Estrogen down regulates COMT transcription via promoter DNA methylation in human breast cancer cells

Androgens have therapeutic potential in T2 asthma by mediating METTL3 in bronchial epithelial cells

Studies have shown that androgens can alleviate the symptoms of T2 asthma and are inversely correlated with the severity of allergic asthma. METTL3, a crucial component of m6A modification, mitigates the development of T2 asthma by inhibiting Th2 cell differentiation. However, the impact of androgens, such as dihydrotestosterone (DHT), on the progression of T2 asthma through METTL3 has yet to be investigated. At the clinical level, patients with T2 asthma exhibited reduced levels of DHT and METTL3 mRNA, along with increased levels of 17β-estradiol (E2). DHT and METTL3 were found to be negatively associated with the severity of T2 asthma, while E2 was positively associated with it. Administration of DHT and E2 in induced T2 asthma mouse models showed that DHT improved lung function, reduced airway inflammation, and inhibited Th2 cell differentiation. Interestingly, DHT reversed the damage to METTL3, whereas E2 had the opposite effect. In vitro studies of mouse bronchial epithelial cells (BECs) confirmed that METTL3-dependent m6A modification inhibited the T2 inflammatory response, and DHT inhibited Th2 cell differentiation in T2 asthma by promoting METTL3 expression in BECs. In conclusion, our study suggests that DHT has therapeutic potential for T2 asthma by regulating METTL3 in BECs.

Sex dimorphism controls dysbindin-related cognitive dysfunctions in mice and humans with the contribution of COMT

Cognitive dysfunctions are core-enduring symptoms of schizophrenia, with important sex-related differences. Genetic variants of the DTBPN1 gene associated with reduced dysbindin-1 protein (Dys) expression negatively impact cognitive functions in schizophrenia through a functional epistatic interaction with Catechol-O-methyltransferase (COMT). Dys is involved in the trafficking of dopaminergic receptors, crucial for prefrontal cortex (PFC) signaling regulation. Moreover, dopamine signaling is modulated by estrogens via inhibition of COMT expression. We hypothesized a sex dimorphism in Dys-related cognitive functions dependent on COMT and estrogen levels. Our multidisciplinary approach combined behavioral-molecular findings on genetically modified mice, human postmortem Dys expression data, and in vivo fMRI during a working memory task performance. We found cognitive impairments in male mice related to genetic variants characterized by reduced Dys protein expression (pBonferroni = 0.0001), as well as in male humans through a COMT/Dys functional epistatic interaction involving PFC brain activity during working memory (t(23) = -3.21; pFDR = 0.004). Dorsolateral PFC activity was associated with lower working memory performance in males only (p = 0.04). Also, male humans showed decreased Dys expression in dorsolateral PFC during adulthood (pFDR = 0.05). Female Dys mice showed preserved cognitive performances with deficits only with a lack of estrogen tested in an ovariectomy model (pBonferroni = 0.0001), suggesting that genetic variants reducing Dys protein expression could probably become functional in females when the protective effect of estrogens is attenuated, i.e., during menopause. Overall, our results show the differential impact of functional variants of the DTBPN1 gene interacting with COMT on cognitive functions across sexes in mice and humans, underlying the importance of considering sex as a target for patient stratification and precision medicine in schizophrenia.

Importance of Using Epigenetic Nutrition and Supplements Based on Nutrigenetic Tests in Personalized Medicine

BACKGROUND

Nutrigenetics explores how genetic variations influence an individual's responses to nutrients, enabling personalized nutrition. As dietary supplements gain popularity, understanding genetic factors in their metabolism and effectiveness is crucial for optimal health outcomes. This study examines the role of genetic differences in the metabolism and effects of nutraceuticals, underscoring the significance of personalized nutrition within precision health. It aims to reveal how individual genetic profiles influence responses to dietary supplements, highlighting the value of nutrigenetics in optimizing health interventions. The study explores how genetic variations affect the absorption and effects of nutraceuticals, focusing on personalized supplement choices based on nutrigenetics.

METHODS

Sixteen patients from an Epigenetic Coaching clinic who were using supplements such as quercetin, curcumin, green tea, and sulforaphane and reporting side effects were studied. Their clinical outcomes were analyzed in relation to their supplement choices and genetic backgrounds. The study involved five women and 11 men, including eight with autism and others with conditions like Hashimoto's thyroiditis (HT) disease and joint pain.

RESULTS

In the study, it was observed that removing sulforaphane and sulfur-rich supplements from the diet of five patients reduced agitation. Removing sulforaphane and sulfur-rich supplements from the diet of four patients reduced clinical symptoms. Green tea caused discomfort in two patients. Responses to quercetin showed clinical differences in two patients. Anxiety and hyperactivity increased in three patients who took curcumin. Conclusion This study highlights the importance of considering individual genetic profiles when recommending dietary supplements. The findings suggest that personalized nutrition, guided by nutrigenetic insights, can enhance the efficacy and safety of nutraceutical interventions. Tailoring supplement choices based on genetic information can lead to better health outcomes and reduced adverse effects, emphasizing the need for integrating genetic testing into nutritional planning and healthcare practices.

CCDC12 gene methylation in peripheral blood as a potential biomarker for breast cancer detection

BACKGROUND

Aberrant DNA methylation has been identified as biomarkers for breast cancer detection. Coiled-coil domain containing 12 gene (CCDC12) implicated in tumorigenesis. This study aims to investigate the potential of blood-based CCDC12 methylation for breast cancer detection.

METHODS

DNA methylation level of CpG sites (Cytosine-phosphate Guanine dinucleotides) in CCDC12 gene was measured by mass spectrometry in 255 breast cancer patients, 155 patients with benign breast nodules and 302 healthy controls. The association between CCDC12 methylation and breast cancer risk was evaluated by logistic regression and receiver operating characteristic curve analysis.

RESULTS

A total of eleven CpG sites were analyzed. The CCDC12 methylation levels were higher in breast cancer patients. Compared to the lowest tertile of methylation level in CpG_6,7, CpG_10 and CpG_11, the highest quartile was associated with 82, 91 and 95% increased breast cancer risk, respectively. The CCDC12 methylation levels were associated with estrogen receptor (ER) and human epidermal growth factor 2 (HER2) status. In ER-negative and HER2-positive (ER-/HER2+) breast cancer subtype, the combination of four sites CpG_2, CpG_5, CpG_6,7 and CpG_11 methylation levels could distinguish ER-/HER2+ breast cancer from the controls (AUC = 0.727).

