Urinary androgens and breast cancer risk: results from a long-term prospective study based in Guernsey

Post-menopausal breast cancer: from estrogen to androgen receptor

In the United States, breast cancer is the second leading cause of death among women, and even though different therapies can treat primary breast tumors, most breast cancer-related deaths (>95%) occur due to metastasis. A majority (~70%) of breast tumors are found to express estrogen receptor, and a significant portion (~90%) of ER-positive (ER⁺) breast tumors are also androgen receptor-positive (AR⁺). Although ER is known to promote tumorigenesis, the role and underlying mechanism(s) of AR in these closely knit processes remain controversial. Endocrine therapies are the most commonly used treatment for patients with ER⁺ breast tumors; but, ~30%-50% of initially responsive patients develop resistance to these therapies. Whereas 70%–90% of all breast tumors are AR⁺ and AR overexpression is correlated with endocrine resistance, but the precise molecular mechanism(s) for this association is yet to be studied. Multiple mechanisms have been proposed to show AR and ER interactions, which indicate that AR may preferentially regulate expression of a subset of ER-responsive genes and that may be responsible for breast cancer and its progression in affected patients. On the other hand, most of the ER⁺ breast tumors found in post-menopausal women (~80%); and they have very low 17β-estradiol and high androgen levels, but how these hormonal changes make someone more prone to cancer phenotype has long been a disputed issue. In this study, we have discussed multiple molecular mechanisms that we believe are central to the understanding of the overall contributions of AR in breast cancer and its metastasis in post-menopausal women.

Prolactin serum levels correlate with inflammatory status in drug-naïve first-episode schizophrenia

OBJECTIVES

The present study was to examine the relationship between serum levels of prolactin and the inflammatory status in drug-naïve, first-episode schizophrenia patients with normal weight.

METHODS

Patients with normal weight, drug-naïve, first-episode schizophrenia and healthy controls were enrolled in the study. Serum levels of prolactin (PRL) were measured using electrical chemiluminescence immunoassay. Serum levels of interleukin-1β (IL-1β), tumour necrosis factor-α (TNF-α) and interleukin-6 (IL-6) were examined using enzyme-linked immunosorbent assay (ELISA).

RESULTS

Sixty patients with normal weight, drug-naïve, first-episode schizophrenia and 60 healthy controls were enrolled. The schizophrenia group had higher serum levels of PRL, IL-1β, IL-6 and TNF-α compared with the control group. There was a gender difference of hyperprolactinemia in schizophrenia group. There were positive relationships between serum levels of PRL and serum levels of IL-1β, IL-6 and TNF-α within the schizophrenia group. Within the schizophrenia group, TNF-α was the strongest predictor among the three cytokines for serum levels of prolactin after controlling for gender, age, education, smoking status and disease duration.

CONCLUSIONS

Patients with normal weight, drug-naïve, first-episode schizophrenia present elevated serum levels of PRL, which might be related to the up-regulated inflammatory status in this patient population.

Objective habitual physical activity and estradiol levels in obese Latina adolescents

BACKGROUND

Lifetime physical activity (PA) is associated with decreased breast cancer (BC) risk; reports suggest that PA during adolescence contributes strongly to this relationship. PA lowers production of sex hormones, specifically estradiol, or decreases insulin resistance (IR), thereby lowering risk. Overweight Latina adolescents are insulin resistant and exhibit low levels of PA, potentially increasing their future BC risk.

METHODS

37 obese Latina adolescents (15.7 ± 1.1 yrs) provided measures of PA using accelerometry; plasma follicular phase estradiol, sex-hormone binding globulin, total and free testosterone, dehydroepiandrosterone-sulfate (DHEAS); IR using HOMA-IR; and body composition via DEXA. Partial correlations and stepwise linear regressions assessed cross-sectional relationships between sex hormones, IR and PA. Body composition, and age were included a priori as covariates.

RESULTS

Estradiol was negatively associated with accelerometer counts per minute (CPM; r = -0.4; P = .02), percent time spent in moderate PA (%MPA; r = -0.5; P = .006), and percent time in moderate or vigorous PA (%MVPA; r = -0.5; P = .007). DHEAS was positively associated with CPM (r = .4, P = .009), %MPA (r = .3, P = .04), and %MVPA (r = .3, P = .04). Other sex hormones and IR were not associated with PA measures.

CONCLUSION

This study is the first to show that higher habitual PA was inversely associated with estradiol in obese adolescents.

