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ABSTRACT: Dendritic cells (DCs) are potent antigen-presenting cells that can be matured in vitro from immature dendritic cells (iDCs) in the presence of several biological agents such as cytokine cocktail, CD40L, TNF-a and antigen loading, which are necessary and achieved using various protocols, such as lipofection, passive pulse or electroporation. However, these DCs maturation protocols may cause with a significant loss of cells because of cellular attachment and spreading during culturing. Some biomaterials that influence adhesion and development of cells have been used in cell culture techniques, and it was thought that they might be applied on the culture of DCs. In this study, we used polyHEMA, which is a hydrogel coating biomaterial that prevents DCs from adherence, and investigated whether hydrogel coating affects the maturation of iDCs. The efficiency in the generation of mDCs was improved through hydrogel coating procedure and a dendritic cell maturation marker, CD83, was significantly increased in hydrogel-coated culture condition. The antigen-loaded mDCs from electroporation were further expressed the CD83. The mDCs generated in the hydrogel-coated culture condition showed more, longer and thicker dendrites, and produced more amounts of cytokines such as IL-12 and IFN-γ. Therefore, it was suggested that the hydrogel-coated culture condition could improve function of mDCs. Cheol-Hun Son and Jae-Ho Bae contributed equally to this work.
Immunological Investigations 03/2013; · 1.47 Impact Factor
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ABSTRACT: Decitabine (5-aza-2'-deoxycytidine), an inhibitor of DNA methyltransferases, has a wide range of anti-metabolic and anti-cancer activities. Decitabine also induces cell cycle arrest at G2/M phase and apoptosis in human cancer cells. However, the cellular and molecular mechanisms of this cell cycle arrest are poorly understood. In the present study, we investigated the roles of the tumor suppressor p53 and the cyclin-dependent kinase (Cdk) inhibitor p21 following decitabine-induced G2/M arrest in human cancer cells. DNA flow cytometric analyses indicated that decitabine induced a G2/M arrest in AGS gastric and A549 lung carcinoma cell lines, which have wild type p53. Western blot analyses using whole cell lysates from AGS cells demonstrated that decitabine treatment did not change the steady-state level of Cdks and Cdk inhibitor p27, but it partially inhibited expression of cyclin A, cyclin B1, and Cdc25C proteins. However, similar results were found using the A549 cell line, where decitabine induced a dramatic up-regulation of both p53 and p21 expression, and the increased levels of p21 were associated with increased binding of p21 with Cdks, cyclin A, and cyclin B1. Knockdown of p53 by small interfering RNA (siRNA) markedly abolished p53 induction by decitabine in AGS cells, yet p53 siRNA had no attenuating effect on p21 induction. In addition, depletion of p21 expression with siRNA, but not p53, significantly attenuated decitabine-induced G2/M arrest. We also observed that decitabine strongly induced G2/M arrest associated with p21 induction in both p53 allele-null (-/-) HCT116 and wild type p53 (+/+) HCT116 cell lines. Therefore, our data indicated that p21 plays a crucial role in decitabine-induced G2/M arrest and operates in a p53-independent manner.
Biomedicine & pharmacotherapy = Biomedecine & pharmacotherapie 02/2013; · 2.24 Impact Factor
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ABSTRACT: Recently, chemotherapy and radiotherapy are known to directly affect some immunosuppressive barriers within a tumor microenviroment. We used cyclophosphamide (CTX), which is known to enhance the immune response by suppressing CD4CD25 regulatory T cells (Treg cells) when used at a low dose, as a chemotherapeutic agent to provide a synergic effect in the irradiation and dendritic cells (DC) combination therapy. Some previous studies observed that a single-dose CTX treatment significantly reduced the number of Treg cells in 3-5 days, however, the reduced Treg cells increased rapidly after 5 days. To overcome the disadvantages of a single-dose CTX, we used 30 mg/kg dose of CTX, which was treated intraperitoneally to mice 3 days before every immature DC (iDC) injection (known as "metronomic schedule CTX"). Irradiation was applied at a dose of 10 Gy to the tumor on the right thigh by a linear accelerator. Then, iDC was intratumorally injected into the irradiated tumor site. Growth of a distant tumor on the right and left flank was suppressed by an injection of iDC into the irradiated tumor, and this effect was increased by the metronomic schedule CTX. Also, combinations treated with the metronomic schedule CTX and ionizing radiation (IR)/iDC, showed the longest survival time compared with other groups. This antitumor immune response of IR/iDC was improved by metronomic schedule CTX and this result was associated with decreasing the proportion of CD4CD25 Treg cells and increasing the number of tumor-specific interferon-γ-secreting T cells. Our results demonstrated that metronomic schedule CTX improves the antitumor effect of immunization with an injection of DC s into the irradiated tumor.
