Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound   Target Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound

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Query: UMLS:C0019204 (hepatocellular carcinoma)
71,386 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Reactive oxygen species (ROS) have been implicated in the pathogenesis of a variety of diseases, and antioxidant treatment is currently being investigated as a potential therapy to attenuate the detrimental effects of ROS-mediated oxidative stress. Melatonin is a potent naturally produced antioxidant, which acts through various mechanisms to ameliorate the toxic effects of ROS. However, little is known about the mechanisms of signaling pathways through which melatonin acts to reverse the effects of ROS. In the present study, the effect of melatonin treatment on the hydrogen peroxide (H(2)O(2))-induced activation of the mitogen-activated protein kinase (MAPK) and mammalian target of rapamycin (mTOR) signaling pathways was assessed in H4IIE hepatoma cells. It was found that melatonin strongly attenuated H(2)O(2)-induced activation of the ERK1/2 and p38 MAP kinases, as well as several of their downstream targets. Melatonin also attenuated the H(2)O(2)-induced phosphorylation of Akt and the Akt substrate mTOR, as well as a downstream target of mTOR action, 4E-BP1. Upregulation of ERK1/2, p38, and Akt signaling by H(2)O(2) was accompanied by activation of Ras, an effect that was blocked by melatonin. Overall, the results suggest that melatonin acts to prevent many of the H(2)O(2)-induced alterations in the MAPK and mTOR signaling pathways through inhibition of Ras, at least in H4IIE hepatoma cells.
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PMID:Melatonin represses oxidative stress-induced activation of the MAP kinase and mTOR signaling pathways in H4IIE hepatoma cells through inhibition of Ras. 1841 May 86

The purpose of the study was to elucidate the mechanism underlying the enhancement of radiosensitivity to 60Co gamma-irradiation in human hepatoma cell line HepG2 pretreated with gliotoxin. Enhancement of radiotherapy by gliotoxin was investigated in vitro with human hepatoma HepG2 cell line. Apoptosis related proteins were evaluated by Western blotting. Annexin V/PI and reactive oxygen species (ROS) were quantified by Flow Cytometric (FACS) analysis. Gliotoxin (200 ng/ml) combined with radiation (4 Gy) treated cells induced apoptosis. Cells treated with gliotoxin (200 ng/ml) prior to irradiation at 4 Gy induced the expression of bax and nitric oxide (NO). The gliotoxin-irradiated cells also increased caspase-3 activation and ROS. Gadd45a, p38, and nuclear factor kappa B (NFkappaB) activated in irradiated cells was inhibited by Gliotoxin. Specific inhibitors of p38 kinase, SB203580, significantly inhibited NFkappaB activation and increased the cytotoxicity effect in cells exposed to gliotoxin combined with irradiation. However, SB203580 did not suppress the activation of Gadd45a in irradiated cells. Gliotoxin inhibited anti-apoptotic signal pathway involving the activation of Gadd45a-p38-NFkappaB mediated survival pathway that prevent radiation-induced cell death. Therefore, gliotoxin, blocking inflammation pathway and enhancing irradiation-induced apoptosis, is a promising agent to increase the radiotherapy of tumor cells.
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PMID:Gliotoxin enhances radiotherapy via inhibition of radiation-induced GADD45a, p38, and NFkappaB activation. 1842 44

