Validation of expression patterns for nine miRNAs in 204 lymph-node negative breast cancers

The Role of miR-375-3p, miR-210-3p and Let-7e-5p in the Pathological Response of Breast Cancer Patients to Neoadjuvant Therapy

Background and Objectives: Prediction of response to therapy remains a continuing challenge in treating breast cancer, especially for identifying molecular tissue markers that best characterize resistant tumours. Microribonucleic acids (miRNA), known as master modulators of tumour phenotype, could be helpful candidates for predicting drug resistance. We aimed to assess the association of miR-375-3p, miR-210-3p and let-7e-5p in breast cancer tissues with pathological response to neoadjuvant therapy (NAT) and clinicopathological data. Material and methods: Sixty female patients diagnosed with invasive breast cancer at The Oncology Institute “Ion Chiricuță”, Cluj-Napoca, Romania (IOCN) were included in this study. Before patients received any treatment, fresh breast tissue biopsies were collected through core biopsy under echographic guidance and processed for total RNA extraction and miRNA quantification. The Cancer Genome Atlas Breast Invasive Carcinoma (TCGA-BRCA) database was used as an independent external validation cohort. Results: miR-375-3p expression was associated with more differentiated tumours, hormone receptor presence and lymphatic invasion. According to the Miller–Payne system, a higher miR-375-3p expression was calculated for patients that presented with intermediate versus (vs.) no pathological response. Higher miR-210-3p expression was associated with an improved response to NAT in both Miller–Payne and RCB evaluation systems. Several druggable mRNA targets were correlated with miR-375-3p and miR-210-3p expression, with upstream analysis using the IPA knowledge base revealing a list of possible chemical and biological targeting drugs. Regarding let-7e-5p, no significant association was noticed with any of the analysed clinicopathological data. Conclusions: Our results suggest that tumours with higher levels of miR-375-3p are more sensitive to neoadjuvant therapy compared to resistant tumours and that higher miR-210-3p expression in responsive tumours could indicate an excellent pathological response.

CELF Family Proteins in Cancer: Highlights on the RNA-Binding Protein/Noncoding RNA Regulatory Axis

Post-transcriptional modifications to coding and non-coding RNAs are unquestionably a pivotal way in which human mRNA and protein diversity can influence the different phases of a transcript's life cycle. CELF (CUGBP Elav-like family) proteins are RBPs (RNA-binding proteins) with pleiotropic capabilities in RNA processing. Their responsibilities extend from alternative splicing and transcript editing in the nucleus to mRNA stability, and translation into the cytoplasm. In this way, CELF family members have been connected to global alterations in cancer proliferation and invasion, leading to their identification as potential tumor suppressors or even oncogenes. Notably, genetic variants, alternative splicing, phosphorylation, acetylation, subcellular distribution, competition with other RBPs, and ultimately lncRNAs, miRNAs, and circRNAs all impact CELF regulation. Discoveries have emerged about the control of CELF functions, particularly via noncoding RNAs, and CELF proteins have been identified as competing, antagonizing, and regulating agents of noncoding RNA biogenesis. On the other hand, CELFs are an intriguing example through which to broaden our understanding of the RBP/noncoding RNA regulatory axis. Balancing these complex pathways in cancer is undeniably pivotal and deserves further research. This review outlines some mechanisms of CELF protein regulation and their functional consequences in cancer physiology.

Nutraceuticals in the Mediterranean Diet: Potential Avenues for Breast Cancer Treatment

The traditional Mediterranean Diet constitutes a food model that refers to the dietary patterns of the population living in countries bordering the Mediterranean Sea in the early 1960s. A huge volume of literature data suggests that the Mediterranean-style diet provides several dietary compounds that have been reported to exert beneficial biological effects against a wide spectrum of chronic illnesses, such as cardiovascular and neurodegenerative diseases and cancer including breast carcinoma. Among bioactive nutrients identified as protective factors for breast cancer, natural polyphenols, retinoids, and polyunsaturated fatty acids (PUFAs) have been reported to possess antioxidant, anti-inflammatory, immunomodulatory and antitumoral properties. The multiple anticancer mechanisms involved include the modulation of molecular events and signaling pathways associated with cell survival, proliferation, differentiation, migration, angiogenesis, antioxidant enzymes and immune responses. This review summarizes the anticancer action of some polyphenols, like resveratrol and epigallocatechin 3-gallate, retinoids and omega-3 PUFAs by highlighting the important hallmarks of cancer in terms of (i) cell cycle growth arrest, (ii) apoptosis, (iii) inflammation and (iv) angiogenesis. The data collected from in vitro and in vivo studies strongly indicate that these natural compounds could be the prospective candidates for the future anticancer therapeutics in breast cancer disease.

MicroRNA profiling in serum: Potential signatures for breast cancer diagnosis

BACKGROUND

Circulating microRNAs (miRNAs) prove to be potential non-invasive indicators of cancers. The purpose of this study is to profile serum miRNA expression in breast cancer (BC) patients to find potential biomarkers for BC diagnosis.

METHODS

The miRNA expression patterns of serum samples from 216 BC patients and 214 normal control subjects were compared. A four-phase validation was conducted for biomarker identification. In the screening phase, the Exiqon miRNA qPCR panel was employed to select candidates, which were further analyzed by quantitative reverse transcriptase PCR in the following training, testing, and external validation phases.

RESULTS

A 12-miRNA (let-7b-5p, miR-106a-5p, miR-19a-3p, miR-19b-3p, miR-20a-5p, miR-223-3p, miR-25-3p, miR-425-5p, miR-451a, miR-92a-3p, miR-93-5p, and miR-16-5p) panel in serum was constructed. The diagnostic performance of the panel was assessed using ROC curve analyses. The area under the curves (AUCs) were 0.952, 0.956, 0.941 and 0.950 for the four separate phases, respectively. Additionally, the expression features of the 12 miRNAs were further explored in 32 pairs of BC tumor and para-tumor tissues, and 32 pairs of serum exosomes samples from patients and healthy subjects. miR-16-5p, miR-106a-5p, miR-25-3p, miR-425-5p, and miR-93-5p were highly overexpressed and let-7b-5p was conversely downregulated in tumor tissues. Excluding miR-20a-5p and miR-223-3p, the 10 other miRNAs were all significantly upregulated in BC serum-derived exosomes.

CONCLUSION

A signature consisting of 12 serum miRNAs was identified and showed potential for use in non-invasive diagnosis of BC.

