MicroRNA-regulated gene networks during mammary cell differentiation are associated with breast cancer

Periconceptional and Prenatal Exposure to Metals and Extracellular Vesicle and Particle miRNAs in Human Milk: A Pilot Study

Human milk is a rich source of microRNAs (miRNAs), which can be transported by extracellular vesicles and particles (EVPs) and are hypothesized to contribute to maternal-offspring communication and child development. Environmental contaminant impacts on EVP miRNAs in human milk are largely unknown. In a pilot study of 54 mother-child pairs from the New Hampshire Birth Cohort Study, we examined relationships between five metals (arsenic, lead, manganese, mercury, and selenium) measured in maternal toenail clippings, reflecting exposures during the periconceptional and prenatal periods, and EVP miRNA levels in human milk. 798 miRNAs were profiled using the NanoString nCounter platform; 200 miRNAs were widely detectable and retained for downstream analyses. Metal-miRNA associations were evaluated using covariate-adjusted robust linear regression models. Arsenic exposure during the periconceptional and prenatal periods was associated with lower total miRNA content in human milk EVPs (PBonferroni < 0.05). When evaluating miRNAs individually, 13 miRNAs were inversely associated with arsenic exposure, two in the periconceptional period and 11 in the prenatal period (PBonferroni < 0.05). Other metal-miRNA associations were not statistically significant after multiple testing correction (PBonferroni ≥ 0.05). Many of the arsenic-associated miRNAs are involved in lactation and have anti-inflammatory properties in the intestine and tumor suppressive functions in breast cells. Our findings raise the possibility that periconceptional and prenatal arsenic exposure may reduce levels of multiple miRNAs in human milk EVPs. However, larger confirmatory studies, which can apply environmental mixture approaches, evaluate potential effect modifiers of these relationships, and examine possible downstream consequences for maternal and child health and breastfeeding outcomes, are needed.

MicroRNAs as Molecular Biomarkers for the Characterization of Basal-like Breast Tumor Subtype

Breast cancer is a heterogeneous disease highlighted by the presence of multiple tumor variants and the basal-like breast cancer (BLBC) is considered to be the most aggressive variant with limited therapeutics and a poor prognosis. Though the absence of detectable protein and hormonal receptors as biomarkers hinders early detection, the integration of genomic and transcriptomic profiling led to the identification of additional variants in BLBC. The high-throughput analysis of tissue-specific micro-ribonucleic acids (microRNAs/miRNAs) that are deemed to have a significant role in the development of breast cancer also displayed distinct expression profiles in each subtype of breast cancer and thus emerged to be a robust approach for the precise characterization of the BLBC subtypes. The classification schematic of breast cancer is still a fluid entity that continues to evolve alongside technological advancement, and the transcriptomic profiling of tissue-specific microRNAs is projected to aid in the substratification and diagnosis of the BLBC tumor subtype. In this review, we summarize the current knowledge on breast tumor classification, aim to collect comprehensive evidence based on the microRNA expression profiles, and explore their potential as prospective biomarkers of BLBC.

Inhibiting SETD7 methyl-transferase activity impairs differentiation, lipid metabolism and lactogenesis in mammary epithelial cells

SETD7 (SET7/9, KMT7) is a lysine methyltransferase that targets master regulators of cell proliferation and differentiation. Here, the impact of inhibiting SETD7 catalytic activity on mammary epithelial cell differentiation was studied by focusing on genes associated with epithelial differentiation, lactogenesis, and lipid metabolism in HC11 and EpH4 cell lines. Setd7 mRNA and protein levels were induced upon lactogenic differentiation in both cell lines. Inhibition of SETD7 activity by the compound (R)-PFI-2 increased cell proliferation and downregulated E-cadherin, beta-catenin, lactoferrin, insulin-like growth factor binding protein 5, and beta-casein levels. In addition, inhibition of SETD7 activity affected the lipid profile and altered the mRNA expression of the phospholipid biosynthesis-related genes choline phosphotransferase 1, and ethanolamine-phosphate cytidylyltransferase. Altogether, the results suggest that inhibiting SETD7 catalytic activity impairs mammary epithelial and lactogenic differentiation.

Non-coding RNA-related antitumor mechanisms of marine-derived agents

In the last two decades, natural active substances have attracted great attention in developing new antitumor drugs, especially in the marine environment. A series of marine-derived compounds or derivatives with potential antitumor effects have been discovered and developed, but their mechanisms of action are not well understood. Emerging studies have found that several tumor-related signaling pathways and molecules are involved in the antitumor mechanisms of marine-derived agents, including noncoding RNAs (ncRNAs). In this review, we provide an update on the regulation of marine-derived agents associated with ncRNAs on tumor cell proliferation, apoptosis, cell cycle, invasion, migration, drug sensitivity and resistance. Herein, we also describe recent advances in marine food-derived ncRNAs as antitumor agents that modulate cross-species gene expression. A better understanding of the antitumor mechanisms of marine-derived agents mediated, regulated, or sourced by ncRNAs will provide new biomarkers or targets for potential antitumor drugs from preclinical discovery and development to clinical application.

Regulation of breast cancer metastasis signaling by miRNAs

Despite the decline in death rate from breast cancer and recent advances in targeted therapies and combinations for the treatment of metastatic disease, metastatic breast cancer remains the second leading cause of cancer-associated death in U.S. women. The invasion-metastasis cascade involves a number of steps and multitudes of proteins and signaling molecules. The pathways include invasion, intravasation, circulation, extravasation, infiltration into a distant site to form a metastatic niche, and micrometastasis formation in a new environment. Each of these processes is regulated by changes in gene expression. Noncoding RNAs including microRNAs (miRNAs) are involved in breast cancer tumorigenesis, progression, and metastasis by post-transcriptional regulation of target gene expression. miRNAs can stimulate oncogenesis (oncomiRs), inhibit tumor growth (tumor suppressors or miRsupps), and regulate gene targets in metastasis (metastamiRs). The goal of this review is to summarize some of the key miRNAs that regulate genes and pathways involved in metastatic breast cancer with an emphasis on estrogen receptor α (ERα+) breast cancer. We reviewed the identity, regulation, human breast tumor expression, and reported prognostic significance of miRNAs that have been documented to directly target key genes in pathways, including epithelial-to-mesenchymal transition (EMT) contributing to the metastatic cascade. We critically evaluated the evidence for metastamiRs and their targets and miRNA regulation of metastasis suppressor genes in breast cancer progression and metastasis. It is clear that our understanding of miRNA regulation of targets in metastasis is incomplete.

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

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

MicroRNA-based potential diagnostic, prognostic and therapeutic applications in triple-negative breast cancer

Triple-negative breast cancer (TNBC) is a distinct subtype of breast cancer characterized by high recurrence rates and poor prognosis compared to other breast cancers. MicroRNAs (miRNAs) are small non-coding RNAs that regulate the expression of various post-transcriptional gene and silence a broad set of target genes. Many recent studies have demonstrated that miRNAs play an important role in the initiation, promotion, malignant conversion, progression, and metastasis of TNBC. Therefore, the aim of this review is to focus on recent advancements of microRNAs-based potential applications in diagnosis, treatment and prognosis of triple-negative breast cancer.

