Polymorphisms in the CYP19A1 (aromatase) gene and endometrial cancer risk in Chinese women

Sulfathiazole treats type 2 diabetes by restoring metabolism through activating CYP19A1

Globally, diabetes mellitus has been a major epidemic bringing metabolic and endocrine disorders. Currently, 1 in 11 adults suffers from diabetes mellitus, among the patients >90% contract type 2 diabetes mellitus (T2DM). Therefore, it is urgent to develop new drugs that effectively prevent and treat type 2 diabetes through new targets. With high-throughput screening, we found that sulfathiazole decreased the blood glucose and improved glucose metabolism in T2DM mice. Notably, we discovered that sulfathiazole treated T2DM by activating CYP19A1 protein to synthesize estrogen. Collectively, sulfathiazole along with CYP19A1 target bring new promise for the better therapy of T2DM.

The CYP19A1 (TTTA)n Repeat Polymorphism May Affect the Prostate Cancer Risk: Evidence from a Meta-Analysis

Abnormal aromatase (CYP19A1) expression may participate in prostate cancer (PCa) carcinogenesis. However, the results of studies on the CYP19A1 gene polymorphisms and PCa are conflicting. This meta-analysis aimed to systematically evaluate the associations between the CYP19A1 Arg264Cys polymorphism and the (TTTA)n repeat polymorphism and PCa. Electronic databases (PubMed, EmBase, ScienceDirect, and Cochrane Library) were comprehensively searched to identify eligible studies. The strength of the association between the Arg264Cys polymorphism and PCa was assessed by pooled odds ratios (ORs) and 95% confidence intervals (95% CIs) in allelic, dominant, recessive, homozygous, and heterozygous genetic models. To analyze the impact of the (TTTA)n repeat polymorphism, we sequentially took the N-repeat allele (where N equals 7,8,10,11,12, and 13) as the minor allele and the sum of all the other alleles as the major allele. The ORs and 95% CIs were calculated in the allelic model; this analysis was performed individually for each repeat number. Pooled estimates of nine studies addressing the Arg264Cys polymorphism indicated that this polymorphism was not associated with PCa risk in the overall population or in the Caucasian or Asian subgroups. The 8-repeat allele in the (TTTA)n repeat polymorphism increased PCa risk in the overall population (OR = 1.34, 95% CI = 1.14-1.58, p = .001) and in the subgroup with population-based (PB) controls (OR = 1.41, 95% CI = 1.13-1.74, p = .002) as well as in the subgroup using capillary electrophoresis to identify this polymorphism (OR = 1.34, 95% CI = 1.09-1.65, p = .006).The meta-analysis indicated that the CYP19A1 (TTTA)n repeat polymorphism, but not the Arg264Cys polymorphism, may affect PCa risk.

Association between genetic polymorphisms and endometrial cancer risk: a systematic review

Introduction

Endometrial cancer is one of the most commonly diagnosed cancers in women. Although there is a hereditary component to endometrial cancer, most cases are thought to be sporadic and lifestyle related. The aim of this study was to systematically review prospective and retrospective case–control studies, meta-analyses and genome-wide association studies to identify genomic variants that may be associated with endometrial cancer risk.

Methods

We searched MEDLINE, Embase and CINAHL from 2007 to 2019 without restrictions. We followed PRISMA 2009 guidelines. The search yielded 3015 hits in total. Following duplicate exclusion, 2674 abstracts were screened and 453 full-texts evaluated based on our pre-defined screening criteria. 149 articles were eligible for inclusion.

Results

We found that single nucleotide polymorphisms (SNPs) in HNF1B, KLF, EIF2AK, CYP19A1, SOX4 and MYC were strongly associated with incident endometrial cancer. Nineteen variants were reported with genome-wide significance and a further five with suggestive significance. No convincing evidence was found for the widely studied MDM2 variant rs2279744. Publication bias and false discovery rates were noted throughout the literature.

Conclusion

Endometrial cancer risk may be influenced by SNPs in genes involved in cell survival, oestrogen metabolism and transcriptional control. Larger cohorts are needed to identify more variants with genome-wide significance.

