Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound   Target Concepts: 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)

We previously identified a naturally occurring peptide fragment derived from the carboxyl terminal region of the E-domain of pro-insulin-like growth factor II (proIGF-II117-156) in medium conditioned by cultured BRL-3A rat liver cells. In the present study we utilized a radioimmunoassay (RIA) for this peptide to measure physiological concentrations of the peptide in media and serum. Serum levels of the E-domain peptide were very high in the 5-day neonatal rat and declined thereafter to reach low levels in adult rat serum. Chromatography of adult rat serum on Sephadex G-75 in 1 M acetic acid yielded a single broad peak of E-peptide immunoreactivity that coeluted with a synthetic E-peptide standard. However, chromatography of day 5 neonatal rat serum on Sephadex G-75 yielded two peaks of immunoreactivity. One of the peaks coeluted with a synthetic E-peptide standard, whereas the other peak eluted in a region where higher molecular weight proteins typically elute. Experiments aimed at determining whether adult rat serum contained a binding protein for the E-domain peptide revealed that: (1) serum contains little, if any, binding protein for the E-domain peptide, (2) serum contains a proteinase activity that degrades the E-domain peptide, and (3) the proteinase activity can be eliminated by acetic acid/ethanol extraction. Of several rat cell lines tested (BRL-3A, rat embryo fibroblasts (REF), hepatoma cell lines (H4, HTC), GH3 pituitary tumor cells, and normal rat kidney fibroblasts (NRK], only BRL-3A and REF cells secreted measurable E-domain peptide into the medium. In addition, it was found that some component(s) of serum could stimulate secretion of E-domain peptide from BRL-3A and REF cells. Chromatography of the immunoreactivity from BRL-3A and REF-conditioned media on Sephadex G-75 in 1 M acetic acid yielded a single peak that coeluted with a synthetic E-domain peptide standard. Since secretion of the E-domain peptide parallels the expression of IGF-II, the RIA for the proIGF-II E-domain peptide may be useful for studies of the biosynthesis and secretion of IGF-II under different physiological conditions. The RIA for the IGF-II E-domain peptide has two technical advantages over the RIA for IGF-II, namely, the lack of interference by IGF binding proteins and the relative ease with which large quantities of pure antigen can be synthesized.
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PMID:The E-domain peptide of rat pro-insulin-like growth factor II (proIGF-II): properties of the peptide in serum and production by rat cell lines. 229 41

A protein preparation that specifically binds insulin-like growth factors (IGFs) I and II was purified from medium conditioned by rat liver BRL-3A cells using molecular sieve chromatography in 1 M acetic acid followed by affinity chromatography on IGF-II-agarose. The affinity-purified IGF-binding protein exhibits a single major band with apparent Mr = 36,300 under reducing conditions on sodium dodecyl sulfate-polyacrylamide gels. The IGF-binding protein is efficiently and specifically cross-linked to either 125I-IGF-I (human) or 125I-IGF-II (rat) using disuccinimidyl suberate. An IGF-binding protein of similar apparent molecular weight was also affinity purified from rat hepatoma H-35 cell conditioned medium and found to differ from the BRL-3A protein such that potent polyclonal antisera prepared in rabbits against the purified BRL-3A IGF-binding protein exhibited a much lower titer for the H-35 protein in an enzyme-linked immunosorbent assay and upon immunoblotting. In order to determine whether a single BRL-3A IGF-binding protein is present in the affinity-purified preparation, the protein was prepared for sequencing on a Sephacryl S-300 column in 6 M guanidine HCl after reduction and alkylation. The amino acid composition (expressed in percentages) of this IGF-binding protein was determined to be: Cys = 5.5, Lys = 4.8, His = 2.8, Arg = 7.8, Asx = 10.2, Thr = 5.1, Ser = 3.9, Glx = 15.7, Gly = 17.4, Ala = 7.3, Val = 4.6, Met = 1.4, Ile = 2.4, Leu = 8.3, Tyr = 1.0, Phe = 1.9. Sequencing of the NH2-terminal portion of this protein led to the identification of 31 amino acids in the following order: Phe-Arg-Cys-Pro-Pro-Cys-Thr-Pro-Glu-Arg-Leu-Ala-Ala-Cys-Gly-Pro-Pro-Pro- Asp-Ala-Pro-Cys-Ala-Glu-Leu-Val-Arg-Glu-Pro-Gly-Cys. We conclude that rat liver BRL-3A cells secrete a single major IGF-binding protein capable of binding both IGF-I and IGF-II.
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PMID:Purification and amino-terminal sequence of an insulin-like growth factor-binding protein secreted by rat liver BRL-3A cells. 242 67

