• Journal of Life Science
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• v.17 no.4 s.84
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• pp.552-560
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• 2007

Histone deacetylase (HDAC) is overexpressed in a variety of cancers and is closely correlated with oncogenic factors. HDAC inhibitors such as trichostatin A(TSA) and sodium butyrate (Na-B) have been shown to induce apoptosis in vitro and in vivo in many cancer cells. The anti-apoptotic Bcl-2 protein has the remarkable ability to prevent cell death and Bcl-2 overexpression has been reported to protect against cell death. We previously reported that the apoptotic cell death of human leukemic U937 cells by TSA and Na-B treatment was associated with the down-regulation of Bcl-2 expression and activation of caspases. In the present study, we investigated the effects of Bcl-2 overexpression on the growth inhibition, cell cycle arrest and apoptosis induced by TSA and Na-B in U937 cells. TSA-induced growth inhibition, cell cycle arrest and apoptosis were significantly attenuated in Bcl-2 overexpressing U937/Bcl-2 cells however Na-B did not affected. Induction of apoptosis by TSA was accompanied by down-regulation of Bcl-2 expression, activation of caspase-3, -8 and -9, and degradation of DNA fragmentation factor/inhibitor of caspase-activated DNase, which was blocked by the overexpression of Bcl-2. Collectively, these findings suggest that ectopic expression of Bcl-2 appeared to inhibit TSA-induced apoptosis by interfering with inhibition of Bcl-2 and caspase activation.

• Journal of Marine Bioscience and Biotechnology
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• v.1 no.2
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• pp.63-70
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• 2006

Natural product compounds are the source of numerous therapeutic agents. The marine environment produces natural products from a variety of structural classes exhibiting activity against numerous disease targets including anticancer agents. Among these, pectenotoxin-2 (PTX-2), which was first identified as a cytotoxic entity in marine sponges, which depolymerizes actin filaments, was found to be highly effective and more potent to activate an intrinsic pathway of apoptosis in p53-deficient tumor cells compared to those with functional p53 both in vitro and in vivo. However, the anti-proliferative mechanism of the compound at non-cytotoxic concentrations has not yet been explored. In the current study, we sought to investigate anti-proliferation and apoptosis of PTX-2 against U937 human leukemic cells and its underlying molecular mechanism. Exposure of U937 cells to PTX-2 resulted in growth inhibition and induction of apoptosis in dose- and time-dependent manner as measured by MTT assay, fluorescent microscopy and flow cytometric analysis. The anti-proliferative effect of PTX-2 was associated with a marked increase in the expression of cyclin-dependent kinase p21 (WAF1/CIP1) mRNA which was tumor suppressor p53-independent. The increase in apoptosis was connected with a time-dependent down-regulation of anti-apoptotic Bcl-XL and inhibitor of apoptosis proteins (IAPs) family such as XIAP and cIAP-2. Though additional studies are needed, these findings suggested that PTX-2-induced inhibition of U937 cells was associated with the induction of apoptotic cell death and the results provided important new insights into the possible molecular mechanisms of the anti-cancer activity of PTX-2.

• Korean Journal of Pharmacognosy
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• v.33 no.1 s.128
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• pp.29-34
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• 2002

Albizzia julibrissin belonging to the family Leguminosae has been used for the treatment of contusion, sore throat, amnesia, and insomnia in Oriental traditional medicine. The water extract of A. julibrissin induced apoptosis in Jurkat T-acute lymphoblastic leukemia (ALL) cells as measured by cell morphology. The capability of this herb medicine to induce apoptosis was associated with proteolytic cleavage of specific target protein such as beta-catenin protein suggesting the possible involvement of caspases. The purpose of the present study is also to investigate the effect of A. julibrissin on cell cycle progression. Our results showed that GI checkpoint related gene products (cyclin D1, cyclin dependent kinase 4, retinoblastoma, E2F1) were decreased in their protein levels in a dose-dependent manners after treatment of the extract. These results indicate that the increase of apoptotic cell death by A. julibrissin may be due to the inhibition of cell cycle progression in wild type p53-lacking Jurkat cells.

