miR-10b targets Tiam1: implications for Rac activation and carcinoma migration

Photoactivatable Nanobody Conjugate Dimerizer Temporally Resolves Tiam1-Rac1 Signaling Axis

The precise spatiotemporal dynamics of protein activities play a crucial role in cell signaling pathways. To control cellular functions in a spatiotemporal manner, a powerful method called photoactivatable chemically induced dimerization (pCID) is used. In this study, photoactivatable nanobody conjugate inducers of dimerization (PANCIDs) is introduced, which combine pCID with nanobody technology. A PANCID consists of a nanobody module that directly binds to an antigenic target, a photocaged small molecule ligand, and a cyclic decaarginine (cR10 *) cell-penetrating peptide (CPP) for efficient nonendocytic intracellular delivery. Therefore, PANCID photodimerizers also benefit from nanobodies, such as their high affinities (in the nm or pm range), specificities, and ability to modulate endogenous proteins. Additionally it is demonstrated that the nanobody moiety can be easily replaced with alternative ones, expanding the potential applications. By using PANCIDs, the dynamics of the Tiam1-Rac1 signaling cascade is investigated and made an interesting finding. It is found that Rac1 and Tiam1 exhibit distinct behaviors in this axis, acting as time-resolved "molecular oscillators" that transit between different functions in the signaling cascade when activated either slowly or rapidly.

Effective exosomes in breast cancer: focusing on diagnosis and treatment of cancer progression

Breast cancer (BC) is the most prevalent aggressive malignant tumor in women worldwide and develops from breast tissue. Although cutting-edge treatment methods have been used and current mortality rates have decreased, BC control is still not satisfactory. Clarifying the underlying molecular mechanisms will help clinical options. Extracellular vesicles known as exosomes mediate cellular communication by delivering a variety of biomolecules, including proteins, oncogenes, oncomiRs, and even pharmacological substances. These transferable bioactive molecules can alter the transcriptome of target cells and affect signaling pathways that are related to tumors. Numerous studies have linked exosomes to BC biology, including therapeutic resistance and the local microenvironment. Exosomes' roles in tumor treatment resistance, invasion, and BC metastasis are the main topics of discussion in this review.

Co-administration of temozolomide (TMZ) and the experimental therapeutic targeting miR-10b, profoundly affects the tumorigenic phenotype of human glioblastoma cells

Introduction: Recent studies have shown that miRNA-10b is highly expressed in high-grade glioblastoma multiforme (GBM), and its inhibition leads to deregulation of multiple pathways in tumorigenesis, resulting in repression of tumor growth and increased apoptosis. Thus, we hypothesized that suppressing miR-10b could enhance the cytotoxicity of conventional GBM chemotherapy with temozolomide (TMZ). Methods: Inhibition of miR-10b in glioblastoma cells was achieved using an experimental therapeutic consisting of anti-miR10b antagomirs conjugated to iron oxide nanoparticles (termed MN-anti-miR10b). The nanoparticles serve as delivery vehicles for the antagomirs as well as imaging reporters guiding the delivery in future animal studies. Results: Treatment of U251 and LN229 human glioblastoma cells with MN-anti-miR10b led to inhibition of miR-10b accompanied by repression of growth and increase in apoptosis. We next explored whether MN-anti-miR10b could enhance the cytotoxic effect of TMZ. During these studies, we unexpectedly found that TMZ monotherapy increased miR-10b expression and changed the expression of corresponding miR-10b targets. This discovery led to the design of a sequence-dependent combination treatment, in which miR-10b inhibition and induction of apoptosis by MN-anti-miR10b was followed by a sub-therapeutic dose of TMZ, which caused cell cycle arrest and ultimately cell death. This combination was highly successful in significant enhancement of apoptosis and decrease in cell migration and invasiveness. Discussion: Considering the unexpected effects of TMZ on miR-10b expression and possible implications on its clinical application, we reasoned that comprehensive in vitro studies were warranted before embarking on studies in animals. These intriguing findings serve as a solid foundation for future in vivo studies and offer promise for the successful treatment of GBM.