Journal of immunotherapy (Hagerstown, Md.: 1997) 10/2012; 35(8):607-14. · 3.20 Impact Factor
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ABSTRACT: The DNA methyltransferase inhibitor decitabine, 5-aza-2'-deoxycytidine, has been found to exert anti-metabolic and anticancer activities when tested against various cultured cancer cells. Furthermore, decitabine has been found to play critical roles in cell cycle arrest and apoptosis in various cancer cell lines; however, these roles are not well understood. In this study, we investigated decitabine for its potential anti-proliferative and apoptotic effects in human leukemia cell lines U937 and HL60. Our results indicated that treatment with decitabine resulted in significantly inhibited cell growth in a concentration- and time-dependent manner by the induction of apoptosis. Decitabine-induced apoptosis in U937 and HL60 cells was correlated with the downregulation of anti-apoptotic Bcl-2, XIAP, cIAP-1 and cIAP-2 protein levels, the cleavage of Bid proteins, the activation of caspases and the collapse of mitochondrial membrane potential (MMP). However, apoptosis induced by decitabine was attenuated by caspase inhibitors, indicating an important role for caspases in decitabine responses. The data further demonstrated that decitabine increased intracellular reactive oxygen species (ROS) generation. Moreover, N-acetyl-L-cysteine, a widely used ROS scavenger, effectively blocked the decitabine-induced apoptotic effects via inhibition of ROS production and MMP collapse. These observations clearly indicate that decitabine-induced ROS in human leukemia cells are key mediators of MMP collapse, which leads to apoptosis induction followed by caspase activation.
International Journal of Oncology 07/2012; 41(3):910-8. · 2.40 Impact Factor
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ABSTRACT: The DNA methyltransferase inhibitor decitabine, 5-Aza-2'-deoxycytidine, possesses anti-metabolic and anticancer activities in various cancer cells. However, the biochemical mechanisms underlying decitabine-induced inhibition of invasiveness and metastasis have not been thoroughly studied. In this study, we investigated the effect of decitabine on the correlation between tightening of tight junctions (TJs) and anti-invasive activity in AGS human gastric cancer cells. Our data indicated that the inhibitory effects of decitabine on cell motility and invasiveness were associated with increased tightness of the TJ, which was demonstrated by an increase in transepithelial electrical resistance (TER). Immunoblotting results indicated that decitabine repressed the levels of the claudin proteins, major components of TJs that play a key role in the control and selectivity of paracellular transport. Furthermore, matrix metalloproteinase (MMP)-2 and -9 activity in the AGS cells was dose-dependently inhibited by treatment with decitabine, and this was correlated with a decrease in mRNA and protein expression. In addition, these effects were related to inactivation of the phosphoinositide 3-kinase (PI3K)/Akt pathway in AGS cells. In conclusion, this study suggests that TJs and MMPs are critical targets of decitabine-induced inhibition of invasiveness in AGS human gastric cancer cells.
Oncology Reports 06/2012; 28(3):1043-50. · 1.84 Impact Factor
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ABSTRACT: Diallyl disulfide (DADS), a sulfur compound derived from garlic, has various biological properties, such as anticancer, antiangiogenic and anti-inflammatory effects. However, the mechanisms of action underlying the compound's anticancer activity have not been fully elucidated. In this study, the apoptotic effects of DADS were investigated in DU145 human prostate carcinoma cells. Our results showed that DADS markedly inhibited the growth of the DU145 cells by induction of apoptosis. Apoptosis was accompanied by modulation of Bcl-2 and inhibitor of apoptosis protein (IAP) family proteins, depolarization of the mitochondrial membrane potential (MMP, ΔΨm) and proteolytic activation of caspases. We also found that the expression of death-receptor 4 (DR4) and Fas ligand (FasL) proteins was increased and that the level of intact Bid proteins was down-regulated by DADS. Moreover, treatment with DADS induced phosphorylation of mitogen-activated protein kinases (MAPKs), including extracellular-signal regulating kinase (ERK), p38 MAPK and c-Jun N-terminal kinase (JNK). A specific JNK inhibitor, SP600125, significantly blocked DADS-induced-apoptosis, whereas inhibitors of the ERK (PD98059) and p38 MAPK (SB203580) had no effect. The induction of apoptosis was also accompanied by inactivation of phosphatidylinositol 3-kinase (PI3K)/Akt and the PI3K inhibitor LY29004 significantly increased DADS-induced cell death. These findings provide evidence demonstrating that the proapoptotic effect of DADS is mediated through the activation of JNK and the inhibition of the PI3K/Akt signaling pathway in DU145 cells.