A miR-206 regulated gene landscape enhances mammary epithelial differentiation

miR‐206 is known to suppress breast cancer. However, while it is expressed in mammary stem cells, its function in such nontumor cells is not well understood. Here, we explore the role of miR‐206 in undifferentiated, stem‐like mammary cells using the murine mammary differentiation model HC11, genome‐wide gene expression analysis, and functional assays. We describe the miR‐206‐regulated gene landscape and propose a network whereby miR‐206 suppresses tumor development. We functionally demonstrate that miR‐206 in nontumor stem‐like cells induces a G1–S cell cycle arrest, and reduces colony formation and epithelial‐to‐mesenchymal transition markers. Finally, we show that addition of miR‐206 accelerates the mammary differentiation process along with related accumulation of lipids. We conclude that miR‐206 impacts a network of signaling pathways, and acts as a regulator of proliferation, stemness, and mammary cell differentiation in nontumor stem‐like mammary cells. Our study provides a broad insight into the breast cancer suppressive functions of miR‐206.

Expression Levels of microRNAs miR-93 and miR-200a in Pancreatic Adenocarcinoma with Special Reference to Differentiation and Relapse-Free Survival

OBJECTIVES

Protein levels of the transcription factor nuclear factor erythroid-derived 2-like 2 (Nrf2) and its inhibitor Kelch-like ECH-associated protein 1 (Keap1) have been proposed as prognostic factors in pancreatic ductal adenocarcinomas (PDACs). These cellular redox-state-regulating enzymes are targeted by several microRNAs, including miR-93 and miR-200a.

METHODS

We assessed mRNA levels of Nrf2 and Keap1 and tissue expression of miR-93 and miR-200a in 51 patients with surgically treated PDAC. Expression levels were separately measured in malignant cells and adjacent benign cells.

RESULTS

Keap1 and Nrf2 mRNA expression levels in cancer cells were lower than in adjacent benign tissue (Wilcoxon's test; p = 0.0015 and p = 0.000032, respectively). Conversely, miR-93 expression was higher in cancer cells than in adjacent benign tissue (p = 0.00082). Low levels of miR-93 and miR-200a in cancer cells were associated with poorer differentiation (p = 0.004 and p = 0.002, respectively). In univariate survival analysis, benign-tissue levels of miR-200a above the median predicted better relapse-free survival (RFS) (p = 0.045).

CONCLUSIONS

High miR-93 and miR-200a levels in cancer cells of PDAC were associated with better differentiation, and miR-200a expression in benign tissue with excellent RFS. Keap1 and Nrf2 mRNA levels showed prominent down-regulation in cancerous versus benign tissue, but they were not associated with disease aggressiveness or outcome.

Association of miR-1247-5p expression with clinicopathological parameters and prognosis in breast cancer

Our study aimed to clarify the correlation between miR‐1247‐5p expression and clinicopathological parameters and survival of patients with breast cancer (BC). We evaluated the expression level of miR‐1247‐5p in 224 formalin‐fixed, paraffin‐embedded specimens (112 BC and matched cancer free tissues) by quantitative real‐time reverse transcriptase polymerase chain reaction (qRT‐PCR). miR‐1247‐5p expression in BC tissues was found to be decreased compared with matched normal tissues (P < 0.01). Additionally, low miR‐1247‐5p expression in BC tissues was significantly associated with the advanced TNM stage (P = 0.007), lymph node metastasis (P = 0.015), poorer pathological differentiation (P = 0.005) and molecular subtype (P = 0.027). The patients in the low miR‐1247‐5p group had a shorter disease‐free survival and overall survival than those in the high miR‐1247‐5p group (P < 0.01). Furthermore, the univariate and the multivariate analyses showed that miR‐1247‐5p expression was an independent predictor of overall survival (P < 0.01). Our study showed that miR‐1247‐5p was related to the biological behaviour of breast tumour and prognosis of patients with BC. miR‐1247‐5p could be a novel tumour suppressor and act as a potential biomarker and therapeutic agent for breast carcinoma.

Effects of miRNAs on functions of breast cancer stem cells and treatment of breast cancer

Breast cancer is one of the most common malignancies for women, which accounts for 30% of all female malignancies. The formation of breast cancer stem cells (BCSCs) is attributed to the acquisition of stemness of tumor cells. With self-renewal potential, these stem cells are insensitive to either radiotherapy or chemotherapy but are significant in regulating tumor behaviors and drug resistance. MicroRNA (miRNA) is a kind of noncoding small RNA for negatively regulating gene expressions. Research findings suggest that many miRNAs specifically regulate the expression of target genes and signal pathways of BCSCs. They play an important role in self-renewal, growth, and metastasis of breast cancer cells as potential targets for treating breast cancer. These signal pathways include phosphatase and tensin homolog deleted on chromosome 10-phosphatidylinositol 3-kinase/Akt, Wnt/β-catenin, Notch, and so on. This paper reviews the progress of research about miRNAs in self-renewal, metastasis, epithelial-mesenchymal transition and metastasis, mediation of resistance to chemotherapies, and treatment of breast cancer.

miR-302b inhibits tumorigenesis by targeting EphA2 via Wnt/ β-catenin/EMT signaling cascade in gastric cancer

Background

EphA2 is a crucial oncogene in gastric cancer (GC) development and metastasis, this study aims to identify microRNAs that target it and serve as key regulators of gastric carcinogenesis.

Methods

We identified several potential microRNAs targeting EphA2 by bioinformatics websites and then analyzed the role of miR-302b in modulating EphA2 in vitro and in vivo of GC, and it’s mechanism.

Results

Our analysis identified miR-302b, a novel regulator of EphA2, as one of the most significantly downregulated microRNA (miRNA) in GC tissues. Overexpression of miR-302b impaired GC cell migratory and invasive properties robustly and suppressed cell proliferation by arresting cells at G0–G1 phase in vitro. miR-302b exhibited anti-tumor activity by reversing EphA2 regulation, which relayed a signaling transduction cascade that attenuated the functions of N-cadherin, β-catenin, and Snail (markers of Wnt/β-catenin and epithelial-mesenchymal transition, EMT). This modulation of EphA2 also had distinct effects on cell proliferation and migration in GC in vivo.

Conclusions

miR-302b serves as a critical suppressor of GC cell tumorigenesis and metastasis by targeting the EphA2/Wnt/β-catenin/EMT pathway.

Electronic supplementary material

The online version of this article (10.1186/s12885-017-3875-3) contains supplementary material, which is available to authorized users.

Differential expression and androgen regulation of microRNAs and metalloprotease 13 in breast cancer cells

MicroRNA molecules (miRNAs) play important roles in regulating cell behavior. The expression of certain miRNAs has been shown to be regulated by the androgen receptor (AR), which seems to have a critical role in the tumorigenic process of breast cancer. The differential expression of 84 miRNAs was first examined in three breast cancer cell lines: the luminal MCF-7 and T47D cells and the molecular apocrine MDA-MB-453 cells. Analysis of basal expression of miRNAs revealed that each cell line had distinct miRNA expression where let-7a and -7b were markers of MDA-MB-453 cells, whereas miR-205 was a marker for the luminal cell lines. Treating the cells with the AR agonist, CI-4AS-1, resulted in unique alterations in the expression of specific miRNA among the three cell lines. Particularly, the expression of miR-100 and miR-125 was reduced in MDA-MB-453 cells by five and three folds, respectively. This effect was simultaneous with AR-induced increase in the expression and extracellular release of metalloprotease-13 (MMP13). Transfection of cells with either miR-100 or miR-125b negated the induction of MMP13 release. Additionally, AR activation induced a morphological alteration of MDA-MB-453 cells, which was blocked by miR-125b only. Collectively, these data indicate that AR may control the biological behavior of breast cancer cells and protein expression via miRNAs.