CONCLUSION

The hypermethylation levels of CCDC12 in peripheral blood could be used for breast cancer detection.

PAX2 is regulated by estrogen/progesterone through promoter methylation in endometrioid adenocarcinoma and has an important role in carcinogenesis via the AKT/mTOR signaling pathway

Endometrioid adenocarcinoma (EEC) is one of the most common cancers of the female reproductive system. In recent years, much emphasis has been placed on early diagnosis and treatment. PAX2 (Paired box 2) inactivation is reportedly an important biomarker for endometrioid intraepithelial neoplasia (EIN) and EEC. However, the role of PAX2 in EEC carcinogenesis remains unclear. PAX2 expression and associated clinical characteristics were analyzed via The Cancer Genome Atlas, Gene Expression Omnibus, and Cancer Cell Line Encyclopedia databases and clinical paired EIN/EEC tissue samples. Bioinformatic analysis was conducted to identify the putative molecular function and mechanism of PAX2. Cell proliferation, colony formation, cell migration, and invasion assays in vitro, and mouse xenograft models were utilized to study the biological functions of PAX2 in vivo. Pyrosequencing and the demethylating drug 5-Aza-dc were used to verify promoter methylation in clinical tissues and cell lines, respectively. The mechanism underlying the regulatory effect of estrogen (E2) and progesterone (P4) on PAX2 expression was investigated by receptor block assay and double luciferase reporter assay. PAX2 expression was found to be significantly downregulated in EIN and EEC tissues, its overexpression inhibited EEC cell malignant behaviors in vivo and in vitro and inhibited the AKT/mTOR signaling pathway. PAX2 inactivation in EEC was related to promoter methylation, and its expression was regulated by E2 and P4 through their receptors via promoter methylation. Our findings elucidated the expression and function of PAX2 in EEC and have provided hitherto undocumented evidence of the underlying molecular mechanisms. PAX2 expression is suppressed by estrogen prompting its methylation through estrogen receptor. Furthermore, PAX2 regulates the AKT/mTOR signaling pathway to influence EEC progression. © 2024 The Pathological Society of Great Britain and Ireland.

Effects of sulforaphane on breast cancer based on metabolome and microbiome

Sulforaphane (SFN) is a promising phytochemical with a wide range of antitumor activities. A comprehensive understanding of the effects of SFN on breast cancer based on the metabolome and microbiome is limited. Thus, we treated MCF-7 cell-transplanted nude mice with 50 mg/kg SFN. SFN inhibits breast cancer cell proliferation. SFN increased the levels of sulfate-related metabolites and glutathione-related metabolites and decreased tryptophan metabolites and methyl-purine metabolites in urinary metabolic profile. SFN indirectly affected the activation of aryl hydrocarbon receptor by tryptophan metabolism. The ratio of SAM to methionine was decreased by SFN while the global DNA methylation was downregulated in tumor tissue. SFN decreased the sulfate-reducing bacterium Desulfovibrio, which is related to reduced methylation capacity, and increased the genus Lactobacillus related to tryptophan metabolites with antitumor activities. In conclusion, we provide a perspective on the metabolome and microbiome to elucidate the antitumor activities of SFN.

Ectopic expression of MmSERT, a mouse serotonin transporter gene, regulates salt tolerance and ABA sensitivity in apple and Arabidopsis

5-hydroxytryptamine (5-HT) is ubiquitously present in animals and plants, playing a vital regulatory role. SERT, a conserved serotonin reuptake transporter in animals, regulates intracellular and extracellular concentrations of 5-HT. Few studies have reported 5-HT transporters in plants. Hence, we cloned MmSERT, a serotonin reuptake transporter, from Mus musculus. Ectopic expression of MmSERT into apple calli, apple roots and Arabidopsis. Because 5-HT plays a momentous role in plant stress tolerance, we used MmSERT transgenic materials for stress treatment. We found that MmSERT transgenic materials, including apple calli, apple roots and Arabidopsis, exhibited a stronger salt tolerance phenotype. The reactive oxygen species (ROS) produced were significantly lower in MmSERT transgenic materials compared with controls under salt stress. Meanwhile, MmSERT induced the expression of SOS1, SOS3, NHX1, LEA5 and LTP1 in response to salt stress. 5-HT is the precursor of melatonin, which regulates plant growth under adversity and effectively scavenges ROS. Detection of MmSERT transgenic apple calli and Arabidopsis revealed higher melatonin levels than controls. Besides, MmSERT decreased the sensitivity of apple calli and Arabidopsis to abscisic acid (ABA). In summary, these results demonstrated that MmSERT plays a vital role in plant stress resistances, which perhaps serves as a reference for the application of transgenic technology to improve crops in the future.

Ectopic expression of MmCYP1A1, a mouse cytochrome P450 gene, positively regulates stress tolerance in apple calli and Arabidopsis

Ectopic expression of MmCYP1A1 gene from Mus musculus in apple calli and Arabidopsis increased the levels of melatonin and 6-hydroxymelatonin, and improved their stress resistance. Melatonin occurs widely in organisms, playing a key regulatory role. CYP1A1 is a cytochrome P450 monooxygenase, involved in the melatonin metabolism, and is responsible for the synthesis of 6-hydroxymelatonin from melatonin. Melatonin and 6-hydroxymelatonin have strong antioxidant activities in animals. Here, we cloned MmCYP1A1 from Mus musculus and found that ectopic expression of MmCYP1A1 improved the levels of melatonin and 6-hydroxymelatonin in transgenic apple calli and Arabidopsis. Subsequently, we observed that MmCYP1A1 increased the tolerance of transgenic apple calli and Arabidopsis to osmotic stress simulated by polyethylene glycol 6000 (PEG 6000), as well as resistance of transgenic Arabidopsis to drought stress. Further, the number of lateral roots of MmCYP1A1 transgenic Arabidopsis were enhanced significantly after PEG 6000 treatment. The expression of MmCYP1A1 remarkably reduced malondialdehyde (MDA) content, electrolyte leakage, accumulation of H₂O₂ and O₂^- during stress treatment. Moreover, MmCYP1A1 enhanced stress tolerance in apple calli and Arabidopsis by increasing the expression levels of resistance genes. MmCYP1A1 also promoted stomatal closure in transgenic Arabidopsis to reduce leaf water loss during drought. Our results indicate that MmCYP1A1 plays a key role in plant stress tolerance, which may provide a reference for future plant stress tolerance studies.