• YAKHAK HOEJI
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• v.45 no.6
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• pp.730-738
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• 2001

Apoptosis is a morphologically and biochemically distinct form of cell death that occurs in many different cell types in a wide variety of organisms. Ajbizzia julibrissin belonging the family Leguminosae has been used for the treatment of contusion, sore throat, amnesia, and insomnia in oriental traditional medicine. This study investigates whether the water extract off julibrissin induce apoptotic cell death in Jurkat T-acute lymphoblastic leukemia (ALL) cells. Jurkat cells were increased inhibitions of cell viability in a concentration-dependent manner by A julibrissin. This herbal medicine also caused apoptosis as measured by cell morphology and DNA fragmentation. The capability oft julibrissin to induce apoptosis was associated with proteolytic cleavage of specific target protein such as poly (ADP-ribose) polymerase (PARP) protein suggesting the possible involvement of caspases. Our result skewed that Bcl-2 and Bax protein levels were not changed in all A julibrissin-treated groups compared to control group. These results suggest that A julibrissin-mediated apoptosis is independent with Bcl-2 related signaling pathway in this cells.

• YAKHAK HOEJI
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• v.37 no.1
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• pp.89-94
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• 1993

In order to find out a proper connecting bridge between 5-fluorouracil(5-FU) and a macromolecule such as a polypeptide, potentially hydrolytic N$^{1}$-derivartives of 5-FU have been systhesized and evaluated for their biological activity. When tested with in vitro leukemic L$_{1210}$ cells all the obtained derivartives exhibited slightly higher antitumor activity than the parent 5FU. Among them the N$^{1}$ -carbamoyl analogue 2 and N$^{1}$-acetamido analogue 6b showed 50% inhibition of the L$_{1210}$ cell growth at the concentrations of 5.01$\times$10$^{-8}$M and 1.03$\times$10$^{-7}$M, respectively. When tested against sarcoma 180 tumor cells inoculated into mice, the compounds 2 and 6b exhibited, respectively, 62% and 54% inhibition of the solid tumor growth at the 5-time doses of 100 mg/kg/day. Both compounds, N$^{1}$-carbamoyl analogue 2 and N$^{1}$-acetamido analogue 6b, realeased the parent 5-FU when incubated in the L$_{1210}$ cell cultural media for 5 hrs.

• Molecules and Cells
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• v.41 no.5
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• pp.444-453
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• 2018

Aberrations in histone modifications are being studied in mixed-lineage leukemia (MLL)-AF9-driven acute myeloid leukemia (AML). In this study, we focused on the regulation of the differentiation of the MLL-AF9 type AML cell line THP-1. We observed that, upon phorbol 12-myristate 13-acetate (PMA) treatment, THP-1 cells differentiated into monocytes by down-regulating Aurora kinase A (AURKA), resulting in a reduction in H3S10 phosphorylation. We revealed that the AURKA inhibitor alisertib accelerates the expression of the H3K27 demethylase KDM6B, thereby dissociating AURKA and YY1 from the KDM6B promoter region. Using Flow cytometry, we found that alisertib induces THP-1 differentiation into monocytes. Furthermore, we found that treatment with the KDM6B inhibitor GSK-J4 perturbed the PMA-mediated differentiation of THP-1 cells. Thus, we discovered the mechanism of AURKA-KDM6B signaling that controls the differentiation of THP-1 cells, which has implications for biotherapy for leukemia.

• Natural Product Sciences
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• v.13 no.2
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• pp.169-173
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• 2007

Luteolin is a major flavonoid of Lonicera japonica and has anti-inflammatory effect. The activation of proteinase-activated receptor (PAR)-2 and -4 by trypsin appears to play a role in inflammation, In the present study, we examined the inhibitory effects of luteolin on activation of trypsin-induced human leukemic mast cells (HMC-1). HMC-1 cells were stimulated with trypsin, PAR-2 and PAR-4 agonist, in the presence or absence of luteolin. The level of TNF-${\alpha}$ secretion was measured by enzyme-linked immunosorbent assay (ELISA). The expression of tryptase and phosphorylated-extracellular signal-regulated kinase (ERK) were assessed by Westem blot analysis. Moreover, trypsin activity was measured by the substrate Bz-DL-Arg-p-nitroanilide (BAPNA). TNF-${\alpha}$ secretion and Tryptase expression in trypsin-stimulated HMC-1 cells were markedly inhibited by pretreatment of luteolin. Furthermore, the pretreatment of luteolin resulted in the reduction of ERK phosphorylation and trypsin activity. These results suggest that luteolin might has the inhibitory effects on the PAR-2 and -4-dependent inflammation.

