MicroRNA-101-mediated Akt activation and estrogen-independent growth

The Impact of miRNAs on the Efficacy of Tamoxifen in Breast Cancer Treatment: A Systematic Review

Seventy percent of breast cancer patients have an active estrogen receptor. Tamoxifen interferes with estrogen's ability to bind to cancer cells. The most challenging aspect of tamoxifen, however, is that breast cancer cells become resistant to its effects. Some studies have shown that alterations in miRNA expression contribute significantly to drug resistance in breast cancer. Therefore, the present systematic review aims to investigate miRNAs that significantly influence the response to tamoxifen treatment. The present study follows the PRISMA instructions. The Web of Science, PubMed, and Scopus databases were searched to retrieve English articles. The searches were conducted up to September 11, 2022. The search strategy included the terms "Tamoxifen", "Breast Neoplasm", and "MicroRNA". The inclusion criteria of this study are English, original, and experimental studies investigating miRNAs that are effective in the treatment efficacy of tamoxifen. A total of 565 articles were retrieved. After screening, 75 studies met our inclusion criteria. This systematic review study examined 105 miRNAs, of which 44 have a positive effect, and 47 miRNAs inhibit tamoxifen function. Fourteen miRNAs have a controversial effect, ie, some studies show positive and negative effects. The study of miRNAs affecting tamoxifen function in breast cancer patients may facilitate the identification of individuals at higher risk of disease recurrence. Conversely, it can potentially utilize appropriate interventions to defeat drug resistance effectively.

Extracellular vesicle-mediated drug delivery in breast cancer theranostics

Breast cancer (BC) continues to be a significant global challenge due to drug resistance and severe side effects. The increasing prevalence is alarming, requiring new therapeutic approaches to address these challenges. At this point, Extracellular vesicles (EVs), specifically small endosome-released nanometer-sized EVs (SEVs) or exosomes, have been explored by literature as potential theranostics. Therefore, this review aims to highlight the therapeutic potential of exosomes in BC, focusing on their advantages in drug delivery and their ability to mitigate metastasis. Following the review, we identified exosomes' potential in combination therapies, serving as miRNA carriers and contributing to improved anti-tumor effects. This is evident in clinical trials investigating exosomes in BC, which have shown their ability to boost chemotherapy efficacy by delivering drugs like paclitaxel (PTX) and doxorubicin (DOX). However, the translation of EVs into BC therapy is hindered by various challenges. These challenges include the heterogeneity of EVs, the selection of the appropriate parent cell, the loading procedures, and determining the optimal administration routes. Despite the promising therapeutic potential of EVs, these obstacles must be addressed to realize their benefits in BC treatment.

Identification of Exo-miRNAs: A Summary of the Efforts in Translational Studies Involving Triple-Negative Breast Cancer

Triple-negative breast cancer (TNBC) accounts for about 10-15% of all breast cancers (BC) in the US and its diagnosis is associated with poor survival outcomes. A better understanding of the disease etiology is crucial to identify target treatment options to improve patient outcomes. The role of exo-miRNAs in TNBC has been studied for more than two decades. Although some studies have identified exo-miR candidates in TNBC using clinical samples, consensus regarding exo-miR candidates has not been achieved. The purpose of this review is to gather information regarding exo-miR candidates reported in TNBC translational studies along with the techniques used to isolate and validate the potential targets. The techniques suggested in this review are based on the use of commercially available materials for research and clinical laboratories. We expect that the information included in this review can add additional value to the recent efforts in the development of a liquid biopsy to identify TNBC cases and further improve their survival outcomes.

An Update on Tamoxifen and the Chemo-Preventive Potential of Vitamin E in Breast Cancer Management

Breast cancer (BC) is the most common female cancer in terms of incidence and mortality worldwide. Tamoxifen (Nolvadex) is a widely prescribed, oral anti-estrogen drug for the hormonal treatment of estrogen-receptor-positive BC, which represents 70% of all BC subtypes. This review assesses the current knowledge on the molecular pharmacology of tamoxifen in terms of its anticancer and chemo-preventive actions. Due to the importance of vitamin E compounds, which are widely taken as a supplementary dietary component, the review focuses only on the potential importance of vitamin E in BC chemo-prevention. The chemo-preventive and onco-protective effects of tamoxifen combined with the potential effects of vitamin E can alter the anticancer actions of tamoxifen. Therefore, methods involving an individually designed, nutritional intervention for patients with BC warrant further consideration. These data are of great importance for tamoxifen chemo-prevention strategies in future epidemiological studies.

Exosomal miRNAs as novel avenues for breast cancer treatment

Breast cancer is the most commonly diagnosed cancer and a leading cause of death in women worldwide. It is a heterogeneous disease, as shown by the gene expression profiles of breast cancer samples. It begins in milk-producing ducts, with a high degree of diversity between and within tumors, as well as among cancer-bearing individuals. The enhanced prevalence of breast cancer is influenced by various hormonal, lifestyle, and environmental factors, and very early onset of the disease correlates strongly with the risk of local and distant recurrence. Many subtypes are difficult to treat with conventional therapeutic modalities, and therefore, optimal management and early diagnosis are the first steps to minimizing the mortality linked with breast cancer. The use of newer methods of nanotechnology extends beyond the concept of synthesizing drug delivery mechanisms into the creation of new therapeutics, such as delivering chemotherapeutics with nanomaterial properties. Exosomes, a class of nanovesicles, are emerging as novel tools for deciphering the patient-specific proteins and biomarkers across different disease models, including breast cancer. In this review, we address the role of exosomal miRNA in breast cancer diagnosis and treatment.

N6-methyladenosine modified LINC00901 promotes pancreatic cancer progression through IGF2BP2/MYC axis

Accumulating evidence indicates that RNA methylation at N6-methyladenosine (m6A) plays an important regulatory role in gene expression and aberrant mRNA m6A modification is often associated with a variety of cancers. However, little is known whether and how m6A-modification impacts long non-coding RNA (lncRNA) and lncRNA-mediated tumorigenesis, particularly in pancreatic ductal adenocarcinoma (PDAC). In the present study, we report that a previously uncharacterized lncRNA, LINC00901, promotes pancreatic cancer cell growth and invasion and moreover, LINC00901 is subject to m6A modification which regulates its expression. In this regard, YTHDF1 serves as a reader for the m6A modified LINC00901 and downregulates the LINC00901 level. Notably, two conserved m6A sites in LINC00901 are critical to the recognition of LINC00901 by YTHDF1. Finally, RNA sequencing (RNA-seq) and gene function analysis revealed that LINC00901 positively regulates MYC through upregulation of IGF2BP2, a known RNA binding protein that can enhance MYC mRNA stability. Together, our results suggest that there is a LINC00901-IGF2BP2-MYC axis through which LINC00901 promotes PDAC progression in an m6A dependent manner.

MiR-101: An Important Regulator of Gene Expression and Tumor Ecosystem

MiRNAs are small single-stranded non-coding RNAs. MiRNA contributes to the transcriptional and post-transcriptional regulation of mRNA in different cell types, including mRNA transcription inhibition and mRNA decay and phenotypes via the effect of several essential oncogenic processes and tumor microenvironment. MiR-101 is a highly conserved miRNA that was found to alter the expression in various human cancers. MiR-101 has been reported to have tumor oncogenic and suppressive effects to regulate tumorigenesis and tumor progression. In this review, we summarize the new findings about the roles of miR-101 in cancers and the underlying mechanisms of targeting genes degradation and microenvironment regulation, which will improve biological understanding and design of novel therapeutics.

