MicroRNA-497 downregulation contributes to cell proliferation, migration, and invasion of estrogen receptor alpha negative breast cancer by targeting estrogen-related receptor alpha

Lactate-Induced HBEGF Shedding and EGFR Activation: Paving the Way to a New Anticancer Therapeutic Opportunity

Cancer cells can release EGF-like peptides, acquiring the capacity of autocrine stimulation via EGFR-mediated signaling. One of these peptides (HBEGF) was found to be released from a membrane-bound precursor protein and is critically implicated in the proliferative potential of cancer cells. We observed that the increased lactate levels characterizing neoplastic tissues can induce the release of uPA, a protease promoting HBEGF shedding. This effect led to EGFR activation and increased ERK1/2 phosphorylation. Since EGFR-mediated signaling potentiates glycolytic metabolism, this phenomenon can induce a self-sustaining deleterious loop, favoring tumor growth. A well characterized HBEGF inhibitor is CRM197, a single-site variant of diphtheria toxin. We observed that, when administered individually, CRM197 did not trigger evident antineoplastic effects. However, its association with a uPA inhibitor caused dampening of EGFR-mediated signaling and apoptosis induction. Overall, our study highlights that the increased glycolytic metabolism and lactate production can foster the activated state of EGFR receptor and suggests that the inhibition of EGFR-mediated signaling can be attempted by means of CRM197 administered with an appropriate protease inhibitor. This attempt could help in overcoming the problem of the acquired resistance to the conventionally used EGFR inhibitors.

MicroRNA signature of stromal-epithelial interactions in prostate and breast cancers

Stromal-epithelial communication is an absolute necessity when it comes to the morphogenesis and pathogenesis of solid tissues, including the prostate and breast. So far, signalling pathways of several growth factors have been investigated. Besides such chemical factors, non-coding RNAs such as miRNAs have recently gained much interest because of their variety and complexity of action. Prostate and breast tissues being highly responsive to steroid hormones such as androgen and estrogen, respectively, it is not surprising that a huge set of available literature critically investigated the interplay between such hormones and miRNAs, especially in carcinogenesis. This review showcases our effort to highlight hormonally-related miRNAs that also somehow perturb the regular stromal-epithelial interactions during carcinogenesis in the prostate and breast. In future, we look forward to exploring how hormonal changes in the tissue microenvironment bring about miRNA-mediated changes in stromal-epithelial interactome in carcinogenesis and cancer progression.

ERRα: unraveling its role as a key player in cell migration

Cell migration is essential throughout the life of multicellular organisms, and largely depends on the spatial and temporal regulation of cytoskeletal dynamics, cell adhesion and signal transduction. Interestingly, Estrogen-related receptor alpha (ERRα) has been identified as a major regulator of cell migration in both physiological and pathological conditions. ERRα is an orphan member of the nuclear hormone receptor superfamily of transcription factors and displays many biological functions. ERRα is a global regulator of energy metabolism, and it is also highly involved in bone homeostasis, development, differentiation, immunity and cancer progression. Importantly, in some instances, the regulation of these biological processes relies on the ability to orchestrate cell movements. Therefore, this review describes how ERRα-mediated cell migration contributes not only to tissue homeostasis but also to tumorigenesis and metastasis, and highlights the molecular and cellular mechanisms by which ERRα finely controls the cell migratory potential.

Non-Coding RNAs Modulating Estrogen Signaling and Response to Endocrine Therapy in Breast Cancer

The largest part of human DNA is transcribed into RNA that does not code for proteins. These non-coding RNAs (ncRNAs) are key regulators of protein-coding gene expression and have been shown to play important roles in health, disease and therapy response. Today, endocrine therapy of ERα-positive breast cancer (BC) is a successful treatment approach, but resistance to this therapy is a major clinical problem. Therefore, a deeper understanding of resistance mechanisms is important to overcome this resistance. An increasing amount of evidence demonstrate that ncRNAs affect the response to endocrine therapy. Thus, ncRNAs are considered versatile biomarkers to predict or monitor therapy response. In this review article, we intend to give a summary and update on the effects of microRNAs (miRNAs), long non-coding RNAs (lncRNAs) and circular RNAs (circRNAs) on estrogen signaling in BC cells, this pathway being the target of endocrine therapy, and their role in therapy resistance. For this purpose, we reviewed articles on these topics listed in the PubMed database. Finally, we provide an assessment regarding the clinical use of these ncRNA types, particularly their circulating forms, as predictive BC biomarkers and their potential role as therapy targets to overcome endocrine resistance.