Hsa-miR-375/RASD1 Signaling May Predict Local Control in Early Breast Cancer

Background: In order to characterize the various subtypes of breast cancer more precisely and improve patients selection for breast conserving therapy (BCT), molecular profiling has gained importance over the past two decades. MicroRNAs, which are small non-coding RNAs, can potentially regulate numerous downstream target molecules and thereby interfere in carcinogenesis and treatment response via multiple pathways. The aim of the current two-phase study was to investigate whether hsa-miR-375-signaling through RASD1 could predict local control (LC) in early breast cancer. Results: The patient and treatment characteristics of 81 individuals were similarly distributed between relapse (n = 27) and control groups (n = 54). In the pilot phase, the primary tumors of 28 patients were analyzed with microarray technology. Of the more than 70,000 genes on the chip, 104 potential hsa-miR-375 target molecules were found to have a lower expression level in relapse patients compared to controls (p-value < 0.2). For RASD1, a hsa-miR-375 binding site was predicted by an in silico search in five mRNA-miRNA databases and mechanistically proven in previous pre-clinical studies. Its expression levels were markedly lower in relapse patients than in controls (p-value of 0.058). In a second phase, this finding could be validated in an independent set of 53 patients using ddPCR. Patients with enhanced levels of hsa-miR-375 compared to RASD1 had a higher probability of local relapse than those with the inverse expression pattern of the two markers (log-rank test, p-value = 0.069). Conclusion: This two-phase study demonstrates that hsa-miR-375/RASD1 signaling is able to predict local control in early breast cancer patients, which—to our knowledge—is the first clinical report on a miR combined with one of its downstream target proteins predicting LC in breast cancer.

Modulatory Role of microRNAs in Triple Negative Breast Cancer with Basal-Like Phenotype

Development of new research, classification, and therapeutic options are urgently required due to the fact that TNBC is a heterogeneous malignancy. The expression of high molecular weight cytokeratins identifies a biologically and clinically distinct subgroup of TNBCs with a basal-like phenotype, representing about 75% of TNBCs, while the remaining 25% includes all other intrinsic subtypes. The triple negative phenotype in basal-like breast cancer (BLBC) makes it unresponsive to endocrine therapy, i.e., tamoxifen, aromatase inhibitors, and/or anti-HER2-targeted therapies; for this reason, only chemotherapy can be considered an approach available for systemic treatment even if it shows poor prognosis. Therefore, treatment for these subgroups of patients is a strong challenge for oncologists due to disease heterogeneity and the absence of unambiguous molecular targets. Dysregulation of the cellular miRNAome has been related to huge cellular process deregulations underlying human malignancy. Consequently, epigenetics is a field of great promise in cancer research. Increasing evidence suggests that specific miRNA clusters/signatures might be of clinical utility in TNBCs with basal-like phenotype. The epigenetic mechanisms behind tumorigenesis enable progress in the treatment, diagnosis, and prevention of cancer. This review intends to summarize the epigenetic findings related to miRNAome in TNBCs with basal-like phenotype.

Sparse semiparametric canonical correlation analysis for data of mixed types

Canonical correlation analysis investigates linear relationships between two sets of variables, but often works poorly on modern datasets due to high-dimensionality and mixed data types (continuous/binary/zero-inflated). We propose a new approach for sparse canonical correlation analysis of mixed data types that does not require explicit parametric assumptions. Our main contribution is the use of truncated latent Gaussian copula to model the data with excess zeroes, which allows us to derive a rank-based estimator of latent correlation matrix without the estimation of marginal transformation functions. The resulting semiparametric sparse canonical correlation analysis method works well in high-dimensional settings as demonstrated via numerical studies, and application to the analysis of association between gene expression and micro RNA data of breast cancer patients.

The emerging role of miRNA clusters in breast cancer progression

Micro RNAs (miRNAs) are small non-coding RNAs that are essential for regulation of gene expression of the target genes. Large number of miRNAs are organized into defined units known as miRNA clusters (MCs). The MCs consist of two or more than two miRNA encoding genes driven by a single promoter, transcribed together in the same orientation, that are not separated from each other by a transcription unit. Aberrant miRNA clusters expression is reported in breast cancer (BC), exhibiting both pro-tumorogenic and anti-tumorigenic role. Altered MCs expression facilitates to breast carcinogenesis by promoting the breast cells to acquire the various hallmarks of the cancer. Since miRNA clusters contain multiple miRNA encoding genes, targeting cluster may be more attractive than targeting individual miRNAs. Besides targeting dysregulated miRNA clusters in BC, studies have focused on the mechanism of action, and its contribution to the progression of the BC. The present review provides a comprehensive overview of dysregulated miRNA clusters and its role in the acquisition of cancer hallmarks in BC. More specifically, we have presented the regulation, differential expression, classification, targets, mechanism of action, and signaling pathways of miRNA clusters in BC. Additionally, we have also discussed the potential utility of the miRNA cluster as a diagnostic and prognostic indicator in BC.

Good or not good: Role of miR-18a in cancer biology

miR-18a is a member of primary transcript called miR-17-92a (C13orf25 or MIR17HG) which also contains five other miRNAs: miR-17, miR-19a, miR-20a, miR-19b and miR-92a. This cluster as a whole shows specific characteristics, where miR-18a seems to be unique. In contrast to the other members, the expression of miR-18a is additionally controlled and probably functions as its own internal controller of the cluster. miR-18a regulates many genes involved in proliferation, cell cycle, apoptosis, response to different kinds of stress, autophagy and differentiation. The disturbances of miR-18a expression are observed in cancer as well as in different diseases or pathological states. The miR-17-92a cluster is commonly described as oncogenic and it is known as 'oncomiR-1', but this statement is a simplification because miR-18a can act both as an oncogene and a suppressor. In this review we summarize the current knowledge about miR-18a focusing on its regulation, role in cancer biology and utility as a potential biomarker.

MiR-18a and miR-18b are expressed in the stroma of oestrogen receptor alpha negative breast cancers

BACKGROUND

Previously, we have shown that miR-18a and miR-18b gene expression strongly correlates with high proliferation, oestrogen receptor -negativity (ER^-), cytokeratin 5/6 positivity and basal-like features of breast cancer.

METHODS

We investigated the expression and localization of miR-18a and -18b in formalin fixed paraffin embedded (FFPE) tissue from lymph node negative breast cancers (n = 40), by chromogenic in situ hybridization (CISH). The expression level and in situ localization of miR-18a and -18b was assessed with respect to the presence of tumour infiltrating lymphocytes (TILs) and immunohistochemical markers for ER, CD4, CD8, CD20, CD68, CD138, PAX5 and actin. Furthermore, in two independent breast cancer cohorts (94 and 377 patients) the correlation between miR-18a and -18b expression and the relative quantification of 22 immune cell types obtained from the CIBERSORT tool was assessed.