LncRNA SNHG6 sponges miR-101 and induces tamoxifen resistance in breast cancer cells through induction of EMT

Acquired resistance is a major clinical challenge for tamoxifen-based therapy. In this study, we focused on lncRNA SNHG6 which plays a role in chemoresistance of cancer cells, but has never been investigated in the context of tamoxifen resistance. We found elevated levels of SNHG6 in tamoxifen-resistant estrogen receptor (ER)-positive MCF-7 cells (MCF7TR), relative to naïve MCF-7 cells, as well as in tamoxifen-resistant T47D cells (T47DTR), relative to naïve T47D cells, which correlated with induced vimentin, ZEB1/2 and decreased e-cadherin, thus implicating a role of EMT in SNHG6-mediated tamoxifen resistance. Downregulation of SNHG6, using specific siRNA, sensitized MCF7TR as well as T47DTR cells to tamoxifen along with markedly reduced proliferation, invasion and anchorage-independent clonogenicity. Further, SNHG6 was found to sponge and inhibit miR-101 as the endogenous expression levels of SNHG6 and miR-101 inversely correlated in paired parental and tamoxifen-resistant cells and, moreover, silencing of SNHG6 in tamoxifen-resistant cells resulted in de-repression of miR-101, along with reversal of EMT. SNHG6 expression also directly correlated with increased stem cells markers Sox2, Oct4 and EZH2. miR-101 levels, manipulated by transfections with pre/anti-miR-101 oligos, directly affected tamoxifen sensitivity of ER-positive cells with pre-miR-101 sensitizing MCF7TR and T47DTR cells to tamoxifen whereas anti-miR-101 inducing resistance of parental MCF-7 and T47D cells to tamoxifen. Further, miR-101 was found to attenuate SNHG6-mediated effects on tamoxifen resistance, EMT as well as stem cell markers, thereby making a case for SNHG6-miR-101 axis in tamoxifen resistance of ER-positive breast cancer cells. Thus, lncRNA SNHG6 is a novel modulator of tamoxifen resistance through its sponging of miR-101 and the resulting effects on EMT.

The role and application of small extracellular vesicles in breast cancer

Breast cancer (BC) is the most common malignancy and the leading cause of cancer-related deaths in women worldwide. Currently, patients’ survival remains a challenge in BC due to the lack of effective targeted therapies and the difficult condition of patients with higher aggressiveness, metastasis and drug resistance. Small extracellular vesicles (sEVs), which are nanoscale vesicles with lipid bilayer envelopes released by various cell types in physiological and pathological conditions, play an important role in biological information transfer between cells. There is growing evidence that BC cell-derived sEVs may contribute to the establishment of a favorable microenvironment that supports cancer cells proliferation, invasion and metastasis. Moreover, sEVs provide a versatile platform not only for the diagnosis but also as a delivery vehicle for drugs. This review provides an overview of current new developments regarding the involvement of sEVs in BC pathogenesis, including tumor proliferation, invasion, metastasis, immune evasion, and drug resistance. In addition, sEVs act as messenger carriers carrying a variety of biomolecules such as proteins, nucleic acids, lipids and metabolites, making them as potential liquid biopsy biomarkers for BC diagnosis and prognosis. We also described the clinical applications of BC derived sEVs associated MiRs in the diagnosis and treatment of BC along with ongoing clinical trials which will assist future scientific endeavors in a more organized direction.

The magic of MAGI-1: A scaffolding protein with multi signalosomes and functional plasticity

MAGI-1 is a critical cellular scaffolding protein with over 110 different cellular and microbial protein interactors. Since the discovery of MAGI-1 in 1997, MAGI-1 has been implicated in diverse cellular functions such as polarity, cell-cell communication, neurological processes, kidney function, and a host of diseases including cancer and microbial infection. Additionally, MAGI-1 has undergone nomenclature changes in response to the discovery of an additional PDZ domain, leading to lack of continuity in the literature. We address the nomenclature of MAGI-1 as well as summarize many of the critical functions of the known interactions. Given the importance of many of the interactors, such as human papillomavirus E6, the Coxsackievirus and adenovirus receptor (CAR), and PTEN, the enhancement or disruption of MAGI-based interactions has the potential to affect cellular functions that can potentially be harnessed as a therapeutic strategy for a variety of diseases.

The Role of Microbiota in the Immunopathogenesis of Endometrial Cancer

The female reproductive tract hosts a specific microbiome, which plays a crucial role in sustaining equilibrium and good health. In the majority of reproductive women, the microbiota (all bacteria, viruses, fungi, and other single-celled organisms within the human body) of the vaginal and cervical microenvironment are dominated by Lactobacillus species, which benefit the host through symbiotic relationships, in comparison to the uterus, fallopian tubes, and ovaries, which may contain a low-biomass microbiome with a diverse mixture of microorganisms. Although disruption to the balance of the microbiota develops, the altered immune and metabolic signaling may cause an impact on diseases such as cancer. These pathophysiological modifications in the gut–uterus axis may spark gynecological cancers. New information displays that gynecological and gastrointestinal tract dysbiosis (disruption of the microbiota homeostasis) can play an active role in the advancement and metastasis of gynecological neoplasms, such as cervical, endometrial, and ovarian cancers. Understanding the relationship between microbiota and endometrial cancer is critical for prognosis, diagnosis, prevention, and the development of innovative treatments. Identifying a specific microbiome may become an effective method for characterization of the specific microbiota involved in endometrial carcinogenesis. The aim of this study was to summarize the current state of knowledge that describes the correlation of microbiota with endometrial cancer with regard to the formation of immunological pathologies.

Matrix Metalloproteinase-1 (MMP1) Upregulation through Promoter Hypomethylation Enhances Tamoxifen Resistance in Breast Cancer

Simple Summary

Cancer recurrence caused by tamoxifen resistance hampers chemotherapy in breast cancer patients. The reasons behind the resistance were investigated by screening epigenetically regulated genes through analysis of methylation data from tamoxifen-resistant MCF-7 cells. MMP1 locus was found to be hypomethylated at a promoter CpG site and its expression was upregulated in the cell line, which was verified by the drug-resistant tumor tissues from breast cancer patients (n = 28). Downregulating MMP1 using a short hairpin RNA inhibited the growth of resistant cells and increased sensitivity to tamoxifen in vitro as well as in a xenografted mouse model in vivo. This study suggests that MMP1 is potentially a target gene to control tamoxifen resistance in breast cancer.

Abstract

Background: Tamoxifen (tam) is widely used to treat estrogen-positive breast cancer. However, cancer recurrence after chemotherapy remains a major obstacle to achieve good patient prognoses. In this study, we aimed to identify genes responsible for epigenetic regulation of tam resistance in breast cancer. Methods: Methylation microarray data were analyzed to screen highly hypomethylated genes in tam resistant (tamR) breast cancer cells. Quantitative RT-PCR, Western blot analysis, and immunohistochemical staining were used to quantify expression levels of genes in cultured cells and cancer tissues. Effects of matrix metalloproteinase-1 (MMP1) expression on cancer cell growth and drug resistance were examined through colony formation assays and flow cytometry. Xenografted mice were generated to investigate the effects of MMP1 on drug resistance in vivo. Results: MMP1 was found to be hypomethylated and overexpressed in tamR MCF-7 (MCF-7/tamR) cells and in tamR breast cancer tissues. Methylation was found to be inversely associated with MMP1 expression level in breast cancer tissues, and patients with lower MMP1 expression exhibited a better prognosis for survival. Downregulating MMP1 using shRNA induced tam sensitivity in MCF-7/tamR cells along with increased apoptosis. The xenografted MCF-7/tamR cells that stably expressed short hairpin RNA (shRNA) against MMP1 exhibited retarded tumor growth compared to that in cells expressing the control shRNA, which was further suppressed by tam. Conclusions: MMP1 can be upregulated through promoter hypomethylation in tamR breast cancer, functioning as a resistance driver gene. MMP1 can be a potential target to suppress tamR to achieve better prognoses of breast cancer patients.

