able to recognize both the immunizing peptide and human IFN-alpha, as determined by RIA and immunoprecipitation. These antibodies also neutralized the antiviral effect of human leukocyte IFN. In contrast, none of the mAb significantly affected the inhibition of Daudi cell proliferation induced by IFN-alpha.

Inhibition of polypeptide chain initiation in Daudi cells by interferons. Evidence that activity of initiation factor eIF-2 and availability of mRNA are unimpaired

The accompanying paper [McNurlan & Clemens (1986) Biochem. J. 237, 871-876] shows that the inhibition of proliferation of Daudi cells by human interferons is associated with impairment of the overall rate of protein synthesis. We have examined whether two of the mechanisms which are believed to control translation in interferon-treated virus-infected cells may be responsible for the inhibition of protein synthesis during the antiproliferative response in these uninfected cells. Although the rate of polypeptide chain initiation is lower in interferon-treated Daudi cells, as indicated by the disaggregation of polysomes, there is no significant inhibition of activity of initiation factor eIF-2 or of [40 S . Met-tRNAf] initiation complex formation in cell extracts. The phosphorylation state of the alpha subunit of eIF-2 remains unaltered. There is no major decrease in mRNA content as a proportion of total RNA up to 4 days of interferon treatment, as judged by poly(A) content, although the amount of total mRNA/10(6) cells eventually declines. The mRNA present in extracts from interferon-treated cells remains translatable when added to an mRNA-dependent reticulocyte lysate system. We conclude that neither the interferon-inducible eIF-2 protein kinase pathway nor the 2',5'-oligo(adenylate)-ribonuclease L pathway are responsible for the inhibition of polypeptide chain initiation. Rather, the data suggest impairment at the level of formation of [80 S ribosome X mRNA] initiation complexes.

Inhibition of cell proliferation by interferons. 2. Changes in processing and stability of newly synthesized DNA in human lymphoblastoid (Daudi) cells.

The inhibition of proliferation of Daudi cells in culture by human interferons is characterized by a change in the kinetics of labelling of different size classes of newly synthesized DNA. Initially, labelled precursors are incorporated exclusively into small DNA (Okazaki fragments) in both control and interferon-treated cells, as revealed by alkaline sucrose gradient centrifugation. In the interferon-treated cells, there is enhanced labelling of this small DNA after short periods of incorporation and slower conversion to larger DNA size classes, in comparison with the DNA of control cells. This effect is apparent after 12 h of interferon treatment, coincident with the onset of the inhibition of cell proliferation. It becomes progressively more marked up to 4 days, by which time cell growth has ceased completely. Experiments using bromodeoxyuridine as a density label and analysis of radioactive DNA on caesium chloride/caesium sulphate gradients also reveal that some newly replicated DNA may be unstable and may turn over within a few hours of its synthesis. The label derived from DNA breakdown is efficiently reincorporated into newly synthesized molecules. It is suggested that interferon treatment inhibits DNA replication by activating DNA turnover rather than by directly inhibiting synthesis. This effect, together with the progressive retardation of conversion of Okazaki fragments to larger DNA, may lead to the eventual failure of cell proliferation.

Inhibition of cell division by interferons. The relationship between changes in utilization of thymidine for DNA synthesis and control of proliferation in Daudi cells

Inhibition of the proliferation of Daudi cells by exposure to human lymphoblastoid interferons is associated with an early and marked decrease in the incorporation into DNA of exogenous [3H]thymidine when cells are incubated with trace amounts of this precursor. In contrast, incorporation of exogenous deoxyadenosine into DNA is unchanged under the same conditions. Interferon treatment results in a lowering of thymidine kinase activity, an effect which may be largely responsible for the inhibition of incorporation of labelled thymidine into DNA. At higher concentrations of exogenous thymidine, which minimize the contribution of intracellular sources to the dTTP pool, the inhibition of thymidine incorporation is abolished. Under conditions in which exogenous thymidine is rigorously excluded from the medium or, conversely, in which cells are entirely dependent on exogenous thymidine for growth, the magnitude of the inhibition of cell proliferation by interferons is the same as under normal culture conditions. We conclude that, even though cell growth is impaired, the rate of DNA synthesis is not grossly inhibited up to 48 h after commencement of interferon treatment. Furthermore, changes in neither the utilization of exogenous thymidine nor the synthesis of nucleotides de novo are responsible for the effect on cell proliferation.