RESULTS

CISH demonstrated distinct and specific cytoplasmic staining for both miR-18a and miR-18b, particularly in the intratumoural stroma and the stroma surrounding the tumour margin. Staining by immunohistochemistry revealed some degree of overlap of miR-18a and -18b with CD68 (monocytes/macrophages), CD138 (plasma cells) and the presence of high percentages of TILs. CIBERSORT analysis showed a strong correlation between M1-macrophages and CD4+ memory activated T-cells with mir-18a and -18b.

CONCLUSIONS

Our study demonstrates that miR-18a and miR-18b expression is associated with ER- breast tumours that display a high degree of inflammation. This expression is potentially associated specifically with macrophages. These results suggest that miR-18a and miR-18b may play a role in the systemic immunological response in ER^- tumours.

Epigallocatechin gallate (EGCG) suppresses growth and tumorigenicity in breast cancer cells by downregulation of miR-25

The aim of the present study was to investigate the anticancer effects and potential mechanisms of polyphenol epigallocatechin-3-gallate (EGCG) on breast cancer MCF-7 cells in vitro and in vivo. Our results showed that EGCG significantly inhibited MCF-7 cell viability in a time- and dose-dependent manner. Flow cytometry analysis indicated that EGCG induced apoptosis and disrupted cell cycle progression at G2/M phase. Moreover, EGCG inhibited miR-25 expression and increased PARP, pro-caspase-3 and pro-caspase-9 at protein levels. Restoration of miR-25 inhibited EGCG-induced cell apoptosis. Furthermore, EGCG suppressed tumor growth in vivo by downregulating the expression of miR-25 and proteins associated with apoptosis, which was further confirmed by a reduction of Ki-67 and increase of pro-apoptotic PARP expression as determined by immunohistochemistry staining. These findings indicate that EGCG possesses chemopreventive potential in breast cancer which may serve as a promising anticancer agent for clinical applications.

Apoptotic tumor cell-derived microRNA-375 uses CD36 to alter the tumor-associated macrophage phenotype

Tumor-immune cell interactions shape the immune cell phenotype, with microRNAs (miRs) being crucial components of this crosstalk. How they are transferred and how they affect their target landscape, especially in tumor-associated macrophages (TAMs), is largely unknown. Here we report that breast cancer cells have a high constitutive expression of miR-375, which is released as a non-exosome entity during apoptosis. Deep sequencing of the miRome pointed to enhanced accumulation of miR-375 in TAMs, facilitated by the uptake of tumor-derived miR-375 via CD36. In macrophages, miR-375 directly targets TNS3 and PXN to enhance macrophage migration and infiltration into tumor spheroids and in tumors of a xenograft mouse model. In tumor cells, miR-375 regulates CCL2 expression to increase recruitment of macrophages. Our study provides evidence for miR transfer from tumor cells to TAMs and identifies miR-375 as a crucial regulator of phagocyte infiltration and the subsequent development of a tumor-promoting microenvironment.

The mode of miRNA transfer between tumour-immune cells is usually via exosomes. Here, the authors show that an alternative mode of transfer whereby miR-375 from apoptotic tumour cells can be transferred to tumour-associated macrophages via CD36 receptor, which induces macrophage migration and infiltration to the tumours.

A SRSF1 self-binding mechanism restrains Mir505-3p from inhibiting proliferation of neural tumor cell lines

Srsf1 has currently been demonstrated to be an oncogene that is precisely autoregulated for normal physiology. Although Mir505-3p has been reported as one of the regulatory miRNAs of Srsf1 in mouse embryonic fibroblast (MEF), the inhibitory effect of Mir505-3p on Srsf1 is poorly described in neural tumors. Whether SRSF1 autoregulation interferes with miRNA targeting on the Srsf1 transcript is unclear. In this work, we screened out one target site, out of three potential target sites on 3' UTR of Srsf1 transcript, that was required for Mir505-3p targeting. We showed that Mir505-3p was capable of inhibiting tumor proliferation driven by SRSF1 in two neural tumor cell lines, Neuro-2a (N2a) and U251, exclusively in serum-reduced condition. We observed that the protein level of SRSF1 was gradually promoted by increasing concentration of serum. We also found that overexpressed exogenous SRSF1 protein abolished this RNA interfering related targeting, suggesting that serum-rich condition restrains Mir505-3p from inhibiting Srsf1 transcript after inducing SRSF1 protein overexpression. Moreover, by applying bioinformatic analysis, the SRSF1 self-binding motif was found proximal to the Mir505-3p target site, which was required for a SRSF1 competitive self-binding interaction. The interaction of overexpressed exogenous SRSF1 protein and the SRSF1 self-binding motif was sufficient to restrain Mir505-3p from targeting the Srsf1 transcript. These results provide a better understanding of how tumorous microenvironment influences anticancer therapy in the neural system, suggesting potential strategic design for anticancer drugs.

A myriad of roles of miR-25 in health and disease

Small non-coding RNAs including microRNAs (miRNAs) have been recently recognized as important regulators of gene expression. MicroRNAs play myriads of roles in physiological processes as well as in the pathogenesis of a number of diseases by translational repression or mRNA destabilization of numerous target genes. The miR-106b-25 cluster is highly conserved in vertebrates and consists of three members including miR-106b, miR-93 and miR-25. MiR-106b and miR-93 share the same seed sequences; however, miR-25 has only a similar seed sequence resulting in different predicted target mRNAs. In this review, we specifically focus on the role of miR-25 in healthy and diseased conditions. Many of miR-25 target mRNAs are involved in biological processes such as cell proliferation, differentiation, and migration, apoptosis, oxidative stress, inflammation, calcium handling, etc. Therefore, it is no surprise that miR-25 has been reported as a key regulator of common cancerous and non-cancerous diseases. MiR-25 plays an important role in the pathogenesis of acute myocardial infarction, left ventricular hypertrophy, heart failure, diabetes mellitus, diabetic nephropathy, tubulointerstitial nephropathy, asthma bronchiale, cerebral ischemia/reperfusion injury, neurodegenerative diseases, schizophrenia, multiple sclerosis, etc. MiR-25 is also a well-described oncogenic miRNA playing a crucial role in the development of many tumor types including brain tumors, lung, breast, ovarian, prostate, thyroid, oesophageal, gastric, colorectal, hepatocellular cancers, etc. In this review, our aim is to discuss the translational therapeutic role of miR-25 in common diseased conditions based on relevant basic research and clinical studies.

