Resolvin D2 supports MCF-7 cell proliferation via activation of estrogen receptor

Post-Transcriptional and Epigenetic Regulation of Estrogen Signaling

Post-translational and epigenetic regulation are important mechanisms controlling functions of genes and proteins. Although the "classic" estrogen receptors (ERs) have been acknowledged to function in mediating estrogen effects via transcriptional mechanisms, estrogenic agents modulate the turnover of several proteins via post-transcriptional and post-translational pathways including epigenetics. For instance, the metabolic and angiogenic action of G-protein coupled estrogen receptor (GPER) in vascular endothelial cells has been recently elucidated. By interacting with GPER, 17β-estradiol and the GPER agonist G1 enhance endothelial stability of 6-phosphofructo-2-kinase/fructose-2,6-biphosphatase 3 (PFKFB3) and capillary tube formation by increasing ubiquitin-specific peptidase 19 levels, thereby reducing PFKFB3 ubiquitination and proteasomal degradation. In addition to ligands, the functional expression and trafficking of ERs can be modulated by post-translational modification, including palmitoylation. MicroRNAs (miRNAs), the most abundant form of endogenous small RNAs in humans, regulate multiple target genes and are at the center of the multi-target regulatory network. This review also discusses the emerging evidence of how miRNAs affect glycolytic metabolism in cancer, as well as their regulation by estrogens. Restoring dysregulated miRNA expression represents a promising strategy to counteract the progression of cancer and other disease conditions. Accordingly, estrogen post-transcriptional regulatory and epigenetic mechanisms represent novel targets for pharmacological and nonpharmacological intervention for the treatment and prevention of hormone-sensitive noncommunicable diseases, including estrogen-sensitive cancers of the reproductive system in women. SIGNIFICANCE STATEMENT: The effects of estrogen are mediated by several mechanisms that are not limited to the transcriptional regulation of target genes. Slowing down the turnover of master regulators of metabolism by estrogens allows cells to rapidly adapt to environmental cues. Identification of estrogen-targeted microRNAs may lead to the development of novel RNA therapeutics that disrupt pathological angiogenesis in estrogen-dependent cancers.

Glucocorticoid resistance of migration and gene expression in a daughter MDA-MB-231 breast tumour cell line selected for high metastatic potential

Glucocorticoids are commonly used to prevent chemotherapy-induced nausea and vomiting despite a lack of understanding of their direct effect on cancer progression. Recent studies suggest that glucocorticoids inhibit cancer cell migration. However, this action has not been investigated in estrogen receptor (ER)-negative breast tumour cells, although activation of the glucocorticoid receptor (GR) is associated with a worse prognosis in ER-negative breast cancers. In this study we have explored the effect of glucocorticoids on the migration of the ER-negative MDA-MB-231 human breast tumour cell line and the highly metastatic MDA-MB-231-HM.LNm5 cell line that was generated through in vivo cycling. We show for the first time that glucocorticoids inhibit 2- and 3-dimensional migration of MDA-MB-231 cells. Selection of cells for high metastatic potential resulted in a less migratory cell phenotype that was resistant to regulation by glucocorticoids and showed decreased GR receptor expression. The emergence of glucocorticoid resistance during metastatic selection may partly explain the apparent disparity between the clinical and in vitro evidence regarding the actions of glucocorticoids in cancer. These findings highlight the highly plastic nature of tumour cells, and underscore the need to more fully understand the direct effect of glucocorticoid treatment on different stages of metastatic progression.

Inflammation: maladies, models, mechanisms and molecules

The continued focus of attention on the diversity of mechanisms underpinning inflammation has improved our understanding of the potential to target specific pathways in the inflammatory network to achieve meaningful therapeutic gains. In this themed issue of the British Journal of Pharmacology our scope was deliberately broad, ranging across both acute and chronic disease in various organs. Pro- and anti-inflammatory mechanisms receive attention as does the phenotype of macrophages. Whilst the manifestations of neuro-inflammation are less obvious than those in peripheral tissues, central innate and adaptive immunity in brain and the M1/M2 phenotypes of microglia are topics of special interest. The contributions to the inflammatory milieu of cytokines, chemokines and associated signalling cascades are considered. Overall, the coverage herein advances the basic science underpinning our understanding of inflammation and emphasizes its importance in different pathologies.

