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)

Hydroxycamptothecin (HCPT), isolated from Camptotheca acuminata, is a powerful antitumor alkaloid. Previous studies indicated that the molecular target of this agent was DNA topoisomerase I. The present results demonstrated that in vitro treatment of murine ascites hepatoma cells with HCPT resulted in a marked reduction in DNA syntheses and the inhibition of phosphorylation in histone was in a time-dependent manner. Gel electrophoresis found that HCPT had a selectively inhibitory effect on the phosphorylation of histone H1 and H3, but less effect on the other kinds of histones. In vivo, HCPT also exhibited a suppressive effect on histone H1 and H3 phosphorylation. These data suggested that HCPT-induced cell killing may be, at least in part, associated with the suppression of histone H1 and H3 phosphorylation.
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PMID:Inhibition of phosphorylation of histone H1 and H3 induced by 10-hydroxycamptothecin, DNA topoisomerase I inhibitor, in murine ascites hepatoma cells. 801 56

The conformational peculiarities of DNA and histones of chromatins of different origin have been studied using circular dichroism (CD). The chromatins were isolated from pigeon brain, rat thymus and liver, ascitic hepatoma 22A, C3HA mouse liver, pigeon erythrocytes and sea urchin sperm. The functional peculiarities of the chromatins were found to correlate with their compactness and the nucleosomal DNA repeat length. Analysis of chromatin CD spectra made it possible to define the degree of DNA compactness in oligonucleosomes and the secondary structure of their linker histones of the H1 family. It was found that in low ionic strength solutions the structures of chromatosomes are formed in erythrocyte and thymus chromatins, but not in sea urchin sperm chromatin. The size of the compact part of the DNA in the nucleosomes of transcriptionally active chromatins of brain and ascitic hepatoma 22A are less than the length of the DNA of the core particles under identical conditions. The secondary structure of the H1 histone from sea urchin sperm chromatin, unlike other linker histones of the H1 family, contains an additional alpha-helical segment in the C-terminal part. Analysis of structural changes of the both chromatin components during condensation of their oligonucleosomal chains with an increase in the ionic strength has been carried out.
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PMID:[Features of structural organization of chromatin from various sources]. 826 3

Since protein binding to the 3' end of mRNA is believed to be involved in the control of mRNA stability, the time course of alterations in glucagon-induced phosphoenolpyruvate-carboxykinase-mRNA (PCK) levels, in the absence and presence of insulin, was correlated with the time course of changes in the binding of cytosolic protein from 24-h cultured rat hepatocytes to the 3' end of PCK mRNA. PCK-mRNA levels were monitored by Northern blot analysis and protein binding was analyzed by an electrophoretic mobility-shift assay. In 24-h cultured rat hepatocytes, binding of cytosolic protein to the PCK-mRNA 3' end and PCK-mRNA levels were increased to a transient maximum at 2 h and 2-4 h, respectively, by a 1-nM glucagon treatment, added with a change of medium. 100 nM insulin, added simultaneously with glucagon, reduced the glucagon-induced maximum of protein binding by 80% and the increase of PCK mRNA by about 30%. In controls without hormonal treatment protein binding at 1 h was also increased; this increase was prevented by insulin. 100 nM insulin, added 1 h after glucagon, reversed protein binding to the 3' end of PCK mRNA to nearly initial levels within 1 h and impaired the glucagon-induced increase in PCK-mRNA levels by 30%. The transcriptional inhibitor cordycepin, added 1 h after glucagon, did not prevent the further increase in glucagon-enhanced protein binding nor its reversal by insulin. It did, however, prevent a further significant increase in PCK mRNA. Hormonally regulated protein binding could be localized to the 256 distal bases of the PCK-mRNA 3' end. The proximal 466 bases of the PCK-mRNA 3' end as well as the 1050 bases of the histone-H1(0)-mRNA 3' end and the 1200 bases of the arylsulfatase-A-mRNA 3' end also bound cytosolic protein(s), but this protein binding was not altered by treatment with glucagon or insulin. The 3' end of PCK, arylsulfatase A and H1(0) mRNA exhibited strong binding of cytosolic protein(s) from diverse rat tissues such as heart, liver and lung as well as Fao rat hepatoma cells. Cytosolic protein(s) from spleen showed weak binding and proteins from HeLa and U937 tumor cells did not bind. Protein binding was most prominent with the 3' end of PCK mRNA and cytosolic extracts from liver.(ABSTRACT TRUNCATED AT 400 WORDS)
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PMID:The glucagon-insulin antagonism in the regulation of cytosolic protein binding to the 3' end of phosphoenolpyruvate carboxykinase mRNA in cultured rat hepatocytes. Possible involvement in the stabilization of the mRNA. 835 60