Co-Expression Network and Pathway Analyses Reveal Important Modules of miRNAs Regulating Milk Yield and Component Traits

Co-expression network analyses provide insights into the molecular interactions underlying complex traits and diseases. In this study, co-expression network analysis was performed to detect expression patterns (modules or clusters) of microRNAs (miRNAs) during lactation, and to identify miRNA regulatory mechanisms for milk yield and component traits (fat, protein, somatic cell count (SCC), lactose, and milk urea nitrogen (MUN)) via miRNA target gene enrichment analysis. miRNA expression (713 miRNAs), and milk yield and components (Fat%, Protein%, lactose, SCC, MUN) data of nine cows at each of six different time points (day 30 (D30), D70, D130, D170, D230 and D290) of an entire lactation curve were used. Four modules or clusters (GREEN, BLUE, RED and TURQUOISE) of miRNAs were identified as important for milk yield and component traits. The GREEN and BLUE modules were significantly correlated (|r| > 0.5) with milk yield and lactose, respectively. The RED and TURQUOISE modules were significantly correlated (|r| > 0.5) with both SCC and lactose. In the GREEN module, three abundantly expressed miRNAs (miR-148a, miR-186 and miR-200a) were most significantly correlated to milk yield, and are probably the most important miRNAs for this trait. DDR1 and DDHX1 are hub genes for miRNA regulatory networks controlling milk yield, while HHEX is an important transcription regulator for these networks. miR-18a, miR-221/222 cluster, and transcription factors HOXA7, and NOTCH 3 and 4, are important for the regulation of lactose. miR-142, miR-146a, and miR-EIA17-14144 (a novel miRNA), and transcription factors in the SMAD family and MYB, are important for the regulation of SCC. Important signaling pathways enriched for target genes of miRNAs of significant modules, included protein kinase A and PTEN signaling for milk yield, eNOS and Noth signaling for lactose, and TGF β, HIPPO, Wnt/β-catenin and cell cycle signaling for SCC. Relevant enriched gene ontology (GO)-terms related to milk and mammary gland traits included cell differentiation, G-protein coupled receptor activity, and intracellular signaling transduction. Overall, this study uncovered regulatory networks in which miRNAs interacted with each other to regulate lactation traits.

The microRNAs miR-200b-3p and miR-429-5p target the LIMK1/CFL1 pathway to inhibit growth and motility of breast cancer cells

Triple-negative breast cancer (TNBC) has the worst prognosis of all subtypes of breast cancer (BC), with limited options for conventional therapy and no targeted therapies. MicroRNAs (miRNAs) are small noncoding RNAs that negatively regulate gene expression. In this study, we aimed to determine whether two members of the miR-200 family, miR-200b-3p and miR-429-5p, are involved in BC cell proliferation and motility and to elucidate their target genes and pathways. We performed a meta-analysis that reveals down-regulated expression of miR-200b-3p and miR-429-5p in BC tissues and cell lines, consistent with a lower expression of miR-200b-3p and miR-429-5p in MDA-MB-231 and HCC1937 cells than in MCF-7 and MCF-10 cells. Overexpression of miR-200b-3p and miR-429-5p significantly inhibited the proliferation, migration, and invasion of TNBC cells; suppressed the expression of markers for proliferation and metastasis in TNBC cells. We next demonstrated that LIM domain kinase 1 (LIMK1) is a direct target gene of miR-200b-3p and miR-429-5p. Inhibition of LIMK1 reduced the expression and phosphorylation of cofilin 1 (CFL1), which polymerizes and depolymerizes F-actin and G-actin to reorganize cellular actin cytoskeleton. In addition, transfection with mimics for miR-200b-3p and miR-429-5p arrested G2/M and G0/G1 cell cycles respectively, suppressed the expression of the cell cycle–related complexes, cyclin D1/CDK4/CDK6 and cyclin E1/CDK2, in TNBC cells. In conclusion, miR-200b-3p and miR-429-5p suppress proliferation, migration, and invasion in TNBC cells, via the LIMK1/CFL1 pathway. These results provide insight into how specific miRNAs regulate TNBC progression and suggest that the LIMK1/CFL1 pathway is a therapeutic target for treating TNBC.

Members of the microRNA-200 family are promising therapeutic targets in cancer

MicroRNAs (miRs) are non-coding, single-stranded RNA molecules that regulate gene expression at the posttranscriptional level. Abnormal expression of miR may result in pathophysiological processes occurring that stimulate the development of various diseases. miRs are commonly dysregulated in cancer and may act as either oncogenes or tumor suppressors. Studies have indicated that members of the miR-200 family are involved in different aspects of cancer biology, including the epithelial-to-mesenchymal transition, tumor angiogenesis and chemoresistance by targeting and repressing the expression of several key messenger RNAs. The present review aims to summarize the role of the miR-200 family and its potential mechanism of action in tumor progression, which may advance the development of novel therapeutic drugs against tumor metastasis in clinical cancer treatment.

miR-148a Suppresses estrogen-induced viability and migration of breast cancer cells via inhibition of estrogen receptor α expression

MicroRNAs (miRs) play critical roles in the development and malignant progression of human cancers. miR-148a has previously been found to inhibit the migration and invasion of breast cancer cells. However, the underlying mechanism of miR-148a in regulating the viability and migration of estrogen receptor (ER) α-positive breast cancer cells is still unknown. In this study, ERα-positive breast cancer MCF7 cells were treated with estradiol (E2). Data from MTT and wound healing assays showed that E2 treatment promoted the viability and migration of MCF7 cells. A bioinformatics analysis and luciferase reporter assay identified ERα as a direct target of miR-148a. Ectopic expression of miR-148a significantly decreased the protein expression of ERα (P<0.01), while knockdown of miR-148a significantly increased the ERα protein level in MCF7 cells (P<0.01). Furthermore, miR-148a overexpression significantly inhibited the E2-induced viability and migration of MCF7 cells (P<0.01), similar to the effect of silencing ERα. However, overexpression of ERα rescued the suppressed viability and migration caused by miR-148a upregulation. Finally, it was found that E2 treatment led to a significant decrease in the miR-148a level in MCF7 cells (P<0.01). These results suggest that miR-148a can suppress the E2-induced viability and migration of MCF7 breast cancer cells via inhibition of ERα protein expression, expanding the understanding of miR function in ERα-positive breast cancer.

Dysregulation of EGFR Pathway in EphA2 Cell Subpopulation Significantly Associates with Poor Prognosis in Colorectal Cancer

PURPOSE

EphA2 receptor is involved in multiple cross-talks with other cellular networks, including EGFR, FAK, and VEGF pathways, with which it collaborates to stimulate cell migration, invasion, and metastasis. Colorectal cancer (CRC) EphA2 overexpression has also been correlated to stem-like properties of cells and tumor malignancy. We investigated the molecular cross-talk and miRNAs modulation of the EphA2 and EGFR pathways. We also explored the role of EphA2/EGFR pathway mediators as prognostic factors or predictors of cetuximab benefit in patients with CRC.

