• The Korean Journal of Physiology and Pharmacology
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• v.6 no.4
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• pp.187-191
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• 2002

Tamoxifen, an antiestrogen, has previously been shown to induce apoptosis in HepG2 human hepatoblastoma cells through activation of the pathways independent of estrogen receptors, i.e., intracellular $Ca^{2+}$ increase and generation of reactive oxygen species (ROS). However, the mechanism of tamoxifen to link increased intracellular $Ca^{2+}$ to ROS generation is currently unknown. Thus, in this study we investigated the possible involvement of calmodulin, a $Ca^{2+}$ activated protein, and $Ca^{2+}$/calmodulin-dependent protein kinase II in the above tamoxifen-induced events. Treatment with calmodulin antagonists (calmidazolium and trifluoroperazine) or specific inhibitors of $Ca^{2+}$/calmodulin-dependent protein kinase II (KN-93 and KN-62) inhibited the tamoxifen-induced apoptosis in a dose-dependent manner. In addition, these agents blocked the tamoxifen-induced ROS generation in a concentration-dependent fashion, which was completely suppressed by intracellular $Ca^{2+}$ chelation. These results demonstrate for the first time that, despite of its well-known direct calmodulin-inhibitory activity, tamoxifen may generate ROS and induce apoptosis through indirect activation of calmodulin and $Ca^{2+}$/calmodulin-dependent protein kinase II in HepG2 cells.

• Korean Journal of Veterinary Service
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• v.22 no.2
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• pp.135-149
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• 1999

This study was concerned with assessment of dietynitrosamine (DEN) induced liver cell carcinogenesis by measurement of changes preceding the development of neoplasms. The changes of hepatic morphology in rats(Sprague-Dawley) were detected by hematoxylin-eosin stain and immunohistochemistry(PCNA). The results were as follows ; 1. Minor behavioral change, brittleness of hair and decreased amount of water and diet intake. were observed in rats 7 weeks after DEN administration. 2. Variable size of liver tumor and hepatomegaly were observed in rats treated with DEN after 10 weeks. 3. Numerous vacuoles were showed on the midzonal and or peripheral areas of hepatic lobules. The large and polymorphological hepatocytes with eosinophilic cytoplasm or densely basophilic mitotic nucleoli were showed. 4. Several proliferative small round cells were shown on vacuolated and necrotic areas in peripheral hepatic lobules or portal areas. 5. PCNA-positive cells were showed on the vacuolated portal areas and peripheral areas of hepatic lobules. Maximal positivity was 23.6% in the areas of small round cells. In conclusion, this result confirmed that the DEN was one of the potent hepatocarcinogens. In histopathological analysis, the altered foci, hyperplastic nodules, neoplastic nodules, adenomas and carcinomas were observed in liver tumors induced by administration of DEN in rats.

• Journal of Microbiology and Biotechnology
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• v.26 no.2
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• pp.402-407
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• 2016

Lactic acid bacteria have been identified to be effective in reducing cholesterol levels. Most of the mechanistic studies were focused on the bile salt deconjugation ability of bile salt hydrolase in lactic acid bacteria. However, the mechanism by which Lactobacillus decreases cholesterol levels has not been thoroughly studied in intact primate cells. 3-Hydroxy-3-methyl-glutaryl-coenzyme A reductase (HMGCR) is the vital enzyme in cholesterol synthesis. To confirm the effect of probiotic Lactobacillus strains on HMGCR level, in the present study, human hepatoma HepG2 cells were treated with Lactobacillus strains, and then the HMGCR level was illustrated by luciferase reporter assay and RT-PCR. The results showed that the level of HMGCR was suppressed after being treated with the live Lactobacillus strains. These works might set a foundation for the following study of the antihyperlipidemic effects of L. acidophilus, and contribute to the development of functional foods or drugs that benefit patients suffering from hyperlipidemia diseases.

