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)

The cytochrome P450 1B1 gene (CYP1B1) is expressed constitutively and is inducible by 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) in the human breast adenocarcinoma cell line MCF-7 but not in the human hepatoma cell line HepG2. Genomic DNA isolated from both cell lines was digested with the methylation-sensitive restriction enzyme isoschizomers MspI and HpaII, and subjected to Southern analysis with a probe for the CYP1B1 promoter/enhancer region. Although differences were observed in methylation patterns for the CYP1B1 gene from MCF-7 and HepG2 cells, treatment with the demethylating agent 5-azacytidine (10 microM for 6 days) did not activate CYP1B1 mRNA expression in HepG2 cells. Furthermore, treatment with the histone deacetylase inhibitor trichostatin A (100 nM for 24 h) did not activate CYP1B1 mRNA expression in HepG2 cells. Comparative analysis of the constitutive expression of luciferase/1B1 reporter constructs containing a series of deletions in the 5' enhancer region indicated that in MCF-7 cells the region from -987 to -732 (relative to the transcription start site) was necessary for maximal levels of activity. Mutation of the aryl hydrocarbon receptor response elements (dioxin response elements) in this region showed that the dioxin response elements located at -833 is essential for constitutive gene expression in MCF-7 cells. In HepG2 cells, reporter gene activity was at least equal or greater than the activity observed in MCF-7 cells, which is in marked contrast to the expression of the native CYP1B1 gene. Taken together these findings indicate that the observed cell-specific differences in CYP1B1 constitutive expression are not mediated by DNA promoter/enhancer methylation, but are likely due to either 1) inaccessibility of the 5'-enhancer region in HepG2 cells to transcriptional activators due to a higher order chromatin structure that does not involve histone acetylation, or 2) the action of a repressor protein at cis-elements located outside of the -2296 to +25 region examined with the CYP1B1 reporter constructs. Furthermore, at least one of the dioxin response elements in the enhancer region is required for constitutive expression of CYP1B1.
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PMID:Transcriptional regulation of the human CYP1B1 gene. Evidence for involvement of an aryl hydrocarbon receptor response element in constitutive expression. 1070 33

Impaired function of apoptosis-related genes is deeply involved in oncogenesis and the progression of cancers, and caspase-3 plays a critical role as an executioner of apoptosis. We introduced the caspase-3 gene via an adenovirus (Adv) vector into Alexander hepatoma cells, MCF-7 breast cancer cells, and U251 and U-373MG glioma cells which have different endogenous levels of caspase-3 expression. None of the cell lines underwent apoptosis by overexpression of caspase-3, indicating that induction of caspase-3 alone is not applicable for cancer gene therapy. Next, we investigated whether overexpression of caspase-3 could enhance Fas ligand-mediated apoptosis in these four cell lines. In U-373MG cells, which showed the highest level of expression of surface Fas among the four cell lines, coinfection of the Adv for caspase-3 (Adv-caspase-3) and the Adv for Fas ligand (Adv-FL) induced a remarkably increased degree of apoptosis compared with that induced by the single infection of either Adv-caspase-3 or Adv-FL. Similar results were obtained by cotreatment with anti-Fas antibody in U-373MG cells. These data suggest that when strong proapoptotic upstream stimuli are induced, the level of caspase-3 expression determines the degree of apoptosis in cancer cell lines. In conclusion, overexpression of caspase-3 alone did not induce apoptosis in cancer cells. Both a strong proapoptotic signal and a high expression of caspase-3 were required to induce drastic apoptosis in cancers. This strategy would be highly beneficial for selected cancer patients.
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PMID:Adenovirus-mediated transfer of caspase-3 with Fas ligand induces drastic apoptosis in U-373MG glioma cells. 1077 15