International Journal of Molecular Sciences 01/2012; 13(11):14158-71. · 2.60 Impact Factor
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ABSTRACT: In the present study, the effects of the whole skin of Venenum bufonis on apoptotic and anti-invasive activity in A549 human lung cancer cells were investigated. Treatment with extract of the whole skin of V. bufonis (SVB) resulted in a significant decrease in cell growth of A549 cells, depending on dosage, which was associated with apoptosis induction, as proved by chromatin condensation and accumulation of apoptotic fraction. SVB treatment induced expression of death receptor-related proteins, such as death receptor 4, which further triggered activation of caspase-8 and cleavage of Bid. In addition, the increase in apoptosis by SVB treatment was correlated with dysfunction of mitochondria, activation of caspase-9 and -3, downregulation of IAP family proteins, such as XIAP, cIAP-1 and cIAP-2, and concomitant degradation of activated caspase-3-specific target proteins, such as poly (ADP-ribose) polymerase and β-catenin proteins. However, z-DEVD-fmk, a caspase-3-specific inhibitor, blocked SVB-induced apoptosis and increased the survival rate of SVB-treated cells, indicating that activation of caspase-3 plays a key role in SVB-induced apoptosis. In addition, within concentrations that were not cytotoxic to A549 cells, SVB induced marked inhibition of cell motility and invasiveness. Activities of matrix metalloproteinase (MMP)-2 and MMP-9 in AGS cells were dose-dependently inhibited by treatment with SVB, and this was also correlated with a decrease in expression of their mRNA and proteins, and upregulation of tissue inhibitors of metalloproteinase (TIMP)-1 and TIMP-2 mRNA expression. Further studies are needed; however, the results indicated that SVB induces apoptosis of A549 cells through a signaling cascade of death receptor-mediated extrinsic as well as mitochondria-mediated intrinsic caspase pathways. Our data also demonstrated that MMPs are critical targets of SVB-induced anti-invasiveness in A549 cells.
International Journal of Oncology 12/2011; 40(4):1210-9. · 2.40 Impact Factor
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ABSTRACT: This study investigated the effect of ethanol extracts of Ganoderma lucidum (EGL) on the correlation between tightening of the tight junctions (TJs) and the anti-invasive activity in human gastric adenocarcinoma AGS cells to elucidate further the possible anticancer mechanisms that G lucidum exerts. Within the concentrations of EGL that were not cytotoxic, EGL markedly inhibited the cell motility and invasiveness in a concentration-dependent manner. The activities of matrix metalloproteinases (MMP)-2 and MMP-9 in AGS cells were dose-dependently inhibited by treatment with EGL, and this was correlated with a decrease in expression of their mRNA and proteins and the upregulation of the expression of the tissue inhibitors of metalloproteinases. The anti-invasive activity of EGL was also found to be associated with the increased tightness of the TJ, which was demonstrated by an increase in transepithelial electrical resistance. Additionally, EGL repressed the levels of the claudin family members, which are major components of TJs that play a key role in the control and selectivity of paracellular transport. Furthermore, the levels of E-cadherin, a type I transmembrane glycoprotein, were inhibited by EGL treatment, however, those of snail, an epithelial to mesenchymal transition regulator and zinc finger transcription factor, were concentration-dependently increased in response to EGL treatment. Although further studies are needed, the present study indicates that TJs and MMPs are crucial targets of EGL-induced anti-invasiveness in human gastric cancer AGS cells.
Journal of acupuncture and meridian studies. 12/2011; 4(4):225-35.
