The metabolism and DNA binding of the cooked-food mutagen, 2-amino-1-methyl-6-phenylimidazo[4,5-b]pyridine (PhIP) in precision-cut rat liver slices

M. Suzanne Connors, Michael A. Malfatti, James S. Felton

Research output: Contribution to journalArticle

6 Citations (Scopus)

Abstract

Precision-cut liver slices prepared from Aroclor 1254 pretreated male rats were used to investigate the metabolism of 2-amino-1-methyl-6-phenylimidazo[4,5-b]pyridine (PhIP). The acetyltransferase and sulfotransferase inhibitors, pentachlorophenol (PCP) and 2,6-dichloro-4-nitrophenol (DCNP), and the cytochrome P450 inhibitor, α-naphthoflavone (ANF), were used to modulate PhIP metabolism and DNA and protein adduct formation. PCP and DCNP had similar effects on the formation of some PhIP metabolites. PCP and DCNP decreased the formation of 4′-(2-amino-1-methylimidazo[4,5-b]pyrid-6-yl)phenyl sulfate (4′-PhIP-sulfate) and 2-(hydroxyamino)-1-methyl-6-phenylimidazo[4,5-b]pyridine (N-hydroxy-PhIP)-glucuronide to 10% and 55% of controls, respectively. 2-Amino-1-methyl-4′-hydroxy-6-phenylimidazo[4,5-b]pyridine (4′-hydroxy-PhIP) was increased by 50% relative to control levels due to PCP and DCNP treatment. PCP and DCNP had different effects on the formation of other PhIP metabolites. Metabolite formation as percent of control for the uncharacterized metabolite, 'Peak A', was 50% and 100% in incubations with PCP and DCNP, respectively. Formation of 4′-hydroxy-PhIP-glucuronide was decreased to 10% of controls with PCP and increased to 147% of controls with DCNP. PCP and DCNP had no effect on the formation of an unidentified metabolite, 'Peak B'. ANF decreased metabolite formation by 60-95%. None of the enzyme inhibitors had a statistically significant effect on PhIP-DNA binding. Covalent binding of PhIP to protein was slightly decreased in incubations containing DCNP or PCP. The lack of significant changes in covalent binding to either DNA or protein suggests that additional pathways may be important in PhIP bioactivation in rat liver slices. With ANF, there was a significant decrease (35%) in protein binding. These observations on the effects of PCP, DCNP and ANF on PhIP metabolism as well as on covalent binding of PhIP to tissue macromolecules are in close agreement with what was reported earlier in hepatocytes. This indicates that tissue slices from various target tissues for tumorigenesis will be a useful in vitro tool for future studies on heterocyclic amine metabolism. This study provides another important example of the utility of precision-cut tissue slices to investigate xenobiotic metabolism and toxicity.

Original languageEnglish (US)
Pages (from-to)185-202
Number of pages18
JournalChemico-Biological Interactions
Volume96
Issue number2
DOIs
StatePublished - May 19 1995
Externally publishedYes

Fingerprint

Pentachlorophenol
Mutagens
Metabolism
Liver
Rats
Food
Metabolites
DNA
Atrial Natriuretic Factor
Tissue
Glucuronides
2-amino-1-methyl-6-phenylimidazo(4,5-b)pyridine
2,6-dichloro-4-nitrophenol
Chlorodiphenyl (54% Chlorine)
Sulfotransferases
Proteins
Acetyltransferases
DNA Adducts
Level control
Enzyme Inhibitors

Keywords

  • Acetyltransferase
  • Cytochrome P450
  • Liver
  • PhIP
  • Slices
  • Sulfotransferase

ASJC Scopus subject areas

  • Toxicology

Cite this

The metabolism and DNA binding of the cooked-food mutagen, 2-amino-1-methyl-6-phenylimidazo[4,5-b]pyridine (PhIP) in precision-cut rat liver slices. / Connors, M. Suzanne; Malfatti, Michael A.; Felton, James S.

In: Chemico-Biological Interactions, Vol. 96, No. 2, 19.05.1995, p. 185-202.