• Nuclear Medicine and Molecular Imaging
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• v.41 no.3
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• pp.226-233
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• 2007

Purpose: Dual reporter gene imaging has several advantages for more sophisticated molecular imaging studies such as gene therapy monitoring. Herein, we have constructed hepatoma cell line expressing dual reporter genes of sodium iodide symporter (NIS) and enhanced green fluorescence protein (EGFP), and the functionalities of the genes were evaluated in vivo by nuclear and optical imaging. Materials and Methods: A pRetro-PN vector was constructed after separating NIS gene from pcDNA-NIS. RSV-EGFP-WPRE fragment separated from pLNRGW was cloned into pRetro-PN vector. The final vector expressing dual reporter genes was named pRetro-PNRGW. A human hepatoma (HepG2) cells were transfected by the retrovirus containing NIS and EGFP gene (HepG2-NE). Expression of NIS gene was confirmed by RT-PCR, radioiodine uptake and efflux studies. Expression of EGFP was confirmed by RT-PCR and fluorescence microscope. The HepG2 and HepG2-NE cells were implanted in shoulder and hindlimb of nude mice, then fluorescence image, gamma camera image and I-124 microPET image were undertaken. Results: The HepG2-NE cell was successfully constructed. RT-PCR showed NIS and EGFP mRNA expression. About 50% of cells showed fluorescence. The iodine uptake of NIS-expressed cells was about 9 times higher than control. In efflux study, $T_{1/2}$ of HepG2-NE cells was 9 min. HepG2-NE xenograft showed high signal-to-background fluorescent spots and higher iodine-uptake compared to those of HepG2 xenograft. Conclusion: A hepatoma cell line expressing NIS and EGFP dual reporter genes was successfully constructed and could be used as a potential either by therapeutic gene or imaging reporter gene.

• The Korean Journal of Physiology and Pharmacology
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• v.12 no.4
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• pp.143-148
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• 2008

Caveolin-1 (CAV1) is an integral membrane protein that may function as a scaffold for plasma membrane proteins and acts as a tumor suppressor protein. One causative factor of chemotherapy-resistant cancers is P-plycoprotein (P-gp), the product of the multidrug resistance-1 gene (MDR1), which is localized in the caveolar structure. Currently, the interactive roles of CAV1 and MDR1 expression in the death of cancer cells remain controversial. In this study, we investigated the effects of indomethacin on the cell viability and the expression levels of MDR1 mRNA and protein in a CAV1-siRNA-mediated gene knockdown hepatoma cell line (SK-Hep1). Cell viability was significantly decreased in CAV1-siRNA-transfected cells compared with that of control-siRNA-transfected cells. Furthermore, the viability of cells pretreated with CAV1 siRNA was markedly decreased by treatment with indomethacin (400${\mu}$M for 24 h). However, the protein and mRNA levels of MDR1 were unchanged in CAV1-siRNA-transfected cells. These results suggest that CAV1 plays an important role as a major survival enzyme in cancer cells, and indomethacin can sensitively induce cell death under conditions of reduced CAV1 expression, independent of MDR1 expression.

• Journal of Microbiology and Biotechnology
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• v.27 no.7
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• pp.1249-1256
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• 2017

