MiR-137 targets estrogen-related receptor alpha and impairs the proliferative and migratory capacity of breast cancer cells

Dynamic interplay of nuclear receptors in tumor cell plasticity and drug resistance: Shifting gears in malignant transformations and applications in cancer therapeutics

Recent advances have brought forth the complex interplay between tumor cell plasticity and its consequential impact on drug resistance and tumor recurrence, both of which are critical determinants of neoplastic progression and therapeutic efficacy. Various forms of tumor cell plasticity, instrumental in facilitating neoplastic cells to develop drug resistance, include epithelial-mesenchymal transition (EMT) alternatively termed epithelial-mesenchymal plasticity, the acquisition of cancer stem cell (CSC) attributes, and transdifferentiation into diverse cell lineages. Nuclear receptors (NRs) are a superfamily of transcription factors (TFs) that play an essential role in regulating a multitude of cellular processes, including cell proliferation, differentiation, and apoptosis. NRs have been implicated to play a critical role in modulating gene expression associated with tumor cell plasticity and drug resistance. This review aims to provide a comprehensive overview of the current understanding of how NRs regulate these key aspects of cancer biology. We discuss the diverse mechanisms through which NRs influence tumor cell plasticity, including EMT, stemness, and metastasis. Further, we explore the intricate relationship between NRs and drug resistance, highlighting the impact of NR signaling on chemotherapy, radiotherapy and targeted therapies. We also discuss the emerging therapeutic strategies targeting NRs to overcome tumor cell plasticity and drug resistance. This review also provides valuable insights into the current clinical trials that involve agonists or antagonists of NRs modulating various aspects of tumor cell plasticity, thereby delineating the potential of NRs as therapeutic targets for improved cancer treatment outcomes.

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.

A feedback loop between lncRNA MALAT1 and DNMT1 promotes triple-negative breast cancer stemness and tumorigenesis

BACKGROUND

The function of long non-coding RNA (lncRNA) MALAT1 in regulating triple-negative breast cancer (TNBC) stemness and tumorigenesis was investigated.

METHODS

Sphere formation and colony formation assays coupled with flow cytometry were employed to evaluate the percentage of CD44high/CD44low cells, and ALDH+ cells were performed to evaluate the stemness. Bisulfite sequencing PCR (BSP) was employed to detect the methylation level of MALAT1. Tumor xenograft experiment was performed to evaluate tumorigenesis in vivo. Finally, dual-luciferase reporter and RIP assays were employed to verify the binding relationship between MALAT1 and miR-137.

RESULTS

Our results revealed that MALAT1 and BCL11A were highly expressed in TNBC, while miR-137 and DNMT1 were lowly expressed. Our results proved that MALAT1 positively regulated BCL11A expression through targeting miR-137. Functional experiments revealed that MALAT1 inhibited DNMT1 expression through acting on the miR-137/BCL11A pathway to enhance TNBC stemness and tumorigenesis. We also found that high MALAT1 expression in TNBC was related to the DNMT1-mediated hypomethylation of MALAT1. As expected, DNMT1 overexpression could remarkably inhibit TNBC stemness and tumorigenesis, which was eliminated by MALAT1 overexpression.

CONCLUSION

MALAT1 downregulated DNMT1 by miR-137/BCL11A pathway to enhance TNBC stemness and tumorigenesis; meanwhile, DNMT1/MALAT1 formed a positive feedback loop to continuously promote TNBC malignant behaviors.

Unraveling the Potential of miRNAs from CSCs as an Emerging Clinical Tool for Breast Cancer Diagnosis and Prognosis

Breast cancer (BC) is the most diagnosed cancer in women and the second most common cancer globally. Significant advances in BC research have led to improved early detection and effective therapies. One of the key challenges in BC is the presence of BC stem cells (BCSCs). This small subpopulation within the tumor possesses unique characteristics, including tumor-initiating capabilities, contributes to treatment resistance, and plays a role in cancer recurrence and metastasis. In recent years, microRNAs (miRNAs) have emerged as potential regulators of BCSCs, which can modulate gene expression and influence cellular processes like BCSCs' self-renewal, differentiation, and tumor-promoting pathways. Understanding the miRNA signatures of BCSCs holds great promise for improving BC diagnosis and prognosis. By targeting BCSCs and their associated miRNAs, researchers aim to develop more effective and personalized treatment strategies that may offer better outcomes for BC patients, minimizing tumor recurrence and metastasis. In conclusion, the investigation of miRNAs as regulators of BCSCs opens new directions for advancing BC research through the use of bioinformatics and the development of innovative therapeutic approaches. This review summarizes the most recent and innovative studies and clinical trials on the role of BCSCs miRNAs as potential tools for early diagnosis, prognosis, and resistance.

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.

MicroRNAs: A Link between Mammary Gland Development and Breast Cancer

Breast cancer is among the most common cancers in women, second to skin cancer. Mammary gland development can influence breast cancer development in later life. Processes such as proliferation, invasion, and migration during mammary gland development can often mirror processes found in breast cancer. MicroRNAs (miRNAs), small, non-coding RNAs, can repress post-transcriptional RNA expression and can regulate up to 80% of all genes. Expression of miRNAs play a key role in mammary gland development, and aberrant expression can initiate or promote breast cancer. Here, we review the role of miRNAs in mammary development and breast cancer, and potential parallel roles. A total of 32 miRNAs were found to be expressed in both mammary gland development and breast cancer. These miRNAs are involved in proliferation, metastasis, invasion, and apoptosis in both processes. Some miRNAs were found to have contradictory roles, possibly due to their ability to target many genes at once. Investigation of miRNAs and their role in mammary gland development may inform about their role in breast cancer. In particular, by studying miRNA in development, mechanisms and potential targets for breast cancer treatment may be elucidated.

Response to neoadjuvant chemotherapy in breast cancer: do microRNAs matter?

BACKGROUND

Conventionally, breast cancer (BC) prognosis and prediction of response to therapy are based on TNM staging, histological and molecular subtype, as well as genetic alterations. The role of various epigenetic factors has been elucidated in carcinogenesis. However, it is still unknown to what extent miRNAs affect the response to neoadjuvant chemotherapy (NACT). This pilot study is focused on evaluating the role of miR-34a, miR-124a, miR-155, miR-137 and miR-373 in response to NACT.

METHODS

That was a prospective study enrolling 34 patients with histologically confirmed BC of II-III stages. The median age of patients was 53 (47-59.8) years old, 70.6% of whom were HR-positive. MiRs levels were measured in the primary tumor before and after NACT. The response to therapy was assessed after surgery using the Miller-Payne scoring system. To establish the role of miRs in modulating response to NACT the Cox model was applied for analysis.

RESULTS

BC demonstrated a great variability of miRs expression before and after NACT with no strong links to tumor stage and molecular subtype. Only miR-124a and miR-373 demonstrated differential expression between malignant and normal breast tissues before and after therapy though these distinctions did not impact response to NACT. Besides miR-124a and miR-137 levels after NACT were found to be dependent on HR status. While miR-124a levels increased (p = 0.021) in the tumor tissue, the expression of miR-137 was downregulated (p = 0.041) after NACT in HR positive BC.