Adenomyosis: genetics of estrogen metabolism

Background To analyze the allelic variants of genes of enzymes involved in estrogen metabolism: CYP1A1, CYP1A2, CYP19 and SULT1A1 using polymerase chain reaction-restriction fragment length polymorphism-restriction fragment length polymorphism (PCR-RFLP) analysis of women with histologically confirmed adenomyosis and women without proliferative diseases of pelvic organs was performed. We studied the following polymorphisms: CYP1A1 M1, T264 → C transition in the 3'-noncoding region; CYP1A2*1F, C734 → A transversion in CYP1A2 gene; C → T transition (Arg264Cys) in exon 7 of CYP19; SULT1A1*2, G638 → A transition (Arg213His) in the SULT1A1 gene. Materials and methods The study included 804 patients. Group I (experimental group) consisted of 268 women with adenomyosis. Inclusion criteria were: histological verification of adenomyosis, consent of patients to participate in the study. Group II (control group) - 536 women without proliferative diseases of the uterus. Inclusion criteria were: lack of proliferative processes of the uterus histologically confirmed by ultrasound examination, patient's consent to participate in the study. Results We found the significant association of C allele, T/C and C/C genotypes of the CYP1A1 gene (CYP1A1 M1 polymorphism), A allele, C/A and A/A genotypes of the CYP1A2 gene (CYP1A2*1F polymorphism) and the T allele, C/T and C/C genotypes of the CYP19 (Arg264Cys polymorphism) gene with the risk for adenomyosis. Conclusions Patients with adenomyosis had increased frequency of C allele, T/C and C/C genotypes of the CYP1A1 gene, A allele, C/A and A/A genotypes of the CYP1A2 gene and T allele and C/T and C/C genotypes of the CYP19 gene and, on the contrary, decreased frequency of the mutant allele and heterozygous and mutant homozygous genotype of the CYP1A2 gene compared to women without proliferative diseases of the uterus.

The impact of genetic polymorphism on CYP19A1 in androgen-deprivation therapy among Japanese men

PURPOSE

Inadequate suppression of testosterone during androgen-deprivation therapy impairs its efficacy. This study investigated the significance of genetic polymorphism in CYP19A1, which encodes aromatase that catalyzes androgens into estrogens, among men treated with primary ADT for metastatic prostate cancer.

METHODS

This study included 80 Japanese patients with metastatic prostate cancer whose serum testosterone levels during ADT were available. The association of CYP19A1 gene polymorphism (rs1870050) with clinicopathological parameters including serum testosterone levels during ADT as well as progression-free survival and overall survival was examined.

RESULTS

Serum testosterone levels during ADT of men carrying homozygous wild-type (AA) in the CYP19A1 gene [median (interquartile range); 11.6 (8.3-20.3) ng/dl] were higher than those in men carrying the heterozygous/homozygous variant (AC/CC) [median (interquartile range); 10.0 (6.4-12.8) ng/dl]. When adjusted by Gleason score, initial PSA, M-stage and serum testosterone level during ADT, heterozygous/homozygous variant (AC/CC) in the CYP19A1 gene was associated with a lower risk of progression to castration resistance [hazard ratio (95% confidence interval), 0.53 [0.29-0.92], p = 0.025], but not to any-cause death [hazard ratio (95% confidence interval), 0.74 [0.36-1.49], p = 0.40].

CONCLUSIONS

These findings suggest that genetic variation in CYP19A1 (rs1870050) might affect the prognosis of patients with metastatic prostate cancer when treated with ADT by regulating serum testosterone levels.

Correlations of pri-Let-7 gene polymorphisms with the recurrence and metastasis of primary liver cancer after transcatheter arterial chemoembolization

BACKGROUND AND AIM

Single nucleotide polymorphisms (SNPs) within miRNAs could change their production or affinity with target genes, thus leading to malignant diseases. This study aims to explore correlations of pri-let-7 gene polymorphisms with the recurrence and metastasis of primary liver cancer (PLC) after a transcatheter arterial chemoembolization (TACE) surgical procedure.

MATERIALS AND METHODS

A total of 302 PLC patients treated with hepatoprotective therapies after TACE were selected to and assigned into recurrent and non-recurrent groups. Genotypes of pri-let-7a-1 rs1073997 and pri-let-7a-2 rs629367 were analyzed by Taqman assay. The relationship between PLC with the mutation of each SNP was determined by a multivariate logistic regression analyses. Moreover, the association between survival and pri-let-7 gene polymorphisms was analyzed by the Kaplan-Meier method. The Progress Free Survival (PFS) curve, correlation of pri-let-7a-1 rs629367 with alcohol, HBsAg-positive and TNM III/IV were analyzed by a stratified analysis. Additionally, the risk factors for the recurrence of PLC were analyzed by a multivariate logistic regression analyses.

RESULTS

Results showed that the allelic frequency of the pri-let-7a-2 rs629367 SNP in the recurrent group was higher than that of the non-recurrent group. The distribution of CC genotype was significantly higher than non-CC genotype in the recurrent group. Alcohol consumption, positive expression of hepatitis B surface antigen (HBsAg), AC + CC genotype of rs629367 and TNM III/IV were determined to be the risk factors for the recurrence and metastasis of PLC after TACE. We found a positive correlation between pri-let-7a-2 rs629367 with alcohol consumption, HBsAg-positive and TNM III/IV. The median PFS of HBsAg-positive and TNM III/IV patients with the AC + CC genotype of rs629367 was shorter than those with non-AC + CC genotype.

CONCLUSION

Our findings provide evidence that patients with PLC that carry the AC + CC genotype of pri-let-7a-2 rs629367 after TACE have a worse prognosis than those who carry the AA genotype. We speculate that the pri-let-7 rs629367 SNP could be used as a predictor of recurrence and metastasis after TACE for patients with PLC.

