Knockdown of receptor for advanced glycation end products attenuate 17α-ethinyl-estradiol dependent proliferation and survival of MCF-7 breast cancer cells

Hormone effects of eighteen bisphenol analogues and their effects on cellular homeostasis and the typical signal pathways

Through the transfer chain of surroundings from feed to the farmed-animals and ultimately the corresponding livestock and poultry products, people are exposed to large amounts of bisphenol analogues (BPs), such as rational emissions from manufacturing plants, feed packaging bags and food packaging contact. Some BPs have been reported to show certain toxicological effects, especially, estrogen and endocrine disrupting effect. With the increasing application of BPs, the problem is becoming more and more serious. We systematically studied the hormonal effects of 18 BPs and their effects on cell homeostasis and classical signaling pathways by using classical E-SCREEN assay, fluorescent probes and western blotting. The results confirmed the estrogen-like effect of 13 BPs and 6 BPs obtained high docking scores (Scores < -9.0) for the three receptors simultaneously with the main interactions of hydrophobic, hydrogen and π-stacking of T-type bonds. BPAP regulates cells via apoptosis and steroid signaling pathway by intracellular ROS and mitochondrial followed the caspase pathway. BPE and BPS were involved in the classical NF-κB and Hippo signaling pathways. All data provides scientific basis for the safety risk assessment of endocrine disrupting and cellular homeostasis evaluation of BPs as chronic environmental pollution.

Benzotriazole Ultraviolet Stabilizers Promote Breast Cancer Cell Proliferation via Activating Estrogen-Related Receptors α and γ at Human-Relevant Levels

Benzotriazole ultraviolet stabilizers (BUVSs) are ubiquitous emerging pollutants that have been reported to show estrogenic disruption effects through interaction with the classic estrogen receptors (ERs) in the fashion of low activity. The present study aims at revealing the potential disruption mechanism via estrogen-related receptors α and γ (ERRα and ERRγ) pathways. By the competitive binding assay, we first found that BUVSs bond to ERRγ ligand binding domain (ERRγ-LBD) with Kd ranging from 0.66 to 19.27 μM. According to the results of reporter gene assays, the transcriptional activities of ERRα and ERRγ were promoted by most tested BUVSs with the lowest observed effective concentrations (LOEC) from 10 to 100 nM, which are in the range of human exposure levels. At 1 μM, most tested BUVSs showed higher agonistic activity toward ERRγ than ERRα. The most effective two BUVSs promoted the MCF-7 proliferation dependent on ERRα and ERRγ with a LOEC of 100 nM. The molecular dynamics simulation showed that most studied BUVSs had lower binding free energy with ERRγ than with ERRα. The structure-activity relationship analysis revealed that molecular polarizability, electron-donating ability, ionization potential, and softness were the main structural factors impacting the binding of BUVSs with ERRγ. Overall, our results provide novel insights into the estrogenic disruption effects of BUVSs.

Targeting Estrogens and Various Estrogen-Related Receptors against Non-Small Cell Lung Cancers: A Perspective

Non-small cell lung cancers (NSCLCs) account for ~85% of lung cancer cases worldwide. Mammalian lungs are exposed to both endogenous and exogenous estrogens. The expression of estrogen receptors (ERs) in lung cancer cells has evoked the necessity to evaluate the role of estrogens in the disease progression. Estrogens, specifically 17β-estradiol, promote maturation of several tissue types including lungs. Recent epidemiologic data indicate that women have a higher risk of lung adenocarcinoma, a type of NSCLC, when compared to men, independent of smoking status. Besides ERs, pulmonary tissues both in healthy physiology and in NSCLCs also express G-protein-coupled ERs (GPERs), epidermal growth factor receptor (EGFRs), estrogen-related receptors (ERRs) and orphan nuclear receptors. Premenopausal females between the ages of 15 and 50 years synthesize a large contingent of estrogens and are at a greater risk of developing NSCLCs. Estrogen-ER/GPER/EGFR/ERR-mediated activation of various cell signaling molecules regulates NSCLC cell proliferation, survival and apoptosis. This article sheds light on the most recent achievements in the elucidation of sequential biochemical events in estrogen-activated cell signaling pathways involved in NSCLC severity with insight into the mechanism of regulation by ERs/GPERs/EGFRs/ERRs. It further discusses the success of anti-estrogen therapies against NSCLCs.

