Antihormones in Prevention and Treatment of Breast Cancer

Involvement of glutathione peroxidases in the occurrence and development of breast cancers

Glutathione peroxidases (GPxs) belong to a family of enzymes that is important in organisms; these enzymes promote hydrogen peroxide metabolism and protect cell membrane structure and function from oxidative damage. Based on the establishment and development of the theory of the pathological roles of free radicals, the role of GPxs has gradually attracted researchers' attention, and the involvement of GPxs in the occurrence and development of malignant tumors has been shown. On the other hand, the incidence of breast cancer in increasing, and breast cancer has become the leading cause of cancer-related death in females worldwide; breast cancer is thought to be related to the increased production of reactive oxygen species, indicating the involvement of GPxs in these processes. Therefore, this article focused on the molecular mechanism and function of GPxs in the occurrence and development of breast cancer to understand their role in breast cancer and to provide a new theoretical basis for the treatment of breast cancer.

Rutin and orlistat produce antitumor effects via antioxidant and apoptotic actions

Cancer is a broad term used to describe a large number of diseases characterized by uncontrolled cell proliferation that leads to tumor production. Cancer is associated with mutations in genes controlling proliferation and apoptosis, oxidative stress, fatty acid synthase (FAS) expression, and other mechanisms. Currently, most antineoplastic drugs have severe adverse effects and new effective and safe drugs are needed. This study aims to investigate the possible anticancer activity of rutin and orlistat which are both safely used clinically in humans against two breast cancer models (in vivo EAC and in vitro MCF7) and the pancreatic cancer cell line (PANC-1). Our results have shown that both rutin and orlistat exerted an in vivo anticancer activity as evidenced by the decrease in tumor volume, CEA level, cholesterol content, FAS, and the exerted antioxidant action (reduced MDA level and increased GSH content) and through histopathological examination. In addition, both were cytotoxic to MCF-7 and Panc-1 cell lines by promoting apoptosis. In conclusion, the anticancer activity of rutin and orlistat makes them promising candidates for cancer treatment alone or in combination with other anticancer drugs specially that they are used clinically with an acceptable safety profile.

G-1 Inhibits Breast Cancer Cell Growth via Targeting Colchicine-Binding Site of Tubulin to Interfere with Microtubule Assembly

G-protein-coupled estrogen receptor 1 (GPER1) has been reported to play a significant role in mediating the rapid estrogen actions in a wide range of normal and cancer cells. G-1 was initially developed as a selective agonist for GPER. However, the molecular mechanisms underlying the actions of G-1 are unknown, and recent studies report inconsistent effects of G-1 on the growth of breast cancer cells. By employing high-resolution laser scanning confocal microscopy and time-lapse imaging technology, as well as biochemical analyses, in the current study, we provide convincing in vitro and in vivo evidence that G-1 is able to suppress the growth of breast cancer cells independent of the expression status of GPERs and classic estrogen receptors. Interestingly, we found that triple-negative breast cancer cells (TNBC) are very sensitive to G-1 treatment. We found that G-1 arrested the cell cycle in the prophase of mitosis, leading to caspase activation and apoptosis of breast cancer cells. Our mechanistic studies indicated that G-1, similar to colchicine and 2-methoxyestradiol, binds to colchicine binding site on tubulin, inhibiting tubulin polymerization and subsequent assembly of normal mitotic spindle apparatus during breast cancer cell mitosis. Therefore, G-1 is a novel microtubule-targeting agent and could be a promising anti-microtubule drug for breast cancer treatment, especially for TNBC treatment. Mol Cancer Ther; 16(6); 1080-91. ©2017 AACR.