Correlation between polymorphisms in microRNA-regulated genes and cervical cancer susceptibility in a Xinjiang Uygur population

We explored the correlation between single nucleotide polymorphisms (SNPs) and susceptibility to cervical cancer (CC) in a Xinjiang Uygur population. Ten SNPs in eight miRNA-regulated genes were selected for analysis. Odds ratios (ORs) and 95% confidence intervals (95% CIs) were calculated using unconditional logistic regression analysis. Multivariate logistic regression analysis was used to detect correlations between SNPs and CC. We found that minor allele "C" of rs512715 in NEAT1 was associated with an increased risk of CC in the allele, codominant, dominant, overdominant and log-additive models. Minor allele "C" of rs4777498 in CELF6 was associated with an increased risk of CC in the recessive model. Minor allele "C" of rs3094 in RNASE4 was associated with increased risk of CC in the allele, dominant and log-additive models. In clinical stage III/IV CC patients, minor allele "C" of rs3094 in RNASE4 and minor allele "C" of rs8004334 in JDP2 were associated with increased risk. In subtype squamous carcinoma CC patients, minor allele "C" of rs512715 in NEAT1 and minor allele "C" of rs3094 in RNASE4 were associated with increased risk. In subtype adenocarcinoma CC patients, minor allele "C" of rs3094 in RNASE was associated with increased risk.

MicroRNA-Mediated Regulation of HMGB1 in Human Hepatocellular Carcinoma

High-mobility group box 1 (HMGB1) is a potential therapeutic target and novel biomarker in a variety of malignant tumors, including hepatocellular carcinoma (HCC). More recently, a number of microRNAs (miRNAs) are identified as a class of regulators for broad control of HMGB1-mediated biological actions in eukaryotic cells. In this review article we will describe representative miRNAs involved in regulating the HMGB1 signaling pathways in HCC cell lines and/or animal models. We also propose the possible mechanisms underlying the miRNA/HMGB1 axis and discuss the future clinical significance of miRNAs targeting HMGB1 molecule for HCC therapy.

MicroRNA-target cross-talks: Key players in glioblastoma multiforme

The role of microRNAs in brain cancer is still naive. Some act as oncogene and others as tumor suppressors. Discovery of efficient biomarkers is mandatory to debate that aggressive disease. Bioinformatically selected microRNAs and their targets were investigated to evaluate their putative signature as diagnostic and prognostic biomarkers in primary glioblastoma multiforme. Expression of a panel of seven microRNAs (hsa-miR-34a, hsa-miR-16, hsa-miR-17, hsa-miR-21, hsa-miR-221, hsa-miR-326, and hsa-miR-375) and seven target genes ( E2F3, PI3KCA, TOM34, WNT5A, PDCD4, DFFA, and EGFR) in 43 glioblastoma multiforme specimens were profiled compared to non-cancer tissues via quantitative reverse transcription-polymerase chain reaction. Immunohistochemistry staining for three proteins (VEGFA, BAX, and BCL2) was performed. Gene enrichment analysis identified the biological regulatory functions of the gene panel in glioma pathway. MGMT ( O-6-methylguanine-DNA methyltransferase) promoter methylation was analyzed for molecular subtyping of tumor specimens. Our data demonstrated a significant upregulation of five microRNAs (hsa-miR-16, hsa-miR-17, hsa-miR-21, hsa-miR-221, and hsa-miR-375), three genes ( E2F3, PI3KCA, and Wnt5a), two proteins (VEGFA and BCL2), and downregulation of hsa-miR-34a and three other genes ( DFFA, PDCD4, and EGFR) in brain cancer tissues. Receiver operating characteristic analysis revealed that miR-34a (area under the curve = 0.927) and miR-17 (area under the curve = 0.900) had the highest diagnostic performance, followed by miR-221 (area under the curve = 0.845), miR-21 (area under the curve = 0.836), WNT5A (area under the curve = 0.809), PDCD4 (area under the curve = 0.809), and PI3KCA (area under the curve = 0.800). MGMT promoter methylation status was associated with high miR-221 levels. Moreover, patients with VEGFA overexpression and downregulation of TOM34 and BAX had poor overall survival. Nevertheless, miR-17, miR-221, and miR-326 downregulation were significantly associated with high recurrence rate. Multivariate analysis by hierarchical clustering classified patients into four distinct groups based on gene panel signature. In conclusion, the explored microRNA-target dysregulation could pave the road toward developing potential therapeutic strategies for glioblastoma multiforme. Future translational and functional studies are highly recommended to better understand the complex bio-molecular signature of this difficult-to-treat tumor.

Mir505-3p regulates axonal development via inhibiting the autophagy pathway by targeting Atg12

In addition to the canonical role in protein homeostasis, autophagy has recently been found to be involved in axonal dystrophy and neurodegeneration. Whether autophagy may also be involved in neural development remains largely unclear. Here we report that Mir505-3p is a crucial regulator for axonal elongation and branching in vitro and in vivo, through modulating autophagy in neurons. We identify that the key target gene of Mir505-3p in neurons is Atg12, encoding ATG12 (autophagy-related 12) which is an essential component of the autophagy machinery during the initiation and expansion steps of autophagosome formation. Importantly, axonal development is compromised in brains of mir505 knockout mice, in which autophagy signaling and formation of autophagosomes are consistently enhanced. These results define Mir505-3p-ATG12 as a vital signaling cascade for axonal development via the autophagy pathway, further suggesting the critical role of autophagy in neural development.

Bioinformatics analyses of the differences between lung adenocarcinoma and squamous cell carcinoma using The Cancer Genome Atlas expression data

The present study aimed to explore gene and microRNA (miRNA) expression differences between lung adenocarcinoma (LUAD) and lung squamous cell carcinoma (LUSC). Differentially expressed genes (DEGs) and differentially expressed miRNAs (DEMs) were identified by analyzing mRNA and miRNA expression data in normal and cancerous lung tissues that were obtained from The Cancer Genome Atlas database. A total of 778 DEGs and 7 DEMs were identified. Altered gene functions and signaling pathways were investigated using Gene Ontology and Kyoto Encyclopedia of Genes and Genomes analyses, which revealed that DEGs were significantly enriched in extracellular matrix organization, cell differentiation, negative regulation of toll signaling pathway, and several other terms and pathways. Transcription factor (TF)-miRNA-gene networks in LUAD and LUSC were predicted using the TargetScan, Miranda, and TRANSFAC databases, which revealed the regulatory links among the TFs, DEMs, and DEGs. The central TFs, i.e., the TFs in the middle of the TF-miRNA-gene network, of LUAD and LUSC were similar. Although LUAD and LUSC shared similar miRNAs in the predicted networks, miR-29b-3p was demonstrated to be upregulated only in LUAD, whereas miR-1, miR-105-5p, and miR-193b-5p were altered in LUSC. These findings may improve our understanding of the different molecular mechanisms in non-small cell lung cancers and may promote new and accurate strategies for prevention, diagnosis, and treatment.

