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)

The effects of various agents on the binding and degradation of 125I-labelled insulin by isolated rat hepatocytes and cultured H4 hepatoma cells were studied. Various lysosomotropic agents, including chloroquine, ammonium chloride, and the topical anesthetics, lidocaine and procaine inhibited insulin degradation by H4 hepatoma cells but had little effect on the binding of the hormone. Similarly, tosyl-L-lysyl chloromethyl ketone selectively inhibited the degradation of 125I-labelled insulin by isolated hepatocytes, as did the sulfhydryl reagents, p-hydroxy- and p-chloromercuriphenyl sulfonic acid. Inhibitors of energy production, including sodium fluoride, sodium azide, and dinitrophenol, also selectively inhibited the degradation of insulin by hepatocytes, although cyanide had no effect under the conditions used. Lectins and antimicrotubular agents, which are known to affect the mobility of plasma membrane proteins or of intracytoplasmic vesicles, selectively inhibited insulin degradation by hepatocytes to varying degrees, whereas agents which inhibit the function of microfilaments had no effect. At temperatures below 20 degrees C, insulin degradation was negligible but rose rapidly between 20 and 37 degrees C, suggesting that a membrane-related step is rate limiting in the overall degradative process. These results are all consistent with a model of insulin uptake by target tissue involving pinocytosis of receptor-bound hormone followed by intralysosomal degradation.
 ...
PMID:Mode of uptake and degradation of 125I-labelled insulin by isolated hepatocytes and H4 hepatoma cells. 47 1

Line-1 guinea pig hepatoma cells are susceptible to killing by anti-Forssman IgM antibody plus guinea pig complement (GPC). When these tumor cells are incubated with insulin, epinephrine, hydrocortisone, or prednisolone, the cells show a marked reduction in their susceptibility to antibody-C-killing. If the ability of the cells to synthesize DNA, RNA, and protein is impaired by pretreatment with metabolic inhibitors, x-irradiation, or culture in nutrient-deficient media, the hormones are no longer effective in rendering the cells resistant to killing. If only DNA synthesis is impaired, but not RNA and protein synthesis, the hormones are effective. The inability of cells inhibited in their macromolecular synthesis to be rendered resistant to killing after hormone treatment is not due to an inability of the cells to bind hormone.
 ...
PMID:Metabolic requirements for hormone-induced resistance to antibody-complement mediated killing of tumor cells. 89 26

Protein-tyrosine phosphatases (PTPases) play an essential role in the control of signalling through phosphotyrosine pathways. Since little is known about the regulation of these enzymes, we examined the effect of insulin and phorbol 12-myristate 13-acetate (PMA) treatment of well-differentiated rat hepatoma (Fao) cells on the expression of mRNAs encoding three major PTPase homologs in liver: PTPase1B, an intracellular enzyme with a single conserved PTPase domain, and two tandem-domain, transmembrane PTPases, known as LAR and LRP. Treatment of serum-deprived cells with 100 nM insulin increased the abundance of the 4.3 kb and 1.6 kb mRNAs encoding PTPase1B on Northern analysis by 1.6 and 3.1-fold, respectively (p < or = 0.02). Similarly, exposure to 100 ng/ml PMA increased the 4.3 and 1.6 kb PTPase1B mRNAs by 4.5 and 5.7-fold, respectively (p < or = 0.035). In contrast, treatment with insulin or PMA had no significant effect of the abundance of mRNA encoding either LAR or LRP. PMA appeared to have a transcriptional effect on the PTPase1B gene by a protein kinase C-mediated mechanism. The increase in PTPase1B mRNA expression by insulin and PMA suggests that this PTPase may provide feed-back regulation of signalling through the insulin action pathway as well as a potential link between the action of protein kinase C and the regulation of specific phosphotyrosine residues in cells.
 ...
PMID:Differential regulation of mRNAs encoding three protein-tyrosine phosphatases by insulin and activation of protein kinase C. 128 Jan 35

