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)

Most patients with hepatocellular carcinoma have an elevated alpha-feto-protein (AFP) level. This high level of AFP expression is transcriptionally controlled by the 5'-flanking sequence of the AFP gene. Using the 5'-flanking sequence as a promoter for the herpes simplex virus thymidine kinase (HSV-TK) gene in an adenoviral vector (Av1AFPTK1), the therapeutic efficacy of adenovirus-mediated HSV-TK gene transduction, followed by ganciclovir (GCV) administration, was studied in tumors in athymic nude mice. Av1AFPTK1 transduction of two cell lines demonstrated HSV-TK enzyme activity only in the AFP-producing cells (HuH7) and not in the AFP nonproducing cells (SK-Hep-1). As expected, only transduced HuH7 cells were killed by GCV treatment. Transduction by an adenoviral vector harboring a Rous sarcoma virus promoter and HSV-TK gene (Av1TK1) showed enzymatic activity and GCV killing in both cell lines. All HuH7 tumors that were transduced with either Av1AFPTK1 or Av1TK1 completely regressed after GCV treatment. On the other hand, there was complete regression of SK-Hep-1 tumors only when treated with Av1TK1 and GCV and not when treated with Av1AFPTK1 and GCV. Thus, cell-specific killing was achieved by adenoviral vector containing AFP promoter for the HSV-TK gene and GCV treatment.
 ...
PMID:Adenovirus-mediated gene therapy of hepatocellular carcinoma using cancer-specific gene expression. 758 89

We have analyzed the ability of a recombinant replication-defective adenovirus to transfer the thymidine kinase gene of herpes simplex virus (HSV-tk) into hepatocellular carcinoma (HCC) cells to confer sensitivity to ganciclovir. Three HCC cell lines (Hep3B, PLC/PRF/5, and HepG2) were efficiently infected in vitro by a recombinant adenovirus carrying lacZ reporter gene (AdCMVlacZ). Expression of HSV-tk in HCC cells infected with a recombinant adenovirus carrying HSV-tk gene (AdCMVtk) induced sensitivity to ganciclovir in a dose-dependent manner. A bystander killing effect was observed when 90% of uninfected tumor cells were mixed with only 10% of AdCMVtk-infected cells. These data show that recombinant adenoviruses are efficient vectors for transduction of drug-sensitizing genes to HCC cells in vitro. We suggest that a gene therapy approach to hepatocellular carcinoma can be established using adenoviral transfer of HSV-tk to tumor cells and subsequent administration of ganciclovir.
 ...
PMID:Induction of sensitivity to ganciclovir in human hepatocellular carcinoma cells by adenovirus-mediated gene transfer of herpes simplex virus thymidine kinase. 760 2

Insulin inhibits the hepatic transcription of insulin-like growth factor binding protein-1 (IGFBP-1). In the present studies, human HEP G2 hepatoma cells were transiently transfected with human IGFBP-1 gene promoter constructs in order to identify cis elements and trans-acting factors that confer the insulin effect. Transfections of IGFBP-1 promoter deletion constructs localized an insulin responsive element (IRE) between approximately 140- and approximately 103-base pair (bp) 5' to the mRNA capsite. This region contains a 25-bp sequence which is 100% conserved in the rat IGFBP-1 promoter and which has two AT-rich, 8-bp elements exhibiting dyad symmetry. Site-directed mutagenesis of both elements in the same 1205-bp IGFBP-1 promoter construct abolished the inhibitory effect of insulin on promoter activity. Also, the native but not the mutant IGFBP-1 IRE conferred the inhibitory effect of insulin to the heterologous thymidine kinase promoter. Gel mobility shift assays identified a DNA binding activity which specifically binds the native IGFBP-1 IRE and which is not altered by prior insulin treatment. The IGFBP-1 IRE sequence is similar to those of functionally mapped IREs from other gene promoters, suggesting that this common IRE and the protein(s) which it binds confer the insulin effect to a number of insulin-sensitive genes.
 ...
PMID:Identification of an insulin-responsive element in the promoter of the human gene for insulin-like growth factor binding protein-1. 768 22

Carbamoylphosphate synthetase I (CbmPS) is first expressed in rat hepatocytes shortly before birth. After birth, expression of CbmPS gradually becomes confined to the hepatocytes surrounding the portal veins. To obtain insight into the spatiotemporal regulation of its expression, the rat CbmPS gene was isolated and characterized. The gene is 110 kb in length and contains 38 exons. The basal promoter comprises the first 161 nucleotides upstream of the transcription-initiation site. Determination of the state of methylation of the 5' portion of the gene identified a CCGG sequence at -6.3 kb that is selectively demethylated in adult tissues which express CbmPS. This site remains methylated before birth, however, despite recruitment of all hepatocytes for CbmPS synthesis, indicating that its demethylation is a consequence of rather than a condition for expression of CbmPS. Transient expression assays revealed that the region surrounding the CCGG site at 6.3 kb functions as an enhancer. In FTO-2B hepatoma cells and Rat-1 fibroblasts, this enhancer is constitutively active when tested in front of the basal viral thymidine kinase promoter. When tested in front of the basal CbmPS promoter in hepatoma cells, however, the activity of this enhancer is dependent on the presence of glucocorticoids. In Rat-1 fibroblasts, the presence of both glucocorticoids and cyclic AMP is required for full activity, suggesting that the hepatocyte-specific expression of CbmPS is related to tissue-specific differences in the sensitivity to cyclic AMP. Matrix-attachment regions (MAR) are present upstream and downstream of the CbmPS gene. The downstream MAR defines the 3' boundary of the gene. The upstream MAR is located midway between the basal promoter and the enhancer, and may function as a hinge point to facilitate the positioning of the enhancer in the vicinity of the basal promoter.
 ...
PMID:Isolation and characterization of the rat gene for carbamoylphosphate synthetase I. 770 49