Comparison of MicroRNA Profiles in Extracellular Vesicles from Small and Large Goat Follicular Fluid

Simple Summary

Ovarian follicular development is associated with ovulation and is further related to litter size in goats. Extracellular vesicles (EVs) derived from miRNAs within follicular fluid undergo dynamic changes, and, together with follicle growth, may be considered as potential regulators of follicular development. However, the function and changes in EVs remain ambiguous. Here, we identified miRNA changes in EVs from small to large goat follicular fluid. Using bioinformatics tools, we demonstrated the existence of differentially expressed miRNAs in EVs from follicles of different sizes that are responsible for an altered biological effect. This study contributes to a better understanding of follicular development in goats.

Abstract

Extracellular vesicles (EVs), which exist in the follicular fluid of ruminant ovaries, are considered as cargo carriers for the transfer of biomolecules to recipient cells. However, the functions and changes in EVs in antral follicles remain ambiguous. In the present study, we isolated and characterized EVs from goat follicular fluid by means of differential ultracentrifugation and Western blotting of marker proteins. Bioinformatics tools were used to detect miRNA expression levels in EVs. Different miRNA expression patterns of EVs exist in small to large follicles. Thirteen differentially expressed miRNAs (seven upregulated and six downregulated) were identified and used for analysis. A total of 1948 predicted target genes of 13 miRNAs were mapped to signaling pathways, and three significantly enriched pathways (FoxO, MAPK, and PI3K-AKT signaling pathways) were involved in follicular development, as revealed by KEGG enrichment analysis. Our findings suggest that EVs in follicular fluid play biofunctional roles during follicular development in goats.

Towards Unravelling the Role of ERα-Targeting miRNAs in the Exosome-Mediated Transferring of the Hormone Resistance

Hormone therapy is one of the most effective breast cancer treatments, however, its application is limited by the progression of hormonal resistance, both primary or acquired. The development of hormonal resistance is caused either by an irreversible block of hormonal signalling (suppression of the activity or synthesis of hormone receptors), or by activation of oestrogen-independent signalling pathways. Recently the effect of exosome-mediated intercellular transfer of hormonal resistance was revealed, however, the molecular mechanism of this effect is still unknown. Here, the role of exosomal miRNAs (microRNAs) in the transferring of hormonal resistance in breast cancer cells has been studied. The methods used in the work include extraction, purification and RNAseq of miRNAs, transfection of miRNA mimetics, immunoblotting, reporter analysis and the MTT test. Using MCF7 breast cancer cells and MCF7/T tamoxifen-resistant sub-line, we have found that some miRNAs, suppressors of oestrogen receptor signalling, are overexpressed in the exosomes of the resistant breast cancer cells. The multiple (but not single) transfection of one of the identified miRNA, miR-181a-2, into oestrogen-dependent MCF7 cells induced the irreversible tamoxifen resistance associated with the continuous block of the oestrogen receptor signalling and the activation of PI3K/Akt pathway. We suppose that the miRNAs-ERα suppressors may act as trigger agents inducing the block of oestrogen receptor signalling and breast cancer cell transition to an aggressive oestrogen-independent state.

MicroRNAs as a clue to overcome breast cancer treatment resistance

Breast cancer is the most frequent cancer in women worldwide. Despite the improvement in diagnosis and treatments, the rates of cancer relapse and resistance to therapies remain higher than desirable. Alterations in microRNAs have been linked to changes in critical processes related to cancer development and progression. Their involvement in resistance or sensitivity to breast cancer treatments has been documented by different in vivo and in vitro experiments. The most significant microRNAs implicated in modulating resistance to breast cancer therapies are summarized in this review. Resistance to therapy has been linked to cellular processes such as cell cycle, apoptosis, epithelial-to-mesenchymal transition, stemness phenotype, or receptor signaling pathways, and the role of microRNAs in their regulation has already been described. The modulation of specific microRNAs may modify treatment response and improve survival rates and cancer patients' quality of life. As a result, a greater understanding of microRNAs, their targets, and the signaling pathways through which they act is needed. This information could be useful to design new therapeutic strategies, to reduce resistance to the available treatments, and to open the door to possible new clinical approaches.

A New Story of the Three Magi: Scaffolding Proteins and lncRNA Suppressors of Cancer

Scaffolding molecules exert a critical role in orchestrating cellular response through the spatiotemporal assembly of effector proteins as signalosomes. By increasing the efficiency and selectivity of intracellular signaling, these molecules can exert (anti/pro)oncogenic activities. As an archetype of scaffolding proteins with tumor suppressor property, the present review focuses on MAGI1, 2, and 3 (membrane-associated guanylate kinase inverted), a subgroup of the MAGUK protein family, that mediate networks involving receptors, junctional complexes, signaling molecules, and the cytoskeleton. MAGI1, 2, and 3 are comprised of 6 PDZ domains, 2 WW domains, and 1 GUK domain. These 9 protein binding modules allow selective interactions with a wide range of effectors, including the PTEN tumor suppressor, the β-catenin and YAP1 proto-oncogenes, and the regulation of the PI3K/AKT, the Wnt, and the Hippo signaling pathways. The frequent downmodulation of MAGIs in various human malignancies makes these scaffolding molecules and their ligands putative therapeutic targets. Interestingly, MAGI1 and MAGI2 genetic loci generate a series of long non-coding RNAs that act as a tumor promoter or suppressor in a tissue-dependent manner, by selectively sponging some miRNAs or by regulating epigenetic processes. Here, we discuss the different paths followed by the three MAGIs to control carcinogenesis.

From Micro to Long: Non-Coding RNAs in Tamoxifen Resistance of Breast Cancer Cells

Breast cancer is the most commonly diagnosed cancer and the leading cause of cancer mortality among women. Two thirds of patients are classified as hormone receptor positive, based on expression of estrogen receptor alpha (ERα), the main driver of breast cancer cell proliferation, and/or progesterone receptor, which is regulated by ERα. Despite presenting the best prognosis, these tumors can recur when patients acquire resistance to treatment by aromatase inhibitors or antiestrogen such as tamoxifen (Tam). The mechanisms that are involved in Tam resistance are complex and involve multiple signaling pathways. Recently, roles for microRNAs and lncRNAs in controlling ER expression and/or tamoxifen action have been described, but the underlying mechanisms are still little explored. In this review, we will discuss the current state of knowledge on the roles of microRNAs and lncRNAs in the main mechanisms of tamoxifen resistance in hormone receptor positive breast cancer. In the future, this knowledge can be used to identify patients at a greater risk of relapse due to the expression patterns of ncRNAs that impact response to Tam, in order to guide their treatment more efficiently and possibly to design therapeutic strategies to bypass mechanisms of resistance.

