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 ascites form of a chemically induced guinea pig hepatoma, line-10, was resistant to killing in vitro by xenogeneic antibody and guinea pig complement. Pretreatment of line-10 cells with certain proteolytic enzymes rendered tham susceptible to the killing action of antibody and guinea pig complement. The effects of enzyme pretreatment were dependent on enzyme concentration, temperature, and could be blocked by addition of competitive or non-competitive inhibitors. The effect of the enzyme treatment could reversed by incubating the treated cells at 37 degrees C (but not at 0 degrees C), in the absence of the enzyme. Effective enzymes included ficin, bromelain, pronase, elastase, papain, trypsin, collagenase, lipases type I and type VI, and the neuraminidase preparation isolated from Clostridium perfringens. The activity of the lipase preparations and the neuraminidase preparation isolated from Clostridium perfringens appeared to be caused by proteolytic enzyme contamination. Enzyme preparations that proved ineffecitve in rendering the line-10 cells sensitive to killing by antibody and guinea pig complement included DNase, RNase, beta-glucuronidase type 6A or type B10, hyaluronidase type V or type VI, and pectinesterase.
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PMID:Lysis of tumor cells by antibody and complement. VI. Enhanced killing of enzyme-pretreated tumor cells. 17 70

We have studied the effects of triiodothyronine (T3) on the production of hepatic triacylglycerol lipase (HTGL) in the human hepatocellular carcinoma cell line, HepG2, by measuring its activity and mRNA levels. The HTGL activity released into the medium by heparin, increased after the addition of T3 in a both time- (27% increase after 24 and 75% increase after 48 h) and dose-dependent manner (maximum activity with over 0.2 micrograms/ml of T3 in the medium). Messenger RNA levels of HTGL in cells incubated with T3 for 24 and 48 h were increased by 33% and 98% compared to those of the control. These results suggest that the production of HTGL may be regulated by thyroid hormone at the level of gene expression.
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PMID:Stimulation of the activity and mRNA level of hepatic triacylglycerol lipase by triiodothyronine in HepG2 cells. 132 33

During lipolysis of chylomicron triacylglycerol by lipoprotein lipase, arachidonic acid (AA) esters are hydrolyzed at a slower rate than the predominant 16-18 carbon fatty acid esters. The further metabolism of the AA that is hereby enriched in the chylomicron remnant acylglycerols has not been investigated. In the present study, we examined the low density lipoprotein (LDL) dependent and independent metabolism of [14C]AA present in chylomicron remnants in the human hepatoma cell line Hep G2. Mesenteric duct cannulated rats were fed [14C]AA and [3H]cholesterol in corn oil, and the chyle obtained was injected intravenously into hepatectomized rats to form chylomicron remnants labeled with [14C]AA in the triacylglycerol (TG) and with 3H in the cholesteryl ester portion. The remnants were then incubated with Hep G2 cells. The uptake of [14C]AA within 2-4 h was similar to that of [3H]cholesteryl ester. After uptake into the cells, [14C]AA was preferentially incorporated into phospholipids, a high proportion being found in phosphatidylcholine, phosphatidylethanolamine and phosphatidylinositol. [14C]AA and [3H]cholesteryl ester uptake were influenced to similar extents by factors unknown to regulate the LDL receptor and by an anti-LDL receptor antibody. Addition of compactin thus increased the uptake of [14C]AA by 50% in 4 h and mevalonolactone decreased the uptake by 86%. Using an anti-LDL receptor antibody, 25.0% of [3H]cholesterol/cholesteryl ester and 37.7% of [14C]AA binding to the cells at 4 degrees C were blocked. There was no lipolysis of [14C]TG or [14C]diacylglycerol by lipase secreted into the medium during incubations.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Lipoprotein receptor mediated metabolism of [14C]arachidonic acid labeled chylomicron remnants by Hep G2 cells. 133 5

A pancreatic carcinoma and liver metastases associated with marked elevation of the serum alpha-fetoprotein (AFP) level were resected from a 57-year-old man. On microscopic examination, the tumor cells showed a predominantly acinar arrangement, with tubular and trabecular structures; in some foci it had features of a medullary pattern. Alpha-fetoprotein, lipase, trypsin, chymotrypsin, and alpha 1-antitrypsin were strongly demonstrated in tumor tissue by immunohistochemical techniques. A biochemical analysis of AFP on affinity sepharose columns revealed that the AFP derived from the tumor tissues was similar to that of hepatocellular carcinoma. Ultrastructural study showed that most of the tumor cells had abundant rough endoplastic reticulum and numerous zymogen granules. No squamoid corpuscles, neuroendocrine granules, bile production, or bile canaliculi were recognized. These findings suggest that this unique tumor originated from acinar cells.
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PMID:Alpha-fetoprotein-producing acinar cell carcinoma of the pancreas. 137 64