In our search for new sources of bioactive secondary metabolites from Streptomyces sp., the ethyl acetate extracts from endophytic Streptomyces SUK 25 afforded five active diketopiperazine (DKP) compounds. The aim of this study was to characterize the bioactive compounds isolated from endophytic Streptomyces SUK 25 and evaluate their bioactivity against multiple drug resistance (MDR) bacteria such as Enterococcus raffinosus, Staphylococcus aureus, Klebsiella pneumoniae, Acinetobacter baumanii, Pseudomonas aeruginosa, and Enterobacter spp., and their cytotoxic activities against the human hepatoma (HepaRG) cell line. The production of secondary metabolites by this strain was optimized through Thornton's medium. Isolation, purification, and identification of the bioactive compounds were carried out using high-performance liquid chromatography, high-resolution mass liquid chromatography-mass spectrometry, Fourier transform infrared spectroscopy, and nuclear magnetic resonance, and cryopreserved HepaRG cells were selected to test the cytotoxicity. The results showed that endophytic Streptomyces SUK 25 produces four active DKP compounds and an acetamide derivative, which were elucidated as $cyclo-({\text\tiny{L}}-Val-{\text\tiny{L}}-Pro)$, $cyclo-({\text\tiny{L}}-Leu-{\text\tiny{L}}-Pro)$, $cyclo-({\text\tiny{L}}-Phe-{\text\tiny{L}}-Pro)$, $cyclo-({\text\tiny{L}}-Val-{\text\tiny{L}}-Phe)$, and N-(7-hydroxy-6-methyl-octyl)-acetamide. These active compounds exhibited activity against methicillin-resistant S. aureus ATCC 43300 and Enterococcus raffinosus, with low toxicity against human hepatoma HepaRG cells. Endophytic Streptomyces SUK 25 has the ability to produce DKP derivatives biologically active against some MDR bacteria with relatively low toxicity against HepaRG cells line.

• Proceedings of the Ginseng society Conference
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• 1998.06a
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• pp.231-243
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• 1998

In the present study, we provide evidence that ginsenoside $Rh_2$ (G-$Rh_2$) as well as staurosporine induces apoptosis of human hepatoma SK-HEP-1 cells by caspase 3-mediated processing of $p21^{WAFI/CIPI}$ in the early stage of apoptosls. Immunoblottings showed that G-$Rh_2$ as well as statrosporine induced the processing of caspase-3 to an active form, pl7. In stable Bcl-2 transfectants however, G-$Rh_2$ induced DNA fragmentation, while staurosporine did not. In the early stage of apoptosis, $p21^{WAFI/CIPI}$ was detected to undergo proteolytic processing specifically conducted by caspase-3. $p21^{WAFI/CIPI}$ translated in vitro was cleaved into a p14 fragment, when incubated with cell extracts obtained from either G-$Rh_2$- or staurosporine-treated cells. Cleavage was equally inhibited in both cases by adding Ac-DEVD-cho, a specific caspase-3 inhibitor, but not by Ac-YVkD-cho, a specific caspase-l inhibitor. Similarly, $p21^{WAFI/CIPI}$ was efficiently leaved by recombinant caspase-3 overexpressed in E. coli. Moreover, the endogenous $p21^{WAFI/CIPI}$ of untreated-cell extracts was also cleaved by recombinant caspase-3. Mutation analysis allowed identification of two caspase-3 cleavage sites, $DHVD^{112}$/L and $SMTD^{149}$/F, which are located within, or near the interaction domains for cyclins, Cdks, and PCNA. Taken together, these results show that G-$Rh_2$ as well as staurosporine increases caspase-3 activity, which in turn directly cleaves $p21^{WAFI/CIPI}$ resulting in elevation of Cdk kinase activity in the early stages of apoptosis. We propose that proteolytic cleavage of $p21^{WAFI/CIPI}$ is a functionally relevant event that allows unleashing the cyclin/Cdk activity from the inhibitor seen in the earlier stage of apoptosis, the event of which may be associated with the triggering mechanism for the execution of apoptosis.

• Korean Journal of Food Science and Technology
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• v.37 no.2
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• pp.261-267
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• 2005

Phase II enzymes are transcriptionally induced by synthetic chemical agents and natural products, and such induction plays critical roles in protection against chemical carcinogens and other toxic xenobiotics. To discover natural products for use as cancer chemopreventive agents, the ability of Citrus aurantium Linn (Jikak) to induce activities of quinone reductase (QR) and glutathione S-transferase (GST) in wild-type murine hepatoma cell line (Hepa 1c1c7) and Ah-receptor-defective mutant of the same cell line (Bprcl) was investigated. Hexane and chloroform fractions of C. aurantium Linn (Jikak) at doses not exhibiting cytotoxicity were effective inducers of QR (${\sim}1.8-fold$) and GST (${\sim}1.5-fold$) in Hepa 1c1c7 cells, whereas showed low QR induction potency in Bprcl cells, which indicates they have weak monofunctional action. Results suggest C. aurantium Linn (Jikak) as potentially useful cancer chemopteventive agent.