CONCLUSIONS

The study revealed differences in miR-124a and miR-373 expression after NACT in primary BC tissues. Although miRs levels did not impact the response to NACT, we found miR-124a and miR-137 levels to be related to hormonal sensitivity of BC.

The role of noncoding RNAs in pituitary adenoma

Pituitary adenomas (PAs) are common cranial tumors that affect the quality of life in patients. Early detection of PA is beneficial for avoiding clinical complications of this disease and increasing the quality of life. Noncoding RNAs, including long noncoding RNA, miRNA and circRNA, regulate protein expression, mostly by inhibiting the translation process. Studies have shown that dysregulation of noncoding RNAs is associated with PA. Hence understanding the expression pattern of noncoding RNAs can be considered a promising method for developing biomarkers. This article reviews data on the expression pattern of dysregulated noncoding RNAs involved in PA. Possible molecular mechanisms by which the dysregulated noncoding RNA could possibly induce PA are also described.

Expression of estrogen-related receptors in ovarian cancer and impact on survival

PURPOSE

This study further approaches the role of estrogen-related receptors (ERRs) in ovarian cancer. Protein expression of ERRα, ERRβ and ERRγ in ovarian cancer was assessed and was correlated with ovarian cancer markers, steroid hormone receptors and cancer-associated genes. Additionally, we examined to what extent expression of ERRs affects survival of ovarian cancer patients.

METHODS

For this purpose, we established a tissue microarray from 208 ovarian cancer patients and performed immunohistochemical analyses of the mentioned proteins.

RESULTS

ERRα and ERRγ protein could be detected at different levels in more than 90% of all ovarian cancer tissues, whereas expression of ERRβ was observed in 82.2% of the cases. ERRα was found to positively correlate with ovarian cancer marker CEA (p < 0.005) and ERRγ correlated with ERα (p < 0.001). Univariate survival analyses revealed that ERRα expression did not affect overall (OS) or progression-free survival (PFS) of ovarian cancer patients. In contrast, higher expression of ERRβ in serous ovarian cancers was found to lead to a significantly decreased OS (p < 0.05). The strongest impact on survival was exhibited by ERRγ. Lower expression of this receptor in women with serous ovarian cancers indicated significantly increased OS compared to those with higher levels of ERRγ (p < 0.05). Multivariate survival analyses revealed ERRγ as an independent prognostic marker regarding OS of patients with serous ovarian cancer.

CONCLUSION

Our data demonstrating that ERR proteins are frequently expressed in ovarian cancer and high levels of ERRβ and ERRγ significantly decreased OS of serous ovarian cancer patients suggest that these proteins might be interesting therapy targets in this cancer entity.

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.

Rank-preserving biclustering algorithm: a case study on miRNA breast cancer

Effective biomarkers aid in the early diagnosis and monitoring of breast cancer and thus play an important role in the treatment of patients suffering from the disease. Growing evidence indicates that alteration of expression levels of miRNA is one of the principal causes of cancer. We analyze breast cancer miRNA data to discover a list of biclusters as well as breast cancer miRNA biomarkers which can help to understand better this critical disease and take important clinical decisions for treatment and diagnosis. In this paper, we propose a pattern-based parallel biclustering algorithm termed Rank-Preserving Biclustering (RPBic). The key strategy is to identify rank-preserved rows under a subset of columns based on a modified version of all substrings common subsequence (ALCS) framework. To illustrate the effectiveness of the RPBic algorithm, we consider synthetic datasets and show that RPBic outperforms relevant biclustering algorithms in terms of relevance and recovery. For breast cancer data, we identify 68 biclusters and establish that they have strong clinical characteristics among the samples. The differentially co-expressed miRNAs are found to be involved in KEGG cancer related pathways. Moreover, we identify frequency-based biomarkers (hsa-miR-410, hsa-miR-483-5p) and network-based biomarkers (hsa-miR-454, hsa-miR-137) which we validate to have strong connectivity with breast cancer. The source code and the datasets used can be found at http://agnigarh.tezu.ernet.in/~rosy8/Bioinformatics_RPBic_Data.rar . Graphical Abstract.

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.

Immunohistochemical Analysis of PGC-1α and ERRα Expression Reveals Their Clinical Significance in Human Ovarian Cancer

Purpose

Peroxisome proliferator-activated receptor gamma coactivator 1-alpha (PGC-1α) and estrogen-related receptor alpha (ERRα) play a vital role in various human cancers. The purpose of this study was to investigate whether the PGC-1α/ERRα axis could serve as an effective prognostic marker in ovarian cancer (OC).

Patients and Methods

We investigated the expression of both PGC-1α and ERRα in 42 ovarian cancer and 31 noncancerous ovarian samples by immunohistochemistry (IHC). The relationship between the expression of PGC-1α and ERRα in OC and the clinical characteristics of patients was evaluated. In addition, data from the Human Protein Atlas (HPA) database were collected to validate the prognostic significance of PGC-1α and ERRα mRNA expression in OC.

Results

PGC-1α and ERRα showed notably higher expression in OC tissues than in noncancerous tissues (P=0.0059, P=0.002). Moreover, in patients with OC, high ERRα and PGC-1α/ERRα expression significantly correlated with tumor differentiation (P=0.027; P=0.04), lymph node status (P=0.023; P=0.021), CA125 (P=0.036; P=0.021), and HE4 (P=0.021; P=0.05), while high PGC-1α expression was only significantly associated with tumor differentiation (P=0.029). The combined analysis of high PGC-1α and ERRα expression revealed a tendency towards poor cancer-specific survival (P=0.1276).

Conclusion

PGC-1α and ERRα are overexpressed in OC and might be significant prognostic factors for this 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.

DCLK1, a promising colorectal cancer stem cell marker, regulates tumor progression and invasion through miR-137 and miR-15a dependent manner

Cancer stem cells (CSCs) are thought to be a major player in tumor initiation, progression, and metastasis. Targeting CSCs for elimination presents a promising therapeutic strategy; however, this approach will require a stronger understanding of CSC biology and identification of CSC-specific markers. The present study was conducted to examine the correlation between DCLK1 and miR-137 and miR-15a levels in colorectal cancer. A total of 222 samples, including 181 colorectal cancer specimens, 24 adenomatosis, and 17 non-adenomatosis colonic polyps, were stained for DCLK1 expression using immunohistochemistry. Also, expression of miR-137 and miR-15a was assessed in colorectal cancer with high and low DCLK1 expression levels. Most colorectal cancer specimens (76%) showed strong expression of DCLK1, whereas only 21% of adenomatous and none of non-adenomatous colonic polyps showed strong DCLK1 expression. A significant difference in DCLK1 expression was found between colorectal cancer, adenomatous, and non-adenomatous colonic polyps (P < 0.001). Higher expression of DCLK1 was more frequently detected in colorectal cases with larger tumor size (P = 0.03), poor differentiation (P = 0.03), and lymph node involvement (P = 0.04). Comparison of miR-137 and miR-15a in colorectal cancer cases revealed a significant inverse correlation with DCLK1 expression (P = 0.03 and P = 0.04, respectively). DCLK1 may act as a candidate marker for colorectal cancer stem cells. The critical role of DCLK1 in colorectal cancer suggests that it may represent an early diagnostic marker and therapeutic target; however, further investigation is warranted.

