CYP1A1 and CYP1B1 genetic polymorphisms, smoking and breast cancer risk in a Finnish Caucasian population

Association of CYP gene polymorphisms with breast cancer risk and prognostic factors in the Jordanian population

Background

Single nucleotide polymorphisms (SNPs) in several CYP genes have been associated with altered breast cancer (BC) risk in different populations. Despite this, there is a dearth of information on the roles of these SNPs in Jordanian BC patients. Therefore, this study aims to determine if there is any single nucleotide polymorphism (SNP) within CYP19A1, CYP2C19, CYP2C9, CYP1B1, CYP3A4, and CYP1A2 genes associated with BC in the Jordanian population. In addition, this work investigates the association between selected BC prognostic factors and variants of the aforementioned CYP candidate genes.

Methods

Blood samples were withdrawn from 221 BC patients and 218 healthy volunteers recruited from the Jordanian population. Genomic DNA was withdrawn and, after quantification and quality control, was genotyped using the Sequenom MassARRAY® system (iPLEX GOLD). Statistical analysis was then carried out to assess allelic and genotypic frequencies as well as genetic association between cases and controls.

Results

The CYP19A1 SNP rs7176005 (p < 0.0045) and the CYP1A2 SNP rs762551 (p = 0.004) were significantly associated with BC risk. However, no such association was found for the screened SNPs of the CYP2C9, CYP1B1, CYP2C19 and CYP3A4 genes. Regarding the prognostic factors of BC, several of the screened SNPs were associated with different pathological and clinical features.

Conclusions

Certain CYP genes, particularly CYP19A1 and CYP1A2, were associated with BC risk and development in the Jordanian population.

Cytochrome P-450 1B1 Leu432Val Polymorphism Does Not Show Association With Breast Cancer in Northern Iranian Women With a History of Infertility

The Cytochrome P-4501B1 (CYP1B1) Leu432Val polymorphism has been previously shown to be associated with some types of cancer and affects CYP1B1-mediated metabolism of various infertility drugs. To establish the frequency of CYP1B1 Leu432Val polymorphism among women with a history of infertility drug use, we studied the genotypes of 147 patients with breast cancer with a history of infertility and 150 cancer-free, infertile women (control group) in Northern Iran. A polymerase chain reaction-based restriction fragment length polymorphism assay was used to detect GG (Val/Val), CG (Leu/Val), and CC (Leu/Leu) genotype frequencies, which did not vary significantly between the 2 patient groups (P = .847). We established for the first time that the incidence of CYP1B1 Leu432Val polymorphism is 46.6% among women with infertility history and breast cancer in Northern Iran. Finally, our results do not show any significant association between CYP1B1 Leu432Val polymorphism and breast cancer in infertile women in this region, who have also received infertility treatment.

Active cigarette smoking, variants in carcinogen metabolism genes and breast cancer risk among pre- and postmenopausal women in Ontario, Canada

Cigarette smoking is strongly associated with various diseases including many cancers; however, evidence regarding breast cancer risk remains inconclusive with some studies reporting no association, and others an increased risk with long duration and early initiation of smoking. Genetic variation in carcinogen-metabolizing enzymes may modify these associations. Breast cancer cases were identified from the Ontario Cancer Registry (OCR) during 2003-2004 and population controls through random digit dialing methods. All subjects completed self-administered questionnaires. Subsequently, saliva samples were obtained from cases (N = 1,776) and controls (N = 1,839) for deoxyribonucleic acid (DNA) extraction. Multivariate logistic regression was used to estimate odds ratio (OR) and 95% confidence intervals (CI) for active smoking variables, and interactions were assessed between smoking and 36 carcinogen-metabolizing candidate gene variants. No statistically significant association was found between active smoking and breast cancer risk among all women nor when stratified by menopausal status; however, nonsignificant increased premenopausal breast cancer risk was observed among current smokers and women smoking before first pregnancy. Several statistically significant interactions were observed between smoking and genetic variants (CYP1A2 1548C>T, CYP1A1 3801T>C, CYP1B1 4326G>C, NAT1 c.-85-1014T>A, UGT1A7 W208R 622T>C, SOD2 c.47T>C, GSTT1 deletion). However, in analyses stratified by these genotypes, smoking ORs had wide confidence intervals (and with few exceptions included 1.0) making interpretations difficult. Active smoking was not associated with breast cancer risk, although several significant interactions were observed between smoking, carcinogen-metabolizing genetic variants, and breast cancer risk.