Impact of R264C and R264H polymorphisms in human aromatase function

The cytochrome P450 aromatase is involved in the last step of sex hormones biosynthesis by converting androgens into estrogens. The human enzyme is highly polymorphic and literature data correlate aromatase single nucleotide polymorphisms to the onset of pathologies such as breast cancer and neurodegenerative diseases. The aims of this study were i) to study the influence of the mutations R264C and R264H on the structure-function of the enzyme also upon phosphorylation by selected kinases and ii) to compare the activity of the variants to that of aromatase wild type in two different cell lines. Far-UV circular dichroism spectroscopy, thermal denaturation experiments and CO-binding assay showed that the two polymorphic variants are correctly folded. Steady-state kinetics experiments showed that rArom R264C and R264H exhibit a 1.5 and 3.4 folds lower catalytic efficiency, respectively, when compared to the wild type protein. Since R264 is part of the consensus motif of PKA and PKG1, phosphorylation experiments were performed to study the effect on aromatase function. Phosphorylation by PKA caused a decrease in activity by 36.2%, 49.3% and 27.9% in the wild type, R264C and R264H proteins respectively. Phosphorylation by PKG1 was also found to decrease the activity by 30.3%, 30.5% and 15.4% in the wild type, R264C and R264H proteins respectively. Experiments performed on the three full-length proteins expressed in human MCF-7 breast cancer cells and rat ST14A neuronal cells showed that, depending on the cell line used, the activity of the proteins is different, implicating different cellular mechanisms modulating aromatase activity. This work demonstrate that R264 polymorphism causes an intrinsic alteration of aromatase activity together with a different consensus for phosphorylation by different kinases, indicating that estrogen production can be different when such mutations are present. These findings are significant in understanding the onset and treatment of pathologies in which aromatase has been shown to be involved.

CYP19A1 fine-mapping and Mendelian randomization: estradiol is causal for endometrial cancer

Candidate gene studies have reported CYP19A1 variants to be associated with endometrial cancer and with estradiol (E2) concentrations. We analyzed 2937 single nucleotide polymorphisms (SNPs) in 6608 endometrial cancer cases and 37 925 controls and report the first genome wide-significant association between endometrial cancer and a CYP19A1 SNP (rs727479 in intron 2, P=4.8×10(-11)). SNP rs727479 was also among those most strongly associated with circulating E2 concentrations in 2767 post-menopausal controls (P=7.4×10(-8)). The observed endometrial cancer odds ratio per rs727479 A-allele (1.15, CI=1.11-1.21) is compatible with that predicted by the observed effect on E2 concentrations (1.09, CI=1.03-1.21), consistent with the hypothesis that endometrial cancer risk is driven by E2. From 28 candidate-causal SNPs, 12 co-located with three putative gene-regulatory elements and their risk alleles associated with higher CYP19A1 expression in bioinformatical analyses. For both phenotypes, the associations with rs727479 were stronger among women with a higher BMI (Pinteraction=0.034 and 0.066 respectively), suggesting a biologically plausible gene-environment interaction.

Placental Aromatase Is Deficient in Placental Ischemia and Preeclampsia

Introduction

Preeclampsia is a maternal hypertensive disorder with uncertain etiology and a leading cause of maternal and fetal mortality worldwide, causing nearly 40% of premature births delivered before 35 weeks of gestation. The first stage of preeclampsia is characterized by reduction of utero-placental blood flow which is reflected in high blood pressure and proteinuria during the second half of pregnancy. In human placenta androgens derived from the maternal and fetal adrenal glands are converted into estrogens by the enzymatic action of placental aromatase. This implies that alterations in placental steroidogenesis and, subsequently, in the functionality or bioavailability of placental aromatase may be mechanistically involved in the pathophysiology of PE.

Methods

Serum samples were collected at 32–36 weeks of gestation and placenta biopsies were collected at time of delivery from PE patients (n = 16) and pregnant controls (n = 32). The effect of oxygen tension on placental cells was assessed by incubation JEG–3 cells under 1% and 8% O₂ for different time periods, Timed-mated, pregnant New Zealand white rabbits (n = 6) were used to establish an in vivo model of placental ischemia (achieved by ligature of uteroplacental vessels). Aromatase content and estrogens and androgens concentrations were measured.

Results

The protein and mRNA content of placental aromatase significantly diminished in placentae obtained from preeclamptic patients compared to controls. Similarly, the circulating concentrations of 17-β-estradiol/testosterone and estrone/androstenedione were reduced in preeclamptic patients vs. controls. These data are consistent with a concomitant decrease in aromatase activity. Aromatase content was reduced in response to low oxygen tension in the choriocarcinoma JEG–3 cell line and in rabbit placentae in response to partial ligation of uterine spiral arteries, suggesting that reduced placental aromatase activity in preeclamptic patients may be associated with chronic placental ischemia and hypoxia later in gestation.

Conclusions

Placental aromatase expression and functionality are diminished in pregnancies complicated by preeclampsia in comparison with healthy pregnant controls.