PGC-1α and ERRα in patients with endometrial cancer: a translational study for predicting myometrial invasion

BACKGROUND

PGC-1α and ERRα are closely related to tumor formation and progression. However, the mechanism underlying the involvement of PGC-1α/ERRα in regulating invasion and migration in endometrial cancer remains to be explored.

RESULTS

Elevated levels of PGC-1α and ERRα were associated with advanced myometrial invasion, and PGC-1α and Vimentin expression was related to the depth of myometrial invasion in premenopausal endometrial cancer. Silencing of PGC-1α reduced ERRα activation and inhibited epithelial-mesenchymal-transition phenotypes, resulting in significant inhibition of invasion and migration. Overexpression of ERRα led to enhanced PGC-1α expression and increased activity of TFEB, promoting epithelial-mesenchymal-transition in endometrial cancer cells.

CONCLUSIONS

PGC-1α and ERRα induce the epithelial-mesenchymal-transition therefore invasion and migration in endometrial cancer, and may be novel biomarkers to predict the risk of advanced myometrial invasion.

METHODS

PGC-1α, ERRα, and vimentin expression was analyzed in tissue microarrays using immunohistochemistry. PGC-1α and ERRα expression in endometrial cancer cell lines was investigated using quantitative PCR and western blotting analyses after infection with lentivirus-mediated small interfering RNA (siRNA) targeting PGC-1α (siRNA-PGC-1α) or overexpressing ERRα. E-cadherin and vimentin levels were determined using western blotting and cell immunouorescence analyses. Cell migration and invasiveness were evaluated using scratch and trans-well chamber assays.

Potential miRNAs for miRNA-Based Therapeutics in Breast Cancer

MicroRNAs (miRNAs) are small non-coding RNAs that can post-transcriptionally regulate the genes involved in critical cellular processes. The aberrant expressions of oncogenic or tumor suppressor miRNAs have been associated with cancer progression and malignancies. This resulted in the dysregulation of signaling pathways involved in cell proliferation, apoptosis and survival, metastasis, cancer recurrence and chemoresistance. In this review, we will first (i) provide an overview of the miRNA biogenesis pathways, and in vitro and in vivo models for research, (ii) summarize the most recent findings on the roles of microRNAs (miRNAs) that could potentially be used for miRNA-based therapy in the treatment of breast cancer and (iii) discuss the various therapeutic applications.

Predictive role of single nucleotide polymorphism (rs11614913) in the development of breast cancer in Pakistani population

Aim: miRNAs play an important role in breast cancer (BC). Variations in miRNAs influence their maturation, expression and consequently regulation of their target genes. Materials & methods: In this study, single nucleotide polymorphism rs11614913 was genotyped in BC patients (n = 300) and 230 controls by employing tetra primer amplification refractory mutation system PCR and Sanger sequencing (Macrogen Korea). Results: A significant difference was observed in the genotypes through co-dominant (χ².#x00A0;= 42.03; p < 0.0001), additive (odds ratio [OR] = 0.6441 [0.4887-0.8490, 95% confidence interval]; p < 0.0019), dominant (OR = 0.3996 [0.2809-0.5686], p < 0.0001) and recessive (OR = 0.2993 [0.1220-0.7347], p < 0.009) statistical models showed decreased risk association of C allele with BC. Conclusion: Females having CT genotype are at higher risk of BC as compared with those having CC genotype.

MicroRNA-137 Inhibits Cancer Progression by Targeting Del-1 in Triple-Negative Breast Cancer Cells

MicroRNAs (miRNAs) can be used to target a variety of human malignancy by targeting their oncogenes or tumor suppressor genes. The developmental endothelial locus-1 (Del-1) might be under miRNA regulation. This study investigated microRNA-137 (miR-137) function and Del-1 expression in triple-negative breast cancer (TNBC) cells and tissues. Del-1 mRNA and miRNA-137 levels were determined via qRT-PCR in breast cancer cells (MDA-MB-231, MCF7, SK-BR3, and T-47D) and tissues from 30 patients with TNBC. The effects of miR-137 on cell proliferation, migration, and invasion were determined using MTT assays, wound healing, and Matrigel transwell assays. The luciferase reporter assay revealed direct binding of miR-137 to the 3'-UTR of Del-1. miR-137 inhibited cell proliferation, migration, and invasion of MDA-MB-231 cells. Among the 30 TNBC specimens, miR-137 was downregulated and Del-1 level in plasma was significantly elevated relative to normal controls. It is concluded that miR-137 regulates Del-1 expression in TNBC by directly binding to the Del-1 gene and cancer progression. The results implicate miR-137 as a new therapeutic biomarker for patients with TNBC.

miR-137 alleviates doxorubicin resistance in breast cancer through inhibition of epithelial-mesenchymal transition by targeting DUSP4

Acquired resistance to chemotherapy is a major obstacle in breast cancer (BC) treatment. Accumulated evidence has uncovered that microRNAs (miRNAs) are vital regulators of chemoresistance in cancer. Growing studies reveal that miR-137 acts as a suppressor in tumor progression. However, it remains obscure the role of miR-137 in modulating the sensitivity of BC cells to doxorubicin (DOX). In this study, we demonstrate that miR-137 exerts a significant effect on repressing the development of chemoresistance of BC cells in response to DOX via attenuating epithelial-mesenchymal transition (EMT) of tumor cells in vitro and in vivo. MiR-137 overexpression dramatically elevated the sensitivity of BC cells to DOX as well as impaired the DOX-promoted EMT of tumor cells. Mechanistically, miR-137 directly targeted dual-specificity phosphatase 4 (DUSP4) to impact on the EMT and chemoresistance of BC cells upon DOX treatment. Consistently, decreased DUSP4 efficiently enhanced the sensitivity of BC cells to DOX while overexpressed DUSP4 significantly diminished the beneficial effect of miR-137 on BC cells chemoresistance. Moreover, the increased miR-137 heightened the sensitivity of BC cells-derived tumors to DOX through targeting DUSP4 in vivo. Together, our results provide a novel insight into the DOX resistance of BC cells and miR-137 may serve as a new promising therapeutic target for overcoming chemoresistance in BC.

Extensive transcriptional responses are co-ordinated by microRNAs as revealed by Exon-Intron Split Analysis (EISA)

Epithelial-mesenchymal transition (EMT) has been a subject of intense scrutiny as it facilitates metastasis and alters drug sensitivity. Although EMT-regulatory roles for numerous miRNAs and transcription factors are known, their functions can be difficult to disentangle, in part due to the difficulty in identifying direct miRNA targets from complex datasets and in deciding how to incorporate 'indirect' miRNA effects that may, or may not, represent biologically relevant information. To better understand how miRNAs exert effects throughout the transcriptome during EMT, we employed Exon-Intron Split Analysis (EISA), a bioinformatic technique that separates transcriptional and post-transcriptional effects through the separate analysis of RNA-Seq reads mapping to exons and introns. We find that in response to the manipulation of miRNAs, a major effect on gene expression is transcriptional. We also find extensive co-ordination of transcriptional and post-transcriptional regulatory mechanisms during both EMT and mesenchymal to epithelial transition (MET) in response to TGF-β or miR-200c respectively. The prominent transcriptional influence of miRNAs was also observed in other datasets where miRNA levels were perturbed. This work cautions against a narrow approach that is limited to the analysis of direct targets, and demonstrates the utility of EISA to examine complex regulatory networks involving both transcriptional and post-transcriptional mechanisms.

