The Pharmacogenomics Journal (2006) 6, 189–193 & 2006 Nature Publishing Group All rights reserved 1470-269X/06 $30.00 www.nature.com/tpj ORIGINAL ARTICLE Estrogen-metabolizing gene polymorphisms in the assessment of female hormone-dependent cancer risk ON Mikhailova1, LF Gulyaeva1, Allelic variants of cytochrome P450: CYP1A1, CYP1A2, CYP19 (Aromatase) 1 2 and II-phase enzyme Sulfotransferase (SULT1A1) genes are associated with a AV Prudnikov , AV Gerasimov high risk of hormone-dependent cancers. We estimated a frequency of these 2 and SE Krasilnikov allelic variants in the female Caucasian population of the Novosibirsk region of Russia and their association with the elevated risk of ovarian and 1Institute of Molecular Biology and Biophysics, Novosibirsk, Russia and 2Regional Clinical endometrial cancer. A DNA bank of gynecologic oncology patients, patients Oncological Hospital, Novosibirsk, Russia with benign gynecologic diseases and healthy women was created, and the following single nucleotide polymorphisms (SNPs) were examined: CYP1A1 Correspondence: M1 polymorphism, that is, T264-C transition in the 30-noncoding region; Dr ON Mikhailova, Department of Molecular CYP1A2*1F polymorphism, that is, C734-A transversion in CYP1A2 gene; Mechanisms of Carcinogenesis, Institute of - Molecular Biology and Biophysics, Siberian C T transition (Arg264Cys) in exon 7 of CYP19; SULT1A1*2 polymorphism, Branch of the Russian Academy of Medical that is, G638-A transition (Arg213His) in SULT1A1 gene. A positive Sciences, Timakov Str. 2, Novosibirsk, correlation of C allele of CYP1A2*1F and G allele of SULT1A1*2 with 630117, Russia. hormone-dependent cancers in women was found. Thus, these genes are E-mail: [email protected] 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. The Pharmacogenomics Journal (2006) 6, 189–193. doi:10.1038/sj.tpj.6500365; published online 10 January 2006 Keywords: SNP; drug metabolizing enzymes; polymorphism; endometrial cancer; ovarian cancer Introduction Genetic polymorphisms in drug-metabolizing enzymes contribute to suscep- tibility to a number of diseases. Identification of certain allelic variants of drug- metabolizing enzymes as genetic susceptibility markers can provide an important tool in early diagnosis and prevention. Recently, a worldwide increase in the frequency of female hormone-dependent cancers has been observed, primarily due to endometrial, ovarian and breast cancers. Endometrial cancer (EC) is the most common gynecological cancer. Statistics indicate the case rate of EC in Russia in 1970 was 6.4 per 100 000 women. In 2001, this number has increased to 19.49, with an increase of 8–10% annually.1 In the Novosibirsk region of Russia, the annual rate of increase is 9.4%, and for the last 20 years the case rate of EC has doubled, with the rate among women of reproductive age increasing from Received 5 May 2005; revised 21 November 2 2005; accepted 21 November 2005; published 7 to 15 per 100 000 women. Ovarian cancer (OC) is another type of hormone- online 10 January 2006 dependent cancer. In Russia, the case rate of this disease has increased for the last Estrogen-metabolizing gene polymorphisms ON Mikhailova et al 190 20 years. The mortality rate is high; the main reason is an CYP1A2*1F in cancer patients compared to controls advanced stage of the disease at initial diagnosis. (P ¼ 0.0003) and these results were still statistically signifi- Identified risk factors for hormone-dependent cancers cant after Bonferroni correction for multiple testing. We include endocrine disorders, environmental factors and found no statistical differences (P ¼ 0.097) between patients genetic predisposition. The genetic nature of hormone- with benign tumors and the control group. CYP1A2 AA dependent cancer is supported by the fact that in the homozygotes exhibited a reduction of malignant tumor risk Novosibirsk region there is an increase in the number of (P ¼ 0.0003) and these results were also significant after first-degree relatives diagnosed with cancer (e.g., mother Bonferroni correction. CYP1A2 CA heterozygotes and CC with EC, daughter with breast cancer, son with colon homozygotes exhibited an increase of tumor risk (P ¼ 0.0027 cancer) as well as an increase of the number of patients and P ¼ 0.0139, respectively), but these results did not previously living in areas with radiation (Semipalatinsk, remain statistically significant after Bonferroni correction. Northern Kazakhstan, Altai region) in excess of back- Significant differences were found in the genotype and allele ground.2 distribution for SULT1A1 polymorphism between patients The risk of hormone-dependent cancer is directly or with