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ABSTRACT: Correlation between inhibition of cell motility and anti-invasive activity by the water extract of HangAmDan-B (HAD-B), a crude extract of eight Korean medicinal animals and plants, in NCI-H460 human non-small cell lung cancer (NSCLC) cells was investigated. Within the concentrations that were not cytotoxic, HAD-B induced significant concentration-dependent inhibition of cell motility and invasiveness of NCI-H460 cells. Treatment with HAD-B resulted in dose-dependent inhibition of the activities of matrix metallo-proteinase (MMP)-2 and MMP-9, and this was correlated with a decrease in expression of their mRNA and proteins, and upregulation of tissue inhibitors of metalloproteinase (TIMP)-1 and TIMP-2 expression. Anti-invasive activity of HAD-B was also found to be associated with increased tightness of the tight junction (TJ), as demonstrated by an increase in transepithelial electrical resistance. In addition, the present results indicated that treatment with HAD-B resulted in repression of the levels of claudin family members, which are major components of TJs that play a key role in control and selectivity of para-cellular transport. Although further studies are needed, findings from the present study indicate that TJs and MMPs are critical targets of HAD-B-induced anti-invasiveness in NCI-H460 NSCLC cells.
Oncology Reports 08/2011; 26(6):1601-8. · 1.84 Impact Factor
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ABSTRACT: Claudins are a family of proteins that are the most important components of the tight junctions. Recently it has been reported that these proteins are overexpressed in cancers and there is a positive correlation between suppression of the expression of these proteins and anti-invasive activity. Matrix metalloproteinases (MMPs) have been implicated as important mediators in cancer invasion. Here, we investigated the effects of anthocyanins on tight junctions (TJs) and the expression of claudins as well as MMPs. The inhibitory effects of the anthocyanins on cell proliferation, motility and invasiveness were found to be associated with tightening TJs, which was demonstrated by an increase in transepithelial electrical resistance (TER). The expression of claudin proteins was suppressed by anthocyanins. Furthermore, the activities of MMP-2 and -9 were dose-dependently suppressed by anthocyanin treatment. These effects were related to activation of 38-MAPK and suppression of the PI3K/Akt pathway in HCT-116 human colon cancer cells.
Oncology Reports 02/2011; 25(2):567-72. · 1.84 Impact Factor
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ABSTRACT: Diallyl disulfide (DADS) is a major component of an oil-soluble allyl sulfide garlic (Allium sativum) derivative, which has been shown to exert a potential for anti-cancer activity. However, the biochemical mechanisms underlying DADS-induced anti-invasiveness and anti-metastasis have not been thoroughly studied. In this study, we investigated the effect of DADS on the correlation between tightening of tight junctions (TJs) and anti-invasive activity in human prostate carcinoma LNCaP cells. Inhibitory effects of DADS on cell motility and invasiveness were found to be associated with increased tightness of the TJ, which was demonstrated by an increase in transepithelial electrical resistance (TER). Additionally, immunoblotting results indicated that DADS repressed the levels of the claudin proteins, which are major components of TJs that play a key role in control and selectivity of paracellular transport. Furthermore, the activities of matrix metalloproteinase (MMP)-2 and -9 in LNCaP cells were dose-dependently inhibited by treatment with DADS, and this was also correlated with a decrease in expression of their mRNA and proteins. Although further studies are needed, the present study indicates that TJs and MMPs are critical targets of DADS-induced anti-invasiveness in human prostate cancer LNCaP cells.
Toxicology in Vitro 09/2010; 24(6):1569-76. · 2.78 Impact Factor
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ABSTRACT: Anthocyanins belong to a class of flavonoids that exhibit important anti-oxidant and anti-inflammatory actions as well as chemotherapeutic effects. However, little is known concerning the molecular mechanisms by which these activities are exerted. In this study, we investigated the anthocyanins isolated from Vitis coignetiae Pulliat for their potential anti-proliferative and apoptotic effects on human colon cancer HCT-116 cells. These anthocyanins inhibited cell viability and induce apoptotic cell death of HCT-116 cells in a dose-dependent manner. The apoptotic cell death was caspase-dependent and the anthocyanins regulated anti-apoptotic proteins (IAPs). In addition, apoptosis was associated with activation of p38-MAPK and suppression of Akt. In conclusion, this study suggests that the anthocyanins isolated from Vitis coignetiae Pulliat induce apoptosis might at least in part through activating p38-MAPK and suppressing Akt in human colon cancer HCT-116 cells.