Total RNA and poly(A)+ RNA were isolated from tissues and cultured cells of various mammalian species (bovine muzzle epidermis and bladder urothelium; rat hepatoma cells; human cell lines HeLa, MCF-7 and A-431) and examined by translation in vitro using the reticulocyte lysate system. Polypeptides were separated and identified by two-dimensional electrophoresis and cytokeratins were selectively enriched from the translation assays by co-polymerization with added heterologous cytokeratins. In all three species, non-epidermal cytokeratins A, D and mol. wt. 40,000 (corresponding to numbers 8, 18 and 19 of the human cytokeratin catalog of Moll et al., 1982) were identified as translation products capable of co-polymerization with epidermal keratins. Several other basic and other acidic cytokeratins were also identified as translational products. In addition, two unidentified polypeptides (mol. wt. 52,000 and 43,000) which were minor polypeptides in cytoskeletons and translation assays were found to be specifically enriched in co-polymers with bovine epidermal keratins. The results indicate that many, perhaps all, non-epidermal cytokeratins characteristic of simple epithelia are genuine products of translation and that their diversity is not due to post-translational modification or processing. These findings, taken together with observations of in vitro translation of epidermal mRNAs, suggest that the diversity of cell type-specific expression of the different members of the cytokeratin polypeptide family is largely due to the cell type-specific synthesis of diverse mRNAs.
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PMID:Translational products of mRNAs coding for non-epidermal cytokeratins. 1087 35

A full-length, PRL-inducible complementary DNA (cDNA) encoding a novel, nuclear-targeted carboxypeptidase D isoform (designated CPD-N) was identified in the rat PRL-dependent Nb2-11C and PRL-independent Nb2-Sp lymphoma cell lines by differential display. The CPD-N cDNA (3751 bp) has 99% (3582/3583) homology with rat carboxypeptidase D (CPD; 4377 bp). In comparison to the rat CPD cDNA (ORF of 4134 bp; 180-kDa protein), CPD-N was shorter by approximately 600 bases but contained 148 unique bases at the 5'-end to give an ORF of 3399 bp. RT-PCR with primers specific to the 5'-end of CPD-N or to CPD showed that the CPD-N transcript was expressed in the Nb2-11C and Nb2-Sp cells but was not detected in rat brain or lung. Conversely, the CPD transcript was expressed in rat brain but was not detected in the two Nb2 cell lines. CPD-N expression (7.5-kb messenger RNA) was stimulated by PRL (10 ng/ml) and/or by interleukin-2 (24 U/ml) in Nb2-11C and Nb2-Sp cells. Most rat tissues expressed multiple CPD transcripts (7.5, 4.1, and 2 kb). Curiously, CPD transcripts were low or undetectable in male rat liver but readily detected in female liver, suggesting that sex-specific hormone levels may regulate its expression. Indeed, CPD expression in the PRL-responsive HepG2 hepatoma and MCF-7 breast cancer cell lines was low in control cells but was markedly stimulated by PRL after 3 h. Consistent with the shorter ORF of CPD-N, Western analysis detected proteins of smaller molecular sizes of 160 kDa (abundant) and 117 kDa (weak) in the Nb2-11C cells. The Nb2-Sp cells expressed a single and abundant 117-kDa protein, implicating differential protein processing in the two cell lines. Rat CPD has been reported to colocalize with the trans-Golgi network marker TGN38. Subcellular fractionation showed predominant nuclear localization of CPD-N and trace amounts were detected in the 100,000 x g microsomal fraction after PRL treatment (4 h); in contrast, TGN38 was found only in the microsomal fraction at this time. In cells treated with PRL for 24 h, immunofluorescent confocal microscopy showed nuclear and cytoplasmic distribution of CPD-N. Cytoplasmic CPD-N colocalized with TGN-38 whereas nuclear CPD-N had a mesh-like distribution and colocalized with nuclear lamin B.
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PMID:Identification and nuclear localization of a novel prolactin and cytokine-responsive carboxypeptidase D. 1118 55