MiR-137 inhibits cell proliferation in acute lymphoblastic leukemia by targeting JARID1B

AIM

This study aimed to investigate the possible functions of interaction between JARID1B and miR-137 in ALL.

METHODS

The levels of H3K4me3 and H3K4me2 and the expression of JARID1B and miR-137 were analyzed in six ALL cell lines and 30 ALL patients. The effects of miR-137 and JARID1B on cell proliferation and apoptosis were investigated by silencing or promoting the respective genes. The interaction between miR-137 and JARID1B was confirmed by double-luciferase report assay.

RESULTS

The histone H3K4 expressions and miR-137 expression were lower in 30 ALL patients and in six ALL cell lines, while the expression of JARID1B was elevated. A negative correlation was observed between JARID1B and miR-137. Over-expression of miR-137 led to decreasing cell proliferation and increasing apoptosis in MOLT-4 and BALL-1 cells. MiR-137 inhibitor up-regulated JARID1B in these two cell lines, while promoted proliferation in BALL-1 cells only. Dual-luciferase report assay suggested that JARID1B was a direct target of miR-137 in ALL cell lines.

CONCLUSIONS

The expression of miR-137 was declined in ALL, and JARID1B was directly repressed by miR-137. Aberrant JARID1B expression could result in abnormal histone methylation, which might be one cause of ALL.

Overexpression of mircoRNA-137 inhibits cervical cancer cell invasion, migration and epithelial-mesenchymal transition by suppressing the TGF-β/smad pathway via binding to GREM1

Background

Accumulating evidence has highlighted the tumor suppressive roles of microRNA (miRNAs) in cervical cancer (CC). In the present study, we aim to delineate the functional relevance of microRNA-137 (miR-137) in influencing epithelial-mesenchymal transition (EMT), and other CC cell biological activities via the TGF-β/smad pathway by binding to GREM1.

Methods

Microarray analysis was initially adopted to predict the differentially expressed genes and the miRNAs related to CC, followed by the measurement of the expression patterns of GREM1, EMT-related factors in the CC tissues and the adjacent tissues. Dual luciferase reporter gene assay was conducted to determine the relationship between miR-137 and GREM1. Gain-of- and loss-of-function experiments were conducted to characterize the effects of miR-137 and GREM1 on the colony formation, proliferation, apoptosis, migration, and invasion of CC cells in vitro, and the tumorigenicity of the CC cells in nude mice. The TGF-β/smad pathway was subsequently blocked with si-TGF-β to investigate its involvement.

Results

Reduced miR-137 expression and increased GREM1 expression were predicted in CC, which was subsequently observed in the CC tissues and cells. Notably, GREM1 was a target gene of miR-137. The overexpressed miR-137 was found to inhibit EMT, cell proliferation, colony formation, invasion, migration and tumorigenesis in nude mice. In addition, miR-137 was noted to inhibit the activation of the TGF-β/smad pathway by binding to GREM1. The silencing of TGF-β1 was shown to reverse the effects induced by downregulated expression of miR-137.

Conclusions

This study suggests that upregulated miR-137 suppresses the tumor progression in CC via blocking the TGF-β/smad pathway by binding to and negatively regulating GREM1.

Differential microRNA expression profiles determined by next-generation sequencing in three fulvestrant-resistant human breast cancer cell lines

Fulvestrant resistance is a major clinical issue in the treatment of endocrine-based breast cancer. MicroRNAs (miRNAs) are known to serve an important role in tumor chemoresistance. In the present study, the association between miRNA expression profiles and fulvestrant resistance was investigated in human breast cancer cell lines. Three fulvestrant-resistant breast cancer cell lines, namely MCF-7-CC, MCF-7-TT and MCF-7-21, were established using the human breast cancer cell line MCF-7 as the parental cell line and fulvestrant as the screening drug in vitro. Next-generation sequencing was used to determine the miRNA expression profiles in these cell lines. Subsequently, Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway analyses were performed to determine the biological functions of differentially expressed miRNAs. In total, 1,536 miRNAs were detected in all the samples, including 1,240 known miRNAs and 296 predicted miRNAs. It was observed that the differential miRNA expression profiles varied among the three fulvestrant-resistant cell lines (MCF-7-CC, MCF-7-TT and MCF-7-21), and certain differentially expressed miRNAs were only detected in one or two of the cell lines. A total of 257 miRNAs that were differentially expressed between MCF-7-CC and MCF-7 cells were detected, among which 69 miRNAs were upregulated and 188 miRNAs were downregulated. In addition, 270 miRNAs with significantly different expression between MCF-7-TT and MCF-7 cells were observed, including 180 upregulated and 90 downregulated miRNAs. Between MCF-7-21 and MCF-7 cells, a total of 227 miRNAs were differentially expressed, among which 52 miRNAs were upregulated and 175 miRNAs were downregulated. The miRNAs that were differentially expressed in the three fulvestrant-resistant cell lines as compared with the parental MCF-7 cell line were primarily involved in the following biological processes: Biological regulation, extracellular matrix-receptor interaction, the Notch signaling pathway and focal adhesion. Taken together, the results suggested that miR-143, miR-145, miR-137, miR-424 and miR-21 may serve important roles in fulvestrant resistance in breast cancer. The study findings may provide a basis for further research on the treatment of fulvestrant-resistant breast cancer.

Functional polymorphism within miR-23a∼27a∼24-2 cluster confers clinical outcome of breast cancer in Pakistani cohort

AIM

MicroRNAs (miRNAs) are small regulatory RNA molecules that control gene activity by base pairing with target messenger RNA leading to their cleavage or translational repression. Previous studies show an involvement of miRNAs in various diseases including cancer. Members of the Mir-23a cluster (MIR23A, MIR24-2 and MIR27A) are involved in breast cancer (BC).

METHODS

In the present study, miR-23a/24-2/27a cluster was screened for genetic mutation in BC patients.

RESULTS

Heterozygous (A/G allele) as well as homozygous (G/G allele) variants were found in mir-27a gene in screened BC patients. RNA structural analysis revealed that the single nucleotide polymorphism (SNP) effects the size of the terminal loop in the precursor miRNA (pre-miRNA).

CONCLUSION

The altered (G allele) hairpin structure observed was two bases longer than the reference (A allele) hairpin.

