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The Journal of Biological Chemistry May 1977Induction of hepatic 4-methylumbelliferone UDP-glucuronosyltransferase (EC 2.4.1.17) by polycyclic aromatic compounds, such as 3-methylcholanthrene or...
Genetic regulation of UDP-glucuronosyltransferase induction by polycyclic aromatic compounds in mice. Co-segregation with aryl hydrocarbon (benzo(alpha)pyrene) hydroxylase induction.
Induction of hepatic 4-methylumbelliferone UDP-glucuronosyltransferase (EC 2.4.1.17) by polycyclic aromatic compounds, such as 3-methylcholanthrene or beta-naphthoflavone, occurs in C57BL/6N, A/J, PL/J, C3HeB/FeJ, and BALB/cJ but not in DBA/2N, AU/SsJ, AKR/J, or RF/J inbred strains of mice. This pattern of five responsive and five nonresponsive mouse strains parallels that of the Ah locus, which controls the induction of aryl hydrocarbon (benzo[alpha]pyrene) hydroxylase (EC 1.14.14.2). Induction of the transferase is maximal in C57BL/6N mice with 200 mg of 3-methylcholanthrene/kg body weight; no induction occurs in nonresponsive DBA/2N mice even at a dose of 400 mg/kg. The rise of inducible transferase activity lags 1 or more days behind the rise of inducible hydroxylase activity and peaks 5 days after a single dose of 3-methylcholanthrene. In offspring from the appropriate backcrosses and intercross between C57BL/6N and DBA/2N parent strains, the genetic expression of 3-methylcholanthrene-inducible transferase activity is inherited as an additive (co-dominant) trait. This expression differs distinctly from that of the inducible hydroxylase activity, which is inherited almost exclusively as a single autosomal dominant trait in these same animals. The more potent inducer 2,3,7,8-tetrachlorodibenzo-p-dioxin induces the transferase more than 3-fold in C57BL/6N mice and less than 2-fold in DBA/2N mice, whereas the hydroxylase is induced equally (about 8-fold) in both strains. A dose of 3-methylcholanthrene given 3 days after 2,3,7,8-tetrachlorodibenzo-p-dioxin, at a time when hydroxylase induction in both strains is very high, does not enhance the rise in inducible transferase activity seen in C57BL/6N or DBA/2N mice which have received 2,3,7,8-tetrachlorodibenzo-p-dioxin alone. These data indicate that (a) the inducibility of two metabolically coordinated membrane-bound enzyme activities may be regulated by a single genetic locus, and (b) although the hydroxylase can be fully induced in the nonresponsive DBA/2N strain by 2,3,7,8-tetrachlorodibenzo-p-dioxin prior to 3-methylcholanthrene treatment, metabolites of the 3-methylcholanthrene treatment, metabolites of the 3-methylcholanthrene treatment, metabolites of the 3-methylcholanthrene, presumably present in the liver, are incapable of inducing further the transferase activity. The difference in sensitivity between 3-methylcholanthrene and the more potent inducer 2,3,7,8-tetrachlorodibenzo-p-dioxin for both the hydroxylase and the transferase activities suggests the possibility of a common receptor in regulating both enzyme induction processes.
Topics: Age Factors; Animals; Aryl Hydrocarbon Hydroxylases; Benzopyrene Hydroxylase; Chromosome Mapping; Dose-Response Relationship, Drug; Enzyme Induction; Female; Flavonoids; Glucuronosyltransferase; Male; Methylcholanthrene; Mice; Mice, Inbred Strains; Microsomes, Liver; Polychlorinated Dibenzodioxins; Polycyclic Compounds; Species Specificity
PubMed: 67114
DOI: No ID Found -
Journal of Biochemistry Nov 1979Hepatic microsomal cytochrome P-450 and P-448 have been purified from phenobarbital (PB)- and 3-methylcholanthrene (MC)-treated rats, by modifications of Imai and Sato's...
