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 objective of this investigation was to throw light on the biological behavior and metabolic regulation of hepatic enzymes of the nonoxidative branch of the pentose phosphate pathway. The activities of transaldolase (EC 2.2.1.2) and trasketolase (EC 2.2.1.1) Were compared in biological conditions that involve modulation of gene expression such as in starvation, in differentiation, after partial hepatectomy, and in a spectrum of hepatomas of different growth rates. The enzyme activities were determined under optimal kinetic conditions by spectrophotometric methods in the 100,000 X g supernatant fluids prepared from tissue homogenates. The kinetic properties of transaldolase and transketolase were similar in normal liver and in rapidly growing hepatoma 3924A. For transaldolase, apparent Km values of 0.13 mM (normal liver) and 0.17 mM (hepatoma) were observed for erythrose 4-phosphate and of 0.30 to 0.35 mM for fructose 6-phosphate. The pH optima in liver and hepatoma were at approximately 6.9 to 7.2. For the transketolase substrates, ribose 5-phosphate and xylulose 5-phosphate, the apparent Km values were 0.3 and 0.5 mM, respectively, in both liver and hepatoma. A broad pH optimum around 7.6 was observed in both tissues. In organ distribution studies, enzyme activities were measured in liver, intestinal mucosa, thymus, kidney, spleen, brain, adipose tissue, lung, heart, and skeletal muscle. Taking the specific activity of liver as 100%, transaldolase activity was the highest in intestinal mucosa (316%) and in thymus (219%); it was the lowest in heart (53%) and in skeletal muscle (21%). Transketolase activity was highest in kidney (155%) and lowest in heart (26%) and skeletal muscle (23%). Starvation decreased transaldolase and transketolase activities in 6 days to 69 and 74%, respectively, of those of the liver of the normal, fed rat. This was in the same range as the decrease in the protein concentration (66%y. In the liver tumors, transaldolase activity was increased 1.5- to 3.4-fold over the activities observed in normal control rat liver. Transketolase activity showed no relationship to tumor proliferation rate. In the regenerating liver at 24 hr after partial hepatectomy, the activity of both pentose phosphate pathway enzymes was in the same range as that of the sham-operated controls. In differentiation at the postnatal age of 5, 12, 23, and 32 days, hepatic transaldolase activities were 33, 44, 55, and 72%, respectively, of the activities observed in the 60-day-old, adult male rat. During the same period, transketolase activ-ties were 18, 21, 26, and 55% of the activities observed in liver of adult rat. The demonstration of increased transaldolase activity in hepatomas, irrespective of the degree of tumor malignancy, differentiation, or growth rate, suggests that the reprogramming of gene expression in malignant transformation is linked with an increase in the expression of this pentose phosphate pathway enzyme...
 ...
PMID:Behavior of transaldolase (EC 2.2.1.2) and transketolase (EC 2.2.1.1) Activities in normal, neoplastic, differentiating, and regenerating liver. 1 80

The effect of bleomycin on [3H]thymidine 5'-triphosphate ([3H]TTP) incorporation into isolated sucrose nuclei from host liver and Morris hepatomas has been compared. Bleomycin stimulates [3H]TTP incorporation 13-fold in host liver and hepatoma 16 nuclei, 8-fold in hepatoma 7800 nuclei, and 3-fold in hepatoma 7777 nuclei. Differences in the nuclear membranes are not responsible for the different response of the nuclei. Nuclei, denuded of their membranes by Triton X-100 treatment, give similar results to sucrose nuclei. Analysis of DNA extracted from liver or hepatoma nuclei incubated with bleomycin indicates that bleomycin produces scissions in the nuclear DNA and that some repair synthesis takes place. Incubation of nuclei with 111indium-labeled bleomycin shows an equal binding capacity of liver and hepatoma nuclei for bleomycin. Bleomycin also stimulates incorporation of [3H]TTP in a system using chromatin or calf thymus DNA as primer. Host liver or hepatoma chromatin incubated with a DNA polymerase extracted from normal rat liver nuclei is stimulated approximately to the same extent by bleomycin. When DNA polymerase extracts from host liver and hepatoma nuclei are assayed with calf thymus DNA as primer, bleomycin has a greater stimulatory effect on [3H]TTP incorporation with host liver DNA polymerase than with hepatoma DNA polymerase in the system. We suggest that a defect in the repair system in hepatoma nuclei is responsible for the relatively lower response to bleomycin.
 ...
PMID:Effect of bleomycin on [3H]Thymidine 5'-Triphosphate incorporation into host liver and hepatoma nuclei. 5 97