Biological properties of human interferon beta 1 synthesized in recombinant bacteria.

Human fibroblast interferon, designated IFN-beta 1, has been produced in E. coli by direct expression of the cloned cDNA coding for the mature polypeptide. Bacterial lysates from recombinant cultures contain a polypeptide with an apparent molecular weight of 17,500 that corresponds in size to the unglycosylated IFN-beta 1 molecule. The latter could be specifically immunoprecipitated by antibodies to purified natural IFN-beta and could inhibit the replication of Herpes simplex virus types 1 and 2 in many different cell lines. Like the natural fibroblast IFN-beta, the bacterial IFN-beta 1 was active in many human cell lines, less active in a monkey cell line and inactive in rabbit and mouse fibroblasts. The antibody titre required to neutralise the anti-herpes activity of both IFN preparations was similar suggesting that they have the same specific activities. Similarly, the bacterial IFN-beta 1 was equally active in inhibiting the proliferation of Daudi cells grown in culture. Bacterial IFN-beta 1 was also capable of enhancing natural killer cell activity and antibody-dependent cellular cytotoxicity in vitro. Thus, IFN-beta 1 produced in recombinant bacteria displays a large range of biological properties ascribed to the natural fibroblast IFN-beta molecule.

Characteristics of in vitro antiproliferation activity of human interferon-beta.

We compared the in vitro antiproliferative activity of highly purified interferon (IFN)-beta (greater than 10(7) U protein/mg in antiviral activity) with that of IFNs-alpha and lymphoblastoid, using human cells of malignant and non-malignant origin. IFN-beta was the least active of three IFNs in suppressing Daudi cell proliferation. Three hematological cells other than Daudi cells cultivated in suspension were insensitive to each of three IFNs. IFN-beta was more active than IFNs-alpha and lymphoblastoid in suppressing all eight epithelioid cells tested and, particularly with respect to five epithelioid cells sensitive to IFN, IFN-beta was seven to 49 times as active as IFN-alpha. These results indicate that suppression of cell proliferation by IFN depends not only on the target cell species but also on the IFN species, and emphasize the need for careful selection of the most appropriate IFN species in therapy. We found that the antiproliferative characteristics of the present IFN-beta preparation were consistent with those reported previously, supporting the idea that IFN-beta molecules in the present preparation were responsible for suppressing cell proliferation. The antiproliferation activity of our preparation was species-specific but not selective for cells of malignant origin; it was absorbable by IFN-sensitive but not by IFN-insensitive cells; and it was achieved by a cytostatic effect.

Antiproliferative and antiviral activities of human leukocyte interferons

The antiproliferative effects of purified human leukocyte interferons were measured by their ability to inhibit cell multiplication of the human lymphoblastoid Daudi cell line. The growth-inhibitory and antiviral activities fractionate together throughout the purification of leukocyte interferon. In all cases, those fractions which exhibited antiviral activity also inhibited proliferation of Daudi cells. The final stage of protein purification, high-performance liquid chromatography on octyl-silica particles (pH 4.0), separated at least eight species of leukocyte interferon, all of which possessed growth-inhibitory activity. Because these two biological activities purify together and because the homogeneous species exhibit both activities, we conclude that the antiproliferative and the antiviral activities are both intrinsic properties of these human leukocyte interferons. However, the ratio of the growth-inhibitory to antiviral activity was not constant among the species. In addition, the ratio of the antiviral activity on human cells to that on bovine cells varied from species to species. We conclude that the individual members of the family of human leukocyte interferon proteins differ in structure and that these structural differences manifest themselves as variations in their intrinsic biological activities.