Catechol-O-methyl transferase suppresses cell invasion and interplays with MET signaling in estrogen dependent breast cancer

Catechol-O-methyl transferase (COMT) is involved in detoxification of catechol estrogens, playing cancer-protective role in cells producing or utilizing estrogen. Moreover, COMT suppressed migration potential of breast cancer (BC) cells. To delineate COMT role in metastasis of estrogen receptor (ER) dependent BC, we investigated the effect of COMT overexpression on invasion, transcriptome, proteome and interactome of MCF7 cells, a luminal A BC model, stably transduced with lentiviral vector carrying COMT gene (MCF7-COMT). 2D and 3D assays revealed that COMT overexpression associates with decreased cell invasion (p < 0.0001 for Transwell assay, p < 0.05 for spheroid formation). RNA-Seq and LC-DIA-MS/MS proteomics identified genes associated with invasion (FTO, PIR, TACSTD2, ANXA3, KRT80, S100P, PREX1, CLEC3A, LCP1) being downregulated in MCF7-COMT cells, while genes associated with less aggressive phenotype (RBPMS, ROBO2, SELENBP, EPB41L2) were upregulated both at transcript (|log2FC|> 1, adj. p < 0.05) and protein (|log2FC|> 0.58, q < 0.05) levels. Importantly, proteins driving MET signaling were less abundant in COMT overexpressing cells, and pull-down confirmed interaction between COMT and Kunitz-type protease inhibitor 2 (SPINT2), a negative regulator of MET (log2FC = 5.10, q = 1.04-7). In conclusion, COMT may act as tumor suppressor in ER dependent BC not only by detoxification of catechol estrogens but also by suppressing cell invasion and interplay with MET pathway.

PAH-induced metabolic changes related to inflammation in childhood asthma

Epidemiological studies have shown that PAHs may exert adverse effects on childhood asthma. However, the underlying molecular mechanism remains to be fully elucidated. This study aimed to investigate this process in view of metabolic pathways, especially one-carbon metabolism and tryptophan metabolism. Fifty asthmatic children and 50 control subjects were recruited for this study. Serum IgE and IL-17A levels were detected by ELISA. Serum PAH concentrations were measured by GC-MS. One-carbon-related metabolites and tryptophan metabolites were determined by UPLC-Orbitrap-MS. DNA methylation was analyzed by bisulfite sequencing PCR. ChIP assays were used to examine H3K4me3 enrichment on IL-17A gene. Multivariable linear regression was performed to evaluate the association between PAHs and childhood asthma mediated by intermediators. HE staining in lung tissue, IgE and IL-17A in BALF, metabolic profiles in urine, and Ahr, Il-17a, and Cyp1a1 gene expression were determined in PAH-exposed mice. Serum Fla level was associated with childhood asthma (OR = 1.380, 95% CI: 1.063-1.792), and had a great effect on one-carbon metabolites, especially SAH, SAM, and Ser, which exerted significant mediation effects on the relationship between the Fla concentration and asthma. Moreover, we did find significant mediation effects between serum Fla and asthma by LINE-1 DNA methylation and H3K4me3 levels in the IL-17A promoter region. The differential Trp metabolites, such as Trp, tryptamine, IA, IAA, indole, IAld, and IAAld, indicated that asthmatic children had increased indole-AhR pathway. Mediation analysis failed to show a mediator effect of Trp metabolites in the association between PAHs and childhood asthma. An animal study confirmed that PAH exposure increased methylation levels, and altered Trp metabolite-AhR-IL-17A axis, which may be influenced by gender. PAHs disturbed one-carbon metabolism to influence the methyl group refilling DNA methylation and histone methylation, and disturbed tryptophan metabolism to regulate Th17-cell differentiation, which may elevate serum IL-17A concentration in asthmatic children.

Genetic and epigenetic regulation of Catechol-O-methyltransferase in relation to inflammation in chronic fatigue syndrome and Fibromyalgia

BACKGROUND

Catechol-O-methyltransferase (COMT) has been shown to influence clinical pain, descending modulation, and exercise-induced symptom worsening. COMT regulates nociceptive processing and inflammation, key pathophysiological features of Chronic Fatigue Syndrome and Fibromyalgia (CFS/FM). We aimed to determine the interactions between genetic and epigenetic mechanisms regulating COMT and its influence on inflammatory markers and symptoms in patients with CFS/FM.

METHODS

A case-control study with repeated-measures design was used to reduce the chance of false positive and increase the power of our findings. Fifty-four participants (28 patients with CFS/FM and 26 controls) were assessed twice within 4 days. The assessment included clinical questionnaires, neurophysiological assessment (pain thresholds, temporal summation, and conditioned pain modulation), and blood withdrawal in order to assess rs4818, rs4633, and rs4680 COMT polymorphisms and perform haplotype estimation, DNA methylation in the COMT gene (both MB-COMT and S-COMT promoters), and cytokine expression (TNF-α, IFN-γ, IL-6, and TGF-β).

RESULTS

COMT haplotypes were associated with DNA methylation in the S-COMT promoter, TGF-β expression, and symptoms. However, this was not specific for one condition. Significant between-group differences were found for increased DNA methylation in the MB-COMT promoter and decreased IFN-γ expression in patients.

DISCUSSION

Our results are consistent with basic and clinical research, providing interesting insights into genetic-epigenetic regulatory mechanisms. MB-COMT DNA methylation might be an independent factor contributing to the pathophysiology of CFS/FM. Further research on DNA methylation in complex conditions such as CFS/FM is warranted. We recommend future research to employ a repeated-measure design to control for biomarkers variability and within-subject changes.

Cellular reprogramming, chemoresistance, and dietary interventions in breast cancer

Breast cancer (BC) diagnosis has been associated with significant risk factors, including family history, late menopause, obesity, poor eating habits, and alcoholism. Despite the advances in the last decades regarding cancer treatment, some obstacles still hinder the effectiveness of therapy. For example, chemotherapy resistance is common in locally advanced or metastatic cancer, reducing treatment options and contributing to mortality. In this review, we provide an overview of BC metabolic changes, including the impact of restrictive diets associated with chemoresistance, the therapeutic potential of the diet on tumor progression, pathways related to metabolic health in oncology, and perspectives on the future in the area of oncological nutrition.

