Decreased expression of microRNA-26b in locally advanced and inflammatory breast cancer

Multiplex Analysis of Cerebrospinal Fluid and Serum Exosomes MicroRNAs of Untreated Relapsing Remitting Multiple Sclerosis (RRMS) and Proposing Noninvasive Diagnostic Biomarkers

Exosomal microRNAs (miRNAs) are emerging diagnostic biomarkers for neurodegenerative diseases. In this study, we aimed to detect relapsing-remitting multiple sclerosis (RRMS)-specific miRNAs in cerebrospinal fluid (CSF) and serum exosomes with diagnostic potential. One ml of CSF and serum sample were collected from each of the 30 untreated RRMS patients and healthy controls (HCs). A panel of 18 miRNAs affecting inflammatory responses was applied, and qRT-PCR was conducted to detect differentially expressed exosomal miRNAs in CSF and serum of RRMS patients. We identified that 17 out of 18 miRNAs displayed different patterns in RRMS patients compared to HCs. Let-7 g-5p, miR-18a-5p, miR-145-5p, and miR-374a-5p with dual pro-inflammatory and anti-inflammatory actions and miR-150-5p and miR-342-3p with anti-inflammatory action were significantly upregulated in both CSF and serum-derived exosomes of RRMS patients compared to corresponding HCs. Additionally, anti-inflammatory miR-132-5p and pro-inflammatory miR-320a-5p were significantly downregulated in both CSF and serum-derived exosomes of RRMS patients compared to HCs. Ten of 18 miRNAs were differentially expressed in CSF and serum exosomes of the patients. Furthermore, miR-15a-5p, miR-19b-3p, and miR-432-5p were upregulated, and miR-17-5p was downregulated only in CSF exosomes. Interestingly, U6 housekeeping gene was differentially expressed in CSF and serum exosomes, in both RRMS and HCs. As the first report describing CSF exosomal miRNAs expression profile compared to that of serum exosomes in untreated RRMS patients, we showed that CSF and serum exosomes are not identical in terms of biological compounds and display different patterns in miRNAs and U6 expression.

microRNA-26b inhibits growth and cellular invasion of ovarian cancer cells by targeting estrogen receptor α

The current study set out to elucidate the mechanism of miR-26b in OC cell proliferation and EMT via suppression of ERα. Initial findings illustrated that miR-26b was poorly expressed in OC tissues and cells. On the other hand, over-expression of miR-26b exerted a diminishing effect on SKOV3 cell proliferation, migration, invasion and EMT, whereas silencing of miR-26b conferred an enhancing effect on CAOV3 cell proliferation, migration, invasion and EMT. Subsequently, with help from the TargetScan database, a dual-luciferase reporter gene assay was carried out to verify the targeting relation between miR-26b and ERα, which revealed that miR-26b could negatively modulate ERα. Furthermore, the in vivo experimentation illustrated that over-expression of miR-26b led to down-regulation of ERα and suppression OC tumor growth and EMT. Meanwhile, silencing of ERα inhibited OC cell proliferation, migration, invasion and EMT. In conclusion, our findings indicated that miR-26b inhibited OC cell proliferation and EMT via negative-modulation of ERα. This investigation may offer potential strategy for OC treatment.

Supplementary Information

The online version contains supplementary material available at 10.1007/s13205-022-03222-2.

The crucial role of epigenetic regulation in breast cancer anti-estrogen resistance: Current findings and future perspectives

Breast cancer (BC) cell de-sensitization to Tamoxifen (TAM) or other selective estrogen receptor (ER) modulators (SERM) is a complex process associated with BC heterogeneity and the transformation of ER signalling. The most influential resistance-related mechanisms include modifications in ER expression and gene regulation patterns. During TAM/SERM treatment, epigenetic mechanisms can effectively silence ER expression and facilitate the development of endocrine resistance. ER status is efficiently regulated by specific epigenetic tools including hypermethylation of CpG islands within ER promoters, increased histone deacetylase activity in the ER promoter, and/or translational repression by miRNAs. Over-methylation of the ER α gene (ESR1) promoter by DNA methyltransferases was associated with poor prognosis and indicated the development of resistance. Moreover, BC progression and spreading were marked by transformed chromatin remodelling, post-translational histone modifications, and expression of specific miRNAs and/or long non-coding RNAs. Therefore, targeted inhibition of histone acetyltransferases (e.g. MYST3), deacetylases (e.g. HDAC1), and/or demethylases (e.g. lysine-specific demethylase LSD1) was shown to recover and increase BC sensitivity to anti-estrogens. Indicated as a powerful molecular instrument, the administration of epigenetic drugs can regain ER expression along with the activation of tumour suppressor genes, which can in turn prevent selection of resistant cells and cancer stem cell survival. This review examines recent advances in the epigenetic regulation of endocrine drug resistance and evaluates novel anti-resistance strategies. Underlying molecular mechanisms of epigenetic regulation will be discussed, emphasising the utilization of epigenetic enzymes and their inhibitors to re-program irresponsive BCs.