EXPERIMENTAL DESIGN

Gene expression analysis was performed in EphA2_high cells isolated from CRC of the AOM/DSS murine model by FACS-assisted procedures. Six independent cohorts of patients were stratified by EphA2 expression to determine the potential prognostic role of a EphA2/EGFR signature and its effect on cetuximab treatment response.

RESULTS

We identified a gene expression pattern (EphA2, Efna1, Egfr, Ptpn12, and Atf2) reflecting the activation of EphA2 and EGFR pathways and a coherent dysregulation of mir-26b and mir-200a. Such a pattern showed prognostic significance in patients with stage I-III CRC, in both univariate and multivariate analysis. In patients with stage IV and WT KRAS, EphA2/Efna1/Egfr gene expression status was significantly associated with poor response to cetuximab treatment. Furthermore, EphA2 and EGFR overexpression showed a combined effect relative to cetuximab resistance, independently from KRAS mutation status.

CONCLUSIONS

These results suggest that EphA2/Efna1/Egfr genes, linked to a possible control by miR-200a and miR-26b, could be proposed as novel CRC prognostic biomarkers. Moreover, EphA2 could be linked to a mechanism of resistance to cetuximab alternative to KRAS mutations. Clin Cancer Res; 23(1); 159-70. ©2016 AACR.

The prognostic impact of soluble and vesicular HLA-G and its relationship to circulating tumor cells in neoadjuvant treated breast cancer patients

The non-classical human leukocyte antigen G (HLA-G) molecule and its soluble forms exert multiple immune suppressive regulatory functions in malignancy and in stem cells contributing to immune escape mechanisms. HLA-G can be secreted as free soluble HLA-G molecules or via extracellular vesicles (EVs). Here we evaluated these soluble HLA-G forms as prognostic marker for prediction of the clinical outcome of neoadjuvant chemotherapy (NACT) treated breast cancer (BC) patients. Plasma samples of BC patients procured before (n=142) and after (n=154) NACT were quantified for total soluble HLA-G (sHLA-Gtot) and HLA-G levels in ExoQuick™ derived EV fractions (sHLA-GEV) by ELISA. The corresponding increments were specified as free sHLA-G (sHLA-Gfree). Total and free sHLA-G were significantly increased in NACT treated BC patients compared to healthy controls (n=16). High sHLA-Gfree levels were exclusively associated to estrogen receptor expression before NACT. Importantly, high sHLA-GEV levels before NACT were related to disease progression and the detection of stem cell-like circulating tumor cells, but high sHLA-Gfree levels indicated an improved clinical outcome. Thus, this study demonstrates for the first time that the different sHLA-G subcomponents represent dissimilar qualitative prognostic impacts on the clinical outcome of NACT treated BC patients, whereas the total sHLA-G levels without separating into subcomponents are not related to clinical outcome.

MicroRNA-148a represents an independent prognostic marker in bladder cancer

A previous study has demonstrated the roles of microRNA-148a (miR-148a) on apoptosis of bladder cancer cells. The goal of this study was to investigate whether the miR-148a expression level could serve as a new biomarker for the prognosis of bladder cancer patients. We collected a total of 126 bladder cancer samples. The expression level of miR-148a was determined with quantitative real-time polymerase chain reaction (qRT-PCR). Kaplan-Meier method was used to analyze the overall survival. Cox regression analysis was further used to identify prognostic factors. The expression levels of miR-148a in bladder cancer tissues were identified (1.5 ± 0.3; P < 0.001). The bladder cancer patients in the low-expression group more frequently had a high tumor grade (P = 0.025), increased tumor recurrence (P = 0.002), and advanced lymph node (LN) metastasis (P = 0.001). Patient survival analysis revealed a clear positive correlation between miR-148a expression level and survival time of bladder cancer patients (P = 0.005, log-rank = 7.714). In univariate Cox proportional hazards regression analysis, we found that a low-expression level of miR-148a (P = 0.018), tumor grade (P = 0.006), lymph node metastasis (P = 0.001), and recurrence (P < 0.001) were associated with the prognosis of bladder cancer. In multivariate analysis, we found that miR-148a expression (RR = 0.206, 95 % CI 0.095-0.813, P = 0.029), tumor grade (RR = 0.714, 95 % CI 0.224-0.958, P = 0.714), lymph node metastasis (RR = 6.604, 95 % CI 3.192-12.547, P < 0.001), and recurrence (RR = 15.126, 95 % CI 6.714-22.025, P < 0.001) retained significance as an independent prognostic factor of bladder cancer survival (Table 3). All results have showed that miR-148a expression was decreased in bladder cancer specimens and reduced miR-148a expression was associated with poorer survival time, indicating that miR-148a may become a candidate factor for predicting the prognosis of bladder cancer.

Down-Regulation of miR-148a Promotes Metastasis by DNA Methylation and is Associated with Prognosis of Skin Cancer by Targeting TGIF2

BACKGROUND MicroRNAs (miRNA) dysregulation has been considered to be significantly related to the occurrence and development of cancers. Several studies had proved that DNA methylation is an important cause of the abnormal expression of miRNAs. The purpose of this study was to investigate the methylation status of miR-148a and its effects on the metastasis and prognosis of skin cancer, as well as the interaction with TGIF2 gene. MATERIAL AND METHODS According to the qRT-PCR analysis, the expression of miR-148a was down-regulated in tumor tissues compared with the adjacent tissues and healthy controls (P<0.05). In vitro cell metastasis assay revealed that miR-148a could inhibit cell metastasis and its down-regulation promoted metastasis. Luciferase reporter assay found that TGIF2 gene was a target gene and its expression was suppressed by miR-148a in skin cancer. RESULTS Methylation-specific PCR demonstrated that DNA methylation rate of miR-148a was higher in tumor tissues than in adjacent tissues and healthy tissues (P<0.05). miR-148a expression was proved to be epigenetically regulated after the demethylation of it by 5-aza-20-deoxycytidine treatment and qRT-PCR analysis. miR-148a methylation was significantly influenced by many clinicopathologic characteristics such as age (P=0.000), pathological differentiation (P=0.000), and lymph node metastasis (P=0.000). Besides, Kaplan-Meier analysis showed patients with miR-148a methylation lived shorter than those without that (P<0.001). Cox regression analysis manifested that miR-148a methylation (HR=0.053, 95CI%=0.005-0.548, P=0.014) could be serve as an independent prognostic marker for skin cancer. CONCLUSIONS Taken together, the expression of miR-148a was regulated by DNA methylation and targeted by TGIF2. Its methylation may be a potential prognostic indicator in skin cancer.

MiRNAs and Other Epigenetic Changes as Biomarkers in Triple Negative Breast Cancer

Triple negative breast cancer (TNBC) is characterised by the lack of receptors for estrogen (ER), progesterone (PR), and human epidermal growth factor 2 (HER2). Since it cannot be treated by current endocrine therapies which target these receptors and due to its aggressive nature, it has one of the worst prognoses of all breast cancer subtypes. The only treatments remain chemo- and/or radio-therapy and surgery and because of this, novel biomarkers or treatment targets are urgently required to improve disease outcomes. MicroRNAs represent an attractive candidate for targeted therapies against TNBC, due to their natural ability to act as antisense interactors and regulators of entire gene sets involved in malignancy and their superiority over mRNA profiling to accurately classify disease. Here we review the current knowledge regarding miRNAs as biomarkers in TNBC and their potential use as therapeutic targets in this disease. Further, we review other epigenetic changes and interactions of these changes with microRNAs in this breast cancer subtype, which may lead to the discovery of new treatment targets for TNBC.