International Journal of Oncology 12/2009; 35(6):1499-504. · 2.40 Impact Factor
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Dong Yeok Shin,
Won Sup Lee,
Seok Hyun Kim,
Min Jeong Kim,
Jeong Won Yun,
Jing Nan Lu,
Sung Joong Lee,
Irina Tsoy,
Hye Jung Kim,
Chung Ho Ryu,
Gi Young Kim,
Ho Sung Kang,
Sung Chul Shin,
Yung Hyun Choi
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ABSTRACT: We investigated anti-invasive effects of the anthocyanins from fruits of Vitis coignetiae Pulliat (known as meoru in Korea) on human hepatoma Hep3B cells. The anthocyanins inhibited cell invasion in a dose-dependent manner as measured by Matrigel (BD Biosciences, San Jose, CA, USA) invasion assays. They also inhibited expression of matrix metalloproteinase (MMP)-2 and MMP-9 and activation of nuclear factor kappaB (NF-kappaB) stimulated by tumor necrosis factor alpha. Taken together, the results of this study indicate that the anthocyanins isolated from fruits of V. coignetiae Pulliat have anti-invasive effects on human hepatoma Hep3B cells and inhibit MMP-2 and MMP-9 gene expression at least in part through the inhibition of NF-kappaB activation.
Journal of medicinal food 10/2009; 12(5):967-72. · 1.39 Impact Factor
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ABSTRACT: Anthocyanins belong to a class of flavonoids exhibiting antioxidant and anti-inflammatory actions as well as a variety of chemotherapeutic effects. However, little is known about the cellular and molecular mechanism of anticancer activity. In this study, we investigated if the anthocyanins (delphinidin-3,5-diglucoside: cyanidin-3,5-diglucoside: petunidin-3,5-diglucoside: delphinidin-3-glucoside: malvdin-3,5-diglucoside: peonidin-3,5-diglucoside: cyanidin-3-glucoside: petunidin-3-glucoside: peonidin-3- glucoside: malvidin-3- glucoside = 27:63:8.27:1:2.21:2.21:6.7:1.25:5.72:1.25) [corrected] isolated from meoru (Vitis coignetiae Pulliat) exerted antiproliferative and anti-invasive and apoptotic effects on human hepatoma Hep3B cells. It was found that the anthocyanins could inhibit cell growth by 75% at the concentration of 400 microg/mL for 48 h. Flow cytometric analysis showed that the anthocyanins increased the amount of DNA fragments (sub-G1 fraction) in a dose-dependent manner, which is closely related to mitochondrial dysfunction and reduction in antiapoptotic proteins (Bcl-2, xIAP, cIAP-1, and cIAP-2). The anthocyanins also significantly inhibited the migration and invasion of Hep3B cells through a matrigel-coated chamber. Taken together this study indicates that the anthocyanins from meoru have antiproliferative and anti-invasive effects and may induce apoptosis through the activation of the mitochondrial pathway and inhibition of antiapoptotic proteins. This study provides evidence that the anthocyanins isolated from meoru might be useful in the treatment of human hepatitis B-associated hepatoma.
Annals of the New York Academy of Sciences 09/2009; 1171:137-48. · 3.15 Impact Factor
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ABSTRACT: Chan Su is a traditional Chinese medicine prepared from the dried white secretion of the auricular and skin glands of toads, and has been used as an oriental drug for the treatment of a number of diseases, including cancer. In this study, the potential of Chan Su (skin of Venenum Bufonis) to induce apoptosis in human lung carcinoma A549 cells was investigated. Treatment of A549 cells with skin of Venenum Bufonis resulted in the inhibition of cell growth and viability and the induction of apoptosis, which was shown by trypan blue counts, MTT assay, DAPI staining and flow cytometry analysis. The increase in apoptosis that was induced by skin of Venenum Bufonis was correlated with down-regulation of anti-apoptotic Bcl-2 expression, up-regulation of pro-apoptotic Fas ligand and death receptor 4, and a decrease in the mitochondrial membrane potential. Skin of Venenum Bufonis treatment induced the proteolytic activation of caspases and a concomitant degradation of poly(ADP-ribose)-polymerase and beta-catenin protein. Cleavage of Bid and a down-regulation of the inhibitor of apoptosis family proteins were also observed in skin of Venenum Bufonis-treated A549 cells. Data from this study indicates that SVB induces the apoptosis of A549 cells through a signaling cascade of death receptor-mediated extrinsic and mitochondria-mediated intrinsic caspase pathways.