A two-cycle immunoprecipitation procedure is described that markedly reduces nonspecific protein contamination occurring during the precipitation of hepatic lipase from rat H4 hepatoma cells. In this method, the precipitation of immune complexes during both cycles is achieved by utilizing a sodium dodecyl sulfate (SDS)-washed preparation of lyophilized Staphylococcus aureus cells (Staph A); this washed preparation effectively removes Staph A contaminants without compromising the ability to bind immune complexes. Following initial immunoprecipitation of the antigen, the Staph A/IgG/antigen complex containing coprecipitated nonspecific proteins was dissociated with SDS. Triton X-100 was added to the dissociated immunoprecipitate at a concentration (by weight) of at least 5 parts Triton X-100 to 1 part SDS. A second cycle of immunoprecipitation was then initiated by addition of fresh antibody, followed by Staph A precipitation of immune complexes and analysis by SDS-polyacrylamide gel electrophoresis. The two-cycle procedure is shown to be reproducible and suitable for the quantitative determination of relative amounts of hepatic lipase. The procedure described here is generally applicable to the immunoprecipitation of other antigens.
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PMID:A two-cycle immunoprecipitation procedure for reducing nonspecific protein contamination. 175 Jun 92

Serum low-density lipoprotein (LDL) concentration is a major determinant of susceptibility to the development of atherosclerosis. A major component of the protein moiety of LDL and its precursor very-low-density lipoprotein is apolipoprotein B (apo B). The human hepatoma cell line, Hep G2, was used as a model for the investigation of mechanisms which control hepatic secretion of the apo B and lipid components of lipoproteins. Using a sensitive immunoradiometric assay for apo B developed in this laboratory, we showed that bovine serum albumin inhibited and glucose, and fatty acids enhanced the rate of accumulation of apo B in the culture medium of Hep G2 cells. However, these substances did not necessarily affect LDL lipids in the same way as apo B. This finding appeared to be due to Hep G2 cells expressing lipase activities which led to triacylglycerol and phospholipid hydrolysis and lipid reuptake. Reuptake of apo B also occurred, but its rate of accumulation in the culture medium suggested it was a closer reflection of its true secretory rate.
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PMID:Lipoprotein secretion by the human hepatoma cell line Hep G2: differential rates of accumulation of apolipoprotein B and lipoprotein lipids in tissue culture media in response to albumin, glucose and oleate. 195 47

Chemical analysis of ascitic fluid may be helpful in determining the underlying disease. We discuss the diagnostic accuracy of the common and newer chemical parameters (protein, LDH, lactate, glucose, cholesterol, triglycerides, phospholipids, fibronectin, albumin gradient [value of serum minus value of ascites], ferritin, tumor markers, immunomodulators, leukocytes, bacterial and cytologic examinations). We also review the pathogenesis and clinical findings of the most frequent ascites forms (benign hepatic, infective, malignant ascites, ascites associated with liver metastases or hepatocellular carcinoma, cardiac and pancreatic ascites) and the most important diagnosis criteria. In the malignant ascites a high cholesterol, a narrow albumin gradient or a high ferritin value have high diagnostic accuracy, but diagnosis is by the finding of malignant cells. For the diagnosis of infective ascites, bacteriology is mandatory even though the results are negative in most cases, particularly in spontaneous bacterial peritonitis where diagnosis has to be established clinically, by a low pH or by a high leukocyte count. Benign hepatic ascites is diagnosed by demonstrating an underlying chronic liver disease and laboratory examinations of the peritoneal fluid to exclude other causes. The laboratory tests in ascites associated with liver metastases or with hepatocellular carcinoma were similar to those in benign hepatic ascites and the two ascites forms must be separated by other clinical and technical findings. Pancreatic ascites can easily be distinguished from the other forms by the high amylase and lipase content.
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PMID:[Laboratory chemical analysis in ascites]. 203 10