The role of miRNAs in bone metastasis and their significance in the detection of bone metastasis: a review of the published data

The preferential metastasis of cancer cells to bone disrupts the process of bone remodeling and results in serious complications. Although bone imaging techniques are well established for bone metastasis diagnosis, they still have limits. Recently, small noncoding RNA molecules, called miRNAs, have become the subject of interest in many molecular pathways in relation to bone metastasis. Furthermore, studies have demonstrated the ability to distinguish normal from cancerous cells and metastatic bone tumor origin based on miRNA profiles. Here, we summarize the data on mechanisms of osteolytic and osteoblastic bone metastases supporting the involvement of miRNA changes in the bone metastatic evolution. We also focus on the available evidence regarding current clinical studies of miRNA expression in the detection of bone metastases.

MicroRNA-148a inhibits migration of breast cancer cells by targeting MMP-13

Breast cancer is a threat to the health of women, and metastasis of breast cancer cells plays an important role in the deterioration of breast cancer. MicroRNAs play a critical role in the tumorigenesis and development of breast cancer. MicroRNA-148a (miR-148a) is associated with the growth and metastasis of tumor cells. In the present study, we investigated the role of miR-148a in migration of breast cancer cells as well as the underlying mechanism. MiR-148a was found to inhibit the proliferation and migration of breast cancer cells. To further explore the mechanism through which miR-148a plays its antitumor role, matrix metalloproteinase-13 (MMP-13) was identified as a target of miR-148a by western blot and luciferase reporter assay. Moreover, silence of MMP-13 mimicked the effect of miR-148a, whereas overexpression of MMP-13 rescued the impaired migration caused by miR-148a. Our study demonstrates that miR-148a inhibits the migration of breast cancer cells by targeting MMP-13 and also lays theoretical foundation for further exploration for the function of miR-148a.

miR-200a inhibits migration of triple-negative breast cancer cells through direct repression of the EPHA2 oncogene

Triple-negative breast cancer (TNBC) is characterized by aggressiveness and affects 10-20% of breast cancer patients. Since TNBC lacks expression of ERα, PR and HER2, existing targeted treatments are not effective and the survival is poor. In this study, we demonstrate that the tumor suppressor microRNA miR-200a directly regulates the oncogene EPH receptor A2 (EPHA2) and modulates TNBC migration. We show that EPHA2 expression is correlated with poor survival specifically in basal-like breast cancer and that its expression is repressed by miR-200a through direct interaction with the 3'UTR of EPHA2. This regulation subsequently affects the downstream activation of AMP-activated protein kinase (AMPK) and results in decreased cell migration of TNBC. We establish that miR-200a directs cell migration in a dual manner; in addition to regulating the well-characterized E-cadherin pathway it also regulates a EPHA2 pathway. The miR-200a-EPHA2 axis is a novel mechanism highlighting the possibility of utilizing miR-200a delivery to target TNBC metastases.

Stromal miR-200s contribute to breast cancer cell invasion through CAF activation and ECM remodeling

The activation of cancer-associated fibroblasts (CAFs) is a key event in tumor progression, and alternative extracellular matrix (ECM) proteins derived from CAFs induce ECM remodeling and cancer cell invasion. Here we found that miR-200 s, which are generally downregulated in activated CAFs in breast cancer tissues and in normal fibroblasts (NFs) activated by breast cancer cells, are direct mediators of NF reprogramming into CAFs and of ECM remodeling. NFs with downregulated miR-200 s displayed the traits of activated CAFs, including accelerated migration and invasion. Ectopic expression of miR-200 s in CAFs at least partially restored the phenotypes of NFs. CAF activation may be governed by the targets of miR-200 s, Fli-1 and TCF12, which are responsible for cell development and differentiation; Fli-1 and TCF12 were obviously elevated in CAFs. Furthermore, miR-200 s and their targets influenced collagen contraction by CAFs. The upregulation of fibronectin and lysyl oxidase directly by miR-200 or indirectly through Fli-1 or TCF12 contributed to ECM remodeling, triggering the invasion and metastasis of breast cancer cells both in vitro and vivo. Thus, these data provide important and novel insights into breast CAF activation and ECM remodeling, which trigger tumor cell invasion.

Can microRNA profiling in maternal blood identify women at risk for preterm birth?

OBJECTIVE

MicroRNAs (miRNAs), which are highly conserved single-stranded noncoding RNAs that play a crucial role in gene regulation, have now been identified as important players in many diseases states. MiRNAs have also been demonstrated to be reliable and useful biomarkers to identify those women who are at risk for specific adverse outcomes. The objective of this study was to determine whether miRNA profiles in maternal blood are different in women who are destined to have a preterm, compared with a term, birth.

STUDY DESIGN

A nested case-control study was performed with maternal serum that was collected as part of a larger prospective cohort. MiRNA expression profiles in maternal serum were compared between women who ultimately had a preterm birth (n = 40) compared with term birth (n = 40). MiRNA expression profiles were created with the use of the Affymetrix GeneChip miRNA Array. The data were analyzed with the significance of analysis of microarrays and principle components analyses. A false discovery rate of 20% was used to determine the most differentially expressed miRNAs.

RESULTS

Of the 5640 miRNAs that were analyzed on the array, 4 miRNAs were significantly different between cases and control subjects. Two of the 4 miRNAs were mature miRNAs. The fold difference in expression was <2 for all 4 miRNAs.

CONCLUSION

MiRNA profiles in maternal blood were not significantly different in women who were destined to have a preterm, compared with a term, birth. MiRNAs in maternal blood are unlikely to become clinically useful biomarkers for the prediction of preterm birth.

Interplay between microRNAs and WNT/β-catenin signalling pathway regulates epithelial-mesenchymal transition in cancer

The WNT/β-catenin signalling implies its significance in maintaining an epithelial cell phenotype, proper cell-cell junctions, and tissue homeostasis. Dysregulation of the members of this pathway involves in the development of cancer and an epithelial-mesenchymal transition (EMT) required for metastasis. Loss of E-cadherin is the major contributor to an EMT process and is largely influenced by the WNT/β-catenin signalling. An E-cadherin/β-catenin complex maintains epithelial integrity and disturbance of this complex and WNT/β-catenin pathway will ultimately lead to the nuclear translocation of β-catenin and transcription of EMT-promoting genes. WNT/β-catenin signalling is controlled by microRNAs (miRNAs), several of which are either up- or downregulated during EMT. The strong association between the expression of the WNT signalling components with miRNAs in the initiation and achievement of an EMT phenotype is suggestive of introducing these miRNAs as therapeutic targets against metastatic tumours. Therefore, this review aims to describe these putative miRNAs in altering the WNT/β-catenin signalling in EMT, and whether targeting them is a useful therapeutic option for human invasive tumours.