Passive cigarette smoke exposure during various periods of life, genetic variants, and breast cancer risk among never smokers

The association between passive cigarette smoke exposure and breast cancer risk is inconclusive and may be modified by genotype. The authors investigated lifetime passive cigarette smoke exposures, 36 variants in 12 carcinogen-metabolizing genes, and breast cancer risk among Ontario, Canada, women who had never smoked (2003-2004). DNA (saliva) was available for 920 breast cancer cases and 960 controls. Detailed information about passive smoke exposure was collected for multiple age periods (childhood, teenage years, and adulthood) and environments (home, work, and social). Adjusted odds ratios and 95% confidence intervals were estimated by multivariable logistic regression, and statistical interactions were assessed using the likelihood ratio test. Among postmenopausal women, most associations between passive smoke and breast cancer risk were null, whereas among premenopausal women, nonsignificant positive associations were observed. Significant interactions were observed between certain types of passive smoke exposure and genetic variants in CYP2E1, NAT2, and UGT1A7. While these interactions were statistically significant, the magnitudes of the effect estimates were not consistent or easily interpretable, suggesting that they were perhaps due to chance. Although the results of this study were largely null, it is possible that premenopausal women exposed to passive smoke or carrying certain genetic variants may be at higher risk of breast cancer.

Is genetic polymorphism of ER-α, CYP1A1, and CYP1B1 a risk factor for uterine leiomyoma?

INTRODUCTION

Uterine leiomyoma is the most common benign smooth muscle tumor.

OBJECTIVE

This study was carried out to evaluate the association of ER-α, CYP1A1, and CYP1B1 polymorphisms with uterine leiomyoma in Egyptian women.

METHODS

The study population consisted of 160 patients with uterine leiomyoma and 100 healthy women as control. The genetic polymorphisms for ER-α MSP1 exon 1, CYP1B1 Leu432Val, and CYP1A1 Ile462Val were analyzed by polymerase chain reaction restriction fragment length polymorphism (PCR-RFLP) and DNA sequencing methods.

RESULTS

There were no statistically significant differences in the overall associations between the ER-α exon I CT genotypes and uterine leiomyoma (P = 0.47). However, an elevated risk of uterine leiomyoma was observed among women with the CYP1A1 Ile462Val AG genotype (P = 0.07) and CYP1B1 Leu 432Val C/C genotype (P = 0.08).

CONCLUSION

We concluded that the carriage of CYP1A1 Ile462Val AG and CYP1B1 Leu 432Val CC genotypes predict the susceptibility to leiomyoma in Egyptian women and they are likely to contribute in the pathogenesis of leiomyoma.

NAT2 polymorphisms combining with smoking associated with breast cancer susceptibility: a meta-analysis