Research output: Contribution to journalArticle

@article{9de3f3294eaa40a49a6454b60250b583,
title = "The metabolism and DNA binding of the cooked-food mutagen, 2-amino-1-methyl-6-phenylimidazo[4,5-b]pyridine (PhIP) in precision-cut rat liver slices",
abstract = "Precision-cut liver slices prepared from Aroclor 1254 pretreated male rats were used to investigate the metabolism of 2-amino-1-methyl-6-phenylimidazo[4,5-b]pyridine (PhIP). The acetyltransferase and sulfotransferase inhibitors, pentachlorophenol (PCP) and 2,6-dichloro-4-nitrophenol (DCNP), and the cytochrome P450 inhibitor, α-naphthoflavone (ANF), were used to modulate PhIP metabolism and DNA and protein adduct formation. PCP and DCNP had similar effects on the formation of some PhIP metabolites. PCP and DCNP decreased the formation of 4′-(2-amino-1-methylimidazo[4,5-b]pyrid-6-yl)phenyl sulfate (4′-PhIP-sulfate) and 2-(hydroxyamino)-1-methyl-6-phenylimidazo[4,5-b]pyridine (N-hydroxy-PhIP)-glucuronide to 10{\%} and 55{\%} of controls, respectively. 2-Amino-1-methyl-4′-hydroxy-6-phenylimidazo[4,5-b]pyridine (4′-hydroxy-PhIP) was increased by 50{\%} relative to control levels due to PCP and DCNP treatment. PCP and DCNP had different effects on the formation of other PhIP metabolites. Metabolite formation as percent of control for the uncharacterized metabolite, 'Peak A', was 50{\%} and 100{\%} in incubations with PCP and DCNP, respectively. Formation of 4′-hydroxy-PhIP-glucuronide was decreased to 10{\%} of controls with PCP and increased to 147{\%} of controls with DCNP. PCP and DCNP had no effect on the formation of an unidentified metabolite, 'Peak B'. ANF decreased metabolite formation by 60-95{\%}. None of the enzyme inhibitors had a statistically significant effect on PhIP-DNA binding. Covalent binding of PhIP to protein was slightly decreased in incubations containing DCNP or PCP. The lack of significant changes in covalent binding to either DNA or protein suggests that additional pathways may be important in PhIP bioactivation in rat liver slices. With ANF, there was a significant decrease (35{\%}) in protein binding. These observations on the effects of PCP, DCNP and ANF on PhIP metabolism as well as on covalent binding of PhIP to tissue macromolecules are in close agreement with what was reported earlier in hepatocytes. This indicates that tissue slices from various target tissues for tumorigenesis will be a useful in vitro tool for future studies on heterocyclic amine metabolism. This study provides another important example of the utility of precision-cut tissue slices to investigate xenobiotic metabolism and toxicity.",
keywords = "Acetyltransferase, Cytochrome P450, Liver, PhIP, Slices, Sulfotransferase",
author = "Connors, {M. Suzanne} and Malfatti, {Michael A.} and Felton, {James S.}",
year = "1995",
month = "5",
day = "19",
doi = "10.1016/0009-2797(94)03595-Y",
language = "English (US)",
volume = "96",
pages = "185--202",
journal = "Chemico-Biological Interactions",
issn = "0009-2797",
publisher = "Elsevier Ireland Ltd",
number = "2",

}

TY - JOUR

T1 - The metabolism and DNA binding of the cooked-food mutagen, 2-amino-1-methyl-6-phenylimidazo[4,5-b]pyridine (PhIP) in precision-cut rat liver slices

AU - Connors, M. Suzanne

AU - Malfatti, Michael A.

AU - Felton, James S.