Adiposity and cancer risk: new mechanistic insights from epidemiology

Excess body adiposity, commonly expressed as body mass index (BMI), is a risk factor for many common adult cancers. Over the past decade, epidemiological data have shown that adiposity-cancer risk associations are specific for gender, site, geographical population, histological subtype and molecular phenotype. The biological mechanisms underpinning these associations are incompletely understood but need to take account of the specificities observed in epidemiology to better inform future prevention strategies.

CYP19 genetic polymorphism haplotype AASA is associated with a poor prognosis in premenopausal women with lymph node-negative, hormone receptor-positive breast cancer

Given the critical role of CYP19 in estrogen synthesis, we investigated the influence of CYP19 gene polymorphisms on the clinical outcome of lymph node- (LN-) negative, hormone receptor- (HR-) positive early breast cancers. Genotyping for the CYP19 polymorphisms rs4646 (A/C), rs1065779 (A/C), CYP19 (TTTA)n (short allele/long (S/L) allele using the 7 TTTA repeat polymorphism as the cut-off), and rs1870050 (A/C) was performed on 296 patients with LN-negative, HR-positive breast cancers. All patients received adjuvant hormonal therapy. Associations were examined between these 4 genotypes and 6 common haplotypes of CYP19 and distant disease-free survival (DDFS), disease-free survival (DFS), and overall survival (OS). Patients were divided into the 6 subhaplotypes of CCLA (41.1%), AASA (17.1%), CASA (11.9%), CCLC (8.9%), CCSA (7.5%), AASC (8.9%), and others (4.6%). In premenopausal patients, haplotype AASA was significantly associated with a poor DDFS (adjusted hazard ratio (aHR), 3.3; P = 0.001), DFS (aHR, 2.5; P = 0.0008), and OS (aHR, 2.9; P = 0.0004) after adjusting for age, tumor size, tumor grade, estrogen receptor status, progesterone receptor status, chemotherapy, pathology, adjuvant hormone therapy, menopausal status, and radiotherapy. Furthermore, haplotype AASA remained a negative prognostic factor for premenopausal patients receiving adjuvant chemotherapy in terms of DDFS (aHR, 4.5; P = 0.0005), DFS (HR, 3.2; P = 0.003), and OS (HR, 6.4; P = 0.0009). However, in postmenopausal patients, haplotype AASA was not associated with a poor prognosis, whereas the AASC haplotype was significantly associated with a poor DFS (aHR, 3.1; P = 0.03) and OS (aHR, 4.4; P = 0.01). Our results indicate that, in patients with LN-negative, HR-positive breast cancers, genetic polymorphism haplotype AASA is associated with poor survival of premenopausal women but does not affect survival of postmenopausal women.

Haplotype structures and functional polymorphic variants of the drug target enzyme aromatase (CYP19A1) in South Indian population

CYP19A1 gene product aromatase (CYP19A1) is a 58-kDa protein and belongs to the member of the cytochrome P450 superfamily, which facilitates the bioconversion of estrogens from androgens. Single-nucleotide polymorphisms (SNPs) of CYP19A1 affect the activity of the enzyme and have been implicated in the association of estrogen-dependent disease, prognosis, therapeutic efficacy, and toxicity of third-generation aromatase inhibitors (AIs). Based on ethnicity, the frequency distribution of CYP19A1 alleles will differ, and until now, no data are available for Indians. Using qRT-PCR with TaqMan assays, the frequencies of functionally important polymorphic variants of CYP19A1 gene were determined in 163 healthy subjects of South Indian origin. The observed frequencies of the CYP19A1 minor alleles for the SNPs rs4646 (T), rs10046 (T), rs700519 (T), rs700518 (G), rs727479 (G), rs4775936 (T), rs10459592 (G), rs749292 (A), rs6493497 (T), and rs7176005 (A) are 41.1 (35.8-46.4), 20.0 (15.6-24.3), 33.7 (28.6-38.9), 17.8 (13.6-21.9), 25.8 (21.0-30.5), 19.9 (15.6-24.3), 33.7 (28.6-38.9), 24.9 (20.2-29.5), 35.9 (30.7-41.1), and 35.9 (30.7-41.1), respectively. Strong linkage disequilibrium existed between CYP19A1 SNPs, and sixteen different haplotype structures with a frequency >1% were derived from all the 10 SNPs tested. The most common being the haplotype (H1) GCTATCTGTG with a frequency of about 17.8%. Gender-specific assessment showed significant difference in the allele frequency for rs749292 (p < 0.04), and greater inter-ethnic variation was detected in the distribution of CYP19A1 variants except for rs727479. Our results could provide preliminary insight for further pharmacogenetic investigations of AIs as well as for subsequent molecular epidemiological studies on the contribution of these variants to the occurrence and development of estrogen-dependent disease in South Indians.