Insight into the mechanism of tetrachlorobisphenol A (TCBPA)-induced proliferation of breast cancer cells by GPER-mediated signaling pathways

Tetrachlorobisphenol A (TCBPA), a chlorinated derivative of bisphenol A, is an endocrine disruptor based on interaction with nuclear estrogen receptor alpha (ERα). However, there is only limited data on the mechanisms through which TCBPA-associated estrogenic activity is related to the membrane G protein-coupled estrogen receptor (GPER) pathway. In this study, three human breast cancer cell lines-MCF-7, SKBR3, and MDA-MB-231 cells were used to evaluate whether, as well as how, TCBPA at concentration range of 0.001-50 μM affect cell proliferation. The role of GPER signaling in TCBPA-induced cell proliferation was studied by analyzing the protein expression and mRNA levels of relevant signal targets. The results showed that low concentrations of TCBPA significantly induced the proliferation of MCF-7, SKBR3, and MDA-MB-231 cells, with MCF-7 cells being the most sensitive to TCBPA exposure. Low-concentration TCBPA also upregulated the expression of GPER, CyclinD1, c-Myc, and c-Fos proteins, as well as increased the phosphorylation of extracellular signal-regulated-kinase 1/2 (Erk1/2) and protein kinase B (Akt). Additionally, the mRNA levels of genes associated with estrogen signaling pathways also increased upon exposure to TCBPA. However, the phosphorylation of Erk1/2 and Akt decreased when the cells were treated with GPER inhibitor G15 and phosphatidylinositide 3-kinase (PI3K) inhibitor wortmannin (WM) prior to TCBPA exposure. Besides, the increased proliferation of breast cancer cells induced by TCBPA were also inhibited. In ERα-positive MCF-7 cells, TCBPA also upregulated ERα expression, and ERα was found to interact with GPER-mediated signaling. The results indicate that GPER activates the PI3K/Akt and Erk1/2 signal cascades to drive the cell proliferation observed for low concentrations of TCBPA. The presented results suggest a new mechanism by which TCBPA exerts estrogenic action in breast cancer cells, namely, GPER signaling in an ERα-independent manner, and also highlights the potential risks to human health of the usage of TCBPA.

Contribution of RAGE axis activation to the association between metabolic syndrome and cancer

Far beyond the compelling proofs supporting that the metabolic syndrome represents a risk factor for diabetes and cardiovascular diseases, a growing body of evidence suggests that it is also a risk factor for different types of cancer. However, the involved molecular mechanisms underlying this association are not fully understood, and they have been mainly focused on the individual contributions of each component of the metabolic syndrome such as obesity, hyperglycemia, and high blood pressure to the development of cancer. The Receptor for Advanced Glycation End-products (RAGE) axis activation has emerged as an important contributor to the pathophysiology of many clinical entities, by fueling a chronic inflammatory milieu, and thus supporting an optimal microenvironment to promote tumor growth and progression. In the present review, we intend to highlight that RAGE axis activation is a crosswise element on the potential mechanistic contributions of some relevant components of metabolic syndrome into the association with cancer.

The emerging role of estrogen related receptorα in complications of non-small cell lung cancers

Approximately 85% of lung cancer cases are recognized as non-small cell lung cancer (NSCLC) with a perilous (13–17%) 5-year survival in Europe and the USA. Although tobacco smoking has consistently emerged as the leading cause of NSCLC complications, its consequences are distinctly manifest with respect to sex bias, due to differential gene and sex hormone expression. Estrogen related receptor α (ERRα), a member of the nuclear orphan receptor superfamily is normally expressed in the lungs, and activates various nuclear genes without binding to the ligands, such as estrogens. In NSCLC ERRα expression is significantly higher compared with healthy individuals. It is well established ERα and ERβ‚ have 93% and 60% identity in the DNA and ligand binding domains, respectively. ERα and ERRα have 69% (70% with ERRα-1) and 34% (35% with ERRα-1) identity, respectively; ERRα and ERRβ‚ have 92 and 61% identity, respectively. However, whether there is distinctive ERRα interaction with mammalian estrogens or concurrent involvement in non-ER signalling pathway activation is not known. Relevant to NSCLC, ERRα promotes proliferation, invasion and migration by silencing the tumor suppressor proteins p53 and pRB, and accelerates G₂-M transition during cell division. Epithelial to mesenchymal transition (EMT) and activation of Slug (an EMT associated transcription factor) are the prominent mechanisms by which ERRα activates NSCLC metastasis. Based on these observations, the present article focuses on the feasibility of antiERRα therapy alone and in combination with antiER as a therapeutic strategy for NSCLC complications.

Receptor for Advanced Glycation End Products (RAGE) and Its Polymorphic Variants as Predictive Diagnostic and Prognostic Markers of NSCLCs: a Perspective

PURPOSE OF REVIEW

Non-small cell lung cancers (NSCLCs) account for ~ 85% of all lung cancers, and 5-year survival in Europe and the USA is ~ 13-17%. In this review, we focus on the significance of Receptor for Advanced Glycation End products (RAGE) as a diagnostic or post-therapeutic prognostic marker for various forms of NSCLCs.