We have studied the effects of human alpha-fetoprotein (HAFP), isolated from the serum and ascitic fluid of a hepatoma-bearing patient, on the in vitro transformation of human peripheral blood lymphocytes by a variety of mitogenic stimuli. At a concentration of 2.5 mg/ml, HAFP inhibited the lymphocyte response to phytohemagglutinin, concanavalin A, and rabbit anti-human thymocyte serum, but failed to inhibit the response to pokeweed mitogen. HAFP was able to inhibit the one-way mixed lymphocyte culture at concentrations of 250-500 mug/ml, but failed to inhibit at 100 mug/ml. Exposure of lymphocytes to 2.2 mg/ml of HAFP for 18 hr did not result in significant lymphocytotoxicity, and such cells washed free of HAFP were fully capable of participating in the mixed lymphocyte culture. HAFP did not inhibit lymphocyte E-rosette formation. Fetal HAFP was more effective in inhibiting human lymphocyte responses than hepatoma HAFP. These experiments support the suggestion that HAFP plays an important immunoregulatory role during fetal development, possibly through the suppression of thymus-derived lymphocyte responses to antigenic stimuli; they also suggest that there are important differences in the biological properties of hepatoma and fetal HAFP.
 ...
PMID:Demonstration of the inhibitory effect of human alpha-fetoprotein on in vitro transformation of human lymphocytes. 6 Jul 61

The oxidative phosphorylation and ATPase activity (initial and stimulated by DNP and Mg2+) in tumor mitochondria were investigated. The intact mitochondria of Zajdela hepatoma, in contrast to liver mitochondria, exhibit the ATPase activity which is slightly stimulated by 2,4-dinitrophenol and is markedly activated by Mg2+. The mitochondria from transplantable solid tumors (adenocarcinoma 755, Iensen sarcoma, sarcoma 45) despite satisfactory morphological integrity under electron microscopy are biochemically less intact than the mitochondria of hepatoma. ATPase of these mitochondria is also slightly stimulated by 2,4-dinitrophenol and significantly by Mg2+. The ATPase activity of thymus mitochondria, the normal tissue with sufficiently high proliferative activity, corresponds to that of tumor mitochondria. The total amount of enzyme in mitochondria of tumors investigated and thymus is not lowered, since the ATPase activity in the presence of both DNP and Mg2+ corresponds to the ATPase activity of liver mitochondria. The Mg2+ ATPase activity of tumor mitochondria is not sensitive or is only partly sensitive to oligomycin. The data obtained are indicative of a high lability of the phosphorylating system in tumor and thymus mitochondria. A possibility of reorganization of the energy mechanism of tumor mitochondria and some normal tissues in connection with increased metabolism requiring high energy consumption, is discussed.
 ...
PMID:[Some peculiarities of ATPase in tumor mitochondria]. 15 49

A serum protein present in normal rat serum and absent from the serum of hepatoma-bearing animals at advanced stages has a stimulatory effect on 3H-thymidine incorporation into hepatoma cells in suspension. Liver cells maintained in a similar suspension are not affected by the factor. The stimulation appears to be at the level of chromatin or DNA. Isolated membrane-denuded nuclei from Morris hepatoma 7777 incorporate more 3H-TTP when the factor is present in the incubation mixture. Nuclei from host liver are not stimulated. The factor also stimulates incorporation of 3H-TTP in a system using calf thymus DNA as primer and an extracted DNA polymerase. In this system incorporation is stimulated with DNA polymerase from both tissues, host liver and hepatoma 7777. It is concluded that the factor does not act on the DNA polymerase but on chromatin or DNA.
 ...
PMID:Stimulatory effect of a serum factor on DNA synthesis in isolated hepatoma nuclei. 17 43

