Unifying mechanism in the initiation of breast cancer by metabolism of estrogen (Review)

Harnessing actinobacteria potential for cancer prevention and treatment

Actinobacteria are gram-positive bacteria with high G:C ratio in their genetic makeup. They have been noted and studied for their capacity to produce bioactive substances with a range of uses in human health, and they also exhibit a unique property of adapting to extreme environments quite well. Actinobacteria may play an essential role in cancer prevention and treatment due to their synthesis of anticancer compounds, as indicated by recent studies. The aim of this review is to give a summary of what is currently known about the connection between actinobacteria and different types of cancer. This paper delineates the diverse array of actinobacterial bioactive compounds possessing anticancer properties, elucidates their mechanisms of action and explores potential applications in cancer treatment. Furthermore, this review highlights how the microbiome influences the onset and progression of cancer, as well as the discussing the potential benefits that actinobacteria may bring in terms of controlling the microbiome and contributing to the regulation of the tumour microenvironment to cure or prevent cancer.

A case-control study on the association between adherence to a Mediterranean-style diet and breast cancer

Background

Previous studies on the association between diet and breast cancer are mostly from Western populations, and data from Middle East countries are scarce, where the prevalence of breast cancer is high; therefore, it ranks first among other cancers. This population-based case-control study aimed to investigate the relationship between a Mediterranean-style diet and breast cancer among Iranian women.

Methods

In the current study, 350 new cases of breast cancer and 700 age- and socioeconomic status-matched controls were enrolled. We evaluated the dietary intakes of participants by using a 106-item Willett-format semi-quantitative dish-based food frequency questionnaire (SQ-FFQ). We calculated the Mediterranean diet score according to the dietary intakes of participants. In addition, using pre-tested questionnaires, we collected information on potential confounding variables.

Results

In this study, we found a significant inverse association between the Mediterranean diet and breast cancer so that after controlling for potential confounders, individuals in the highest tertile of the Mediterranean diet score compared with those in the lowest tertile were 57% less likely to have breast cancer [odds ratio (OR): 0.43, 95% confidence interval (CI): 0.28-0.67]. Such an inverse association was also observed for postmenopausal women. Similarly, after controlling for potential confounding variables, high adherence to the Mediterranean dietary pattern was associated with lower odds of breast cancer (OR: 0.37, 95% CI: 0.23-0.60). However, this relationship was not significant among premenopausal women.

Conclusion

We found that adherence to Mediterranean dietary pattern was associated with reduced odds of breast cancer. Studies with prospective design are needed to further examine this association.

Silencing of long noncoding RNA MIAT inhibits the viability and proliferation of breast cancer cells by promoting miR-378a-5p expression

Myocardial infarction–associated transcript (MIAT) is a long noncoding RNA that plays a critical role in a variety of diseases. Accordingly, this study probed into the possible interaction mechanism between MIAT and miR-378a-5p in breast cancer. Concretely, MIAT and miR-378a-5p expressions in breast cancer tissues and cells were measured. After transfection with siMIAT and miR-378a-5p inhibitor, the viability and proliferation of breast cancer cells were examined by cell counting kit-8 and colony formation assays. The expressions of apoptosis-related proteins were detected. According to the results, MIAT was highly expressed in breast cancer tissues and cells. MIAT silencing could decrease Bcl-2 expression, viability, and proliferation of breast cancer cells and increase the expressions of cleaved caspase-3 and Bax. MIAT and miR-378a-5p could directly bind to each other, and MIAT silencing promoted the expression of miR-378a-5p. miR-378a-5p expression was low in breast cancer tissues. The miR-378a-5p inhibitor enhanced the viability and proliferation of breast cancer cells and partially reversed the effects of MIAT silencing on the breast cancer cells. In conclusion, MIAT silencing inhibits the viability and proliferation of breast cancer cells by promoting miR-378a-5p, indicating the potential of MIAT as a new target for the treatment of breast cancer.

