Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UMLS:C0027651 (tumor)
 685,946 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Properties of aryl hydrocarbon hydroxylase in the microsomes were compared between Morris hepatoma 5123D and the host liver from rats bearing this tumor. Requirement of NADPH for the assay of the enzyme activity was observed, compared to that of NADH, and also the additive effect of NADH on the requirement of NADPH was found in the tumor and liver. Curve of pH optimum of the enzyme activity in tumor and liver differed between the rats treated with corn oil and those with 3-methylcholanthrene, indicating a slight shift of the peak value to alkaline pH in the latter. The same values of the apparent Km for NADPH and NADH were shown for the enzyme from the liver and tumor even 24 hr after the treatment with 3-methylcholanthrene, but a difference in the apparent Km for benzo[a]pyrene was demonstrated between the tumor and the host liver, showing 3.6 approximately 6.6 muM in the former and 9.1 approximately 20 muM in the latter. By the addition of 7,8- or 5,6-benzoflavone to the assay medium for the tumor, the induced enzyme was inhibited noncompetitively, and the constitutive enzyme was enhanced, as demonstrated in the host liver. As observed in the induced enzyme in both tissues, cyclohexene oxide and 1,1,1-trichloropropane oxide slightly increased the activity of the constitutive enzyme in the tumor, in contrast to its inhibition in the host liver.
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PMID:Properties of aryl hydrocarbon hydroxylase in microsomes of Morris hepatoma 5123D and the host liver. 0 50

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...
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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

Cultured cells from Morris hepatoma 7316A contained isozymes I and II, but not isozyme III, of branched-chain amino acid transaminase. They also contained tyrosine transaminase. Isozyme II and tyrosine transaminase were induced by addition of cortisol. These findings agree well with in vivo findings. However, prolonged culutre of the cells for over 500 days caused deviation of the chromosomal bumber and activity of both enzymes, and they were no longer affected by cortisol. A tumor formed by back-transplantation of the cells showed the typical isozyme pattern of rapidly growing hepatomas, such as Yoshida ascites hepatomas, i.e., isozymes I and III. These results were discussed in relation to change of gene expression during culture.
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PMID:Isozyme patterns of branched-chain amino acid transminase in cultured Morris hepatoma 7316A. 1 63

Whereas glucocorticoids induce TAT, TRP, GPT in liver and only TAT in HTC cells, no hormonal effect on the synthesis of these enzymes was found in Zajdela hepatoma cells grown in vivo as an ascitic tumor, or in vitro as layer cultures. Although these cells remain uninducible, the hormone penetrates normally, but a strong decrease of the specific binding of cytosol and nuclear proteins with the hormone was observed. The impairment at the level of the hormone receptors could account for the non-inducibility of enzyme synthesis in ZHC cells.
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PMID:Impairment of enzyme induction by glucocorticoids in Zajdela hepatoma cells. 1 35

The Morris hepatoma 5123D after at least two passages in F1 (Buffalo X Wistar) rats shows quicker growth than the original tumor and bearers of it have much lower gamma-glutamyltranspeptidase activity in serum, urine, tumor and in some other organs. This new variant of the hepatoma was labeled as hepatoma 5123D/AS. Simultaneous implantation of hepatomas 5123D/AS and 5123D in the same rats prevents the increase of serum gamma-glutamyltranspeptidase activity. After surgical removal of the former tumor, the enzyme activity in serum quickly increases. No significant differences in some other peptidase activities were observed between the variant and hepatoma 5123D.
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PMID:Effect of passages of Morris hepatoma 5123D in F1 (Buffalo X Wistar) rats on permanent decrease of gamma-glutamyltranspeptidase activity. 1 9

Glucocorticoid-binding macromolecules were examined in Morris hepatomas 7787, 5123tc, 3683F, 7800, and 3683 and the Reuber hepatoma H-35 with the use of the synthetic glucocorticoid, triamcinolone acetonide. The physical properties of the triamcinolone acetonide-binding macromolecules of the hepatomas indicate that they are specific glucocorticoid receptors. The equilibrium association constants (Ka), sedimentation coefficients, and sensitivity to sulfhydryl-blocking reagents were found to be similar when hepatoma receptors were compared with the known properties of the liver receptor. Probably the most convincing criterion that the triamcinolone acetonide-binding macromolecules from the hepatomas are specific receptors is that 50 to 90% of the receptor can be depleted from hepatoma cytosol by treating rats with cortisol. In adrenalectomized tumor-bearing rats, the receptor levels in hepatomas 7787, 7800, 5123tc, and H-35 are comparable to or greater than receptor levels of host liver. However, tryptophan oxygenase was not responsive to glucocorticoids in hepatoma 7800 although receptor levels were quite high, and there were no indications that the receptor molecules were altered. Hepatomas 3683 and 3686F have low levels of receptor which may be related to resistance of these tumors to glucocorticoid treatment.
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PMID:Glucocorticoid receptors in Morris hepatomas and host liver and the correlation of biological activity with receptor levels. 2 Feb 26