MiR-26b-5p inhibits cell proliferation and EMT by targeting MYCBP in triple-negative breast cancer

Background

The study was designed to elucidate the association and functional roles of miR-26b-5p and c-MYC binding protein (MYCBP) in triple-negative breast cancer (TNBC).

Method

Luciferase reporter assay was used to confirm the relationship between miR-26b-5p and MYCBP in TNBC cells. The expression levels of miR-26b-5p and MYCBP in tissue specimens and cell lines were determined using reverse transcription-quantitative PCR. Cell proliferation, migration and invasion were assessed using CCK-8 assay, colony formation and transwell assay.

Results

We first observed that miR-26b-5p directly targets the 3′-UTR of MYCBP to inhibit MYCBP expression in MDA-MB-468 and BT-549 cells. The expression of miR-26b-5p was inversely correlated with MYCBP expression in TNBC tissues. We further demonstrated that MYCBP knockdown suppressed the proliferation, migration and invasion of TNBC cells. Furthermore, MYCBP overexpression counteracted the suppressive effect of miR-26b-5p on TNBC cell behaviors. Western blot analysis demonstrated that the E-cadherin protein level was increased, while protein levels of N-cadherin and vimentin were decreased in cells transfected with miR-26b-5p, which were all reversed by ectopic expression of MYCBP.

Conclusions

In summary, our findings revealed the tumor suppressive role of miR-26b-5p in regulating TNBC cell proliferation and mobility, possibly by targeting MYCBP.

The molecular mechanisms and therapeutic potential of EZH2 in breast cancer

Due to its high occurrence and mortality rate, breast cancer has been studied from various aspects as one of the cancer field's hot topics in the last decade. Epigenetic alterations are spoused to be highly effective in breast cancer development. Enhancer of zeste homolog 2 (EZH2) is an enzymatic epi-protein that takes part in most vital cell functions by its different action modes. EZH2 is suggested to be dysregulated in specific breast cancer types, particularly in advanced stages. Mounting evidence revealed that EZH2 overexpression or dysfunction affects the pathophysiology of breast cancer. In this review, we discuss biological aspects of the EZH2 molecule with a focus on its newly identified action mechanisms. We also highlight how EZH2 plays an essential role in breast cancer initiation, progression, metastasis, and invasion, which emerged as a worthy target for treating breast cancer in different approaches.

The effects of miR-26b-5p on fibroblast-like synovial cells in rheumatoid arthritis (RA-FLS) via targeting EZH2

OBJECTIVE

To study the possible effects of miR-26b-5p on fibroblast-like synovial cells in rheumatoid arthritis (RA-FLS) through targeting enhancer of zeste homolog 2 (EZH2).

METHODS

Quantitative real-time polymerase chain reaction (qRT-PCR) was used to detect miR-26b-5p and EZH2 expressions in synovial tissues of RA patients and healthy controls. Dual luciferase reporter assay was adopted to verify the targeting relationship between miR-26b-5p and EZH2. RA-FLS was divided into Blank, mimics NC, mimics, NC siRNA, EZH2 siRNA and inhibitors + EZH2 siRNA groups, followed by the assessment of proliferation, apoptosis, migration and invasion. The expression of genes and proteins in RA-FLS was tested by qRT-PCR and western blotting, respectively.

RESULTS

MiR-26b-5p expression was lower, while EZH2 expression was higher in synovial tissue of RA patients than healthy controls; and miR-26b-5p was negatively correlated with the EZH2 in synovial tissue of RA patients, which were both related with disease activities. MiR-26b-5p can target EZH2 in RA-FLS. In vitro, miR-26b-5p mimics down-regulated EZH2 expression in RA-FLS. Compared with EZH2 siRNA group, the miR-26b-5p expression in inhibitors + EZH2 siRNA group was reduced, but EZH2 expression was increased. EZH2 siRNA inhibited the proliferation, invasion and migration of RA-FLS, promoted cell apoptosis, and inhibited the expression of TNF-α, IL-1β, IL-6, IL-17, MMP-2, MMP-9, which were reversed by miR-26b-5p inhibitor.

CONCLUSION

MiR-26b-5p may affect the biological characteristics of RA-FLS via targeting EZH2, including proliferation, apoptosis, invasion and migration, as well as the secretion of cytokines, thus playing a potential therapeutic role in RA.