Journal of acupuncture and meridian studies. 09/2009; 2(3):210-7.
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Shin Hwa Lee,
Su Min Park,
Suk Min Park,
Jae Hyeon Park, Dong Yeok Shin,
Gi Young Kim,
Chung Ho Ryu,
Sung Chul Shin,
Jin Myung Jung,
Ho Sung Kang,
Won Sup Lee,
Yung Hyun Choi
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ABSTRACT: Anthocyanins are a class of flavonoids, widely spread throughout the plant kingdom, that exhibit important anti-oxidant and anti-inflammatory actions as well as chemotherapeutic effects. However, little is known concerning the molecular mechanisms by which these activities are exerted. In this study, we investigated the anthocyanins isolated from Vitis coignetiae Pulliat for their potential anti-proliferative and apoptotic effects on human leukemia U937 cells. It was found that these anthocyanins inhibit cell viability and induce apoptotic cell death of U937 cells in a dose-dependent manner, as measured by hemocytometer counts, by alteration in the mitochondrial membrane potential, by increases in sub-G1 populations and by DNA ladder formation. Apoptosis of U937 cells by anthocyanins was associated with modulation of expression of Bcl-2 and IAP family members. Consequently, anthocyanin treatment induced proteolytic activation of caspase-3, -8 and -9, and a concomitant degradation of poly(ADP-ribose) polymerase. However, anthocyanin-induced growth inhibition and apoptosis were significantly attenuated in Bcl-2 overexpressing U937 cells. Furthermore, z-DEVD-fmk, a caspase-3 specific inhibitor, blocked apoptosis and increased the survival of anthocyanin-treated U937 cells. Taken together, these results show that Bcl-2 and caspases are key regulators of apoptosis in response to anthocyanins in human leukemia U937 cells.
International Journal of Oncology 05/2009; 34(4):1077-83. · 2.40 Impact Factor
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ABSTRACT: Streptochlorin is a small molecule isolated from marine Streptomyces sp. that is known to have antiangiogenic and anticancer properties. In this study, we examined the effects of this compound on reactive oxygen species (ROS) production and the association of these effects with apoptotic tumor cell death, using a human hepatocarcinoma Hep3B cell line. The results of this study demonstrated that streptochlorin mediates ROS production, and that this mediation is followed by a decrease in the mitochondrial membrane potential (MMP, m), activation of caspase-3, and downregulation of antiapoptotic Bcl-2 protein. The quenching of ROS generation by N-acetyl-L-cysteine administration, a scavenger of ROS, reversed the streptochlorin-induced apoptosis effects via inhibition of ROS production, MMP collapse, and the subsequent activation of caspase-3. These observations clearly indicate that ROS are involved in the early molecular events in the streptochlorin-induced apoptotic pathway. Taken together, our data imply that streptochlorin-induced ROS is a key mediator of MMP collapse, which leads to the caspase-3 activation, culminating in apoptosis.
Journal of Microbiology and Biotechnology 12/2008; 18(11):1862-8. · 1.38 Impact Factor
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ABSTRACT: Platycodon D is a major constituent of triterpene saponins found in the root of Platycodon grandiflorum, Platycodi Radix, which is widely used in traditional Oriental medicine for the treatment of many chronic inflammatory diseases. The results of previous studies have shown that this compound has in vitro growth-inhibitory activity in human cancer cells, however, the mechanism by which this action occurs is poorly understood. In this study, we examined the effects of platycodon D on the production of reactive oxygen species (ROS) and evaluated the association of these effects with apoptotic tumor cell death using a human leukemic U937 cell line. The results of this study demonstrate that platycodon D mediates ROS production, and that this mediation is followed by a decrease in mitochondrial membrane potential (MMP, DJm), activation of caspase-3, and cleavage of poly (ADP-ribose) polymerase (PARP). Both the cytotoxic effects and apoptotic characteristics induced by platycodon D treatment were significantly inhibited by z-DEVD-fmk, a caspase-3 inhibitor, which demonstrates the important role that caspase-3 plays in the observed cytotoxic effect. Additionally, the transcription factor early growth response-1 (Egr-1) gene was transcriptionally activated and the levels of non-steroidal anti-inflammatory drug (NSAID)-activated gene-1 (NAG-1) protein were elevated in platycodon D-treatedU937 cells. However, the quenching of ROS generation in response to treatment with a ROS scavenger, N-acetyl-L-cysteine, reversed the platycodon D-induced apoptosis effects via inhibition of Egr-1 activation, ROS production, MMP collapse, and the subsequent activation of caspase-3. Although further studies are needed to demonstrate that increased expression of Egr-1 by platycodon D leads directly to NAG-1 induction and subsequent apoptosis, our observations clearly indicate that ROS induced through Egr-1 activation are involved in the early molecular events involved in the platycodon D-induced apoptotic pathway.