Androgen Plays a Potential Novel Hormonal Therapeutic Role in Th17 Cells Predominant Neutrophilic Severe Asthma by Attenuating BECs Regulated Th17 Cells Differentiation via MBD2 Expression

T helper 17 (Th17) cells subtype of non-T2 asthma is less responsive (resistant) to inhaled corticosteroids (ICS), so also called severe asthma. Methyl-CpG-binding domain protein 2 (MBD2) regulates the differentiation of the Th17 cells, showing the possibility of a therapeutic target in severe asthma. Androgen tends to show beneficial therapeutic effects and is a “hot research topic,” but its role in the differentiation and expression of Th17 cells via MBD2 is still unknown. The aim of this study was to evaluate how sex hormone interacts with MBD2 and affects the differentiation and expression of Th17 cells in severe asthma. Here, first, we measured the concentration of androgen, estrogen, and androgen estrogen ratio from subjects and correlated it with severe asthma status. Then, we established an animal model and bronchial epithelial cells (BECs) model of severe asthma to evaluate the role of MBD2 in the differentiation and expression of Th17 cells (IL-17), the therapeutic potential of sex hormones in severe asthma, and the effect of sex hormones in BECs regulated Th17 cells differentiation via MBD2 at the cellular level. Increased MBD2 expression and Th17 cells differentiation were noted in the animal and the BECs severe asthma models. Th17 cell differentiation and expression were MBD2 dependent. Androgen attenuated the differentiation of BECs regulated Th17 cells via MBD2 showing BECs as a therapeutic target of androgen, and these findings postulate the novel role of androgen in Th17 cells predominant neutrophilic severe asthma therapy through targeting MBD2.

Maternal exposure to genistein during pregnancy and oxidative DNA damage in testes of male mouse offspring

Background

Genistein is a dietary supplement with phyto-estrogenic properties. Therefore, high intake of genistein during pregnancy may have adverse effects on the genetic integrity of testes and germ cells of male offspring. In this study, we examined whether maternal exposure to genistein during pregnancy induced oxidative DNA damage in the male germline at adolescence.

Methods

Atm-ΔSRI mice have lower glucose-6-phosphate dehydrogenase (G6PDH) activity, which is important for maintaining levels of reduced glutathione and therefore these mice have an increased susceptibility to oxidative stress. Parental heterozygous Atm-ΔSRI mice received a genistein-rich or control diet, after which they were mated to obtain offspring. During pregnancy, mothers remained on the respective diets and after delivery all animals received control diets. Redox status and oxidative DNA damage were assessed in testes and sperm of 12 weeks old male offspring. Gene expression of Cyp1b1, Comt, and Nqo1 was assessed in testes, and DNA methylation as possible mechanism for transmission of effects to later life.

Results

Intake of genistein during pregnancy increased oxidative DNA damage in testes of offspring, especially in heterozygous Atm-ΔSRI mice. These increased DNA damage levels coincided with decreased expression of Comt and Nqo1. Heterozygous Atm-ΔSRI mice had higher levels of DNA strand breaks in sperm compared to wild type littermates, and DNA damage was further enhanced by a genistein-rich maternal diet. G6PDH activity was higher in mice with high maternal intake of genistein compared to control diets, suggesting compensation against oxidative stress. A positive correlation was observed between the levels of DNA methylation and oxidative DNA damage in testes.

Conclusion

These data indicate that prenatal exposure to genistein altered gene expression and increased DNA damage in testes and sperm of adolescent male offspring. These effects of genistein on DNA damage in later life coincided with alterations in DNA methylation.

The COMT Genetic Factor Regulates Chemotherapy-Related Prospective Memory Impairment in Survivors With HER2-/+ Breast Cancer

Background

Previous findings indicated that polymorphism in gene catechol-O-methyltransferase (COMT) had been linked to chemotherapy-related cognitive impairment (CRCI). Nevertheless, the motivation of COMT polymorphisms in regulating cognitive impairment in breast cancer survivors with disparate status of human epidermal growth factor receptor 2 (HER2) was still vague.

Objective

The current research aimed to evaluate the regulation of the risk by COMT genotype on CRCI in breast cancer survivors with disparate status of HER2.

Methods

Breast cancer survivors (103 with HER2− and 118 with HER2+) underwent neuropsychological tests before and after chemotherapy, containing event- and time-based prospective memory (EBPM and TBPM). Three single-nucleotide polymorphisms (SNPs) were estimated by providing peripheral blood, containing COMT (rs165599, rs737865, and rs4680).

Results

The EBPM and TBPM performances was lower as compared with these before chemotherapy (z = −7.712, z = −2.403, respectively, p < 0.01). Furthermore, the EBPM and TBPM performances of HER2− group survivors were lower than those of HER2+ group survivors after chemotherapy (z = −7.181, p < 0.01; z = −2.205 p < 0.05, respectively). The survivors with COMT (rs165599) A/A genotype carriers had a meaningfully poorer chance of memory descend [dominant model: adjusted, OR = 2.21, CI (95%) = 1.156–4.225, p = 0.016] and showed better on TBPM test, relative to G/G genotype. Patients with the COMT (rs737865) A/G and G/G genotype showed protective function than the patients with the A/A and performed better on MMSE and TBPM tests.

Conclusion

The types of HER2 may be correlated to chemotherapy-related prospective memory impairments in breast cancer survivors. Furthermore, the COMT (rs165599, rs737865) polymorphisms were correlated to the risk of TBPM decline scores and possibly be a potential genetic identifying for increasing risk of CRCI in breast cancer patients with disparate status of HER2.