Overview of non-coding RNAs in breast cancers

Breast cancer in women is the second most common cancer and the fifth leading cause of cancer death worldwide. Although earlier diagnosis and detection of breast cancer has resulted in lower mortality rates, further advances in prevention, detection, and treatment are needed to improve outcomes and survival for women with breast cancer as well as to offer a personalized therapeutic approach. It is now well-established that non-coding RNAs (ncRNAs) represent 98% of the transcriptome but in-depth knowledge about their involvement in the regulation of gene expression is lacking. A growing body of research indicates that ncRNAs are essential for tumorigenesis by regulating the expression of tumour-related genes. In this review, we focus on their implication in breast cancer genesis but also report the latest knowledge of their theragnostic and therapeutic role. We highlight the need for accurate quantification of circulating ncRNAs which is determinant to develop reliable biomarkers. Further studies are mandatory to finally enter the era of personalized medicine for women with breast cancer.

MiR-10b-5p inhibits tumorigenesis in gastric cancer xenograft mice model through down-regulating Tiam1

The miR-10b-5p plays an important role in gastric cancer development but its exact effect on gastric cancer development in vivo has not been fully studied. We showed that miR-10b-5p inhibited the proliferation and migration of gastric cancer cells by down-regulating Tiam1 which was up-regulated in both gastric cancer cells and tissues. Gastric cancer xenograft experiment showed that lenti-miR-10b-5p treatment and agomir-10b-5p injection could significantly retard tumor growth and reduce tumor size and induced apoptosis. Therefore, our results elucidate the tumor suppressor role of miR-10b-5p in gastric cancer in which it acts as a negative regulator of Tiam1 and also provide a molecular mechanism for agomir-10b-5p to treat gastric cancer.

MicroRNA‑10b modulates cisplatin tolerance by targeting p53 directly in lung cancer cells

MicroRNA (miRNA or miR)‑10b is an oncogenic miRNA associated with metastasis that is present in various types of tumor, including lung cancer. However, whether miR‑10b is involved in different malignant characteristics, such as drug resistance or stemness, remains unclear. Therefore, the present study investigated whether miR‑10b is an upstream regulator of p53. Ectopic expression of miR‑10b‑agomir decreased the expression of p53 and its downstream effectors, such as Bax and p53 upregulated modulator of apoptosis. Two non‑canonical sites, including 1,580‑1,587 and 2,029‑2,035, located in p53 3'‑untranslated region (UTR) were affected by the presence of miR‑10b. In functional assays, upregulation of the p53 signaling pathway following cisplatin treatment was associated with decreased levels of miR‑10b and upregulation of the luciferase activity of wild‑type, but not 1,584, 2,032‑dual‑mutant, p53 3'‑UTR. The ectopic expression of miR‑10b‑agomir attenuated the stability of p53 3'‑UTR and the expression of p53 and its downstream effectors induced by cisplatin. By contrast, the knockdown of miR‑10b induced the stability of p53 3'‑UTR and increased levels of p53 and the sensitivity of A549 cells to cisplatin treatment. Similar results were also observed for Beas 2B cells. In the clinical investigation, p53 exhibited two distinct associations (cocurrent and countercurrent) with miR‑10b in patients with lung cancer. Patients with lung cancer with low p53 and high miR‑10b levels exhibited the poorest prognosis, while those with high p53 and low miR‑10b exhibited the most favorable prognosis. These findings indicate a novel pathway in which cisplatin induces the levels of p53 by increasing mRNA stability via miR‑10b, indicating a novel oncogenic role of miR‑10b in promoting the malignant characteristics of non‑small cell lung carcinoma.

miRNAs: Critical mediators of breast cancer metastatic programming

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

MicroRNA Regulation of the Small Rho GTPase Regulators-Complexities and Opportunities in Targeting Cancer Metastasis