Downregulated NOX4 underlies a novel inhibitory role of microRNA-137 in prostate cancer

Prostate cancer is the second highest caused by cancer-related death among males. microRNAs (miRs) have been reported to participate in carcinogenesis, yet their roles in prostate cancer are rarely studied or investigated. Therefore, the present study attempted to explore the effect of miR-137 in prostate cancer via regulating NADPH oxidase 4 (NOX4). Initially, microarray analysis was performed to obtain prostate cancer-related differentially expressed genes and miRs that regulated NOX4, followed by detecting the expression of miR-137 and NOX4 and its target relationship. Moreover, PC-3 cells were transfected with small interfering RNA (siNOX4) and miR-137 mimic for exploring the effect of miR-137 on glycolysis, cell proliferation, and apoptosis in prostate cancer by evaluating lactate production, glucose uptake, adenosine triphosphate (ATP) production, viability rate, and expression of cleaved caspases 3, 8, and 9, cytochrome c, cleaved poly ADP ribose polymerase (PARP), Bax, and Bcl-2. miR-137 was vital to prostate cancer progression via regulating NOX4. Besides, miR-137 expressed poorly while NOX4 expressed highly in prostate cancer. NOX4 was the target gene of miR-137. Additionally, overexpression of miR-137 and silencing of NOX4 were observed to decrease NOX4 and Bcl-2 protein expression, but increase cleaved caspases 3, 8, and 9, cytochrome c, cleaved-PARP, and Bax protein expression. Furthermore, miR-137 overexpression and NOX4 silencing contributed to decreased lactate production, glucose uptake, ATP production, and cell proliferation, but increased apoptosis rate. Collectively, the present study showed that miR-137 repressed glycolysis in prostate cancer through knockdown of NOX4, which might be a potential theoretical target for prostate cancer treatment.

ERRα as a Bridge Between Transcription and Function: Role in Liver Metabolism and Disease

As transcriptional factors, nuclear receptors (NRs) function as major regulators of gene expression. In particular, dysregulation of NR activity has been shown to significantly alter metabolic homeostasis in various contexts leading to metabolic disorders and cancers. The orphan estrogen-related receptor (ERR) subfamily of NRs, comprised of ERRα, ERRβ, and ERRγ, for which a natural ligand has yet to be identified, are known as central regulators of energy metabolism. If AMP-activated protein kinase (AMPK) and mechanistic target of rapamycin (mTOR) can be viewed as sensors of the metabolic needs of a cell and responding acutely via post-translational control of proteins, then the ERRs can be regarded as downstream effectors of metabolism via transcriptional regulation of genes for a long-term and sustained adaptive response. In this review, we will focus on recent findings centered on the transcriptional roles played by ERRα in hepatocytes. Modulation of ERRα activity in both in vitro and in vivo models via genetic or pharmacological manipulation coupled with chromatin-immunoprecipitation (ChIP)-on-chip and ChIP-sequencing (ChIP-seq) studies have been fundamental in delineating the direct roles of ERRα in the control of hepatic gene expression. These studies have identified crucial roles for ERRα in lipid and carbohydrate metabolism as well as in mitochondrial function under both physiological and pathological conditions. The regulation of ERRα expression and activity via ligand-independent modes of action including coregulator binding, post-translational modifications (PTMs) and control of protein stability will be discussed in the context that may serve as valuable tools to modulate ERRα function as new therapeutic avenues for the treatment of hepatic metabolic dysfunction and related diseases.

Key regulator of cellular metabolism, estrogen-related receptor α, a new therapeutic target in endocrine-related gynecological tumor

The estrogen-related receptor α (ERRα), is an orphan transcription factor. Recently, many studies have reported its regulatory mechanisms and transcriptional targets after identification. Therefore, it may be eligible to join the rank of other nuclear receptors that control almost all aspects of cell metabolism. Cellular metabolism reprogramming plays a key role in fueling malignant change. The purpose of this review was to demonstrate that the ERRα plays an important role in the association between gynecological endocrine-related tumors and energy metabolism. Furthermore, regulation of ERRα may represent a promising strategy to induce cellular metabolic vulnerability of cancer from different origins. Thus, a comprehensive understanding of current treatment strategies may be achieved.

FSTL1 enhances chemoresistance and maintains stemness in breast cancer cells via integrin β3/Wnt signaling under miR-137 regulation

FSTL1 is a protein coding gene associated with cell signaling pathway regulation and the progression of a variety of disorders. In this study, we hypothesized that FSTL1 increases oncogenesis in breast cancer by enhancing stemness and chemoresistance. RT-PCR and IHC revealed significantly higher FSTL1 mRNA and protein levels in TNBC than in non-TNBC specimens and in breast cancer cell lines. We then found that FSTL1 levels were significantly increased in chemoresistant cells. LIVE/DEAD, MTT cell viability and colony formation assays did in fact demonstrate that FSTL1 is required for CDDP and DOX chemoresistance in breast cancer cell lines. FSTL1 overexpression caused significant elevation of stem cell biomarkers, as well as breast cancer cell proliferation. To determine whether the Wnt/β-catenin signaling pathway is involved in the observed effects of FSTL1, we assessed levels of pathway target. TOP/FOP flash, colony formation, and tumor sphere formation assays indicated that FSTL1 activates Wnt/β-catenin signaling through integrin β3. We then sought to identify a microRNA (miRNA) that regulates FSTL1 activity. Luciferase assays demonstrated that miR-137 reduces FSTL1 mRNA and protein levels. Ultimately, our findings indicate that there is an miR-137/FSTL1/integrin β3/Wnt/β-catenin signaling axis in breast cancer cells that regulates stemness and chemoresistance.

ISO, via Upregulating MiR-137 Transcription, Inhibits GSK3β-HSP70-MMP-2 Axis, Resulting in Attenuating Urothelial Cancer Invasion

Our most recent studies demonstrate that miR-137 is downregulated in human bladder cancer (BC) tissues, while treatment of human BC cells with isorhapontigenin (ISO) elevates miR-137 abundance. Since ISO showed a strong inhibition of invasive BC formation in the N-butyl-N-(4-hydroxybutyl) nitrosamine (BBN)-induced invasive BC mouse model, the elucidation of a potential biological effect of miR-137 on antagonizing BC invasion and molecular mechanisms underlying ISO upregulation of miR-137 are very important. Here we discovered that ectopic expression of miR-137 led to specific inhibition of BC invasion in human high-grade BC T24T and UMUC3 cells, while miR-137 deletion promoted the invasion of both cells, indicating the inhibitory effect of miR-137 on human BC invasion. Mechanistic studies revealed that ISO treatment induced miR-137 transcription by promoting c-Jun phosphorylation and, in turn, abolishing matrix metalloproteinase-2 (MMP-2) abundance and invasion in BC cells. Moreover, miR-137 was able to directly bind to the 3' UTR of Glycogen synthase kinase-3β (GSK3β) mRNA and inhibit GSK3β protein translation, consequently leading to a reduction of heat shock protein-70 (HSP70) translation via targeting the mTOR/S6 axis. Collectively, our studies discover an unknown function of miR-137, directly targeting the 3' UTR of GSK3β mRNA and, thereby, inhibiting GSK3β protein translation, mTOR/S6 activation, and HSP70 protein translation and, consequently, attenuating HSP70-mediated MMP-2 expression and invasion in human BC cells. These novel discoveries provide a deep insight into understanding the biomedical significance of miR-137 downregulation in invasive human BCs and the anti-cancer effect of ISO treatment on mouse invasive BC formation.