Pro-Resolving Effects of Resolvin D2 in LTD4 and TNF-α Pre-Treated Human Bronchi

Inflammation is a major burden in respiratory diseases, resulting in airway hyperresponsiveness. Our hypothesis is that resolution of inflammation may represent a long-term solution in preventing human bronchial dysfunctions. The aim of the present study was to assess the anti-inflammatory effects of RvD₂, a member of the D-series resolving family, with concomitant effects on ASM mechanical reactivity. The role and mode of action of RvD₂ were assessed in an in vitro model of human bronchi under pro-inflammatory conditions, induced either by 1 μM LTD₄ or 10 ng/ml TNF-α pre-treatment for 48h. TNF-α and LTD₄ both induced hyperreactivity in response to pharmacological stimuli. Enhanced 5-Lipoxygenase (5-LOX) and cysteinyl leukotriene receptor 1 (CysLTR1) detection was documented in LTD₄ or TNF-α pre-treated human bronchi when compared to control (untreated) human bronchi. In contrast, RvD₂ treatments reversed 5-LOX/β-actin and CysLTR1/β-actin ratios and decreased the phosphorylation levels of AP-1 subunits (c-Fos, c-Jun) and p38-MAP kinase, while increasing the detection of the ALX/FPR2 receptor. Moreover, various pharmacological agents revealed the blunting effects of RvD₂ on LTD₄ or TNF-α induced hyper-responsiveness. Combined treatment with 300 nM RvD₂ and 1 μM WRW4 (an ALX/FPR2 receptor inhibitor) blunted the pro-resolving and broncho-modulatory effects of RvD₂. The present data provide new evidence regarding the role of RvD₂ in a human model of airway inflammation and hyperrresponsiveness.

Aspirin-triggered resolvin D1 inhibits TGF-β1-induced EMT through the inhibition of the mTOR pathway by reducing the expression of PKM2 and is closely linked to oxidative stress

Transforming growth factor-β1 (TGF-β1) is a potent stimulator of the epithelial-to-mesenchymal transition (EMT), which is a key event in the initiation of tumor cell metastasis. Aspirin-triggered resolvin D1 (AT-RvD1) is known to be involved in the resolution of inflammation; however, whether AT-RvD1 exerts effects on TGF-β1-induced EMT remains unclear. Thus, we first explored the effects of AT-RvD1 on the EMT of lung cancer cells. Treatment with TGF-β1 increased the level of reactive oxygen species (ROS) and reduced the expression of nuclear factor (erythroid-derived 2)-like 2 (Nrf2). The expression of E-cadherin in A549 lung cancer cells was reduced, and the expression of vimentin was enhanced. AT-RvD1 enhanced the expression of E-cadherin in a concentration‑dependent manner and suppressed the expression of Nrf2 and vimentin. AT-RvD1 did not affect the proliferation of A549 lung cancer cells whereas it suppressed the TGF-β1‑induced migration and invasion of A549 cells. The expression of pyruvate kinase M2 (Pkm2), which is associated with TGF-β-induced factor homeobox 2 (TGIF2), was significantly increased during the TGF-β1-induced EMT of A549 lung cancer cells. The mTOR pathway is known to regulate the expression of various glycolytic enzymes including Pkm2. We examined the involvement of the mTOR pathway in the suppressive effects of AT-RvD1 on Pkm2 expression in A549 cells. The mTOR activator restored the expression of Pkm2 and partially downregulated the expression of E-cadherin. However, the mTOR activator had no clear effect on the TGF-β1-induced EMT. These results suggest that AT-RvD1 is closely linked to oxidative stress and partially inhibits TGF-β1-induced EMT through the inhibition of the mTOR pathway by reducing the expression of Pkm2.

Electrochemical estrogen screen method based on the electrochemical behavior of MCF-7 cells

It was an urgent task to develop quick, cheap and accurate estrogen screen method for evaluating the estrogen effect of the booming chemicals. In this study, the voltammetric behavior between the estrogen-free and normal fragmented MCF-7 cell suspensions were compared, and the electrochemical signal (about 0.68V attributed by xanthine and guanine) of the estrogen-free fragmented MCF-7 cell suspension was obviously lower than that of the normal one. The electrochemistry detection of ex-secretion purines showed that the ability of ex-secretion purines of cells sharp decreased due to the removing of endogenous estrogen. The results indicated that the electrochemical signal of MCF-7 cells was related to the level of intracellular estrogen. When the level of intracellular estrogen was down-regulated, the concentrations of the xanthine and hypoxanthine decreased, which led to the electrochemical signal of MCF-7 cells fall. Based on the electrochemical signal, the electrochemical estrogen screen method was established. The estrogen effect of estradiol, nonylphenol and bisphenol A was evaluated with the electrochemical method, and the result was accordant with that of MTT assay. The electrochemical estrogen screen method was simple, quickly, cheap, objective, and it exploits a new way for the evaluation of estrogenic effects of chemicals.

