skip to main content
OSTI.GOV title logo U.S. Department of Energy
Office of Scientific and Technical Information

Title: Induction of Cyp1a1 and Cyp1b1 and formation of DNA adducts in C57BL/6, Balb/c, and F1 mice following in utero exposure to 3-methylcholanthrene

Abstract

Fetal mice are more sensitive to chemical carcinogens than are adults. Previous studies from our laboratory demonstrated differences in the mutational spectrum induced in the Ki-ras gene from lung tumors isolated from [D2 x B6D2F1]F2 mice and Balb/c mice treated in utero with 3-methylcholanthrene (MC). We thus determined if differences in metabolism, adduct formation, or adduct repair influence strain-specific responses to transplacental MC exposure in C57BL/6 (B6), Balb/c (BC), and reciprocal F1 crosses between these two strains of mice. The induction of Cyp1a1 and Cyp1b1 in fetal lung and liver tissue was determined by quantitative fluorescent real-time PCR. MC treatment caused maximal induction of Cyp1a1 and Cyp1b1 RNA 2-8 h after injection in both organs. RNA levels for both genes then declined in both fetal organs, but a small biphasic, secondary increase in Cyp1a1 was observed specifically in the fetal lung 24-48 h after MC exposure in all four strains. Cyp1a1 induction by MC at 4 h was 2-5 times greater in fetal liver (7000- to 16,000-fold) than fetal lung (2000- to 6000-fold). Cyp1b1 induction in both fetal lung and liver was similar and much lower than that observed for Cyp1a1, with induction ratios of 8- to 18-fold in fetalmore » lung and 10- to 20-fold in fetal liver. The overall kinetics and patterns of induction were thus very similar across the four strains of mice. The only significant strain-specific effect appeared to be the relatively poor induction of Cyp1b1 in the parental strain of B6 mice, especially in fetal lung tissue. We also measured the levels of MC adducts and their disappearance from lung tissue by the P{sup 32} post-labeling assay on gestation days 18 and 19 and postnatal days 1, 4, 11, and 18. Few differences were seen between the different strains of mice; the parental strain of B6 mice had nominally higher levels of DNA adducts 2 (gestation day 19) and 4 (postnatal day 1) days after injection, although this was not statistically significant. These results indicate that differences in Phase I metabolism of MC and formation of MC-DNA adducts are unlikely to account for the marked differences observed in the Ki-ras mutational spectrum seen in previous studies. Further, the results suggest that other genetic factors may interact with chemical carcinogens in determining individual susceptibility to these agents during development.« less

Authors:
 [1];  [2];  [1];  [3];  [4];  [4];  [2];  [5]
  1. Department of Cancer Biology, Comprehensive Cancer Center, Wake Forest University School of Medicine, Winston-Salem, NC 27157 (United States)
  2. Environmental Carcinogenesis Division, National Health and Environmental Effects Research Laboratory, U.S. Environmental Protection Agency, Research Triangle Park, NC 27711 (United States)
  3. Department of Public Health Sciences, Comprehensive Cancer Center, Wake Forest University School of Medicine, Winston-Salem, NC 27157 (United States)
  4. Department of Chemistry, Wake Forest University, Winston-Salem, NC 27109 (United States)
  5. Department of Cancer Biology, Comprehensive Cancer Center, Wake Forest University School of Medicine, Winston-Salem, NC 27157 (United States). E-mail: msmiller@wfubmc.edu
Publication Date:
OSTI Identifier:
20783368
Resource Type:
Journal Article
Resource Relation:
Journal Name: Toxicology and Applied Pharmacology; Journal Volume: 209; Journal Issue: 1; Other Information: DOI: 10.1016/j.taap.2005.03.012; PII: S0041-008X(05)00135-3; Copyright (c) 2005 Elsevier Science B.V., Amsterdam, The Netherlands, All rights reserved; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
60 APPLIED LIFE SCIENCES; 3-METHYLCHOLANTHRENE; ADENOMAS; AMINO ACIDS; CARCINOGENESIS; CARCINOGENS; DNA ADDUCTS; HYDROXYLASES; LABELLING; LIVER; LUNGS; METABOLISM; MICE; PHOSPHATES; PHOSPHORUS 32; POLYMERASE CHAIN REACTION; RNA; TRANSCRIPTION