Metabolic pathways involved in 2-methoxyestradiol synthesis and their role in preeclampsia

Preeclampsia (PE) remains a major cause of maternal/fetal morbidity-mortality worldwide. The first stage of PE is characterized by placental hypoxia due to a relative reduction in uteroplacental blood flow, resulting from restricted trophoblast invasion. However, hypoxia is also an essential element for the success of invasion. Under hypoxic conditions, 2-methoxyestradiol (2-ME) could induce the differentiation of cytotrophoblast cells into an invasive phenotype in culture. 2-Methoxyestradiol is generated by catechol-O-methyltransferase, an enzyme involved in the metabolic pathway of estrogens. During pregnancy, circulating 2-ME levels increase significantly when compared to the menstrual cycle. Interestingly, plasma levels of 2-ME are lower in women with PE than in controls, and these differences are apparent weeks or even months before the clinical manifestations of the disease. This article reviews the metabolic pathways involved in 2-ME synthesis and discusses the roles of these pathways in normal and abnormal pregnancies, with particular emphasis on PE.

Variation in the CYP19A1 gene and risk of colon and rectal cancer

CYP19A1, or aromatase, influences estrogen-metabolizing enzymes and may influence cancer risk. We examine variation in the CYP19A1 gene and risk of colorectal cancer using data from population-based case-control studies (colon n = 1,574 cases, 1,970 controls; rectal n = 791 cases, 999 controls). Four SNPs were statistically significantly associated with colon cancer and four were associated with rectal cancer. After adjustment for multiple comparisons, the AA genotype of rs12591359 was associated with an increased risk of colon cancer (OR 1.44 95% CI 1.16-1.80) and the AA genotype of rs2470144 was associated with a reduced risk of rectal cancer (OR 0.65 95% CI 0.50-0.84). Variants of CYP19A1 were associated with CIMP+ and CIMP+/KRAS2-mutated tumors. CT/TT genotypes of rs1961177 were significantly associated with an increased likelihood of a MSI+ colon tumor (OR 1.77 95% CI 1.26-2.37). We observed statistically significant interactions between genetic variation in NFκB1 and CYP19A1 for both colon and rectal cancer. Our data suggest the importance of CYP19A1 in the development of colon and rectal cancer and that estrogen may influence risk through an inflammation-related mechanism.

Multi-variant pathway association analysis reveals the importance of genetic determinants of estrogen metabolism in breast and endometrial cancer susceptibility

Despite the central role of estrogen exposure in breast and endometrial cancer development and numerous studies of genes in the estrogen metabolic pathway, polymorphisms within the pathway have not been consistently associated with these cancers. We posit that this is due to the complexity of multiple weak genetic effects within the metabolic pathway that can only be effectively detected through multi-variant analysis. We conducted a comprehensive association analysis of the estrogen metabolic pathway by interrogating 239 tagSNPs within 35 genes of the pathway in three tumor samples. The discovery sample consisted of 1,596 breast cancer cases, 719 endometrial cancer cases, and 1,730 controls from Sweden; and the validation sample included 2,245 breast cancer cases and 1,287 controls from Finland. We performed admixture maximum likelihood (AML)–based global tests to evaluate the cumulative effect from multiple SNPs within the whole metabolic pathway and three sub-pathways for androgen synthesis, androgen-to-estrogen conversion, and estrogen removal. In the discovery sample, although no single polymorphism was significant after correction for multiple testing, the pathway-based AML global test suggested association with both breast (p_global = 0.034) and endometrial (p_global = 0.052) cancers. Further testing revealed the association to be focused on polymorphisms within the androgen-to-estrogen conversion sub-pathway, for both breast (p_global = 0.008) and endometrial cancer (p_global = 0.014). The sub-pathway association was validated in the Finnish sample of breast cancer (p_global = 0.015). Further tumor subtype analysis demonstrated that the association of the androgen-to-estrogen conversion sub-pathway was confined to postmenopausal women with sporadic estrogen receptor positive tumors (p_global = 0.0003). Gene-based AML analysis suggested CYP19A1 and UGT2B4 to be the major players within the sub-pathway. Our study indicates that the composite genetic determinants related to the androgen–estrogen conversion are important for the induction of two hormone-associated cancers, particularly for the hormone-driven breast tumour subtypes.

Estrogen exposure is the most important risk factor for breast and endometrial cancers. Genetic variation of the genes involved in estrogen metabolism has, however, not been consistently associated with these two cancers. We posited that the genetic risk associated with the estrogen metabolic genes is likely to be carried by multiple variants and is therefore most effectively detected by multi-variant analysis. We carried out a comprehensive association analysis of the estrogen metabolic pathway by interrogating SNPs within 35 genes of the pathway in three tumor samples from Sweden and Finland. Through pathway-based multi-variant association analysis, we showed that the genetic variation within the estrogen metabolic pathway is associated with risk for breast and endometrial cancers and that the genetic variation within the genes involved in androgen-to-estrogen conversion is particularly important for the development of ER–positive and sporadic breast tumors in postmenopausal women. Our study has demonstrated that the influence of genetic variation on hormone exposure has an impact on breast cancer development, especially on the development of hormone-driven breast tumor subtypes. Our study has also highlighted that future genetic studies of the estrogen metabolic genes should focus on the androgen-to-estrogen conversion process.