Hepatic microsomal cytochrome P-450 and P-448 have been purified from phenobarbital (PB)- and 3-methylcholanthrene (MC)-treated rats, by modifications of Imai and Sato's procedures )1974). The purified preparations of cytochrome P-450 and P-448 were homogeneous judging from their specific contents (17 and 16 nmol per mg protein, respectively) and the results of SDS-polyacrylamide gel electrophoresis and Ouchterlony immunodiffusion analyses. These two cytochromes are different in their physico-chemical and immunological properties, and their substrate specificities. In reconstituted systems containing the purified cytochrome and NADPH-cytochrome P-450 reductase, ethoxycoumarin deethylation and benzo(a)pyrene hydroxylation catalyzed by cytochrome P-450 and P-448 were completely inhibited by the homologous antibody, while essentially no effect was observed with heterologous conbinations of antigen and antibody. In contrast, the benzphetamine demethylation activities of cytochrome P-450 and P-448 were markedly inhibited by the heterologous antibody as well as by the homologous one. These results suggest that the two cytochromes are immunologically different but have some antigenic determinants in common. Drug metabolizing activities of microsomes from PB- and MC-treated rats were inhibited by the antibodies, essentially as expected from the results with the reconstituted systems. The remaining activities in the presence of excess concentrations of the antibody, however, were higher in MC-microsomes treated with anti P-448 antibody than in PB microsomes treated with anti P-450 antibody. These results suggest that cytochrome P-448 molecules may be so localized in the microsomal membrane that the membrane structure may hinder the access of the antibody to the antigenic determinant.
Topics: Amino Acids; Animals; Antibodies; Cytochrome P-450 Enzyme System; Immunoassay; Immunodiffusion; Kinetics; Male; Methylcholanthrene; Microsomes, Liver; NADPH-Ferrihemoprotein Reductase; Phenobarbital; Rats; Spectrophotometry; Substrate Specificity
PubMed: 118169
DOI: 10.1093/oxfordjournals.jbchem.a132655 -
British Journal of Cancer Jun 1973Tumour induction with diethylnitrosamine (DEN) and methylcholanthrene (MCA) has been studied in 3 strains of guinea-pig. A DEN concentration of 80 μg/ml drinking water...
Tumour induction with diethylnitrosamine (DEN) and methylcholanthrene (MCA) has been studied in 3 strains of guinea-pig. A DEN concentration of 80 μg/ml drinking water daily proved too toxic but reasonable survival was obtained with 20 μg/ml 3 times per week in Hartley guinea-pigs and a local inbred strain. Heston Strain 13 guinea-pigs were particularly susceptible to the toxic effects of the diethylnitrosamine. In all3strains, 100% of the animals which survived the early toxic effects subsequently developed hepatomata, the mean time being 15 months. Methylcholanthrene was less toxic but more erratic as a carcinogen, the incidence of tumours in Hartley guinea-pigs varying from 18 to 100% in different experiments, the mean time of tumour development being 10 months.Three transplantable hepatomata and 3 transplantable sarcomata have been developed. The hepatomata are all predominantly hepatocellular carcinomata and the sarcomata comprise two liposarcomata and a fibrosarcoma. Successful shortterm primary cultures of hepatomata, sarcomata and of normal liver tissues have been accomplished. Established cell lines in tissue culture have been developed from one cholangiocarcinoma from an outbred guinea-pig and one transplanted hepatocellular carcinoma from an inbred guinea-pig.
Topics: Animals; Carcinoma, Hepatocellular; Fibrosarcoma; Guinea Pigs; Liposarcoma; Liver Neoplasms; Methylcholanthrene; Neoplasm Transplantation; Neoplasms, Experimental; Nitrosamines; Sarcoma, Experimental
PubMed: 4352789
DOI: 10.1038/bjc.1973.56 -
British Journal of Cancer Dec 1971The subcellular distribution of either [(14)C] or [(3)H]3'-methylcholanthrene was studied in rat liver following a single intraperitoneal injection of the labelled...
The subcellular distribution of either [(14)C] or [(3)H]3'-methylcholanthrene was studied in rat liver following a single intraperitoneal injection of the labelled hydrocarbon 10 hours previously.Adsorbed or non-covalently bound methylcholanthrene and its metabolic derivatives occurred in all cell fractions studied with the exception of purified cell walls. The highest specific activities (d.p.m./mg. protein) were found in washed mitochondria, microsomes and ribosome-free microsomal membranes.Covalent binding of methylcholanthrene and its metabolic derivatives to different cell fractions of rat liver occurs to a small extent and is considered not to be significant. The highest degree of binding occurs in washed mitochondria, microsomes, ribosome-free microsomal membranes and their constituent core proteins.Cell sap which contains non-covalently bound 3'-methylcholanthrene was fractionated into pH 5 enzyme and pH 5 supernatant fractions. The pH 5 enzyme fraction which possesses a high specific activity (d.p.m./mg. protein) was further fractionated with ammonium sulphate into three fractions. The 0-30% ammonium sulphate fraction had the highest specific activity.