RECENT FINDINGS

The lungs have the highest levels of basal RAGE expression in mammals. The physiologic RAGE in lungs may be involved in adhesion and spreading of AT-1 cells and maintenance of pulmonary homeostasis. However, high level expression of RAGE complicates various diseases including acute lung injury. In NSCLCs, while a number of studies report decreased RAGE expression, inferring a protective role, others suggest that RAGE expression may contribute to NSCLC pathogenesis. Genetic polymorphisms of RAGE are reportedly associated with NSCLC development and complications. RAGE and its polymorphic variants may be useful diagnostic or post-therapeutic prognostic markers of NSCLCs.

Perspectives on signaling for biological- and processed food-related advanced glycation end-products and its role in cancer progression

Receptor for advanced glycation end-products (RAGE) is a multifunctional receptor binds a broad spectrum of ligands and mediates responses to cell damage and stress conditions. It also activates programs leading to acute and chronic inflammation and implicated in several pathological diseases, including cancer. In this review, we presented the non-enzymatic reaction of reducing sugar with the amino groups of proteins, lipids, and nucleic acids. This reaction initiates a complex series of rearrangements and dehydrations, and then produces a class of irreversibly cross-linked heterogeneous fluorescent moieties, termed advanced glycation end products (AGEs). There is a growing body of evidence that interaction of processes food-related AGEs with a cell surface receptor RAGE brings out the generation of oxidative stress and subsequently evokes proliferative, angiogenic and inflammatory reactions, thereby being involved in the development and progression of various types of cancers. This review is an insightful assessment of molecular mechanisms through which RAGE signaling contributes to the enhancement and survival of the tumorigenic cell. Here we summarize the procurement of individual ligands of RAGE like amphoterin, calcium-binding proteins, and resultant mediation of RAGE signaling pathway, which partially can elucidate the elevated risk of several cancers. Besides, we summarize many factors or conditions including APE1 (apurinic/apyrimidinic endonuclease 1), retinol mutations, retinoblastoma (Rb), proteinase 3 (PR3) hypoxia and so on through which RAGE signaling presents an establishment of cancerous environment. Additionally, we also reviewed some recent findings that give shreds of evidence for presenting the role of RAGE and its ligands in the advanced stage of cancers.

The Interaction Test of Binary Mixtures of Endocrine-Disrupting Chemicals Using In Vitro Bioassays

Typical environmental endocrine-disrupting chemicals (EDCs) such as estradiol valerate (EV), diethylstilbestrol (DES), di-2-ethylhexyl phthalate (DEHP), mono-2-ethylhexyl phthalate (MEHP), and bisphenol A (BPA) have a strong reproductive and developmental toxicity at low concentrations. However, information on their joint toxicity is scarce. In this study, we evaluated the combined effects of EV and other four EDCs (DES, DEHP, MEHP, and BPA) on the human breast MCF-7 cells by detecting the cell proliferation, intracellular reactive oxygen species (ROS) levels, and estrogen receptor alpha (ERα) protein expression using equal concentration ratio method. The results showed that, after exposure for 24, 48, and 72 h, single EV, DES, and BPA can promote the proliferation of MCF-7 human breast cancer cells, and EV has the strongest effect in inducing cell proliferation. DEHP and MEHP cannot induce MCF-7 cell proliferation for all exposure time, while cell proliferation induced by EV was significantly attenuated by DES, BPA, DEHP, and MEHP when they mixed with EV. For intracellular ROS, single EV, BPA, DES, DEHP, and MEHP elevated intracellular ROS levels for different exposure time. Similar to the cell proliferation, DES and BPA decreased intracellular ROS levels induced by EV when they mixed with EV for 24 h. EV, DES, and BPA exposed alone or combined with EV upregulated the ERα protein expression. However, DEHP and MEHP exposed alone or combined with EV had no effect on ERα protein expression, indicating that DEHP or MEHP could attenuate ERα protein expression upregulated by EV. These results showed that the joint toxicity of binary mixtures of EV and other EDCs do not interact in a synergistic fashion in inducing cell proliferation, intracellular ROS levels, and ERα protein expression. These findings have important implications in the human risk assessments of EV mixed with other EDCs in the environment.

Advanced glycation end products (AGEs), protein aggregation and their cross talk: new insight in tumorigenesis

Protein glycation and protein aggregation are two distinct phenomena being observed in cancer cells as factors promoting cancer cell viability. Protein aggregation is an abnormal interaction between proteins caused as a result of structural changes in them after any mutation or environmental assault. Protein aggregation is usually associated with neurodegenerative diseases like Alzheimer's and Parkinson's, but of late, research findings have shown its association with the development of different cancers like lung, breast and ovarian cancer. On the contrary, protein glycation is a cascade of irreversible nonenzymatic reaction of reducing sugar with the amino group of the protein resulting in the modification of protein structure and formation of advanced glycation end products (AGEs). These AGEs are reported to obstruct the normal function of proteins. Lately, it has been reported that protein aggregation occurs as a result of AGEs. This aggregation of protein promotes the transformation of healthy cells to neoplasia leading to tumorigenesis. In this review, we underline the current knowledge of protein aggregation and glycation along with the cross talk between the two, which may eventually lead to the development of cancer.