Androgen receptor polyglutamine repeat number: models of selection and disease susceptibility

Variation in polyglutamine repeat number in the androgen receptor (AR CAGn) is negatively correlated with the transcription of androgen-responsive genes and is associated with susceptibility to an extensive list of human disease. Only a small portion of the heritability for many of these diseases is explained by conventional SNP-based genome-wide association studies, and the forces shaping AR CAGn among humans remains largely unexplored. Here, we propose evolutionary models for understanding selection at the AR CAG locus, namely balancing selection, sexual conflict, accumulation-selection, and antagonistic pleiotropy. We evaluate these models by examining AR CAGn-linked susceptibility to eight extensively studied diseases representing the diverse physiological roles of androgens, and consider the costs of these diseases by their frequency and fitness effects. Five diseases could contribute to the distribution of AR CAGn observed among contemporary human populations. With support for disease susceptibilities associated with long and short AR CAGn, balancing selection provides a useful model for studying selection at this locus. Gender-specific differences AR CAGn health effects also support this locus as a candidate for sexual conflict over repeat number. Accompanied by the accumulation of AR CAGn in humans, these models help explain the distribution of repeat number in contemporary human populations.

gamma-Glutamyl transferase and breast cancer risk

Background:

It has been reported that there is an increased risk of cancer in individuals with elevated levels of serum γ-glutamyl transferase (GGT).

Methods:

In the Guernsey Breast Cancer Cohort Study, GGT was measured in sera from 1803 normal women. Among these women, 251 subsequently developed cancer, of whom 96 developed breast cancer.

Results:

After adjustment for age at entry, height, weight, age at menarche and first birth with nulliparity, there was a highly significant relationship between elevated GGT and breast cancer risk. In the highest quartile, the hazard ratio (HR) was 2.17 (95% confidence interval (CI): 1.19, 3.93). When subdivided by menopausal status, there was a reduced non-significant effect in postmenopausal women, whereas for premenopausal women in the highest quartile, HR was 3.81 (95% CI: 1.37, 10.59). Premenopausal women with serum GGT levels above the normal range had a significantly elevated HR of 4.90 (95% CI: 1.86, 12.94).

Conclusions:

These results suggest that premenopausal women with high normal (above median) serum GGT or elevated levels (⩽40 IU l⁻¹) are at increased risk of breast cancer and might benefit from close surveillance, possibly with breast magnetic resonance imaging scans. Serum GGT may mark previous exposure to carcinogens and lead to the identification of DNA adducts involved in mammary carcinogenesis.

Lifetime cumulative number of menstrual cycles and serum sex hormone levels in postmenopausal women

Objective

Lifetime cumulative number of menstrual cycles is related to breast cancer risk. The aim of this study is to investigate the relation between this index and serum sex hormone levels in postmenopausal women.

Methods

Cross-sectional study including 860 naturally postmenopausal Dutch participants of the European Prospective Investigation into Cancer and Nutrition. Lifetime cumulative number of menstrual cycles was computed using questionnaire data on ages at menarche and menopause, number of pregnancies, breastfeeding, oral contraceptive use (OC) and regularity pattern. Measurements of hormones included estrone (E1), estradiol (E2), andostrenedione, testosterone, sex-hormone binding globulin (SHBG) and dehydroepiandrostenedione sulfate (DHEAS). The relation between the lifetime cumulative number of menstrual cycles and hormone levels was assessed using analysis of covariance. Relations between reproductive characteristics and hormone levels were also studied. Adjustments for characteristics at blood collection included age, years since menopause, BMI, hormone replacement therapy use, OC use, smoking habits, alcohol intake and physical activity were done.

Results

Lifetime cumulative number of cycles was related with SHBG; participants in the lowest category had higher SHBG levels. For the separate characteristics, DHEAS and androstenedione increased significantly with increasing age at menarche, while androstenedione and testosterone decreased with increasing age at menopause. For the parity characteristics, SHBG levels increased according to the number of live births.

Conclusions

Lifetime cumulative number menstrual cycles was related only to SHBG. Therefore, free levels of estrogens or androgens may be related to this number of menstrual cycles estimate, reflecting lifetime exposure to ovarian hormones.

Energy balance adiposity and breast cancer - energy restriction strategies for breast cancer prevention

Excess adiposity over the pre- and postmenopausal years is linked to risk of postmenopausal breast cancer. Weight loss could potentially reduce risk amongst those with excess weight via beneficial effects on the hormonal (decreased circulating levels of oestradiol, testosterone, insulin) and secretory profiles of adipocytes (decreased production of leptin, tumour necrosis factor-alpha, interleukin 6 and increased production of adiponectin). Only modest reductions in adipose tissue are achieved and sustained with current weight loss programmes, which makes strategies to mitigate the adverse metabolic effect of adiposity a priority for cancer prevention. The adverse hormonal and secretory effects of adipose tissue are influenced substantially by acute changes in energy balance prior to changes in adiposity. Human and animal studies have shown dietary energy restriction to bring about favourable changes in circulating levels of insulin, leptin, sex hormone binding globulin, insulin-like growth factor-1, oestradiol, testosterone, reactive oxygen species, and the production and secretion of locally acting adipokines and inflammatory cytokines, that is, increased adiponectin and decreased interleukin-6. Achieving and sustaining energy restriction remains a difficult challenge. Intermittent energy restriction is a potential strategy for promoting periods of energy restriction on a long-term basis. Animal and human data suggest that intermittent energy restriction may have cancer preventative effects beyond that of chronic energy restriction and weight loss. Intermittent energy restriction may be a potential strategy for the primary prevention of breast cancer.