Hepatomas tend to have a decreased glucose-6-phosphatase activity. We have observed phenotypic stability for this change in Morris hepatomas transplanted in rats. To determine if this decrease is selective for translocase functions or the hydrolase activity associated with glucose-6-phosphatase, we have compared activities in liver and hepatomas with glucose-6-phosphate or mannose-6-phosphate as substrates and with intact or histone-disrupted microsomes. In five out of seven subcutaneously transplanted rat hepatoma lines, the microsomal mannose-6-phosphatase activity was lower than in preparations from liver of normal or tumor-bearing rats. With liver microsomes and with most hepatoma microsomes, preincubation with calf thymus histones caused a greater increase in mannose-6-phosphatase than in glucose-6-phosphatase activity. In studies with liver and hepatoma microsomes there were similar increases in mannose-6-phosphatase activity with total calf thymus histones and arginine-rich histones. A smaller increase was seen with lysine-rich histones. The effect of polylysine was similar to the action of lysine-rich histones. There was only a small effect with protamine at the same concentration (1 mg/ml). Rat liver or hepatoma H1 histones gave only about half the activation seen with core nucleosomal histones. Our data suggested that microsomes of rat hepatomas tend to have decreased translocase and hydrolase functions of glucose-6-phosphatase relative to activities in untransformed liver.
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PMID:Changes in the glucose-6-phosphatase complex in hepatomas. 839 4

The search for cancer specific nuclear proteins, stimulated by the supposition that transition from the normal to the neoplastic state resulting from disturbances in the control mechanisms of gene expression, indicated that non-histone protein of MW 48 kD is much more abundant in animal tumour cells than in normal liver (Krajewska et al., 1990). A non-histone component of MW 48 kD was assessed for changes during chemically induced carcinogenesis. Rats were treated with the hepatocarcinogen thioacetamide (TAA) and the expression of the polypeptide studied, in total nuclear protein and nonhistone protein fractions, was tested by Western blot technique in the presence of antibodies developed against a component of MW 48 kD from Kirkman-Robbins hepatoma. It was demonstrated that TAA-induced hepatocarcinogenesis was accompanied by the expression of non-histone protein of MW 48 kD at a significantly elevated level. A clear and distinct change in the expression of the component studied in the spleen of TAA-treated rats was also observed. These results support the suggestion that over-expression of non-histone protein of MW 48 kD could contribute to neoplastic transformation.
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PMID:Thioacetamide-stimulated expression of non-histone protein. 840 30

Butyramide and monobutyrin were chosen for study as neutral compounds that might exhibit some of the growth inhibitory and differentiating effects of butyrate. Inhibitory effects on DNA synthesis in hepatoma cells and on cellular proliferation in mouse erythroleukemia cells were observed. Induction of differentiation by butyramide and monobutyrin was seen in mouse erythroleukemia cells as monitored by increased synthesis of hemoglobin and H1 zero histone. Butyramide and monobutyrin were less effective inducers of hemoglobin synthesis than butyrate but their neutral character may offer an advantage in the induction of tumor cell differentiation.
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PMID:Butyramide and monobutyrin: growth inhibitory and differentiating agents. 847 5