Antibody drug conjugates against the receptor for advanced glycation end products (RAGE), a novel therapeutic target in endometrial cancer

Background

The treatment of endometrial cancer (EC), the most common gynecological cancer, is currently hampered by the toxicity of current cytotoxic agents, meaning novel therapeutic approaches are urgently required.

Methods

A cohort of 161 patients was evaluated for the expression of the receptor for advanced glycation end products (RAGE) in endometrial tissues. The present study also incorporates a variety of in vitro methodologies within multiple cell lines to evaluate RAGE expression and antibody-drug conjugate efficacy, internalisation and intercellular trafficking. Additionally, we undertook in vivo bio-distribution and toxicity evaluation to determine the suitability of our chosen therapeutic approach, together with efficacy studies in a mouse xenograft model of disease.

Results

We have identified an association between over-expression of the receptor for advanced glycation end products (RAGE) and EC (H-score = Healthy: 0.46, SD 0.26; Type I EC: 2.67, SD 1.39; Type II EC: 2.20, SD 1.34; ANOVA, p < 0.0001). Furthermore, increased expression was negatively correlated with patient survival (Spearman’s Rank Order Correlation: ρ = − 0.3914, p < 0.05). To exploit this association, we developed novel RAGE-targeting antibody drug conjugates (ADC) and demonstrated the efficacy of this approach. RAGE-targeting ADCs were up to 100-fold more efficacious in EC cells compared to non-malignant cells and up to 200-fold more cytotoxic than drug treatment alone. Additionally, RAGE-targeting ADCs were not toxic in an in vivo pre-clinical mouse model, and significantly reduced tumour growth in a xenograft mouse model of disease.

Conclusions

These data, together with important design considerations implied by the present study, suggest RAGE-ADCs could be translated to novel therapeutics for EC patients.

Advanced Glycation End Products (AGEs), Glutathione and Breast Cancer: Factors, Mechanism and Therapeutic Interventions

Background:

Advanced Glycation End products (AGEs) are basically the end result of glycation of proteins and/or lipids in the presence of sugars. Specific cases of hyperglycemia have been reported with increased propensity of generation of AGEs. Many chronic and deadly diseases such as diabetes, cancer and neurodegenerative disorders have been known to be caused as a result of generation of AGEs. The role of glutathione (GSH) metabolism and its intricate association with AGEs have also been well established in breast cancer prognosis and treatment. To understand the etiology, mechanism and production of AGEs along with clinical relevance of Receptors for Advanced Glycation End-products (RAGE) and RAGE ligands, their interplay with GSH is of paramount importance especially in relation to breast cancer.

Methods:

The available literature using PubMed, National Library of Medicine database, Web of Science and SCOPUS indexed, Science Direct and other prestigious journals have been systematically reviewed using the keywords: advanced glycation end-products, breast cancer, glutathione RAGE, and AGEs inhibitors. This narrative review of all the relevant papers with significant citations has led us to have greater insight into the action mechanism and potential therapeutic significance of AGEs inhibitors.

Results:

Targeting breast cancer with the specific immunoglobulins and with other therapeutic interventions is needed to inhibit the generation of AGEs and manage glutathione expression, thus having strong implications in the management of breast cancer. Many RAGE ligands such as HMGB1, S100P, S100A8, S100A9 etc. have been known to enhance RAGE expression which may further lead to increased proliferation, migration and metastatic nature of tumor cells. Hence, RAGE and RAGE ligands in a close linkup with GSH may prove to be effective therapeutic markers of severity of breast cancer and for angiogenesis of tumor.

Conclusion:

This review provides a strong platform to comprehend the etiology, mechanism and production of AGEs and glutathione along with the agents which can block their production, paving a way for the therapeutic intervention and an amicable solution to treat and manage breast cancer.