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

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

MicroRNAs and Their Impact on Breast Cancer, the Tumor Microenvironment, and Disparities

Breast cancer is a worldwide health issue as it represents the leading cause of cancer in women and the second-leading cause of cancer-related mortality in women, with an increasing incidence. Nothing speaks more clearly to the shocking breast cancer health disparities than the fact that African American (AA) women are as likely to get breast cancer as Caucasian American (CA) women, yet have a higher breast cancer death rate. It is becoming increasingly apparent that racial disparity in cancer exists due to molecular differences in tumor biology as well as, or in addition to, socioeconomic and standard of care issues (Albain, Unger, Crowley, Coltman, & Hershman, 2009). A greater understanding of the risk factors and biological links associated with breast cancer, will significantly impact AA communities due to the higher deaths associated with this disease in this population. microRNAs are small noncoding RNA molecules that were recently discovered as major players in the regulation of many diseases including cancer. Although, there are many studies that have investigated the role of miRNAs in breast cancer, few have investigated their role if any in breast cancer disparities. This review serves to summarize the current published literature that is involved in the study of microRNAs and their impact on breast cancer disparities.

MicroRNA-106b targets FUT6 to promote cell migration, invasion, and proliferation in human breast cancer

It is demonstrated that the maladjustment of microRNA (miRNA) plays significant roles in the occurrence and development of tumors. MicroRNA-106b-5p (miR-106b), a carcinogenic miRNA, is identified as a dysregulated miRNA in human breast cancer. In this article, the expression levels of miR-106b were discovered to be particularly higher in breast cancer tissues than that in the corresponding adjacent tissues. Accordingly, miR-106b was higher expressed in the breast cancer cell lines compared with that in the normal breast cell lines. Moreover, according to the data previously reported, increased expression of miR-106b was significantly associated with advanced clinical stages and poor prognosis in breast cancer. Fucosyltransferase 6 (FUT6), a member of the fucosyltransferase (FUT) family, was found to have a reduced expression in tissues or cells with higher level of miR-106b in breast cancer. Additionally, down-regulation of miR-106b increased the expression of FUT6 and resulted in an obvious decrease of cell migration, invasion, and proliferation in MDA-MB-231 cells. Furthermore, over-expressed FUT6 reversed the impacts of up-regulated miR-106b on cell migration, invasion, and proliferation in MCF-7 cells, indicating that FUT6 might be directly targeted by miR-106b and serve as therapeutic targets for breast cancer. In brief, our results strongly showed that the low expression of FUT6 regulated by miR-106b contributed to cell migration, invasion, and proliferation in human breast cancer. © 2016 IUBMB Life, 68(9):764-775, 2016.

MicroRNA-375/SEC23A as biomarkers of the in vitro efficacy of vandetanib

In this study, we performed microRNA (miRNA) expression profiling on a large series of sporadic and hereditary forms of medullary thyroid carcinomas (MTC). More than 60 miRNAs were significantly deregulated in tumor vs adjacent non-tumor tissues, partially overlapping with results of previous studies. We focused our attention on the strongest up-regulated miRNA in MTC samples, miR-375, the deregulation of which has been previously observed in a variety of human malignancies including MTC. We identified miR-375 targets by combining gene expression signatures from human MTC (TT) and normal follicular (Nthy-ori 3-1) cell lines transfected with an antagomiR-375 inhibitor or a miR-375 mimic, respectively, and from an in silico analysis of thyroid cell lines of Cancer Cell Line Encyclopedia datasets. This approach identified SEC23A as a bona fide miR-375 target, which we validated by immunoblotting and immunohistochemistry of non-tumor and pathological thyroid tissue. Furthermore, we observed that miR-375 overexpression was associated with decreased cell proliferation and synergistically increased sensitivity to vandetanib, the clinically relevant treatment of metastatic MTC. We found that miR-375 increased PARP cleavage and decreased AKT phosphorylation, affecting both cell proliferation and viability. We confirmed these results through SEC23A direct silencing in combination with vandetanib, highlighting the importance of SEC23A in the miR-375-associated increased sensitivity to vandetanib.Since the combination of increased expression of miR-375 and decreased expression of SEC23A point to sensitivity to vandetanib, we question if the expression levels of miR-375 and SEC23A should be evaluated as an indicator of eligibility for treatment of MTC patients with vandetanib.

Hsa-miR-375 is a predictor of local control in early stage breast cancer

Background

A long-term analysis by the Early Breast Cancer Trialist Group (EBCTG) revealed a strong correlation between local control and cancer-specific mortality. MicroRNAs (miRs), short (20–25 nucleotides) non-coding RNAs, have been described as prognosticators and predictors for breast cancer in recent years. The aim of the current study was to identify miRs that can predict local control after breast conserving therapy (BCT) in early stage breast cancer.

Results

Clinical data of 46 early stage breast cancer patients with local relapse after BCT were selected from the institutional database. These patients were matched to 101 control patients showing identical clinical features but without local relapse. The study was conducted in two steps. (1) In the pilot study, 32 patients (16 relapses versus 16 controls) were screened for the most de-regulated microRNAs (= candidate microRNAs) in a panel of 1250 miRs by microarray technology. Eight miRs were found to be significantly de-regulated. (2) In the validation study, the candidate microRNAs were analyzed in an independent cohort of 115 patients (30 relapses versus 85 controls) with reverse transcription quantitative polymerase chain reaction (RT-qPCR). From these eight candidates, hsa-miR-375 could be validated. Its median fold change was 2.28 (Mann-Whitney U test, corrected p value = 0.008). In the log-rank analysis, high expression levels of hsa-miR-375 correlated with a significantly higher risk of local relapse (p = 0.003). In a multivariate analysis (forward stepwise regression) including established predictors and prognosticators, hsa-miR-375 was the only variable that was able to distinguish the statistical significance between relapse and control groups (raw p value = 0.000195 HR = 0.76, 95 % CI 0.66–0.88; corrected p value = 0.005).