Over 50% of the hepatocellular carcinomas (HCCs) arising in the livers of woodchucks with persistent woodchuck hepatitis virus (WHV) infection contain integrations of WHV DNA within, or immediately adjacent to, a unique and functional N-myc 2 retroposon [G. Fourel et al., Nature (Lond.), 347: 294-298, 1990; Y. Wei et al., J. Virol., 66: 5265-5276, 1992]. The integrations are believed to activate the expression of N-myc 2 by an enhancer insertion mechanism [Y. Wei et al., J. Virol., 66: 5265-5276, 1992]. Since the fetal growth factor insulin-like growth factor II (IGF-II) is also expressed in woodchuck HCCs [X. X. Fu et al., J. Virol., 62: 3422-3430, 1988; D. Yang and C. E. Rogler, Carcinogenesis (Lond.), 12: 1893-1901, 1991] we sought to determine the earliest stage in hepatocarcinogenesis at which overexpression of N-myc and IGF-II could be detected. The earliest precancerous lesions so far identified in woodchucks are altered hepatic foci (AHFs) [K. Abe et al., Jpn. J. Cancer Res., 79: 466-472, 1988; H. Popper et al., Hepatology (Baltimore), 1: 91-98, 1981]. Using in situ hybridization, we have demonstrated that both the N-myc and IGF-II genes are coordinately overexpressed in nearly all AHFs in precancerous woodchuck livers. In contrast, WHV replication was either repressed or undetectable in the same AHFs. The use of probes selective for N-myc 2 versus N-myc 1 (the normal mammalian homologue) revealed nearly exclusive expression of N-myc 2 in AHFs. Cells within AHFs were generally slow growing, as determined by frequency of histone III-expressing hepatocytes; however, a few fast-growing AHFs, with growth rates nearly equivalent to those of HCCs, were identified. Furthermore, very highly elevated N-myc 2 or IGF-II expression was detected in a few subregions within AHFs which otherwise exhibited a uniformly moderate expression, suggesting that selection for higher levels of N-myc or IGF-II expression may occur within AHFs. These data suggest that coordinate expression of N-myc 2 and IGF-II and repression of WHV replication may be functionally involved in the development of AHFs and that cells expressing very high levels of N-myc and IGF-II may be selectively enriched as AHFs progress to HCC, since high levels of N-myc and IGF-II are common in HCCs.
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PMID:Coordinate expression of N-myc 2 and insulin-like growth factor II in precancerous altered hepatic foci in woodchuck hepatitis virus carriers. 848 4

Chronic hepatitis resulting from hepatitis C virus (HCV) infection develops into cirrhosis in at least half of infected patients and increases the risk of hepatocellular carcinoma. The pathogenic effects of a number of viruses result from the disturbance of intracellular signal cascades caused by viral antigens. Therefore, we investigated the interaction of nonstructural protein 3 (NS3) of HCV with the cyclic AMP-dependent signal pathway. We found a similarity between the HCV sequence Arg-Arg-Gly-Arg-Thr-Gly-Arg-Gly-Arg-Arg-Gly-Ile-Tyr-Arg localized in NS3 and the general consensus sequence of protein kinase A (PKA). Consequently, the catalytic (C) subunit of PKA bound to a bacterially expressed fragment of HCV polyprotein containing amino acid residues 1189 to 1525. When this fragment was introduced into cells, it inhibited the translocation of the C subunit into the nucleus after stimulation with forskolin. The result of this inhibition was significantly reduced histone phosphorylation. Therefore, the presence of NS3 in the cytoplasm of infected cells may affect a wide range of PKA functions and contribute to the pathogenesis of the diseases caused by HCV.
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PMID:Nonstructural protein 3 of hepatitis C virus blocks the distribution of the free catalytic subunit of cyclic AMP-dependent protein kinase. 906 Jun 39

The interplay between the acetylation and deacetylation activities within the cell has been postulated to be a mechanism by which the cell regulates expression from genes at the level of chromatin. We have examined the expression pattern of the human histone deacetylase gene HDAC1 and the cyclin dependent kinase inhibitor p57Kip2 in the hepatocellular carcinoma cell line Hep 3B. HDAC1 expression was elevated at low cell densities, but once a critical threshold point in cell density was attained, expression was reduced to very low levels. Treatment of the cells with trichostatin A (TSA), a potent inhibitor of histone deacetylases, was found to affect expression. p57Kip2 was found to be downregulated by TSA, whereas HDAC1 was upregulated. These effects were found to be cell density dependent. The results suggest that HDAC1 plays a role in its own regulation, and that investigations using TSA should be carried out when cells grow exponentially.
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PMID:Effects of cell density and trichostatin A on the expression of HDAC1 and p57Kip2 in Hep 3B cells. 957 Nov 67

Treatment of cells with sodium butyrate is known to increase histone acetylation by inhibiting deacetylases. Here we have observed, in cultured hepatoma cells, that the potent serine-threonine phosphatase inhibitors, okadaic acid or calyculin A, inhibited phosphatase activity and concomitantly decreased the histone acetylation classically maintained by sodium butyrate. These results suggest that a protein phosphatase may mediate the sodium butyrate effect on deacetylases. Since we have previously found that such a protein would also mediate the sodium butyrate effect on gene expression, we propose that a phosphatase activity constitutes an early and essential step in the sodium butyrate-triggered signalling pathway.
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PMID:A protein phosphatase is involved in the inhibition of histone deacetylation by sodium butyrate. 961 85


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