The regulatory role of pivotal microRNAs in the AKT signaling pathway in breast cancer

Breast cancer is the most prevalent type of cancer among women, and it remains the main challenge despite improved treatments. MicroRNAs (miRNAs) are a small non-coding family of RNAs that play an indispensable role in regulating major physiological processes, including differentiation, proliferation, invasion, migration, cell cycle regulation, stem cell maintenance, apoptosis, and organ development. The dysregulation of these tiny molecules is associated with various human malignancies. More than 50% of these non-coding RNA sequences estimated have been placed on genomic regions or fragile sites linked to cancer. Following the discovery of the first signatures of specific miRNA in breast cancer, numerous researches focused on involving these tiny RNAs in breast cancer physiopathology as a new therapeutic approach or as reliable prognostic biomarkers. In the current review, we focus on recent findings related to the involvement of miRNAs in breast cancer via the AKT signaling pathway and the related clinical implications.

MAGI1, a Scaffold Protein with Tumor Suppressive and Vascular Functions

MAGI1 is a cytoplasmic scaffolding protein initially identified as a component of cell-to-cell contacts stabilizing cadherin-mediated cell–cell adhesion in epithelial and endothelial cells. Clinical-pathological and experimental evidence indicates that MAGI1 expression is decreased in some inflammatory diseases, and also in several cancers, including hepatocellular carcinoma, colorectal, cervical, breast, brain, and gastric cancers and appears to act as a tumor suppressor, modulating the activity of oncogenic pathways such as the PI3K/AKT and the Wnt/β-catenin pathways. Genomic mutations and other mechanisms such as mechanical stress or inflammation have been described to regulate MAGI1 expression. Intriguingly, in breast and colorectal cancers, MAGI1 expression is induced by non-steroidal anti-inflammatory drugs (NSAIDs), suggesting a role in mediating the tumor suppressive activity of NSAIDs. More recently, MAGI1 was found to localize at mature focal adhesion and to regulate integrin-mediated adhesion and signaling in endothelial cells. Here, we review MAGI1′s role as scaffolding protein, recent developments in the understanding of MAGI1 function as tumor suppressor gene, its role in endothelial cells and its implication in cancer and vascular biology. We also discuss outstanding questions about its regulation and potential translational implications in oncology.

Exosomal microRNAs: Pleiotropic Impacts on Breast Cancer Metastasis and Their Clinical Perspectives

As a major threat factor for female health, breast cancer (BC) has garnered a lot of attention for its malignancy and diverse molecules participating in its carcinogenesis process. Among these complex carcinogenesis processes, cell proliferation, epithelial-to-mesenchymal transition (EMT), mesenchymal-to-epithelial transition (MET), and angiogenesis are the major causes for the occurrence of metastasis and chemoresistance which account for cancer malignancy. MicroRNAs packaged and secreted in exosomes are termed "exosomal microRNAs (miRNAs)". Nowadays, more researches have uncovered the roles of exosomal miRNAs played in BC metastasis. In this review, we recapitulated the dual actions of exosomal miRNAs exerted in the aggressiveness of BC by influencing migration, invasion, and distant metastasis. Next, we presented how exosomal miRNAs modify angiogenesis and stemness maintenance. Clinically, several exosomal miRNAs can govern the transformation between drug sensitivity and chemoresistance. Since the balance of the number and type of exosomal miRNAs is disturbed in pathological conditions, they are able to serve as instructive biomarkers for BC diagnosis and prognosis. More efforts are needed to connect the theoretical studies and clinical traits together. This review provides an outline of the pleiotropic impacts of exosomal miRNAs on BC metastasis and their clinical implications, paving the way for future personalized drugs.

Non-coding RNAs related to angiogenesis in gynecological cancer

Gynecological cancer affects the female reproductive system, including ovarian, uterine, endometrial, cervical, vulvar, and vaginal tumors. Non-coding RNAs (ncRNAs), and in particular microRNAs, function as regulatory molecules, which can control gene expression in a post-transcriptional manner. Normal physiological processes like cellular proliferation, differentiation, and apoptosis, and pathological processes such as oncogenesis and metastasis are regulated by microRNAs. Numerous reports have shown a direct role of microRNAs in the modulation of angiogenesis in gynecological cancer, via targeting pro-angiogenic factors and signaling pathways. Understanding the molecular mechanism involved in the regulation of angiogenesis by microRNAs may lead to new treatment options. Recently the regulatory role of some long non-coding RNAs in gynecological cancer has also been explored, but the information on this function is more limited. The aim of this article is to explore the pathways responsible for angiogenesis, and to what extent ncRNAs may be employed as biomarkers or therapeutic targets in gynecological cancer.

MicroRNAs in breast cancer: New maestros defining the melody

MicroRNAs, short non-coding single-stranded RNAs, are important regulators and gatekeepers of the coding genes in the human genome. MicroRNAs are highly conserved among species and expressed in different tissues and cell types. They are involved in almost all the biological processes as apoptosis, proliferation, cell cycle arrest and differentiation. Playing all these roles, it is not surprising that the deregulation of the microRNA profile causes a number of diseases including cancer. Breast cancer, the most commonly diagnosed malignancy in women, accounts for the highest cancer-related deaths worldwide. Different microRNAs were shown to be up or down regulated in breast cancer. MicroRNAs can function as oncogenes or tumor suppressors according to their targets. In this review, the most common microRNAs implicated in breast cancer are fully illustrated with their targets. Besides, the review highlights the effect of exosomal microRNA on breast cancer and the effect of microRNAs on drug and therapies resistance as well as the miRNA-based therapeutic strategies used until today.

microRNA-related single-nucleotide polymorphisms and breast cancer

Breast cancer, as the most common cancer in women which affects patients both mentally and physically, requires great attention in many areas and many levels as this cancer is known to be multifactorial. Single-stranded molecules called microRNAs with near 22 nucleotides are seen to act in central dogma of molecular biology by inhibiting the translation process; it is demonstrated that any alteration in their sequence especially single-nucleotide polymorphisms (SNPs) may lead into increasing the breast cancer risk. miR-SNPs are considered to be the potential biomarkers for early detection of breast cancer. As a result, this review documents the well-known miR-SNPs that are known to be associated with breast cancer. In this regard, two principals were discussed: (a) SNPs in the target genes of microRNAs and the alteration in gene expression due to this phenomenon; (b) changes based on the SNPs in the microRNA coding region and the impact on their interaction with target messenger RNA.

Endoplasmic reticulum stress-induced exosomal miR-27a-3p promotes immune escape in breast cancer via regulating PD-L1 expression in macrophages

Immune escape of breast cancer cells contributes to breast cancer pathogenesis. Tumour microenvironment stresses that disrupt protein homeostasis can produce endoplasmic reticulum (ER) stress. The miRNA‐mediated translational repression of mRNAs has been extensively studied in regulating immune escape and ER stress in human cancers. In this study, we identified a novel microRNA (miR)‐27a‐3p and investigated its mechanistic role in promoting immune evasion. The binding affinity between miR‐27a‐3p and MAGI2 was predicted using bioinformatic analysis and verified by dual‐luciferase reporter assay. Ectopic expression and inhibition of miR‐27a‐3p in breast cancer cells were achieved by transduction with mimics and inhibitors. Besides, artificial modulation of MAGI2 and PTEN was done to explore their function in ER stress and immune escape of cancer cells. Of note, exosomes were derived from cancer cells and co‐cultured with macrophages for mechanistic studies. The experimental data suggested that ER stress biomarkers including GRP78, PERK, ATF6, IRE1α and PD‐L1 were overexpressed in breast cancer tissues relative to paracancerous tissues. Endoplasmic reticulum stress promoted exosome secretion and elevated exosomal miR‐27a‐3p expression. Elevation of miR‐27a‐3p and PD‐L1 levels in macrophages was observed in response to exosomes‐overexpressing miR‐27a‐3p in vivo and in vitro. miR‐27a‐3p could target and negatively regulate MAGI2, while MAGI2 down‐regulated PD‐L1 by up‐regulating PTEN to inactivate PI3K/AKT signalling pathway. Less CD4⁺, CD8⁺ T cells and IL‐2, and T cells apoptosis were observed in response to co‐culture of macrophages and CD3⁺ T cells. Conjointly, exosomal miR‐27a‐3p promotes immune evasion by up‐regulating PD‐L1 via MAGI2/PTEN/PI3K axis in breast cancer.