Ovarian stem cells: From basic to clinical applications

The field of reproductive biology has undergone significant developments in the last decade. The notion that there is a fixed reserve pool of oocytes before birth was established by Zuckerman in 1951. However, in 2004, an article published in nature challenged this central dogma of mammalian reproductive biology. Tilly’s group reported the existence of ovarian germline stem cells (GSCs) in postnatal ovaries of mice and suggested that the bone marrow could be an extragonadal source of ovarian GSCs. These findings were strongly criticized; however, several independent groups have since successfully isolated and characterized ovarian GSCs in postnatal mice. The ovarian GSCs are located in the ovarian surface epithelium and express markers of undifferentiated GSCs. When transplanted into mouse ovaries, mouse ovarian GSCs could differentiate and produce embryos and offspring. Similarly, in a recent study, ovarian GSCs were found to be present in the ovaries of women of reproductive age. Conversely, there is increasing evidence that stem cells responsible for maintaining a healthy state in normal tissue may be a source of some cancers, including ovarian cancer. Cancer stem cells (CSCs) have been found in many tissues, including ovaries. Some researchers have suggested that ovarian cancer may be a result of the transformation and dysfunction of ovarian GSCs with self-renewal properties. Drug resistant and metastasis-generating CSCs are responsible for many important problems affecting ovarian cancer patients. Therefore, the identification of CSCs will provide opportunities for the development of new therapeutic strategies for treatments for infertility and ovarian cancer. In this article, we summarize the current understanding of ovarian GSCs in adult mammals, and we also discuss whether there is a relationship between GSCs and CSCs.

miR-148a dependent apoptosis of bladder cancer cells is mediated in part by the epigenetic modifier DNMT1

Urothelial cell carcinoma of the bladder (UCCB) is the most common form of bladder cancer and it is estimated that ~15,000 people in the United States succumbed to this disease in 2013. Bladder cancer treatment options are limited and research to understand the molecular mechanisms of this disease is needed to design novel therapeutic strategies. Recent studies have shown that microRNAs play pivotal roles in the progression of cancer. miR-148a has been shown to serve as a tumor suppressor in cancers of the prostate, colon, and liver, but its role in bladder cancer has never been elucidated. Here we show that miR-148a is down-regulated in UCCB cell lines. We demonstrate that overexpression of miR-148a leads to reduced cell viability through an increase in apoptosis rather than an inhibition of proliferation. We additionally show that miR-148a exerts this effect partially by attenuating expression of DNA methyltransferase 1 (DNMT1). Finally, our studies demonstrate that treating cells with both miR-148a and either cisplatin or doxorubicin is either additive or synergistic in causing apoptosis. These data taken together suggest that miR-148a is a tumor suppressor in UCCB and could potentially serve as a novel therapeutic for this malignancy.

MicroRNAs-mediated cell fate in triple negative breast cancers

MicroRNAs (miRNAs) are small non-coding RNAs that function as major modulators of posttranscriptional protein-coding gene expression in diverse biological processes including cell survival, cell cycle arrest, senescence, autophagy, and differentiation. The control of miRNAs plays an important role in cancer initiation and metastasis. Triple negative breast cancer (TNBC) is a distinct breast cancer subtype, which is defined by the absence of estrogen receptor (ER), progesterone receptor (PR) and epidermal growth factor receptor 2 (HER2/neu). Due to its high recurrence rate and poor prognosis, TNBC represents a challenge for breast cancer therapy. In recent years, a large number of microRNAs have been identified to play a crucial role in TNBC and some of them were found to be correlated with worse prognosis of TNBC. Thus, understanding the novel function of miRNAs may allow us to develop promising therapeutic targets for the treatment of TNBC patients.

Interleukin-23 promotes the epithelial-mesenchymal transition of oesophageal carcinoma cells via the Wnt/β-catenin pathway

As the eighth most common malignant tumour worldwide, oesophageal cancer (OC) is often diagnosed during the metastasis of its advanced stage. Interleukin (IL)-23 is an immunomodulatory cytokine that has recently been identified as a cancer-associated factor. However, the role of IL-23 in the evolution of OC remains unclear. In the present study, we found that IL-23 was significantly expressed in the tumours of OC patients suffering metastasis and demonstrated that IL-23 contributed to epithelial-mesenchymal transition (EMT) through the Wnt/β-catenin pathway, promoting the migration and invasion of OC cells. In conclusion, IL-23 plays a pivotal role in the development of OC via EMT.

Screening for characteristic microRNAs between pre-invasive and invasive stages of cervical cancer

The aim of the present study was to investigate the characteristic microRNAs (miRNAs) expressed during the pre-invasive and invasive stages of cervical cancer. A gene expression profile (GSE7803) containing 21 invasive squamous cell cervical carcinoma samples, 10 normal squamous cervical epithelium samples and seven high-grade squamous intraepithelial cervical lesion samples, was obtained from the Gene Expression Omnibus. Differentially expressed genes (DEGs) were identified using significance analysis of microarray software, and a Gene Ontology (GO) enrichment analysis was conducted using the Database for Annotation, Visualization and Integrated Discovery. The miRNAs that interacted with the identified DEGs were selected, based on the TarBase v5.0 database. Regulatory networks were constructed from these selected miRNAs along with their corresponding target genes among the DEGs. The regulatory networks were visualized using Cytoscape. A total of 1,160 and 756 DEGs were identified in the pre-invasive and invasive stages of cervical cancer, respectively. The results of the GO enrichment demonstrated that the DEGs were predominantly involved in the immune response and the cell cycle, in the pre-invasive and invasive stages, respectively. Furthermore, a total of 18 and 26 characteristic miRNAs were screened in the pre-invasive and invasive stages, respectively. These miRNAs may be potential biomarkers and targets for the diagnosis and treatment of the different stages of cervical cancer.

OncomiR miR-96 and miR-182 promote cell proliferation and invasion through targeting ephrinA5 in hepatocellular carcinoma

EphrinA5, a member of the ephrinA subclass, is downregulated in hepatocellular carcinoma (HCC) and acts as a tumor suppressor. However, the upstream regulation mechanism of ephrinA5 remains unclear. In this study, we tried to identify and characterize the roles of miR-96 and miR-182 in the regulation of ephrinA5 expression in HCC. The expression levels of miR-96 and miR-182 were examined in 47 paired HCC and para-tumoral liver tissues using quantitative real-time RT-PCR. The luciferase reporter assay and western blotting were employed to dissect the association between miR-96/182 and ephrinA5 expression. Moreover, cells were treated with synthetic miR-96/182 precursors and inhibitors to assess their effects on HCC cell growth and migration. It was found that both miR-96 and miR-182 were upregulated in HCC compared to para-tumoral normal tissues. The expression of miR-96 and miR-182 was inversely associated with ephrinA5 protein levels. Furthermore, both miR-96 and miR-182 directly targeted the 3'UTR of the ephrinA5 mRNA and suppressed protein translation. The suppression of miR-96 and miR-182 led to reduced HCC cell proliferation and migration by negatively regulating ephrinA5 expression. In conclusion, miR-96 and miR-182 may act as oncomiRs in HCC by suppressing the expression of ephrinA5 and may play important roles in hepatocarcinogenesis. © 2015 Wiley Periodicals, Inc.