Conclusions

Hsa-miR-375 predicts local control in patient with early stage breast cancer, especially in estrogen receptor α (ER-α)-positive patients. It can therefore serve as an additional molecular marker for treatment choice independently from known predictors and prognosticators. Validation in larger prospective studies is warranted.

Electronic supplementary material

The online version of this article (doi:10.1186/s13148-016-0198-1) contains supplementary material, which is available to authorized users.

MicroRNA-505 functions as a tumor suppressor in endometrial cancer by targeting TGF-α

Background

Endometrial carcinoma (EC) is one of the most lethal gynecologic cancers. Patients frequently have regional or distant metastasis at diagnosis. MicroRNAs are small non-coding RNAs that participate in numerous biological processes. Recent studies have demonstrated that miR-505 is associated with several types of cancer; however, the expression and function of miR-505 have not been investigated in EC.

Methods

miR-505 expression in normal endometrial tissue, endometrial carcinomas were quantified by Quantitative reverse transcription PCR. The endometrial carcinoma cell lines HEC-1B and Ishikawa were each transfected with miR-505 or scrambled mimics, after which cell phenotype and expression of relevant molecules were assayed. Dual-luciferase reporter assay and a xenograft mouse model were used to examine miR-505 and its target gene TGF-α.

Results

RT-PCR results demonstrated that miR-505 was significantly downregulated in human EC tissues compared to normal endometrial tissues. Besides, miR-505 expression was negatively associated with FIGO stage (stage I-II vs. III-IV), and lymph node metastasis (negative vs. positive). In vitro, overexpression of miR-505 significantly suppressed EC cell proliferation, increased apoptosis and reduced migratory and invasive activity. A miR-505 binding site was identified in the 3′ untranslated region of TGF-α mRNA (TGFA) using miRNA target-detecting software; a dual luciferase reporter assay confirmed that miR-505 directly targets and regulates TGFA. RT-PCR and Western-blotting results indicated that overexpressing miR-505 reduced the expression of TGF-α and the TGF-α-regulated proteins MMP2, MMP9, CDK2, while induced Bax and cleaved-PARP expression in EC cells. In vivo, overexpression of miR-505 reduced the tumorigenicity and inhibited the growth of xenograft tumors in a mouse model of EC.

Conclusions

Taken together, this study demonstrates that miR-505 acts as tumor suppressor in EC by regulating TGF-α.

Electronic supplementary material

The online version of this article (doi:10.1186/s12943-016-0496-4) contains supplementary material, which is available to authorized users.

Noncoding RNAs in breast cancer

The mammalian transcriptome has recently been revealed to encompass a large number of noncoding RNAs (ncRNAs) that play a variety of important regulatory roles in gene expression and other biological processes. MicroRNAs (miRNAs), the best studied of the short noncoding RNAs (sncRNAs), have been extensively characterized with regard to their biogenesis, function and importance in tumorigenesis. Another class of sncRNAs called piwi-interacting RNAs (piRNAs) has also gained attention recently in cancer research owing to their critical role in stem cell regulation. Long noncoding RNAs (lncRNAs) of >200 nucleotides in length have recently emerged as key regulators of developmental processes, including mammary gland development. lncRNA dysregulation has also been implicated in the development of various cancers, including breast cancer. In this review, we describe and discuss the roles of sncRNAs (including miRNAs and piRNAs) and lncRNAs in the initiation and progression of breast tumorigenesis, with a focus on outlining the molecular mechanisms of oncogenic and tumor-suppressor ncRNAs. Moreover, the current and potential future applications of ncRNAs to clinical breast cancer research are also discussed, with an emphasis on ncRNA-based diagnosis, prognosis and future therapeutics.

The Role of MicroRNAs as Predictors of Response to Tamoxifen Treatment in Breast Cancer Patients

Endocrine therapy is a key treatment strategy to control or eradicate hormone-responsive breast cancer. However, resistance to endocrine therapy leads to breast cancer relapse. The recent extension of adjuvant tamoxifen treatment up to 10 years actualizes the need for identifying biological markers that may be used to monitor predictors of treatment response. MicroRNAs are promising biomarkers that may fill the gap between preclinical knowledge and clinical observations regarding endocrine resistance. MicroRNAs regulate gene expression by posttranscriptional repression or degradation of mRNA, most often leading to gene silencing. MicroRNAs have been identified directly in the primary tumor, but also in the circulation of breast cancer patients. The few available studies investigating microRNA in patients suggest that seven microRNAs (miR-10a, miR-26, miR-30c, miR-126a, miR-210, miR-342 and miR-519a) play a role in tamoxifen resistance. Ingenuity Pathway Analysis (IPA) reveals that these seven microRNAs interact more readily with estrogen receptor (ER)-independent pathways than ER-related signaling pathways. Some of these pathways are targetable (e.g., PIK3CA), suggesting that microRNAs as biomarkers of endocrine resistance may have clinical value. Validation of the role of these candidate microRNAs in large prospective studies is warranted.

Comparative microRNA profiling of sporadic and BRCA1 associated basal-like breast cancers

Background

While a number of studies have examined miRNA profiles across the molecular subtypes of breast cancer, it is unclear whether BRCA1 basal-like cancers have a specific miRNA profile. This study aims to compare grade independent miRNA expression in luminal cancers, sporadic and BRCA1 basal-type breast cancers. It also aims to ascertain an immunohistochemical profile regulated by BRCA1 specific miRNAs for potential diagnostic use.

Methods

miRNA expression was assessed in 11 BRCA1 basal, 16 sporadic basal, 17 luminal grade 3 cancers via microarrays. The expression of Cyclin D1, FOXP1, FIH-1, pan-ERβ, NRP1 and CD99, predicted to be regulated by BRCA1 specific miRNAs by computer prediction algorithms, was assessed via immunohistochemistry in a cohort of 35 BRCA1 and 52 sporadic basal-like cancers. Assessment of cyclin D1, FOXP1, NRP1 and CD99 expression was repeated on a validation cohort of 82 BRCA1 and 65 sporadic basal-like breast cancers.