The small Rho GTPases regulate important cellular processes that affect cancer metastasis, such as cell survival and proliferation, actin dynamics, adhesion, migration, invasion and transcriptional activation. The Rho GTPases function as molecular switches cycling between an active GTP-bound and inactive guanosine diphosphate (GDP)-bound conformation. It is known that Rho GTPase activities are mainly regulated by guanine nucleotide exchange factors (RhoGEFs), GTPase-activating proteins (RhoGAPs), GDP dissociation inhibitors (RhoGDIs) and guanine nucleotide exchange modifiers (GEMs). These Rho GTPase regulators are often dysregulated in cancer; however, the underlying mechanisms are not well understood. MicroRNAs (miRNAs), a large family of small non-coding RNAs that negatively regulate protein-coding gene expression, have been shown to play important roles in cancer metastasis. Recent studies showed that miRNAs are capable of directly targeting RhoGAPs, RhoGEFs, and RhoGDIs, and regulate the activities of Rho GTPases. This not only provides new evidence for the critical role of miRNA dysregulation in cancer metastasis, it also reveals novel mechanisms for Rho GTPase regulation. This review summarizes recent exciting findings showing that miRNAs play important roles in regulating Rho GTPase regulators (RhoGEFs, RhoGAPs, RhoGDIs), thus affecting Rho GTPase activities and cancer metastasis. The potential opportunities and challenges for targeting miRNAs and Rho GTPase regulators in treating cancer metastasis are also discussed. A comprehensive list of the currently validated miRNA-targeting of small Rho GTPase regulators is presented as a reference resource.

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

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

MicroRNA-10b controls the metastasis and proliferation of colorectal cancer cells by regulating Krüppel-like factor 4

Mir-10b has been reported as a key regulator of metastasis in many human tumours. Moreover, it has also been regarded as a prognostic marker and therapeutic target of colorectal cancer (CRC). Whether miR-10b could affect the metastasis and proliferation of CRC is unclear. MiR-10b expression was detected by qPCR in human CRC tissues and cell line, Luciferase activity was employed for miR-10b binding to the 3`UTR of KLF4, Genes expression were examined by western blot, and mRNA by qPCR. PI and Annexin V staining were used to evaluate the cell cycle and apoptosis. Cell proliferation was detected with MTT, and cell migration and invasion were performed with Transwell assay. We found that miR-10b expression was up-regulated in metastatic CRC tissues and cell lines. Inhibition of miR-10b prevented cancer cell metastasis and growth by inducing cell-cycle arrest and apoptosis in vitro. Moreover, we found that KLF4 was a direct target of miR-10b. MiR-10b inhibitor led to the up-regulation of E-cadherin expression and the down-regulation of cyclin D1, which were partly abrogated after silencing KLF4.

Triple Negative Breast Cancer Profile, from Gene to microRNA, in Relation to Ethnicity

Breast cancer is the most frequent cause of cancer-related deaths among women worldwide. It is classified into four major molecular subtypes. Triple-negative breast cancers (TNBCs), a subgroup of breast cancer, are defined by the absence of estrogen and progesterone receptors and the lack of HER-2 expression; this subgroup accounts for ~15% of all breast cancers and exhibits the most aggressive metastatic behavior. Currently, very limited targeted therapies exist for the treatment of patients with TNBCs. On the other hand, it is important to highlight that knowledge of the molecular biology of breast cancer has recently changed the decision-making process regarding the course of cancer therapies. Thus, a number of new techniques, such as gene profiling and sequencing, proteomics, and microRNA analysis have been used to explore human breast carcinogenesis and metastasis including TNBC, which consequently could lead to new therapies. Nevertheless, based on evidence thus far, genomics profiles (gene and miRNA) can differ from one geographic location to another as well as in different ethnic groups. This review provides a comprehensive and updated information on the genomics profile alterations associated with TNBC pathogenesis associated with different ethnic backgrounds.

Discovery of 5-Signature Predicting Survival of Patients with Lower-Grade Glioma

OBJECTIVE

In the study, we aimed to identify key microRNAs (miRNAs) and clinical factors associated with survival time of lower-grade glioma (LGG) and develop an expression-based miRNA signature to provide survival risk prediction for patients with LGG.

METHODS

We obtained miRNA expression profiles and clinical information of patients with LGG from The Cancer Genome Atlas dataset. All 591 miRNAs were modeled using random Forest Survival, Regression, and Classification to construct a random forest model for survival analysis, and feature selection was performed. We used univariate and multivariate Cox regression analysis to screen differentially expressed miRNAs and clinical factors related to overall survival of patients with LGG.

RESULTS

A total of 591 differentially expressed miRNAs were obtained between LGG and normal tissues. After univariate and multivariate Cox regression analysis, 2 predictive miRNAs (hsa-miR-10b-5p and hsa-miR-15b-5p) and 3 clinical factors (grade, age, and cancer status) were finally screened out to construct a 5-signature, based on which patients in the training dataset were divided into high-risk and low-risk groups. The competitive performance of the 5-signature was revealed by receiver operating characteristic curve analysis. The prognostic value of the 5-signature was successfully validated in the testing and validation dataset.