Simultaneous disruption of estrogen receptor and Wnt/β-catenin signaling is involved in methyl amooranin-mediated chemoprevention of mammary gland carcinogenesis in rats

Methyl-amoorain (methyl-25-hydroxy-3-oxoo-lean-12-en-28-oate, AMR-Me), a novel synthetic oleanane triterpenoid, exerts a striking chemopreventive effect against 7,12-dimethylbenz(a)anthracene (DMBA)-induced rat mammary tumorigenesis through antiproliferative and proapoptotic actions. Nevertheless, the underlying mechanisms of action remain to be established. As estrogen receptor (ER) and canonical Wnt/b-catenin signaling are involved in the development and progression of breast cancer, the current study was designed to investigate the effects of AMR-Me treatment on the expressions of ER-a, ER-b, b-catenin and cyclin D1 in rat mammary tumors induced by DMBA. Mammary tumor samples were harvested from an 18-week chemopreventive study in which AMR-Me (0.8–1.6 mg/kg) was shown to inhibit mammary carcinogenesis in a dose–response manner. The expressions of ER-a, ER-b, b-catenin, and cyclin D1 were determined by immunohistochemistry and reverse transcription-polymerase chain reaction. AMR-Me downregulated the expression of intratumor ER-a and ER-b and lowered the ratio of ER-a to ER-b. AMR-Me also reduced the expression, cytoplasmic accumulation, and nuclear translocation of b-catenin, the essential transcriptional cofactor for Wnt signaling. Furthermore, AMR-Me modulated the expression of cell growth regulatory gene cyclin D1, which is a downstream target for both ER and Wnt signaling. AMR-Me at 1.6 mg/kg for 18 weeks did not exhibit any hepatotoxicity or renotoxicity. The results of the present study coupled with our previous findings indicate that simultaneous disruption of ER and Wnt/b-catenin signaling possibly contributes to antiproliferative and apoptosis-inducing effects implicated in AMR-Me-mediated chemoprevention of DMBA-induced breast tumorigenesis in rats. Our results also suggest a possible crosstalk between two key regulatory pathways, namely ER and Wnt/b-catenin signaling, involved in mammary carcinogenesis and the value of simultaneously targeting these pathways to achieve breast cancer chemoprevention.

Anti-Proliferative Effects of Evodiamine on Human Breast Cancer Cells

Endocrine sensitivity, assessed by the expression of estrogen receptor (ER), has long been the predict factor to guide therapeutic decisions. Tamoxifen has been the most successful hormonal treatment in endocrine-sensitive breast cancer. However, in estrogen-insensitive cancer tamoxifen showed less effectiveness than in estrogen-sensitive cancer. It is interesting to develop new drugs against both hormone-sensitive and insensitive tumor. In this present study we examined anticancer effects of evodiamine extracted from the Chinese herb, Evodiae fructus, in estrogen-dependent and –independent human breast cancer cells, MCF-7 and MDA-MB-231 cells, respectively. Evodiamine inhibited the proliferation of MCF-7 and MDA-MB-231 cells in a concentration-dependent manner with concentration of 1×10⁻⁶ and 1×10⁻⁵ M. Evodiamine also induced apoptosis via up-regulation of caspase 7 activation, PARP cleavage (Bik and Bax expression). The expression of ER α and β in protein and mRNA levels was down-regulated by evodiamine according to data from immunoblotting and RT-PCR analysis. Overall, our results indicate that evodiamine mediates degradation of ER and induces caspase-dependent pathway leading to inhibit proliferation of breast cancer cell lines. It suggests that evodiamine may in part mediate through ER-inhibitory pathway to inhibit breast cancer cell proliferation.

MIBE acts as antagonist ligand of both estrogen receptor α and GPER in breast cancer cells

Introduction

The multiple biological responses to estrogens are mainly mediated by the classical estrogen receptors ERα and ERβ, which act as ligand-activated transcription factors. ERα exerts a main role in the development of breast cancer; therefore, the ER antagonist tamoxifen has been widely used although its effectiveness is limited by de novo and acquired resistance. Recently, GPR30/GPER, a member of the seven-transmembrane G protein-coupled receptor family, has been implicated in mediating the effects of estrogens in various normal and cancer cells. In particular, GPER triggered gene expression and proliferative responses induced by estrogens and even ER antagonists in hormone-sensitive tumor cells. Likewise, additional ER ligands showed the ability to bind to GPER eliciting promiscuous and, in some cases, opposite actions through the two receptors. We synthesized a novel compound (ethyl 3-[5-(2-ethoxycarbonyl-1-methylvinyloxy)-1-methyl-1H-indol-3-yl]but-2-enoate), referred to as MIBE, and investigated its properties elicited through ERα and GPER in breast cancer cells.