Combinatorial targeting of microRNA-26b and microRNA-101 exerts a synergistic inhibition on cyclooxygenase-2 in brain metastatic triple-negative breast cancer cells

PURPOSE

Extravasation of triple-negative (TN) metastatic breast cancer (BC) cells through the brain endothelium (BE) is a critical step in brain metastasis (BM). During extravasation, metastatic cells induce alteration in the inter-endothelial junctions and transmigrate through the endothelial barrier. Transmigration of metastatic cells is mediated by the upregulation of cyclooxygenase-2 (COX-2) that induces matrix metalloproteinase-1 (MMP-1) capable of degrading inter-endothelial junctional proteins. Despite their important role in BM, the molecular mechanisms upregulating COX-2 and MMP-1 in TNBC cells remain poorly understood. In this study, we unraveled a synergistic effect of a pair of micro-RNAs (miR-26b-5p and miR-101-3p) on COX-2 expression and the brain transmigration ability of BC cells.

METHODS

Using a gain-and-loss of function approach, we modulated levels of miR-26b-5p and miR-101-3p in two TNBC cell lines (the parental MDA-MB-231 and its brain metastatic variant MDA-MB-231-BrM2), and examined the resultant effect on COX-2/MMP-1 expression and the transmigration of cancer cells through the BE.

RESULTS

We observed that the dual inhibition of miR-26b-5p and miR-101-3p in BC cells results in higher increase of COX-2/MMP-1 expression and a higher trans-endothelial migration compared to either micro-RNA alone. The dual restoration of both micro-RNAs exerted a synergistic inhibition on COX-2/MMP-1 by targeting COX-2 and potentiated the suppression of trans-endothelial migration compared to single micro-RNA.

CONCLUSION

These findings provide new insights on a synergism between miR-26-5p and miR-101-3p in regulating COX-2 in metastatic TNBC cells and shed light on miR-26-5p and miR-101-3p as prognostic and therapeutic targets that can be exploited to predict or prevent BM.

LncRNA SNHG5 upregulation induced by YY1 contributes to angiogenesis via miR-26b/CTGF/VEGFA axis in acute myelogenous leukemia

Acute myelogenous leukemia (AML) is the most common acute leukemia in adults. Despite great progress has been made in this field, the pathogenesis of AML is still not fully understood. We report here the biological role of lncRNA small nucleolar RNA host gene 5 (SNHG5) in the pathogenesis of AML and the underlying mechanisms. The results showed that lncRNA SNHG5 was highly expressed in AML cancer cell lines. In vitro studies displayed that inhibition of SNHG5 with shRNA resulted in suppression of survival, cell cycle progression, migration/invasion of AML and capacity of adhesion and angiogenesis in human umbilical vein endothelial cells. Mechanistic studies revealed a SNHG5/miR-26b/connective tissue growth factor (CTGF)/vascular endothelial growth factor A (VEGFA) axis in the regulation of AML angiogenesis. Finally, Yin Yang 1 (YY1) was found to transactivate and interact with SNHG5 promoter, leading to the upregulation of SNHG5 in AML. Collectively, upregulation of lncRNA SNHG5 mediated by YY1, activates CTGF/VEGFA via targeting miR-26b to regulate angiogenesis of AML. Our work provides new insights into the molecular mechanisms of AML.

miRNAs: Critical mediators of breast cancer metastatic programming

MicroRNA mediated aberrant gene regulation has been implicated in several diseases including cancer. Recent research has highlighted the role of epigenetic modulation of the complex process of breast cancer metastasis by miRNAs. miRNAs play a crucial role in the process of metastatic evolution by facilitating alterations in the phenotype of tumor cells and the tumor microenvironment that promote this process. They act as critical determinants of the multi-step progression starting from carcinogenesis all the way to organotropism. In this review, we focus on the current understanding of the compelling role of miRNAs in breast cancer metastasis.

MicroRNAs Involved in Inflammatory Breast Cancer: Oncogene and Tumor Suppressors with Possible Targets

Inflammatory breast cancer (IBC) as a rare and highly aggressive type of breast cancer displays phenotypic characteristics. To date, the IBC-associated molecular mechanisms are entirely unknown. In addition, there is an urgent need to identify the new biomarkers involved in the diagnosis and therapeutic purposes of IBC. MicroRNAs, a category of short noncoding RNAs, are capable of controlling the post-transcriptional expression of genes and thus can act as diagnostic predictive tools. In this review, we addressed the status of oncogenic and tumor suppressor miRNA-mediated IBC in current studies. Furthermore, based on their targets, their involvement in cancer progression, angiogenesis, metastasis, and apoptosis were determined.