Multifaceted Transcriptional Network of Estrogen-Related Receptor Alpha in Health and Disease

Estrogen-related receptors (ERRα, β and γ in mammals) are orphan members of the nuclear receptor superfamily acting as transcription factors. ERRs are expressed in several cell types and they display various functions in normal and pathological contexts. Amongst others, they are notably involved in bone homeostasis, energy metabolism and cancer progression. In contrast to other nuclear receptors, the activities of the ERRs are apparently not controlled by a natural ligand but they rely on other means such as the availability of transcriptional co-regulators. Here we focus on ERRα and review the variety of co-regulators that have been identified by various means for this receptor and their reported target genes. ERRα cooperates with distinct co-regulators to control the expression of distinct sets of target genes. This exemplifies the combinatorial specificity of transcriptional regulation that induces discrete cellular phenotypes depending on the selected coregulator. We finally propose an integrated view of the ERRα transcriptional network.

miR-137/ERRα axis mediates chemoresistance of nasopharyngeal carcinoma cells

Nasopharyngeal carcinoma (NPC) is the most common malignant tumor of the head and neck region and is characterized by an increased risk of developing chemoresistance after treatment. The present study demonstrated that estrogen-related receptor α (ERRα) was upregulated in cisplatin- and fluorouracil-resistant NPC cells. In addition, ERRα knockdown or treatment of cells with the ERRα inverse agonist XCT-790 attenuated the chemoresistance of NPC cells. Mechanistically, the increased expression of ERRα in chemoresistant cells was associated with enhanced mRNA stability. Bioinformatics analysis for screening microRNAs (miRs) regulating the expression of ERRα revealed that miR-137 was downregulated in chemoresistant NPC cells. Additionally, transfection of cells with miR-137 mimics reduced ERRα mRNA stability and increased the chemosensitivity of NPC cells. Furthermore, ERRα knockdown reduced glucose consumption, and lactate and ATP production rates in chemoresistant cells. The aforementioned findings suggested that the miR-137/ERRα-mediated metabolic programming could be involved in the chemoresistance of NPC cells.

Transcriptional Regulation of ROS Homeostasis by the ERR Subfamily of Nuclear Receptors

Reactive oxygen species (ROS) such as superoxide anion (O₂^•-) and hydrogen peroxide (H₂O₂) are generated endogenously by processes such as mitochondrial oxidative phosphorylation, or they may arise from exogenous sources like bacterial invasion. ROS can be beneficial (oxidative eustress) as signaling molecules but also harmful (oxidative distress) to cells when ROS levels become unregulated in response to physiological, pathological or pharmacological insults. Indeed, abnormal ROS levels have been shown to contribute to the etiology of a wide variety of diseases. Transcriptional control of metabolic genes is a crucial mechanism to coordinate ROS homeostasis. Therefore, a better understanding of how ROS metabolism is regulated by specific transcription factors can contribute to uncovering new therapeutic strategies. A large body of work has positioned the estrogen-related receptors (ERRs), transcription factors belonging to the nuclear receptor superfamily, as not only master regulators of cellular energy metabolism but, most recently, of ROS metabolism. Herein, we will review the role played by the ERRs as transcriptional regulators of ROS generation and antioxidant mechanisms and also as ROS sensors. We will assess how the control of ROS homeostasis by the ERRs can be linked to physiology and disease and the possible contribution of manipulating ERR activity in redox medicine.

miR-497-5p Decreased Expression Associated with High-Risk Endometrial Cancer

The current guidelines for diagnosis, prognosis, and treatment of endometrial cancer (EC), based on clinicopathological factors, are insufficient for numerous reasons; therefore, we investigated the relevance of miRNA expression profiles for the discrimination of different EC subtypes. Among the miRNAs previously predicted to allow distinguishing of endometrioid ECs (EECs) according to different grades (G) and from serous subtypes (SECs), we verified the utility of miR-497-5p. In ECs, we observed downregulated miR-497-5p levels that were significantly decreased in SECs, clear cell carcinomas (CCCs), and carcinosarcomas (CaSas) compared to EECs, thereby distinguishing EEC from SEC and rare EC subtypes. Significantly reduced miR-497-5p expression was found in high-grade ECs (EEC G3, SEC, CaSa, and CCC) compared to low-grade carcinomas (EEC G1 and mucinous carcinoma) and ECs classified as being in advanced FIGO (International Federation of Gynecology and Obstetrics) stages, that is, with loco-regional and distant spread compared to cancers located only in the uterus. Based on immunohistochemical features, lower miR-497-5p levels were observed in hormone-receptor-negative, p53-positive, and highly Ki-67-expressing ECs. Using a machine learning method, we showed that consideration of miR-497-5p expression, in addition to the traditional clinical and histopathologic parameters, slightly improves the prediction accuracy of EC diagnosis. Our results demonstrate that changes in miR-497-5p expression influence endometrial tumorigenesis and its evaluation may contribute to more precise diagnoses.