The down-regulation of microRNA-137 contributes to the up-regulation of retinoblastoma cell proliferation and invasion by regulating COX-2/PGE2 signaling

MicroRNA-137 (miR-137) plays an important role in the development and progression of many types of human cancers; however, the role of miR-137 in retinoblastoma (RB) remains unclear. In this study, we aimed to investigate the functional significance and molecular mechanisms of miR-137 in RB. We reported that miR-137 was frequently down-regulated in RB tissues and cell lines. The overexpression of miR-137 inhibited RB cell proliferation and invasion, while the suppression of miR-137 promoted RB cell proliferation and invasion. Bioinformatic analysis predicted that cyclooxygenase-2 (COX-2) was a potential target gene of miR-137, which was validated by a dual-luciferase reporter assay. Moreover, our results showed that miR-137 negatively regulated the expression of COX-2 and the production of prostaglandin E2 (PGE2) in RB cells. The knockdown of COX-2 suppressed the proliferation and invasion of RB cells as well as the production of PGE2. The overexpression of COX-2 significantly reversed the inhibitory effect of miR-137 overexpression on RB cell proliferation and invasion. Taken together, these results suggest that miR-137 suppresses the proliferation and invasion of RB cells by targeting COX-2/PGE2. Our study reveals a tumor suppressive role of miR-137 in the progression of RB and suggests miR-137 as a potentially effective therapeutic target for the treatment of RB.

miR-137 suppresses proliferation, migration and invasion of colon cancer cell lines by targeting TCF4

Colorectal cancer is cancer of the colon or rectum and is the third most prevalent form of cancer. Currently, there are several shortcomings in the prognosis and early detection of colon cancer. The present study aims to address questions pertaining to the role of microRNA (miR)-137 in colon cancer progression and the mode of regulation. The endogenous and over-expressed levels of miR-137 in three colon cancer cell lines were assessed by reverse transcription-quantitative polymerase chain reaction (RT-qPCR). The MTT assay was used to assess cell proliferation. Cell migration and invasion assays were assessed using Transwell apparatus and Matrigel invasion chambers. The potential targets of miR-150 were predicted using TargetScan software, and one of the best scoring targets, transcription factor 4 (TCF4), was experimentally validated using western blot analysis and RT-qPCR. It was found that that miR-137 is expressed at extremely low levels in COLO205, HCT116 and SW480 cell lines. Cell proliferation, migration and invasion were inhibited subsequent to transfection of the colon cancer cell lines with miR-137. Using bioinformatics analysis, the best scoring putative targets were identified. One such target, TCF4, was experimentally validated, and it was shown that overexpression of miR-137 suppresses TCF4 in all three colon cancer cell lines. In conclusion, it was shown that miR-137 inhibits cell proliferation, migration and invasion in colon cancer cell lines by negatively regulating the expression of TCF4.

MiR-137 suppresses tumor growth and metastasis in clear cell renal cell carcinoma

BACKGROUND

The most frequent type of renal cell carcinoma is called clear-cell renal cell carcinoma (ccRCC) which is associated with a poor prognosis. It has been observed that miR-137 is aberrantly expressed in many different kinds of human malignancies including ccRCC. This research aims to examine the role of miR-137 in ccRCC.

METHODS

Quantitative RT-PCR (qRT-PCR) was applied to measure miR-137 expression in ccRCC and adjacent noncancerous tissue. Gene expression was determined by western blot. Cell Counting Kit-8 (CCK-8) assay, flow cytometry and Transwell assay were used to determine the effects of miR-137 on cell growth, apoptosis and invasion, respectively. Moreover, xenograft and pulmonary metastasis animal models were established to investigate the role of miR-137 in vivo.

RESULTS

Our findings show that there was significant downregulation of miR-137 in ccRCC tissue relative to corresponding non-cancerous tissue. Ectopic miR-137 expression in ccRCC cells led to suppression of cell growth and invasion, as well as apoptosis induction. In contrast, knockdown of miR-137 enhances proliferation and invasion, inhibits apoptosis. It also confirms that miR-137 plays a tumor supressor role in vivo. Mechanically, miR-137 directly targets the 3'-UTR of RLIP76 which is an established oncogene in ccRCC.

CONCLUSION

MiR-137 serves as a tumor suppressor, which can be considered a potential therapeutic target in ccRCC.

Aberrant microRNA-137 promoter methylation is associated with lymph node metastasis and poor clinical outcomes in non-small cell lung cancer

MicroRNA-137 (miR-137) functions as a tumor suppressor and is silenced by aberrant promoter methylation. Previous studies have demonstrated that miR-137 is downregulated in lung cancer. The purpose of the present study was to investigate miR-137 promoter methylation and to assess its prognostic value in non-small cell lung cancer (NSCLC). The expression of miR-137 was analyzed inhuman lung cancer A549 and H1299 cells and normal bronchial epithelial BEAS-2B cells, 10 paired formalin-fixed paraffin-embedded lung cancer and normal tissue samples, and 56 archived paraffin-embedded lung cancer tissues. Quantitative methylation-specific polymerase chain reaction analysis was used to assess the miR-137 methylation status. The associations between miR-137 promoter methylation and the clinicopathological features and prognosis of patients with NSCLC (n=56) were analyzed using analysis of variance. miR-137 was markedly downregulated in lung cancer cells and lung cancer tissue specimens compared with expression in BEAS-2B cells and matched adjacent normal lung tissues. A significant negative correlation between miR-137 expression and miR-137 promoter methylation was observed in human lung cancer tissues (r=-0.343; P=0.01). Smoking, lymph node metastasis and advanced clinical stage were associated with significantly lower expression of miR-137 in variance analysis. High levels of miR-137 promoter methylation were associated with a significantly poorer disease-free survival rate (P=0.034), but were not associated with overall survival, in Kaplan-Meier analysis and univariate analysis. In conclusion, the results of the present study indicated that miR-137 is downregulated and that its promoter is aberrantly methylated in lung cancer, and that high levels of miR-137 promoter methylation may have prognostic value for poor disease-free survival.

A comprehensive review of the genetic and biological evidence supports a role for MicroRNA-137 in the etiology of schizophrenia

Since it was first associated with schizophrenia (SCZ) in a 2011 genome-wide association study (GWAS), there have been over 100 publications focused on MIR137, the gene encoding microRNA-137. These studies have examined everything from its fundamental role in the development of mice, flies, and fish to the intriguing enrichment of its target gene network in SCZ. Indeed, much of the excitement surrounding MIR137 is due to the distinct possibility that it could regulate a gene network involved in SCZ etiology, a disease which we now recognize is highly polygenic. Here we comprehensively review, to the best of our ability, all published genetic and biological evidence that could support or refute a role for MIR137 in the etiology of SCZ. Through a careful consideration of the literature, we conclude that the data gathered to date continues to strongly support the involvement of MIR137 and its target gene network in neuropsychiatric traits, including SCZ risk. There remain, however, more unanswered than answered questions regarding the mechanisms linking MIR137 genetic variation with behavior. These questions need answers before we can determine whether there are opportunities for diagnostic or therapeutic interventions based on MIR137. We conclude with a number of suggestions for future research on MIR137 that could help to provide answers and hope for a greater understanding of this devastating disorder.