Benzyl isothiocyanate (BITC) is a hydrolysis compound of glucotropaeolin in cruciferous vegetables. Many studies have reported that BITC prevents cancers in laboratory animals and might also be chemoprotective in humans. The purpose of this study was to investigate the effects of BITC on cell proliferation, metastasis, and MAPK pathways of SK-Hep1 human hepatocellular carcinoma cells. BITC suppressed SK-Hep1 cell proliferation in a dose-dependent manner, and exposure to 1 and 5 microM BITC reduced cell proliferation by 25% and 30%, respectively. The expression of matrix metalloproteinase (MMP)-2, MMP-9, and membrane type-1/MMP (MT-1/MMP) is a known risk factor for metastatic disease. Gelatin zymography analysis revealed a significant downregulation of MMP-2/-9 protein expression in SK-Hep1 cells treated with 0.1-5 microM BITC. BITC treatment caused dose-dependent decreases in MMP-2/-9 and MT1-MMP mRNA levels as determined by RT-PCR. BITC also increased the mRNA levels of tissue inhibitors of matrix metalloproteinases-2 (TIMP-2) 1.3- and 1.5-fold after a 24 h exposure to 1 and 5 microM BITC, respectively. Increased TIMP-2 expression is mediated by the downregulation of MMP-2 and MT1-MMP. BITC inhibited the phosphorylation activities of all three major mitogen-activated protein kinases (MAPKs) in a dose-dependent manner. BITC at 5 microM reduced the ERK1/2 phosphorylation activity by 50% and p38 activity by 70%. BITC also reduced the p-JNK1/2 level by 30% and 70% at 1 and 5 microM treatments, respectively. These data may represent anti-metastatic activities of BITC through the suppression of MAPKs in SK-Hep1 cells.
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PMID:Benzyl isothiocyanate inhibits metalloproteinase-2/-9 expression by suppressing the mitogen-activated protein kinase in SK-Hep1 human hepatoma cells. 1850 15

A newly synthesized dithiocarbamate derivative, 4-methylpiperazine-1-carbodithioc-acid-3-cyano-3,3-diphenylpropyl ester hydrochloride (TM208), has demonstrated anticancer effects with low toxicity in earlier studies; however, the mechanism has yet to be identified. We explored antitumor effects of TM208 and the possible mechanisms by which it inhibited the growth of human hepatocellular carcinoma cell line QGY-7703 xenograft tumors. Cell proliferation was evaluated with the sulforhodamine B assay in vitro. The results suggested that TM208 had slightly antiproliferative activity on QGY-7703 cells. The antitumor effect of TM208 was assessed in nude mice xenografted with QGY-7703 tumors. We found that TM208 significantly inhibited tumor growth but did not cause loss of body weight or leukocytopenia. Western blotting was used to detect the expression of protein kinase C alpha, mitogen-activated protein kinase signal pathways, and cell cycle-related proteins. The results showed that TM208 decreased the expression of protein kinase C alpha, phospho-extracellular signal-regulated kinase-1/2, phospho-p38, cyclin B1, cell division cycle 2 (cdc2), and phospho-cdc2 (Thr161) and increased the expression of phospho-cdc2 (Tyr15). Taken together, our data show that TM208 has little antiproliferative effect on QGY-7703 cells in vitro, whereas it significantly inhibits the growth of QGY-7703 xenograft tumors with low toxicity in vivo. The inhibition of mitogen-activated protein kinase signal pathways and the regulation of the G2/M phase may be responsible for its antitumor effects.
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PMID:Effect of TM208 on QGY-7703 xenograft tumor growth. 1852 18

Our previous study indicated that oleic acid prevented apoptotic cell death induced by trans10, cis12 (t10, c12)-conjugated linoleic acid in rat hepatoma dRLh-84 cells. The intracellular mechanism of action oleic acid is still unknown. Here, we showed that p38 mitogen-activated protein kinase (MAPK) inhibition using its specific inhibitor SB203580 cancelled the ameliorative effect of oleic acid on the cytotoxicity of t10, c12-conjugated linoleic acid. In addition, SubG1 cell population analysis showed that p38 MAPK played an essential role in the prevention of apoptotic cell death by oleic acid. In fact, p38 phosphorylation level was upregulated in cells treated with oleic acid irrespective of t10, c12-conjugated linoleic acid stimulation. Interestingly, t10, c12-conjugated linoleic acid increased intracellular triglyceride accumulation. However, oleic acid completely inhibited this effect. These observations indicated the involvement of blockade of a p38 MAPK pathway in the ameliorative effect of oleic acid on apoptosis induced by t10, c12-conjugated linoleic acid.
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PMID:Oleic acid prevents apoptotic cell death induced by trans10, cis12 isomer of conjugated linoleic acid via p38 MAP kinase dependent pathway. 1856 73