Regulation of microRNA-497 expression in human cancer

MicroRNAs (miRNAs/miRs) are a type of non-coding single-stranded RNA, with a length of ~22 nt, which are encoded by endogenous genes and are involved in the post-transcriptional regulation of gene expression in animals and plants. Studies have demonstrated that miRNAs play an important role in the occurrence, development, metastasis, diagnosis and treatment of cancer. In recent years, miR-497 has been identified as one of the key miRNAs in a variety of cancer types and has been shown to be downregulated in a variety of solid tumors. However, the regulation of miR-497 expression involves a complex network, which is affected by several factors. The aim of the present review was to summarize the mechanism of regulation of miR-497 expression at the pre-transcriptional and transcriptional levels in cancer, as well as the role of miR-497 expression imbalance in cancer diagnosis, treatment and prognosis. The regulatory mechanisms of miR-497 expression may aid in our understanding of the causes of miR-497 expression imbalance and provide a reference value for further research on the diagnosis and treatment of cancer.

Regulation of the expression of the estrogen related receptors (ERRs)

Estrogen related receptors (ERRα, β and γ in mammals) are orphan members of the nuclear receptor superfamily acting as transcription factors. ERRs are expressed in several tissues and cells and they display various physiological and pathological functions, controlling, amongst others and depending on the receptor, bone homeostasis, energy metabolism, embryonic stem cell pluripotency, and cancer progression. In contrast to classical nuclear receptors, the activities of the ERRs are not controlled by a natural ligand. Regulation of their activities thus rely on other means such as post-translational modification or availability of transcriptional co-regulators. In addition, regulation of their mere expression under given physiological or pathological conditions is a particularly important level of control. Here we discuss the mechanisms involved in the regulation of ERRs expression and the reported means to impact on it using pharmacological approaches.

Perspectives on the Role of Non-Coding RNAs in the Regulation of Expression and Function of the Estrogen Receptor

Estrogen receptors (ERs) comprise several nuclear and membrane-bound receptors with different tissue-specific functions. ERα and ERβ are two nuclear members of this family, whereas G protein-coupled estrogen receptor (GPER), ER-X, and Gq-coupled membrane estrogen receptor (Gq-mER) are membrane-bound G protein-coupled proteins. ERα participates in the development and function of several body organs such as the reproductive system, brain, heart and musculoskeletal systems. ERβ has a highly tissue-specific expression pattern, particularly in the female reproductive system, and exerts tumor-suppressive roles in some tissues. Recent studies have revealed functional links between both nuclear and membrane-bound ERs and non-coding RNAs. Several oncogenic lncRNAs and miRNAs have been shown to exert their effects through the modulation of the expression of ERs. Moreover, treatment with estradiol has been shown to alter the malignant behavior of cancer cells through functional axes composed of non-coding RNAs and ERs. The interaction between ERs and non-coding RNAs has functional relevance in several human pathologies associated with estrogen regulation, such as cancers, intervertebral disc degeneration, coronary heart disease and diabetes. In the current review, we summarize scientific literature on the role of miRNAs and lncRNAs on ER-associated signaling and related disorders.

miR-15/107 microRNA Gene Group: Characteristics and Functional Implications in Cancer

The miR-15/107 group of microRNAs (miRNAs) encloses 10 annotated human members and is defined based on the presence of the sequence AGCAGC near the mature miRNAs’ 5′ end. Members of the miR-15/107 group expressed in humans are highly evolutionarily conserved, and seven of these miRNAs are widespread in vertebrate species. Contrary to the majority of miRNAs, which recognize complementary sequences on the 3′UTR region, some members of the miR-15/107 group are peculiarly characterized by the ability to target the coding sequence (CDS) of their target mRNAs, inhibiting translation without strongly affecting their mRNA levels. There is compelling evidence that different members of the miR-15/107 group regulate overlapping lists of mRNA targets but also show target specificity. The ubiquitously expressed miR-15/107 gene group controls several human cellular pathways, such as proliferation, angiogenesis, and lipid metabolism, and might be altered in various diseases, such as neurodegenerative diseases and cancer. Intriguingly, despite sharing the same seed sequence, different members of this family of miRNAs may behave as oncomiRs or as tumor suppressor miRNAs in the context of cancer cells. This review discusses the regulation and functional contribution of the miR-15/107 group to the control of gene expression. Moreover, we particularly focus on the contribution of specific miR-15/107 group members as tumor suppressors in breast cancer, reviewing literature reporting their ability to function as major controllers of a variety of cell pathways and to act as powerful biomarkers in this disease.

