Role of cytochrome P450 1A2 and N-acetyltransferase 2 in 2, 6-dimethylaniline induced genotoxicity

Abstract The purpose of the current work was to assess a possible role of cytochrome P450 1A2 (CYP1A2) and N-acetyltransferase 2 (NAT2) in the metabolic activation of 2,6-dimethylaniline (2,6-DMA) and also clarify the function of DNA repair in affecting the ultimate mutagenic potency. Two cell lines, nucleotide excision repair (NER)-deficient 5P3NAT2 and proficient 5P3NAT2R9 both expressing CYP1A2 and NAT2, were treated with 2,6-DMA for 48 h or its metabolites for 1 h. Cell survival determined by trypan blue exclusion and MTT assays, and 8-azaadenine-resistant mutants at the adenine phosphoribosyltransferase (aprt) gene locus were evaluated. 5P3NAT2 and 5P3NAT2R9 cells treated with 2,6-DMA and its metabolites showed a dose-dependent increase in cytotoxicity and mutant fraction; N-OH-2,6-DMA and 2,6-DMAP in serum-free α-minimal essential medium (MEM) are more potent than 2,6-DMA in complete MEM. 5P3NAT2 cells was more sensitive to the cytotoxic and mutagenic action than 5P3NAT2R9 cells. H2DCFH-DA assay showed dose-dependent ROS production under 2,6- DMAP treatment. These findings indicate that the genotoxic effects of 2,6-DMA are mediated by CYP1A2 activation via N-hydroxylation and the subsequent esterification by the phase II conjugation enzyme NAT2, and through the generation of ROS by hydroxylamine and/or aminophenol metabolites. NER status is also an important contributor

Association of serum olanzapine concentration and cytochrome P450 1A2 gene polymorphisms: a meta-analysis / 上海交通大学学报（医学版）

Objective: To investigate association of cytochrome P450 1A2 (CYP1A2) gene polymorphisms and serum olanzapine concentration. Methods:Key words including “cytochrome P450 CYP1A2”, “genetic polymorphism”, “antipsychotic”, “olanzapine”, “schizophrenia”, and “serum concentration” were used to search in databases, including SinoMed, Wanfang, Weipu, CNKI, PubMed, Embase and Cochrane Library. The search period was limited from the establishment of the database to February 27th, 2018. STATA/SE 12.0 package was applied to conduct statistical analyses. Results: Four studies with a total of 330 schizophrenic patients were included. In the recessive model of CYP1A2 gene -163C>A SNP, patients with A/A genotype had significantly lower olanzapine concentration/dosage ratio (C/D) than patients with C/C or C/A genotype. Conclusion: A/A homozygote of CYP1A2 gene -163C>A SNP is significantly associated with the decreased olanzapine serum concentration.

Clinical Significance of Human Cytochrome P450 1A2 Ontogeny and Its Gene Polymorphism / 中国药学杂志

The change of human cytochrome P450 1A2 ontogeny and the effect of its gene polymorphism on clinical medication were reviewed. The relevant literatures from various databases were searched, collected, analyzed and summarized. CYP1A2 is one of the major subfamilies in human liver enzyme. It is involved in metabolism of about 8%-10% of drugs in clinic, which has important pharmacological and toxicological implications.The expression and activity of CYP1A2 enzymes were different during development, which had a significant effect on clinical medication in human. Studies can see clearance rates and elimination half-lives differences by using caffeine as a probe substrate.Gene polymorphisms cause activity differences of CYP1A2. Gene polymorphisms of CYP1A2*1C and CYP1A2*1F, have been extensively studied show significant effects on clinical medication in adults.There are very few studies on medication between CYP1A2 gene polymorphism and enzyme activity in premature infants, infants and children. The effect of CYP1A2 enzyme activity is unknown between gene polymorphism and ontogeny interaction during human development.It is very necessary to further study the ontogeny changes of CYP1A2 and its gene polymorphism on drug metabolism for improving the safety and efficacy medication in children.