Targeting of PFKFB3 with miR-206 but not mir-26b inhibits ovarian cancer cell proliferation and migration involving FAK downregulation

Few studies explored the role of microRNAs (miRNAs) in the post-transcriptional regulation of glycolytic proteins and downstream effectors in ovarian cancer cells. We recently showed that the functional activation of the cytoskeletal regulator FAK in endothelial cells is fostered by the glycolytic enhancer 6-phosphofructo-2-kinase/fructose-2,6-biphosphatase 3 (PFKFB3). We tested the hypothesis that miR-206 and mir-26b, emerging onco-suppressors targeting PFKFB3 in estrogen-dependent tumors, would regulate proliferation and migration of serous epithelial ovarian cancer (EOC) cells via common glycolytic proteins, i.e., GLUT1 and PFKFB3, and downstream FAK. PFKFB3 was overexpressed in SKOV3, and its pharmacological inhibition with 3-(3-pyridinyl)-1-(4-pyridinyl)-2-propen-1-one (3PO) significantly reduced cell proliferation and motility. Both miR-206 and miR-26b directly targeted PFKFB3 as evaluated by a luciferase reporter assay. However, endogenous levels of miR-26b were higher than those of miR-206, which was barely detectable in SKOV3 as well as OVCAR5 and CAOV3 cells. Accordingly, only the anti-miR-26b inhibitor concentration-dependently increased PFKFB3 levels. While miR-206 overexpression impaired proliferation and migration by downregulating PFKFB3 levels, the decreased PFKFB3 protein levels related to miR-26 overexpression had no functional consequences in all EOC cell lines. Finally, consistent with the migration outcome, exogenous miR-206 and miR-26b induced opposite effects on the levels of total FAK and of its phosphorylated form at Tyr576/577. 3PO did not prevent miR-26b-induced SKOV3 migration. Overall, these results support the inverse relation between endogenous miRNA levels and their tumor-suppressive effects and suggest that restoring miR-206 expression represents a potential dual anti-PFKFB3/FAK strategy to control ovarian cancer progression.

27-Hydroxycholesterol, The Estrogen Receptor Modulator, Alters DNA Methylation in Breast Cancer

27-hydroxycholesterol (27-HC) is the first known endogenous selective estrogen receptor modulator (SERM), and its elevation from normal levels is closely associated with breast cancer. A plethora of evidence suggests that aberrant epigenetic signatures in breast cancer cells can result in differential responses to various chemotherapeutics and often leads to the development of resistant cancer cells. Such aberrant epigenetic changes are mostly dictated by the microenvironment. The local concentration of oxygen and metabolites in the microenvironment of breast cancer are known to influence the development of breast cancer. Hence, we hypothesized that 27-HC, an oxysterol, which has been shown to induce breast cancer progression via estrogen receptor alpha (ERα) and liver X receptor (LXR) and by modulating immune cells, may also induce epigenetic changes. For deciphering the same, we treated the estrogen receptor-positive cells with 27-HC and identified DNA hypermethylation on a subset of genes by performing DNA bisulfite sequencing. The genes that showed significant DNA hypermethylation were phosphatidylserine synthase 2 (PTDSS2), MIR613, indoleamine 2,3-dioxygenase 1 (IDO1), thyroid hormone receptor alpha (THRA), dystrotelin (DTYN), and mesoderm induction early response 1, family member 3 (MIER). Furthermore, we found that 27-HC weakens the DNMT3B association with the ERα in MCF-7 cells. This study reports that 27-HC induces aberrant DNA methylation changes on the promoters of a subset of genes through modulation of ERα and DNMT3B complexes to induce the local DNA methylation changes, which may dictate drug responses and breast cancer development.

Girl Power in Glaucoma: The Role of Estrogen in Primary Open Angle Glaucoma

Estrogen is essential in maintaining various physiological features in women, and a decline in estrogen levels are known to give rise to numerous unfortunate symptoms associated with menopause. To alleviate these symptoms hormone replacement therapy with estrogen is often used, and has been shown to be fruitful in improving quality of life in women suffering from postmenopausal discomforts. An often forgotten condition associated with menopause is the optic nerve disorder, glaucoma. Thus, estrogen may also have an impact in maintaining the retinal ganglion cells (RGCs), which make up the optic nerve, thereby preventing glaucomatous neurodegeneration. This review aims to provide an overview of possible associations of estrogen and the glaucoma subtype, primary open-angle glaucoma (POAG), by evaluating the current literature through a PubMed-based literature search. Multiple in vitro and in vivo studies of RGC protection, as well as clinical and epidemiological data concerning the well-defined retinal neurodegenerative disorder POAG have been reviewed. Over all, deficiencies in retinal estrogen may potentially instigate RGC loss, visual disability, and eventual blindness. Estrogen replacement therapy may therefore be a beneficial future treatment. However, more studies are needed to confirm the relevance of estrogen in glaucoma prevention.

Integration of Epigenetic Mechanisms into Non-Genotoxic Carcinogenicity Hazard Assessment: Focus on DNA Methylation and Histone Modifications

Epigenetics involves a series of mechanisms that entail histone and DNA covalent modifications and non-coding RNAs, and that collectively contribute to programing cell functions and differentiation. Epigenetic anomalies and DNA mutations are co-drivers of cellular dysfunctions, including carcinogenesis. Alterations of the epigenetic system occur in cancers whether the initial carcinogenic events are from genotoxic (GTxC) or non-genotoxic (NGTxC) carcinogens. NGTxC are not inherently DNA reactive, they do not have a unifying mode of action and as yet there are no regulatory test guidelines addressing mechanisms of NGTxC. To fil this gap, the Test Guideline Programme of the Organisation for Economic Cooperation and Development is developing a framework for an integrated approach for the testing and assessment (IATA) of NGTxC and is considering assays that address key events of cancer hallmarks. Here, with the intent of better understanding the applicability of epigenetic assays in chemical carcinogenicity assessment, we focus on DNA methylation and histone modifications and review: (1) epigenetic mechanisms contributing to carcinogenesis, (2) epigenetic mechanisms altered following exposure to arsenic, nickel, or phenobarbital in order to identify common carcinogen-specific mechanisms, (3) characteristics of a series of epigenetic assay types, and (4) epigenetic assay validation needs in the context of chemical hazard assessment. As a key component of numerous NGTxC mechanisms of action, epigenetic assays included in IATA assay combinations can contribute to improved chemical carcinogen identification for the better protection of public health.

Ten Years of EWAS

Epigenome-wide association study (EWAS) has been applied to analyze DNA methylation variation in complex diseases for a decade, and epigenome as a research target has gradually become a hot topic of current studies. The DNA methylation microarrays, next-generation, and third-generation sequencing technologies have prepared a high-quality platform for EWAS. Here, the progress of EWAS research is reviewed, its contributions to clinical applications, and mainly describe the achievements of four typical diseases. Finally, the challenges encountered by EWAS and make bold predictions for its future development are presented.