Methods

Molecular modeling, binding experiments and functional assays were performed in order to evaluate the biological action exerted by MIBE through ERα and GPER in MCF7 and SkBr3 breast cancer cells.

Results

MIBE displayed the ability to act as an antagonist ligand for ERα and GPER as it elicited inhibitory effects on gene transcription and growth effects by binding to both receptors in breast cancer cells. Moreover, GPER was required for epidermal growth factor receptor (EGFR) and ERK activation by EGF as ascertained by using MIBE and performing gene silencing experiments.

Conclusions

Our findings provide novel insights on the functional cross-talk between GPER and EGFR signaling. Furthermore, the exclusive antagonistic activity exerted by MIBE on ERα and GPER could represent an innovative pharmacological approach targeting breast carcinomas which express one or both receptors at the beginning and/or during tumor progression. Hence, the simultaneous inhibition of both ERα and GPER may guarantee major therapeutic benefits in respect to the use of a selective estrogen receptor antagonist.

Association of CTLA-4 gene polymorphisms with sporadic breast cancer risk and clinical features in Han women of northeast China

Cytotoxic T lymphocyte antigen-4 (CTLA-4) is an inhibitory molecule that plays a pivotal role in downregulating T-cell mediated immune responses. To determine the role of CTLA-4 in tumor immunity, and to validate previous results as well, we investigated four tag single nucleotide polymorphisms (SNPs) of CTLA-4 in a relatively large Chinese Han cohort from northeastern China. Genotypes were determined by polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) in 581 patients and 566 age-matched controls. Our data indicated that compared with the common genotype and allele of each SNP, the -1722 CC genotype and C allele showed an increased risk of breast cancer (P = 0.030, odds ratio (OR) = 1.457, 95% confidence internal (CI) 1.036-2.051; P = 0.024, OR = 1.214, 95% CI 1.026-1.436, respectively). The -1661 GG genotype and G allele were also associated with an increased risk of breast cancer (P = 0.018, OR = 1.396, 95% CI 1.058-1.843; P = 0.013, OR = 1.353, 95% CI 1.066-1.717, respectively). In the haplotype analysis, the CAAA haplotype showed a higher frequency in cases (P = 0.004), and this association remained significant after correcting the P value for multiple testing. Associations were shown between the SNPs of CTLA-4 and lymph node metastasis, estrogen receptor (ER), progesterone receptor (PR) and P53 statuses. These results indicate that some SNPs in the CTLA-4 gene may affect the risk of breast cancer and show that some SNPs are associated with breast cancer characteristics in Han women in northeastern China.

Peroxidase-mediated dealkylation of tamoxifen, detected by electrospray ionization-mass spectrometry, and activation to form DNA adducts

Tamoxifen (TAM) is extensively used for the treatment and prevention of breast cancer. Associated with TAM treatment is a two- to eightfold increase in risk of endometrial cancer. To understand the mechanisms associated with this increased risk several pathways for TAM metabolism and DNA adduct formation have been studied. The purpose of this study was to investigate the role of peroxidase enzymes in the metabolism of TAM and its activation to form DNA adducts. Using advanced tandem mass spectrometry we have investigated the peroxidase-mediated metabolism of TAM. Incubation of TAM with horseradish peroxidase (HRP) and H(2)O(2) produced multiple metabolites. Electrospray ionization-MS/MS analysis of the metabolites demonstrated a peak at 301.3m/z with daughter ions at 183.0, 166.9, 128.9, and 120.9m/z, which identified the metabolite as metabolite E (ME). The levels of ME were significantly inhibited by the addition of ascorbic acid to the incubation mixture. Co-incubation of either TAM or ME and DNA with HRP and H(2)O(2) produced three DNA adducts with a RAL of 1.97±0.01×10(-7) and 8.45±2.7×10(-7). Oxidation of ME with MnO(2) produced metabolite E quinone methide (MEQM). Furthermore, incubation of either TAM or ME with HRP and H(2)O(2) resulted in formation of MEQM. Reaction of calf thymus DNA with MEQM produced three DNA adducts with a RAL of 9.8±1.0×10(-7). Rechromatography analyses indicated that DNA adducts 1, 2, and 3 formed in the HRP activation of either TAM or ME were the same as those formed by the chemical reaction of DNA with MEQM. The results of these studies demonstrate that peroxidase enzymes can both metabolize TAM to form the primary metabolite ME and activate ME to a quinone methide intermediate, which reacts with DNA to form adducts. It is possible that peroxidase enzymes or peroxidase-like activity in endometrium could contribute to the formation of DNA damage and genotoxic effects in endometrium after TAM administration.