Oridonin, a diterpenoid isolated from Rabdosia rubescences, could induce apoptosis through the generation of reactive oxygen species (ROS) in human hepatoma HepG2 cells. p53, a specific inhibitor of pifithrin alpha (PFT alpha), markedly inhibited ROS generation and apoptosis, showing that p53 was responsible for the cytotoxity of oridonin through mediation by ROS. Moreover, the ROS activated the p38 kinase, which in turn promoted the activation of p53, as verified by evidence showing that the ROS scavenger N-acetyl-cysteine (NAC) not only blocked the phosphorylation of p38 but also partially inhibited the activation of p53, and the p38 inhibitor SB203580 reduced the activation of p53 as well. Mitochondria were either the sources or the targets of ROS. This study showed that oridonin stimulated mitochondrial transmembrane permeabilization in a ROS-dependent manner because NAC almost thoroughly reversed the drop of mitochondrial transmembrane potential (Deltapsim) and the release of cytochrome c from the mitochondrial inter-membrane space into cytosol. Furthermore, as a result of mitochondrial permeability transition, procaspases-9 and -3 were cleaved into 37- and 17-kDa proteolytic products, respectively, which acted as executors of oridonin-induced apoptosis.
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PMID:Reactive oxygen species mediate oridonin-induced HepG2 apoptosis through p53, MAPK, and mitochondrial signaling pathways. 1871 15

Hepatitis C virus often causes persistent infection and hepatocellular carcinoma. Studies have demonstrated the roles of viral nonstructural protein 5A (NS5A) in the induction of chromosome aneuploidy, but the molecular mechanisms are not clear. In this study, hydrodynamics-based in vivo transfection was applied to a mouse system. Mouse hepatocytes that successfully expressed NS5A protein were isolated by laser capture microdissection. Gene expression profiles of the NS5A-expressing hepatocytes were examined by an Affymetrix oligonucleotide microarray system. Aspm (abnormal spindle-like, microcephaly associated), which encodes the mitotic spindle protein ASPM, was identified to be differentially expressed in the absence and the presence of NS5A. The down-regulation of Aspm mRNA and ASPM protein was confirmed by real time polymerase chain reaction and Western blot analysis, respectively, both in mouse model systems and in viral subgenomic replicon and in vitro transfection culturing systems. In addition, cultured cells that constitutively expressed NS5A protein showed G(2)/M cell cycle block and chromosome aneuploidy. Overexpression of ASPM relieved the G(2)/M cell cycle block. Furthermore, NS5A protein repressed the promoter activity of Aspm gene in a dose-dependent manner. The regulatory effect was abolished when amino acid substitutions P2209L, T2214A, and T2217G known to interrupt the NS5A-PKR interaction were introduced into the NS5A protein. This indicates that the down-regulation of Aspm expression is via the PKR-p38 signaling pathway. These results suggest that NS5A protein down-regulates the expression of the mitotic spindle protein ASPM and induces aberrant mitotic cell cycle associated with chromosome instability and hepatocellular carcinoma.
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PMID:Hepatitis C virus NS5A protein down-regulates the expression of spindle gene Aspm through PKR-p38 signaling pathway. 1872 14