Dissecting miRNA facilitated physiology and function in human breast cancer for therapeutic intervention

MicroRNAs (miRNAs) are key epigenomic regulators of biological processes in animals and plants. These small non coding RNAs form a complex networks that regulate cellular function and development. MiRNAs prevent translation by either inactivation or inducing degradation of mRNA, a major concern in post-transcriptional gene regulation. Aberrant regulation of gene expression by miRNAs is frequently observed in cancer. Overexpression of various 'oncomiRs' and silencing of tumor suppressor miRNAs are associated with various types of human cancers, although overall downregulation of miRNA expression is reported as a hallmark of cancer. Modulations of the total pool of cellular miRNA by alteration in genetic and epigenetic factors associated with the biogenesis of miRNA machinery. It also depends on the availability of cellular miRNAs from its store in the organelles which affect tumor development and cancer progression. Here, we have dissected the roles and pathways of various miRNAs during normal cellular and molecular functions as well as during breast cancer progression. Recent research works and prevailing views implicate that there are two major types of miRNAs; (i) intracellular miRNAs and (ii) extracellular miRNAs. Concept, that the functions of intracellular miRNAs are driven by cellular organelles in mammalian cells. Extracellular miRNAs function in cell-cell communication in extracellular spaces and distance cells through circulation. A detailed understanding of organelle driven miRNA function and the precise role of extracellular miRNAs, pre- and post-therapeutic implications of miRNAs in this scenario would open several avenues for further understanding of miRNA function and can be better exploited for the treatment of breast cancers.

Piperlongumine induces apoptosis and G2/M phase arrest in human osteosarcoma cells by regulating ROS/PI3K/Akt pathway

Previous research has reported that piperlongumine exerts antitumor properties on several types of tumor cells. However, its effect on osteosarcoma cells remains unknown. This study aimed to investigate the antitumor effects of piperlongumine on osteosarcoma cells (MG63 and U2OS cells) in vitro and determined the underlying mechanism. Cell viability was measured using MTT assay. Cell apoptosis was assessed via AO/EB staining and flow cytometry apoptosis as well as western blot analysis. Cell cycle distribution was detected by flow cytometric cell cycle and western blot analysis. In our research, we found that piperlongumine induced apoptosis and G2/M phase arrest of MG63 cells. Western blot analysis not only confirmed the above results, but also demonstrated that piperlongumine induced apoptosis of osteosarcoma cells by activating Caspase-9-dependent apoptotic pathway. Furthermore, we also found that piperlongumine significantly induced apoptosis and cell cycle arrest of osteosarcoma cells by regulating ROS/PI3K/Akt signaling pathway. In summary, our findings suggested that piperlongumine inhibited osteosarcoma progression by promoting apoptosis of osteosarcoma cells. In addition, the underlying mechanism demonstrated that piperlongumine produced potent antitumor properties in osteosarcoma cells by regulating ROS/PI3K/Akt signaling pathway.

Dysregulated lncRNA-miRNA-mRNA Network Reveals Patient Survival-Associated Modules and RNA Binding Proteins in Invasive Breast Carcinoma

Breast cancer is the most common cancer in women, but few biomarkers are effective in clinic. Previous studies have shown the important roles of non-coding RNAs in diagnosis, prognosis, and therapy selection for breast cancer and have suggested the significance of integrating molecules at different levels to interpret the mechanism of breast cancer. Here, we collected transcriptome data including long non-coding RNA (lncRNA), microRNA (miRNA), and mRNA for ~1,200 samples, including 1079 invasive breast carcinoma samples and 104 normal samples, from The Cancer Genome Atlas (TCGA) project. We identified differentially expressed lncRNAs, miRNAs, and mRNAs that distinguished invasive carcinoma samples from normal samples. We further constructed an integrated dysregulated network consisting of differentially expressed lncRNAs, miRNAs, and mRNAs and found housekeeping and cancer-related functions. Moreover, 58 RNA binding proteins (RBPs) involved in biological processes that are essential to maintain cell survival were found in the dysregulated network, and 10 were correlated with overall survival. In addition, we identified two modules that stratify patients into high- and low-risk subgroups. The expression patterns of these two modules were significantly different in invasive carcinoma versus normal samples, and some molecules were high-confidence biomarkers of breast cancer. Together, these data demonstrated an important clinical application for improving outcome prediction for invasive breast cancers.

miR-142-3p is a tumor suppressor that inhibits estrogen receptor expression in ER-positive breast cancer