The culture fluid of Hep G2 human hepatoma cells contains triglyceridase activity resistant to high-salt concentrations. The lipase binds to Sepharose-heparin columns from which it can be eluted by 0.8 to 0.9 M NaCl. The nature of this lipase was studied using antibodies raised against "liver" lipases from human and rat origin. The anti-rat liver lipase inhibits both the postheparin human and rat plasma enzyme while the anti-human liver lipase has no effect on the rat enzyme. The lipase of the Hep G2 cultures showed affinity to the antibodies raised against rat as well as human "liver" lipase as shown by inhibition experiments. These results show that Hep G2 cells secrete "liver" lipase and that there seems to exist a structural homology between the lipases from rat and human origin.
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PMID:Human hepatoma (Hep G2) cultures contain salt-resistant triglyceridase ("liver lipase"). 241 21

Monoclonal antibodies against human alpha-fetoprotein (AFP) were obtained by the hybridoma technique and studied with regard to their reactivities with the human hepatoma cell lines PLC/PRF/5 and KN, and a spontaneously immortalized cell line derived from fetal liver, NuE, all of which synthesize AFP. One of the monoclonal antibodies, 19F12 (IgG2b) became bound to free AFP which was used as the immunogen with an affinity constant of 3.4 X 10(8) M-1. This value was not much higher than those of two other antibodies, 19B1 (IgG1) and 9D12 (IgG2b). However, only antibody 19F12 showed definite reactivity with AFP-producing cells in analysis using flow cytometry. Immunofluorescence microscopy showed that antibody 19F12 detected AFP over the surface of NuE and PLC/PRF/5 cells with a uniform distribution, whereas definite reactivities of antibodies 19B1 and 9D12 to these cells were not detected. These antibodies did not show the specific binding to a non-AFP-producing human lung cancer cell line, PC-9, or to human peripheral blood lymphocytes. The binding ability of 19F12 to hepatoma cells was shown in both viable and fixed cells. Addition of free AFP inhibited the binding of antibody 19F12 to PLC/PRF/5 cells in a concentration-dependent manner. The specific reactivity of 19F12 to human AFP was also confirmed by immunostaining of a tissue section of human cancer proved to be AFP positive with AFP-specific antisera. In two-dimensional polyacrylamide gel electrophoresis of the antigen (from membrane fraction of PLC/PRF/5 cells)-antibody (19F12) complex, spots derived from the antibody and a spot (pI 4.7, Mr 65,000) corresponding in pI and molecular weight to AFP were detected. Western blot analysis showed that material in the membrane fraction of PLC/PRF/5 cells recognized by antibody 19F12 has the same molecular weight as human AFP derived from placenta. In a study of reactivities to PLC/PRF/5 cells treated with various enzymes, the reactivity of this antibody decreased when cells were treated with protease and trypsin and increased when lipase was used. The binding of 19F12 to AFP was not inhibited by concanavalin A. The antibody 19F12 appeared to recognize an epitope that is considered to be part of the peptide area of AFP. These results indicate that the reactivity, the amount of bound antibodies, and the distribution of monoclonal antibodies on antigen-producing cells vary, respectively, even though these antibodies were produced using the same antigen as an immunogen.(ABSTRACT TRUNCATED AT 400 WORDS)
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PMID:Detection of membrane-bound alpha-fetoprotein in human hepatoma cell lines by monoclonal antibody 19F12. 246 75

A triacylglycerol lipase was isolated from the culture medium of HepG2 human hepatoma cells and its properties were compared to hepatic triglyceride lipase (H-TGL) from human postheparin plasma. The HepG2 cell enzyme bound to heparin-Sepharose, was eluted with 1 M NaCl and was not inhibited by 1 M salt. Western-blotting of the fractions from the heparin-Sepharose column with a monoclonal antibody prepared against postheparin plasma H-TGL and which binds to an epitope in the carboxyl-terminus of H-TGL gave a single immunoreactive protein band of 65 kDa. This finding of immunochemical identity was confirmed with polyclonal antibodies prepared against synthetic peptides of H-TGL corresponding to amino acid residues 82-94 near the amino-terminus and residues 468-477, the carboxyl-terminus of the enzyme. We conclude that HepG2 cells secrete a single triacylglycerol lipase with molecular weight properties and immunological characteristics identical to post-heparin plasma H-TGL.
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PMID:Human hepatoma (HepG2) cells secrete a single 65 K dalton triglyceride lipase immunologically identical to postheparin plasma hepatic lipase. 247 34


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