Prior studies have noted that inhibitors of mitogen-activated protein kinase (MAPK) kinase 1/2 (MEK1/2) enhanced geldanamycin lethality in malignant hematopoietic cells by promoting mitochondrial dysfunction. The present studies focused on defining the mechanism(s) by which these agents altered survival in carcinoma cells. MEK1/2 inhibitors [PD184352; AZD6244 (ARRY-142886)] interacted in a synergistic manner with geldanamycins [17-allylamino-17-demethoxygeldanamycin (17AAG) and 17-dimethylaminoethylamino-17-demethoxy-geldanamycin] to kill hepatoma and pancreatic carcinoma cells that correlated with inactivation of extracellular signal-regulated kinase 1/2 and AKT and with activation of p38 MAPK; p38 MAPK activation was reactive oxygen species dependent. Treatment of cells with MEK1/2 inhibitors and 17AAG reduced expression of c-FLIP-s that was mechanistically connected to loss of MEK1/2 and AKT function; inhibition of caspase-8 or overexpression of c-FLIP-s abolished cell killing by MEK1/2 inhibitors and 17AAG. Treatment of cells with MEK1/2 inhibitors and 17AAG caused a p38 MAPK-dependent plasma membrane clustering of CD95 without altering the levels or cleavage of FAS ligand. In parallel, treatment of cells with MEK1/2 inhibitors and 17AAG caused a p38 MAPK-dependent association of caspase-8 with CD95. Inhibition of p38 MAPK or knockdown of BID, FAS-associated death domain, or CD95 expression suppressed MEK1/2 inhibitor and 17AAG lethality. Similar correlative data were obtained using a xenograft flank tumor model system. Our data show that treatment of tumor cells with MEK1/2 inhibitors and 17AAG induces activation of the extrinsic pathway and that suppression of c-FLIP-s expression is [Mol Cancer Ther 2008;7(9):2633-48].
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PMID:Mitogen-activated protein kinase kinase 1/2 inhibitors and 17-allylamino-17-demethoxygeldanamycin synergize to kill human gastrointestinal tumor cells in vitro via suppression of c-FLIP-s levels and activation of CD95. 1879 Jul 46

Oncoprotein p28GANK knockdown by RNA interference (RNAi) can induce hepatoma cells apoptosis. However, the mechanisms have not been well defined yet. In the present study the p28GANK knockdown-induced apoptosis in HepG2 cells was prevented by caspase-9 inhibitor (Z-LEHD-FMK). During the knockdown of p28GANK, mitochondrial translocation of Bax, loss of mitochondrial transmembrane potential (DeltaPsim) and release of cytochrome c were observed. In this study, the activation of p38 was found to be critical for the p28GANK knockdown-induced apoptosis, as suggested by the finding that pharmacological inhibition of p38 with SB203580 suppressed the redistribution of Bax, the loss of DeltaPsim and the apoptosis. Moreover, generation of reactive oxygen species (ROS) contributed to the cell death because N-acetyl-L-cystenine (NAC), a ROS scavenger, suppressed the phosphorylation of p38 and the apoptosis. Our studies established the signaling pathway of p28GANK knockdown-induced apoptosis in HepG2 cells, namely, mitochondrial dysfunction mediated by p38 downstream of intracellular ROS generation.
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PMID:p28GANK knockdown-derived reactive oxygen species induces apoptosis through mitochondrial dysfunction mediated by p38 in HepG2 cells. 1881 87

Melatonin reduces proliferation in many different cancer cell lines. However, studies on the oncostatic effects of melatonin in the treatment of hepatocarcinoma are limited. In this study, we examined the effect of melatonin administration on HepG2 human hepatocarcinoma cells, analyzing cell cycle arrest, apoptosis and mitogen-activated protein kinase (MAPK) signalling pathways. Melatonin was dissolved in the cell culture media in 0.2% dimethyl sulfoxide and administered at different concentrations for 2, 4, 6, 8 and 10 days. Melatonin at concentrations 1000-10,000 microM caused a dose- and time-dependent reduction in cell number. Furthermore, melatonin treatment induced apoptosis with increased caspase-3 activity and poly(ADP-ribose) polymerase proteolysis. Proapoptotic effects of melatonin were related to cytosolic cytochrome c release, upregulation of Bax and induction of caspase-9 activity. Melatonin treatment also resulted in increased caspase-8 activity, although no significant change was observed in Fas-L expression. In addition, JNK 1,-2 and -3 and p38, members of the MAPK family, were upregulated by melatonin treatment. Growth inhibition by melatonin altered the percentage or cells in G0-G1 and G2/M phases indicating cell cycle arrest in the G2/M phase. The reduced cell proliferation and alterations of cell cycle were coincident with a significant increase in the expression of p53 and p21 proteins. These novel findings show that melatonin, by inducing cell death and cell cycle arrest, might be useful as adjuvant in hepatocarcinoma therapy.
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PMID:Melatonin induces cell cycle arrest and apoptosis in hepatocarcinoma HepG2 cell line. 1901 62


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