GPER mediates the Egr-1 expression induced by 17β-estradiol and 4-hydroxitamoxifen in breast and endometrial cancer cells

Early growth response-1 (Egr-1) is an immediate early gene involved in relevant biological events including the proliferation of diverse types of cell tumors. In a microarray analysis performed in breast cancer cells, 17β-estradiol (E2) and the estrogen receptor antagonist 4-hydroxitamoxifen (OHT) up-regulated Egr-1 through the G protein-coupled receptor named GPR30/GPER. Hence, in this study, we aimed to provide evidence regarding the ability of E2, OHT and the selective GPER ligand G-1 to regulate Egr-1 expression and function through the GPER/EGFR/ERK transduction pathway in both Ishikawa (endometrial) and SkBr3 (breast) cancer cells. Interestingly, we demonstrate that Egr-1 is involved in the transcription of genes regulating cell proliferation like CTGF and cyclin D1 and required for the proliferative effects induced by E2, OHT, and G-1 in both Ishikawa and SkBr3 cells. In addition, we show that GPER mediates the expression of Egr-1 also in carcinoma-associated fibroblasts (CAFs). Our data suggest that Egr-1 may represent an important mediator of the biological effects induced by E2 and OHT through GPER/EGFR/ERK signaling in breast and endometrial cancer cells. The results obtained in CAFs provide further evidence regarding the potential role exerted by the GPER-dependent Egr-1 up-regulation in tumor development and progression. Therefore, Egr-1 may be included among the bio-markers of estrogen and antiestrogen actions and may be considered as a further therapeutic target in both breast and endometrial tumors.

Association between acquired uniparental disomy and homozygous mutations and HER2/ER/PR status in breast cancer

Background

Genetic alterations in cellular signaling networks are a hallmark of cancer, however, effective methods to discover them are lacking. A novel form of abnormality called acquired uniparental disomy (aUPD) was recently found to pinpoint the region of mutated genes in various cancers, thereby identifying the region for next-generation sequencing.

Methods/Principal Findings

We retrieved large genomic data sets from the Gene Expression Omnibus database to perform genome-wide analysis of aUPD in breast tumor samples and cell lines using approaches that can reliably detect aUPD. aUPD was identified in 52.29% of the tumor samples. The most frequent aUPD regions were located at chromosomes 2q, 3p, 5q, 9p, 9q, 10q, 11q, 13q, 14q and 17q. We evaluated the data for any correlation between the most frequent aUPD regions and HER2/neu, ER, and PR status, and found a statistically significant correlation between the recurrent regions of aUPD and triple negative (TN) breast cancers. aUPD at chromosome 17q (VEZF1, WNT3), 3p (SUMF1, GRM7), 9p (MTAP, NFIB) and 11q (CASP1, CASP4, CASP5) are predictors for TN. The frequency of aUPD was found to be significantly higher in TN breast cancer cases compared to HER2/neu-positive and/or ER or PR-positive cases. Furthermore, using previously published mutation data, we found TP53 homozygously mutated in cell lines having aUPD in that locus.

Conclusions/Significance

We conclude that aUPD is a common and non-random molecular feature of breast cancer that is most prominent in triple negative cases. As aUPD regions are different among the main pathological subtypes, specific aUPD regions may aid the sub-classification of breast cancer. In addition, we provide statistical support using TP53 as an example that identifying aUPD regions can be an effective approach in finding aberrant genes. We thus conclude that a genome-wide scale analysis of aUPD regions for homozygous sequence alterations can provide valuable insights into breast tumorigenesis.