Polymorphisms in genes of the steroid hormone biosynthesis and metabolism pathways and endometrial cancer risk

OBJECTIVES

The incidence of endometrial cancer has recently increased substantially and studies have shown that altered levels of exogenous and endogenous hormones are associated with individual variation in endometrial cancer risk. The environmental and reproductive risk factors that influence these hormones are well known, however, genetic variants involved in hormone biosynthesis and estrogen metabolism have not been well established in endometrial cancer.

METHODS

To determine whether polymorphisms in genes of the steroid hormone biosynthesis and metabolism pathways are associated with endometrial cancer risk, 28 polymorphisms in 18 genes were genotyped in 191 endometrial cancer cases and 291 healthy controls.

RESULTS

The GSTM1 deletion and the variant (GG) genotype of the CYP1B1 rs1800440 polymorphism were associated with a decreased risk of developing endometrial cancer. Furthermore, combinations of haplotypes in CYP1A1, CYP1B1 and GSTs were associated with a decreased risk. The analysis of the repeat polymorphisms revealed that women with the long repeat allele length of the ESR1 (GT)n repeat polymorphism were at an increased risk of developing endometrial cancer. Conversely, women with two long repeat length alleles of the (CAG)n repeat polymorphism in the AR correlated with a decrease in endometrial cancer risk compared to women with one or two alleles with the short repeat length.

CONCLUSIONS

The findings are consistent with our hypothesis that variability in genes involved in steroidogenesis and estrogen metabolism may alter the risk of developing endometrial cancer, suggesting that they may be useful as biomarkers for genetic susceptibility to endometrial cancer.

Common genetic variation in the sex hormone metabolic pathway and endometrial cancer risk: pathway-based evaluation of candidate genes

BACKGROUND

Estrogen plays a major role in endometrial carcinogenesis, suggesting that common variants of genes in the sex hormone metabolic pathway may be related to endometrial cancer risk. In support of this view, variants in CYP19A1 [cytochrome P450 (CYP), family 19, subfamily A, polypeptide 1] have been associated with both circulating estrogen levels and endometrial cancer risk. Associations with variants in other genes have been suggested, but findings have been inconsistent.

METHODS

We examined 36 sex hormone-related genes using a tagging approach in a population-based case-control study of 417 endometrial cancer cases and 407 controls conducted in Poland. We evaluated common variation in these genes in relation to endometrial cancer risk using sequential haplotype scan, variable-sized sliding window and adaptive rank-truncated product (ARTP) methods.

RESULTS

In our case-control study, the strongest association with endometrial cancer risk was for AR (androgen receptor; ARTP P = 0.006). Multilocus analyses also identified boundaries for a region of interest in AR and in CYP19A1 around a previously identified susceptibility loci. We did not find evidence for consistent associations between previously reported candidate single-nucleotide polymorphisms in this pathway and endometrial cancer risk.

DISCUSSION

In summary, we identified regions in AR and CYP19A1 that are of interest for further evaluation in relation to endometrial cancer risk in future haplotype and subsequent fine mapping studies in larger study populations.

Two estrogen-related variants in CYP19A1 and endometrial cancer risk: a pooled analysis in the Epidemiology of Endometrial Cancer Consortium

Common variants in CYP19A1 (the A alleles of rs749292 and rs727479) have been associated with a 10% to 20% increase in circulating estrogen levels in postmenopausal women. We hypothesized that the presence of one or both A alleles in these single nucleotide polymorphisms (SNP) is associated with increased endometrial cancer risk. We tested this hypothesis in a large pooled analysis of 4,998 endometrial cancer cases and 8,285 controls from 10 studies in the Epidemiology of Endometrial Cancer Consortium. The majority of women (>66%) were whites, with smaller proportions of other races and ethnic groups (blacks, Asians, and Latinas) also included in this pooled analysis. Unconditional logistic regression was used to model the association between SNPs/haplotypes and endometrial cancer risk. Carrying the A allele of either of these SNPs was associated with an increased risk of endometrial cancer, with pooled odds ratios per allele of 1.14, 95% confidence interval of 1.09-1.21, and P = 7.1 x 10(-7) for rs749292, and odds ratio per allele of 1.08, 95% confidence interval of 1.02-1.14, and P = 0.009 for rs727479. For rs749292, these associations were generally stronger among women age >or=55 years. For both SNPs, risk increased with increasing body mass index, and for rs727479, this pattern seemed stronger among women age >or=55 years (P interaction = 0.007). The combination of A alleles in the two SNPs, either by direct count or by haplotype analysis, did not increase risk above that observed for the individual SNPs. Our study provides evidence that CYP19A1 genetic variation influences susceptibility to endometrial cancer, particularly among older and obese women.

