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)

To investigate the contribution of apoptosis, a major mechanism of cell death, in the growth of hepatocellular carcinoma, we analyzed both apoptosis and cell proliferation in human hepatocellular carcinoma. We used the terminal deoxynucleotidyl transferase-mediated dUTP-biotin nick end labeling method and proliferative cell nuclear antigen staining, respectively. Among 21 hepatocellular carcinoma specimens examined, four were well, ten were moderately, and seven were poorly differentiated hepatocellular carcinoma. Terminal deoxynucleotidyl transferase-mediated dUTP-biotin nick end labeling-positive cells in hepatocellular carcinoma were scattered individually or were sometimes clustered in the tumors. The terminal deoxynucleotidyl transferase-mediated dUTP-biotin nick end labeling indices were 0.35 +/- 0.09, 0.81 +/- 0.29, and 1.9 +/- 0.94 in well, moderately, and poorly differentiated hepatocellular carcinoma, respectively. The proliferative cell nuclear antigen labeling indices were 6.6 +/- 0.9, 13.1 +/- 3.5, and 26.7 +/- 6.3 in hepatocellular carcinoma in the same respective order of differentiation. The differences in both terminal deoxynucleotidyl transferase-mediated dUTP-biotin nick end labelling indices and proliferative cell nuclear antigen labeling indices (p < 0.05) were significant between well, moderately and poorly differentiated hepatocellular carcinoma. There was a positive correlation between the terminal deoxynucleotidyl transferase-mediated dUTP-biotin nick end labeling and proliferative cell nuclear antigen labeling indices in hepatocellular carcinoma (r = 0.84, p < 0.001). This study showed that the proliferation rate and the incidence of apoptosis increased as the differentiation grade of hepatocellular carcinoma was lowered, suggesting a rapid turnover of cancer cells in the lower differentiation grades. Apoptosis may thus play an important role in the growth of hepatocellular carcinoma.
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PMID:Apoptosis and proliferation of human hepatocellular carcinoma. 874 Aug 46

The detergent Triton X-100 was used to establish a model for apoptosis in hepatoma cell lines. The electrophoresis of DNA extracted from 0.01% Triton X-100 treated hepatoma cell lines showed DNA ladder formation, a hallmark of apoptosis. The DNA fragmentation appeared within less than 60 min of the Triton X-100 treatment. Chromatin condensation and apoptotic bodies were observed by hematoxylin and eosin (H & E) stain, and fragmented nucleosome was detected by terminal deoxynucleotidyl transferase-mediated dUTP-biotin nick end labelling (TUNEL) test. Apoptosis was semi-quantitated by measuring the lactate dehydrogenase (LDH) level for cytotoxity. It was found that apoptosis had been induced in more than 90% of the cells treated with Triton X-100 for 150 min. These data show that Triton X-100 efficiently induces the apoptotic cell death in hepatoma cell lines.
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PMID:Triton X-100 induces apoptosis in human hepatoma cell lines. 910 Apr 83

Although a variety of methods has been devised for modification of hepatic genes, none has been effective for long-term correction of genetic disorders. In this study, we employed a recently described novel experimental strategy for site-directed nucleotide exchange in genomic DNA of HuH-7 human hepatoma cells. A chimeric 2'-O-methylated-RNA/DNA oligonucleotide containing sequences complementary to 25 bases of the alkaline phosphatase gene was constructed as a duplex containing a G to A substitution at nucleotide 935. Cells were transfected with oligonucleotides for 48 hours, then harvested for DNA isolation and polymerase chain reaction (PCR) amplification of exon 6 of the alkaline phosphatase gene. Colony lifts were hybridized to 17 mer 32P-labeled oligonucleotide probes specific to the 935-G and 935-A sequences. Hybridizing colonies were grown, plasmid DNA isolated, and sequenced. Transfection efficiency was determined at 24 hours by nuclear uptake of fluorescein-12-dUTP-labeled chimeric oligonucleotides. Colonies hybridizing with the 935-A probe were identified only from cells transfected with the specific chimeric oligonucleotide; and there was no evidence of cross-hybridization. Conversion of G to A at nucleotide 935 occurred at an overall frequency of up to 11.9% and when corrected for transfection efficiency approached 43%. No other alterations were detected in the sequence of exon 6 with the targeted nucleotide exchange. These results show that a single base pair alteration in the alkaline phosphatase gene of HuH-7 cells can be introduced at a relatively high frequency following transfection with chimeric RNA/DNA oligonucleotides. This technique offers a novel and potentially powerful strategy for site-directed hepatic gene alteration without the use of viral-based vectors.
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PMID:Targeted nucleotide exchange in the alkaline phosphatase gene of HuH-7 cells mediated by a chimeric RNA/DNA oligonucleotide. 918 69