• IMMUNE NETWORK
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• v.6 no.4
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• pp.179-184
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• 2006

Background: Identification of antigen-specific T cells has yielded valuable information on pathologic process and the disease state. Assays for quantification of inflammatory cytokines or lytic-granule molecules have been generally used to evaluate antigen specific T cell response, however their applicability have been hampered due to the limited source of autologous antigen-presenting target cells (APC). Methods: K562, a leukemic cell line deficient of human leukocyte antigen (HLA), was transfected with a gene encoding HLA-A*02 (K562/ A*02) and its function as stimulator cells in inducing activation of HLA-matched T cells was evaluated by IFN-${\gamma}$ enzyme linked immunospot (ELISPOT) assay. Results: The stable transfectant K562/ A*02 pulsed with HLA- A*02 restricted peptide could specifically induce IFN-${\gamma}$ secretion by CD8+ T cells compared to no detectable secretion by CD4+ T cells. However, CD56+ NK cells secreted IFN-${\gamma}$ in both K562/ A*02 with peptide and without peptide. The number of IFN-${\gamma}$ secreted CD8+ T cells was increased according to the ratio of T cells to K562 and peptide concentration. Formalin-fixed K562/ A*02 showed similar antigen presenting function to live K562/ A*02. Moreover, K562/ A*02 could present antigenicpeptide to not only A*0201 restricted CD8+ T cells but also CD8+ T cells from A*0206 donor. Conclusion: These results suggest that K562/ A*02 could be generally used as target having specificity and negligible background for measuring CD8+ T cell responses and selective use of K562 with responsder matched HLA molecules on its surface as APC may circumvent the limitation of providing HLA-matched autologous target cells.

• Journal of Marine Bioscience and Biotechnology
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• v.1 no.2
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• pp.76-83
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• 2006

Epidemiological studies have indicated that the ubiquitous consumption of seaweeds is a protective factor against some types of cancer. Previous results showed that the administration of seaweed powder or extract reduced the incidence rate of chemically induced tumorigenesis using in vivo animal model. Recently, we reported that the extracts of Gloiopeltis furcata, a kind of Korean edible seaweed, caused he cell growth inhibition of various human cancer cell lines, among them methanol extract exhibited a relatively strong antiproliferative activity. However, the molecular mechanisms of this seaweed in malignant cells have been poorly studied until now. To elucidate this problem, we investigated the effects of methanol extract of G. furcata (MEGF) on the growth inhibition in several human cancer cell lines, and further we analyzed the effects of this extract were tested on the activity of apoptosis induction in human leukemic cells. The results demonstrated that MEGF treatment resulted in the morphological changes and the growth inhibition in a dose-dependent manner. Furthermore, MEGF potently suppresses the growth of human leukemic U937 cells by induction of apoptosis, which was associated with induction of cyclin-dependent kinase inhibitor p21(WAF1/CIP1) in a tumor suppressor p53-independent fashion and up-regulation of Fas/FasL system. Further studies will be needed to identify the active compounds that confer the anticancer activity of MEGF. Once such compounds are identified, the mechanisms by which they exert their effects can begin to be characterized.

• BMB Reports
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• v.38 no.4
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• pp.391-398
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• 2005

3-hydrogenwadaphnin (3-HK) is a new daphnane-type diterpene ester isolated from Dendrostellera lessertii with strong anti-tumoral activity in animal models and in cultures. Here, prolonged effects of this new agent on proliferation and viability of several different cancerous cell lines were evaluated. Using [$^3H$]thymidine incorporation, it was found that the drug inhibited cell proliferation and induced G1/S cell cycle arrest in leukemic cells 24 h after a single dose treatment. The cell viability of Jurkat cells was also decreased by almost 10%, 31% and 40% after a single dose treatment (7.5 nM) at 24, 48 and 72 h, respectively. The drug-treated cells were stained with acridine orange/ethidium bromide to document the chromatin condensation and DNA fragmentation. These observations were further confirmed by detection of DNA laddering pattern in the agarose gel electrophoresis of the extracted DNA from the treated cells. Treatment of K562 cells with the drug at 7.5, 15 and 30 nM caused apoptosis in 25%, 45% and 65% of the cells, respectively. Exogenous addition of $25-50\;{\mu}M$ guanosine and/or deoxyguanosine to the cell culture of the drug-treated cells restored DNA synthesis, released cell arrest at G1/S checkpoint and decreased the apoptotic cell death caused by the drug. These observations were not made using adenosine. However, the drug effects on K562 cells were potentiated by hypoxanthine. Based on these observations, perturbation of GTP metabolism is considered as one of the main reasons for apoptotic cell death by 3-HK.