Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: UMLS:C0019204 (hepatocellular carcinoma)
 71,386 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

An FMN-dependent NADH-quinone reductase is induced in Escherichia coli by growing the cells in the presence of menadione (2-methyl-1,4-naphthoquinone). Since the properties of induced enzyme are very similar to those of NAD(P)H: (quinone-acceptor) oxidoreductase (EC 1.6.99.2), known as DT-diaphorase, from animal cells, structural requirements of quinone derivatives as an inducer of NADH-quinone reductase in E. coli were examined. Among quinone derivatives examined, it was found that 2-alkyl-1,4-quinone structure with C-3 unsubstituted or substituted with Br is critical as a common inductive signal. Michael reaction acceptors which have been reported to be strong inducers of DT-diaphorase in mouse hepatoma cells were not always effective inducers in E. coli. However, several compounds, such as 2-methylene-4-butyrolactone, methylacrylate and methyl vinyl ketone, showed a slight inductive activity. The efficient inducers of NADH-quinone reductase in E. coli contain 1,4-quinone structure as a part of the inductive signal. These compounds belong to Michael acceptors and are likely to conjugate with thiol compounds such as glutathione.
 ...
PMID:Chemical structures critical for the induction of FMN-dependent NADH-quinone reductase in Escherichia coli. 154 1

Menadione (vitamin K3, 2-methyl-1,4-naphthoquinone) is a synthetic derivative of napthoquinone. Its ability to inhibit cell growth in a wide variety of and human tumor cell types, and in rat hepatocytes has been recognized. Using a rat transplantable hepatoma model, we have evaluated the cytotoxic activity of menadione in hepatoma cells. Tumor cells in culture were sensitive to menadione treatment. The ID50 of drug is 3.4 microM as shown by a colorimetric MTT (3-(4,5-dimethythiazol-2-yl)-2,5-diphenyltetrazolium bromide) assay. Tumor-bearing rats were randomized into the treatment (n = 16) and control (n = 15) groups. Rats in the treatment group received intraperitoneal injection of menadione (10 mg/2 ml) once a week for four times; the control group received 2 ml water instead. None of the control rats survived after the 17th day following the start of treatment, while 5 out of the 16 treated rats responded well and survived long-term (greater than 60 days). Medadione was shown to inhibit actively the growth of hepatoma cells in vitro as well as in vivo.
 ...
PMID:The in vitro and in vivo cytotoxicity of menadione (vitamin K3) against rat transplantable hepatoma induced by 3'-methyl-4-dimethyl-aminoazobenzene. 177 38

Exposure of hepatoma 1c1c7 cells to 2,3-dimethoxy-1,4-naphthoquinone (DMNQ) resulted in a sustained elevation of cytosolic Ca2+, DNA single strand breaks and cell killing. DNA single strand break formation was prevented when cells were preloaded with either of the intracellular Ca2+ chelators, Quin 2 or BAPTA, to buffer the increase in cytosolic Ca2+ concentration induced by the quinone. DMNQ caused marked NAD+ depletion which was prevented when cells were preincubated with 3-aminobenzamide, an inhibitor of nuclear poly-(ADP-ribose)-synthetase activity, or with either of the two Ca2+ chelators. However, 3-aminobenzamide did not protect the hepatoma cells from loss of viability. Our results indicate that quinone-induced DNA damage, NAD+ depletion and cell killing are mediated by a sustained elevation of cytosolic Ca2+.
 ...
PMID:Intracellular Ca2+ chelators prevent DNA damage and protect hepatoma 1C1C7 cells from quinone-induced cell killing. 235 10

We describe a rapid and direct assay of NAD(P)H:(quinone-acceptor) oxidoreductase (EC 1.6.99.2) activity in cultured cells suitable for identifying and purifying inducers of this detoxication enzyme. Hepa 1c1c7 murine hepatoma cells are plated in 96-well microtiter plates, grown for 24 h, and exposed to inducing agents for another 24 h. The cells are then lysed and quinone reductase activity is assayed by the addition of a reaction mixture containing an NADPH-generating system, menadione (2-methyl-1,4-naphthoquinone), and MTT [3-(4,-5-dimethylthiazo-2-yl)-2,5-diphenyltetrazolium bromide]. Quinone reductase catalyzes the reduction of menadione to menadiol by NADPH, and MTT is reduced nonenzymatically by menadiol resulting in the formation of a blue color which can be quantitated on a microtiter plate absorbance reader. The reaction is more than 90% dicoumarol inhibitable and menadione dependent. The results are comparable to those obtained by harvesting cells from larger plates, preparing cytosols, and carrying out spectrophotometric measurements.
 ...
PMID:Direct measurement of NAD(P)H:quinone reductase from cells cultured in microtiter wells: a screening assay for anticarcinogenic enzyme inducers. 338 6