Estrogen receptors (ERs) are involved in the development of many types of malignant tumors, in particular, breast cancer. Among others, ERs affect cell growth, proliferation, and differentiation. The microRNA (miRNA) miR-142-3p has been shown to inhibit carcinogenesis by regulating various cellular processes, including cell cycle progression, cell migration, apoptosis, and invasion. It does so via targeting molecules involved in a range of signaling pathways. We surgically collected 20 ER-positive breast cancer samples, each with matched adjacent normal breast tissue, and measured the expression of miR-142-3p via quantitative real-time polymerase chain reaction (qRT-PCR). Bioinformatics methods, luciferase reporter assay, qRT-PCR, and western blot analysis were used to assess whether miR-142-3p could target ESR1, which encodes the estrogen receptor, in ER-positive breast cancer cells and patient samples. We also restored miRNA expression and performed cell viability, cytotoxicity, and colony formation assays. Western blot analysis and qRT-PCR were used to study the expression of apoptosis and stemness markers. We found that miR-142-3p is downregulated in ER-positive breast cancers. Restoration of miR-142-3p expression in ER-positive breast cancer cells reduced cell viability, induced apoptosis via the intrinsic pathway and decreased both colony formation and the expression of stem cell markers. Bioinformatic analysis predicted miR-142-3p could bind to 3'-untranslated region ESR1 messenger RNA (mRNA). Consistently, we demonstrated that miR-142-3p reduced luciferase activity in ER-positive breast cancer cells, and decreased ESR1 expression in both mRNA and protein levels. The results revealed miR-142-3p and ESR1 expression correlated negatively in ER-positive breast cancer samples. The results suggest miR-142-3p acts as a tumor suppressor via multiple mechanisms. Thus, restoration of miR-142-3p expression, for example, via miRNA replacement therapy, may represent an effective strategy for the treatment of ER-positive breast cancer patients.

HNRNPA2/B1 is upregulated in endocrine-resistant LCC9 breast cancer cells and alters the miRNA transcriptome when overexpressed in MCF-7 cells

MicroRNAs are dysregulated in breast cancer. Heterogeneous Nuclear Ribonucleoprotein A2/B1 (HNRNPA2/B1) is a reader of the N(6)-methyladenosine (m6A) mark in primary-miRNAs (pri-miRNAs) and promotes DROSHA processing to precursor-miRNAs (pre-miRNAs). We examined the expression of writers, readers, and erasers of m6A and report that HNRNPA2/B1 expression is higher in tamoxifen-resistant LCC9 breast cancer cells as compared to parental, tamoxifen-sensitive MCF-7 cells. To examine how increased expression of HNRNPA2/B1 affects miRNA expression, HNRNPA2/B1 was transiently overexpressed (~5.4-fold) in MCF-7 cells for whole genome miRNA profiling (miRNA-seq). 148 and 88 miRNAs were up- and down-regulated, respectively, 48 h after transfection and 177 and 172 up- and down-regulated, respectively, 72 h after transfection. MetaCore Enrichment analysis identified progesterone receptor action and transforming growth factor β (TGFβ) signaling via miRNA in breast cancer as pathways downstream of the upregulated miRNAs and TGFβ signaling via SMADs and Notch signaling as pathways of the downregulated miRNAs. GO biological processes for mRNA targets of HNRNPA2/B1-regulated miRNAs included response to estradiol and cell-substrate adhesion. qPCR confirmed HNRNPA2B1 downregulation of miR-29a-3p, miR-29b-3p, and miR-222 and upregulation of miR-1266-5p, miR-1268a, miR-671-3p. Transient overexpression of HNRNPA2/B1 reduced MCF-7 sensitivity to 4-hydroxytamoxifen and fulvestrant, suggesting a role for HNRNPA2/B1 in endocrine-resistance.

Toll-like receptor 4 and breast cancer: an updated systematic review

Toll-like receptors (TLRs) may play dual roles in human cancers. TLR4 is a key molecule which may participate in both friend and foe roles against breast cancer. This review article collected recent data regarding the mechanisms used by TLR4 in the eradication of breast cancer cells and induction of the tumor cells, and discussed the mechanisms involved in the various functions of TLR4. The literature searches revealed that TLR4 is a key molecule that participates in breast cancer cell eradication or induction of breast cancer development and also transformation of the normal cells. TLR4 eradicates breast cancer cells via recognition of their DAMPs and then induces immune responses. Over-expression of TLR4 and also alterations in its signaling, including association of some intrinsic pathways such as TGF-β signaling and TP53, are the crucial factors to alter TLR4 functions against breast cancer.

Up-regulation of microRNA-497 inhibits the proliferation, migration and invasion but increases the apoptosis of multiple myeloma cells through the MAPK/ERK signaling pathway by targeting Raf-1

Multiple myeloma (MM) is a cancer that occurs in plasma cells, which fall under the category of white blood cells that are in charge of antibody production. According to previous studies, microRNA-497 (miR-497) functions as a tumor suppressor in several types of cancer, including gastric cancer and colorectal cancer. Therefore, the present study aims to investigate the effects of miR-497 on cellular function of human MM cells through the mitogen-activated protein kinase/extracellular signal-regulated kinase (MAPK/ERK) signaling pathway by targeting Raf-1. The differentially expressed genes and miRs in MM, and the relationship between the miR and gene were verified. It was found that Raf-1 was a target gene of miR-497. The data obtained from MM tissues showed increased Raf-1 level and decreased miR-497 level. MM cells were treated with mimic, inhibitor and siRNA in order to evaluate the role of miR-497, Raf-1 and MAPK/ERK in MM. The expression pattern of miR-497, Raf-1, ERK1/2, survivin, B-cell lymphoma-2 (Bcl-2) and BCL2-Associated X (Bax) as well as the extent of ERK1/2 phosphorylation were determined. Retored miR-497 and si-Raf-1 resulted in increases in the Bax expression and cell apoptosis and decreases in the expressions of Raf-1, MEK-2, survivin, Bcl-2, along with the extent of ERK1/2 phosphorylation. In addition, the biological function evaluations of MM cells revealed that miR-497 mimic or si-Raf-1 led to suppression in cell proliferation, invasion and migration. In conclusion, our results have demonstrated that miR-497 targets Raf-1 in order to inhibit the progression of MM by blocking the MAPK/ERK signaling pathway.

