Metabolic effects of heterocyclic amines on insulin‑induced AKT phosphorylation and gluconeogenic gene expression are modified by N -acetyltransferase 2 genetic polymorphism.

OBJECTIVE

Heterocyclic amines (HCAs) are mutagens and carcinogens primarily generated when cooking meat at high temperatures or until well-done, and their major metabolic pathway includes hepatic N -hydroxylation via CYP1A2 followed by O -acetylation via N -acetyltransferase 2 (NAT2). NAT2 expresses a well-defined genetic polymorphism in humans resulting in rapid and slow acetylators. Recent epidemiological studies reported significant associations between dietary HCA exposure and insulin resistance and type II diabetes.

METHODS

We assessed the effect of some of the most common HCAs found in cooked meat, 2-amino-3,4-dimethylimidazo[4,5-f]quinoline, 2-amino-3,8-dimethylimidazo[4,5-f]quinoxaline, and 2-amino-1-methyl-6-phenylimidazo[4,5-b]pyridine, on insulin signaling and gluconeogenic gene expression in cryopreserved human hepatocytes characterized by their NAT2 genotype and phenotype to investigate the role of NAT2 genetic polymorphism in HCA-induced metabolic dysregulation.

RESULTS

HCA treatment significantly reduced insulin-induced protein kinase B phosphorylation and significantly increased expression of genes involved in gluconeogenesis ( G6PC , PCK1 , FOXO1 , and PPARA ) in cryopreserved human hepatocytes from rapid but not from slow acetylators.

CONCLUSION

The findings suggest that NAT2 genetic polymorphism modifies HCA-induced insulin resistance and gluconeogenic gene expression, implying that individuals with rapid acetylator phenotype may be at greater risk of dysregulated glucose homeostasis following exposure to HCAs.