Citation Formats

Xu Mian, Nelson, Garret B., Moore, Joseph E., McCoy, Thomas P., Dai, Jian, Manderville, Richard A., Ross, Jeffrey A., and Miller, Mark Steven. Induction of Cyp1a1 and Cyp1b1 and formation of DNA adducts in C57BL/6, Balb/c, and F1 mice following in utero exposure to 3-methylcholanthrene. United States: N. p., 2005. Web.
Xu Mian, Nelson, Garret B., Moore, Joseph E., McCoy, Thomas P., Dai, Jian, Manderville, Richard A., Ross, Jeffrey A., & Miller, Mark Steven. Induction of Cyp1a1 and Cyp1b1 and formation of DNA adducts in C57BL/6, Balb/c, and F1 mice following in utero exposure to 3-methylcholanthrene. United States.
Xu Mian, Nelson, Garret B., Moore, Joseph E., McCoy, Thomas P., Dai, Jian, Manderville, Richard A., Ross, Jeffrey A., and Miller, Mark Steven. Tue . "Induction of Cyp1a1 and Cyp1b1 and formation of DNA adducts in C57BL/6, Balb/c, and F1 mice following in utero exposure to 3-methylcholanthrene". United States. doi:.
@article{osti_20783368,
title = {Induction of Cyp1a1 and Cyp1b1 and formation of DNA adducts in C57BL/6, Balb/c, and F1 mice following in utero exposure to 3-methylcholanthrene},
author = {Xu Mian and Nelson, Garret B. and Moore, Joseph E. and McCoy, Thomas P. and Dai, Jian and Manderville, Richard A. and Ross, Jeffrey A. and Miller, Mark Steven},
abstractNote = {Fetal mice are more sensitive to chemical carcinogens than are adults. Previous studies from our laboratory demonstrated differences in the mutational spectrum induced in the Ki-ras gene from lung tumors isolated from [D2 x B6D2F1]F2 mice and Balb/c mice treated in utero with 3-methylcholanthrene (MC). We thus determined if differences in metabolism, adduct formation, or adduct repair influence strain-specific responses to transplacental MC exposure in C57BL/6 (B6), Balb/c (BC), and reciprocal F1 crosses between these two strains of mice. The induction of Cyp1a1 and Cyp1b1 in fetal lung and liver tissue was determined by quantitative fluorescent real-time PCR. MC treatment caused maximal induction of Cyp1a1 and Cyp1b1 RNA 2-8 h after injection in both organs. RNA levels for both genes then declined in both fetal organs, but a small biphasic, secondary increase in Cyp1a1 was observed specifically in the fetal lung 24-48 h after MC exposure in all four strains. Cyp1a1 induction by MC at 4 h was 2-5 times greater in fetal liver (7000- to 16,000-fold) than fetal lung (2000- to 6000-fold). Cyp1b1 induction in both fetal lung and liver was similar and much lower than that observed for Cyp1a1, with induction ratios of 8- to 18-fold in fetal lung and 10- to 20-fold in fetal liver. The overall kinetics and patterns of induction were thus very similar across the four strains of mice. The only significant strain-specific effect appeared to be the relatively poor induction of Cyp1b1 in the parental strain of B6 mice, especially in fetal lung tissue. We also measured the levels of MC adducts and their disappearance from lung tissue by the P{sup 32} post-labeling assay on gestation days 18 and 19 and postnatal days 1, 4, 11, and 18. Few differences were seen between the different strains of mice; the parental strain of B6 mice had nominally higher levels of DNA adducts 2 (gestation day 19) and 4 (postnatal day 1) days after injection, although this was not statistically significant. These results indicate that differences in Phase I metabolism of MC and formation of MC-DNA adducts are unlikely to account for the marked differences observed in the Ki-ras mutational spectrum seen in previous studies. Further, the results suggest that other genetic factors may interact with chemical carcinogens in determining individual susceptibility to these agents during development.},
doi = {},
journal = {Toxicology and Applied Pharmacology},
number = 1,
volume = 209,
place = {United States},
year = {Tue Nov 15 00:00:00 EST 2005},
month = {Tue Nov 15 00:00:00 EST 2005}
}
  • The tumorigenicity of 9-3',4',5',6'-tetrachloro-o-carboxy phenyl-6-hydroxy-2,4,5,7-tetraiodo-3-isoxanthone sodium (CAS: 632-68-8) (also called Food Red 105 (FR 105) or Rose Bengal B), which is widely used for food or cosmetic coloring in Japan, was examined in (C57BL/6N X C3H/N)F1 mice. Animals were divided into 6 groups with 50 mice in each group, and they were given solutions of 0, 0.125, and 0.5% FR 105 in the drinking water starting at 6 weeks of age and ending at 101 weeks. The mean relative thyroid weights in both sexes of mice given 0.125 and 0.5% FR 105 were significantly increased compared to those of controls.more » Enlarged thyroid glands were composed exclusively of colloid goiters characterized by distended follicles lined with flattened follicular cells. The male mice given 0.5% FR 105 had follicular adenomas in the thyroid gland at an incidence of 22.9%, which was significantly higher than the incidence in controls (P less than .005). Radioactive 131I uptake in colloid goiters was markedly decreased compared to that in intact thyroid glands. The results indicate that FR 105 can induce colloid goiters and thyroid adenomas in a dose-dependent manner.« less