Effect of Interaction between Chromium(VI) with 17β-Estradiol and Its Metabolites on Breast Cancer Cell Lines MCF-7/WT and MDA-MB-175-VII: Preliminary Study

The number of factors initiating and stimulating the progression of breast cancer are constantly increasing. Estrogens are a risk factor for breast adenocarcinoma, the toxicity of which increases as a result of metabolism and interaction with other factors. Due to the presence of environmental exposure to estrogens and metalloestrogens, we investigated how interactions between estrogens and toxic chromium(VI)[Cr(VI)] affect breast cancer lines and investigated whether estrogens play a protective role. The aim of the study was to investigate the effect of 17β-estradiol and its metabolites: 2-methoxyestradiol (2-MeOE2), 4-hydroxyestradiol (4-OHE2), and 16α-hydroxyestrone (16α-OHE1) in exposure to Cr(VI) on cell viability and DNA cell damage. Two estrogen-dependent breast cancer cell lines, MCF 7/WT and MDA-MB-175-VII, were examined. In addition, the expression of Cu-Zn superoxide dismutase (SOD1) was determined immunocytochemically to elucidate the mechanism of oxidative stress. The effects of single substances and their mixtures were tested in the model of simultaneous and 7-day estrogen pre-incubation. As a result, the viability of MCF-7 and MDA-MB-175-VII cells is lowered most by Cr(VI) and least by 17β-E2. In the combined action of estrogens and metalloestrogens, we observed a protective effect mainly of 17β-E2 against Cr(VI)-induced cytotoxicity. The highest expression of SOD1 was found in MCF-7/WT cells exposed to 17β-E2. Moreover, high apoptosis was caused by both Cr(VI) itself and its interaction with 4-OHE2 and 2-MeOE2. The direction and dynamics of changes in viability are consistent for both lines.

Honey: A Promising Therapeutic Supplement for the Prevention and Management of Osteoporosis and Breast Cancer

Osteoporosis and breast cancer are serious diseases that have become a significant socioeconomic burden. There are biochemical associations between the two disorders in terms of the amended function of estrogen, receptor activator of nuclear factor kappa beta ligand, oxidative stress, inflammation, and lipid accumulation. Honey as a functional food with high antioxidant and anti-inflammatory properties can contribute to the prevention of various diseases. Its health benefits are mainly related to the content of polyphenols. This review aims to summarize the current knowledge from in vitro, animal, and human studies on the use of honey as a potential therapeutic agent for osteoporosis and breast cancer. Preclinical studies have revealed a beneficial impact of honey on both bone health (microstructure, strength, oxidative stress) and breast tissue health (breast cancer cell proliferation and apoptosis, tumor growth rate, and volume). The limited number of clinical trials, especially in osteoporosis, indicates the need for further research to evaluate the potential benefits of honey in the treatment. Clinical studies related to breast cancer have revealed that honey is effective in increasing blood cell counts, interleukin-3 levels, and quality of life. In summary, honey may serve as a prospective therapeutic supplement for bone and breast tissue health.

The Interplay of GPER1 with 17β-Aminoestrogens in the Regulation of the Proliferation of Cervical and Breast Cancer Cells: A Pharmacological Approach

The G-protein-coupled receptor for estrogen (GPER1) is a transmembrane receptor involved in the progression and development of various neoplasms whose ligand is estradiol (E2). 17β-aminoestrogens (17β-AEs) compounds, analogs to E2, are possible candidates for use in hormone replacement therapy (HRT), but our knowledge of their pharmacological profile is limited. Thus, we explored the molecular recognition of GPER1 with different synthetic 17β-AEs: prolame, butolame, and pentolame. We compared the structure and ligand recognition sites previously reported for a specific agonist (G1), antagonists (G15 and G36), and the natural ligand (E2). Then, the biological effects of 17β-AEs were analyzed through cell viability and cell-cycle assays in two types of female cancer. In addition, the effect of 17β-AEs on the phosphorylation of the oncoprotein c-fos was evaluated, because this molecule is modulated by GPER1. Molecular docking analysis showed that 17β-AEs interacted with GPER1, suggesting that prolame joins GPER1 in a hydrophobic cavity, similarly to G1, G15, and E2. Prolame induced cell proliferation in breast (MCF-7) and cervical cancer (SIHA) cells; meanwhile, butolame and pentolame did not affect cell proliferation. Neither 17β-AEs nor E2 changed the activation of c-fos in MCF-7 cells. Meanwhile, in SIHA cells, E2 and 17β-AEs reduced c-fos phosphorylation. Thus, our data suggest that butolame and pentolame, but not prolame, could be used for HRT without presenting a potential risk of inducing breast- or cervical-cancer-cell proliferation. The novelty of this work lies in its study of compound analogs to E2 that may represent important therapeutic strategies for women in menopause, with non-significant effects on the cell viability of cancer cells. The research focused on the interactions of GPER1, a molecule recently associated with promoting and maintaining various neoplasms.