Food frequency questionnaire is a valid assessment tool of quercetin and kaempferol intake in Iranian breast cancer patients according to plasma biomarkers

In epidemiological and clinical studies, the most common nutritional tool to assess dietary flavonol intake is the food frequency questionnaire (FFQ), which needs to contain a detailed list of plant-based foods and be previously validated. Our study aimed to assess the accuracy of dietary flavonol (quercetin, kaempferol, and isorhamnetin) intake from a food frequency questionnaire (FFQ) compared to fasting plasma flavonol concentrations, as biomarkers of exposure, in breast cancer patients. In a consecutive case series, newly diagnosed patients with breast cancer (n = 140) were recruited at Nour-Nejat Hospital, Tabriz, Iran. Flavonol intake was assessed using a validated FFQ. Plasma flavonol concentrations were measured using high-performance liquid chromatography-ultraviolet detection. The accuracy of dietary status was evaluated using a receiver operating characteristic (ROC) and area under the ROC curve (AUC). Dietary status was shown in dichotomous using ROC-cutoff point. The plasma concentrations of quercetin were moderately correlated with dietary intake of quercetin (Spearman's correlation coefficient (r_s) = 0.188, P < .05; r_partial= 0.330, P < .01) and plasma concentrations of isorhamnetin (r_s = 0.337, P < .001). A linear correlation between dietary levels and plasma concentrations of kaempferol was attained (r_partial = 0.240, P < .05). Using a ROC-cutoff of 61.9 nmol/L for plasma quercetin (test reference), we were able to differentiate between lower and higher consumers of quercetin with an AUC_{ROC-based reference} =0.65 (P < .01, sensitivity = 61.8%, and specificity = 60.0%). Using a plasma kaempferol concentration of 60.1 nmol/L (ROC-cutoff), it was possible to detect significant differences between higher and lower intakes of kaempferol (AUC_{ROC-based reference} = 0.64, P < .05). The correlations and diagnostic performance with plasma concentrations could present a significant accuracy rate (validity), which seems acceptable for a nutritional questionnaire (FFQ) to assess intakes intake levels of quercetin and kaempferol. An improvement in the accuracy of the flavonol exposure can provide more precise relationship with health outcomes, which may increase their clinical significance.

Computational analysis of deleterious single nucleotide polymorphisms in catechol O-Methyltransferase conferring risk to post-traumatic stress disorder

Post-traumatic stress disorder (PTSD) is one of the prevalent neurological disorder which is drawing increased attention over the past few decades. Major risk factors for PTSD can be categorized into environmental and genetic factors. Among the genetic risk factors, polymorphisms in the catechol-O-methyltransferase (COMT) gene is known to be associated with the risk for PTSD. In the present study, we analysed the impact of deleterious single nucleotide polymorphisms (SNPs) in the COMT gene conferring risk to PTSD using computational based approaches followed by molecular dynamic simulations. The data on COMT gene associated with PTSD were collected from several databases including Online Mendelian Inheritance in Man (OMIM) search. Datasets related to SNP were downloaded from the dbSNP database. To study the structural and dynamic effects of COMT wild type and mutant forms, we performed molecular dynamics simulations (MD simulations) at a time scale of 300 ns. Results from screening the SNPs using the computational tools SIFT and Polyphen-2 demonstrated that the SNP rs4680 (V158M) in COMT has a deleterious effect with phenotype in PTSD. Results from the MD simulations showed that there is some major fluctuations in the structural features including root mean square deviation (RMSD), radius of gyration (Rg), root mean square fluctuation (RMSF) and secondary structural elements including α-helices, sheets and turns between wild-type (WT) and mutant forms of COMT protein. In conclusion, our study provides novel insights into the deleterious effects and impact of V158M mutation on COMT protein structure which plays a key role in PTSD.

Comprehensive analysis of regulation of DNA methyltransferase isoforms in human breast tumors

Significant reprogramming of epigenome is widely described during pathogenesis of breast cancer. Transformation of normal cell to hyperplastic cell and to neoplastic phenotype is associated with aberrant DNA (de)methylation, which, through promoter and enhancer methylation changes, activates oncogenes and silence tumor suppressor genes in variety of tumors including breast. DNA methylation, one of the major epigenetic mechanisms is catalyzed by evolutionarily conserved isoforms namely, DNMT1, DNMT3A and DNMT3B in humans. Over the years, studies have demonstrated intricate and complex regulation of DNMT isoforms at transcriptional, translational and post-translational levels. The recent findings of allosteric regulation of DNMT isoforms and regulation by other interacting chromatin modifying proteins emphasizes functional integrity and their contribution for the development of breast cancer and progression. DNMT isoforms are regulated by several intrinsic and extrinsic parameters. In the present review, we have extensively performed bioinformatics analysis of expression of DNMT isoforms along with their transcriptional and post-transcriptional regulators such as transcription factors, interacting proteins, hormones, cytokines and dietary elements along with their significance during pathogenesis of breast tumors. Our review manuscript provides a comprehensive understanding of key factors regulating DNMT isoforms in breast tumor pathology and documents unsolved issues.

A Tale of Ice and Fire: The Dual Role for 17β-Estradiol in Balancing DNA Damage and Genome Integrity

17β-estradiol (E2) regulates human physiology both in females and in males. At the same time, E2 acts as a genotoxic substance as it could induce DNA damages, causing the initiation of cellular transformation. Indeed, increased E2 plasma levels are a risk factor for the development of several types of cancers including breast cancer. This paradoxical identity of E2 undermines the foundations of the physiological definition of "hormone" as E2 works both as a homeostatic regulator of body functions and as a genotoxic compound. Here, (i) the molecular circuitries underlying this double face of E2 are reviewed, and (ii) a possible framework to reconcile the intrinsic discrepancies of the E2 function is reported. Indeed, E2 is a regulator of the DNA damage response, which this hormone exploits to calibrate its genotoxicity with its physiological effects. Accordingly, the genes required to maintain genome integrity belong to the E2-controlled cellular signaling network and are essential for the appearance of the E2-induced cellular effects. This concept requires an "upgrade" to the vision of E2 as a "genotoxic hormone", which balances physiological and detrimental pathways to guarantee human body homeostasis. Deregulation of this equilibrium between cellular pathways would determine the E2 pathological effects.