LncRNA GACAT3 predicts poor prognosis and promotes cell proliferation in breast cancer through regulation of miR-497/CCND2

Breast cancer is the most common malignancy in women which increases gradually all over the world. LncRNA GACAT3 has been found to be increased in gastric cancer and associated with tumor malignancy. However, whether GACAT3 plays a role in the regulation of breast cancer is not known. In the present study, we found that GACAT3 expression was increased in breast cancer tissues and cells compared with adjacent normal tissues and normal cells. High GACAT3 expression was correlated with the poor prognosis of breast cancer patients. GACAT3 and cyclin D2 (CCND2) contained a binding site of miR-497. miR-497 was decreased in breast cancer tissues and cells compared with adjacent normal tissues and normal cells. Low miR-497 expression was correlated with the poor prognosis of breast cancer patients. In breast cancer tissues, the expression of miR-497 was negatively correlated with GACAT3. Downregulation of GACAT3 increased miR-497 expression. miR-497 mimic reduced the luciferase of GACAT3 and CCND2. Anti-miR-497 reversed the effects of GACAT3 downregulation. We also found that GACAT3 may act as a ceRNA for miR-497, enhancing the expression of CCND2. In conclusion, GACAT3 promotes breast cancer malignancy by sponging miR-497, leading to the enhancement of its endogenous target CCND2. These results suggest that GACAT3/miR-497/CCND2 is a potential therapeutic target and biomarker for breast cancer.

NT21MP negatively regulates paclitaxel-resistant cells by targeting miR‑155‑3p and miR‑155-5p via the CXCR4 pathway in breast cancer

Evidence has shown that microRNAs (miRNAs) are vital in cell growth, migration, and invasion by inhibiting their target genes. A previous study demonstrated that miRNA (miR)-155-3p and miR-155-5p exerted opposite effects on cell proliferation, apoptosis, migration and invasion in breast cancer cell lines. An miRNA microarray was used to show that miR-155-3p was downregulated whereas miR-155-5p was upregulated in paclitaxel-resistant (PR) cells compared with parental breast cancer cells. However, the role of miR-155 in breast cancer cell invasion and metastasis remains to be elucidated. A 21-residue peptide derived from the viral macrophage inflammatory protein II (NT21MP), competes with the ligand of CXC chemokine receptor 4 (CXCR4) and its ligand stromal cell-derived factor-1α, inducing cell apoptosis in breast cancer. The present study aimed to identify the underlying mechanism of action of miR-155-3p/5p and NT21MP in PR breast cancer cells. Quantitative polymerase chain reaction, western blotting, wound-healing, cell cycle and apoptosis assays, and Cell Counting kit-8 assay were used to achieve this goal. The combined overexpression of miR-155-3p with NT21MP decreased the migration and invasion ability and increased the number of apoptotic and arrested cells in the G0/G1 phase transition in vitro. The knockdown of miR-155-5p combined with NT21MP had a similar effect on PR breast cancer cells. Furthermore, the ectopic expression of their target gene myeloid differentiation primary response gene 88 (MYD88) or tumor protein 53-induced nuclear protein 1 (TP53INP1) combined with NT21MP enhanced the sensitivity of the breast cancer cells to paclitaxel. Taken together, these findings suggested that miR-155-3p/5p and their target genes MYD88 and TP53INP1 may serve as novel biomarkers for NT21MP therapy through the CXCR4 pathway for improving sensitivity to paclitaxel in breast cancer.

New emerging roles of microRNAs in breast cancer

BACKGROUND

MicroRNAs constitute a large family of non-coding RNAs, which actively participate in tumorigenesis by regulating a set of mRNAs of distinct signaling pathways. An altered expression of these molecules has been found in different tumorigenic processes of breast cancer, the most common type of cancer in the female population worldwide.

PURPOSE

The objective of this review is to discuss how miRNAs become master regulators in breast tumorigenesis.