Psoralen downregulates osteoarthritis chondrocyte inflammation via an estrogen-like effect and attenuates osteoarthritis

Estrogen and its receptor play a positive role in the development of osteoarthritis (OA). Psoralen is a plant-derived estrogen analog. This study aimed to verify whether psoralen inhibits OA through an estrogen-like effect. First, human primary chondrocytes in the late stage of OA were extracted to complete collagen type II immunofluorescence staining and cell proliferation experiments. Subsequently, estrogen, psoralen and estrogen receptor antagonists were co-cultured with OA chondrocytes, and RT-PCR was performed to detect the gene expression. A rabbit OA model was subsequently made by anterior cruciate ligament transection (ACLT). They were set as Sham group, OA group and Psoralen group, respectively. The articular cartilage samples were taken after 5 weeks of treatment, and the effect was observed by gross observation, histological staining, micro-CT scanning of subchondral bone. The results of cellular experiments displayed that the cultured cells were positive for collagen II fluorescence staining and 12 μg/mL psoralen was selected as the optimal concentration. In addition, psoralen had effects similar to estrogen, promoting the expression of estrogen tar-get genes CTSD, PGR and TFF1 and decreasing the expression of the inflammation-related gene TNF- α, IL-1β and IL-6. The effect of psoralen was blocked after the use of an estrogen receptor antagonist. Further animal experiments indicated that the psoralen group showed less destruction of cartilage tissue and decreased OASRI scores compared with the OA group. A subchondral bone CT scan demonstrated that psoralen significantly increased subchondral bone mineral density (BMD), trabecular thickness and trabecular number and decreased trabecular separation. In summary, psoralen inhibits the inflammatory production of chondrocytes, which is related to estrogen-like effect, and can be used to attenuate the progression of OA.

Role of the Mediator Complex and MicroRNAs in Breast Cancer Etiology

Transcriptional coactivators play a key role in RNA polymerase II transcription and gene regulation. One of the most important transcriptional coactivators is the Mediator (MED) complex, which is an evolutionary conserved large multiprotein complex. MED transduces the signal between DNA-bound transcriptional activators (gene-specific transcription factors) to the RNA polymerase II transcription machinery to activate transcription. It is known that MED plays an essential role in ER-mediated gene expression mainly through the MED1 subunit, since estrogen receptor (ER) can interact with MED1 by specific protein–protein interactions; therefore, MED1 plays a fundamental role in ER-positive breast cancer (BC) etiology. Additionally, other MED subunits also play a role in BC etiology. On the other hand, microRNAs (miRNAs) are a family of small non-coding RNAs, which can regulate gene expression at the post-transcriptional level by binding in a sequence-specific fashion at the 3′ UTR of the messenger RNA. The miRNAs are also important factors that influence oncogenic signaling in BC by acting as both tumor suppressors and oncogenes. Moreover, miRNAs are involved in endocrine therapy resistance of BC, specifically to tamoxifen, a drug that is used to target ER signaling. In metazoans, very little is known about the transcriptional regulation of miRNA by the MED complex and less about the transcriptional regulation of miRNAs involved in BC initiation and progression. Recently, it has been shown that MED1 is able to regulate the transcription of the ER-dependent miR-191/425 cluster promoting BC cell proliferation and migration. In this review, we will discuss the role of MED1 transcriptional coactivator in the etiology of BC and in endocrine therapy-resistance of BC and also the contribution of other MED subunits to BC development, progression and metastasis. Lastly, we identified miRNAs that potentially can regulate the expression of MED subunits.