Low-concentration BPF induced cell biological responses by the ERα and GPER1-mediated signaling pathways in MCF-7 breast cancer cells

Bisphenol F (BPF), one of the alternatives to bisphenol A (BPA), can induce proliferation through the nuclear estrogen receptor ERα (estrogen receptor alpha) pathway in human breast cancer MCF-7 cells. However, the roles of membrane estrogen receptor GPER1 (G-protein-coupled receptor 1)-mediated signaling pathways in MCF-7 cell proliferation caused by BPF are unclear. The influence of BPF on MCF-7 cells was evaluated in terms of cell proliferation, intracellular calcium (Ca²⁺) fluctuations, and reactive oxygen species (ROS) generation. The molecular mechanisms of the cellular responses to low doses of BPF were studied through detecting the activations of ERα and GPER1-regulated PI3K/PKB or AKT (phosphatidylinotidol 3-kinase/protein kinase B) and ERK1/2 (extracellular-signa1-regulated kinase 1/2) signals. At 0.01-1 μM, BPF significantly promoted cell proliferation and elevated the levels of intracellular ROS and Ca²⁺. At these concentrations, BPF also significantly upregulated protein expressions of ERα, GPER1, c-myc, and cyclin D and phosphorylations of PKB and ERK1/2. Specific signal inhibitors decreased PKB and ERK1/2 phosphorylations and attenuated the effects of BPF. Silencing of GPER1 also significantly decreased BPF-induced cell proliferation. These results indicate that activating the GPER1-PI3K/PKB and ERK1/2 signals by low doses of BPF can regulate the response of MCF-7 cells and that ERα also influences the effects of exposure to BPF on the cells. The present study suggests a new mechanism by which BPF exerts relevant estrogenic action in cancer cells and also highlights the potential risks in using BPF as an alternative to BPA.

Ethinylestradiol and Levonorgestrel as Active Agents in Normal Skin, and Pathological Conditions Induced by UVB Exposure: In Vitro and In Ovo Assessments

The link between melanoma development and the use of oral combined contraceptives is not fully elucidated, and the data concerning this issue are scarce and controversial. In the present study, we show that the components of oral contraceptives, ethinylestradiol (EE), levonorgestrel (LNG), and their combination (EE + LNG) ± UVB (ultraviolet B radiation) induced differential effects on healthy (human keratinocytes, fibroblasts, and primary epidermal melanocytes, and murine epidermis cells) and melanoma cells (human—A375 and murine—B164A5), as follows: (i) at low doses (1 µM), the hormones were devoid of significant toxicity on healthy cells, but in melanoma cells, they triggered cell death via apoptosis; (ii) higher doses (10 µM) were associated with cytotoxicity in all cells, the most affected being the melanoma cells; (iii) UVB irradiation proved to be toxic for all types of cells; (iv) UVB irradiation + hormonal stimulation led to a synergistic cytotoxicity in the case of human melanoma cells—A375 and improved viability rates of healthy and B164A5 cells. A weak irritant potential exerted by EE and EE + LNG (10 µM) was assessed by the means of a chick chorioallantoic membrane assay. Further studies are required to elucidate the hormones’ cell type-dependent antimelanoma effect and the role played by melanin in this context.

Advanced glycation end products are elevated in estrogen receptor-positive breast cancer patients, alter response to therapy, and can be targeted by lifestyle intervention

Purpose

Lifestyle factors associated with personal behavior can alter tumor-associated biological pathways and thereby increase cancer risk, growth, and disease recurrence. Advanced glycation end products (AGEs) are reactive metabolites produced endogenously as a by-product of normal metabolism. A Western lifestyle also promotes AGE accumulation in the body which is associated with disease phenotypes through modification of the genome, protein crosslinking/dysfunction, and aberrant cell signaling. Given the links between lifestyle, AGEs, and disease, we examined the association between dietary-AGEs and breast cancer.

Methods

We evaluated AGE levels in bio-specimens from estrogen receptor-positive (ER+) and estrogen receptor-negative (ER−) breast cancer patients, examined their role in therapy resistance, and assessed the ability of lifestyle intervention to reduce circulating AGE levels in ER+ breast cancer survivors.

Results

An association between ER status and AGE levels was observed in tumor and serum samples. AGE treatment of ER+ breast cancer cells altered ERα phosphorylation and promoted resistance to tamoxifen therapy. In a proof of concept study, physical activity and dietary intervention was shown to be viable options for reducing circulating AGE levels in breast cancer survivors.

Conclusions

There is a potential prognostic and therapeutic role for lifestyle derived AGEs in breast cancer. Given the potential benefits of lifestyle intervention on incidence and mortality, opportunities exist for the development of community health and nutritional programs aimed at reducing AGE exposure in order to improve breast cancer prevention and treatment outcomes.

Electronic supplementary material

The online version of this article (10.1007/s10549-018-4992-7) contains supplementary material, which is available to authorized users.

Differential Expression of RAGE, EGFR and Ki-67 in Primary Tumors and Lymph Node Deposits of Breast Carcinoma

Background:

Breast cancer is a complex disease that results from the inheritance of a number of susceptible genes. Intensive search wok was conducted world-wide on molecular bases of breast cancer in order to achieve the best therapeutic modalities; however, breast cancer still remains a challengeable task. It is very important to determine if the biological parameters in metastatic regional lymph nodes are similar to that in the primary breast cancer because therapy is indicated for patients with synchronous metastatic regional lymph nodes of breast cancer. Difference in therapeutic response in cases of breast cancer may be assumed partially to variability in the biological behavior of tumor tissue in primary breast cancer and lymph node metastasis.

