Associations between the CYP17, CYPIB1, COMT and SHBG polymorphisms and serum sex hormones in post-menopausal breast cancer survivors

Precision Medicine in Non Communicable Diseases

Non-communicable diseases (NCDs) are the leading cause of death and disease burden globally, cardiovascular diseases (CVDs) account for the major part of death related to NCDs followed by different types of cancer, chronic obstructive pulmonary disease (COPD), and diabetes. As the World Health Organization (WHO) and the United Nations have announced a 25% reduction in mortality of NCDs by 2025, different communities need to adopt preventive strategies for achieving this goal. Personalized medicine approach as a predictive and preventive strategy aims for a better therapeutic goal to the patients to maximize benefits and reduce harms. The clinical benefits of this approach are already realized in cancer targeted therapy, and its impact on other conditions needs more studies in different societies. In this review, we essentially describe the concept of personalized (or precision) medicine in association with NCDs and the future of precision medicine in prediction, prevention, and personalized treatment.

Novel Strategies on Personalized Medicine for Breast Cancer Treatment: An Update

Breast cancer is the most common cancer type among women worldwide. With breast cancer patients and survivors being reported to experience a repertoire of symptoms that are detrimental to their quality of life, the development of breast cancer treatment strategies that are effective with minimal side effects is therefore required. Personalized medicine, the treatment process that is tailored to the individual needs of each patient, is recently gaining increasing attention for its prospect in the development of effective cancer treatment regimens. Indeed, recent studies have identified a number of genes and molecules that may be used as biomarkers for predicting drug response and severity of common cancer-associated symptoms. These would provide useful clues not only for the determination of the optimal drug choice/dosage to be used in personalized treatment, but also for the identification of gene or molecular targets for the development of novel symptom management strategies, which ultimately would lead to the development of more personalized therapies for effective cancer treatment. In this article, recent studies that would provide potential new options for personalized therapies for breast cancer patients and survivors are reviewed. We suggest novel strategies, including the optimization of drug choice/dosage and the identification of genetic changes that are associated with cancer symptom occurrence and severity, which may help in enhancing the effectiveness and acceptability of the currently available cancer therapies.

Effects of diet composition on weight loss, metabolic factors and biomarkers in a 1-year weight loss intervention in obese women examined by baseline insulin resistance status

BACKGROUND

Obesity is a risk factor for postmenopausal breast cancer incidence and premenopausal and postmenopausal breast cancer mortality, which may be explained by several metabolic and hormonal factors (sex hormones, insulin resistance, and inflammation) that are biologically related. Differential effects of dietary composition on weight loss and these metabolic factors may occur in insulin-sensitive vs. insulin-resistant obese women.

OBJECTIVE

To examine the effect of diet composition on weight loss and metabolic, hormonal and inflammatory factors in overweight/obese women stratified by insulin resistance status in a 1-year weight loss intervention.

METHODS AND RESULTS

Nondiabetic women who were overweight/obese (n=245) were randomly assigned to a lower fat (20% energy), higher carbohydrate (65% energy) diet; a lower carbohydrate (45% energy), higher fat (35% energy) diet; or a walnut-rich (18% energy), higher fat (35% energy), lower carbohydrate (45% energy) diet. All groups lost weight at follow-up (P<0.0001), with mean (SEM) percent loss of 9.2(1.1)% in lower fat, 6.5(0.9)% in lower carbohydrate, and 8.2(1.0)% in walnut-rich groups at 12months. The diet×time×insulin resistance status interaction was not statistically significant in the model for overall weight loss, although insulin sensitive women at 12months lost more weight in the lower fat vs. lower carbohydrate group (7.5kg vs. 4.3kg, P=0.06), and in the walnut-rich vs. lower carbohydrate group (8.1kg vs. 4.3kg, P=0.04). Sex hormone binding globulin increased within each group except in the lower carbohydrate group at 12months (P<0.01). C-reactive protein and interleukin-6 decreased at follow-up in all groups (P<0.01).

CONCLUSIONS

Findings provide some support for differential effects of diet composition on weight loss depending on insulin resistance status. Prescribing walnuts is associated with weight loss comparable to a standard lower fat diet in a behavioral weight loss intervention. Weight loss itself may be the most critical factor for reducing the chronic inflammation associated with increased breast cancer risk and progression.

Associations between null mutations in GSTT1 and GSTM1, the GSTP1 Ile(105)Val polymorphism, and mortality in breast cancer survivors

Purpose

Here we assessed associations between null mutations in glutathione-S-transferase (GST)T1 and GSTM1 genes, and the rs1695 polymorphism in GSTP1 (Ile¹⁰⁵Val), and risk of breast cancer-specific (n=45) and all-cause (n=99) mortality in a multiethnic, prospective cohort of 533 women diagnosed with stage I-IIIA breast cancer in 1995–1999, enrolled in the Health, Eating, Activity, and Lifestyle (HEAL) Study.