IGF2BP2 regulates DANCR by serving as an N6-methyladenosine reader

The major function of Insulin-like growth factor 2 mRNA-binding protein 2 (IGF2BP2) is to regulate cell metabolism. However, emerging evidence indicates that IGF2BP2 plays a role in cancer, but the underlying mechanism is largely unknown. Here we showed that upregulation of IGF2BP2 is associated with poor outcomes of pancreatic cancer patients and suppression of IGF2BP2 inhibits cell proliferation. We further showed that IGF2BP2 regulates lncRNA DANCR. Ectopic expression IGF2BP2 enhances, whereas knockdown (KD) or knockout (KO) of IGF2BP2 suppresses DANCR expression. Moreover, in vivo RNA precipitation and reciprocal RNA immunoprecipitation revealed that IGF2BP2 interacts with DANCR. DANCR promotes cell proliferation and stemness-like properties. Experiments with xenograft models revealed that while ectopic expression of DANCR promotes, DANCR KO suppresses tumor growth. Mechanistically, DANCR is modified at N6-methyladenosine (m6A) and mutagenesis assay identified that adenosine at 664 of DANCR is critical to the interaction between IGF2BP2 and DANCR where IGF2BP2 serves a reader for m6A modified DANCR and stabilizes DANCR RNA. Together, these results suggest that DANCR is a novel target for IGF2BP2 through m6A modification, and IGF2BP2 and DANCR work together to promote cancer stemness-like properties and pancreatic cancer pathogenesis.

The Role of Long Noncoding RNAs in Antiestrogen Resistance in Breast Cancer: An Overview and Update

As a standard treatment, endocrine therapy has dramatically enhanced the prognosis of patients with estrogen receptor (ER)-positive breast cancer, which accounts for nearly 70% of all breast cancers. Antiestrogen drugs such as tamoxifen and aromatase inhibitors are the standard treatment options for ERα-positive breast cancer. However, acquired antiestrogen resistance is still the leading cause of disease recurrence and progression. Evidence has shown that long noncoding RNAs (lncRNAs) play an essential role in the development of antiestrogen resistance in ER-positive breast cancer and can serve as biomarkers or potential therapeutic targets. This review highlights the role of lncRNAs in the development of antiestrogen resistance in breast cancer.

Nanotechnology, in silico and endocrine-based strategy for delivering paclitaxel and miRNA: Prospects for the therapeutic management of breast cancer

Breast cancer is one of the most prevalent and reoccurring cancers and the second most common reason of death in women. Despite advancements in therapeutic strategies for breast cancer, early tumor recurrence and metastasis in patients indicate resistance to chemotherapeutic medicines, such as paclitaxel due to the abnormal expression of ER and EGF2 in breast cancer cells. Therefore, the development of alternatives to paclitaxel is urgently needed to overcome challenges involving drug resistance. An increasing number of studies has revealed miRNAs as novel natural alternative substances that play a crucial role in regulating several physiological processes and have a close, adverse association with several diseases, including breast cancer. Due to the therapeutic potential of miRNA and paclitaxel in cancer research, the current review focuses on the differential roles of various miRNAs in breast cancer development and treatment. miRNA delivery to a specific target site, the development of paclitaxel and miRNA formulations, and nanotechnological strategies for the delivery of nanopaclitaxel in the management of breast cancer are discussed. These strategies involve improving the cellular uptake and bioavailability and reducing the toxicity of free paclitaxel to achieve accumulation tumor site. Furthermore, a molecular docking study was performed to ascertain the enhanced anticancer activity of the nanoformulation of ANG1005 and Abraxane. An in silico analysis revealed that ANG1005 and Abraxane nanoformulations have superior and significantly enhanced interactions with the proteins α-tubulin and Bcl-2. Therefore, ANG1005 and Abraxane may be more suitable in the therapeutic management of breast cancer than the existing free paclitaxel. miRNAs can revert abnormal gene expression to normalcy; since miRNAs serve as tumor suppressors. Therefore, restoration of particular miRNAs levels as a replacement therapy may be an effective endocrine potential strategy for treating ER positive/ negative breast cancers.

LINC00346 promotes pancreatic cancer progression through the CTCF-mediated Myc transcription

Although multiple factors are known to contribute to pancreatic ductal adenocarcinoma (PDAC) progression, the role of long non-coding RNAs (lncRNAs) in PDAC remains largely unknown. In this study, we present data that long intergenic non-coding RNA 346 (LINC00346) functions as a promoting factor for PDAC development. We first show that LINC00346 is highly expressed in pancreatic tumor specimens as compared to normal pancreatic tissue based on interrogation of The Cancer Genome Atlas (TCGA) pancreatic adenocarcinoma dataset. Of significance, this upregulation of LINC00346 is associated with overall survival (OS) and disease-free survival (DFS), respectively. We further show that knockout (KO) of LINC00346 impairs pancreatic cancer cell proliferation, tumorigenesis, migration, and invasion ability. Importantly, these phenotypes can be restored by LINC00346 re-expression in KO cells (i.e., rescue experiment). RNA precipitation assays combined with mass spectrometry analysis indicate that LINC00346 interacts with CCCTC-binding factor (CTCF), a known transcriptional repressor of c-Myc. This interaction between LINC00346 and CTCF prevents the binding of CTCF to c-Myc promoter, relieving the CTCF-mediated repression of c-Myc. Thus, LINC00346 functions as a positive transcriptional regulator of c-Myc. Together, these results suggest that LINC00346 contributes to PDAC pathogenesis by activating c-Myc, and as such, LINC00346 may serve as a potential biomarker and therapeutic target for PDAC.

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

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

Molecular Comparison of Imatinib-Naïve and Resistant Gastrointestinal Stromal Tumors: Differentially Expressed microRNAs and mRNAs

Despite the success of imatinib in advanced gastrointestinal stromal tumor (GIST) patients, 50% of the patients experience resistance within two years of treatment underscoring the need to get better insight into the mechanisms conferring imatinib resistance. Here the microRNA and mRNA expression profiles in primary (imatinib-naïve) and imatinib-resistant GIST were examined. Fifty-three GIST samples harboring primary KIT mutations (exon 9; n = 11/exon 11; n = 41/exon 17; n = 1) and comprising imatinib-naïve (IM-n) (n = 33) and imatinib-resistant (IM-r) (n = 20) tumors, were analyzed. The microRNA expression profiles were determined and from a subset (IM-n, n = 14; IM-r, n = 15) the mRNA expression profile was established. Ingenuity pathway analyses were used to unravel biochemical pathways and gene networks in IM-r GIST. Thirty-five differentially expressed miRNAs between IM-n and IM-r GIST samples were identified. Additionally, miRNAs distinguished IM-r samples with and without secondary KIT mutations. Furthermore 352 aberrantly expressed genes were found in IM-r samples. Pathway and network analyses revealed an association of differentially expressed genes with cell cycle progression and cellular proliferation, thereby implicating genes and pathways involved in imatinib resistance in GIST. Differentially expressed miRNAs and mRNAs between IM-n and IM-r GIST were identified. Bioinformatic analyses provided insight into the genes and biochemical pathways involved in imatinib-resistance and highlighted key genes that may be putative treatment targets.