  • Cytochrome CYP1A (CYP1A) enzymes catalyze bioactivation of 3-methylcholanthrene (MC) to genotoxic metabolites. Here, we tested the hypothesis that CYP1A2 catalyzes formation of MC-DNA adducts that are preferentially formed in the promoter region of CYP1A1, resulting in modulation of CYP1A1 gene expression. MC bound covalently to plasmid DNA (50 {mu}g) containing human CYP1A1 promoter (pGL3-1A1), when incubated with wild-type (WT) liver microsomes (2 mg) and NAPPH 37 {sup o}C for 2 h, giving rise to 9 adducts, as determined by {sup 32}P-postlabeling. Eighty percent of adducts was located in the promoter region. Transient transfection of the adducted plasmids into rat hepatomamore » (H4IIE) cells for 16 h, followed by MC (1 {mu}M) treatment for 24 h inhibited reporter (luciferase) gene expression by 75%, compared to unadducted controls. Our results suggest that CYP1A2 plays a key role in sequence-specific MC-DNA adduct formation in the CYP1A1 promoter region, leading to attenuation of CYP1A1 gene expression.« less
  • Corticosteroid side-chain isomerase of mouse liver catalyzes the reversible interconversion of the ketol and aldol configurations of the corticosteroid side chain. Activity of the enzyme is under genetic control. To see if the differences in activity that were observed in vitro between inbred strains of mice were also expressed in vivo, the metabolism of 11-deoxy-(1,2-/sup 3/H)corticosterone ((1,2-/sup 3/H)DOC) was studied in BALB/c (C) and C57BL/6 (B6) mice. Maximum radioactivity appeared in most organs within 5-10 min after ip injection. Uptake of tracer into liver was greater for C than B6 mice. Tritium levels in blood, kidney, and pancreas were highermore » in C mice; levels in adrenal, abdominal fat, and mesentery were higher in B6 mice. In both strains, the concentrations of tracer in tissues, except in gastrointestinal tract, declined and reached a minimum within 60 min. Most of the radioactivity (84%) from (1,2-/sup 3/H)DOC accumulated in the lumen of the intestinal tract, and few counts were found in the wall. Intestinal concentrations of /sup 3/H at different postinjection intervals were greater for B6 than C mice. In contrast, twice as much radioactivity appeared in the kidneys of C than of B6 mice. The organs of excretion (kidney, liver, gall bladder, and intestine) concentrated steroid from blood. Heart, striated muscle, and spleen excluded steroid. Four acidic metabolites of (1,2-/sup 3/H)DOC were detected in liver, and two were detected in small intestine. Acids formed in liver did not accumulate, and no differences between C and B6 strains were seen. More acid metabolites accumulated in intestines of C mice than in those of B6 mice. The quantitative aspects of steroid acid formation in vivo are consistent with our previous in vitro findings that livers from C mice synthesize more pregnolic acid from DOC than do livers from B6 mice.« less
  • To clarify the pathophysiological mechanism underlying acute renal injury caused by acute exposure to arsenic, we subcutaneously injected both BALB/c and C57BL/6 mice with sodium arsenite (NaAs; 13.5 mg/kg). BALB/c mice exhibited exaggerated elevation of serum blood urea nitrogen (BUN) and creatinine (CRE) levels, compared with C57BL/6 mice. Moreover, half of BALB/c mice died by 24 h, whereas all C57BL/6 mice survived. Histopathological examination on kidney revealed severe hemorrhages, acute tubular necrosis, neutrophil infiltration, cast formation, and disappearance of PAS-positive brush borders in BALB/c mice, later than 10 h. These pathological changes were remarkably attenuated in C57BL/6 mice, accompanied withmore » lower intrarenal arsenic concentrations, compared with BALB/c mice. Among heavy metal inducible proteins including multidrug resistance-associated protein (MRP)-1, multidrug resistance gene (MDR)-1, metallothionein (MT)-1, and arsenite inducible, cysteine- and histidine-rich RNA-associated protein (AIRAP), intrarenal MDR-1, MT-1, and AIRAP gene expression was enhanced to a similar extent in both strains, whereas NaAs challenge augmented intrarenal MRP-1 mRNA and protein expression levels in C57BL/6 but not BALB/c mice. Moreover, the administration of a specific inhibitor of MRP-1, MK-571, significantly exaggerated acute renal injury in C57BL/6 mice. Thus, MRP-1 is crucially involved in arsenic efflux and eventually prevention of acute renal injury upon acute exposure to NaAs.« less