Epigenetic silencing of miR-137 contributes to early colorectal carcinogenesis by impaired Aurora-A inhibition

MicorRNA-137 is silenced in human colorectal cancer tissues and colon polyps. Our study showed that the decreased expression of miR-137 is significantly different in various types of polyp which maintain different potentials to lead to CRC development. The expression of miR-137 gradually decreases during the process of colorectal carcinogenesis. Receiver operating characteristic curve (ROC) analysis indicates that the loss of miR-137 expression in colon polyps can serve as a biomarker to predict the predisposition of colorectal carcinogenesis. By cell model and xenograft animal model, the enforced expression of miR-137 in colorectal cancer cells can inhibit cell proliferation and tumor formation, induce G2/M arrest, and lead to apoptosis. The expression pattern of miR-137 and Aurora-A or PTGS2 is negatively correlated in human colorectal cancer tissues and colon polyps. Those effects induced by overexpressed miR-137 can be rescued by the overexpression of Aurora-A. In summary, our study suggests that the loss of miR-137 expression in colon polyps can serve as a biomarker to predict the tendency toward to CRC formation through the impaired inhibitory effect of Aurora-A. The investigation of the regulatory mechanism of miR-137-mediated Aurora-A inhibition may shed new light on the early prognosis of cancer therapy for CRC in the future.

High expression of estrogen-related receptor α is significantly associated with poor prognosis in patients with colorectal cancer

Colorectal cancer (CRC) is one of the most common types of malignancy with high morbidity and mortality rates worldwide. This biologically heterogeneous disease results in diverse therapeutic responses, thus, novel prognostic biomarkers are required to improve CRC treatment. Estrogen-related receptor α (ERRα) is a nuclear orphan receptor, which is associated with estrogen receptor α. The present study aimed to investigate the expression of ERRα in patients with CRC, and explore the association between ERRα expression and clinicopathological factors, local recurrence and prognosis. In the present study, ERRα expression was detected in 15 fresh CRC tissues using quantitative real-time polymerase chain reaction (RT-qPCR) and in 128 paraffin-embedded CRC tissues using immunohistochemistry. The associations between ERRα expression and prognosis of CRC patients were evaluated by univariate, and multivariate (Cox proportional hazards model) analysis. RT-qPCR demonstrated that the mRNA expression of ERRα in CRC tissues was significantly higher compared with that in matched normal tissues. Immunohistochemistry revealed that ERRα high expression was detected in the nuclei of cancer cells from 39.1% (50/128) of CRC tissues. ERRα expression based on immunohistochemical staining was significantly associated with tumor differentiation, tumor invasion, lymph node status and Dukes stage (all P<0.05). Furthermore, patients with high ERRα expression were significantly associated with an increased risk of recurrence and poor prognosis, compared with patients with low ERRα expression. ERRα expression was identified as an independent prognostic factor for patients with CRC. In conclusion, ERRα serves important roles in the progression of CRC and is a potential prognostic factor for patients with CRC.

miR‑137 decreases proliferation, migration and invasion in rheumatoid arthritis fibroblast‑like synoviocytes

MicroRNA-137 (miR-137) is involved in cell proliferation, migration, invasion and apoptosis in a variety of cells. However, the role of miR‑137 in rheumatoid arthritis (RA) remains unclear. The present study aimed to identify the biological roles of miR‑137 in RA. The expression of miR‑137 in RA fibroblast‑like synoviocytes (RA‑FLS) and in normal control FLS was detected by reverse transcription‑quantitative polymerase chain reaction (RT‑qPCR). The effects of miR‑137 on RA‑FLS proliferation, migration and invasion were also determined using MTT, wound healing and Transwell invasion assays, respectively. The effects of miR‑137 on inflammatory cytokine expression in RA‑FLS were assessed by ELISA. Bioinformatics databases (TargetScan and miRanda), luciferase reporter assays, RT‑qPCR and western blotting assays were conducted to identify potential target genes. miR‑137 expression was decreased in RA‑FLS compared with expression in normal control FLS. Overexpression of miR‑137 resulted in a significant reduction in RA‑FLS proliferation, migration and invasion, and decreased the expression of inflammatory cytokines of RA‑FLS. In addition, bioinformatics analysis and luciferase reporter assays indicated that miR‑137 may target the 3'‑untranslated region of C‑X‑C motif chemokine ligand 12 (CXCL12), which was confirmed by RT‑qPCR and western blot analyses. These results further demonstrated that miR‑137may serve an inhibitory role in RA by targeting CXCL12 expression, and miR‑137 may be a potential target for the treatment of RA.

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.

A New Network-Based Strategy for Predicting the Potential miRNA-mRNA Interactions in Tumorigenesis

MicroRNA (miRNA) plays an important role in the degradation and inhibition of mRNAs and is a kind of essential drug targets for cancer therapy. To facilitate the clinical cancer research, we proposed a network-based strategy to identify the cancer-related miRNAs and to predict their targeted genes based on the gene expression profiles. The strategy was validated by using the data sets of acute myeloid leukemia (AML), breast invasive carcinoma (BRCA), and kidney renal clear cell carcinoma (KIRC). The results showed that in the top 20 miRNAs ranked by their degrees, 90.0% (18/20), 70.0% (14/20), and 70.0% (14/20) miRNAs were found to be associated with the cancers for AML, BRCA, and KIRC, respectively. The KEGG pathways and GO terms enriched with the genes that were predicted as the targets of the cancer-related miRNAs were significantly associated with the biological processes of cancers. In addition, several genes, which were predicted to be regulated by more than three miRNAs, were identified to be the potential drug targets annotated by using the human protein atlas database. Our results demonstrated that the proposed strategy can be helpful for predicting the miRNA-mRNA interactions in tumorigenesis and identifying the cancer-related miRNAs as the potential drug targets.

Emerging functional roles of nuclear receptors in breast cancer

Nuclear receptors (NRs) have been targets of intensive drug development for decades due to their roles as key regulators of multiple developmental, physiological and disease processes. In breast cancer, expression of the estrogen and progesterone receptor remains clinically important in predicting prognosis and determining therapeutic strategies. More recently, there is growing evidence supporting the involvement of multiple nuclear receptors other than the estrogen and progesterone receptors, in the regulation of various processes important to the initiation and progression of breast cancer. We review new insights into the mechanisms of action of NRs made possible by recent advances in genomic technologies and focus on the emerging functional roles of NRs in breast cancer biology, including their involvement in circadian regulation, metabolic reprogramming and breast cancer migration and metastasis.

miR-137 inhibits the proliferation of human non-small cell lung cancer cells by targeting SRC3

Non-small cell lung cancer (NSCLC) is the most common type of lung cancer. The results of the present study demonstrate that high expression of microRNA (miR)-137 and low expression of steroid receptor coactivator-3 (SRC3) had a significant negative correlation in 40 NSCLC tissue samples. In addition, cell colony formation and proliferation was significantly reduced in miR-137-transfected A549 and NCI-H838 cells compared with scramble-transfected NSCLC cell lines. miR-137 was identified to induce G₁/S cell cycle arrest and dysregulate the mRNA expression of cell cycle-associated proteins (proliferating cell nuclear antigen, cyclin E, cyclin A1, cyclin A2 and p21) in NSCLC cells. Notably, miR-137 could significantly suppress SRC3 3' untranslated region (UTR) luciferase-reporter activity, an effect that was not detectable when the putative 3'-UTR target-site was mutated, further clarifying the molecular mechanisms underlying the role of miR-137 in NSCLC. In conclusion, the results of the present study suggest that miR-137 suppresses NSCLC cell proliferation by partially targeting SRC3.