Elements responsible for the transcriptional activity of the human ATP synthase beta-subunit (ATPsyn beta) gene promoter have been studied through transient expression in HepG2 hepatoma cells of a CAT gene connected with various 5'-deletion mutants of the 5'-flanking region. Promoter activity was mostly dependent upon a single CCAAT motif as well as a nearby Ets domain binding region. This last region contains two sites that bind Ets-related proteins present in liver nuclear extracts as well as recombinant purified Ets-1 protein. The ATPsyn beta promoter was trans-activated by Ets-1 and Ets-2 expression vectors, and this effect was lost when the Ets binding region was deleted. The Ets binding region of the ATPsyn beta promoter increased basal expression and conferred Ets-1- and Ets-2-dependent trans-activation to the herpes symplex thymidine kinase minimal promoter. A double-point mutation of the main Ets-binding site, which suppresses Ets binding, blocks Ets-dependent trans-activation. It is concluded that the gene for the mitochondrial ATPsyn beta is a target of transcriptional activation by members of the Ets family of transcription factors. It is suggested that Ets transcription factors may be involved in the enhanced expression of the ATPsyn beta gene in highly proliferating cells and in the coordinate transcription of nuclear genes for mitochondrial proteins.
 ...
PMID:ETS transcription factors regulate the expression of the gene for the human mitochondrial ATP synthase beta-subunit. 779 71

We constructed a recombinant adenovirus carrying the firefly luciferase gene driven by the thymidine kinase promoter and controlled by the palindromic thyroid hormone/retinoic acid-responsive element. The same adenovirus vector without the hormone-responsive element was used as control. Regulation of the luciferase gene expression was tested in pituitary-derived GH cells and hepatoma-derived HepG2 cells infected with the recombinant adenoviruses. Administration of triiodothyronine to GH cells and all-trans-retinoic acid to HepG2 cells resulted in 8.0 +/- 0.3-fold and 4.6 +/- 0.5-fold induction of luciferase activity, respectively. No significant increase was observed with the control adenovirus. Hormonal regulation was also examined in adult mice. Mice depleted of thyroid hormone were injected intravenously with the recombinant adenoviruses and given 4 times the replacement dose of triiodothyronine or vehicle only for 4 days. Hormone administration resulted in 4.2-fold increase of luciferase activity in liver homogenates. No significant effect was observed in animals injected with the control adenovirus. This recombinant adenovirus provides a new experimental system in the study of thyroid hormone and retinoic acid action and offers the potential to regulate by physiological means the expression of genes transferred for the purpose of therapy.
 ...
PMID:Expression of a thyroid hormone-responsive recombinant gene introduced into adult mice livers by replication-defective adenovirus can be regulated by endogenous thyroid hormone receptor. 792 32

Transforming growth factor alpha (TGF alpha) overexpression is associated with human hepatocellular carcinoma and with transformation of rat liver epithelial cell lines. In transgenic mice TGF alpha overexpression in the liver induces hepatocyte proliferation and leads to the development of tumors. Using a transformed rat liver epithelial cell line which can give rise to hepatocellular carcinomas, we used antisense genes to examine the importance of TGF alpha in tumor growth. Two different rat TGF alpha complementary DNA fragments were cloned in the antisense orientation into a thymidine kinase minigene downstream of a retroviral long terminal repeat. Cell lines that stably expressed the more effective construct, which contained a fragment that spanned the TGF alpha start codon, exhibited a 4-fold reduction in TGF alpha secretion relative to cell lines that expressed the thymidine kinase minigene alone. Following introduction into nude mice of 2 x 10(5) cells the control cell lines grew rapidly to produce large, highly cellular tumors by 5-6 weeks following injection, whereas with the antisense cell lines tumor growth was delayed so that tumors needed an additional 5 weeks to reach the same size. A high level of growth inhibition was also evident following injection of 2 x 10(6) cells, although the delay in tumor growth from antisense lines was shortened to about 3 weeks. Furthermore, tumors produced by 3 of the 4 antisense cell lines tested were fibrotic and hypocellular relative to those produced by the control cell lines. Growth of tumors from the antisense cell lines was associated with a decline in antisense RNA expression. In contrast, tumors generated from the control cell lines maintained high levels of expression of the control thymidine kinase minigene. These data demonstrate that tumor growth from highly tumorigenic liver cells can be inhibited by disrupting their ability to produce TGF alpha.
 ...
PMID:Inhibition of tumor growth in liver epithelial cells transfected with a transforming growth factor alpha antisense gene. 803 55