Genetic variation in CYP19A1 and risk of breast cancer and fibrocystic breast conditions among women in Shanghai, China

CYP19A1 encodes for aromatase, which irreversibly converts androgens to estrogens; variation in this gene may affect individual susceptibility to breast cancer and other sex hormone-dependent outcomes. In a case-control study nested within a breast self-examination trial conducted in China, we examined whether CYP19A1 polymorphisms (rs1870049, rs1004982, rs28566535, rs936306, rs11636639, rs767199, rs4775936, rs11575899, rs10046, and rs4646) were associated with risk of breast cancer and fibrocystic breast conditions. Cases were diagnosed with breast cancer (n = 614) or fibrocystic breast conditions (n = 465) during 1989 to 2000. Controls were free of breast disease during the same period (n = 879). Presence of proliferative changes within the extratumoral tissue of women with breast cancer and the lesions of women with fibrocystic conditions only was assessed. None of the polymorphisms were associated with overall risk of breast cancer or fibrocystic breast conditions. Differences in breast cancer risk, however, were observed by proliferation status. The risk of breast cancer with (but not without) proliferative fibrocystic conditions was increased among women homozygous for the minor allele of rs1004982 (C), rs28566535 (C), rs936306 (T), and rs4775936 (C) relative to those homozygous for the major allele [age-adjusted odds ratios (95% confidence intervals), 2.19 (1.24-3.85), 2.20 (1.27-3.82), 1.94 (1.13-3.30), and 1.95 (1.07-3.58), respectively]. Also, haplotypes inferred using all polymorphisms were not associated with overall risk of either outcome, although some block-specific haplotypes were associated with an increased risk of breast cancer with concurrent proliferative fibrocystic conditions. Our findings suggest that CYP19A1 variation may enhance breast cancer development in some women, but further confirmation is warranted.

Maximizing resources to study an uncommon cancer: E2C2--Epidemiology of Endometrial Cancer Consortium

Endometrial cancer affects more than 40,000 women a year in the U.S. While the association of this disease with high body mass index and sex steroid hormones is well known, there are many questions about etiology that have not been resolved. Little is known about the genetic basis for risk associated with hormones or obesity, other common genetic factors associated with risk, or gene-environment interactions. E2C2, the Epidemiology of Endometrial Cancer Consortium, was formed in 2006 to provide a collaborative environment for addressing these questions by pooling data from existing studies. This allows for investigations of uncommon risk factors, risk for rare histologic subtypes, and associations within strata that cannot be achieved in individual studies. This report describes the establishment of the consortium, ongoing projects that demonstrate the advantages of collaborative efforts, and challenges faced. Overall, the consortium promises to provide an important means of furthering our knowledge about this cancer.

Association of two common single-nucleotide polymorphisms in the CYP19A1 locus and ovarian cancer risk

Although the role of estrogen in the etiology of ovarian cancer is uncertain, there is increasing evidence that hormone replacement therapy is a risk factor for ovarian malignancy. The production of estrogen involves the conversion of androgens via P450 aromatase, encoded by the CYP19A1 gene. Genetic variation in two CYP19A1 single-nucleotide polymorphisms (SNPs), rs749292 and rs727479, has been found to produce 10-20% increases in estrogen levels among postmenopausal women. We tested the hypothesis that these SNPs were associated with the risk of ovarian cancer in a population-based case-control study in Hawaii, including 367 histologically confirmed epithelial ovarian cancer cases and 602 age- and ethnicity-matched controls. The A allele of rs749292 was positively associated with ovarian cancer risk in a codominant model for all races combined (AG versus AA genotype: odds ratio (OR), 1.48 and 95% confidence interval (CI, 1.07-2.04); GG versus AA: OR, 1.87 (CI, 1.24-2.82); P(trend)=0.002). Similar significant associations of the rs749292 A allele on the risk of ovarian cancer were found among Caucasian and Japanese women. No relation of the rs727479 SNP to ovarian cancer risk was observed overall, although Caucasian women carrying the variant A allele compared with women with an CC genotype had an OR of 2.91 (CI, 1.15-7.37). These data suggest CYP19A1 variants may influence susceptibility to ovarian cancer.

Genetic polymorphisms and endometrial cancer risk

For most sporadic cancers, genetic susceptibility results from the additive effect of multiple genetic variants, each of which contributes a modest risk individually. The study of genetic single nucleotide polymorphisms (SNPs) may help explain the differences in individual cancer susceptibility and may assist in identifying novel markers of risk that can be utilized to create more effective and tailored cancer prevention strategies. Genetic polymorphisms in functionally critical genes have been suggested as risk factors for the development of a variety of cancers, including endometrial cancer. Candidate SNPs may be involved in DNA damage repair, steroid metabolism, carcinogen metabolism, cell-cycle control, apoptosis and steroid receptor activation pathways. In this review, recent findings of genetic association studies exploring genetic polymorphisms and their association with endometrial cancer are reported. In addition, the challenges of genetic association studies, such as power and bias, and the need for validation of promising findings are explored.