malignant tumors and controls as well as between indirectly related to reproductive hormones, in particular, patients with benign tumors and controls. Comparison of estrogens.3 The main reason for this is thought to be allele frequencies revealed a deficiency of allele A of estrogen stimulation of cell proliferation in the target SULT1A1*2 in patients with benign tumors (P ¼ 0.0014) organs. The whole process of estrogen metabolism is quite and with malignant tumors (P ¼ 0.0192) compared to complex, but it can be divided in three main stages: controls. However, when a Bonferroni correction was synthesis, metabolism and detoxification. The key enzyme applied the differences between patents with malignant in the complex chain of biochemical reactions during tumors and controls were not statistically significant. the synthesis of estrogens from androgens is the cytochrome SULT1A1 AA homozygotes exhibited a reduction of malig- P450, subfamily 19 (CYP19 or aromatase).4 Estrogens nant tumor risk (P ¼ 0.0068) and benign tumor risk are metabolized by several enzymes, including cytochrome (P ¼ 0.000004) while AG heterozygotes exhibited an increase P450 1A1 and 1A2 (CYP1A1 and CYP1A2), through hydro- of benign tumor risk (P ¼ 0.0061). However, after correction xylation resulting in reactive metabolites.5–8 Further degra- for multiple comparisons only results of reduction of benign dation of these metabolites via detoxification pathways, tumor risk for SULT1A1 AA homozygotes remained statisti- involves participation of sulfotransferase 1A1 (SULT1A1).9 cally significant. This enzyme catalyzes the sulfate conjugation of estrogens metabolites, forming hydrophilic sulfates of estrogens which are excreted in the urine. Endocrine system dis- Discussion turbances may occur through changes in the activities of enzymes involved. The CYP1A1, CYP1A2, CYP19 as well as Female hormone-dependent tumors, such as endometrial SULT1A1 phenotypes vary between human individuals, and ovarian carcinomas, are among the most common suggesting the possibility of genetic component in the malignancies afflicting women from both developing and activities of these enzymes. This relationship has been developed countries.3,16 A preponderance of evidence confirmed by several studies.10–15 indicates that these cancers are multifactorial diseases, with The purpose of our study was to estimate a frequency of genetic susceptibility, environment, nutrition and lifestyle allelic variants of CYP19, CYP1A1, CYP1A2 and SULT1A1 risk factors playing important etiologic roles. Currently, a and their association with the elevated risk of hormone- prevailing concept in the mechanisms of female hormone- dependent cancer in the female population of the Novosi- dependent cancer appearance is the impairment of estrogen birsk region of Russia. metabolism in general, and 17-beta estradiol (E2), in par- ticular. This impairment results in the increased concentra- tion of hormones circulating in blood, or a local increase of Results their content in target tissues.17 The genetic nature of such disorders may also contribute to disease development. For For the detection of germline mutations in genes encoding example, genetic variations of estradiol metabolism have four selected estrogen-metabolizing enzymes, the PCR-RFLP been described as significant contributors to disease suscept- method was used. The genotype and allele distributions for ibility, with variations depending on ethnic background. CYP1A1, CYP1A2, CYP19 and SULT1A1 polymorphisms for In the field of obstetrics and gynecology, the genetic both patients and controls are given in Table 1. There was contribution of polymorphic markers to a series of disorders not a significant difference in both genotype and allele has been characterized.18 Identification of at-risk groups distributions for CYP1A1 and CYP19 polymorphisms in for developing hormone-dependent tumors is one of the patients with benign or malignant tumors. In contrast, most promising approaches to ultimately preventing these significant differences in the genotype and allele distribu- diseases. tions for CYP1A2 polymorphism between patients with In the current work, we report the genetic polymorphism malignant tumors and controls were found. Comparison of of selected estrogen-metabolizing enzymes. A significant allele frequencies revealed a deficiency of A allele of difference in genotypes and allele distributions was obtained The Pharmacogenomics Journal Estrogen-metabolizing gene polymorphisms ON Mikhailova et al 191 Table 1 Genotype and alleles frequencies of CYP1A1, CYP1A2, CYP19 and SULT1A1 polymorphisms Malignant tumor cases Benign tumor cases Controls