Eicosopentaneoic Acid and Other Free Fatty Acid Receptor Agonists Inhibit Lysophosphatidic Acid- and Epidermal Growth Factor-Induced Proliferation of Human Breast Cancer Cells

Many key actions of ω-3 (n-3) fatty acids have recently been shown to be mediated by two G protein-coupled receptors (GPCRs) in the free fatty acid receptor (FFAR) family, FFA1 (GPR40) and FFA4 (GPR120). n-3 Fatty acids inhibit proliferation of human breast cancer cells in culture and in animals. In the current study, the roles of FFA1 and FFA4 were investigated. In addition, the role of cross-talk between GPCRs activated by lysophosphatidic acid (LPA), and the tyrosine kinase receptor activated by epidermal growth factor (EGF), was examined. In MCF-7 and MDA-MB-231 human breast cancer cell lines, both LPA and EGF stimulated proliferation, Erk activation, Akt activation, and CCN1 induction. LPA antagonists blocked effects of LPA and EGF on proliferation in MCF-7 and MDA-MB-231, and on cell migration in MCF-7. The n-3 fatty acid eicosopentaneoic acid inhibited LPA- and EGF-induced proliferation in both cell lines. Two synthetic FFAR agonists, GW9508 and TUG-891, likewise inhibited LPA- and EGF-induced proliferation. The data suggest a major role for FFA1, which was expressed by both cell lines. The results indicate that n-3 fatty acids inhibit breast cancer cell proliferation via FFARs, and suggest a mechanism involving negative cross-talk between FFARS, LPA receptors, and EGF receptor.

Activation and resolution of periodontal inflammation and its systemic impact

Inflammation is a highly organized event impacting upon organs, tissues and biological systems. Periodontal diseases are characterized by dysregulation or dysfunction of resolution pathways of inflammation that results in failure to heal and in a dominant chronic, progressive, destructive and predominantly unresolved inflammation. The biological consequences of inflammatory processes may be independent of the etiological agents, such as trauma, microbial organisms and stress. The impact of the inflammatory pathological process depends upon the tissues or organ system affected. Whilst mediators are similar, there is tissue specificity for the inflammatory events. It is plausible that inflammatory processes in one organ could directly lead to pathologies in another organ or tissue. Communication between distant parts of the body and their inflammatory status is also mediated by common signaling mechanisms mediated via cells and soluble mediators. This review focuses on periodontal inflammation, its systemic associations and advances in therapeutic approaches based on mediators acting through orchestration of natural pathways to resolution of inflammation. We also discuss a new treatment concept in which natural pathways of resolution of periodontal inflammation can be used to limit systemic inflammation and promote healing and regeneration.

Glutamic acid ameliorates estrogen deficiency-induced menopausal-like symptoms in ovariectomized mice

Some amino acids are considered alternative therapies for improving menopausal symptoms. Glutamic acid (GA), which is abundant in meats, fish, and protein-rich plant foods, is known to be a neurotransmitter or precursor of γ-aminobutyric acid. Although it is unclear if GA functions in menopausal symptoms, we hypothesized that GA would attenuate estrogen deficiency-induced menopausal symptoms. The objective to test our hypothesis was to examine an estrogenic effect of GA in ovariectomized (OVX) mice, estrogen receptor (ER)-positive human osteoblast-like MG-63 cells, and ER-positive human breast cancer MCF-7 cells. The results demonstrated that administration with GA to mice suppressed body weight gain and vaginal atrophy when compared with the OVX mice. A microcomputed tomographic analysis of the trabecular bone showed increases in bone mineral density, trabecular number, and connectivity density as well as a significant decrease in total porosity of the OVX mice treated with GA. In addition, GA increased serum levels of alkaline phosphatase and estrogen compared with the OVX mice. Furthermore, GA induced proliferation and increased ER-β messenger RNA (mRNA) expression, estrogen response element (ERE) activity, extracellular signal-regulated kinase phosphorylation, and alkaline phosphatase activity in MG-63 cells. In MCF-7 cells, GA also increased proliferation, Ki-67 mRNA expression, ER-β mRNA expression, and ERE activity. Estrogen response element activity increased by GA was inhibited by an estrogen antagonist. Taken together, our data demonstrated that GA has estrogenic and osteogenic activities in OVX mice, MG-63 cells, and MCF-7 cells.