Aim:

Our aim is to evaluate any variability in the expression of three types of tissue markers in both the primary breast tumors and corresponding axillary lymph nodes in order to expect the targeted therapeutic effect on both sites.

Material and Methods:

Three markers from different categories; RAGE, EGFR and Ki-67 were immunohistochemicalyl studied for their expression in biopsy specimens from primary breast tumors and their corresponding axillary lymph nodes.

Results:

There was a statistically significant difference in the expression of these markers between benign and malignant breast lesions. Although we found some differences in the expression of the three studied markers between primary breast cancer and corresponding axillary lymph nodes, yet these variations were mostly not statistically significant.

Conclusion:

Our findings support the validity of anti-RAGE and anti-EGFR therapy for treatment of both primary and nodal metastatic breast cancer in immunopositive cases.

Low-concentration BPAF- and BPF-induced cell biological effects are mediated by ROS in MCF-7 breast cancer cells

Reactive oxygen species (ROS) induced by bisphenol A (BPA) have been implicated in cellular oxidative damage and carcinogenesis. It is not known whether the potential alternatives of BPA, bisphenol AF (BPAF), and bisphenol F (BPF) can also induce ROS involved in mediating biological responses. This study evaluated the toxicity of BPAF and BPF on cell proliferation, DNA damage, intracellular calcium homeostasis, and ROS generation in MCF-7 human breast cancer cells. The results showed that BPAF at 0.001-1 μM and BPF at 0.01-1 μM significantly increased cell viability and at 25 and 50 μM, both compounds decreased cell viability. At 0.01-10 μM, both BPAF and BPF increased DNA damage and significantly elevated ROS and intracellular Ca²⁺ levels in MCF-7 cells. These biological effects were attenuated by the ROS scavenger N-acetylcysteine (NAC), indicating that ROS played a key role in the observed biological effects of BPAF and BPF on MCF-7 cells. These findings can deepen our understanding on the toxicity of BPAF and BPF, and provide basis data to further evaluate the potential health harm and establish environmental standard of BPAF and BPF.

Biological impact of advanced glycation endproducts on estrogen receptor-positive MCF-7 breast cancer cells

Diabetes mellitus potentiates the risk of breast cancer. We have previously described the pro-tumorigenic effects of advanced glycation endproducts (AGEs) on estrogen receptor (ER)-negative MDA-MB-231 breast cancer cell line mediated through the receptor for AGEs (RAGE). However, a predominant association between women with ER-positive breast cancer and type 2 diabetes mellitus has been reported. Therefore, we have investigated the biological impact of AGEs on ER-positive human breast cancer cell line MCF-7 using in vitro cell-based assays including cell count, migration, and invasion assays. Western blot, FACS analyses and quantitative real time-PCR were also performed. We found that AGEs at 50-100μg/mL increased MCF-7 cell proliferation and cell migration associated with an enhancement of pro-matrix metalloproteinase (MMP)-9 activity, without affecting their poor invasiveness. However, 200μg/mL AGEs inhibited MCF-7 cell proliferation through induction of apoptosis indicated by caspase-3 cleavage detected using Western blotting. A phospho-protein array analysis revealed that AGEs mainly induce the phosphorylation of extracellular-signal regulated kinase (ERK)1/2 and cAMP response element binding protein-1 (CREB1), both signaling molecules considered as key regulators of AGEs pro-tumorigenic effects. We also showed that AGEs up-regulate RAGE and ER expression at the protein and transcript levels in MCF-7 cells, in a RAGE-dependent manner after blockade of AGEs/RAGE interaction using neutralizing anti-RAGE antibody. Throughout the study, BSA had no effect on cellular processes. These findings pave the way for future studies investigating whether the exposure of AGEs-treated ER-positive breast cancer cells to estrogen could lead to a potentiation of breast cancer development and progression.

Hypoxia driven glycation: Mechanisms and therapeutic opportunities

Tumor masses are deprived of oxygen and characterized by enhanced glucose uptake followed by glycolysis. Elevated glucose levels induce non-enzymatic glycosylation or glycation of proteins which leads to accumulation of advanced glycation end products (AGE). These AGE molecules bind to their respective receptors called the receptor for advanced glycation end products (RAGE) and initiate several aberrant signaling pathways leading to onset of diseases such as diabetes, Alzheimer's, atherosclerosis, heart failure and cancer. The role of AGE in cancer progression is being extensively studied in recent years. As cancer cells are hypoxic in nature and adapted to glycolysis, which induces glycation, its effects need to be understood in greater detail. Since AGE-RAGE signaling is involved in cancer progression, inhibition of AGE-RAGE interaction could be a potential therapeutic target. The purpose of this review is to highlight the role of AGE-RAGE interaction in hypoxic cancer cells.