HLA system affects the age-at-onset in chronic myeloid leukemia

Chronic myeloid leukemia (CML) occurs from childhood to old age. The adult form is characterized by the presence of Philadelphia chromosome resulting from bcr/abl translocation. The BCR-ABL fusion proteins are immunogenic, and the junctional sequences show unique HLA class I and class II restriction patterns in vitro. A previous study in the west of Scotland showed an influence of several HLA genotypes on the age-at-onset of CML. In the present study, we examined the HLA-A, -B, and -DRB1/3/4/5 allele and haplotype distributions in Turkish CML patients diagnosed in a single center where they are routinely HLA-typed by PCR-SSP analysis as a preparation for stem cell transplantation. The patients were 169 subjects of age 17-60 years. The older patients were not HLA typed and missing from the study group. The age-matched control group (n = 213) was healthy blood donors from the same geographical area. HLA-B*37 showed a risk association with CML [P = 0.02; odds ratio (OR) = 5.35]. The DRB1*10 association at similar magnitude was due to its linkage disequilibrium (LD) with B*37. HLA-B*35 and DRB1*11 showed independent protective effects (P = 0.007 and 0.017; OR = 0.54 and 0.60, respectively). The protective association of DRB1*11 may be due to its involvement in the presentation of the common (b3a2) fusion gene. HLA-B*14 and DRB1*01 showed strong LD, and all 5 patients who were positive for the presumed haplotype B*14-DRB1*01 were of age 43 years old or older (P = 0.003), suggesting a delay effect. We also examined the influence of homozygosity for DRB3 (DR52) and DRB4 (DR53) haplotypes on susceptibility. As previously shown in CML and CLL, DRB4 homozygosity was a risk marker (P = 0.01; OR = 3.36), and DRB3 homozygosity was protective (P = 0.007; OR = 0.51). Despite the lack of elderly patients in the study group, the opposite accelerating (DRB4) and delaying (DRB3) effects of homozygous genotypes on the age-at-onset were evident. Besides replicating previously found associations in a different population, this study also suggested new, and probably population-specific associations in CML. The mechanisms by which the HLA system modifies susceptibility to CML are unknown, likely to include immune and nonimmune ones, and worthy of further studies.

Environmental pollutants and breast cancer

Breast cancer is the most common cancer in women and the leading cause of cancer death among women 35-54 years of age. Rising incidence, increased risk among migrants to higher risk regions, and poor prediction of individual risk have prompted a search for additional modifiable factors. Risk factors for breast cancer include reproductive characteristics associated with estrogen and other hormones, pharmaceutical hormones, and activities such as alcohol use and lack of exercise that affect hormone levels. As a result, investigation of hormonally active compounds in commercial products and pollution is a priority. Compounds that cause mammary tumors in animals are additional priorities. Animal models provide insight into possible mechanisms for effects of environmental pollutants on breast cancer and identify chemical exposures to target in epidemiologic studies. Although few epidemiologic studies have been conducted for chemical exposures, occupational studies show associations between breast cancer and exposure to certain organic solvents and polycyclic aromatic hydrocarbons (PAHs). Population-based studies have been limited to a few organochlorine compounds and PAHs and have been mostly negative. A variety of challenges in studies of breast cancer and the environment may have contributed to negative findings. Lack of exposure assessment tools and few hypothesis-generating toxicologic studies limit the scope of epidemiologic studies. Issues of timing with respect to latency and periods of breast vulnerability, and individual differences in susceptibility pose other challenges. Substantial work is needed in exposure assessment, toxicology, and susceptibility before we can expect a pay-off from large epidemiologic studies of breast cancer and environment.

Androgen-dependent regulation of human MUC1 mucin expression

MUC1 mucin is transcriptionally regulated by estrogen, progesterone, and glucocorticoids. Our objective was to determine whether androgen receptor (AR) activation regulates expression of MUC1. The following breast and prostatic cell lines were phenotyped and grouped according to AR and MUC1 protein expression: 1) AR+MUC1 + [DAR17+19 (AR transfectants of DU-145), ZR-75-1, MDA-MB-453, and T47D]; 2) AR-MUC1 + [DZeo1 (AR-vector control), DU-145, BT20, MDA-MB-231, and MCF7]; 3) AR+MUC1 - (LNCaP and LNCaP-r). Cell proliferation was determined using the MTT assay in the presence of synthetic androgen R1881, 0.1 microM to 1 microM. Cell surface MUC1 expression was determined by flow cytometry in the presence or absence of oestradiol, medroxy progesterone acetate or R1881, with and without 4 hydroxy-flutamide (4-OH), a nonsteroidal AR antagonist. The functional significance of MUC1 expression was investigated with a cell-cell aggregation assay. Only AR+MUC1 + cell lines showed a significant increase in MUC1 expression with AR activation (P (range) =.01 to .0001), reversed in the presence of 4-OHF. Cell proliferation was unaffected. Increased expression of MUC1 was associated with a significant (P (range) = .002 to .001) reduction in cell-cell adhesion. To our knowledge, this is the first description of androgen-dependent regulation of MUC1 mucin. This is also functionally associated with decreased cell-cell adhesion, a recognised feature of progressive malignancy. These findings have important implications for physiological and pathological processes.