CONCLUSIONS

Our study demonstrated the promising potential of the novel 5-signature as an independent biomarker for survival prediction of patients with LGG.

Emerging ways to treat breast cancer: will promises be met?

BACKGROUND

Breast cancer (BC) is the most common cancer among women and it is responsible for more than 40,000 deaths in the United States and more than 500,000 deaths worldwide each year. In previous decades, the development of improved screening, diagnosis and treatment methods has led to decreases in BC mortality rates. More recently, novel targeted therapeutic options, such as the use of monoclonal antibodies and small molecule inhibitors that target specific cancer cell-related components, have been developed. These components include ErbB family members (HER1, HER2, HER3 and HER4), Ras/MAPK pathway components (Ras, Raf, MEK and ERK), VEGF family members (VEGFA, VEGFB, VEGFC, VEGF and PGF), apoptosis and cell cycle regulators (BAK, BAX, BCL-2, BCL-X, MCL-1 and BCL-W, p53 and PI3K/Akt/mTOR pathway components) and DNA repair pathway components such as BRCA1. In addition, long noncoding RNA inhibitor-, microRNA inhibitor/mimic- and immunotherapy-based approaches are being developed for the treatment of BC. Finally, a novel powerful technique called CRISPR-Cas9-based gene editing is emerging as a precise tool for the targeted treatment of cancer, including BC.

CONCLUSIONS

Potential new strategies that are designed to specifically target BC are presented. Several clinical trials using these strategies are already in progress and have shown promising results, but inherent limitations such as off-target effects and low delivery efficiencies still have to be resolved. By improving the clinical efficacy of current therapies and exploring new ones, it is anticipated that novel ways to overcome BC may become attainable.

The fundamental role of miR-10b in metastatic cancer

Small, non-coding strands of RNA have been identified as a significant player in the pathology of cancer. One of the first miRNAs to be shown as having aberrant expression in cancer was miR-10b. Since the inaugural study on miR-10b, its role as a metastasis promoting factor has been extensively validated. To date, more than 100 studies have been completed on miR-10b and metastasis across 18 cancer types. This immense set of information holds possibilities for novel methods to improve the lives of many. This review outlines what is currently understood of miR-10b's clinical significance, its molecular regulation, and the possible diagnostic and therapeutic methods leveraging miR-10b as a fundamental target in metastatic cancer. Such methods would move us closer to developing a truly individualized therapeutic strategy against cancer and will likely provide unique information about cancer staging, disease outcome, metastatic potential, and ultimately survival.

MicroRNA 483-3p targets Pard3 to potentiate TGF-β1-induced cell migration, invasion, and epithelial-mesenchymal transition in anaplastic thyroid cancer cells

Anaplastic thyroid cancer (ATC) is associated with poor prognosis and is often untreatable. MicroRNA 483-3p (miR-483) and partitioning-defective 3 (Pard3), a member of the Pard family, have functions and regulatory mechanisms in ATC. The abnormal regulation of miR-483 may play an important role in tumorigenesis, and Par3 is known to regulate cell polarity, cell migration, and cell division. Tumor proliferation promoted by the regulation of miRNA expression can be regulated in thyroid cancer by upregulating transforming growth factor-β1 (TGF-β1), which is thought to interact with Pard3. When compared with adjacent non-tumor tissues, we found that miR-483 was upregulated and Pard3 was downregulated in 80 thyroid tumor samples. Disease-free survival was decreased when expression of miR-483 was upregulated and Pard3 expression was downregulated. Cell growth, migration, and invasion were induced by overexpression of miR-483. However, knockdown of miR-483 resulted in a loss of cell invasion and viability, both in vitro and in vivo. The expression of Pard3 was increased by the inhibition of miR-483, but TGF-β1-induced cell migration and invasion were decreased by miR-483 inhibition. A dual-luciferase reporter assay determined that Pard3 expression was downregulated when targeted with miR-483. The epithelial–mesenchymal transition (EMT), as well as Tiam1-Rac signaling, was induced by TGF-β1, which was decreased by the overexpression of Pard3. Pard3 decreased the inhibition of EMT and Tiam-Rac1 signaling, which resulted from transfection of ATC cells with miR-483. Overall, the results showed that downregulation of Pard3 resulted in increased cell invasion and EMT in ATC, which was promoted by treatment with miR-483. These findings suggest novel therapeutic targets and treatment strategies for this disease.