Tamoxifen as first-line treatment in a premenarchal girl with juvenile breast hypertrophy

BACKGROUND

Juvenile breast hypertrophy is uncommon and is characterized by excessive breast enlargement in the peripubertal period. The clinical entity is thought to result from increased sensitivity of mammary tissue to normal levels of circulating hormones.

CASE

Here, we report a female patient, aged 12 years and 6 months, suffering from juvenile breast hypertrophy, who presented at the third month of symptoms and benefited from tamoxifen treatment.

COMMENTS

In experienced clinics, use of tamoxifen in the treatment of juvenile breast hypertrophy during the brisk growth period may become a medical alternative to reconstructive surgery.

Reduction of breast density following tamoxifen treatment evaluated by 3-D MRI: preliminary study

This study analyzed the change in breast density in women receiving tamoxifen treatment using 3-D MRI. Sixteen women were studied. Each woman received breast MRI before and after tamoxifen. The breast and the fibroglandular tissue were segmented using a computer-assisted algorithm, based on T1-weighted images. The fibroglandular tissue volume (FV) and breast volume (BV) were measured and the ratio was calculated as the percent breast density (%BD). The changes in breast volume (ΔBV), fibroglandular tissue volume (ΔFV) and percent density (Δ%BD) between two MRI studies were analyzed and correlated with treatment duration and baseline breast density. The ΔFV showed a reduction in all 16 women. The Δ%BD showed a mean reduction of 5.8%. The reduction of FV was significantly correlated with baseline FV (P<.001) and treatment duration (P=.03). The percentage change in FV was correlated with duration (P=.049). The reduction in %BD was positively correlated with baseline %BD (P=.02). Women with higher baseline %BD showed more reduction of %BD. Three-dimensional MRI may be useful for the measurement of the small changes of ΔFV and Δ%BD after tamoxifen. These changes can potentially be used to correlate with the future reduction of cancer risk.

G protein-coupled receptor 30 expression is up-regulated by EGF and TGF alpha in estrogen receptor alpha-positive cancer cells

In the present study, we evaluated the regulation of G protein-coupled receptor (GPR)30 expression in estrogen receptor (ER)-positive endometrial, ovarian, and estrogen-sensitive, as well as tamoxifen-resistant breast cancer cells. We demonstrate that epidermal growth factor (EGF) and TGF alpha transactivate the GPR30 promoter and accordingly up-regulate GPR30 mRNA and protein levels only in endometrial and tamoxifen-resistant breast cancer cells. These effects exerted by EGF and TGF alpha were dependent on EGF receptor (EGFR) expression and activation and involved phosphorylation of the Tyr(1045) and Tyr(1173) EGFR sites. Using gene-silencing experiments and specific pharmacological inhibitors, we have ascertained that EGF and TGF alpha induce GPR30 expression through the EGFR/ERK transduction pathway, and the recruitment of c-fos to the activator protein-1 site located within GPR30 promoter sequence. Interestingly, we show that functional cross talk of GPR30 with both activated EGFR and ER alpha relies on a physical interaction among these receptors, further extending the potential of estrogen to trigger a complex stimulatory signaling network in hormone-sensitive tumors. Given that EGFR/HER2 overexpression is associated with tamoxifen resistance, our data may suggest that ligand-activated EGFR could contribute to the failure of tamoxifen therapy also by up-regulating GPR30, which in turn could facilitates the action of estrogen. In addition, important for resistance is the ability of tamoxifen to bind to and activate GPR30, the expression of which is up-regulated by EGFR activation. Our results emphasize the need for new endocrine agents able to block widespread actions of estrogen without exerting any stimulatory activity on transduction pathways shared by the steroid and growth factor-signaling networks.