Akt in cancer: Mediator and more

Akt is a serine/threonine kinase and it participates in the key role of the PI3K signaling pathway. The Akt can be activated by a wide range of growth signals and the biochemical mechanisms leading to Akt activation are well defined. Once activated, Akt modulates the function of many downstream proteins involved in cellular survival, proliferation, migration, metabolism, and angiogenesis. The Akt is a central node of many signaling pathways and it is frequently deregulated in many types of human cancers. In this review, we provide an overview of Akt function and its role in the hallmarks of human cancer. We also discussed various mechanisms of Akt dysregulation in cancers, including epigenetic modifications like methylation, post-transcriptional non-coding RNAs-mediated regulation, and the overexpression and mutation.

Gene Expression and miRNAs Profiling: Function and Regulation in Human Epidermal Growth Factor Receptor 2 (HER2)-Positive Breast Cancer

Breast cancer is the second most common cause of cancer-related deaths among women worldwide. It is a heterogeneous disease with four major molecular subtypes. One of the subtypes, human epidermal growth factor receptor 2 (HER2)-enriched (HER2-positive) is characterized by the absence of estrogen and progesterone receptors and overexpression of HER2 receptor, and accounts for 15–20% of all breast cancers. Despite the anti-HER2 and cytotoxic chemotherapy, HER2 subtype is an aggressive disease with significant mortality. Recent advances in molecular biology techniques, including gene expression profiling, proteomics, and microRNA analysis, have been extensively used to explore the underlying mechanisms behind human breast carcinogenesis and metastasis including HER2-positive breast cancer, paving the way for developing new targeted therapies. This review focuses on recent advances on gene expression and miRNA status in HER2-positive breast cancer.

Micromanaging aerobic respiration and glycolysis in cancer cells

BACKGROUND

Cancer cells possess a common metabolic phenotype, rewiring their metabolic pathways from mitochondrial oxidative phosphorylation to aerobic glycolysis and anabolic circuits, to support the energetic and biosynthetic requirements of continuous proliferation and migration. While, over the past decade, molecular and cellular studies have clearly highlighted the association of oncogenes and tumor suppressors with cancer-associated glycolysis, more recent attention has focused on the role of microRNAs (miRNAs) in mediating this metabolic shift. Accumulating studies have connected aberrant expression of miRNAs with direct and indirect regulation of aerobic glycolysis and associated pathways.

SCOPE OF REVIEW

This review discusses the underlying mechanisms of metabolic reprogramming in cancer cells and provides arguments that the earlier paradigm of cancer glycolysis needs to be updated to a broader concept, which involves interconnecting biological pathways that include miRNA-mediated regulation of metabolism. For these reasons and in light of recent knowledge, we illustrate the relationships between metabolic pathways in cancer cells. We further summarize our current understanding of the interplay between miRNAs and these metabolic pathways. This review aims to highlight important metabolism-associated molecular components in the hunt for selective preventive and therapeutic treatments.

MAJOR CONCLUSIONS

Metabolism in cancer cells is influenced by driver mutations but is also regulated by posttranscriptional gene silencing. Understanding the nuanced regulation of gene expression in these cells and distinguishing rapid cellular responses from chronic adaptive mechanisms provides a basis for rational drug design and novel therapeutic strategies.

Estrogen-Mediated MicroRNA-101-3p Expression Represses Hyaluronan Synthase 2 in Synovial Fibroblasts From Idiopathic Condylar Resorption Patients

PURPOSE

Idiopathic condylar resorption (ICR) is an aggressive form of osteoarthritis that is frequently observed in adolescent female patients. We hypothesized that an estrogen-mediated pathway may contribute to ICR development.

MATERIALS AND METHODS

An enzyme-linked immunosorbent assay was used to detect the levels of estradiol (E2) and hyaluronan in synovial fluid. Immunohistochemistry, real-time polymerase chain reaction, and Western blotting were used to detect the expression of microRNAs (miRNAs) and related genes after transfection of miRNA-101-3p mimics, inhibitor, or short interfering RNA into synovial fibroblasts. Dual-luciferase activity was determined to identify the direct effect of miRNA-101-3p on hyaluronan synthase 2 (HAS2). Linear regression analysis, the nonparametric Mann-Whitney U test, the Student t test, and 1-way analysis of variance were carried out to analyze the results of each group.

RESULTS

The relationship between hyaluronan and E2 was negatively correlated in synovial fluid (Pearson r = -0.3179, P = .0230). Among the screened miRNAs, miRNA-101-3p was the most overexpressed in ICR. E2 mostly upregulated the expression of miRNA-101-3p at a dose of 10 nmol/L 12 hours after transfection in synovial fibroblasts of patients with ICR. However, E2 induction of miRNA-101-3p expression was significantly repressed by estrogen receptor α interference (P = 0.0286). The dual-luciferase assay showed that miRNA-101-3p regulated the expression of HAS2 by directly targeting its 3' untranslated region.

CONCLUSIONS

We speculate that E2 regulates HAS2 expression by targeting miRNA-101-3p in synovial fibroblasts of patients with ICR. Thus, the E2-miRNA-101-3p-HAS2 pathway might play an important role in the pathogenesis of ICR.

Endocrine Resistance in Hormone Receptor Positive Breast Cancer-From Mechanism to Therapy

The importance and role of the estrogen receptor (ER) pathway has been well-documented in both breast cancer (BC) development and progression. The treatment of choice in women with metastatic breast cancer (MBC) is classically divided into a variety of endocrine therapies, 3 of the most common being: selective estrogen receptor modulators (SERM), aromatase inhibitors (AI) and selective estrogen receptor down-regulators (SERD). In a proportion of patients, resistance develops to endocrine therapy due to a sophisticated and at times redundant interference, at the molecular level between the ER and growth factor. The progression to endocrine resistance is considered to be a gradual, step-wise process. Several mechanisms have been proposed but thus far none of them can be defined as the complete explanation behind the phenomenon of endocrine resistance. Although multiple cellular, molecular and immune mechanisms have been and are being extensively studied, their individual roles are often poorly understood. In this review, we summarize current progress in our understanding of ER biology and the molecular mechanisms that predispose and determine endocrine resistance in breast cancer patients.

Functional miRNAs in breast cancer drug resistance

Owing to improved early surveillance and advanced therapy strategies, the current death rate due to breast cancer has decreased; nevertheless, drug resistance and relapse remain obstacles on the path to successful systematic treatment. Multiple mechanisms responsible for drug resistance have been elucidated, and miRNAs seem to play a major part in almost every aspect of cancer progression, including tumorigenesis, metastasis, and drug resistance. In recent years, exosomes have emerged as novel modes of intercellular signaling vehicles, initiating cell–cell communication through their fusion with target cell membranes, delivering functional molecules including miRNAs and proteins. This review particularly focuses on enumerating functional miRNAs involved in breast cancer drug resistance as well as their targets and related mechanisms. Subsequently, we discuss the prospects and challenges of miRNA function in drug resistance and highlight valuable approaches for the investigation of the role of exosomal miRNAs in breast cancer progression and drug resistance.