PY - 1995/5/19

Y1 - 1995/5/19

N2 - Precision-cut liver slices prepared from Aroclor 1254 pretreated male rats were used to investigate the metabolism of 2-amino-1-methyl-6-phenylimidazo[4,5-b]pyridine (PhIP). The acetyltransferase and sulfotransferase inhibitors, pentachlorophenol (PCP) and 2,6-dichloro-4-nitrophenol (DCNP), and the cytochrome P450 inhibitor, α-naphthoflavone (ANF), were used to modulate PhIP metabolism and DNA and protein adduct formation. PCP and DCNP had similar effects on the formation of some PhIP metabolites. PCP and DCNP decreased the formation of 4′-(2-amino-1-methylimidazo[4,5-b]pyrid-6-yl)phenyl sulfate (4′-PhIP-sulfate) and 2-(hydroxyamino)-1-methyl-6-phenylimidazo[4,5-b]pyridine (N-hydroxy-PhIP)-glucuronide to 10% and 55% of controls, respectively. 2-Amino-1-methyl-4′-hydroxy-6-phenylimidazo[4,5-b]pyridine (4′-hydroxy-PhIP) was increased by 50% relative to control levels due to PCP and DCNP treatment. PCP and DCNP had different effects on the formation of other PhIP metabolites. Metabolite formation as percent of control for the uncharacterized metabolite, 'Peak A', was 50% and 100% in incubations with PCP and DCNP, respectively. Formation of 4′-hydroxy-PhIP-glucuronide was decreased to 10% of controls with PCP and increased to 147% of controls with DCNP. PCP and DCNP had no effect on the formation of an unidentified metabolite, 'Peak B'. ANF decreased metabolite formation by 60-95%. None of the enzyme inhibitors had a statistically significant effect on PhIP-DNA binding. Covalent binding of PhIP to protein was slightly decreased in incubations containing DCNP or PCP. The lack of significant changes in covalent binding to either DNA or protein suggests that additional pathways may be important in PhIP bioactivation in rat liver slices. With ANF, there was a significant decrease (35%) in protein binding. These observations on the effects of PCP, DCNP and ANF on PhIP metabolism as well as on covalent binding of PhIP to tissue macromolecules are in close agreement with what was reported earlier in hepatocytes. This indicates that tissue slices from various target tissues for tumorigenesis will be a useful in vitro tool for future studies on heterocyclic amine metabolism. This study provides another important example of the utility of precision-cut tissue slices to investigate xenobiotic metabolism and toxicity.

AB - Precision-cut liver slices prepared from Aroclor 1254 pretreated male rats were used to investigate the metabolism of 2-amino-1-methyl-6-phenylimidazo[4,5-b]pyridine (PhIP). The acetyltransferase and sulfotransferase inhibitors, pentachlorophenol (PCP) and 2,6-dichloro-4-nitrophenol (DCNP), and the cytochrome P450 inhibitor, α-naphthoflavone (ANF), were used to modulate PhIP metabolism and DNA and protein adduct formation. PCP and DCNP had similar effects on the formation of some PhIP metabolites. PCP and DCNP decreased the formation of 4′-(2-amino-1-methylimidazo[4,5-b]pyrid-6-yl)phenyl sulfate (4′-PhIP-sulfate) and 2-(hydroxyamino)-1-methyl-6-phenylimidazo[4,5-b]pyridine (N-hydroxy-PhIP)-glucuronide to 10% and 55% of controls, respectively. 2-Amino-1-methyl-4′-hydroxy-6-phenylimidazo[4,5-b]pyridine (4′-hydroxy-PhIP) was increased by 50% relative to control levels due to PCP and DCNP treatment. PCP and DCNP had different effects on the formation of other PhIP metabolites. Metabolite formation as percent of control for the uncharacterized metabolite, 'Peak A', was 50% and 100% in incubations with PCP and DCNP, respectively. Formation of 4′-hydroxy-PhIP-glucuronide was decreased to 10% of controls with PCP and increased to 147% of controls with DCNP. PCP and DCNP had no effect on the formation of an unidentified metabolite, 'Peak B'. ANF decreased metabolite formation by 60-95%. None of the enzyme inhibitors had a statistically significant effect on PhIP-DNA binding. Covalent binding of PhIP to protein was slightly decreased in incubations containing DCNP or PCP. The lack of significant changes in covalent binding to either DNA or protein suggests that additional pathways may be important in PhIP bioactivation in rat liver slices. With ANF, there was a significant decrease (35%) in protein binding. These observations on the effects of PCP, DCNP and ANF on PhIP metabolism as well as on covalent binding of PhIP to tissue macromolecules are in close agreement with what was reported earlier in hepatocytes. This indicates that tissue slices from various target tissues for tumorigenesis will be a useful in vitro tool for future studies on heterocyclic amine metabolism. This study provides another important example of the utility of precision-cut tissue slices to investigate xenobiotic metabolism and toxicity.

KW - Acetyltransferase

KW - Cytochrome P450

KW - Liver

KW - PhIP

KW - Slices

KW - Sulfotransferase

UR - http://www.scopus.com/inward/record.url?scp=0028903766&partnerID=8YFLogxK

UR - http://www.scopus.com/inward/citedby.url?scp=0028903766&partnerID=8YFLogxK

U2 - 10.1016/0009-2797(94)03595-Y

DO - 10.1016/0009-2797(94)03595-Y

M3 - Article

VL - 96

SP - 185

EP - 202

JO - Chemico-Biological Interactions

JF - Chemico-Biological Interactions

SN - 0009-2797

IS - 2

ER -