• Journal of Physiology & Pathology in Korean Medicine
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• v.22 no.4
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• pp.821-828
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• 2008

Onchungeum, a herbal formula, which has been used for treatment of anemia due to bleeding, discharging blood and skin disease. In the present study, it was examined the effects of extract of Onchungeum (OCE) on the growth of human hepatocarcinoma cell lines Hep3B (p53 null type) and HepG2 (p53 wild type) in order to investigate the anti-proliferative mechanism by OCE. Treatment of Hep3B and HepG2 cells to OCE resulted in the growth inhibition in a dose-dependent manner, however Hep3B cell line exhibited a relatively strong anti-proliferative activity to OEC. Flow cytometric analysis revealed that OCE treatment in Hep3B cells caused G1 phase arrest of the cell cycle, which was associated with various morphological changes in a dose-dependent fashion. RT-PCR and immunoblotting data revealed that treatment of OCE caused the down-regulation of cyclin D1 expression, however the levels of cyclin E expression were not changed by OCE. The G1 arrest of the cell cycle was also associated with the induction of Cdk inhibitor p27 by OCE. Because the p53 gene is null in Hep3B cells, it is most likely that the induction of p21 is mediated through a p53-independent pathway. Moreover, p27 detected in anti-Cdk4 and anti-Cdk2 immunoprecipitates from the OCE-treated cells, suggesting that OCE-induced p27 protein blocks Cdk kinase activities by directing binding to the cyclin/Cdk complexes. Furthermore, OCE treatment potently suppresses the phosphorylation of retinoblastoma proteins and the levels of the transcription factor E2F-1 expression. Taken together, these results indicated that the growth inhibitory effect of OCE in Hep3B hepatoma cells was associated with the induction of G1 arrest of the cell cycle through regulation of several major growth regulatory gene products.

• Asian Pacific Journal of Cancer Prevention
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• v.15 no.17
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• pp.7043-7048
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• 2014

Inhibition of heat shock protein 90 (Hsp90) leads to inappropriate processing of proteins involved in DNA damage repair pathways after DNA damage and may enhance tumor cell radio- and chemotherapy sensitivity. To investigate the potentiation of antitumor efficacy of lidamycin (LDM), an enediyne agent by the Hsp90 inhibitorgeldanamycin (GDM), and possible mechanisms, we have determined effects on ovarian cancer SKOV-3, hepatoma Bel-7402 and HepG2 cells by MTT assay, apoptosis assay, and cell cycle analysis. DNA damage was investigated with H2AX C-terminal phosphorylation (${\gamma}H2AX$) assays. We found that GDM synergistically sensitized SKOV-3 and Bel-7402 cells to the enediyne LDM, and this was accompanied by increased apoptosis. GDM pretreatment resulted in a greater LDM-induced DNA damage and reduced DNA repair as compared with LDM alone. However, in HepG2 cells GDM did not show significant sensitizing effects both in MTT assay and in DNA damage repair. Abrogation of LDM-induced $G_2/M$ arrest by GDM was found in SKOV-3 but not in HepG2 cells. Furthermore, the expression of ATM, related to DNA damage repair responses, was also decreased by GDM in SKOV-3 and Bel-7402 cells but not in HepG2 cells. These results demonstrate that Hsp90 inhibitors may potentiate the antitumor efficacy of LDM, possibly by reducing the repair of LDM-induced DNA damage.