MicroRNA-101 inhibits angiogenesis via COX-2 in endometrial carcinoma

Abnormal angiogenesis is critically involved in tumor progression and metastasis including endometrial cancer and is regulated by microRNAs such as microRNA-101 (miR-101). We hypothesize that miR-101 expression is disrupted in endometrial cancer and modulation of miR-101 levels is sufficient to regulate tumor growth through angiogenesis. We examined the expression levels of miR-101 and factors involved in angiogenesis in the patients with endometrial cancer. We also overexpressed or inhibited miR-101 in RL-95-2 cells and examined their effects on cell toxicity and tumor growth. Finally, we determined if miR-101 regulated tumorigenesis through cyclooxygenase-2 (COX-2). We found that miR-101 levels were significantly reduced. Factors involved in angiogenesis included vascular endothelial growth factor-A (VEGF-A), thrombospondin-1 (TSP-1), cyclooxygenase-2 (COX-2), prostaglandin E2 (PGE2), and aromatase (P450arom), which were increased in endometrial carcinoma. Modulation of miR-101 level was sufficient to affect tumor growth. Finally, we found that the effects of miR-101 inhibition on tumor growth were suppressed by COX-2 inhibition. Our results suggest that modulating miR-101 and COX-2 levels or their activity may be a potential therapeutic strategy for endometrial cancer.

Identification of miRNAs as biomarkers for acquired endocrine resistance in breast cancer

Therapies targeting estrogen receptor α (ERα) including tamoxifen, a selective estrogen receptor modulator (SERM) and aromatase inhibitors (AI), e.g., letrozole, have proven successful in reducing the death rate for breast cancer patients whose initial tumors express ERα. However, about 40% of patients develop acquired resistance to these endocrine treatments. There is a critical need to develop sensitive circulating biomarkers that accurately identify signaling pathways altered in breast cancer patients resistant to endocrine therapies. Serum miRNAs have the potential to serve as biomarkers of the progression of endocrine-resistant breast cancer due to their cancer-specific expression and stability. Exosomal transfer of miRNAs has been implicated in metastasis and endocrine-resistance. This review focuses on miRNAs in breast tumors and in serum, including exosomes, from breast cancer patients that are associated with resistance to tamoxifen since it is best-studied.

Linc-RoR promotes MAPK/ERK signaling and confers estrogen-independent growth of breast cancer

Background

The conversion from estrogen-dependent to estrogen-independent state of ER+ breast cancer cells is the key step to promote resistance to endocrine therapies. Although the crucial role of MAPK/ERK signaling pathway in estrogen-independent breast cancer cell growth is well established, the underlying mechanism is not fully understood.

Methods

In this study, we profiled lncRNA expression against a focused group of lncRNAs selected from lncRNA database. CRISPR/Cas9 was employed to knockout (KO) linc-RoR in MCF-7 cells, while rescue experiments were carried out to re-express linc-RoR in KO cells. Colony formation and MTT assays were used to examine the role of linc-RoR in estrogen-independent growth and tamoxifen resistance. Western blot and qRT-PCR were used to determine the change of protein and lncRNA levels, respectively. The expression of DUSP7 in clinical specimens was downloaded from Oncomine (www.oncomine.org) and the dataset from Kaplan-Meier Plotter (http://kmplot.com) was used to analyze the clinical outcomes in relation to DUSP7.

Results

We identified that linc-RoR functions as an onco-lncRNA to promote estrogen-independent growth of ER+ breast cancer. Under estrogen deprivation, linc-RoR causes the upregulation of phosphorylated MAPK/ERK pathway which in turn activates ER signaling. Knockout of linc-RoR abrogates estrogen deprivation-induced ERK activation as well as ER phosphorylation, whereas re-expression of linc-RoR restores all above phenotypes. Moreover, we show that the ERK-specific phosphatase Dual Specificity Phosphatase 7 (DUSP7), also known as MKP-X, is involved in linc-RoR KO-induced repression of MAPK/ERK signaling. Interestingly, linc-RoR KO increases the protein stability of DUSP7, resulting in repression of ERK phosphorylation. Clinical data analysis reveal that DUSP7 expression is lower in ER+ breast cancer samples than that in ER- breast cancer. Moreover, downregulation of DUSP7 expression is associated with poor patient survival.

Conclusion

Taken together, these results suggest that linc-RoR promotes estrogen-independent growth and activation of MAPK/ERK pathway of breast cancer cells by regulating the ERK-specific phosphatase DUSP7. Thus, this study might help not only in establishing a role for linc-RoR in estrogen-independent and tamoxifen resistance of ER+ breast cancer, but also suggesting a link between linc-RoR and MAPK/ERK pathway.

Electronic supplementary material

The online version of this article (10.1186/s12943-017-0727-3) contains supplementary material, which is available to authorized users.

Low plasma levels of miR-101 are associated with tumor progression in gastric cancer

Background

Several studies have identified the decreased expression of the tumor suppressor miR-101 in various cancers. In this study, we tested miR-101 as a potential therapeutic target and novel plasma biomarker for gastric cancer (GC).

Results

The miR-101 expression level was significantly lower in GC tissues (P = 0.0038) and GC cell lines (P = 0.0238) than in normal gastric mucosa. Both exosomal and plasma miR-101 were significantly downregulated in GC patients compared with healthy volunteers (P = 0.0281 and P < 0.0001, respectively). Low miR-101 plasma level was significantly associated with advanced T factor, advanced disease stage, and peritoneal metastasis and predicted poor prognosis in GC patients (P = 0.0368; hazard ratio, 3.079; 95% confidence interval: 1.06–11.08). Overexpression of miR-101 in GC cells induced apoptosis by inhibiting MCL1 and suppressed cell migration and invasion by regulating ZEB1.

Conclusions

Depletion of the tumor suppressor miRNA-101 in plasma is related to tumor progression and poor outcomes. Low plasma miR-101 may be a biomarker for GC, and its restoration might be a novel anticancer treatment strategy.

Amygdalar expression of the microRNA miR-101a and its target Ezh2 contribute to rodent anxiety-like behaviour

A greater understanding of neural mechanisms contributing to anxiety is needed in order to develop better therapeutic interventions. This study interrogates a novel molecular mechanism that shapes anxiety-like behaviour, demonstrating that the microRNA miR-101a-3p and its target, enhancer of zeste homolog 2 (Ezh2) in the amygdala, contribute to rodent anxiety-like behaviour. We utilized rats that were selectively bred for differences in emotionality and stress reactivity, showing that high-novelty-responding (HR) rats, which display low trait anxiety, have lower miR-101a-3p levels in the amygdala compared to low-novelty-responding (LR) rats that characteristically display high trait anxiety. To determine whether there is a causal relationship between amygdalar miR-101a-3p and anxiety behaviour, we used a viral approach to overexpress miR-101a-3p in the amygdala of HR rats and test whether it would increase their typically low levels of anxiety-like behaviour. We found that increasing miR-101a-3p in the amygdala increased HRs' anxiety-like behaviour in the open-field test and elevated plus maze. Viral-mediated miR-101a-3p overexpression also reduced expression of the histone methyltransferase Ezh2, which mediates gene silencing via trimethylation of histone 3 at lysine 27 (H3K27me3). Knockdown of Ezh2 with short-interfering RNA (siRNA) also increased HRs' anxiety-like behaviour, but to a lesser degree than miR-101a-3p overexpression. Overall, our data demonstrate that increasing miR-101a-3p expression in the amygdala increases anxiety-like behaviour and that this effect is at least partially mediated via repression of Ezh2. This work adds to the growing body of evidence implicating miRNAs and epigenetic regulation as molecular mediators of anxiety behaviour.