Results

Unsupervised clustering of basal cancers resulted in a “sporadic” cluster of 11 cancers, and a “BRCA1” cluster of 16 cancers, including a subgroup composed entirely of 10 BRCA1 cancers. Compared with sporadic basal cancers, BRCA1 cancers showed reduced positivity for proteins predicted to be regulated by miRNAs: FOXP1 (6/20[30 %] vs. 37/49[76 %], p < 0.001), cyclin D1 (8/22[36 %] vs. 30/46[65 %], p = 0.025), NRP1 (2/20[10 %] vs. 23/46[50 %], p = 0.002). This was confirmed in the validation cohort (all p < 0.001). Negative staining for 2 or more out of FOXP1, cyclin D1 and NRP1 predicts germline BRCA1 mutation with a sensitivity of 92 %, specificity of 44 %, positive predictive value of 38 % and a negative predictive value of 94 %.

Conclusion

Sporadic and BRCA1 basal-like cancers have grade independent miRNA expression profiles. Furthermore miRNA driven differences in the expression of proteins in BRCA1 basal cancers may be detected via immunohistochemistry. These findings may have important diagnostic implications, as immunohistochemical assessment of basal cancers, in addition to the patient’s family and clinical history, may potentially identify patients who may benefit from BRCA1 gene testing.

Electronic supplementary material

The online version of this article (doi:10.1186/s12885-015-1522-4) contains supplementary material, which is available to authorized users.

Combined Label-Free Quantitative Proteomics and microRNA Expression Analysis of Breast Cancer Unravel Molecular Differences with Clinical Implications

Better knowledge of the biology of breast cancer has allowed the use of new targeted therapies, leading to improved outcome. High-throughput technologies allow deepening into the molecular architecture of breast cancer, integrating different levels of information, which is important if it helps in making clinical decisions. microRNA (miRNA) and protein expression profiles were obtained from 71 estrogen receptor-positive (ER(+)) and 25 triple-negative breast cancer (TNBC) samples. RNA and proteins obtained from formalin-fixed, paraffin-embedded tumors were analyzed by RT-qPCR and LC/MS-MS, respectively. We applied probabilistic graphical models representing complex biologic systems as networks, confirming that ER(+) and TNBC subtypes are distinct biologic entities. The integration of miRNA and protein expression data unravels molecular processes that can be related to differences in the genesis and clinical evolution of these types of breast cancer. Our results confirm that TNBC has a unique metabolic profile that may be exploited for therapeutic intervention.

Prognostic value of miR-106b expression in breast cancer patients

BACKGROUND

The aim of the present study was to evaluate whether the level of expression of tissue or plasma miR-106b can be used to predict clinical outcomes in breast cancer patients.

METHODS

Both tissue and plasma samples were collected and analyzed from 173 patients with primary breast cancer and a set of 50 women with fibroadenoma. The relative expression levels of miR-106b were determined using real-time quantitative reverse transcription polymerase chain reaction and in situ hybridization.

RESULTS

The levels of miR-106b were upregulated in both tissue and plasma samples from breast cancer patients. The expression levels showed a linear correlation (rs = 0.748, P < 0.001) and were significantly correlated with tumor size, Ki67 expression, and lymph node metastasis (all P < 0.05). Patients with high miR-106b expression levels tended to have shorter disease-free survival times and overall survival times (P < 0.001). In a Cox regression model, high-level tissue and plasma miR-106b expression were unfavorable prognostic factors, and receiver-operating characteristic analysis revealed that the tissue and plasma miR-106b levels provided considerable diagnostic accuracy, yielding an area under the ROC curve of 0.785 and 0.856, respectively.

CONCLUSIONS

MiR-106b was found to be associated with a high risk of recurrence of breast cancer, and miR-106b is a putative plasma marker for risk assessment in patients with breast cancer.

microRNAs: a new class of breast cancer biomarkers

MicroRNAs (miRNAs) are regulatory molecules known to be aberrantly expressed in cancer and contribute to numerous aspects of tumor biology including the initiation, growth and spread of the tumor. With such diverse roles, it is becoming apparent that some may also provide valuable information which may be of use in a clinical setting, demonstrating the potential to act as both screening tools for the stratification of high-risk patients, while informing the treatment decision-making process. There is mounting evidence to suggest that some miRNAs may even provide assistance in the diagnosis of patients with breast cancer. In addition, miRNAs may themselves be considered therapeutic targets, with inhibition or reintroduction of a particular miRNA capable of inducing a response in vivo. This review focuses on miRNAs that have prognostic, diagnostic or predictive potential in breast cancer as well as the possible challenges in the translation of such observations to the clinic.

An ER-associated miRNA signature predicts prognosis in ER-positive breast cancer

Background

Breast cancer patients with positive estrogen receptor (ER) have a better prognosis. However, no prognostic miRNA signature was reported in the ER-positive breast cancer. The aim of the study was to identify and assess the prognostic significance of a miRNA signature in ER-positive breast cancer.

Methods

Two cohorts from The Cancer Genome Atlas (TCGA) dataset were used as training (n =596) and testing set (n =319). Differential expression profiling was identified in the training set. And the prognostic value of the miRNA signature was then assessed in the two cohorts.

Results

A total of 14 miRNAs were observed to be associated with the status of ER by significance analysis of microarrays (SAM) in the training set. Patients were characterized as high score or low score group according to the calculated risk scores from each miRNA. And patients in high score group had worse overall survival compared with those in low score group both in the training and testing set.

Conclusions

Our study revealed a miRNA signature including 14 miRNAs associated with ER status which could act as a prognostic marker in ER-positive breast cancer.

Electronic supplementary material

The online version of this article (doi:10.1186/s13046-014-0094-5) contains supplementary material, which is available to authorized users.

Prognostic significance of microRNA-375 downregulation in solid tumors: a meta-analysis

Objective. Recently, many studies have shown that microRNAs (miRNA) exhibit altered expression in various cancers and may play an important role as prognostic biomarker of cancers. We performed a meta-analysis to evaluate the impact of miR-375 expression in solid tumors on patients' overall survival (OS). Methods. Studies were identified by searching PubMed, Embace, and Cochrane Library (last search update was in May 2014) and were assessed by further quality evaluation. The pooled hazard ratios (HRs) with 95% confidence intervals (CIs) for total and stratified analyses were calculated to investigate the association between miR-375 expression and cancer patients OS. Results. Our analysis results indicated that downregulation of miR-375 predicted poor OS (HR = 1.91, 95% CI 1.48–2.45, P < 0.001). Subgroup analyses showed that lower expression of miR-375 was significantly related with poor OS in patients with esophageal carcinoma (HR = 2.24, 95% CI 1.69–2.96, P < 0.001) and non-small-cell lung cancer (NSCLC) (HR = 1.71, 95% CI 1.31–2.24, P < 0.001). Conclusions. The findings from this meta-analysis suggest that miR-375 expression is associated with OS of patients with malignant tumors and could be a useful clinical prognostic biomarker.