Prolonged infection of hepatitis B virus (HBV) is reported to cause hepatocellular carcinoma (HCC) via liver cirrhosis. However, it is still unknown whether the HCC is induced by the HBV DNA integration or by inflammatory stimulation during the phase of liver cirrhosis. The aim of this study is to determine the intracellular or intranuclear distribution of HBV DNA with a highly sensitive assay. Here we directly detected the integration of HBV DNA by fluorescence in situ polymerase chain reaction (FISPCR). Since FISPCR products directly incorporate rhodamine-4-dUTP, the nucleus of Alexander cells integrated with HBV gene reacted with the HBV primers emits obvious fluorescence. The fluorescence values which were measured with an imaging analyzer show a significant difference between Alexander cells as compared to the controls. In conclusion, the target sequences of HBV were specifically amplified as fluorescent DNA after the present FISPCR procedure. This method could provide a novel and simple strategy for determining the quantitative role of viral DNA integration in oncogenesis.
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PMID:Direct detection of hepatitis B virus gene integrated in the Alexander cell using fluorescence in situ polymerase chain reaction. 921 72

Apoptosis is a morphologically and biochemically distinct form of cell death which can be triggered by a variety of extracellular agents both during normal developments and in adult pathological states. However, the molecular mechanism of apoptotic cell death due to hypoxia has not been clearly elucidated. In this study, we investigated critical factors involved in hypoxia-induced apoptosis using HepG2, a human hepatocellular carcinoma cell line, as an experimental model. We found that 24 h of exposure of HepG2 cells to hypoxia induced apoptosis, for which de novo protein synthesis was required. Apoptosis was demonstrated by DNA fragmentation and terminal deoxynucleotidyl transferase-mediated dUTP nick end labeling (TUNEL) assay. Hypoxia-induced apoptosis was associated with a marked induction of c-jun and c-fos messenger RNAs. Electromobility shift assay showed the increased DNA binding activity of AP-1 during hypoxia, suggesting that AP-1 may be involved in the induction of cell death by acting as a transcriptional regulator. A purine analogue, 6-thioguanine (6-TG), significantly blocked the induction of apoptosis by hypoxia. Moreover, the inductive effect of hypoxia on c-jun expression was also inhibited by 6-TG, whereas the levels of c-fos mRNA and its protein were rather strongly increased. Iodoacetamide (IAA), a non-specific inhibitor of ICE family proteases, also has an inhibitory effect on hypoxia-induced apoptosis. These results suggest that the 6-TG-sensitive protein kinase(s)-dependent signaling pathway may be involved in the apoptotic response of HepG2 cells exposed to hypoxia by increasing the level of c-jun and c-fos and the activity of AP-1 and/or by activating ICE family protease(s).
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PMID:Hypoxia-induced apoptosis in human hepatocellular carcinoma cells: a possible involvement of the 6-TG-sensitive protein kinase(s)-dependent signaling pathway. 956 54