The primary structure of an insulin-like growth factor (IGF) binding protein produced by human HEP G2 hepatoma cells has been deduced from the cDNA sequence. The 234 amino acid protein has a predicted molecular mass of 25,274 and contains a single, distinctive cysteine-rich region. The N-terminal sequence of this protein is quite similar to the limited sequence data available for a rat IGF binding protein produced by BRL-3A cells and suggests a common ancestral origin. In contrast, the HEP G2 IGF binding protein sequence bears no similarity to the N-terminal 15 amino acids of a 53 kilodalton binding protein purified from human plasma. Comparison of full-length protein sequences for the IGF-I and IGF-II receptors with that of the HEP G2 IGF binding protein also fails to demonstrate any significant similarities among these three proteins, and suggests that each contains a unique binding domain for the IGF peptides.
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PMID:Insulin-like growth factor (IGF) binding protein complementary deoxyribonucleic acid from human HEP G2 hepatoma cells: predicted protein sequence suggests an IGF binding domain different from those of the IGF-I and IGF-II receptors. 245 22

The insulin-like growth factors (IGFs) found in plasma and a variety of other body fluids are complexed to specific binding proteins (BPs). The cDNA for a 25K IGF-BP was recently cloned and sequenced, and the primary structure of the BP deduced. This BP is found in amniotic fluid, decidual tissues, conditioned medium from HepG2 human hepatoma cells, and fetal plasma. An additional small IGF-BP has been identified in human cerebrospinal fluid (CSF). We now demonstrate that the IGF-BP found in CSF is structurally and immunologically distinct from that found in HepG2 conditioned medium. While the latter BP has approximately equal affinities for IGF-I and -II, the CSF BP has a 10- to 20-fold greater affinity for IGF-II. In affinity cross-linking studies under reducing conditions, the CSF BP had an apparent mol wt (Mr) of 32,000, while the HepG2 BP migrated as a doublet, with apparent Mr values of 30,000 and 28,000. On Western ligand blots, CSF BPs migrate as five discrete bands, with the most prominent band at an apparent Mr of 34,000, while HepG2 medium yielded a single band at an apparent Mr of 30,000. A polyclonal antibody developed against the human amniotic fluid BP immunoprecipitated the HepG2 BP and reacted with both the HepG2 and amniotic fluid BPs on Western blots, but failed to react with the CSF BP. These data indicate that the CSF and amniotic fluid/HepG2 BP are structurally and immunologically distinct small IGF-BPs.
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PMID:Structural and immunological comparison of insulin-like growth factor binding proteins of cerebrospinal and amniotic fluids. 246 4

Insulin-like growth factor II is secreted primarily by the liver and is reported to be transcribed in many primary hepatocellular carcinoma (PHC) cell lines. We have studied diagnostic significance of serum IGF-II in chronic liver diseases using specific enzyme immunoassay. Serum IGF-II levels (mean +/- SE) were decreased in chronic hepatitis (538 +/- 51 ng/ml; N = 29), liver cirrhosis (427 +/- 45; 50) and PHC (260 +/- 41; 17) compared to controls (830 +/- 49; 57). Serum IGF-II was not different from controls in any of nonhepatic diseases such as diabetes (1032 +/- 97; 19) pancreatic cancer (1413 +/- 282; 8), chronic pancreatitis (999 +/- 126; 17), peptic ulcer (1186 +/- 43; 11), irritable bowel syndrome (1002 +/- 109; 12), gastrointestinal tract cancer (1250 +/- 216; 21) and chronic renal failure (733 +/- 135; 14). In liver diseases serum IGF-II showed a significant correlation with liver function test (negative with retention of indocyanine green and total bile acids; positive with albumin, thrombo-test, and cholinesterase). These results suggest that serum IGF-II reflects a reduced production of IGF-II in the liver and that it can be an index for the residual capacity of liver function.
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PMID:Serum insulin-like growth factor II in chronic liver disease. 253 15

Insulin and insulin-like growth factor (IGF)-I inhibit intracellular protein degradation in a variety of different cell types. In the present studies, the IGF-I-induced inhibition of protein metabolism in Chinese hamster ovary (CHO) cells was found to be blocked by polyclonal antibodies to the IGF-II/mannose-6-phosphate phosphate (Man-6-P) receptor, but not by control immunoglobulin. In contrast, these antibodies had no effect on the ability of IGF-I to stimulate glucose uptake in the same cells. The antibodies to the IGF-II/Man-6-P receptor also inhibited the effect of IGF-I and insulin on protein catabolism in human foreskin fibroblasts and human hepatoma cells, respectively. Moreover, CHO cells overexpressing a cDNA coding for the IGF-II/Man-6-P receptor were found to exhibit an increased effect of insulin on protein catabolism. In contrast, the insulin stimulation of glucose uptake is the same in these transfected cells as in the parental CHO cells. These results implicate the IGF-II/Man-6-P receptor in the insulin- and IGF-I-induced inhibition of protein catabolism.
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PMID:A role for the insulin-like growth factor II/mannose-6-phosphate receptor in the insulin-induced inhibition of protein catabolism. 254 2