Dysregulation of the epigenome in human breast cancer: contributions of gene-specific DNA hypermethylation to breast cancer pathobiology and targeting the breast cancer methylome for improved therapy

Triple-negative breast cancers (including basal-like and claudin-low molecular subtypes) represent 20% to 25% of all breast cancers, but disproportionately contribute to breast cancer-associated death. We have identified a novel fundamental biological property of triple-negative breast cancers: most triple-negative breast cancers express aberrant DNA hypermethylation due to overexpression of DNA methyltransferase 3b (and hyperactivity of the DNA methyltransferase enzymes). DNA methyltransferase 3b overexpression occurs secondary to loss of miRNA-mediated post-transcriptional regulation. The resulting hyperactivity of DNA methyltransferase 3b produces concurrent DNA methylation-dependent silencing of numerous critical gene targets (including tumor suppressors and pro-apoptotic genes) and resistance to cytotoxic chemotherapy. This observation presents new opportunities for development of innovative treatment strategies on the basis of the epigenome as a novel therapeutic target in triple-negative breast cancers. Epigenetic therapy represents a new principle in cancer treatment in which restoration of critical molecular pathways occurs secondary to reexpression of silenced genes that encode negative mediators of cancer cell growth.

A genetic variant of miR-148a binding site in the SCRN1 3'-UTR is associated with susceptibility and prognosis of gastric cancer

Single nucleotide polymorphisms (SNPs) in the 3′-untranslated regions targeted by putative mircoRNA can change its binding strength, affecting the susceptibility and prognosis of cancer. We aimed to investigate the associations between SNPs within miR-148a binding sites and gastric cancer (GC) risk and prognosis. Using bioinformatics tools, we selected two SNPs (SCRN1 rs6976789 and PDYN rs2235749) located in miR-148a target sites. We genotyped the two SNPs in a case-control study comprising 753 GC patients and 949 cancer-free subjects. We found a significantly increased risk of GC associated with the SCRN1 rs6976789 C>T polymorphism [adjusted OR = 1.25, 95% confidence interval (CI) = 1.02–1.53; CT/TT vs. CC]. However, no significant association was found between the PDYN rs2235749 and GC risk in all genetic models. Furthermore, we evaluated whether SCRN1 rs6976789 affected the survival of GC patients. Results showed that individuals with SCRN1 rs6976789 TT genotype had poorer overall survival compared with those carried CC/CT genotypes in intestinal-type GC (adjusted HR = 2.47, 95% CI = 1.21–5.05). Luciferase report assay showed that the rs6976789 variant T allele influenced the binding ability of miR-148a. Our results suggested that the SCRN1 rs6976789 polymorphism may play an important role in the GC development and progression.

MicroRNA 520d-3p inhibits gastric cancer cell proliferation, migration, and invasion by downregulating EphA2 expression

Aberrant expression of microRNAs (miRNAs) has been shown to play important roles in cancer progression as a result of changes in expression of their target genes. In this study, we investigated the roles of miR-520d-3p on gastric cancer (GC) cell proliferation, migration, and invasion, and confirmed that this miRNA regulates EphA2 expression. The mRNA expression levels of miR-520d-3p and EphA2 in GC tissues and cell lines were evaluated. The clinical and prognostic significance of miR-520d-3p was assessed. The biological function of miR-520d-3p in GC cells was investigated using a methylthiazolyldiphenyl-tetrazolium bromide assay, cell cycle assay, transwell invasion assay, and wound-healing assay. miR-520d-3p expression was down-regulated and inversely correlated with the expression of EphA2 in GC tissues and cell lines. Lower expression of miR-520d-3p was associated with tumor invasion (P = 0.0357), lymph nodes metastasis (P = 0.0272), a higher clinical stage (P = 0.0041), and poorer overall survival (P = 0.0105). Luciferase assays revealed that miR-520d-3p inhibited EphA2 expression by targeting the 3'-untranslated region of EphA2 mRNA. Overexpression of miR-520d-3p dramatically inhibited the proliferation, cell cycle progression, invasion, and migration of GC cells, while down-regulation substantially promoted these properties. Moreover, c-Myc, CyclinD1, and matrix metalloproteinase-9 expression levels were down-regulated in miR-520d-3p mimic-transfected cells and up-regulated in miR-520d-3p inhibitor-transfected cells. Taken together, our data showed that miR-520d-3p appears to contribute to GC progression via the regulation of EphA2 and could serve as a novel prognostic and potential therapeutic marker.

GPER mediated estradiol reduces miR-148a to promote HLA-G expression in breast cancer

Breast cancer is the most common malignant diseases in women. miR-148a plays an important role in regulation of cancer cell proliferation and cancer invasion and down-regulation of miR-148a has been reported in both estrogen receptor (ER) positive and triple-negative (TN) breast cancer. However, the regulation mechanism of miR-148a is unclear. The role of estrogen signaling, a signaling pathway is important in development and progression of breast cancer. Therefore, we speculated that E2 may regulate miR-148a through G-protein-coupled estrogen receptor-1 (GPER). To test our hypothesis, we checked the effects of E2 on miR-148a expression in ER positive breast cancer cell MCF-7 and TN cancer cell MDA-MB-231. Then we used GPER inhibitor G15 to investigate whether GPER is involved in regulation of E2 on miR-148a. Furthermore, we analyzed whether E2 affects the expression of HLA-G, which is a miR-148a target gene through GPER. The results showed that E2 induces the level of miR-148a in MCF-7 and MDA-MB-231 cells, GPER mediates the E2-induced increase in miR-148a expression in MCF-7 and MDA-MB-231 cells and E2-GPER regulates the expression of HLA-G by miR-148a. In conclusion, our findings offer important new insights into the ability of estrogenic GPER signaling to trigger HLA-G expression through inhibiting miR-148a that supports immune evasion in breast cancer.

miR-206 inhibits cell migration through direct targeting of the actin-binding protein coronin 1C in triple-negative breast cancer

Patients with triple-negative breast cancer (TNBC) have an overall poor prognosis, which is primarily due to a high metastatic capacity of these tumors. Novel therapeutic approaches to target the signaling pathways that promote metastasis are desirable, in order to improve the outcome for these patients. A loss of function of a microRNA, miR-206, is related to increased metastasis potential in breast cancers but the mechanism is not known. In this study, we show that miR-206 was decreased in TNBC clinical tumor samples and cell lines whereas one of its predicted targets, actin-binding protein CORO1C, was increased. Expression of miR-206 significantly reduced proliferation and migration while repressing CORO1C mRNA and protein levels. We demonstrate that miR-206 interacts with the 3'-untranslated region (3'-UTR) of CORO1C and regulates this gene post-transcriptionally. This post-transcriptional regulation was dependent on two miR-206-binding sites within the 3'-UTR of CORO1C and was relieved by mutations of corresponding sites. Further, silencing of CORO1C reduced tumor cell migration and affected the actin skeleton and cell morphology, similar to miR-206 expression, but did not reduce proliferation. In accordance with this, overexpression of CORO1C rescued the inhibitory effect of miR-206 on cell migration. Our findings suggest that miR-206 represses tumor cell migration through direct targeting of CORO1C in TNBC cells which modulates the actin filaments. This pathway is a novel mechanism that offers a mechanistic basis through which the metastatic potential of TNBC tumors could be targeted.