METHODS

An integrative review of miRNAs and breast cancer literature from the last 5 years was done on PubMed. We summarize recent works showing that the defects on the biogenesis of miRNAs are associated with different breast cancer characteristics. Then, we show several examples that demonstrate the link between cellular processes regulated by miRNAs and the hallmarks of breast cancer. Finally, we examine the complexity in the regulation of these molecules as they are modulated by other non-coding RNAs and the clinical applications of miRNAs as they could serve as good diagnostic and classification tools.

CONCLUSION

The information presented in this review is important to encourage new directed studies that consider microRNAs as a good tool to improve the diagnostic and treatment alternatives in breast cancer.

Identification of micro-RNA expression profile related to recurrence in women with ESMO low-risk endometrial cancer

Background

Actual European pathological classification of early-stage endometrial cancer (EC) may show insufficient accuracy to precisely stratify recurrence risk, leading to potential over or under treatment. Micro-RNAs are post-transcriptional regulators involved in carcinogenic mechanisms, with some micro-RNA patterns of expression associated with EC characteristics and prognosis. We previously demonstrated that downregulation of micro-RNA-184 was associated with lymph node involvement in low-risk EC (LREC). The aim of this study was to evaluate whether micro-RNA signature in tumor tissues from LREC women can be correlated with the occurrence of recurrences.

Methods

MicroRNA expression was assessed by chip analysis and qRT-PCR in 7 formalin-fixed paraffin-embedded (FFPE) LREC primary tumors from women whose follow up showed recurrences (R+) and in 14 FFPE LREC primary tumors from women whose follow up did not show any recurrence (R−), matched for grade and age. Various statistical analyses, including enrichment analysis and a minimum p-value approach, were performed.

Results

The expression levels of micro-RNAs-184, -497-5p, and -196b-3p were significantly lower in R+ compared to R− women. Women with a micro-RNA-184 fold change < 0.083 were more likely to show recurrence (n = 6; 66%) compared to those with a micro-RNA-184 fold change > 0.083 (n = 1; 8%), p = 0.016. Women with a micro-RNA-196 fold change < 0.56 were more likely to show recurrence (n = 5; 100%) compared to those with a micro-RNA-196 fold change > 0.56 (n = 2; 13%), p = 0.001.

Conclusions

These findings confirm the great interest of micro-RNA-184 as a prognostic tool to improve the management of LREC women.

The estrogen-related receptors in metabolism and cancer: newer insights

The eukaryotic nuclear receptors (NRs) super-family of transcriptional factors include the estrogen-related receptors (ERRs) that have diverse roles in control of cellular energy balance, general metabolism, growth and development, immunity etc. Mouse knock-out models of specific ERR isoforms (ERRα, ERRβ and ERRγ) exhibit defects in several phenotypic traits. Newer findings indicate important roles of ERRs in the regulation of brown adipocyte tissue mitochondrial oxidative functions as well as metabolic control in association with hypoxia-inducible factors during cellular hypoxic state. Genes involved in cardiac metabolism is also influenced by ERRα and ERRγ in association with the co-activators PGC-1α and PGC-1β. On the other hand, ERRs have crucial involvement at the interface of metabolism and diseases such as cancer. Recent findings have implicated ERRα in the progression of tumor and malignancy of the breast, prostate, colon, endometrium etc. In this article, new insights into the regulatory role of ERRs in metabolism and cancer shall be reviewed.

Long non-coding RNA SPRY4-IT1 promotes development of hepatic cellular carcinoma by interacting with ERRα and predicts poor prognosis

Hepatocellular carcinoma (HCC) has become one of the most common leading causes of cancer-related deaths worldwide. This study investigates the role of lncRNA, SPRY4-IT1 in the development of HCC. Quantitative real-time PCR (qRT-PCR) was performed and the results showed that SPRY4-IT1 expression was up-regulated in HCC tissues and high expression of SPRY4-IT1 was associated with poor 5-year overall survival in the HCC patient cohort. Clinicopathological analysis showed that the expression of SPRY4-IT1 was significantly correlated with TNM stage in HCC patients. In vitro CCK-8 assay, colony formation assay, cell invasion and migration assays demonstrated that knock-down of SPRY4-IT1 suppressed cell proliferation, colony formation, cell invasion and migration in HCC cells. Flow cytometric analysis showed that knock-down of SPRY4-IT1 induced cell cycle arrest at G0/G1 phase and induced apoptosis. In addition, knock-down of SPRY4-IT1 also suppressed the mRNA and protein expression of estrogen-related receptor α (ERRα). Similarly, knock-down of ERRα inhibited cell proliferation, colony formation, cell invasion and migration in HCC cells. More importantly, ERRα overexpression antagonized the effects of SPRY4-IT1 knock-down on cell proliferation, colony formation, cell invasion and migration in HCC cells. Taken together, our data highlights the pivotal role of SPRY4-IT1 in the tumorigenesis of HCC.