Functional Significance of Cytochrome P450 1A2 Allelic Variants, P450 1A2*8, *15, and *16 (R456H, P42R, and R377Q)

P450 1A2 is responsible for the metabolism of clinically important drugs and the metabolic activation of environmental chemicals. Genetic variations of P450 1A2 can influence its ability to perform these functions, and thus, this study aimed to characterize the functional significance of three P450 1A2 allelic variants containing nonsynonymous single nucleotide polymorphisms (P450 1A2*8, R456H; *15, P42R; *16, R377Q). Variants containing these SNPs were constructed and the recombinant enzymes were expressed and purified in Escherichia coli. Only the P42R variant displayed the typical CO-binding spectrum indicating a P450 holoenzyme with an expression level of approximately 170 nmol per liter culture, but no P450 spectra were observed for the two other variants. Western blot analysis revealed that the level of expression for the P42R variant was lower than that of the wild type, however the expression of variants R456H and R377Q was not detected. Enzyme kinetic analyses indicated that the P42R mutation in P450 1A2 resulted in significant changes in catalytic activities. The P42R variant displayed an increased catalytic turnover numbers (k(cat)) in both of methoxyresorufin O-demethylation and phenacetin O-deethylation. In the case of phenacetin O-deethylation analysis, the overall catalytic efficiency (k(cat)/K(m)) increased up to 2.5 fold with a slight increase of its K(m) value. This study indicated that the substitution P42R in the N-terminal proline-rich region of P450 contributed to the improvement of catalytic activity albeit the reduction of P450 structural stability or the decrease of substrate affinity. Characterization of these polymorphisms should be carefully examined in terms of the metabolism of many clinical drugs and environmental chemicals.

Relationship between Cytochrome P450 1A2 Gene Polymorphism and Susceptibility to Chronic Obstructive Pulmonary Disease / 中国康复理论与实践

@#Objective To investigate the relationship between cytochrome P450 1A2 (CYP1A2) gene polymorphism and susceptibility to chronic obstructive pulmonary disease (COPD). Methods CYP1A2 gene polymorphisms in 100 COPD cases and 100 healthy controls were tested with polymerase chain reaction- restriction fragment length polymorphism (PCR- RELP). Results Genotype frequencies of 4 SNPs in both the COPD and control groups were in accordance with Hardy-Weinberg equilibrium (P>0.05). There was significant difference between the COPD and control groups in genotype and allele frequencies of 1D and 1F (P<0.05), but not of 1C and 1E (P>0.05). Conclusion CYP1A2*1D and CYP1A2*1F polymorphisms may play an important role in the development of COPD.

Correlation between polymorphism of cytochrome P450 1A2 gene and antidepressant clinical efficacy of duloxetine / 中华行为医学与脑科学杂志

Objective To investigate the relationship between C734A and G-2964A polymorphism of cytochrome P450 1A2 gene and clinical efficacy of duloxetine.Methods 223 patients with depression were treated with duloxetine for six weeks.The clinical efficacy was evaluated with the Hamilton rating scale for depression (HAMD) ;single nucleotide polymorphism (SNP) at position C734A and G-2964A of CYP1A2 gene were identified with restriction fragment length polymorphism(RFLPs) ;then one-way ANOVA was adopted to analyze the relationship between SNP and clinical efficacy.Results (1) In 223 patients,the frequency of allele A at locus 734 was 63.64％,while that of allele A at locus-2964 was 26.82％.(2) 220 patient underwent the whole treating course.The conjoint analysis of two locuses indicated that the decreasing ratio of HAMD score of high-activity group,middle-activity group and low-activity after treatment was (56.05± 10.13) ％,(66.36± 8.66) ％ and (73.82± 7.10) ％ respectively,the differences obtained by pairwise comparison of the three groups were of statistical significance(P＜0.01).Conclusion There is close relationship between C734A and G-2964A polymorphism of CYP1A2 gene and clinical efficacy of duloxetine in the treatment for depression.

Relationship between Cytochrome P450 1A2 Gene Polymorphism and Susceptibility to Chronic Obstructive Pulmonary Disease / 中国康复理论与实践

Objective To investigate the relationship between cytochrome P450 1A2 (CYP1A2) gene polymorphism and susceptibility to chronic obstructive pulmonary disease (COPD). Methods CYP1A2 gene polymorphisms in 100 COPD cases and 100 healthy controls were tested with polymerase chain reaction-restriction fragment length polymorphism (PCR-RELP). Results Genotype frequencies of 4 SNPs in both the COPD and control groups were in accordance with Hardy-Weinberg equilibrium (P>0.05). There was significant differ-ence between the COPD and control groups in genotype and allele frequencies of 1D and 1F (P0.05). Con-clusion CYP1A2*1D and CYP1A2*1F polymorphisms may play an important role in the development of COPD.