Fatty acid and phospholipid biosynthetic pathways are regulated throughout mammary epithelial cell differentiation and correlate to breast cancer survival

This work combined gene and protein expression, gas chromatography-flame ionization detector, and hydrophilic interaction liquid chromatography-tandem mass spectrometry to compare lipid metabolism changes in undifferentiated/proliferating vs. functionally differentiated mammary epithelial cells (MECs) and to study their correlation to breast cancer survival. Sixty-eight genes involved in lipid metabolism were changed in MEC differentiation. Differentiated cells showed induction of Elovl6 (2-fold), Scd1 (4-fold), and Fads2 (2-fold), which correlated with increased levels of C16:1 n-7 and C18:1 n-9 (1.5-fold), C20:3 n-6 (2.5-fold), and C20:4 n-6 (6-fold) fatty acids (FAs) and more phospholipids (PLs) containing these species. Further, increased expression (2- to 3-fold) of genes in phosphatidylethanolamine (PE) de novo biosynthesis resulted in a 20% PE increase. Proliferating/undifferentiated cells showed higher C16:0 (1.7-fold) and C18:2 n-6 (4.2-fold) levels and more PLs containing C16:0 FAs [PC(16:0/16:1), PG(16:0/18:2), PG(16:0/18:1), and SM(16:0/18:0)]. Kaplan-Meier analysis of data from 3455 patients with breast cancer disclosed a positive correlation for 59% of genes expressed in differentiated MECs with better survival. PE biosynthesis and FA oxidation correlated with better prognosis in patients with breast cancer, including the basal-like subtype. Therefore, genes involved in mammary gland FA and PL metabolism and their resulting molecular species reflect the cellular proliferative ability and differentiation state and deserve further studies as potential markers of breast cancer progression

MiR-200, a new star miRNA in human cancer

MicroRNAs (miRNAs) are a set of non-coding small RNA molecules in control of gene expression at posttranscriptional/translational level. They not only play crucial roles in normal developmental progress, but also are commonly dysregulated in human diseases, including cancer. MiR-200 is a family of tumor suppressor miRNAs consisting of five members, which are significantly involved in inhibition of epithelial-to-mesenchymal transition (EMT), repression of cancer stem cells (CSCs) self-renewal and differentiation, modulation of cell division and apoptosis, and reversal of chemoresistance. In this article, we summarize the latest findings with regard to the tumor suppressor signatures of miR-200 and the regulatory mechanisms of miR-200 expression. The collected evidence supports that miR-200 is becoming a new star miRNA in study of human cancer.

MicroRNAs and triple negative breast cancer

Triple Negative Breast Cancer (TNBC) is a very aggressive tumor subtype, which still lacks specific markers for an effective targeted therapy. Despite the common feature of negativity for the three most relevant receptors (ER, PgR and HER2), TNBC is a very heterogeneous disease where different subgroups can be recognized, and both gene and microRNA profiling studies have recently been carried out to dissect the different molecular entities. Moreover, several microRNAs playing a crucial role in triple negative breast cancer biology have been identified, providing the experimental basis for a possible therapeutic application. Indeed, the causal involvement of microRNAs in breast cancer and the possible use of these small noncoding RNA molecules as biomarkers has been extensively studied with promising results. Their application as therapeutic tools might represent an innovative approach, especially for a tumor subgroup still lacking an efficient and specific therapy such as TNBC. In this review, we summarize our knowledge on the most important microRNAs described in TNBC.

Regulation of the microRNA 200b (miRNA-200b) by transcriptional regulators PEA3 and ELK-1 protein affects expression of Pin1 protein to control anoikis

MicroRNA (miRNA) 200s regulate E-cadherin by directly targeting ZEB1/ZEB2, which are transcriptional repressors of E-cadherin. Decreased expression of E-cadherin results in cancer cells losing interaction with the extracellular matrix and detaching from the primary tumor. Normally, cells will undergo anoikis after losing interaction with the extracellular matrix. Cancer cells must, therefore, possess the ability to resist anoikis during the process of metastasis. Here we show that miRNA-200b regulates anoikis by directly targeting the 3' UTR of Pin1 mRNA and regulating Pin1 expression at the translational level. We found that down-regulation of miRNA-200b promotes cancer cells survival during metastasis, and the homeless state of these cells resulted in decreased expression of miRNA-200b in the MCF-7 cell line. We also found that expression of miRNA-200b is down-regulated in human breast cancer during lymph node metastasis, which has a significant negative correlation with Pin1 expression. Two members of the ETS (E-26) family (PEA3 and ELK-1) regulate the expression of miRNA-200b. PEA3 promotes the expression of miRNA-200b, and ELK-1 is a transcriptional repressor of miRNA-200b. In addition, miRNA-200b regulates the activity of PEA3 and ELK-1 via the Pin1-pERK pathway and forms self-regulated feedback loops. This study characterizes the role of miRNA-200b in the regulation of anoikis and demonstrates the regulation of its own expression in the process of metastasis.

DNMT1 is regulated by ATP-citrate lyase and maintains methylation patterns during adipocyte differentiation

During adipocyte differentiation, significant epigenomic changes occur in association with the implementation of the adipogenic program. We have previously shown that histone acetylation increases during differentiation in a manner dependent on acetyl coenzyme A (acetyl-CoA) production by the enzyme ATP-citrate lyase (ACL). Whether ACL regulates nuclear targets in addition to histones during differentiation is not clear. In this study, we report that DNA methyltransferase 1 (DNMT1) levels in adipocytes are controlled in part by ACL and that silencing of DNMT1 can accelerate adipocyte differentiation. DNMT1 gene expression is induced early in 3T3-L1 adipocyte differentiation during mitotic clonal expansion and is critical for maintenance of DNA and histone H3K9 methylation patterns during this period. In the absence of DNMT1, adipocyte-specific gene expression and lipid accumulation occur precociously. Later in differentiation, DNMT1 levels decline in an ACL-dependent manner. ACL-mediated suppression of DNMT1 occurs at least in part by promoting expression of microRNA 148a (miR-148a), which represses DNMT1. Ectopic expression of miR-148a accelerates differentiation under standard conditions and can partially rescue a hypermethylation-mediated differentiation block. The data suggest a role for DNMT1 in modulating the timing of differentiation and describe a novel ACL-miR-148a-dependent mechanism for regulating DNMT1 during adipogenesis.

MiR203 mediates subversion of stem cell properties during mammary epithelial differentiation via repression of ΔNP63α and promotes mesenchymal-to-epithelial transition

During reproductive life, the mammary epithelium undergoes consecutive cycles of proliferation, differentiation and apoptosis. Doing so relies on the retained proliferative capacity, prolonged lifespan and developmental potency of mammary stem cells (MaSCs). ΔNp63α, the predominant TP63 isoform in mammary epithelia, is robustly expressed in MaSCs and is required for preservation of self-renewing capacity in diverse epithelial structures. However, the mechanism(s) underlying subversion of this activity during forfeiture of self-renewing capacity are poorly understood. MicroRNAs (miRNAs) govern critical cellular functions including stem cell maintenance, development, cell cycle regulation and differentiation by disrupting translation of target mRNAs. Data presented here indicate that expression of miR203, a miRNA that targets ΔNp63α and ΔNp63β is activated during luminal epithelial differentiation and that this pattern is observed in the murine mammary hierarchy. In addition, we present evidence that the transcription factor Zeb1 represses miR203 expression, thus enhancing ΔNp63α protein levels. Furthermore, ectopic miR203 suppresses ΔNp63α expression, proliferation and colony formation. The anti-clonogenic effects mediated by miR203 require suppression of ΔNp63α. In addition, ectopic miR203 promotes mesenchymal-to-epithelial transition and disrupts activities associated with epithelial stem cells. These studies support a model in which induction of miR203 mediates forfeiture of self-renewing capacity via suppression of ΔNp63α and may also have anti-tumorigenic activity through its reduction of EMT and cancer stem cell populations.