Transcription of the phosphoenolpyruvate carboxykinase gene is stimulated by glucocorticoids, retinoic acid, and cAMP and is dominantly inhibited by insulin and phorbol esters. The glucocorticoid response is mediated by a complex regulatory unit that consists of two glucocorticoid receptor (GR) binding sites (GR1 and GR2) and two adjacent accessory factor elements (AF1 and AF2). Deletion of either the AF1 or the AF2 element results in a 50-75% reduction of the glucocorticoid response. In addition to their accessory role in glucocorticoid action, the AF1 and AF2 elements mediate retinoic acid and insulin/phorbol ester effects, respectively. Site-directed mutagenesis was performed on AF1 and AF2 to precisely locate the sequences responsible for accessory activity in each element. The glucocorticoid accessory activity of the AF1 element maps to the same 12-base pair sequence (TGACCTTTGGCC) involved in the response of the PEPCK gene to retinoic acid. The glucocorticoid accessory activity of the AF2 region maps to the same 10-base pair sequence (TGGTGTTTTG) responsible for mediating the insulin and phorbol ester responses through this element. The AF1 and AF2 elements bind different sets of nuclear proteins, and this binding is not qualitatively or quantitatively affected by treatment of the rat H4IIE hepatoma cells with retinoic acid (AF1) or insulin (AF2). AF2 functions in a heterologous context (a consensus glucocorticoid response element and the thymidine kinase promoter), whereas AF1 functions in this context only if the retinoic acid receptor is overexpressed in the cells. These results show that the AF1 and AF2 elements affect the glucocorticoid response through different protein DNA interactions, and that a small sequence in each serves multiple functions. Together with GR1 and GR2, they form a complex hormone response unit which provides an integrated response of the phosphoenolpyruvate carboxykinase gene to a variety of positive and negative signals.
 ...
PMID:Integration of multiple signals through a complex hormone response unit in the phosphoenolpyruvate carboxykinase gene promoter. 805 68

Tyrosine aminotransferase gene expression is confined to parenchymal cells of the liver, is inducible by glucocorticoids and glucagon, and is repressed by insulin. Three enhancers control this tissue-specific and hormone-dependent activity, one of which, located at -11 kb, is implicated in establishing an active expression domain. We have studied in detail this important regulatory element and have identified a 221-bp fragment containing critical enhancer sequences which stimulated the heterologous thymidine kinase promoter more than 100-fold in hepatoma cells. Within this region, we have characterized two essential liver-specific enhancer domains, one of which was bound by proteins of the hepatocyte nuclear factor 3 (HNF3) family. Analyses with the dedifferentiated hepatoma cell line HTC suggested that HNF3 alpha and/or -gamma, but not HNF3 beta, are involved in activating the tyrosine aminotransferase gene via the -11-kb enhancer. Genomic footprinting and in vitro protein-DNA binding studies documented cell-type-specific binding of ubiquitous factors to the second essential enhancer domain, which by itself stimulated the thymidine kinase promoter preferentially in hepatoma cells. These results will allow further characterization of the role of these enhancer sequences in developmental activation of the tyrosine aminotransferase gene.
 ...
PMID:The distal enhancer implicated in the developmental regulation of the tyrosine aminotransferase gene is bound by liver-specific and ubiquitous factors. 810 32

Angiotensinogen is shown to be produced by the liver and the hepatoma cell line HepG2. As a first step for understanding the molecular relationship between the transcriptional regulation of the angiotensinogen gene and the pathogenesis of hypertension, we have analyzed the basal promoter of the angiotensinogen gene. Chloramphenicol acetyltransferase (CAT) assays with 5'-deleted constructs showed that the proximal promoter region from -96 to +22 of the transcriptional start site was enough to express HepG2-specific CAT activity. Electrophoretic mobility shift assay and DNase I footprinting demonstrated that the liver- and HepG2-specific nuclear factor (angiotensinogen gene-activating factor [AGF2]) and ubiquitous nuclear factor (AGF3) bound to the proximal promoter element from -96 to -52 (angiotensinogen gene-activating element [AGE2]) and to the core promoter element from -6 to +22 (AGE3), respectively. The site-directed disruption of either AGE2 or AGE3 decreased CAT expression, and the sequential titration of AGF3 binding by in vivo competition remarkably suppressed HepG2-specific CAT activity. Finally, the heterologous thymidine kinase promoter assay showed that AGE2 and AGE3 synergistically conferred HepG2-specific CAT expression. These results suggest that the synergistic interplay between AGF2 and AGF3 is important for the angiotensinogen promoter activation.
 ...
PMID:Molecular mechanism of transcriptional activation of angiotensinogen gene by proximal promoter. 816 41


<< Previous 1 2 3 4 5 6 7 8 9 10 Next >>