Increased prevalence of EGFR-mutant lung cancer in women and in East Asian populations: analysis of estrogen-related polymorphisms

PURPOSE

Somatic mutations in the epidermal growth factor receptor (EGFR) gene occur in a subset of non-small-cell lung cancer (NSCLC) and are highly predictive of the clinical response to selective EGFR kinase inhibitors. The prevalence of EGFR-mutant NSCLC is appreciably higher in females than in males and in East Asian than in Caucasian populations. We hypothesized that these disparate frequencies may be attributable to underlying genetic modifiers. Given the coincident differences in sex and ethnic origin, we tested allozymatic variants of enzymes involved in estrogen biosynthesis and metabolism, encoded by polymorphic alleles known to differ in frequency between Caucasian and Asian populations, as modifying alleles.

EXPERIMENTAL DESIGN

We genotyped nine polymorphisms in the CYP1A1, CYP17A1, CYP19, HSD17B1, COMT, GSTM1, and GSTT1 genes, in a series of 100 Japanese NSCLCs, selected for equal representation of EGFR wild-type (wt) and EGFR-mutant cases, as well as male and female cases. Associations between polymorphic variants and the EGFR genotype and sex of NSCLC cases were examined using Fisher's exact test of significance.

RESULTS

Only CYP1A1 2C showed a difference in allele frequency that approached statistical significance. Heterozygotes were underrepresented among EGFR-mutant cases compared with EGFR-wt cases (27% versus 47%, P = 0.08), with a concurrent trend toward overrepresentation of CYP1A1 2C(Ile/Ile) homozygotes among EGFR-mutant cases as compared with EGFR-wt cases (69% versus 51%, P = 0.13).

CONCLUSION

Within the power of this study, our findings suggest that the selected polymorphic variants in the estrogen biosynthesis and metabolism pathways are unlikely to be major genetic modifiers of the prevalence of EGFR-mutant NSCLC.

Variants in hormone biosynthesis genes and risk of endometrial cancer

We investigated the risk associated with variants in three genes involved in estrogen biosynthesis, CYP11A1, CYP17A1, and CYP19A1, in the population-based case-control study of Estrogen, Diet, Genetics, and Endometrial Cancer. This study was conducted in New Jersey in 2001-2006 with 417 cases and 402 controls. For CYP11A1, there was no association between the number of [TTTTA]( n ) repeats (D15S520) and risk. For CYP17A1, risk was somewhat lower among women with the C/C genotype at T-34C (rs743572) (adjusted OR = 0.65, 95% CI 0.41-1.02). For CYP19A1, risk was lower among women homozygous for the 3-bp deletion (rs11575899) in exon 4 (adjusted OR = 0.44, 95% CI 0.26-0.76), while the number of [TTTA]( n ) repeats was not significantly related to risk: the adjusted OR for n = 7/7 repeats versus n > 7/>7 repeats was 0.81 (95% CI 0.54-1.23). In stratified analyses, results for CYP19A1 were stronger among women with higher (> or =27.4) body mass index: for the homozygous deletion, OR = 0.30 (95% CI 0.15-0.62); for the n = 7/7 genotype, OR = 0.49 (95% CI 0.26-0.93). The interaction between the n = 7/7 genotype and BMI was statistically significant (p = 0.01). The insertion/deletion variant in CYP19A1 appears to be related to risk of endometrial cancer; risk associated with variants in this gene may vary according to BMI.

Interaction of soy food and tea consumption with CYP19A1 genetic polymorphisms in the development of endometrial cancer

Certain polyphenols inhibit the activity of aromatase, a critical enzyme in estrogen synthesis that is coded by the CYP19A1 gene. Consumption of polyphenol-rich foods and beverages, thus, may interact with CYP19A1 genetic polymorphisms in the development of endometrial cancer. The authors tested this hypothesis in the Shanghai Endometrial Cancer Study (1997-2003), a population-based case-control study of 1,204 endometrial cancer cases and 1,212 controls. Dietary information was obtained by use of a validated food frequency questionnaire. Genotypes of CYP19A1 at rs28566535, rs1065779, rs752760, rs700519, and rs1870050 were available for 1,042 cases and 1,035 controls. Unconditional logistic regression models were used to calculate odds ratios and their 95% confidence intervals after adjustment for potential confounding factors. Higher intake of soy foods and tea consumption were both inversely associated with the risk of endometrial cancer, with odds ratios of 0.8 (95% confidence interval: 0.6, 1.0) for the highest versus the lowest tertiles of intake of soy and 0.8 (95% confidence interval: 06, 0.9) for ever tea consumption. The association of single nucleotide polymorphisms rs1065779, rs752760, and rs1870050 with endometrial cancer was modified by tea consumption (p(interaction) < 0.05) but not by soy isoflavone intake. The authors' findings suggest that tea polyphenols may modify the effect of CYP19A1 genetic polymorphisms on the development of endometrial cancer.