Congeners of vitamin K are known to inhibit cell growth, although the precise mechanisms of growth inhibition are not well understood. To investigate the mechanisms involved, we synthesized several vitamin K analogs and examined their growth inhibitory activities for a human hepatoma cell line (Hep3B). The analogs included 2-methyl-1,4-naphthoquinone and trimethyl-benzoquinone, with and without aliphatic side chains at position 3. The side chains were all-carbon, thioethers, or O-ethers. Growth inhibition was potent in the compounds with short chains. The presence of a sulfur (thioether) or oxygen atom (O-ether) at the site of attachment of the side chain to the ring potentiated the activity. Apoptotic cell death was induced by the potent growth inhibitory compounds at low concentrations (20-60 microM), whereas necrotic cell death followed treatment with the same compounds at high concentrations. Expression of c-myc, which is thought to be associated with apoptosis, was increased by most of the compounds tested. Both reduced glutathione and cysteine almost completely abrogated the growth inhibitory effects of the thioether analogs as well as of vitamin K3. The effect of glutathione was less prominent for the all-carbon and O-ether analogs, and cysteine had no effect on these analogs. Catalase and deferoxamine mesylate had no significant effect on the thioether analogs, although they showed partial antagonistic effects on the growth inhibition of vitamin K3 and the all-carbon and O-ether analogs. Other non-thiol antioxidants tested had no effect on any of the analogs. Our results indicated that vitamin K-related quinoid compounds cause growth inhibition and both apoptotic and necrotic cell death and that the effects may be mediated by interaction at position 3 of their quinoid nuclei with cellular thiols.
 ...
PMID:Growth inhibition of hepatoma cells induced by vitamin K and its analogs. 749 29

Using the human hepatoma cell line, HepG2, and the BALB/c mouse fibroblast cell line, 3T3, as the bioindicators in the neutral red cytotoxicity assay, the effect of hydroxyl substitution on the toxicity of 1,4-naphthoquinone was studied. The sequence of potency for the quinones was 5,8-dihydroxy-1,4-naphthoquinone > 5-hydroxy-1,4-naphthoquinone > 1,4-naphthoquinone >> 2-hydroxyl-1,4- naphthoquinone. Pretreatment of the cells with dicoumarol, an inhibitor of DT-diaphorase, enhanced the cytotoxicity of 1,4-naphthoquinone but not of the hydroxylated naphthoquinones. Pretreatment of the BALB/c cells with buthionine sulfoximine, an inhibitor of glutathione synthesis, enhanced the sensitivity of the cells to all the hydroxylated naphthoquinones but not to 1,4-naphthoquinone. A similar pretreatment of the HepG2 cells with buthionine sulfoximine enhanced the toxicity of the 2-hydroxy- and 5,8-dihydroxy-1,4-naphthoquinones but not of 5-hydroxy-1,4-naphthoquinone or of 1,4-naphthoquinone. Some differences were noted in the responses to the hydroxylated 1,4-naphthoquinones between buthionine sulfoximine-treated replicating cells and buthionine sulfoximine-treated isolated rat hepatocytes, a nonreplicating cell in culture. The use of a replicating cell system in studying the mechanisms of the cytotoxicity of quinones may be an important adjunct to studies using the isolated rat hepatocytes, which is the standard model system.
 ...
PMID:In vitro cytotoxicities of 1,4-naphthoquinone and hydroxylated 1,4-naphthoquinones to replicating cells. 750 9

Bluegill sunfish BF-2 fibroblasts were used to evaluate the in vitro cytotoxicities of 1,4-naphthoquinone (NQ), 5,8-dihydroxy-1,4-NQ, and 2,3-dichloro-1, 4-NQ (dichlone); comparisons were made with previously obtained data on the response of human hepatoma HepG2 cells. For both cell types, the sequence of potency was 5,8-dihydroxy-1,4-NQ > 1,4-NQ > dichlone. Dichlone, and, although to a lesser extent, 1,4-NQ and 5,8-dihydroxy-1-4-NQ, induced endoreduplication in the BF-2 cells; for the HepG2 cells, endoreduplication was induced only with dichlone. Exposures to the three NQs reduced intracellular glutathione levels in both cell types. For the BF-2 and HepG2 cells, pretreatments with buthionine sulfoximine (BSO), a glutathione-depleting agent, potentiated the cytotoxicity of 5,8-hydroxy-1,4-NQ and dichlone; pretreatment with dicoumarol, an inhibitor of DT-diaphorase, had no effect on toxicity of these two NQs. Apparently, for these two quinones the predominant metabolic pathway in both the BF-2 and HepG2 cells involved redox cycling via a one-electron reduction reaction, generating reactive oxygen intermediates that consumed intracellular glutathione. Pretreatment of the BF-2 cells with BSO, but not with dicoumarol, potentiated the toxicity of 1,4-NQ, again indicating that metabolism occurred via one electron reduction. However, for the HepG2 cells, pretreatment with dicoumarol, but not with BSO, potentiated the cytotoxicity of 1,4-NQ. Apparently, in the HepG2, as compared to the BF-2, cells, 1,4-NQ was metabolized by DT-diaphorase in a reaction involving a two electron reduction.
 ...
PMID:Naphthoquinone cytotoxicity to bluegill sunfish BF-2 cells. 802 24