Insulin-like growth factor-binding protein-1 (IGFBP-1) can inhibit or potentiate IGF action. The biological activity of IGFBP-1 is determined by many factors, including its abundance in tissues and plasma, posttranslational modifications, and localization. IGFBP-1 levels in human plasma are highly regulated. They are increased after acute fasting and in diabetes, and are rapidly reversed by refeeding and insulin treatment, respectively. Similarly, IGFBP-1 mRNA is increased in the liver of severely diabetic and ketotic rats and decreased after 4 days of insulin treatment. Insulin rapidly decreases IGFBP-1 mRNA and IGFBP-1 transcription in rat hepatoma cells. The present study asks whether the increase in IGFBP-1 mRNA in diabetic rat liver reflects increased gene transcription, whether insulin decreases IGFBP-1 mRNA through a transcriptional or posttranscriptional mechanism, and whether this decrease is sufficiently rapid to account for the dynamic fluctuations in plasma IGFBP-1. Rats were injected ip with 100 mg/kg streptozotocin and used 7 days later when they were hyperglycemic and failed to gain weight, but were not ketotic. Hepatic IGFBP-1 mRNA levels were 13.6 +/- 5.3-fold greater in diabetic than control liver and decreased to the low levels in nondiabetic controls within 1 h after insulin treatment. In run-on transcription assays, IGFBP-1 transcription was 12.6 +/- 1.5-fold greater in nuclei from diabetic than control liver and decreased to low control levels by 1 h after insulin injection. Normalization of hepatic IGFBP-1 mRNA in insulin-treated diabetic animals did not require restoration of euglycemia. IGFBP-1 mRNA and IGFBP-1 gene transcription also were increased in the kidney of diabetic ketotic rats. We propose that the dynamic regulation of IGFBP-1 gene transcription in diabetes and after insulin treatment, by determining the availability of IGFBP-1 in tissues and plasma, may be a critical factor in the modulation of IGF action.
 ...
PMID:Insulin rapidly decreases insulin-like growth factor-binding protein-1 gene transcription in streptozotocin-diabetic rats. 128 42

Human insulin receptor substrate-1 (hIRS-1) cDNAs were cloned from a lambda GT11 expression library using a monoclonal antibody (MAb) produced against a human hepatocellular carcinoma (HCC) cell line (FOCUS). The predicted amino acid sequence derived from both a genomic DNA fragment and the cDNAs showed a 90.5% identity to the previously reported rat IRS-1 cDNA [Sun, X.P. (1991) Nature 352, 73-77]. Multiple potential phosphorylation sites, that suggest an intrinsic function of this molecule in response to insulin action, were highly conserved between the two species. A c.a. 180 kDa hIRS-1 protein was immunoprecipitated and found to be phosphorylated on tyrosine residue(s) following insulin stimulation of HuH-7 HCC cells. Northern blot analysis demonstrated a single c.a. 5 kb transcript in HCC cell lines and tissues. Higher levels of hIRS-1 gene transcripts were observed in HCC tumors compared to adjacent non-involved normal liver.
 ...
PMID:Cloning and increased expression of an insulin receptor substrate-1-like gene in human hepatocellular carcinoma. 131 24

A soluble construct consisting of a plasmid carrying the gene of the SV40 large T-antigen and an insulin-poly-L-lysine conjugate is able to selectively transfect PLC/PRF/5 human hepatoma cells which possess insulin receptors. Transfection can be efficiently competed by excess free insulin. To examine intracellular transport of the construct, it was fluorescently labeled and its accumulation on and in cells visualized by video-enhanced microscopy and quantitative confocal laser scanning microscopy. After 2 h at 37 degrees C, the labeled construct was found predominantly in intracellular acidic compartments, with a substantial portion of fluorescence localized both near and in the cell nucleus. Binding, endocytosis, and nuclear localization of the labeled conjugate could all be competed by excess free insulin, thus indicating that entry of the conjugate into cells was specifically mediated by the insulin receptor.
 ...
PMID:Receptor-mediated endocytosis and nuclear transport of a transfecting DNA construct. 131 9

Tumor glucose use in patients with non-islet-cell tumors has been difficult to measure, particularly in hepatoma, because of hepatic involvement by neoplasm. We studied a patient with nonhepatic recurrence of hepatoma after successful liver transplantation. Tumor tissue contained messenger RNA for insulin-like growth factor-II (IGF-II), and circulating high molecular weight components and E-peptide of IGF-II were increased. Glucose use measured by isotope dilution with [3-3H]glucose was 7.94 mg/kg fat-free mass per min, and splanchnic glucose production was 0.93 mg/kg fat-free mass per min. Glucose uptake and glucose model parameters were independently measured in tissues by positron emission tomography with 18F-fluoro-2-deoxy-D-glucose. Glucose uptake by heart muscle, liver, skeletal muscle, and neoplasm accounted for 0.8, 14, 44, and 15% of total glucose use, respectively. Model parameters in liver and neoplasm were not significantly different, and glucose transport and phosphorylation were twofold and fourfold greater than in muscle. This suggests that circulating IGF-II-like proteins are partial insulin agonists, and that hypoglycemia in hepatoma with IGF-II production is predominantly due to glucose uptake by skeletal muscle and suppression of glucose production.
 ...
PMID:Glucose utilization in a patient with hepatoma and hypoglycemia. Assessment by a positron emission tomography. 131 26