Methods

We measured the presence of the null mutation in GSTT1 and GSTM1, and the rs1695 polymorphism in GSTP1 by polymerase chain reaction. We assessed associations between breast-cancer specific and all-cause mortality using Cox proportional hazards models.

Results

Participants with ER-negative tumors were more likely to be GSTT1 null (χ²=4.52; P=0.03), and African American women were more likely to be GSTM1 null (χ²=34.36; P<0.0001). Neither GSTM1 nor GSTT1 null mutations were associated with breast cancer-specific or all-cause mortality. In a model adjusted for body mass index, race/ethnicity, tumor stage and treatment received at diagnosis, the variant Val allele of rs1695 was associated with increased risk of all-cause (HR=1.81, 95% CI 1.16-2.82, P=0.008), but not breast cancer-specific mortality. The GSTT1 null mutation was associated with significantly higher levels of C-reactive protein.

Conclusions

GSTM1 and GSTT1 null genotypes had no effect on outcome; however the variant allele of rs1695 appears to confer increased risk for all-cause mortality in breast-cancer survivors.

Given the limited sample size of most studies examining associations between GST polymorphisms with breast cancer survival, and the lack of women undergoing more contemporary treatment protocols (treated prior to 1999), it may be helpful to re-examine this issue among larger samples of women diagnosed after the late 1990s, who all received some form of chemotherapy or radiotherapy.

Variability in estrogen-metabolizing genes and their association with genomic instability in untreated breast cancer patients and healthy women

In the present study, we investigated the relationship between polymorphisms in the estrogen-metabolizing genes CYP17, CYP1B1, CYP1A1, and COMT and genomic instability in the peripheral blood lymphocytes of 62 BC patients and 62 controls considering that increased or prolonged exposure to estrogen can damage the DNA molecule and increase the genomic instability process in breast tissue. Our data demonstrated increased genomic instability in BC patients and that individuals with higher frequencies of MN exhibited higher risk to BC when belonging Val/Met genotype of the COMT gene. We also observed that CYP17 and CYP1A1 polymorphisms can modify the risk to BC depending on the menopause status. We can conclude that the genetic background in estrogen metabolism pathway can modulate chromosome damage in healthy controls and patients and thereby influence the risk to BC. These findings suggest the importance to ally biomarkers of susceptibility and effects to estimate risk groups.

Comprehensive analysis of hormone and genetic variation in 36 genes related to steroid hormone metabolism in pre- and postmenopausal women from the breast and prostate cancer cohort consortium (BPC3)

CONTEXT

Sex steroids play a central role in breast cancer development.

OBJECTIVE

This study aimed to relate polymorphic variants in 36 candidate genes in the sex steroid pathway to serum concentrations of sex steroid hormones and SHBG.

DESIGN

Data on 700 genetic polymorphisms were combined with existing hormone assays and data on breast cancer incidence, within the European Prospective Investigation into Cancer and Nutrition (EPIC) and the Nurses' Health Study (NHS) cohorts; significant findings were reanalyzed in the Multiethnic Cohort (MEC).

SETTING AND PARTICIPANTS

We analyzed data from a pooled sample of 3852 pre- and postmenopausal Caucasian women from EPIC and NHS and 454 postmenopausal women from MEC.

MAIN OUTCOME MEASURES

Outcome measures were SHBG, testosterone, dehydroepiandrosterone (DHEAS), androstenedione, estrone (E1), and estradiol (E2) as well as breast cancer risk.

RESULTS

Globally significant associations were found among pre- and postmenopausal women combined between levels of SHBG and the SHBG gene and between DHEAS and the FSHR and AKR1C3 genes. Among postmenopausal women, serum E1 and E2 were significantly associated with the genes CYP19 and FSHR, and E1 was associated with ESR1. None of the variants related to serum hormone levels showed any significant association with breast cancer risk.

CONCLUSIONS

We confirmed associations between serum levels of SHBG and the SHBG gene and of E1 and E2 and the CYP19 and ESR1 genes. Novel associations were observed between FSHR and DHEAS, E1, and E2 and between AKR1C3 and DHEAS.

The CYP17A1 -34T > C polymorphism and breast cancer risk in BRCA1 and BRCA2 mutation carriers