Double dissociation of inhibitory effects between the hippocampal TET1 and TET3 in the acquisition of morphine self-administration in rats

The development of opioid addiction involves DNA methylation. Accordingly, the DNA demethylation, induced by ten-eleven translocation (Tet) enzymes, may represent a novel approach to prevent opioid addiction. The present study examined the role of TET1 and TET3 in the development of morphine-seeking behavior in rats. We showed that 1 day of morphine self-administration (SA) training upregulated TET3 but not TET1 expression in the hippocampal CA1. With 7 days of morphine SA training, the expression of TET3 in the CA1 returned to the baseline level, while the TET1 expression was downregulated. No change of TET1 and TET3 in the nucleus accumbens shell was observed in morphine SA trained rats, or in the yoked morphine rats, or in rats trained for saccharin SA. Furthermore, we found that knocking down TET3 expression in the CA1 accelerated the acquisition of morphine SA, while overexpression of the catalytic domain of TET1 in the CA1 attenuated the acquisition. Together, these findings suggest that TET1 and TET3 in the CA1 are important epigenetic modulators involved in the morphine-seeking behavior and provide a new strategy in the treatment of opioid addiction.

An identified PfHMGB1 promotes microcystin-LR-induced liver injury of yellow catfish (Pelteobagrus fulvidraco)

Microcystin-LR (MC-LR) is a potent hepatotoxin that can cause liver inflammation and injury. However, the mode of action of related inflammatory factors is not fully understood. PfHMGB1 is an inflammatory factor induced at the mRNA level in the liver of juvenile yellow catfish (Pelteobagrus fulvidraco) that were intraperitoneally injected with 50 μg/kg MC-LR. The PfHMGB1 mRNA level was highest in the liver and muscle among 11 tissues examined. The full-length cDNA sequence of PfHMGB1 was cloned and overexpressed in E. coli, and the purified protein rPfHMGB1 demonstrated DNA binding affinity. Endotoxin-free rPfHMGB1 (6-150 μg/mL) also showed dose-dependent hepatotoxicity and induced inflammatory gene expression of primary hepatocytes. PfHMGB1 antibody (anti-PfHMGB1) in vitro reduced MC-LR (30 and 50 μmol/L)-induced hepatotoxicity, suggesting PfHMGB1 is important in the toxic effects of MC-LR. In vivo study showed that MC-LR upregulated PfHMGB1 protein in the liver. The anti-PfHMGB1 blocked its counterpart and reduced ALT/AST activities after MC-LR exposure. Anti-PfHMGB1 partly neutralized MC-LR-induced hepatocyte disorganization, nucleus shrinkage, mitochondria, and rough endoplasmic reticula destruction. These findings suggest that PfHMGB1 promotes MC-LR-induced liver damage in the yellow catfish. HMGB1 may help protect catfish against widespread microcystin pollution.

Tamoxifen induces stem-like phenotypes and multidrug resistance by altering epigenetic regulators in ERα+ breast cancer cells

BACKGROUND

To understand the mechanism underlying tamoxifen-induced multidrug resistance (MDR) and stem-like phenotypes in breast cancer cells, we treated the MCF-7 cells with 4-hydroxy-tamoxifen (TAM) for 6 months continuously and established MCF-7 tamoxifen resistance (TR) phenotypes.

METHODS

In the present study, the following methods were used: cell viability assay, colony formation, cell cycle analysis, ALDEFLUOR assay, mammosphere formation assay, chromatin immunoprecipitation (ChIP) assay, PCR array, western blot analysis and quantitative reverse transcription polymerase chain reaction (QRT-PCR).

RESULTS

The expression of ERα was significantly higher in MCF7-TR cells when compared with parental MCF-7 cells. MCF7-TR cells exposed to TAM showed a significant increase in the proliferation and rate of colony formation. The number of cancer stem cells was higher in MCF7-TR cells as observed by the increase in the number of ALDH+ cells. Furthermore, the number of mammospheres formed from the FACS-sorted ALDH+ cells was higher in MCF7-TR cells. Using PCR array analysis, we were able to identify that the long-term exposure of TAM leads to alterations in the epigenetic and MDR stem cell marker genes. Furthermore, western blot analysis demonstrated elevated levels of Notch-1 expression in MCF-TR cells compared with MCF-7 cells. Chromatin immunoprecipitation (ChIP) assay revealed that Notch-1 enhanced the cyclin D1 expression significantly in these cells. In addition, we observed that MCF7-TR cells were resistant to doxorubicin but not the MCF-7 cells.

CONCLUSIONS

In the present study, we conclude that the treatment with tamoxifen induces multiple epigenetic alterations that lead to the development of MDR and stem-like phenotypes in breast cancers. Therefore, our study provides better insights to develop novel treatment regime to control the progression of breast cancer.

Effects of caffeic acid on epigenetics in the brain of rats with chronic unpredictable mild stress

The present study hypothesized that caffeic acid (3,4-dihydroxycinnamic acid; CaA) may exert antidepressant-like effects in rats with chronic unpredictable mild stress via epigenetic mechanisms, such as DNA methylation and hydroxymethylation. The chronic unpredictable mild stress (CUMS) model was used to analyze the effects of CaA on behavioral phenotypes, and to evaluate the distribution of 5-methylcytosine (5mC) and 5-hydroxymethylcytosine (5hmC) in the hippocampus and prefrontal cortex using immunohistochemistry and immunofluorescence. mRNA levels of the genes encoding brain-derived neurotropic factor (BDNF) and catechol-O-methyltransferase (COMT), and key enzymes regulating DNA methylation [DNA methyltransferase (DNMT)1 and DNMT3A] and hydroxymethylation [Ten-eleven translocation (TET)1-3] were examined using quantitative (q)PCR. Furthermore, enrichment of 5mC and 5hmC at the promotor regions of the Bdnf and Comt genes was quantified using chromatin immunoprecipitation-qPCR. Behavioral data showed that CaA exerted a slight antidepressant-like effect. Bdnf and Comt genes showed differential expression patterns due to CUMS. CaA intervention induced different Dnmt1/Dnmt3a and Tet1/Tet2 mRNA levels in the hippocampus and prefrontal cortex, respectively. CaA regulated the ratio of 5mC/5hmC at the promotor region of the Bdnf and Comt genes and therefore influenced gene expression, which may be a valuable therapeutic option for major depressive disorder (MDD). In conclusion, there were epigenetic changes in the hippocampus and prefrontal cortex in CUMS rats, and CaA may function as a modulator of DNA methylation to regulate gene transcription, thus providing a mechanistic basis for the use of this phytochemical agent in the treatment of MDD.