Clinical Value of miR-101-3p and Biological Analysis of its Prospective Targets in Breast Cancer: A Study Based on The Cancer Genome Atlas (TCGA) and Bioinformatics

Background

MiR-101-3p can promote apoptosis and inhibit proliferation, invasion, and metastasis in breast cancer (BC) cells. However, its mechanisms in BC are not fully understood. Therefore, a comprehensive analysis of the target genes, pathways, and networks of miR-101-3p in BC is necessary.

Material/Methods

The miR-101 profiles for 781 patients with BC from The Cancer Genome Atlas (TCGA) were analyzed. Gene expression profiling of GSE31397 with miR-101-3p transfected MCF-7 cells and scramble control cells was downloaded from Gene Expression Omnibus (GEO), and the differentially expressed genes (DEGs) were identified. The potential genes targeted by miR-101-3p were also predicted. Gene Ontology (GO) and pathway and network analyses were constructed for the DEGs and predicted genes.

Results

In the TCGA data, a low level of miR-101-2 expression might represent a diagnostic (AUC: 0.63) marker, and the miR-101-1 was a prognostic (HR=1.79) marker. MiR-101-1 was linked to the estrogen receptor (ER), progesterone receptor (PR), and human epidermal growth factor receptor 2 (HER2), and miR-101-2 was associated with the tumor (T), lymph node (N), and metastasis (M) stages of BC. Moreover, 427 genes were selected from the 921 DEGs in GEO and the 7924 potential target genes from the prediction databases. These genes were related to transcription, metabolism, biosynthesis, and proliferation. The results were also significantly enriched in the VEGF, mTOR, focal adhesion, Wnt, and chemokine signaling pathways.

Conclusions

MiR-101-1 and miR-101-2 may be prospective biomarkers for the prognosis and diagnosis of BC, respectively, and are associated with diverse clinical parameters. The target genes of miR-101-3p regulate the development and progression of BC. These results provide insight into the pathogenic mechanism and potential therapies for BC.

ERK-mediated NF-κB activation through ASIC1 in response to acidosis

Acidic microenvironment is a common feature of solid tumors. We have previously shown that neuron specific acid-sensing ion channel 1 (ASIC1) is expressed in breast cancer, and it is responsible for acidosis-induced cellular signaling through AKT, leading to nuclear factor-κB (NF-κB) activation, and cell invasion and metastasis. However, AKT is frequently activated in cancer. Thus, a key question is whether ASIC1-mediated cell signaling still takes place in the cancer cells carrying constitutively active AKT. In the present study, we show that among four prostate cancer cell lines tested, 22Rv1 cells express the highest level of phosphorylated AKT that is not impacted by acidosis. However, acidosis can still induce NF-κB activation during which extracellular signal-regulated kinase (ERK) serves as an alternative pathway for ASIC-mediated cell signaling. Inhibition of ERK by chemical inhibitors or small interfering RNAs suppresses the acidosis-induced NF-κB activity through regulation of the inhibitory subunit IκBα phosphorylation. Furthermore, suppression of ASIC1-mediated generation of reactive oxygen species (ROS) by ROS scavengers, such as glutathione or N-acetyl-cysteine causes a decrease in ERK phosphorylation and degradation of IκBα. Finally, ASIC1 is upregulated in a subset of prostate cancer cases and ASIC1 knockout by CRISPR/Cas9 significantly suppresses cell invasion, and castration resistance both in vitro and in vivo. Together, these results support the significance of ASIC1-ROS-ERK-IκBα-NF-κB axis in prostate tumorigenesis, especially in the constitutively active AKT background.

MicroRNA-101 inhibits cell progression and increases paclitaxel sensitivity by suppressing MCL-1 expression in human triple-negative breast cancer

Triple-negative breast cancer is the most aggressive breast cancer subtype. The aim of our study was to investigate the functional role of both miR-101 and MCL-1 in the sensitivity of human triple-negative breast cancer (TNBC) to paclitaxel. We found that the expression of miR-101 was strongly decreased in triple-negative breast cancer tissues and cell lines. The expression of miR-101 was not associated with clinical stage or lymph node infiltration in TNBC. Ectopic overexpression of miR-101 inhibit growth and induced apoptosis in vitro and suppressed tumorigenicity in vivo. MCL-1 was significantly overexpressed in most of the TNBC tissues and cell lines. Luciferase assay results confirmed MCL-1 as a direct target gene of miR-101. MiR-101 inhibited MCL-1 expression in TNBC cells and transplanted tumors. There was a negative correlation between the level of expression of miR-101 and MCL-1 in TNBC tissues. Suppression of MCL-1 enhanced the sensitivity of MDA-MB-435 cells to paclitaxel. Furthermore, miR-101 increased paclitaxel sensitivity by inhibiting MCL-1 expression. Our findings provide significant insight into the molecular mechanisms of TNBC carcinogenesis and may have clinical relevance for the development of novel, targeted therapies for TNBC.

MicroRNA-101 targets von Hippel-Lindau tumor suppressor (VHL) to induce HIF1α mediated apoptosis and cell cycle arrest in normoxia condition

The activation/inactivation of HIF1α is precisely regulated in an oxygen-dependent manner. HIF1α is essential for hypoxia induced apoptosis and cell cycle arrest. Several recent studies indicated that the expression of miRNAs can be modulated by hypoxia. However, the involvement of miRNAs in the regulation of HIF1α induction remains elusive. In present study, we demonstrated that miR-101 was rapidly and transiently induced after hypoxia in breast cancer cells. Over-expression of miR-101 significantly inhibited cell proliferation in breast cancer cells through increased apoptosis and cell cycle arrest in normoxia condition. This inhibitory phenomenon seems due to miR-101-mediated induction of HIF1α, because we identified that VHL, a negative regulator of HIF1α, is a novel target of miR-101 and over-expression of miR-101 decreased VHL levels and subsequently stabilized HIF1α and induced its downstream target VEGFA. Furthermore, we demonstrated that siRNA-mediated knockdown of VHL or HIF1α overexpression could also induce apoptosis and cell cycle arrest whereas enforced expression of VHL, administration of anti-miR-101 oligos or treatment of 2-MeOE2, an inhibitor of HIF1α, could rescue cells from such inhibition. These results reveal a novel regulatory mechanism of HIF1α induction in normoxia and suggest that miR-101 mediated proliferation inhibition may through HIF1α mediated apoptosis and cell cycle arrest.

Gga-miR-101-3p Plays a Key Role in Mycoplasma gallisepticum (HS Strain) Infection of Chicken

Mycoplasma gallisepticum (MG), one of the most pathogenic Mycoplasma, has caused tremendous economic loss in the poultry industry. Recently, increasing evidence has suggested that micro ribonucleic acids (miRNAs) are involved in microbial pathogenesis. However, little is known about potential roles of miRNAs in MG infection of chicken. In the present study, using miRNA Solexa sequencing we have found that gga-miR-101-3p was up-regulated in the lungs of MG-infected chicken embryos. Moreover, gga-miR-101-3p regulated expression of the host enhancer of zeste homolog 2 (EZH2) through binding to the 3’ un-translated region (3’-UTR) of EZH2 gene. Over-expression of gga-miR-101-3p significantly inhibited EZH2 expression and hence inhibited proliferation of chicken embryonic fibroblast (DF-1 cells) by blocking the G1-to-S phase transition. Similar results were obtained in MG-infected chicken embryos and DF-1 cells, where gga-miR-101-3p was significantly up-regulated, while EZH2 was significantly down-regulated. This study reveals that gga-miR-101-3p plays an important role in MG infection through regulation of EZH2 expression and provides a new insight into the mechanisms of MG pathogenesis.