MiR-138: A promising therapeutic target for cancer

MicroRNAs are small noncoding RNAs which regulate gene expressions at post-transcriptional level by binding to the 3'-untranslated region of target messenger RNAs. Growing evidences highlight their pivotal roles in various biological processes of human cancers. Among them, miR-138, generating from two primary transcripts, pri-miR-138-1 and pri-miR-138-2, expresses aberrantly in different cancers and is extensively studied in cancer network. Importantly, studies have shown that miR-138 acts as a tumor suppressor by targeting many target genes, which are related to proliferation, apoptosis, invasion, and migration. Additionally, some researches also discover that miR-138 can sensitize tumors to chemotherapies. In this review, we summarize the expression of miR-138 on regulatory mechanisms and tumor biological processes, which will establish molecular basis on the usage of miR-138 in clinical applications in the future.

Activation of G protein-coupled receptor 30 by thiodiphenol promotes proliferation of estrogen receptor α-positive breast cancer cells

Many studies have been shown that environmental estrogen bisphenol A (BPA) can activate nuclear receptor (estrogen receptor alpha, ERα) or membrane receptor (G-protein-coupled receptor, GPR30) in breast cancer cells and exerts genomic or nongenomic actions inducing cell proliferation. 4,4'-thiodiphenol (TDP) as one of BPA derivatives exhibits more potent estrogenic activity than BPA does. However, comparatively little is known about the ways in which TDP interferes with these signaling pathways and produces cell biological changes. This study evaluated the effect of TDP on cell viability, reactive oxygen species (ROS) formation, and intercellular calcium (Ca²⁺) fluctuation in MCF-7 breast cancer cells. The underlying molecular mechanism of cell proliferation induced by TDP was analyzed by examining the activation of ERα and GPR30-mediated phosphatidylinotidol 3-kinase/protein kinase B (PI3K/AKT) and extracellular-signa1regulated kinase (ERK1/2) signaling pathways. The results showed that exposure to 0.1-10 μM TDP for 24, 48, and 72 h significantly increased viability of MCF-7 cells. At the same concentration range, TDP exposure for 3 and 24 h markedly elevated ROS production and intracellular Ca²⁺ levels. In addition, 0.01-1 μM TDP significantly increased the expression of ERα, GPR30, p-AKT and p-ERK1/2 protein. Specific protein inhibitors blocked phosphorylation of ERK1/2 and AKT and decreased TDP-induced cell proliferation. These findings show that TDP activated the GPR30-PI3K/AKT and ERK1/2 pathways, and the resulting interaction with ERα stimulated MCF-7 cell proliferation. Our results indicate a novel mechanism through which TDP may exert relevant estrogenic action in ERα positive cancer cells.

In vitro profiling of toxicity and endocrine disrupting effects of bisphenol analogues by employing MCF-7 cells and two-hybrid yeast bioassay

The potentially adverse health implications of bisphenol A (BPA) have led to increasing use of alternative bisphenols (BPs). However, little is known about the toxicity of alternative BPs. In this study, the cytotoxicity, genotoxicity, intracellular ROS formation, and Ca²⁺ fluctuation effects of BPs on MCF-7 cells were evaluated. At the same time, the estrogenic and thyroidal hormone effect potentials of six BPs were also evaluated using two-hybrid yeast bioassay. The results showed that most BPs at 0.01-1 μM significantly increased cell viability in MCF-7 cells and at higher exposure concentrations of 25-100 μM, they caused a significant decrease of cell viability. At the same time, these BPs also at 25-100 μM significantly increased LDH release of MCF-7 cells. In addition, several BPs at 10-50 μM resulted in a significantly concentration-depended increase in DNA-damaging effect on MCF-7 cells and elevated ROS production. Most BPs at 0.0001-10 μM significantly increased intracellular Ca²⁺ level. These results showed that bisphenol AF (BPAF) and thiodiphenol (TDP) exerted cell biological effect, estrogenic, and thyroidal effect potentials greater than those of BPA. The cytotoxicity and endocrine disrupting effects of other BPs are similar to or slightly lower than those of BPA. Therefore, as potential alternatives to BPA, endocrine disrupting effects and potential health harm of alternative BPs to human can also not be ignored. © 2016 Wiley Periodicals, Inc. Environ Toxicol 32: 278-289, 2017.

Inorganic polyphosphate promotes cyclin D1 synthesis through activation of mTOR/Wnt/β-catenin signaling in endothelial cells

Essentials Polyphosphate (polyP) activates mTOR but its role in Wnt/β-catenin signaling is not known. PolyP-mediated cyclin D1 expression (β-catenin target gene) was monitored in endothelial cells. PolyP and boiled platelet-releasates induced the expression of cyclin D1 by similar mechanisms. PolyP establishes crosstalk between mTOR and Wnt/β-catenin signaling in endothelial cells.