Insights into the Behavior of Triple-Negative MDA-MB-231 Breast Carcinoma Cells Following the Treatment with 17β-Ethinylestradiol and Levonorgestrel

Oral contraceptives (OCs) are widely used due to their efficiency in preventing unplanned pregnancies and treating several human illnesses. Despite their medical value, the toxicity of OCs remains a public concern. Previous studies indicate the carcinogenic potential of synthetic sex hormones and their link to the development and progression of hormone-dependent malignancies such as breast cancer. However, little is known about their influence on the evolution of triple-negative breast carcinoma (TNBC), a malignancy defined by the absence of estrogen, progesterone, and HER2 receptors. This study reveals that the active ingredients of modern OCs, 17β-Ethinylestradiol, Levonorgestrel, and their combination induce differential effects in MDA-MB-231 TNBC cells. The most relevant behavioral changes occurred after the 24 h treatment with 17β-Ethinylestradiol, summarized as follows: (i) decreased cell viability (64.32% at 10 µM); (ii) cell roundness and loss of confluence; (iii) apoptotic aspect of cell nuclei (fragmentation, membrane blebbing); and (iv) inhibited cell migration, suggesting a potential anticancer effect. Conversely, Levonorgestrel was generally associated with a proliferative activity. The association of the two OCs exerted similar effects as 17β-Ethinylestradiol but was less effective. Further studies are necessary to elucidate the hormones' cytotoxic mechanism of action on TNBC cells.

Influence of Estrogenic Metabolic Pathway Genes Polymorphisms on Postmenopausal Breast Cancer Risk

Estrogen metabolism plays an important role in tumor initiation and development. Lifetime exposure to high estrogens levels and deregulation of enzymes involved in estrogen biosynthetic and metabolic pathway are considered risk factors for breast cancer. The present study aimed to evaluate the impact of mutations acquisition during the lifetime in low penetrance genes that codify enzymes responsible for estrogen detoxification. Genotype analysis of GSTM1 and GSTT1 null polymorphisms, CYP1B1 Val432Leu and MTHFR C677T polymorphisms was performed in 157 samples of women with hormone-dependent breast cancer and correlated with the age at diagnosis. The majority of patients with GSTT1 null genotype and with both GSTM1 and GSTT1 null genotypes were 50 years old or more at the diagnosis (p-value = 0.021 and 0.018, respectively). Older women with GSTM1 null genotype were also carriers of the CYP1B1Val allele (p-value = 0.012). As well, GSTT1 null and CYP1B1Val genotypes were correlated with diagnosis at later ages (p-value = 0.022). Similar results were found associating MTHFR C677T and GSTT1 null polymorphism (p-value = 0.034). Our results suggest that estrogen metabolic pathway polymorphisms constitute a factor to be considered simultaneously with models for breast cancer risk assessment.

Physical Activity as an Imperative Support in Breast Cancer Management

Breast cancer (BC) is the most common malignancy and the second cause of cancer-related death among women. It is estimated that 9 in 10 cases of BC are due to non-genetic factors, and approximately 25% to 30% of total breast cancer cases should be preventable only by lifestyle interventions. In this context, physical activity represents an excellent and accessible approach not only for the prevention, but also for being a potential support in the management of breast cancer. The present review will collect the current knowledge of physical activity in the background of breast cancer, exploring its systemic and molecular effects, considering important variables in the training of these women and the evidence regarding the benefits of exercise on breast cancer survival and prognosis. We will also summarize the various effects of physical activity as a co-adjuvant therapy in women receiving different treatments to deal with its adverse effects. Finally, we will reveal the impact of physical activity in the enhancement of quality of life of these patients, to conclude the central role that exercise must occupy in breast cancer management, in an adequate context of a healthy lifestyle.

Mitochondrial Dysfunction Induced by High Estradiol Concentrations in Endometrial Epithelial Cells

CONTEXT

A supraphysiological estradiol (E2) concentration after ovarian stimulation is known to result in lower embryo implantation rates in in vitro fertilization. Endometrial epithelial cell (EEC) apoptosis occurs after the stimulation with high E2 concentrations, and mitochondria play important roles in cell apoptosis.