Checkpoint Inhibitors and Hepatotoxicity

Uncontrolled immune response to a pathogen or any protein can lead to tissue damage and autoimmune diseases, that represent aberrant immune responses of the individual to its own cells and/or proteins. The immune checkpoint system is the regulatory mechanism that controls immune responses. Tumor cells escape the immune surveillance mechanism, avoiding immune detection and elimination by activating these checkpoints and suppressing the anti-tumor response, thus allowing formation of tumors. Antigenic modulation facilitates masking and contributes to the escape of tumor cells. In addition, there are growing cell promoters, like transforming growth factor β (TGF-β), contributing to escape mechanisms. Targeting the immunological escape of malignant cells is the basis of immune oncology. Checkpoint inhibitors, cytokines and their antibodies may enhance the immune system’s response to tumors. Currently, immunomodulatory agents have been designed, evaluated in clinical trials and have been approved by both European and United States Drug Agencies. The present review is a reflection of the increasingly important role of the checkpoint inhibitors. Our aim is to review the side effects with the emphasis on hepatic adverse reactions of these novel biological drug interventions.

miR-26 family and its target genes in tumorigenesis and development

The microRNA-26 family, including miR-26a, miR-26b, miR-1297 and miR-4465, is a group of broadly conserved small RNAs with identical sequences at the seed region. The expression of miR-26 could be induced by hypoxia via a HIF-dependent mechanism, and up-regulated during multiple cell differentiation. Accumulating studies have demonstrated that miR-26 family members could be detected in many different kinds of tumors, and their validated target genes are involved in cell metabolism, proliferation, differentiation, apoptosis, invasion and metastasis. The expression of miR-26 might be a potentially valuable biomarker and a new target for cancer therapy. In this review, miR-26 family and its target genes in tumorigenesis and development will be summarized as follows.

Biomarkers for Inflammatory Breast Cancer: Diagnostic and Therapeutic Utility

Inflammatory breast cancer (IBC) is a rare and highly aggressive subtype of advanced breast cancer. The aggressive behavior, resistance to chemotherapy, angiogenesis, and high metastatic potential are key intrinsic characteristics of IBC caused by many specific factors. Pathogenesis and behavior of IBC are closely related to tumor surrounding inflammatory and immune cells, blood vessels, and extracellular matrix, which are all components of the tumor microenvironment (TME). The tumor microenvironment has a crucial role in the local immune r09esponse. The communication between intrinsic and extrinsic components of IBC and the abundance of cytokines and chemokines in the TME strongly contribute to the aggressiveness and high angiogenic potential of this tumor. Critical modes of interaction are cytokine-mediated communication and direct intercellular contact between cancer cells and tumor microenvironment with a variety of pathway crosstalk. This review aimed to summarize current knowledge of predictive and prognostic biomarkers in IBC.

Epigenetics in Inflammatory Breast Cancer: Biological Features and Therapeutic Perspectives

Evidence has emerged implicating epigenetic alterations in inflammatory breast cancer (IBC) origin and progression. IBC is a rare and rapidly progressing disease, considered the most aggressive type of breast cancer (BC). At clinical presentation, IBC is characterized by diffuse erythema, skin ridging, dermal lymphatic invasion, and peau d'orange aspect. The widespread distribution of the tumor as emboli throughout the breast and intra- and intertumor heterogeneity is associated with its poor prognosis. In this review, we highlighted studies documenting the essential roles of epigenetic mechanisms in remodeling chromatin and modulating gene expression during mammary gland differentiation and the development of IBC. Compiling evidence has emerged implicating epigenetic changes as a common denominator linking the main risk factors (socioeconomic status, environmental exposure to endocrine disruptors, racial disparities, and obesity) with IBC development. DNA methylation changes and their impact on the diagnosis, prognosis, and treatment of IBC are also described. Recent studies are focusing on the use of histone deacetylase inhibitors as promising epigenetic drugs for treating IBC. All efforts must be undertaken to unravel the epigenetic marks that drive this disease and how this knowledge could impact strategies to reduce the risk of IBC development and progression.

MiR-26a/miR-26b represses tongue squamous cell carcinoma progression by targeting PAK1

Background

Tongue squamous cell carcinoma (TSCC) is the most common oral malignancy. Previous studies found that microRNA (miR)-26a and miR-26b were downregulated in TSCC tissues. The current study was designed to explore the effects of miR-26a/miR-26b on TSCC progression and the potential mechanism.