Recurrence prediction using microRNA expression in hormone receptor positive breast cancer during tamoxifen treatment

PURPOSE

To identify miRNAs associated with distant recurrence during tamoxifen treatment and build a recurrence prediction model.

MATERIALS AND METHODS

We measured the expression of five miRNAs (miR-134, miR-125b-5P, miRNA-30a, miR-10a-5p and miR-222). A total of 176 tumour tissues from 176 patients who had hormone receptor positive breast cancer with tamoxifen treatment were used to measure miRNA expression using quantitative real-time PCR (qRT-PCR).

RESULTS

The five miRNAs were all up-regulated in distant recurrence cases within 5 years after surgery and during tamoxifen treatment. Kaplan-Meier survival analyses based on expression cut-offs determined by receiver characteristics curves (ROC) showed that high expression of miR-134, miR-125b-5P, miRNA-30a, miR-10a-5p and miR-222 were significantly (log-rank p-value =0.006, p-value <0.0001, p-value <0.0001, p-value <0.0001 and p-value <0.0001, respectively) associated with short relapse-free time. Our results were used to build a combined 3 miRNAs expression model. It could be used to categorize high-risk subset of patients with short relapse-free survival (AUC =0.891, p-value <0.0001).

CONCLUSIONS

Distant recurrence during tamoxifen treatment of hormone positive breast cancer might be affected by tamoxifen resistance related miRNAs. Such distant recurrence can be predicted using miRNA measurement.

Potent and selective effect of the mir-10b inhibitor MN-anti-mir10b in human cancer cells of diverse primary disease origin

Since microRNAs (miRNAs, miRs) have been implicated in oncogenesis, many of them have been identified as therapeutic targets. Previously we have demonstrated that miRNA-10b acts as a master regulator of the viability of metastatic tumor cells and represents a target for therapeutic intervention. We designed and synthesized an inhibitor of miR-10b, termed MN-anti-miR10b. We showed that treatment with MN-anti-miR10b led to durable regression/elimination of established metastases in murine models of metastatic breast cancer. Since miRNA-10b has been associated with various metastatic and non-metastatic cancers, in the present study, we investigated the effect of MN-anti-miR10b in a panel of over 600 cell lines derived from a variety of human malignancies. We observed an effect on the viability of multiple cell lines within each cancer type and a mostly dichotomous response with cell lines either strongly responsive to MN-anti-miR10b or not at all even at maximum dose tested, suggesting a very high specificity of the effect. Genomic modeling of the drug response showed enrichment of genes associated with the proto-oncogene, c-Jun.

New Directions in the Study and Treatment of Metastatic Cancer

Traditional cancer therapy has relied on a strictly cytotoxic approach that views non-metastatic and metastatic tumor cells as identical in terms of molecular biology and sensitivity to therapeutic intervention. Mounting evidence suggests that, in fact, non-metastatic and metastatic tumor cells differ in key characteristics that could explain the capacity of the metastatic cells to not only escape the primary organ but also to survive while in the circulation and to colonize a distant organ. Here, we lay out a framework for a new multi-pronged therapeutic approach. This approach involves modifying the local microenvironment of the primary tumor to inhibit the formation and release of metastatic cells; normalizing the microenvironment of the metastatic organ to limit the capacity of metastatic tumor cells to invade and colonize the organ; remediating the immune response to tumor neoantigens; and targeting metastatic tumor cells on a systemic level by restoring critical and unique aspects of the cell’s phenotype, such as anchorage dependence. Given the limited progress against metastatic cancer using traditional therapeutic strategies, the outlined paradigm could provide a more rational alternative to patients with metastatic cancer.