The Impact of Natural Dietary Compounds and Food-Borne Mycotoxins on DNA Methylation and Cancer

Cancer initiation and progression is an accumulation of genetic and epigenetic modifications. DNA methylation is a common epigenetic modification that regulates gene expression, and aberrant DNA methylation patterns are considered a hallmark of cancer. The human diet is a source of micronutrients, bioactive molecules, and mycotoxins that have the ability to alter DNA methylation patterns and are thus a contributing factor for both the prevention and onset of cancer. Micronutrients such as betaine, choline, folate, and methionine serve as cofactors or methyl donors for one-carbon metabolism and other DNA methylation reactions. Dietary bioactive compounds such as curcumin, epigallocatechin-3-gallate, genistein, quercetin, resveratrol, and sulforaphane reactivate essential tumor suppressor genes by reversing aberrant DNA methylation patterns, and therefore, they have shown potential against various cancers. In contrast, fungi-contaminated agricultural foods are a source of potent mycotoxins that induce carcinogenesis. In this review, we summarize the existing literature on dietary micronutrients, bioactive compounds, and food-borne mycotoxins that affect DNA methylation patterns and identify their potential in the onset and treatment of cancer.

Estrogen receptor α is involved in the regulation of ITGA8 methylation in estrogen receptor-positive breast cancer

Background

Integrin subunit α 8 (ITGA8) methylation has been associated with the development of several cancers, but its contribution to breast cancer remains unclear. The present study aimed to investigate the methylation status of ITGA8, and the underlying regulatory mechanisms of ITGA8 methylation in breast cancer.

Methods

ITGA8 expression was investigated using the Gene Expression Profiling Interactive Analysis 2 (GEPIA2) database and the Breast Cancer Gene-Expression Miner v.4.4 (bc-GenExMiner v4.4). The association between ITGA8 expression levels and the survival rate of breast cancer patients was evaluated using The Cancer Genome Atlas (TCGA) database and Gene Expression-based Outcome for Breast Cancer Online (GOBO): Gene Set Analysis. Methylation-specific PCR (MSP) was used to detect the methylation of ITGA8. Protein level of ITGA8 was determined by Western blot analysis.

Results

ITGA8 was expressed at low levels in human breast cancer cells compared to non-tumorigenic breast cells and breast tissue, and was upregulated in estrogen receptor (ER)-positive tissue compared with ER-negative tissue (P<0.01). ITGA8 gene expression was negatively associated with breast tumor stage and survival rate in all breast cancer patients. However, ER-positive patients with low ITGA8 expression showed poorer distant metastasis-free survival (DMFS) and recurrence-free survival (RFS) rates than patients with high ITGA8 expression. This was not observed in the ER-negative population. Mechanistically speaking, hypermethylation of ITGA8 was discovered in ER-positive breast cancer cells. Administration of the methylation inhibitor, 5-aza-2’-deoxycytidine (5-aza-dC), significantly elevated protein expression of ITGA8 in ER-positive breast cancer cells compared to ER-negative cells. The positive association between ITGA8 status and methylation was also observed in clinical tissue specimens. When treated with 17-beta-estradiol, an antagonist of ERα, 5-aza-dC-induced upregulation of ITGA8 in ER-positive breast cancer cells was no longer observed.

Conclusions

Low ITGA8 expression in ER-positive breast cancer might be caused by the hypermethylation of ITGA8, a process dependent on ERα. Our findings provide an important foundation for investigations into ITGA8-targeted treatment strategies for ER-positive breast cancer.

Sex hormones and genetic variants in hormone metabolic pathways associated with the risk of colorectal cancer

OBJECTIVE

The different incidence of colorectal cancer between the sexes suggests that sex hormones may be involved in the susceptibility to colorectal cancer. The association between sex hormones and genetic variants in hormone metabolic pathways and the colorectal cancer risk remains unclear.

METHODS

We detected sex hormone levels in plasma from colorectal cancer patients and controls in males by ultra-high-performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS). We evaluated the clinical significance of sex hormones on colorectal cancer diagnosis with the area under the receiver operating characteristic curve (AUC). The role of genetic variants in hormone metabolic pathways in the colorectal cancer risk was assessed by a logistic regression model. The biological functions were detected by luciferase reporter assays and cell behavior experiments.

RESULTS

We found that 2-methoxyestrone (2-MeO-E1) was highly expressed in cases (P_FDR = 3.48 × 10^-19). The expression of 2-MeO-E1 in plasma showed improved accuracy for predicting colorectal cancer (AUC = 0.88). In the 2-MeO-E1 metabolic pathway, rs165599 in COMT was significantly associated with an increased risk of colorectal cancer (P = 0.009). Mechanistically, we found that the rs165599 G allele could decrease the binding ability of miR-22-3p to the COMT 3'-UTR. Furthermore, knockdown of COMT inhibited cell proliferation, induced cell apoptosis and arrested the cell cycle in the G1 phase.

CONCLUSION

This is the first study to show that 2-MeO-E1 and a genetic variant in COMT contribute to the susceptibility to colorectal cancer. These results shed light on the different incidence of colorectal cancer between the sexes.

Estradiol promotes the progression of ER+ breast cancer through methylation-mediated RSK4 inactivation

Background: It’s well documented that estrogen plays a vital role in breast cancer progression, but the molecular mechanisms underlying it still remains incompletely clear. This study aimed to explore whether ribosomal protein S6 kinase 4 (RSK4) was involved in estrogen-induced breast cancer development and its underlying mechanism.

Methods: The expressions of estrogen receptor (ER) and RSK4 were assessed by immunohistochemistry, RT-PCR and Western blotting. The methylation of RSK4 promoter was evaluated by bisulfite genomic sequencing. MTT, clone formation, flow cytometry and Transwell chamber assays were performed to detect cell proliferation, clone formation, apoptosis and invasion abilities. Luciferase gene reporter assay was used to detect the transcriptional activity of RSK4. The expressions of methyltransferases, such as DNMT1, DNMT3A and DNMT3B were tested by Western blotting.

Results: ER expression and RSK4 methylation were significantly elevated in ER positive (ER+) breast cancer tissues and MCF-7 cells, whereas RSK4 expression was reduced. 17β-estradiol (E2) treatment obviously decreased RSK4 expression and transcriptional activity, as well as promoted cell proliferation, clone formation and invasion and reduced cell apoptosis in ER+ MCF-7 cells. Furthermore, E2 reduced RSK4 expression through promoting DNMT3B-induced RSK4 methylation.

Conclusion:  In summary, the present study reveals that estrogen promotes the progression of breast cancer through methylation-mediated RSK4 inactivation in ER+ breast cancer. Our study might provide a novel target for the treatment of ER+ breast cancer.