CT-X antigen expression in human breast cancer

Cancer/testis (CT) genes are predominantly expressed in human germ line cells, but not somatic tissues, and frequently become activated in different cancer types. Several CT antigens have already proved to be useful biomarkers and are promising targets for therapeutic cancer vaccines. The aim of the present study was to investigate the expression of CT antigens in breast cancer. Using previously generated massively parallel signature sequencing (MPSS) data, together with 9 publicly available gene expression datasets, the expression pattern of CT antigens located on the X chromosome (CT-X) was interrogated. Whereas a minority of unselected breast cancers was found to contain CT-X transcripts, a significantly higher expression frequency was detected in estrogen and progesterone receptor (ER) negative breast cancer cell lines and primary breast carcinomas. A coordinated pattern of CT-X antigen expression was observed, with MAGEA and NY-ESO-1/CTAG1B being the most prevalent antigens. Immunohistochemical staining confirmed the correlation of CT-X antigen expression and ER negativity in breast tumors and demonstrated a trend for their coexpression with basal cell markers. Because of the limited therapeutic options for ER-negative breast cancers, vaccines based on CT-X antigens might prove to be useful.

Genetic alterations and oncogenic pathways associated with breast cancer subtypes

Breast cancers can be divided into subtypes with important implications for prognosis and treatment. We set out to characterize the genetic alterations observed in different breast cancer subtypes and to identify specific candidate genes and pathways associated with subtype biology. mRNA expression levels of estrogen receptor, progesterone receptor, and HER2 were shown to predict marker status determined by immunohistochemistry and to be effective at assigning samples to subtypes. HER2(+) cancers were shown to have the greatest frequency of high-level amplification (independent of the ERBB2 amplicon itself), but triple-negative cancers had the highest overall frequencies of copy gain. Triple-negative cancers also were shown to have more frequent loss of phosphatase and tensin homologue and mutation of RB1, which may contribute to genomic instability. We identified and validated seven regions of copy number alteration associated with different subtypes, and used integrative bioinformatics analysis to identify candidate oncogenes and tumor suppressors, including ERBB2, GRB7, MYST2, PPM1D, CCND1, HDAC2, FOXA1, and RASA1. We tested the candidate oncogene MYST2 and showed that it enhances the anchorage-independent growth of breast cancer cells. The genome-wide and region-specific differences between subtypes suggest the differential activation of oncogenic pathways.

Pharmacological "cross-inhibition" of connexin hemichannels and swelling activated anion channels

The study of ion channels has relied heavily on the use of pharmacological blocking agents. However, many of these agents have multiple effects, which may compromise interpretation of results when the affected mechanisms/pathways mediate similar functions. Volume regulated anion channels (VRAC) and connexin hemichannels can both mediate the release of glutamate and taurine, although these channels have distinct activation stimuli and hemichannels, but not VRAC, are permeable to Lucifer Yellow (LY). It has been reported that some anion channel blockers may inhibit connexin hemichannels. We further examined the effects of classic gap junction/hemichannel blockers and anion channel blockers on these channels. The typical VRAC blockers, NPPB, IAA-94, and tamoxifen blocked low divalent cation-induced glutamate and taurine release and LY loading, presumed due to hemichannel opening. The blocking action of these compounds on hemichannels was concentration dependent and fell within the same range where the drugs classically block VRACs. Conversely, carbenoxolone (CBX), the most widely used gap junction/hemichannel blocker, was an effective blocker of VRAC-mediated glutamate and taurine release, and blocked these channels at similar concentrations at which it blocked hemichannels. The CBX effect on VRACs was verified using astrocytes from connexin 43 knock out (Cx43 KO) animals. In these cells, the hypotonic induced amino acid flux was retained whereas the low divalent cation solution-induced flux was lost. These results extend our knowledge about "cross-inhibition" of VRACs and gap junctions/hemichannels by certain pharmacological agents. Given the overlap in function of these two types of channels, great care must be exerted in using pharmacological blockers to identify one channel from the other.