In the AH-130 hepatoma, a poorly differentiated tumor, maintained by weekly transplantations in rats, a low percentage of cells spontaneously underwent apoptosis, mainly during the transition from logarithmic- to stationary-growth phase. It was possible to induce massive apoptosis of cells by treating them with clofibrate, a peroxisome proliferator and hypolipidemic drug. Similar results were obtained with HepG2 cells. With 1 mM clofibrate, apoptosis began to manifest itself after 1 h of treatment in vitro, and was assessed by morphological analysis, by DNA fragmentation carried out with agarose gel electrophoresis, and with flow cytometric determination of terminal deoxynucleotidyl transferase-mediated dUTP-biotin nick end-labeling. The mechanisms whereby clofibrate induces apoptosis are still unclear. Since the peroxisome proliferator-activated receptor was expressed at a very low level and was not stimulated by clofibrate in the AH-130 hepatoma cells, its involvement seems unlikely. Moreover, lipid peroxidation was not increased after clofibrate treatment. Phospholipids and cholesterol were significantly decreased. The decreased cholesterol content might suggest an inhibition of the mevalonate pathway and, therefore, of isoprenylation of proteins involved in cell proliferation.
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PMID:Peroxisome proliferators induce apoptosis in hepatoma cells. 967 79

Multidrug resistance (MDR) to anti-cancer agents is frequently associated with overexpression of the drug efflux transporter P-glycoprotein (Pgp) in cancer cells, ensuing drug expulsion and maintenance of tolerable intracellular levels of certain cytotoxic drugs. Pgp may also be present in normal tissue, providing protection against toxic substances, but the physiological role of Pgp is not fully understood. Recently, it was shown that Pgp also takes part in the transport of certain growth-regulating cytokines (Drach et al, 1996; Raghu et al, 1996). Therefore, we studied the effect of the highly potent Pgp inhibitor PSC 833 on proliferation of three pairs of MDR and parental human cell lines (HB8065 hepatoma cells, KG1a and K562 leukaemia cells). The MDR phenotypes were characterized by Pgp overexpression, which was demonstrated by flow cytometry using the anti-Pgp antibody MRK16. Electronic cell counting of 72-96 h cultures revealed a dose-dependent antiproliferative effect of PSC 833 in the resistant KG1a/200 and K562/150 cells. The half-maximal growth inhibitory concentrations (GI50) were 0.2 microM and 0.7 microM respectively. Exposure to PSC 833 induced cell death by apoptosis in both cell types, as revealed by flow cytometry and detection of 3'-hydroxy ends of DNA (the result of DNA fragmentation associated with apoptosis), by terminal transferase-mediated dUTP-biotin nick end-labelling (TUNEL). Similar effects were not found in the hepatoma cell lines or the parental leukaemia lines. These results demonstrated a discriminating cytotoxicity of PSC 833 in two human leukaemia MDR variants, representing a possible therapeutic indication which warrants consideration during the ongoing clinical evaluation of this drug.
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PMID:Cytotoxic effect of the cyclosporin PSC 833 in multidrug-resistant leukaemia cells with increased expression of P-glycoprotein. 974 97

The human hepatoma HepG2 cell line was chosen as a representative of solid tissue-derived cell systems in which folate metabolism and apoptosis induction have not been thoroughly investigated. HepG2 cells were cultivated in the control or folate-deficient media (control media lacking of folate, glycine, thymidine and hypoxanthine) for 4 wk. This resulted in a decrease in intracellular folate levels to 32% of the control within 1 wk, which was followed by growth arrest and greater cell death rates. These disturbances of folate deficiency coincided with apoptotic induction, as characteristically shown by nucleosomal DNA fragmentation of 180-200 base pair multimers, nuclear chromatin condensation and positive terminal transferase-mediated dUTP nick end labeling assay. Apoptosis coincided with an accumulation of cells in S-phase, a subsequent G2/M phase block and a significant increase in mean protein content as evaluated by flow cytometric analyses employing a double-staining method. The growth and cell cycle arrest under folate-deficient conditions was independent of a change of p53 expression as measured by an enzyme-linked immunosorbent assay. Supplementation of 2 micromol/L folate normalized cell cycles and diminished DNA fragmentation. Taken together, these data indicate that HepG2 cells cultivated in folate-deficient medium have a low folate concentration, decreased growth and viability, and increased apoptotic propensity. This occurrence of apoptosis was associated with a cell cycle-specific mechanism and independent of p53-mediated pathway.
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PMID:Folate deficiency induces a cell cycle-specific apoptosis in HepG2 cells. 991 71