VEGF-neuropilin-2 signaling promotes stem-like traits in breast cancer cells by TAZ-mediated repression of the Rac GAP β2-chimaerin

The role of vascular endothelial growth factor (VEGF) signaling in cancer is not only well known in the context of angiogenesis but also important in the functional regulation of tumor cells. Autocrine VEGF signaling mediated by its co-receptors called neuropilins (NRPs) appears to be essential for sustaining the proliferation and survival of cancer stem cells (CSCs), which are implicated in mediating tumor growth, progression, and drug resistance. Therefore, understanding the mechanisms involved in VEGF-mediated support of CSCs is critical to successfully treating cancer patients. The expression of the Hippo effector TAZ is associated with breast CSCs and confers stem cell-like properties. We found that VEGF-NRP2 signaling contributed to the activation of TAZ in various breast cancer cells, which mediated a positive feedback loop that promoted mammosphere formation. VEGF-NRP2 signaling activated the GTPase Rac1, which inhibited the Hippo kinase LATS, thus leading to TAZ activity. In a complex with the transcription factor TEAD, TAZ then bound and repressed the promoter of the gene encoding the Rac GTPase-activating protein (Rac GAP) β2-chimaerin. By activating GTP hydrolysis, Rac GAPs effectively turn off Rac signaling; hence, the TAZ-mediated repression of β2-chimaerin resulted in sustained Rac1 activity in CSCs. Depletion of β2-chimaerin in non-CSCs increased Rac1 activity, TAZ abundance, and mammosphere formation. Analysis of a breast cancer patient database revealed an inverse correlation between β2-chimaerin and TAZ expression in tumors. Our findings highlight an unexpected role for β2-chimaerin in a feed-forward loop of TAZ activation and the acquisition of CSC properties.

MicroRNA and HER2-overexpressing cancer

The discovery of microRNAs (miRNAs) has opened up new avenues for studying cancer at the molecular level, featuring a post-genomic era of biomedical research. These non-coding regulatory RNA molecules of ~22 nucleotides have emerged as important cancer biomarkers, effectors, and targets. In this review, we focus on the dysregulated biogenesis and function of miRNAs in cancers with an overexpression of the proto-oncogene HER2. Many of the studies reviewed here were carried out in breast cancer, where HER2 overexpression has been extensively studied and HER2-targeted therapy practiced for more than a decade. MiRNA signatures that can be used to classify tumors with different HER2 status have been reported but little consensus can be established among various studies, emphasizing the needs for additional well-controlled profiling approaches and meta-analyses in large and well-balanced patient cohorts. We further discuss three aspects of microRNA dysregulation in or contribution to HER2-associated malignancies or therapies: (a) miRNAs that are up- or down-regulated by HER2 and mediate the downstream signaling of HER2; (b) miRNAs that suppress the expression of HER2 or a factor in HER2 receptor complexes, such as HER3; and (c) miRNAs that affect responses to anti-HER2 therapies. The regulatory mechanisms are elaborated using mainly examples of miR-205, miR-125, and miR-21. Understanding the regulation and function of miRNAs in HER2-overexpressing tumors shall shed new light on the pathogenic mechanisms of microRNAs and the HER2 proto-oncogene in cancer, as well as on individualized or combinatorial anti-HER2 therapies.

MicroRNAs in Breast Cancer: Diagnostic and Therapeutic Potential

MicroRNAs (miRNAs) are a large family of small, approximately 20-22 nucleotide, noncoding RNAs that regulate the expression of target genes, at the post-transcriptional level. miRNAs are involved in virtually diverse biological processes and play crucial roles in cellular processes, such as cell differentiation, proliferation, and apoptosis. Accumulating lines of evidence have indicated that miRNAs play important roles in the maintenance of biological homeostasis and that aberrant expression levels of miRNAs are associated with the onset of many diseases, including cancer. It is possible that the diverse roles that miRNAs play, have potential to provide valuable information 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. Increasing evidence suggests 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 chapter discusses the role of miRNAs as oncogenes and tumor suppressors in breast cancer development and metastasis . It 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.

Therapeutic impacts of microRNAs in breast cancer by their roles in regulating processes involved in this disease

Breast cancer is the most common cancer in women around the world. So far, many attempts have been made to treat this disease, but few effective treatments have been discovered. In this work, we reviewed the related articles in the limited period of time, 2000-2016, through search in PubMed, Scopus database, Google Scholar, and psychology and psychiatry literature (PsycINFO). We selected the articles about the correlation of microRNAs (miRNAs) and breast cancer in the insight into therapeutic applicability from mentioned genetics research databases. The miRNAs as an effective therapy for breast cancer was at the center of our attention. Hormone therapy and chemotherapy are two major methods that are being used frequently in breast cancer treatment. In the search for an effective therapy for breast cancer, miRNAs suggest a promising method of treatment. miRNAs are small, noncoding RNAs that can turn genes on or off and can have critical roles in cancer treatment; therefore, in the near future, usage of these biological molecules in breast cancer treatment can be considered a weapon against most common cancer-related concerns in women. Here, we discuss miRNAs and their roles in various aspects of breast cancer treatment to help find an alternative and effective way to treat or even cure this preventable disease.