To derive a more precise estimation of the relationship between the slow or rapid acetylation resulting from N-acetyltransferase 2 (NAT2) polymorphisms and breast cancer risk, a meta-analysis was performed. PubMed, Medline, Embase, and Web of Science were searched. Crude odds ratios (ORs) with 95% confidence intervals (CIs) were used to assess strength of association. The pooled ORs were performed for slow versus rapid acetylation genotypes. A total of 26 studies including 9,215 cases and 10,443 controls were included in the meta-analysis. Overall, no significantly elevated breast cancer risk was associated with NAT2 slow genotypes when all studies were pooled into the meta-analysis (OR = 1.026, 95% CI = 0.968-1.087). In the subgroup analysis by ethnicity, increased risks were not found for either Caucasians (OR = 1.001, 95% CI = 0.938-1.068) or Asians (OR = 1.155, 95% CI = 0.886-1.506). When stratified by study design, statistically significantly elevated risk associated with NAT2 slow genotypes was only found among hospital-based studies (OR = 1.178, 95% CI = 1.037-1.339). In the subgroup analysis by menopausal status, no statistically significantly increased risk was found in either premenopausal (OR = 1.053, 95% CI = 0.886-1.252) or postmenopausal women (OR = 0.965, 95% CI = 0.844-1.104). When stratified by cumulative smoking exposure, in the subgroup of smokers with high pack-years, NAT2 slow genotypes were significantly associated with increased breast cancer risk (OR = 1.400, 95% CI = 1.099-1.784). In conclusion, this meta-analysis suggested that there is overall lack of association between NAT2 genotypes and breast cancer risk, however, NAT2 polymorphisms when combining with heavy smoking history may contribute to breast cancer susceptibility.

Association of CYP1B1 Polymorphisms with Breast Cancer: A Case-Control Study in the Han Population in Ningxia Hui Autonomous Region, P. R. China

Studies investigating possible associations between cytochrome P4501B1 (CYP1B1) polymorphisms and breast cancer risk have been inconsistent. We set out to ascertain whether there might be an association between polymorphisms in exon 2 (codon 119, G→T) and exon 3 (codon 432, G→C) of CYP1B1 and breast cancer in a Chinese Han population in the rural region of Ningxia. Using an allele-specific polymerase chain reaction method and direct DNA sequencing, the presence or absence of the two CYP1B1 polymorphisms was investigated. Genotype and allele frequencies were analyzed in breast cancer cases (n = 152) and healthy age-matched controls (n = 156). The odds ratio (OR) of 119G→T or 432G→C in breast cancer cases and controls was 3.3 (95% CI: 1.28 to 8.28) and 2.8 (95% CI: 1.04 to 7.51), respectively. In addition, the OR for people with both polymorphisms (119T and 432C) was 4.69 (95% CI: 1.97 to 11.19). Our results suggest that certain polymorphisms in the CYP1B1 gene might increase risk for breast cancer among Han Chinese, perhaps because they influence the efficiency of CYP1B1 bio-transformation of oestrogens or pro-carcinogens into DNA-reactive electrophiles that may act as cancer-initiating agents.

No association between CYP1B1 Val432Leu polymorphism and breast cancer risk: a meta-analysis involving 40,303 subjects

Breast cancer is the most common cancer in women. To date, many publications have evaluated the association between Cytochrome P450 1B1 (CYP1B1) Val432Leu polymorphism and breast cancer risk. However, the results remain inconclusive. In order to derive a more precise estimation of the association, a meta-analysis was performed in this study. By searching Medline, Pubmed, and ISI Web of Knowledge databases, 26 studies including 19,028 cases and 21,275 controls were collected for CYP1B1 Val432Leu polymorphism. Crude ORs with 95% CIs were used to assess the strength of association between CYP1B1 Val432Leu polymorphism and breast cancer risk. The pooled ORs were performed for codominant model, dominant model, and recessive model, respectively. Overall, no significant associations between CYP1B1 Val432Leu polymorphism and breast cancer susceptibility were found for Val/Val versus Leu/Leu (OR = 0.98; 95% CI: 0.90-1.06), Val/Leu versus Leu/Leu (OR = 1.01; 95% CI: 0.93-1.09), Val/Val + Val/Leu versus Leu/Leu (OR = 1.00; 95% CI: 0.93-1.08) and Val/Val versus Val/Leu + Leu/Leu (OR = 0.96; 95% CI: 0.91-1.01). In the stratified analysis by ethnicity, menopausal status and sources of controls, significant associations were still not observed in all genetic models. In conclusion, this meta-analysis provides strong evidence that CYP1B1 Val432Leu polymorphism is not associated with breast cancer risk.