MicroRNA-137 chemosensitizes colon cancer cells to the chemotherapeutic drug oxaliplatin (OXA) by targeting YBX1

The mechanisms underlying oxaliplatin (OXA) resistance in colon cancer cells are not fully understood. MicroRNAs (miRNAs) play important roles in tumorigenesis and drug resistance. However, the relationship between miRNA and OXA resistance in colon cancer cells has not been previously explored. In this study, we utilized microRNA microarray analysis and real-time PCR to verify that miR-93, miR-191, miR-137, miR-181 and miR-491-3p were significantly down-regulated and that miR-96, miR-21, miR-22, miR-15b and miR-92 were up-regulated in both HCT-15/OXA and SW480/OXA cell lines. Blocking miR-137 caused a significant inhibition of OXA-induced cytotoxicity, therefore, miR-137 was chosen for further research. An in vitro cell viability assay showed that knockdown of miR-137 in HCT-15 and SW480 cells caused a marked inhibition of OXA-induced cytotoxicity. Moreover, we found that miR-137 was involved in repression of YBX1 expression through targeting its 3'-untranslated region. Furthermore, down-regulation of miR-137 conferred OXA resistance in parental cells, while over-expression of miR-137 sensitized resistant cells to OXA, which was partly rescued by YBX1 siRNA. The results of this study may aid the development of therapeutic strategies to overcome colon cancer cell resistance to OXA.

Oncogene LSD1 is epigenetically suppressed by miR-137 overexpression in human non-small cell lung cancer

PURPOSE

We examined the epigenetic regulation of microRNA-137 (miR-137) on lysine-specific demethylase 1 (KDM1A, or LSD1) induced oncogenic effects in NSCLC.

METHODS

NSCLC cell lines, A549 and H460 cells were transfected with a mammalian LSD1 overexpression plasmid. It's effects on endogenous KDM1A gene and LSD1 protein expressions were examined by qRT-PCR and western blot assays. NSCLC proliferation and migration were also examined by MTT proliferation and wound-scratch assays, respectively. In LSD1-overexpeseed NSCLC cells, lentiviral transfection was conducted to upregulated miR-137 expression. The subsequent effects of miR-137 upregulation on LSD1-mediated cancer regulations were also examined. In addition, key components of histone deacetylases-associated signaling pathways, including EZH2, HDAC1 and HDAC2 were also examined by western blot in LSD1-and miR-137-mediated NSCLC cells.

RESULTS

Mammalian LSD1 overexpression plasmid was efficient in upregulating KDM1A gene and LSD1 protein in A549 and H460 cells. It also exerted oncogenic effects in NSCLC by promoting cancer proliferation and migration. MiR-137 was inversely correlated with LSD1 in NSCLC, as lentivirus-mediated miR-137 upregulation suppressed KDM1A/LSD1 productions and inhibited proliferation or migration in LSD1-overexpressed A549 and H460 cells. Further western blot analysis demonstrated EZH2, HDAC1 and HDAC2 were activated by LSD1, but inhibited by miR-137 in NSCLC.

CONCLUSION

Oncogenic effects of LSD1 were reversely regulated by its upstream epigenetic modulator miR-137 in NSCLC. The interaction between LSD1 and miR-137 may very well involve the regulation on histone deacetylases-associated signaling pathways.

MiR-137: an important player in neural development and neoplastic transformation

MicroRNAs (miRNAs) represent an important class of small regulatory RNAs that control gene expression posttranscriptionally by targeting mRNAs for degradation or translation inhibition. Early studies have revealed a complex role for miRNAs in major biological processes such as development, differentiation, growth and metabolism. MiR-137 in particular, has been of great interest due to its critical role in brain function and putative involvement in the etiology of both neuropsychiatric disorders and cancer. Several lines of evidence suggest that development, differentiation and maturation of the nervous system is strongly linked to the expression of miR-137 and its regulation of a large number of downstream target genes in various pathways. Dysregulation of this molecule has also been implicated in major mental illnesses through its position in a variant allele highly associated with schizophrenia in the largest mega genome-wide association studies. Interestingly, miR-137 has also been shown to act as a tumor suppressor, with numerous studies finding reduced expression in neoplasia including brain tumor. Restoration of miR-137 expression has also been shown to inhibit cell proliferation, migration and metastasis, and induce cell cycle arrest, differentiation and apoptosis. These properties of miR-137 propose its potential for prognosis, diagnosis and as a therapeutic target for treatment of several human neurological and neoplastic disorders. In this review, we provide details on the discovery, targets, function, regulation and disease involvement of miR-137 with a broad look at recent discovery in this area.

Expression of miR-18a and miR-210 in Normal Breast Tissue as Candidate Biomarkers of Breast Cancer Risk

miRNAs are noncoding RNAs with abnormal expression in breast cancer; their expression in high-risk benign breast tissue may relate to breast cancer risk. We examined miRNA profiles in contralateral unaffected breasts (CUB) of patients with breast cancer and validated resulting candidates in two additional sample sets. Expression profiles of 754 mature miRNAs were examined using TaqMan Low Density Arrays in 30 breast cancer samples [15 estrogen receptor (ER)-positive and 15 ER-negative] and paired CUBs and 15 reduction mammoplasty controls. Pairwise comparisons identified miRNAs with significantly differential expression. Seven candidate miRNAs were examined using qRT-PCR in a second CUB sample set (40 cases, 20 ER+, 20 ER-) and 20 reduction mammoplasty controls. Further validation was performed in 80 benign breast biopsy (BBB) samples; 40 from cases who subsequently developed breast cancer and 40 from controls who did not. Logistic regression, using tertiles of miRNA expression, was used to discriminate cases from controls. Seven miRNAs were differentially expressed in tumors and CUBs versus reduction mammoplasty samples. Among them, miR-18a and miR-210 were validated in the second CUB set, showing significantly higher expression in tumor and CUBs than in reduction mammoplasty controls. The expression of miR-18a and miR-210 was also significantly higher in BBB cases than in BBB controls. When both miR-18a and miR-210 were expressed in the upper tertiles in BBB, OR for subsequent cancer was 3.20, P = 0.023. miR-18a and miR-210 are expressed at higher levels in CUBs of patients with breast cancer, and in BBB prior to cancer development, and are therefore candidate breast cancer risk biomarkers. Cancer Prev Res; 10(1); 89-97. ©2016 AACR.