ERRα protein is stabilized by LSD1 in a demethylation-independent manner

The LSD1 histone demethylase is highly expressed in breast tumors where it constitutes a factor of poor prognosis and promotes traits of cancer aggressiveness such as cell invasiveness. Recent work has shown that the Estrogen-Related Receptor α (ERRα) induces LSD1 to demethylate the Lys 9 of histone H3. This results in the transcriptional activation of a number of common target genes, several of which being involved in cellular invasion. High expression of ERRα protein is also a factor of poor prognosis in breast tumors. Here we show that, independently of its demethylase activities, LSD1 protects ERRα from ubiquitination, resulting in overexpression of the latter protein. Our data also suggests that the elevation of LSD1 mRNA and protein in breast cancer (as compared to normal tissue) may be a key event to increase ERRα protein, independently of its corresponding mRNA.

MicroRNA‑497 inhibits cellular proliferation, migration and invasion of papillary thyroid cancer by directly targeting AKT3

Thyroid cancer is the most common tumor of the endocrine organs. Emerging studies have indicated the critical roles of microRNAs (miRs) in papillary thyroid cancer (PTC) formation and progression through function as tumor suppressors or oncogenes. The present study investigated the expression level and biological roles of miR-497 in PTC and its underlying mechanisms. It was demonstrated that the expression level of miR-497 was reduced in both PTC tissues and cell lines. Enforced expression of miR-497 suppressed PTC cell proliferation, migration and invasion. According to bioinformatics analysis, a luciferase reporter assay, reverse transcription-quantitative polymerase chain reaction and western blotting, RAC-γ serine/threonine-protein kinase (AKT3) was demonstrated to be the direct target gene of miR-497. In addition, AKT3 expression increased in PTC tissues and negatively correlated with miR-497 expression. Furthermore, downregulation of AKT3 also suppressed cell proliferation, migration and invasion of PTC, which had similar roles to miR-497 overexpression in PTC cells. Taken together, these results suggested that this newly identified miR-497/AKT3 signaling pathway may contribute to PTC occurrence and progression. These findings provide novel potential therapeutic targets for the therapy of PTC.

MicroRNA-125a-5p plays a role as a tumor suppressor in lung carcinoma cells by directly targeting STAT3

Increasing evidence supports that the dysregulation of microRNA expression plays an important role in the process of tumor occurrence and development. Studies have found that mir-125a-5p expression was downregulated in a variety of tumors, but the effects and mechanism of mir-125a-5p in lung cancer are still unclear. The aim of this study is to detect the expression of mir-125a-5p in lung cancer tissues and lung cancer cell lines and to explore the effects of mir-125a-5p on the biological characteristics of lung cancer cells; thus, this study aims to provide new methods and new strategies for the treatment of lung cancer. The result from quantitative reverse transcription polymerase chain reaction showed that the expression of miR-125a-5p was significantly lower in lung cancer tissues and lung cancer cell lines (95-D, A549, HCC827, and NCI-H1299) than that in normal tissue adjacent to lung cancer or normal human bronchial epithelial cells. In order to explore the function and mechanism of mir-125a-5p in lung cancer cells, miR-125a-5p mimic or mir-125a-5p inhibitor was transfected into A549 cells. Mir-125a-5p displayed an obvious upregulation in A549 cells transfected with miR-125a-5p and an obvious downregulation in A549 cells transfected with mir-125a-5p inhibitor compared to that in A549 cells transfected with control miRNA. 3-(4,5-Dimethyl-2-thiazolyl)-2,5-diphenyl-2-H-tetrazolium bromide, BrdU staining, flow cytometry, and Transwell assay showed that the upregulation of miR-125a-5p could significantly decrease the cell viability, proliferation, and invasion of lung cancer cells and increase apoptosis of lung cancer cells. The downregulation of miR-125a-5p provided very contrasting results. Computational algorithms predicted that the STAT3 is a target of miR-125a-5p. Here, we validated that miR-125a-5p could directly bind to the 3'-untranslated region of STAT3, and miR-125a-5p overexpression could significantly inhibit the protein expression of STAT3. These results suggested that mir-125a-5p can regulate the expression of STAT3 in lung cancer cells. To further verify whether mir-125a-5p can play a biological role through regulating STAT3, 3-(4,5-dimethyl-2-thiazolyl)-2,5-diphenyl-2-H-tetrazolium bromide, flow cytometry, and Transwell analysis demonstrated that overexpression of STAT3 can reverse the cells' biological effects induced by mir-125a-5p overexpression. Mir-125a-5p downregulated in lung cancer tissue and cell lines can negatively regulate STAT3 protein expression. Taken together, mir-125a-5p inhibited the proliferation and invasion of lung cancer cells and facilitated lung cancer cell apoptosis through suppressing STAT3. Enhancing the expression of miR-125a-5p is expected to benefit the therapy for the patients with lung cancer.