Topics: Adsorption; Ammonium Sulfate; Animals; Carbon Isotopes; Cell Fractionation; Cell Membrane; Cell Nucleus; Endoplasmic Reticulum; Hydrogen-Ion Concentration; Injections, Intraperitoneal; Liver; Male; Membranes; Methylcholanthrene; Microsomes, Liver; Mitochondria, Liver; Protein Binding; RNA; Rats; Ribosomes; Tritium
PubMed: 5144545
DOI: 10.1038/bjc.1971.98 -
Theoretical Biology & Medical Modelling Feb 2006The hypothesis of immunosurveillance suggests that new neoplasms arise very frequently, but most are destroyed almost at their inception by an immune response. Its... (Review)
Review
BACKGROUND
The hypothesis of immunosurveillance suggests that new neoplasms arise very frequently, but most are destroyed almost at their inception by an immune response. Its correctness has been debated for many years. In its support, it has been shown that the incidences of many tumor types, though apparently not all, tend to be increased in immunodeficient animals or humans, but this observation does not end the debate.
ALTERNATIVE MODEL
There is an alternative to the surveillance hypothesis; numerous studies have shown that the effect of an immune reaction on a tumor is biphasic. For each tumor, there is some quantitatively low level of immune reaction that, relative to no reaction, is facilitating, perhaps even necessary for the tumor's growth in vivo. The optimum level of this facilitating reaction may often be less than the level of immunity that the tumor might engender in a normal subject.
CONCLUSION
The failure of a tumor to grow as well in the normal as it does in the immunosuppressed host is probably not caused by a lack of tumor-cell killing in the suppressed host. Instead, the higher level of immune response in a normal animal, even if it does not rise to tumor-inhibitory levels, probably gives less positive support to tumor growth. This seems more than a semantic distinction.
Topics: Animals; Carcinogens; Female; Humans; Immunocompetence; Immunocompromised Host; Mammary Neoplasms, Experimental; Mammary Tumor Virus, Mouse; Methylcholanthrene; Mice; Mice, Nude; Mice, SCID; Models, Immunological; Neoplasm Transplantation; Neoplasms; Neoplasms, Experimental; Retroviridae Infections; Transplantation, Isogeneic; Tumor Virus Infections
PubMed: 16457723
DOI: 10.1186/1742-4682-3-6 -
The Journal of Biological Chemistry Jun 1983The effects of phenobarbital, trans-stilbene oxide, and 3-methylcholanthrene on epoxide hydrolase (EC 3.3.2.3) within centrilobular, midzonal, and periportal hepatocytes...
The effects of phenobarbital, trans-stilbene oxide, and 3-methylcholanthrene on epoxide hydrolase (EC 3.3.2.3) within centrilobular, midzonal, and periportal hepatocytes were investigated employing rabbit anti-serum produced against rat hepatic microsomal epoxide hydrolase in unlabeled antibody peroxidase-anti-peroxidase and indirect fluorescent antibody-staining techniques. In livers of control rats, midzonal and periportal hepatocytes bound the anti-epoxide hydrolase to similar extents while centrilobular hepatocytes bound approximately 25% more antibody. 3-Methylcholanthrene did not cause significant alterations in immunohistochemical staining for epoxide hydrolase within any region of the liver lobule, whereas phenobarbital and trans-stilbene oxide produced significant alterations in both the intensity and pattern of intralobular staining for the enzyme. After 4 days of phenobarbital pretreatment, anti-epoxide hydrolase binding to hepatocytes was slightly, but significantly, elevated, especially within midzonal regions. After 7 days of phenobarbital pretreatment, anti-epoxide hydrolase binding was increased by approximately 65% within midzonal regions and by approximately 41 and 24%, respectively, within centrilobular and periportal regions. In livers of trans-stilbene oxide-pretreated rats, anti-epoxide hydrolase binding was increased by approximately 80% within both the midzonal and periportal regions and by approximately 43% within centrilobular regions. These immunohistochemical findings demonstrate that phenobarbital and trans-stilbene oxide both induce epoxide hydrolase nonuniformly within the liver lobule. However, while phenobarbital induces the enzyme to the greatest extent within midzonal hepatocytes and to the least extent within periportal hepatocytes, trans-stilbene oxide induces epoxide hydrolase equally within midzonal and periportal hepatocytes.
