Enzyme polymorphisms influencing the metabolism of heterocyclic aromatic amines

Luisa Airoldi1, Cinzia Magagnotti, Roberta Pastorelli

  • 1Department of Environmental Health Sciences, Istituto di Ricerche Farmacologiche Mario Negri, Via Eritrea 62, Milan 20157, Italy. airoldi@marionegri.it

Insights

Genetic variations in metabolic enzymes influence heterocyclic aromatic amine (HAA) metabolism, a key step in cancer development. However, these genetic polymorphisms show only minor effects on biomarkers, indicating other factors are involved.

Area of Science:

  • Biochemistry
  • Genetics
  • Cancer Research

Background:

  • Heterocyclic aromatic amines (HA) are dietary carcinogens linked to human cancer.
  • DNA adduct formation is a crucial step in HA-induced carcinogenesis.
  • Metabolic activation, detoxification, and DNA repair influence HA binding to DNA.

Purpose of the Study:

  • To review the impact of genetic polymorphisms in metabolic enzymes on HA metabolism.
  • To explore the relationship between genetic variations and cancer susceptibility from dietary HA exposure.

Main Methods:

  • Literature review focusing on polymorphisms of activating/detoxifying enzymes.
  • Analysis of epidemiological evidence linking genetic polymorphisms to cancer risk.
  • Examination of biomarker levels in relation to genetic variations.

Main Results:

  • Polymorphisms in genes for metabolic enzymes affect HA metabolism.
  • Epidemiological studies suggest associations between genetic polymorphisms and cancer susceptibility.
  • Observed effects of genetic polymorphisms on biomarker levels were slight.

Conclusions:

  • Genetic polymorphisms have a limited impact on HA biomarker levels.
  • Unknown factors likely play a significant role in HA-induced carcinogenesis.
  • Further research is needed to identify additional contributing factors.

Related Concept Videos

Pharmacogenetics of Phase I Enzymes: Cytochrome P450 Isozymes01:28

Pharmacogenetics of Phase I Enzymes: Cytochrome P450 Isozymes

Cytochrome P450 (CYP450) enzymes are a superfamily of heme-containing monooxygenases that play a pivotal role in Phase I drug metabolism by catalyzing oxidation and reduction reactions.These enzymes transform lipophilic xenobiotics into more hydrophilic metabolites, facilitating subsequent Phase II conjugation and eventual excretion. The CYP450 family is classified into families (e.g., CYP1–CYP3) and subfamilies (e.g., CYP2A, CYP2C), based on amino acid sequence homology.CYP450 isoenzymes,...
Pharmacogenetics of Drug Metabolism: Overview01:27

Pharmacogenetics of Drug Metabolism: Overview

Genetic polymorphism in drug metabolism is crucial to the inter-individual variability observed in drug responses. Drug metabolism primarily involves the chemical modification of drugs and other xenobiotics to enhance their elimination by increasing their polarity. Two main classes of enzymes mediate this biotransformation process: Phase I enzymes, primarily cytochrome P450s, catalyze oxidation and reduction reactions, while other enzymes, such as esterases, mediate hydrolysis, and Phase II...
Pharmacogenetics of Phase II Enzymes: N-acetyltransferase, Thiopurine S-methyltransferase, UDP-glucuronosyltransferase01:27

Pharmacogenetics of Phase II Enzymes: N-acetyltransferase, Thiopurine S-methyltransferase, UDP-glucuronosyltransferase

Phase II biotransformation reactions are essential for detoxifying and eliminating xenobiotics, including many pharmaceutical compounds. These reactions typically involve conjugation, the covalent attachment of polar endogenous groups such as glucuronic acid, sulfate, methyl, or acetyl moieties to functional groups introduced during Phase I metabolism. The resulting conjugates are more water-soluble, enabling efficient renal or biliary excretion.The major classes of Phase II enzymes include...
Pharmacogenetic Phenotypes: Alterations in Pharmacokinetics, Drug Targets and Biologic Milieu01:29

Pharmacogenetic Phenotypes: Alterations in Pharmacokinetics, Drug Targets and Biologic Milieu

Genetic variations significantly influence drug response through pharmacokinetics, receptor interactions, and biologic milieu modifications. Pharmacokinetic alterations impact drug metabolism and clearance, affecting efficacy and toxicity. Variants in drug-metabolizing enzymes, such as CYP2C9 and CYP2C19, alter drug activation and elimination. For example, CYP2C9 loss-of-function variants require lower warfarin doses to prevent excessive bleeding, while CYP2C19 variants reduce clopidogrel...
Pharmacogenetics of Drug Targets: β₂-Adrenergic Receptors, Apo E, Thymidylate Synthase01:11

Pharmacogenetics of Drug Targets: β₂-Adrenergic Receptors, Apo E, Thymidylate Synthase

Genetic polymorphisms in drug targets have emerged as critical determinants of interindividual variability in drug response and toxicity. Pharmacogenomic investigations increasingly focus on identifying these variations to personalize and optimize therapeutic interventions. A drug target may be a receptor, enzyme, or signaling protein involved in pharmacologic responses or disease-related pathways. While early pharmacogenetic studies focused primarily on drug metabolism, current research...
Basicity of Heterocyclic Aromatic Amines01:25

Basicity of Heterocyclic Aromatic Amines

Heterocyclic amines, where the N atom is a part of an alicyclic system, are similar in basicity to alkylamines. Interestingly, the heterocyclic amine having a nitrogen atom as part of an aromatic ring has much less basicity than its corresponding alicyclic counterpart. For this reason, as presented in Figure 1, piperidine (pKb = 2.8) is significantly more basic than pyridine (pKb = 8.8).