Two hundred and seventy-five male CBA/Birmingham mice including 84 mice over 80 wk of age were autopsied at intervals over the whole range of their natural life span of about 2 1/2 yr. Body weight increased progressively up to 30 wk of age when a plateau value of 30-40 g was attained. Subsequent to 80 wk a slight, progressive decrease was observed. The thymus showed a profound increase in size from about 5 mg at birth to approximately 60 mg by the 3rd wk. Thereafter, the weight of the thymus decreased, rapidly at first, to reach 20-30 mg by 15 wk of age. The thymus weight then decreased more slowly to around 10 mg by the 80th wk. The spleen weight reached a plateau value of 50-60 mg by 4 wk and this was maintained until the 80th wk. In mice older than 80 wk varying degrees of splenomegaly were observed. Histologically, the areas of white pulp in these spleens were very prominent, suggestive of an on-going immune response. It was possible to associate this splenomegaly with the appearance of gross and microscopic evidence of hepatomas. No hepatomas were observed prior to 80 wk, but between 80 and 120 wk the incidence increased progressively; and all the mice whose age at autopsy exceeded 120 wk had hepatomas. Histologically the hepatomas showed marked nuclear plemorphism with occasional mitotic figures. Thrombi, areas of avascular necrosis and collections of inflammatory cells were observed. The tumour metastasised to the lung in 12% of cases. The doubling time of the hepatoma in situ was estimated as 1-6 wk (range 1-3-1-8 wk). These hepatomas were transplantable and grew with a doubling of 2-25 wk in syngeneic adult recipients. To test if the more rapid progressive growth of the tumour in situ in old CBA mice might have resulted from a breakdown in "immunological surveillance" the same tumour was transplanted simultaneously to a group of young and old recipients. The tumour grew more slowly (doubling time, 2-5 wk) in the old recipients. This result would not appear to support the hypothesis of a prolonged breakdown of immunological surveillance as the cause of the progressive increase in the incidence and growth of these tumours in situ in old mice.
 ...
PMID:The incidence, pathology and transplantation of hepatomas in CBA mice. 18 43

The behavior of the rate-limiting enzyme of purine catabolism, xanthine oxidase (EC 1.2.3.2); was examined in normal liver, in 17 hepatomas of different growth rates, and in rapidly growing differentiating and regenerating liver. Xanthine oxidase activity was measured in the supernatant fluid prepared by centrifugation of 5% homogenates at 100,000 X g for 30 min. There was no uricase activity in the supernatant fluid. The affinity of xanthine oxidase to xanthine was similar in normal liver and in slow- and rapidly growing hepatomas (Km=6 to 8 muM), and theoptimum pH was 8.0; at pH 7.4, the activity was 80% of that at the pH optimum. A standard assay was worked out for the liver and hepatoma systems; the enzyme activity was linear during 60-min incubation and proportionate with amounts of protein added over a range of 0.5 to 3.0 mg. Xanthine oxidase specific activity was 9 times higher in small intestine than in liver. Activities in lung, spleen, kidney, heart, testes, and thymus were 67, 59, 21, 19, 8, and 8%, and in skeletal muscle, brain, and bone marrow activities were 5% of that of the liver. In regenerating liver, xanthine oxidase activity was not changed from that of the liver of sham-operated controls up to 96 hr after operation. The activity of the average differentiating liver cell was less than 5% of that of adult liver during the first week after birth. At postnatal ages of 18, 25, 30 and 40 days, the activity rose to 18, 46, 76, and 94%, respectively, of that of the adult liver. In starvation, hepatic xanthine oxidase activity per cell was preferentially depleted as compared to the decline in protein concentration. Upon refeeding, the enzymatic activity was restored more slowly than the protein content. Since xanthine oxidase activity was decreased in all examined hepatomas, including the slowest-growing, well-differentiated neoplasms, the altered activity of this enzyme appears to be.linked with neoplastic transformatiobosyl 1-pyrophosphate amidotransferase (EC 2.4.2.14), was increassed in the hepatomas, the reprogramming of gene expression results in an imbalance that favors the synthetic over the catabolic potential. This enzymatic imbalance should confer selective advantages to the cancer cells.
 ...
PMID:Imbalance of purine metabolism in hepatomas of different growth rates as expressed in behavior of xanthine oxidase (EC 1.2.3.2). 18 29