Initial treatment and changes in adjuvant endocrine therapy for early stage breast cancer

Clinical trials have shown that aromatase inhibitors (AIs) are an important advance in the treatment of early stage breast cancer (ESBC), but practice patterns and the impact of treatment side effects of endocrine therapy in the community setting have not been extensively explored. This retrospective chart review describes practice patterns among patients receiving adjuvant endocrine therapy for ESBC. Charts of 200 patients with confirmed stage I-IIIA breast cancer were reviewed. Patients received first-line treatment with tamoxifen (n=96) or AIs (n=104). Fifty-one patients completed a structured interview regarding symptom burden during therapy. Time to discontinuation or switching from first-line therapy did not vary by drug class (tamoxifen vs. AI). Musculoskeletal symptoms predicted time to switching among AI patients. Tamoxifen patients who switched to AIs tended to do so following clinical guidelines for use of AIs. Interview results showed that more anastrozole than tamoxifen patients cited side effects as the reason for switching.

Retinal hemorrhages in anastrozole users

PURPOSE

To determine whether women using anastrozole (an aromatase inhibitor, which suppresses estrogen synthesis) are likely to have retinal hemorrhages.

METHODS

Fundus photographs were obtained for a study comparing effects on vision and the eye of anastrozole (1 mg/d) and tamoxifen (20 mg/d) for women receiving adjuvant endocrine therapy for early-stage breast cancer. Photographs (2 eyes per subject) were evaluated for hemorrhages by an ophthalmologist masked from identifying subject information. The presence of hemorrhages was assessed for 35 anastrozole users, 38 amenorrheic tamoxifen users, and 53 amenorrheic (peri- or postmenopausal) control subjects not using any endocrine medication. The age range was 43 to 69 years; only subjects reporting normal vision and healthy eyes were recruited. Photographs from 36 tamoxifen users from a previous study also were assessed. Views of the fundus extended appreciably beyond the posterior pole for all tamoxifen and anastrozole users, and for 38 of the control subjects. Photographic assessments were compared with medical history and blood pressure data, and optical coherence tomography was used for quantifying aspects of foveal shape that might be affected by vitreoretinal traction.

RESULTS

Four anastrozole users and no contemporaneous tamoxifen users but one previously tested tamoxifen user had retinal hemorrhages, in each case within the posterior pole. Two anastrozole users had a flame hemorrhage (in the retinal nerve fiber layer), and two had a blot hemorrhage (deeper in the retina). No control subjects were observed to have hemorrhages.

CONCLUSIONS

Anastrozole use appears to be associated with an increased prevalence of retinal hemorrhages. The hemorrhages may mark systemic vascular compromise resulting from estrogen depletion, and/or they may be consequences of vitreoretinal traction resulting from estrogen depletion. They may also depend on the use of medications for controlling common anastrozole-induced side effects. Prospective studies need to be conducted with larger numbers of subjects.

Tamoxifen resistance and epigenetic modifications in breast cancer cell lines

Epigenetic mechanisms play crucial roles in many processes, including neoplasia, genomic imprinting, gene silencing, differentiation, embryogenesis and X chromosome inactivation. Their relevance in human disease and therapy has grown rapidly with the recent emergence of drugs that target for example DNA methylation or histone acetylation. Epigenetic effects were also recently highlighted by the deciphering of the mechanism of action of steroid hormones and anti-hormones acting through nuclear receptors. In this review, we focus on the epigenetic effects associated with long-term treatment of breast cancer cells with the antiestrogen (AE) tamoxifen, in the context of resistance appearance. We summarize the data obtained with a model cell line developed in our laboratory supporting a role for HP1 proteins in the irreversible inactivation of gene expression by long-term treatment with AE.

The role of sex steroids and gonadectomy in the control of thymic involution

A major underlying cause for aging of the immune system is the structural and functional atrophy of the thymus, and associated decline in T cell genesis. This loss of naïve T cells reduces adaptive immunity to new stimuli and precipitates a peripheral bias to memory cells against prior antigens. Whilst multiple mechanisms may contribute to this process, the temporal alliance of thymic decline with puberty has implicated a causative role for sex steroids. Accordingly ablation of sex steroids induces profound thymic rejuvenation. Although the thymus retains some, albeit highly limited, function in healthy adults, this is insufficient for resurrecting the T cell pool following cytoablative treatments such as chemo- and radiation-therapy and AIDS. Increased risk of opportunistic infections and cancer relapse or appearance, are a direct consequence. Temporary sex steroid ablation may thus provide a clinically effective means to regenerate the thymus and immune system in immunodeficiency states.