Topics: Animals; Epoxide Hydrolases; Fluorescent Antibody Technique; Histocytochemistry; Male; Methylcholanthrene; Microsomes, Liver; Organ Specificity; Phenobarbital; Rats; Stilbenes
PubMed: 6345529
DOI: No ID Found -
The Biochemical Journal Apr 19711. acetyl-(3)H- and ethyl-(14)C-labelled derivatives of phenacetin and related compounds are described. 2. Radioactive label from the ethyl-(14)C-labelled derivatives of...
1. acetyl-(3)H- and ethyl-(14)C-labelled derivatives of phenacetin and related compounds are described. 2. Radioactive label from the ethyl-(14)C-labelled derivatives of 4-nitrophenetole, 4-phenetidine and phenacetin binds in vitro to various extents to bovine plasma albumin, salmon sperm DNA and yeast RNA; the extent of binding is increased in the presence of a rat liver microsomal hydroxylating system and further increased when the microsomal enymes are induced by prior treatment of rats with 3-methylcholanthrene. 3. The ratios of the bound radioactive labels in vitro from [ethyl-(14)C]phenacetin, N-acetoxy[ethyl-(14)C]phenacetin, [acetyl-(3)H]phenacetin and [diacetyl-(3)H]N-acetoxyphenacetin per g-atom of DNA P, RNA P and per mol of protein in the absence of the microsomal system are approximately 1:60:11:863, 1:68:41:1835 and 1:88:713:2399 respectively. 4. Radioactive label from labelled phenacetin binds in vitro to all tissues examined, including the spleen, intestines, kidney and bladder; about 80% of the radioactivity bound to the liver is concentrated in the RNA and proteins. 5. Comparison of the relative extents of binding of radioactive label derived from equimolar amounts of labelled phenacetin, ethanol or acetate shows that the incorporation of labelled C(2) units into tissues and biological macromolecules in vivo and in vitro may account for only a part of the total bound radioactive label derived from phenacetin and not at all from the incorporation of radioactive acetate into nucleic acids. 6. Some implications of these findings are discussed.
Topics: Animals; Binding Sites; Carbon Isotopes; DNA; In Vitro Techniques; Intestinal Mucosa; Kidney; Liver; Male; Methylcholanthrene; Microsomes, Liver; Nucleic Acids; Phenacetin; Protein Binding; RNA; Rats; Serum Albumin, Bovine; Spleen; Tritium; Urinary Bladder
PubMed: 5118104
DOI: 10.1042/bj1220311 -
Environmental Health Perspectives Dec 1996The hepatic metabolism of benzene is thought to be a prerequisite for its bony marrow toxicity. However, the complete pattern of benzene metabolites formed in the liver... (Comparative Study)
Comparative Study
The hepatic metabolism of benzene is thought to be a prerequisite for its bony marrow toxicity. However, the complete pattern of benzene metabolites formed in the liver and their role in bone marrow toxicity are not fully understood. Therefore, benzene metabolism was studied in isolated rodent hepatocytes. Rat hepatocytes released benzene-1,2-dihydrodiol, hydroquinone (HQ), catechol (CT), phenol (PH), trans-trans-muconic acid, and a number of phase II metabolites such as PH sulfate and PH glucuronide. Pretreatment of animals with 3-methylcholantrene (3-MC) markedly increased PH glucuronide formation while PH sulfate formation was decreased. Likewise, V79 cells transfected with the 3-MC-inducible rat UGT1.6 cDNA showed a considerable rate of PH and HQ glucuronidation. In addition to inducing glucuronidation of phenols, 3-MC treatment (reported to protect rats from the myelotoxicity of benzene) resulted in a decrease of hepatic CYP2E1. In contrast, pretreatment of rats with the CYP2E1-inducer isopropanol strongly enhanced benzene metabolism and the formation of phenolic metabolites. Mouse hepatocytes formed much higher amounts of HQ than rat hepatocytes and considerable amounts of 1,2,4-trihydroxybenzene (THB) sulfate and HQ sulfate. In conclusion, the protective effect of 3-MC in rats is probably due to a shift from the labile PH sulfate to the more stable PH glucuronide, and to a decrease in hepatic CYP2E1. The higher susceptibility of mice toward benzene may be related to the high rate of formation of the myelotoxic metabolite HQ and the semistable phase II metabolites HQ sulfate and THB sulfate.
