We estimated the frequency of CYP1A1, CYP1A2, CYP1B1, CYP19, and SULT1A1 allelic variants in a female population of the Novosibirsk district and their association with the elevated risk of breast (BC), ovarian (OC), and endometrial (EC) cancers. Significant differences (OR = 2.34, p = 0.0002) in the allele distributions for CYP1A1 M1 polymorphism between patients with BC (n = 118) and controls (n = 180) were found. No significant difference in both genotype and allele distributions for CYP1A1 polymorphisms in patients with OC (n = 96) and EC (n = 154) was observed. Remarkable differences in the allele and genotype distributions for CYP1A2*1F polymorphism in patients with BC or OC were found (OR = 0.26, p = 0.0000005 and OR = 0.34, p = 0.00000002). There were no differences for this polymorphism in women with EC. In patients with BC no significant differences were found in genotype and allele distributions for R264C polymorphism in the CYP19 gene. The frequency of a mutant CYP19 heterozygote genotype C/T was higher in patients with OC and EC compared with healthy women (OR = 3.87, p = 0.001 and OR = 3.73, p = 0.0004, respectively). Comparison of allele frequencies revealed a deficiency of an allele A of SULT1A1*2 in patients with OC (OR = 0.64, p = 0.019) compared with controls. No differences were found in the genotype and allele distributions for SULT1A1 polymorphism between patients with BC and EC and controls. In addition, there were no difference in allele and genotype distributions for CYP1B1 119G-->T polymorphism between BC and control. In conclusion, these results support the hypothesis that susceptibility gene alleles of estrogen-metabolizing enzymes may differentially influence risk for woman hormone-dependent cancers.

Allelic variants of cytochrome P450: CYP1A1, CYP1A2, CYP19 (Aromatase) and II-phase enzyme Sulfotransferase (SULT1A1) genes are associated with a high risk of hormone-dependent cancers. We estimated a frequency of these allelic variants in the female Caucasian population of the Novosibirsk region of Russia and their association with the elevated risk of ovarian and endometrial cancer. A DNA bank of gynecologic oncology patients, patients with benign gynecologic diseases and healthy women was created, and the following single nucleotide polymorphisms (SNPs) were examined: CYP1A1 M1 polymorphism, that is, T264-C transition in the 3 0 -noncoding region; CYP1A2*1F polymorphism, that is, C734-A transversion in CYP1A2 gene; C-T transition (Arg264Cys) in exon 7 of CYP19; SULT1A1*2 polymorphism, that is, G638-A transition (Arg213His) in SULT1A1 gene. A positive correlation of C allele of CYP1A2*1F and G allele of SULT1A1*2 with hormone-dependent cancers in women was found. Thus, these genes are appropriate candidates for studying the contribution of genetic factors to endocrine disorder and environmentally determined diseases susceptibility. In contrast, no association of CYP19 and CYP1A1 polymorphisms with increased cancer risk was revealed.

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The objective of this study was to investigate cytochrome P4501A1 and 1A2 mRNA, protein, and enzyme activity in the liver of male mice differing in the aryl hydrocarbon receptor (AhR) genotype during treatment with the carcinogenic compounds 3-methylcholanthrene (MC) and o-aminoazotoluene (OAT). The basal levels of the CYP1A1 and CYP1A2 enzyme activities were comparable among the mouse strains examined. Significant interstrain variations were observed after treatment by the inducers: EROD and MROD activities were considerably increased in C57BL and A/Sn mice, but not in AKR, SWR, and DBA mice. Western blot analysis did not detect CYP1A1 in the liver of untreated mice. Treatment of mice with MC or OAT caused CYP1A1 accumulation in the liver of C57BL and A/Sn mice, but not in AKR, SWR, and DBA mice. CYP1A2 was detected in all studied mouse strains in both untreated and inducer-treated livers. The results of multiplex RT-PCR showed that the CYP1A1 mRNA in the liver of untreated mice was hardly detectable while constitutive expression of the CYP1A2 gene was rather high. After treatment with MC and OAT the CYP1A1 mRNA level dramatically increased in all strains examined while the increase in the CYP1A2 mRNA level was not striking. This finding did not correlate with the data on the enzyme activity. Our results demonstrated a discrepancy between the transcription of CYP1A1 and CYP1A2 genes and the inducibility of these enzymes in the liver of mice, suggesting a posttranscriptional mechanism of cytochrome P4501A regulation. This comparison between aromatic hydrocarbon-responsive and -nonresponsive strains could contribute to understanding of cytochrome P4501A gene regulation in the liver under the influence of environmental factors.