Plumbagin (5-hydroxy-2-methyl-1,4-naphthoquinone) isolated from Plumbago zeylanica Linn, when administered orally, at a dosage of 4 mg/kg body weight induces tumour regression in 3-methyl-4-dimethyl aminoazobenzene (3MeDAB) induced hepatoma in Wistar male rats. The purpose of this investigation was to identify the changes in the rate of glycolysis and gluconeogenesis in tumour-bearing rats and the effects of treatment with Plumbagin. The levels of certain glycolytic enzymes, namely, hexokinase; phosphoglucoisomerase; and aldolase levels increased (p < 0.001) in hepatoma bearing rats, whereas they decreased in Plumbagin administered rats to near normal levels. Certain gluconeogenic enzymes, namely, glucose-6-phosphatase and fructose-1,6-diphosphatase decreased (p < 0.001) in tumour hosts, whereas Plumbagin administration increased the gluconeogenic enzyme levels in the treated animals. These investigations indicate the molecular basis of the different biological behaviour of 3MeDAB induced hepatoma and the anticarcinogenic property of Plumbagin against hepatoma studied in rats.
 ...
PMID:Effect of Plumbagin on some glucose metabolising enzymes studied in rats in experimental hepatoma. 826 73

We have shown that a synthetic vitamin K analog, 2-(2-mercaptoethanol)-3-methyl-1,4-naphthoquinone or compound 5 (Cpd 5), potently inhibits cell growth and suggested that the analog exerts its effects mainly via sulfhydryl arylation rather than redox cycling. Since protein-tyrosine phosphatases (PTPases), which have pivotal roles in many cellular functions, have a critical cysteine in their active site, we have proposed PTPases as likely targets for Cpd 5. To test this hypothesis, we examined the effects of Cpd 5 on protein tyrosine phosphorylation of cellular proteins and on the activity of PTPases. We found that Cpd 5 rapidly induced protein tyrosine phosphorylation in a human hepatocellular carcinoma cell line (Hep3B) at growth inhibitory doses, and the effect was blocked by thiols but not by non-thiol antioxidants or tyrosine kinase inhibitors. Cpd 5 inhibited PTPase activity, which was also significantly antagonized by reduced glutathione. Furthermore, the well studied PTPase inhibitor orthovanadate also induced protein tyrosine phosphorylation and growth inhibition in Hep3B cells. These results suggest that inhibition of cellular PTPases by sulfhydryl arylation and subsequent perturbation of protein tyrosine phosphorylation may be involved in the mechanisms of Cpd 5-induced cell growth inhibition.
 ...
PMID:Cell growth inhibition by a novel vitamin K is associated with induction of protein tyrosine phosphorylation. 954 33

Expression of the MRP1 gene encoding the GS-X pump and of the gamma-GCSh gene encoding the heavy (catalytic) subunit of the gamma-glutamylcysteine synthetase is frequently elevated in many drug-resistant cell lines and can be co-induced by many cytotoxic agents. However, mechanisms that regulate the expression of these genes remain to be elucidated. We report here that like gamma-GCSh, the expression of MRP1 can be induced in cultured cells treated with pro-oxidants such as tert-butylhydroquinone, 2,3-dimethoxy-1, 4-naphthoquinone, and menadione. Intracellular reactive oxygen intermediate (ROI) levels were increased in hepatoma cells treated with tert-butylhydroquinone for 2 h as measured by flow cytometry using an ROI-specific probe, dihydrorhodamine 123. Elevated GSH levels in stably gamma-GCSh-transfected cell lines down-regulated endogenous MRP1 and gamma-GCSh expression. ROI levels in these transfected cells were lower than those in the untransfected control. In the cell lines in which depleting cellular GSH pools did not affect the expression of the MRP1 and gamma-GCSh genes, only minor increased intracellular levels of ROIs were observed. These results suggest that intracellular ROI levels play an important role in the regulation of MRP1 and gamma-GCSh expression. Our data also suggest that elevated intracellular GSH levels not only facilitate substrate transport by the MRP1/GS-X pump as previously demonstrated, but also suppress MRP1 and gamma-GCSh expression.
 ...
PMID:Expression of multidrug resistance protein/GS-X pump and gamma-glutamylcysteine synthetase genes is regulated by oxidative stress. 981 7


1 2 3 4 5 Next >>