Biomedicine & pharmacotherapy = Biomedecine & pharmacotherapie 09/2008; 63(2):86-94. · 2.24 Impact Factor
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ABSTRACT: Platycodin D (PD) is a major constituent of triterpene saponins found in the root of Platycodon grandiflorum. Recent studies have demonstrated that PD is a potentially interesting candidate for use in cancer chemotherapy. However, the molecular mechanisms responsible for PD-induced telomerase inhibition remain to be poorly known. In this study, we examined the effects of PD treatment on telomerase activity in different human leukemia cell lines. At concentrations between 10 and 20 microM, PD exerted a dose-dependent direct cytotoxic effect and inhibition of telomerase activity via downregulation of hTERT expression. Because c-Myc and Sp1 are known to directly regulate transcription of hTERT, we also evaluated the expression and DNA binding activity of these proteins. PD treatment reduced c-Myc and Sp1 protein levels and DNA binding activities in a dose-dependent manner. We also observed that PD treatment downregulates the activation of Akt, thereby reducing the phosphorylation and nuclear translocation of hTERT. We conclude that PD has direct cytotoxic effect on human leukemia cells and suppresses telomerase activity through transcriptional and posttranslational suppression of hTERT.
Cancer Letters 04/2008; 261(1):98-107. · 4.24 Impact Factor
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ABSTRACT: The tumor suppressor protein p53 restricts proliferation in response to DNA damage or the deregulation of mitogenic oncogenes, by leading to the induction of various cell cycle checkpoints, apoptosis or cellular senescence. Consequently, p53 mutations increase cell proliferation and survival and in some settings promote genomic instability and resistance to certain anti-cancer drugs. It is very important to identify chemotherapeutic agents that activate in a p53-independent manner for the development of treatments for p53-deficient tumors. Pectenotoxin-2 (PTX-2), isolated from marine sponges has been reported to display significant cytotoxicity to p53-deficient cancer cell lines. In this study, we compared the anti-cancer activity of PTX-2 in order to further test the status of p53 using two well-known hepatocarcinoma cell lines, p53-deficient Hep3B and p53-wild-type HepG2. MTT assay indicated that Hep3B cells were highly susceptible, whereas HepG2 cells were more resistant to this compound which was connected with the induction of apoptotic cell death in p53-deficient Hep3B cells, though not in HepG2 cells. The apoptosis induced by PTX-2 in Hep3B cells was associated with the down-regulation of anti-apoptotic Bcl-2 members (Bcl-2 and Bcl-xL) and IAP family proteins, the up-regulation of pro-apoptotic Bax protein and tumor necrosis factor-related apoptosis-inducing ligand (TRAIL)-receptor 1/receptor 2 (DR4/DR5) and mitochondrial dysfunction. PTX-2 activated caspases (caspase-3, -8 and -9) and the blockade of caspase-3 activity by the caspase-3 inhibitor prevented the PTX-2-induced apoptosis in Hep3B cells. Additionally, the transcription factor early growth response-1 (Egr-1) gene was transcriptionally activated and the levels of non-steroidal anti-inflammatory drugs (NSAID)-activated gene-1 (NAG-1) protein were also elevated in PTX-2-treated Hep3B cells. Although further studies are needed to prove that an increased expression of Egr-1 by PTX-2 directly leads to NAG-1 induction and then apoptosis induction in p53-deficient Hep3B cells, the results of this study suggest that PTX-2 may be a good candidate for the development of a potential anti-tumorigenic agent in p53-deficient tumors.
Oncology Reports 03/2008; 19(2):517-26. · 1.84 Impact Factor