Experiments with human hepatoma PLC/PRF/5 cells involving the use of two different tests (colony formation and Trypan blue exclusion) have demonstrated a significantly higher photosensitizing activity of chlorin e6 conjugates with bovine serum albumin (BSA) and internalizable ligand insulin as compared to that of chlorin e6 itself. Receptor-mediated internalization of insulin-BSA-chlorin e6 conjugates ensures greater photosensitization of cells than the binding of those conjugates to cell surface receptors. The suitability of such conjugates permitting the delivery of a photosensitizer to most sensitive cell structures is discussed.
 ...
PMID:Internalizable insulin-BSA-chlorin E6 conjugate is a more effective photosensitizer than chlorin E6 alone. 132 Aug 82

Hepatocyte-hepatoma hybrid cells were obtained by fusion of hepatocytes from adult rats and Fao hepatoma cells in the presence of polyethylene glycol. These hybrids were called hepatocytoma cells. The preservation of liver-specific enzyme activities and metabolic functions was studied in the hybrid clone 1E3. 1) The proliferating hepatocytoma cells formed monolayers presenting morphological similarity to primary cultures of hepatocytes. 2) In contrast to Fao hepatoma cells, activities of all gluconeogenic key enzymes were preserved at normal or reduced levels. 3) Lactate-dependent glucose formation was maintained at a state reduced to 36% of the gluconeogenesis in hepatocytes; no glucose formation was detected in Fao hepatoma cells. 4) The activity of the liver-specific glucokinase was reduced in hepatocytoma cells, but it was still present in contrast to Fao cells. The liver-specific isoenzyme pyruvate kinase type L was replaced by the isoenzyme type M2. 5) Gluconeogenic and glycolytic enzyme activities were regulated in hepatocytoma cells by glucagon (0.1 microM) and by insulin (0.1 microM). 6) The genome of hepatocytoma cells and its expression were stable for at least one year, when spontaneously dedifferentiating cells were removed by recloning in hypoxanthine-aminopterine-thymidine (HAT) medium.
 ...
PMID:Hormone-sensitive carbohydrate metabolism in rat hepatocyte-hepatoma hybrid cells. 132 97

We examined the effects of insulin-like growth factors (IGFs) and insulin on erythropoietin (EPO) production by human hepatoma cells (Hep G2). Compared with normoxia (20% O2), EPO production by Hep G2 cells during a 72-h incubation was stimulated fivefold by exposure to low oxygen tension (1% O2) and nearly threefold by exposure to cobalt chloride (100 microM). IGF-I caused a concentration-dependent attenuation of EPO formation under normoxic conditions and inhibited (maximally 50%) EPO production stimulated by either low oxygen tension or cobalt [half-maximal effect (ED50) approximately 5 nM]. The increase of EPO mRNA levels in response to hypoxia was significantly reduced by IGF-I. Similarly to IGF-I, IGF-II (ED50 approximately 8 nM) and insulin (ED50 approximately 80 nM) also inhibited EPO formation in Hep G2 cells. IGF-I (100 pM-100 nM) stimulated the incorporation of radiolabeled alanine as a measure for total protein synthesis, 3H-labeled thymidine incorporation into DNA, and glycogen synthesis at 20 and 1% O2 in a concentration-dependent fashion. IGF-I exhibited a high affinity for the IGF-I receptor (apparent Kd approximately 3 nM). Unlabeled insulin was greater than 100-fold less potent than IGF-I in competing for 125I-IGF-I binding (apparent Kd approximately 360 nM). Conversely, insulin bound to the insulin receptor with high affinity (apparent Kd approximately 0.3 nM), whereas IGF-I was less than 1% as potent in competing for 125I-insulin binding. In summary, IGFs and insulin exert a negative control function on oxygen-regulated EPO production in Hep G2 cells. The inhibitory effect of IGFs and insulin on EPO formation appears to be mediated via the IGF-I receptor.
 ...
PMID:Insulin-like growth factors decrease oxygen-regulated erythropoietin production by human hepatoma cells (Hep G2). 132 19


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