Considerable thymidine kinase and pyrroline-5-carboxylate reductase activities were found in the plasma of rats bearing a transplanted lymphoma; neither activity was detected in plasma of hosts carrying hepatic, renal, mammary, or submaxillary gland tumors. All host livers exhibited signs of biochemical immaturity as indicated by the appropriate increases or decreases in the concentrations of the nine enzymes measured. The extent and time schedule of the changes in host liver varied with the enzyme and with the tumor that caused them. The hepatic concentrations of ornithine aminotransferase, arginase, pyrroline-5-carboxylate reductase, and glucokinase (all diminished), and of peptidyl proline hydroxylase and hexokinase (increased) were sensitive indicators of tumor growth in general. The concentration of ornithine aminotransferase decreased before the tumors became palpable. At more advanced stages, the high hepatic thymidine kinase activity distinguished the presence of hepatoma and lymphoma from those of all other equally fast-growing tumors. However, only in lymphoma-bearing rats did a fivefold elevation of hepatic thymidine kinase occur as early as 4 days after implantation. Additional observations on the lymphoma itself, on blood cells, and on the involuting thymus of normal rats indicate that the striking systemic effects of this tumor cannot be explained by a release of enzymes from the thymus or by the increased number of lymphoma cells present in blood or liver.
 ...
PMID:The effect of lymphoma and other neoplasms on hepatic and plasma enzymes of the host rat. 18 34

The binding of the glucocorticoid receptor-steroid complex from a line of rat hepatoma tissue culture (HTC) cells to DNA has been examined. An equilibrium competition assay involving a constant, low total amount of double-stranded DNA was developed to compare the complex binding ability of DNA free in solution and bound to cellulose. This binding ability is lowered by a factor of five when DNA is associated with cellulose. Similar studies with HTC cell, calf-thymus, and Escherichia coli DNA revealed no difference in the relative number or affinity of binding sites for receptor-steroid complex in each DNA. The synthetic DNA molecules poly[d(A-T)-d(A-T)] and poly[d(G-C)-d(G-C)] bound complexes equally well but less than the three "natural" DNA molecules. This appears to be due to differences in acceptor site affinity and suggests that nucleotide complexity and/or sequence influences the affinity of HTC cell receptor-glucocorticoid complexes for DNA.
 ...
PMID:Glucocorticoid receptor-steroid complex binding to DNA. Competition between DNA and DNA-cellulose. 18 40

Time relationships for recovery of several host organs from toxic effects of 5-fluorouracil were determined in ACI rats bearing Morris hepatoma 3924A. A single injection of 150 mg/kg body weight 5-fluorouracil (the LD10) resulted in loss of 90% of the tibial bone marrow, 60% of the intestinal mucosa, and 90% of the thymus as measured by total DNA content of the organs. Organ DNA contents following 150 mg/kg of the drug were minimal on day 3 for intestine and on day 5 for marrow and thymus. A return to pretreatment or higher levels of DNA was observed by day 4 for intestine, day 11 for tibial marrow, and day 19 for thymus. Incorporation of 3H-deoxyuridine into host organ DNA after 150 mg/kg 5-fluorouracil was inhibited 36 hrs for intestine, 3 days for thymus, and 5 days for tibial bone marrow. Inhibition of 3H-deoxyuridine incorporation into DNA was similar for 50, 100, and 150 mg/kg doses both in tumor and in host organs, but recovery of 3H-deoxyuridine incorporation and DNA content of host organs began later with the higher doses of 5-fluorouracil. Maximal incorporation of 3H-deoxyuridine into DNA was observed on day 4 for intestine, day 8 for marrow, and day 9 for thymus after treatment with 150 mg/kg 5-fluorouracil. Animal lethality following the second of two 150 mg/kg injections of 5-fluorouracil was related to the extent of recovery of intestinal mucosa and bone marrow at the time of the second injection. Survival decreased to 0% for normal rats when the interval between injections was 3-4 days, improved at 5 days and was 100% when the interval was 10-11 days.
 ...
PMID:Differential recovery of intestine, bone marrow, and thymus of rats with solid tumors following 5-fluorouracil administration. 18 99


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