Associations of common variants in genes involved in metabolism and response to exogenous chemicals with risk of multiple myeloma

BACKGROUND

We examined risk of multiple myeloma (MM) associated with variants in genes involved in metabolism and response to exogenous chemicals [cytochrome P450 enzymes (CYP1B1, CYP2C9), epoxide hydrolase (EPHX1), paraoxonase 1 (PON1), arylhydrocarbon hydroxylase receptor (AHR), and NAD(P)H:quinone oxidoreductase (NQO1)].

METHODS

This study included 279 MM cases and 782 controls in a pooled analysis of two population-based case-control studies. One common variant from each candidate gene was genotyped using DNA from blood or buccal cells. We estimated risk of MM associated with each genotype, controlling for race, gender, study site, and age, using odds ratios (OR) and 95% confidence intervals (CI).

RESULTS

Evaluations of the CYP1B1 V432L variant (rs1056836) suggested increased risk of MM among persons with the CG and GG genotypes compared to the CC genotype [OR (95% CI)=1.4 (1.0-2.0)]. Similar results were seen in analyses stratified by race and gender. We did not find any associations between MM and the CYP2C9, EPHX1, NQO1, or PON1 genes.

CONCLUSIONS

CYP1B1 activates chemicals such as polycyclic aromatic hydrocarbons and dioxins to create oxidized, reactive intermediates, and higher gene activity has been shown for the G allele. We conducted the largest analysis to date on MM and these genetic variants and our results provide preliminary evidence that variation in CYP1B1 may influence susceptibility to MM.

Polymorphisms in phase I and phase II metabolism genes and risk of chronic benzene poisoning in a Chinese occupational population

It is widely accepted that the cytotoxicity and genotoxicity of benzene results from the action of reactive metabolites. Therefore, genetic variation in metabolic enzyme genes may contribute to susceptibility to chronic benzene poisoning (CBP) in the exposed population. Using a case-control study that included 268 benzene-poisoned patients and 268 workers occupationally exposed to benzene in South China, we aimed to investigate the association between single-nucleotide polymorphisms in genes with phase I and II of metabolism and risk of CBP. The TaqMan technique was used to detect polymorphisms of CYP1A1, CYP1A2, CYP1B1, ADH1B, EPHX1, EPHX2, NQO1, MPO, GSTP1 and UGT1A6 genes. We also explored potential interactions of these polymorphisms with lifestyle factors such as cigarette smoking and alcohol consumption. A weak positive association was found between glutathione S-transferase pi-1 (GSTP1) rs1695 polymorphism and the risk of CBP (P = 0.046), but this association was not statistically significant (P = 0.117) after adjustment for potential confounders. Further analysis showed that the risk of CBP increased in the subjects with EPHX1 GGAC/GAGT diplotype (P = 0.00057) or AGAC/GAGT diplotype (P = 0.00086). In addition, we found that alcohol drinkers with the EPHX1 rs3738047 GA + AA genotypes and non-alcohol drinkers with the GSTP1 rs1695 AA genotype tended to be more susceptible to benzene toxicity. Our results suggest that genetic polymorphisms in EPHX1 may contribute to risk of CBP in a Chinese occupational population.

CYP1A1 and CYP1B1 genetic polymorphisms and uterine leiomyoma risk in Chinese women

PURPOSE

The aim of the study was to evaluate the association of CYP1A1 and CYP1B1 polymorphisms with uterine leiomyoma in Chinese women.

METHODS

We investigated 100 women with clinically diagnosed uterine leiomyoma and 110 healthy normal subjects from Chinese women. The genetic distribution of two CYP1A1 polymorphisms at MspI, Ile462Val and four CYP1B1 polymorphisms at Arg48Gly, Ala119Ser, Leu432Val, Asp449Asp were analyzed by polymerase chain reaction-restriction fragment length polymorphism and DNA sequencing method.

RESULTS

All the SNPs showed polymorphisms in Chinese women. The genotype A/G and the allele G on Ile462Val was significantly different between uterine leiomyoma patients and controls (P < 0.05).

CONCLUSION

These results suggest that the genotype of CYP1A1 Ile462Val was associated with the increased risk of uterine leiomyomas in Chinese women.