Topics: Animals; Benzene; Bone Marrow; Cytochrome P-450 CYP2E1; Glucuronates; Liver; Male; Methylcholanthrene; Mice; Rats; Rats, Wistar; Species Specificity; Sulfates
PubMed: 9118891
DOI: 10.1289/ehp.961041183 -
Journal of Biochemistry Aug 1980A method is described for the separation and purification of different forms of cytochrome P-450 from liver microsomes of phenobarbital (PB)- and 3-methylcholanthrene...
Multiple forms of cytochrome P-450 purified from liver microsomes of phenobarbital- and 3-methylcholanthrene-pretreated rabbits. I. Resolution, purificaton, and molecular properties.
A method is described for the separation and purification of different forms of cytochrome P-450 from liver microsomes of phenobarbital (PB)- and 3-methylcholanthrene (MC)-pretreated rabbits. It consists of solubilization of microsomes with cholate, followed by successive chromatography on omega-aminooctyl Sepharose 4B, hydroxylapatite and CM-Sephadex C-50 columns. Separation of different forms of cytochrome P-450 is achieved in the aminooctyl Sepharose and hydroxylapatite chromatograhy steps. This method permits the separation of three forms of cytochrome P-450, i.e. "P-450(1)," "P-450(2)," and "P-488(1)," from PB-induced microsomes; P-450(1), the main cytochrome P-450 component in these microsomes, and P-448(1) can each be obtained in a gel-electrophoretically homogeneous state, whereas P-450(2) can be obtained in a partially purified state. Application of the same method to MC-induced microsomes led to the purification of P-448(1), the main component in these microsomes, to homogeneity and to partial purification of a fourth form, i.e. "P-450(3)." P-448(1) from MC-induced microsomes seems to be identical with P-448(1) from PB-induced microsomes in monomeric molecular weight (54,000), amino acid composition and chromatographic behavior. However, P-448(1) from MC-induced microsomes, but not P-448(1) from PB-induced microsomes, contains 0.18 to 0.88 mol of tightly bound MC per mol of protein. P-450(1) has a molecular weight of 49,000 and its amino acid composition is clearly different from that of P-448(1). Although P-450(2) is similar in molecular weight, they differ from each other in chromatographic behavior. P-450(3) seems to be different from P-450(1) in molecular weight, though they are similar to each other in chromatographic behavior. All the cytochrome P-450 preparations can be freed from the detergents used in the purification procedure by CM-Sephadex C-50 chromatography. Detergent-free P-450(1), P-450(2), and P-448(1) exist in aqueous solution as oligomeric aggregates.
Topics: Amino Acids; Animals; Cytochrome P-450 Enzyme System; Isoenzymes; Male; Methylcholanthrene; Microsomes, Liver; Molecular Weight; Phenobarbital; Rabbits; Spectrometry, Fluorescence; Spectrophotometry, Ultraviolet
PubMed: 7419508
DOI: 10.1093/oxfordjournals.jbchem.a132996 -
British Journal of Experimental... Aug 1973The short-term and long-term effects of the administration of 2 carcinogens, diethylnitrosamine and methylcholanthrene, on immunological responses in guinea-pigs have...
The short-term and long-term effects of the administration of 2 carcinogens, diethylnitrosamine and methylcholanthrene, on immunological responses in guinea-pigs have been investigated. The study was undertaken to examine the possibility that these carcinogens act in part through nonspecific immunosuppression. The results show that in the period immediately after commencement of carcinogen administration, one aspect of the delayed hypersensitivity reaction to tuberculin (induration) was decreased in the carcinogen treated animals as compared with the controls. This could possibly reflect a reaction to the immediate toxic effect of the chemicals. In the main long-term study, however, in which the immunological responses were tested 6-9 months after commencement of carcinogen treatment ( where the administration schedules, especially for diethylnitrosamine, could and did result in subsequent tumour induction), there was no immunodepression as evidenced by the results of delayed hypersensitivity reactions to tuberculin, immediate hypersensitivity reactions to ovalbumin, autoimmune reactions to testis and normal lymphocyte transfer tests. It is considered probable that the tumorigenic effect of these 2 compounds is due to their direct carcinogenic properties and is not aided by any substantial nonspecific immunosuppression.
Topics: Animals; Autoimmune Diseases; Carcinogens; Guinea Pigs; Hypersensitivity, Delayed; Hypersensitivity, Immediate; Immunity; Immunosuppression Therapy; Lymphocytes; Male; Methotrexate; Methylcholanthrene; Nitrosamines; Ovalbumin; Testis; Time Factors; Tuberculin Test
PubMed: 4726097
DOI: No ID Found