SUMMARY

Background Inorganic polyphosphate (polyP) elicits intracellular signaling responses in endothelial cells through activation of mTOR complexes 1 and 2. Glycogen synthase kinase 3 (GSK-3) is known to be a negative regulator of mTOR and Wnt/β-catenin signaling pathways. Objective The objective of this study was to investigate the effect of polyP on the expression, degradation and subcellular localization of the Wnt/β-catenin target gene, cyclin D1, in endothelial cells. Methods Regulation of cyclin D1 expression, phosphorylation and subcellular localization by polyP or platelet releasates was monitored in the absence and presence of pharmacological inhibitors and/or siRNA for specific molecules of the upstream mTOR/Wnt/β-catenin signaling network by established methods. Results Both synthetic polyP and boiled-platelet releasates induced the phosphorylation-dependent inactivation of GSK-3, thereby increasing the expression and nuclear localization, but inhibiting the degradation of cyclin D1. Inhibitors of mTORC1 (PI3K, AKT, PLC, PKC), rapamycin and siRNA for raptor (mTORC1-specific component) and β-catenin, all inhibited polyP-mediated regulation of cyclin D1 expression, phosphorylation and subcellular localization in endothelial cells. The signaling effect of polyP was effectively inhibited by the recombinant extracellular domain of the receptor for advanced glycation end products (RAGE) and/or by the RAGE siRNA. Specific pharmacological inhibitors and siRNA knockdown of ERK1/2 and NF-κB pathways indicated that polyP-mediated cyclin D1 expression and nuclear localization are IKKɑ and ERK1/2 dependent, whereas its inhibitory effect on phosphorylation-dependent degradation of cyclin D1 is IKKβ-dependent. Conclusion We conclude that a RAGE-dependent polyP-mediated crosstalk between mTOR and the GSK-3/Wnt/β-catenin signaling network can modulate important physiological processes in endothelial cells.

Role of receptor for advanced glycation end products in the complication and progression of various types of cancers

BACKGROUND

Receptor for advanced glycation end-products popularly known as RAGE is a cell surface immunoglobulin class of molecule, binds with multiple ligands and therefore considered as a multi-ligand receptor. Use of RAGE deficient mice (RAGE(-/-)) as well as established mouse models pertaining to inflammation-associated carcinogenesis such as that of chemically induced carcinogenesis and colitis associated cancer provides a direct genetic evidence for a likelihood novel role of RAGE in cancer, with respect to its ability to lead cancer cell proliferation and survival. Besides inflammation, interaction of RAGE with its various ligands enhances oxidative stress both in cancerous and noncancerous cells which further complicates the progression of cancers.

SCOPE OF REVIEW

Till date, no single review article has discussed the mechanism of RAGE dependent complication of cancers, particularly the role of RAGE in cancer cell proliferation, angiogenesis, survival and anti-apoptosis needs to be discussed.

MAJOR CONCLUSION

RAGE enhances the number of cancer cells by activating the cell cycle proteins (e.g., cyclin D1), anti-apoptotic proteins (e.g., BCl2), prosurvival (AKT) and autophagic proteins. Role of RAGE has also been detected in formation of new blood vessels (angiogenesis) in the cancer cells and activation of myeloid derived suppressor cells (MDSCs).

GENERAL SIGNIFICANCE

This review article describes the role of RAGE in the complication of various types of cancers and the possible usefulness of RAGE dependent therapy to confront cancers in a stronger magnitude.

RAGE mediates S100A7-induced breast cancer growth and metastasis by modulating the tumor microenvironment

RAGE is a multifunctional receptor implicated in diverse processes including inflammation and cancer. In this study, we report that RAGE expression is upregulated widely in aggressive triple-negative breast cancer (TNBC) cells, both in primary tumors and in lymph node metastases. In evaluating the functional contributions of RAGE in breast cancer, we found that RAGE-deficient mice displayed a reduced propensity for breast tumor growth. In an established model of lung metastasis, systemic blockade by injection of a RAGE neutralizing antibody inhibited metastasis development. Mechanistic investigations revealed that RAGE bound to the proinflammatory ligand S100A7 and mediated its ability to activate ERK, NF-κB, and cell migration. In an S100A7 transgenic mouse model of breast cancer (mS100a7a15 mice), administration of either RAGE neutralizing antibody or soluble RAGE was sufficient to inhibit tumor progression and metastasis. In this model, we found that RAGE/S100A7 conditioned the tumor microenvironment by driving the recruitment of MMP9-positive tumor-associated macrophages. Overall, our results highlight RAGE as a candidate biomarker for TNBCs, and they reveal a functional role for RAGE/S100A7 signaling in linking inflammation to aggressive breast cancer development.