Exposure to estrogen has a major effect on breast cancer risk. A polymorphism (-34 T > C; rs743572) in the cytochrome P450c17alpha gene (CYP17A1) encoding an enzyme which controls estrogen levels was reportedly associated with breast cancer risk in average risk populations. The effect of this polymorphism on breast or ovarian cancer risk for BRCA1 and BRCA2 mutation carriers has not been thoroughly investigated. With this aim, 2,221 BRCA1 and BRCA2 mutation carriers (1,313 with breast cancer, 279 with ovarian cancer, and 695 asymptomatic carriers), with either BRCA1 (n = 1693) or BRCA2 (n = 528) germline mutations from seven centers were genotyped for the -34 T > C CYP17 polymorphism. Genotyping was accomplished using Taqman allelic discrimination, matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS) or PCR-based restriction-fragment length polymorphism analysis, and limited sequencing. Data were analyzed using Cox proportional hazards models. The hazard ratios (HRs) for breast cancer was 1.02 (95% CI 0.89-1.17, p = 0.74) and 1.10 (95% CI 0.72-1.67, p = 0.66) for BRCA1 and BRCA2 mutation carriers, respectively. The HRs for ovarian cancer were 1.17 (0.94-1.46, p = 0.17) and 0.91 (0.31-2.67, p = 0.86) for BRCA1 and BRCA2 mutation carriers, respectively. Results remained unaltered when the Israeli cohort (primarily Ashkenazim) was evaluated separately. In conclusion, there was no overall evidence for an association of the -34 T > C CYP17 polymorphism with either breast or ovarian cancer risk in BRCA1 or BRCA2 mutation carriers.

Polymorphisms in the promoter region of ESR2 gene and breast cancer susceptibility

Genetic variations like single nucleotide polymorphisms (SNPs) in genes involved in estrogen biosynthesis, metabolism and signal transduction have been suggested to affect breast cancer susceptibility. In this study we tested the hypothesis that polymorphisms in the promoter of ESR2 gene may be associated with increased risk for breast cancer. We analyzed three SNPs in the promoter region of human ESR2 gene by means of allele-specific tetra-primer PCR. A total of 318 sporadic breast cancer cases and 318 age-matched controls were included in the study. With regard to homozygous genotypes, women with sporadic breast cancer more frequently carried the CC genotype of ESR2 promoter SNP rs2987983 (OR 1.99, p=0.005). Calculation of allele positivity demonstrated that presence of T allele of this SNP was more frequent in healthy women. Our data suggest that a SNP in the promoter region of ESR2 gene might be able to affect breast cancer risk. These results further support the emerging hypothesis that ERbeta is an important factor in breast cancer development.

Genetic polymorphisms are associated with serum levels of sex hormone binding globulin in postmenopausal women

Background

Estrogen activity plays a critical role in bone homeostasis. The serum levels of sex hormone binding globulin (SHBG) influence free estrogen levels and activity on target tissues. The objective of this study was to analyze the influence of common polymorphisms of the SHBG gene on serum SHBG, bone mineral density (BMD), and osteoporotic fractures.

Methods

Four biallelic polymorphisms of the SHBG gene were studied by means of Taqman assays in 753 postmenopausal women. BMD was measured by DXA and serum SHBG was measured by ELISA.

Results

Age, body weight, and two polymorphisms of the SHBG gene (rs6257 and rs1799941 [A/G]) were significantly associated with serum SHBG in unadjusted and age- and weight-adjusted models. Alleles at the rs1799941 locus showed the strongest association with serum SHBG (p = 0.0004). The difference in SHBG levels between women with AA and GG genotypes at the rs1799941 locus was 39%. There were no significant differences in BMD across SHBG genotypes. The genotypes showed similar frequency distributions in control women and women with vertebral or hip fractures.

Conclusion

Some common genetic variants of the SHBG gene, and particularly an A/G polymorphism situated in the 5' region, influence serum SHBG levels. However, a significant association with BMD or osteoporotic fractures has not been demonstrated.

Reproductive steroid hormones and recurrence-free survival in women with a history of breast cancer

Epidemiologic studies fairly consistently show in postmenopausal women that reproductive steroid hormones contribute to primary breast cancer risk, and this association is strongly supported by experimental studies using laboratory animals and model systems. Evidence linking sex hormone concentrations with risk for recurrence in women diagnosed with breast cancer is limited; however, beneficial effects of antiestrogenic therapy on recurrence-free survival suggest that these hormones affect progression and risk for recurrence. This study examined whether baseline serum concentrations of estradiol, testosterone, and sex hormone binding globulin were associated with recurrence-free survival in a nested case-control cohort of women from a randomized diet trial (Women's Healthy Eating and Living Study) who were followed for >7 years after diagnosis. In 153 case-control pairs of perimenopausal and postmenopausal women in this analysis, total estradiol [hazard ratio (HR), 1.41 per unit increase in log concentration; 95% confidence interval (95% CI), 1.01-1.97], bioavailable estradiol (HR, 1.26; 95% CI, 1.03-1.53), and free estradiol (HR, 1.31; 95% CI, 1.03-1.65) concentrations were significantly associated with risk for recurrence. Recurred women had an average total estradiol concentration that was double that of nonrecurred women (22.7 versus 10.8 pg/mL; P = 0.05). Testosterone and sex hormone binding globulin concentrations did not differ between cases and controls and were not associated with risk for recurrence. Although genetic and metabolic factors likely modulate the relationship between circulating sex hormones and risk, results from this study provide evidence that higher serum estrogen concentration contributes to risk for recurrence in women diagnosed with early stage breast cancer.