OBJECTIVE

To investigate the mitochondrial function in EECs after the stimulation with high E2 concentrations.

MATERIALS AND METHODS

Human EECs were purified and cultured with different E2 concentrations (10-10, 10-9, 10-8, 10-7 M) in vitro, in which 10-7 M is supraphysiologically high. Eight-week-old female mouse endometrium was obtained 5.5 days after the injection of 1.25 IU or 20 IU equine chorionic gonadotropin, roughly during the embryo implantation window, to examine the in vivo effects of high E2 concentrations on mouse EECs.

RESULTS

In vivo and in vitro experiments demonstrated decreased mitochondrial DNA contents and ATP formation after EECs were stimulated with supraphysiologically high E2 concentrations than those stimulated with a physiologic E2 concentration. Less prominent immunofluorescence mitochondrial staining, fewer mitochondria numbers under electron microscopy, lower 5,5',6,6'-tetrachloro-1,1',3,3'-tetraethylbenzimidazolylcarbocyanine iodide aggregate/monomer ratio, and greater reactive oxygen species (ROS) production were found after EECs were stimulated with supraphysiologically high E2 concentrations. The high E2-induced ROS production was reduced when EECs were pretreated with N-acetyl-cysteine in vitro, but remained unchanged after the pretreatment with coenzyme Q10.

CONCLUSION

High E2 concentrations increase extramitochondrial ROS production in EECs and subsequently result in mitochondrial dysfunction.

Obesity, DNA Damage, and Development of Obesity-Related Diseases

Obesity has been recognized to increase the risk of such diseases as cardiovascular diseases, diabetes, and cancer. It indicates that obesity can impact genome stability. Oxidative stress and inflammation, commonly occurring in obesity, can induce DNA damage and inhibit DNA repair mechanisms. Accumulation of DNA damage can lead to an enhanced mutation rate and can alter gene expression resulting in disturbances in cell metabolism. Obesity-associated DNA damage can promote cancer growth by favoring cancer cell proliferation and migration, and resistance to apoptosis. Estimation of the DNA damage and/or disturbances in DNA repair could be potentially useful in the risk assessment and prevention of obesity-associated metabolic disorders as well as cancers. DNA damage in people with obesity appears to be reversible and both weight loss and improvement of dietary habits and diet composition can affect genome stability.

Bone Mineral Density and Breast Cancer Incidence and Mortality in Postmenopausal Women: A Long-Term Follow-Up Study

Purpose: To examine whether bone mineral density (BMD) is predictive of breast cancer risk and mortality in a population of early postmenopausal women participating in a medical prevention program in western Austria. Patients and Methods: Between May 1991 and February 1999, lumbar spine BMD was measured by dual-energy X-ray absorptiometry (N = 1163, mean age 56.9 ± 5.7 years) or quantitative computed tomography (N = 2283, mean age 56.8 ± 5.4 years) in 3446 women aged ≥50 years. Data on medication and lifestyle factors were collected by questionnaire. Participants were prospectively followed up for breast cancer incidence, and breast cancer patients were followed up for mortality. To calculate risk of breast cancer and mortality, Cox proportional hazards models were applied. Results: During median follow-up of 20.7 years, 185 invasive breast cancer cases and 22 deaths due to breast cancer occurred. Risk of breast cancer in the highest versus the lowest BMD quartile was nonsignificantly reduced, in particular when follow-up was restricted to 10 years (hazard ratio 0.53, 95% confidence interval 0.25-1.12). There was no risk reduction when follow-up began 10 years after BMD measurement. There was no association between BMD and all-cause or breast cancer-specific mortality among breast cancer patients, but a trend toward reduced mortality risk in the highest BMD quartile. Conclusions: We hypothesize that BMD is not reflective of estrogen exposure and not predictive of breast cancer risk, at least in young postmenopausal women. Confounders such as vitamin D might underlie low breast cancer risk at high BMD, thus mirroring better health status.