Methods

Expression of miR-26a, miR-26b and p21 Activated Kinase 1 (PAK1) in TSCC tissues and cell lines was detected by reverse transcription- quantitative polymerase chain reaction (RT-qPCR). Flow cytometry analysis was performed to examine cell cycle and apoptosis. Transwell assay was conducted to evaluate the migrated and invasive abilities of SCC4 and Cal27 cells. In addition, western blot assay was employed to analyze the protein level. Glucose assay kit and lactate assay kit were utilized to analyze glycolysis. Dual-luciferase reporter and RNA immunoprecipitation (RIP) assays were applied to explore the relationship between miR-26a/miR-26b and PAK1. Xenograft tumor model was constructed to explore the role of miR-26a/miR-26b in vivo.

Results

Both miR-26a and miR-26b were underexpressed, while PAK1 was highly enriched in TSCC. Overexpression of miR-26a and miR-26b inhibited TSCC cell cycle, migration invasion and glycolysis, while promoted cell apoptosis. Both miR-26a and miR-26b directly targeted and negatively regulated PAK1 expression. Introduction of PAK1 partially reversed miR-26a/miR-26b upregulation-mediated cellular behaviors in TSCC cells. Gain of miR-26a/miR-26b blocked TSCC tumor growth in vivo.

Conclusion

MiR-26a/miR-26b repressed TSCC progression via targeting PAK1 in vitro and in vivo, which enriched our understanding about TSCC development and provided new insights into the its treatment.

MicroRNA Regulation of Epigenetic Modifiers in Breast Cancer

Epigenetics refers to the heritable changes in gene expression without a change in the DNA sequence itself. Two of these major changes include aberrant DNA methylation as well as changes to histone modification patterns. Alterations to the epigenome can drive expression of oncogenes and suppression of tumor suppressors, resulting in tumorigenesis and cancer progression. In addition to modifications of the epigenome, microRNA (miRNA) dysregulation is also a hallmark for cancer initiation and metastasis. Advances in our understanding of cancer biology demonstrate that alterations in the epigenome are not only a major cause of miRNA dysregulation in cancer, but that miRNAs themselves also indirectly drive these DNA and histone modifications. More explicitly, recent work has shown that miRNAs can regulate chromatin structure and gene expression by directly targeting key enzymes involved in these processes. This review aims to summarize these research findings specifically in the context of breast cancer. This review also discusses miRNAs as epigenetic biomarkers and as therapeutics, and presents a comprehensive summary of currently validated epigenetic targets in breast cancer.

Gene co-expression network approach for predicting prognostic microRNA biomarkers in different subtypes of breast cancer

New diagnostic miRNA biomarkers for different types of cancer have been studied extensively, particularly for breast cancer (BC), which is a leading cause of death among women and has many different subtypes. In the present study, a systems biology approach was used to find remarkable and novel miRNA biomarkers for five molecular subtypes of BC: luminal A, luminal B, ERBB2, basal-like and normal-like. The mRNA expression data from the five BC subtypes was used to reconstruct co-expression networks. The important mRNA-miRNA interactions were considered when reconstructing the bipartite networks from which the five bipartite sub-networks were reconstructed for further analysis. The novel biomarkers detected for each subtype are as follows: miRNAs 26b-5p and 124-3p for basal-like, 26b-5p, 124-3p and 5011-5p for ERBB2, 26b-5p and 5011-5p for LumA, 124-3p, 26b-5p and 7-5p for LumB and 26b-5p, 124-3p and 193b-3p for normal-like. The roles of the identified miRNAs in the occurrence or development of each subtype of BC remain unclear and should be investigated in future studies. In addition, the target genes of these miRNAs may be critical to the mechanisms underlying each subtype and should be analyzed as therapeutic targets in future studies.

Understanding the tumour micro-environment communication network from an NOS2/COX2 perspective

Recent findings suggest that co-expression of NOS2 and COX2 is a strong prognostic indicator in triple-negative breast cancer patients. These two key inflammation-associated enzymes are responsible for the biosynthesis of NO and PGE2 , respectively, and can exert their effect in both an autocrine and paracrine manner. Impairment of their physiological regulation leads to critical changes in both intra-tumoural and intercellular communication with the immune system and their adaptation to the hypoxic tumour micro-environment. Recent studies have also established a key role of NOS2-COX2 in causing metabolic shift. This review provides an extensive overview of the role of NO and PGE2 in shaping communication between the tumour micro-environment composed of tumour and immune cells that in turn favours tumour progression and metastasis. LINKED ARTICLES: This article is part of a themed section on Nitric Oxide 20 Years from the 1998 Nobel Prize. To view the other articles in this section visit http://onlinelibrary.wiley.com/doi/10.1111/bph.v176.2/issuetoc.