Nrf2 regulates expression of genes encoding enzymes with antioxidant (e.g. heme oxygenase-1 (HO-1)) or xenobiotic detoxification (e.g. NAD(P)H:quinone oxidoreductase, glutathione S-transferase) functions via the stress- or antioxidant-response elements (StRE/ARE). Nrf2 heterodimerizes with small Maf proteins, but the role of such dimers in gene induction is controversial, and other partners may exist. By using the yeast two-hybrid assay, we identified activating transcription factor (ATF) 4 as a potential Nrf2-interacting protein. Association between Nrf2 and ATF4 in mammalian cells was confirmed by co-immunoprecipitation and mammalian two-hybrid assays. Furthermore, Nrf2.ATF4 dimers bound to an StRE sequence from the ho-1 gene. CdCl(2), a potent inducer of HO-1, increased expression of ATF4 in mouse hepatoma cells, and detectable induction of ATF4 protein preceded that of HO-1 (30 min versus 2 h). A dominant-negative mutant of ATF4 inhibited basal and CdCl(2)-stimulated expression of a StRE-dependent/luciferase fusion construct (pE1-luc) in hepatoma cells but only basal expression in mammary epithelial MCF-7 cells. A dominant mutant of Nrf2 was equally inhibitory in both cell types in the presence or absence of CdCl(2). These results indicate that ATF4 regulates basal and CdCl(2)-induced expression of the ho-1 gene in a cell-specific manner and possibly in a complex with Nrf2.
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PMID:Identification of activating transcription factor 4 (ATF4) as an Nrf2-interacting protein. Implication for heme oxygenase-1 gene regulation. 1127 84

Dioxin and pesticides with xenoestrogenic activity are environmental contaminants that are suspected of promoting human diseases such as cancers. However, few studies have addressed the molecular consequences of a combination of these contaminants, a situation that is likely to occur in the environment. We investigated the effects of natural and xenoestrogens on basal and 2,3,7,8-tetrachlorodibenzo-p-dioxin-induced cytochrome P450 (CYP) 1A1 and 1B1. The CYP1B1/1A1 ratio is a critical determinant of the metabolism and toxicity of estradiol in mammary cells. Here we show that in MCF-7 cells, 17beta-estradiol and alpha-endosulfan can repress whole cell ethoxyresorufin-O-deethylase activity, lowering CYP1A1 mRNA levels as well as promoter activity as assessed by transient transfection assays. These negative effects are observed at both the basal and tetrachlorodibenzo-p-dioxin-induced levels. Under the same conditions, CYP1B1 mRNA levels and promoter activity are not affected. The effects on mRNA-induced levels are also observed in another mammary cell line, T47D, but not in mammary cell lines that do not express aryl hydrocarbon receptor and estrogen receptor (ER). Moreover, the use of ER antagonists shows that these effects are ER dependent in MCF-7 cells. In human hepatoma HepG2 cells, which lack functional ER, alpha-endosulfan, but not 17beta-estradiol, displays a repressive effect on CYP1A1 through a different mechanism. These results show that xenoestrogens, by altering the ratio of CYP1B1/CYP1A1, could redirect estradiol metabolism in a more toxic pathway in the breast cell line MCF-7.
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PMID:Differential regulation of cytochrome P450 1A1 and 1B1 by a combination of dioxin and pesticides in the breast tumor cell line MCF-7. 1135 10

Intracellular metabolism of methotrexate (MTX) to MTX-polyglutamates (MTXPG) is one determinant of cytotoxicity. Steady-state accumulation of MTXPG seems to depend on the activity of two enzymes: folylpolyglutamate synthetase (FPGS), which adds glutamate residues, and gamma-glutamyl hydrolase (GGH), which removes them. Overexpression of GGH would be expected to decrease intracellular MTXPG, thereby increasing efflux of MTX and decreasing cytotoxicity. Increased expression of GGH has been shown to be associated with resistance to MTX in human sarcoma cell lines and a rat hepatoma cell line. To clarify the specific role of GGH in determining MTX sensitivity, we investigated the phenotype produced by forced GGH overexpression in two cell types. Furthermore, because MTX and folic acid share metabolic pathways, we measured the effects of GGH overexpression on folic acid metabolism. The full-length cDNA for GGH, subcloned into a constitutive expression vector, was transfected into a human fibrosarcoma (HT-1080) and a human breast carcinoma (MCF-7) cell line. Compared with the clones containing an empty vector, the GGH-overexpressing cells express 15- to 30-fold more GGH mRNA, more GGH protein, and 15- to 90-fold more GGH enzyme activity. GGH overexpression altered MTX accumulation and metabolism to long-chain polyglutamates. In contrast to expectations, however, GGH overexpression did not confer resistance to short MTX exposures in either cell line. Changes in MTX metabolism were found to be balanced by alterations in accumulation and metabolism of folic acid. The ratio of MTX:folate accumulation may be a better predictor of MTX cytotoxicity than the accumulation of either alone. We conclude that, at least for these two cell lines, GGH overexpression alone is insufficient to produce clinical resistance to MTX.
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PMID:Effects of overexpression of gamma-Glutamyl hydrolase on methotrexate metabolism and resistance. 1138 96