We have previously reported that insulin induces a complete and reversible desensitization to the induction of tyrosine aminotransferase by insulin and insulin-like growth factors (IGFs) in HTC rat hepatoma cells. This loss of responsiveness cannot be accounted for by down-regulation of cell surface receptors, but occurs at a postbinding step in hormone action. Here we present evidence that IGF-I and IGF-II also induce desensitization to the actions of both IGFs and insulin and that this effect is mediated by IGF receptors. First, the concentration dependence for this effect is similar to that for the IGF-I and IGF-II induction of tyrosine aminotransferase, which has been shown to be mediated by IGF receptors. Second, antibody to the insulin receptor, which blocks insulin, but not IGF-II, binding to HTC cells, causes a rightward shift in the concentration dependence for insulin induction of desensitization, but does not significantly change the concentration dependence for IGF-II. These results indicate that IGF-II-induced desensitization to IGF-II is not mediated by the insulin receptor, but presumably by an IGF receptor. Although the IGFs do cause a moderate decrease in the binding of IGFs and insulin (to approximately 50-75% of the control value), this cannot account for the virtually complete desensitization to their actions. We conclude that IGFs, like insulin, induce a nearly complete loss of responsiveness to insulin and IGFs, that this effect is mediated via IGF receptors, and that desensitization occurs at a step distal to hormone binding which may be common to the actions of insulin and the IGFs.
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PMID:Regulation of insulin and insulin-like growth factor (IGF) responsiveness by IGFs in rat hepatoma cells. 287 Sep 17

We have used H-35 rat hepatoma cells to test whether the type II insulin-like growth factor (IGF) receptor mediates metabolic responses to IGF-II. On the basis of both affinity cross-linking experiments and competition binding experiments, H-35 cells display insulin and type II IGF receptors, but not type I IGF receptors. IGF-II and multiplication-stimulating activity (MSA; the rat homolog of IGF-II) stimulate tyrosine aminotransferase, amino acid transport, and glycogen synthase activities to the same magnitude as insulin. However, MSA and IGF-II stimulate these metabolic responses only at high concentrations, indicating that these peptides are acting through the insulin receptor. Incubation of H-35 cells with MSA also induces a state of unresponsiveness to the further actions of both MSA and insulin. There is no associated loss of either insulin or IGF-II binding, indicating that desensitization occurs at a postbinding step in hormone action. The high concentration of MSA necessary to induce desensitization is also consistent with MSA acting through the insulin receptor. We conclude that in H-35 cells, the insulin receptor, rather than the type II IGF receptor, mediates the metabolic responses stimulated by MSA and IGF-II as well as the MSA-induced desensitization to insulin and MSA action.
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PMID:Mediation of insulin-like growth factor actions by the insulin receptor in H-35 rat hepatoma cells. 287 66

A growth hormone-dependent binding protein for insulin-like growth factors (IGF-I and IGF-II) has been isolated from human plasma. Analyzed on SDS gels, the preparation contained a major protein band of 53 kDa, and a minor band of 47 kDa. After transfer to nitrocellulose, both species bound iodinated IGF-I, and could be detected using an antibody raised against the purified preparation. In contrast, an IGF binding protein purified from human amniotic fluid bound IGF-I but was not detectable immunologically. The amino acid comparison of the plasma binding protein preparation was different from that reported for amniotic fluid and HEP G2 hepatoma proteins, and the unique amino-terminal sequence, Gly-Ala-Ser-Ser-Ala-Gly-Leu-Gly-Pro-Val-, was different from that of the amniotic fluid and hepatoma proteins. This study indicates that the growth hormone-dependent IGF binding protein of human plasma is structurally and immunologically distinct from other IGF binding proteins.
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PMID:Growth hormone-dependent insulin-like growth factor (IGF) binding protein from human plasma differs from other human IGF binding proteins. 294 61

This study compares the regulation of IGF-II receptors in three rat hepatoma lines, HTC, H-35 and 5123tc, and primary rat hepatocytes. In all cell types [125I]IGF-II bound solely to a species of approximately 250 kDa. Cell surface IGF-II receptors in hepatoma cells had slightly lower affinities (1-2 liters/nmol) than in hepatocytes (4 liters/nmol), but slightly higher IGF-I cross-reactivity (2-4% compared to 1% in hepatocytes). In confluent cultures, the three hepatoma lines expressed 5- to 15-fold more cell-surface receptors per cell than hepatocytes. However, while hepatocyte receptors showed marked inverse density-dependence, increasing over 6-fold between dense (3 x 10(5) cells/3.8 cm2) and sparse (0.16 x 10(5) cells/3.8 cm2) cultures, receptors in all hepatoma lines remained at a constant high level regardless of culture density. These distinct regulatory patterns resemble those described for growth-related functions in hepatocytes and hepatoma cells, and are thus consistent with a role for IGF-II receptors in liver cell proliferation.
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PMID:Differential regulation of insulin-like growth factor-II receptors in rat hepatocytes and hepatoma cells. 296 23


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