The activities of gamma-glutamyl transpeptidase (gamma-GTP), alkaline phosphatase (A-p), and leucine aminopeptidase (LAP) were examined in 18 cases of hepatomas. The activity of gamma-GTP was most remarkable in the hepatoma consisting of small to medium-sized tumor cells showing the least atypism. The enzyme activity found in the type composed of large tumor cells resembled that of normal liver and was considered to be the most mature form of the neoplasm. This enzyme was not found in the immature type composed of small typical tumor cells. A-P activity was seen in only a few cases of hepatoma; conspicuous in one case showing immature features and sporadically in one case with florid histological pattern. The activity of this enzyme could not be confirmed in the type demonstrating marked gamma-GTP activity. LAP activity was noted in the majority of cases, especially marked in the medium-sized tumor cells, but there was hardly any connection between this enzyme and histological type. In general, the cases demonstrating positive gamma-GTP activity tended to show LAP activity. Although the activity of gamma-GTP and that of A-p usually showed an inverse relation, all three enzymes demonstrated almost equal activity in the type showing a florid histological pattern.
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PMID:Enzyme histochemical study on hepatoma--the relation between enzyme activity and histological type. 2 15

Adenylate cyclase activity as well as intracellular content of sAMP were decreased 2.5-4-fold, as compared with normal state, in plasmatic membranes (PM) of hepatoma 22 and of Ehrlich ascites carcinoma--the tumors characterized by high level- of malignancy. Activity of cAMP phosphodiesterase exceeded distinctly the normal value in all the tumors studied. In less malignant hepatoma 48 the adenylate cyclase activity and content of cAMP were similar to those found in normal liver cells. The guanylate cyclase activity did not differ markedly from values found in normal liver cells in PM of all the tumors studied and in liver tissue of the tumor-bearing animals. Distinct alterations were not found in content of cGMP in the tumors, except of hepatomas 60 and 22, in which the nucleotide level exceeded 2-fold the normal value. The ratio cAMP/cGMP was decreased in the most malignant tumors. At the same time, the ratio was distinctly elevated in tumors with the middle level of malignancy (hepatomas 60 and 61).
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PMID:[Concentration of cyclic nucleotides, activity of adenylate cyclase, 3',5'-AMP phosphodiesterase and guanylate cyclase in plasma membranes from liver and hepatomas of different degrees of malignancy]. 3 Feb 12

We have investigated the role of the microsomal oxidative desaturase in defining the aberrant phosphoglyceride fatty acid composition of hepatomas. The microsomal delta 9-stearoyl-CoA, delta 6-oleoyl(linolenoyl)-CoA, and delta 5-eicosatrienoyl-CA desaturase activities were studied in control and host liver and in the poorly differentiated Morris 7777 hepatoma. The delta 9-stearoyl-CoA desaturase of the hepatoma was significantly decreased (42%) relative to control liver, yet the hepatoma specific activity was twice that of host liver. Additionally, the specific activity of the delta 9-stearoyl-CoA desaturase of the tumor was found to decrease with increasing tumor weight. Also this desaturase was inactivated by freezing and thawing. The delta 6-oleoyl(linolenoyl)-CoA and delta 5-eicosatrienoyl-CoA desaturases of the hepatoma were 39% and 4% of control, respectively. The electron transport components involved in the desaturase system were reduced, although this did not appear to be rate-limiting. In addition, two competing metabolic reactions which could lower the observed desaturase activities, hydrolysis of the thioester and incorporation of substrate acyl-CoA molecules into glycerides, did not appear to be responsible for the lowered desaturase activities of the tumor. Thus, it appears that reduced levels of the desaturases themselves may be responsible for the observed activities. These results indicate that the capacity of the hepatoma to biosynthesize polyunsaturated fatty acids is greatly reduced and this is consistent with the decreased polyene content observed in many neoplasms.
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PMID:The acyl-CoA desaturases of microsomes from rat liver and the Morris 7777 hepatoma. 3 69

Areas of hyperplastic livers that acquire hyperbasophilic properties at advanced stages of carcinogenesis apparently represent the sites of neoplastic trasnformation, and hyperstaining of cytoplasmic RNA with basic dyes also characterizes the cancer cells. Estimations of the RNA content of cell fractions from normal rat liver and solid Novikoff hepatoma provided no evidence that the intense staining of cancer cells could be explained on the basis of an increase in cytoplasmic RNA content. The possibility that cytoplasmic fractions of Novikoff hepatoma show greater affinity for basic dyes than corresponding normal fractions has been examined by means of a test-tube toluidine blue-binding assay. The results revealed that the dye-binding capacity of total cytoplasmic fractions from tumors is 75% higher than normal after Carnoy fixation which retains mostly ribosomal RNA. Assays on fresh ribosomes indicated that tumor ribosomes bind 71% more toluidine blue per mg of RNA than the ribosomal preparation from normal liver. This study thus demonstrates a greater affinity of tumor RNA for basic dyes, and a comparison of biochemical and cytophotometric analyses suggests that an increase in basophilia by a factor OF ABOUT 2 WOULD BE DUE TO A qualitative alteration in robosomal RNA molecules and/or ribosome structure in cnacer cells.
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PMID:Biochemical estimation of the basic dye-binding capacity of RNA from rat hepatoma. 4 92


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