The role of miR-200a in mammalian epithelial cell transformation

Cancer is a multistep disease that begins with malignant cell transformation and frequently culminates in metastasis. MicroRNAs (miRNAs) are small regulatory 21-25 nt RNA molecules and are frequently deregulated in cancer. miR-200a is a member of the miR-200 family, which are known inhibitors of the epithelial-to-mesenchymal transition. As such, the tumor-suppressive role of miR-200a in oncogenesis has been well documented; however, recent studies have found a proliferative role for this miRNA as well as a prometastatic role in the later steps of cancer progression. Little is known about the role of this miRNA in the early stages of cancer, namely, malignant cell transformation. Here, we show that miR-200a alone transforms an immortalized rat epithelial cell line, and miR-200a cooperates with Ras to enhance malignant transformation of an immortalized human epithelial cell line. Furthermore, miR-200a induces cell transformation and tumorigenesis in immunocompromised mice by cooperating with a Ras mutant that activates only the RalGEF effector pathway, but not Ras mutants activating PI3K or Raf effector pathways. This transformative ability is in accordance with miR-200a targeting Fog2 and p53 to activate Akt and directly repress p53 protein levels, respectively. These results demonstrate an oncogenic role for miR-200a and provide a specific cellular context where miR-200a acts as an oncomiR rather than a tumor suppressor by cooperating with an oncogene in malignant cell transformation.

SHOX2 is a direct miR-375 target and a novel epithelial-to-mesenchymal transition inducer in breast cancer cells

MicroRNAs have added a new dimension to our understanding of tumorigenesis and associated processes like epithelial-to-mesenchymal transition (EMT). Here, we show that miR-375 is elevated in epithelial-like breast cancer cells, and ectopic miR-375 expression suppresses EMT in mesenchymal-like breast cancer cells. We identified short stature homeobox 2 (SHOX2) as a miR-375 target, and miR-375-mediated suppression in EMT was reversed by forced SHOX2 expression. Ectopic SHOX2 expression can induce EMT in epithelial-like breast cancer cells, whereas SHOX2 knockdown diminishes EMT traits in mesenchymal-like breast cancer cells, demonstrating SHOX2 as an EMT inducer. We show that SHOX2 acts as a transcription factor to upregulate transforming growth factor β receptor I (TβR-I) expression, and TβR-I inhibitor LY364947 abolishes EMT elicited by ectopic SHOX2 expression, suggesting that transforming growth factor β signaling is essential for SHOX2-induced EMT. Manipulating SHOX2 abundance in breast cancer cells impact in vitro invasion and in vivo dissemination. Analysis of breast tumor microarray database revealed that high SHOX2 expression significantly correlates with poor patient survival. Our study supports a critical role of SHOX2 in breast tumorigenicity.

MiR-216a and miR-216b as markers for acute phased pancreatic injury

MicroRNAs (miRNAs) are endogenous small RNAs (length, 18-ss23 nucleotides) that regulate gene expression. Recently, plasma miRNAs have been investigated as biomarkers for various diseases. In the present study, we explored cell- or tissue-specific miRNAs and assessed the applicability of miRNA profiling for identifying biomarkers of tissue injuries. miRNA analyses in various human and rat tissues identified several candidate miRNAs with possible tissue-specific expression, some of which have already been reported. In the present study, we focused on pancreas-specific miRNAs, miR-216a and miR-216b. Laser microdissection revealed that miR-216a and 216b were predominantly expressed in acinar cells of the pancreas as compared to Langerhans' islet. Plasma concentrations of miR-216a and miR-216b considerably increased in a rat model of L-arginineinduced acute pancreatitis. The current results have confirmed that miRNA expression profiling in various cells is useful for providing biomarkers for cell- or tissue-specific injuries.

The emerging role of miR-375 in cancer

MicroRNAs (miRNAs) are evolutionarily conserved, small noncoding RNAs that are believed to play fundamental roles in various biological processes through regulation of gene expression at the level of posttranscription. MiR-375 was first identified as a pancreatic islet-specific miRNA regulating insulin secretion. However, further study revealed that miR-375 is a multifunctional miRNA participating in pancreatic islet development, glucose homeostasis, mucosal immunity, lung surfactant secretion and more importantly, tumorigenesis. Recently, miR-375 has been found significantly downregulated in multiple types of cancer, and suppresses core hallmarks of cancer by targeting several important oncogenes like AEG-1, YAP1, IGF1R and PDK1. The alteration of miR-375 in cancer is caused by a variety of mechanisms, including the dysregulation of transcription factors, aberrant promoter methylation and so on. Reduced expression of miR-375 in tissue or circulation may indicate the presence of neoplasia as well as a poor prognosis of many malignant cancers. Moreover, miR-375 stands for a promising direction for developing targeted therapies due to its capacity to inhibit tumor cell growth in vitro and in vivo. Here, we summarize the present understanding of the tumor suppressive role of miR-375 in cancer progression; the mechanisms underlying the dysregulation of miR-375; the potential use of miR-375 in prognosis and diagnosis and the therapeutic prospects of miR-375 in cancer.

microRNA-18b is upregulated in breast cancer and modulates genes involved in cell migration

microRNAs are small non-coding RNAs of ~22 nucleotides that function at post-transcriptional level as negative regulators of gene expression. Aberrant expression of microRNAs could promote uncontrolled proliferation, migration and invasion of human cancer cells. In this study, we analyzed the expression of microRNA-18b (miR-18b) in breast cancer cell lines and in a set of clinical specimens. Our results showed that miR-18b was upregulated in four out of five breast cancer cell lines and also in breast tumors. In order to identify potential gene targets, we carried out transcriptional profiling of MDA-MB-231 breast cancer cells that ectopically expressed miR-18b. Our results showed that 263 genes were significantly modulated in miR-18b-deficient cells (fold change >1.5; P≤0.05). We found that knock-down of miR-18b induced the upregulation of 55 olfactory receptor (OR) genes and nine genes (NLRP7, KLK3, OLFM3, POSTN, MAGED4B, KIR3DL3, CRX, SEMG1 and CEACAM5) with key roles in cell migration and metastasis. Consistently, we found that ectopic inhibition of miR-18b suppressed the migration of two breast cancer cell models in vitro. In conclusion, we have uncovered genes directly or indirectly modulated by miR-18b which may represent potential therapeutic targets in breast cancer. Our data also pointed out a role of miR-18b in migration of breast cancer cells.