A coumestan derivative, psoralidin (1) was found to be a cytotoxic principle of the seeds of Psoralea corylifolia L. (Leguminosae) with the IC50 values of 0.3 and 0.4 microg/ml against the HT-29 (colon) and MCF-7 (breast) human cancer cell lines, respectively. A coumarin, angelicin (2) was also isolated as a marginally cytotoxic agent along with an inactive compound, psoralen (3) from the plant. The isolates 1-3 were not active against the A541 (lung) and HepG2 (liver hepatoma) cancer cell lines.
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PMID:Cytotoxic constituents of Psoralea corylifolia. 1144 79

Emodin (3-methyl-1,6,8-trihydroxyanthraquinone) is an active compound of many laxative herbal drugs. The present study aimed to determine the effects of emodin on cytochrome P450 (P450)-dependent monooxygenases of human lung adenocarcinoma CL5 cells. Treatment of CL5 cells with 100 microM emodin for 24 h induced benzo[a]pyrene hydroxylation, 7-ethoxyresorufin O-deethylation, and 7-ethoxycoumarin O-deethylation activities of S9 fractions. Immunoblot analysis of CL5 S9 proteins revealed that emodin induced proteins immunorelated to P450s 1A1 and 1B1. Northern blot analysis of total cellular RNA showed that emodin induced P450s 1A1 and 1B1 mRNA levels in CL5 cells. These inductive effects on P450 monooxygenase activity, protein, and mRNA were concentration- and time-dependent. Addition of emodin to CL5 cell microM S9 inhibited its 7-ethoxycoumarin O-deethylation activity. Treatment of CL5 cells with 10 microM 3-methylcholanthrene for 24 h induced monooxygenase activity and P450s 1A1 and 1B1 proteins and mRNA levels. Treatment of the lung cells with 100 microM emodin or purpurin (1,2,4-trihydroxyanthraquinone) for 24 h produced greater induction of P450s 1A1 and 1B1 mRNA than did anthraflavic acid (2,6-dihydroxyanthraquinone) or anthraquinone. The emodin treatment induced P450s 1A1 and 1B1 mRNA in human lung carcinoma NCI-H322 and breast cancer MCF-7 cells. Emodin induced P450 1A1, but not 1B1, mRNA in human hepatoma HepG2 cells. The present study demonstrates that emodin is an inducer of P450s 1A1 and 1B1 protein and mRNA in human lung adenocarcinoma CL5 cells. Modulation of P450 by emodin may be an important factor affecting metabolism and toxicity of the hydroxyanthraquinone in humans.
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PMID:Induction of cytochromes P450 1A1 and 1B1 by emodin in human lung adenocarcinoma cell line CL5. 1150 33

Antibiotic G0069A, produced by a Streptomyces strain isolated from a soil sample collected in Yunnan Province, China, has been verified as a clavam peptide. Determined by MTT assay, G0069A showed highly potent cytotoxicity to cancer cells with multidrug resistance. The IC50 values of G0069A to KB and KB/VCR cells were 0.60 and 0.46 mumol.L-1, and to MCF-7 and MCF-7/ADM cells were 1.4 and 1.2 mumol.L-1, respectively. G0069A displayed equally potent cytotoxicity to the parent cell lines and their resistant sublines. When administered by i.v. or i.p. route at tolerable doses, G0069A exhibited markedly inhibitory effect on the growth of sarcoma 180 and hepatoma 22 in mice. At dose level of 3 mg.kg-1, i.v., x3, sarcoma 180 and hepatoma 22 were suppressed by 87%(P < 0.01) and 72%(P < 0.01), respectively. The results indicate that G0069A is a beta-lactam antibiotic showing antitumor activity.
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PMID:[Antitumor activity of the clavam peptide antibiotic G0069A]. 1159 87


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