The mechanisms involved in the anti-carcinogenic activity of selenium remain to be elucidated. In the present study, we examined sodium selenite-induced oxidative stress and apoptosis in a human hepatoma cell line (HepG2). Sodium selenite (10 microM) exerted clear cytotoxic effect, as shown by the significant increase of lactate dehydrogenase leakage. Selenite-induced DNA alterations in apoptosis were studied by: 1. comet assay; 2. TdT-mediated dUTP nick end-labeling assay. In addition, characteristic apoptotic morphological alterations were also observed in selenite-treated cells. Our results clearly show that Se-induced cell death occurs predominantly in the form of apoptosis. Selenite-induced oxidative stress was evaluated by the measurement of reactive oxygen species production using lucigenin-dependent chemiluminescence. The involvement of glutathione in selenite-induced oxidative stress was further demonstrated by the concurrent decline of intracellular reduced glutathione and increase of oxidized glutathione contents in Se-treated cells. Moreover, the finding that selenite-induced oxidative stress and apoptosis was significantly attenuated by superoxide dismutase, catalase and deferoxamine provides additional evidence to suggest that Se-induced oxidative stress mediates the induction of apoptosis, a mechanism related to the anti-carcinogenic and chemopreventive effect of Se.
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PMID:Sodium selenite-induced oxidative stress and apoptosis in human hepatoma HepG2 cells. 1032 39

The use of digoxigenin-labelled probes was studied for quantitation of HBV-DNA during antiviral drug evaluation. Digoxigenin (dig)-labelled probes were generated either via incorporation of dig-dUTP in a polymerase chain reaction (PCR) or a random priming reaction. Using the PCR-labelled probe (delineating a 523 bp fragment in the core gene of the HBV) as little as 1 pg of immobilized HBV-DNA could be detected following an 8 h exposure of the hybridized membrane. A close correlation (r = 0.95) was found between the amount of HBV-DNA (range 2.5-200 pg) and the signal generated by the probe hybridized to its target DNA. By using a probe that was labelled with digoxigenin via random priming, the minimal quantity of immobilized HBV plasmid DNA that could be detected following an 8 h exposure was 4 pg, whereas a 32P-labelled probe, generated in parallel by random priming, allowed the detection of 16 pg of HBV plasmid DNA following a 4-day exposure. The PCR-generated digoxigenin-labelled probe proved to be useful for antiviral drug evaluation, i.e. to detect HBV-DNA in total cellular DNA from HBV-positive hepatoma cells (HepG2.2.15) that had either been treated with reference antiviral agents or left untreated. The 50% effective concentrations (EC50) that were calculated for inhibition of HBV-DNA production by lamivudine (3TC), penciclovir (PCV), lobucavir (LBV), adefovir (PMEA) and tenofovir (PMPA) were comparable to those reported in the literature. The use of digoxigenin-labelled probes thus appears to be a simple, convenient, rapid, reliable and non-radioactive method for use for anti-HBV screening. In addition, and in contrast to 32P-labelled probes, digoxigenin-labelled probes can be stored for >1 year without loss of specific activity, which makes these probes particularly attractive for large-scale antiviral drug evaluation purposes.
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PMID:Use of digoxigenin-labelled probes for the quantitation of HBV-DNA in antiviral drug evaluation. 1048 73


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