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

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

Tumor microenvironment and noncoding RNAs as co-drivers of epithelial-mesenchymal transition and cancer metastasis

Reciprocal interactions between cancer cells and tumor microenvironment (TME) are crucial events in tumor progression and metastasis. Pervasive stromal reprogramming of TME modifies numerous cellular functions, including extracellular matrix (ECM) stiffness, inflammation, and immunity. These environmental factors allow selection of more aggressive cells that develop adaptive strategies associating plasticity and epithelial-mesenchymal transition (EMT), stem-like phenotype, invasion, immunosuppression, and resistance to therapies. EMT is a morphomolecular process that endows epithelial tumor cells with mesenchymal properties, including reduced adhesion and increased motility. Numerous studies have demonstrated involvement of noncoding RNAs (ncRNAs), such as miRNAs and lncRNAs, in tumor initiation, progression, and metastasis. NcRNAs regulate every hallmark of cancer and have now emerged as new players in induction and regulation of EMT. The reciprocal regulatory interactions between ncRNAs, TME components, and cancer cells increase the complexity of gene expression and protein translation in cancer. Thus, deeper understanding of molecular mechanisms controlling EMT will not only shed light on metastatic processes of cancer cells, but enhance development of new therapies targeting metastasis. In this review, we will provide recent findings on the role of known ncRNAs relevant to EMT and cancer metastasis and discuss the role of the interaction between ncRNAs and TME as co-drivers of EMT. Developmental Dynamics 247:405-431, 2018. © 2017 Wiley Periodicals, Inc.

miRNA Regulation in Gliomas: Usual Suspects in Glial Tumorigenesis and Evolving Clinical Applications

In recent years, an increasing role for noncoding small RNAs (miRNA) has been uncovered in carcinogenesis. These oligonucleotides can promote degradation and/or inhibit translation of key mRNAs. Recent studies have also highlighted a possible role for miRNAs in adult and pediatric brain tumors, including high- and low-grade gliomas, medulloblastoma, ependymoma, and neoplasms associated with neurofibromatosis type 1. Gliomas represent the most common category of primary intraparenchymal brain tumors, and, for example, manipulation of signaling pathways, through inhibition of PTEN transcription appears to be an important function of miRNA dysregulation through miR-21, miR-106b, and miR-26a. Moreover, altered miRNA expression in gliomas play roles in the regulation of common tumorigenic processes, including receptor tyrosine kinase signaling, angiogenesis, invasion, suppression of differentiation, cell cycle enhancement, and inhibition of apoptosis. Suppression of differentiation requires the downregulation of a number of miRNAs that are both enriched in the brain and required for terminal glial differentiation, including miR-219 and miR-338. Our evolving understanding about the biology of gliomas make them attractive for miRNA study, given that recent evidence suggests that epigenetic and subtle genetic changes may contribute to their pathogenesis. Identification of key miRNAs also provides a rationale for developing robust biomarkers and inhibitory RNA strategies for therapeutic purposes in glioma patients.

MicroRNA applications for prostate, ovarian and breast cancer in the era of precision medicine

The high degree of conservation in microRNA from Caenorhabditiselegans to humans has enabled relatively rapid implementation of findings in model systems to the clinic. The convergence of the capacity for genomic screening being implemented in the prevailing precision medicine initiative and the capabilities of microRNA to address these changes holds significant promise. However, prostate, ovarian and breast cancers are heterogeneous and face issues of evolving therapeutic resistance. The transforming growth factor-beta (TGFβ) signaling axis plays an important role in the progression of these cancers by regulating microRNAs. Reciprocally, microRNAs regulate TGFβ actions during cancer progression. One must consider the expression of miRNA in the tumor microenvironment a source of biomarkers of disease progression and a viable target for therapeutic targeting. The differential expression pattern of microRNAs in health and disease, therapeutic response and resistance has resulted in its application as robust biomarkers. With two microRNA mimetics in ongoing restorative clinical trials, the paradigm for future clinical studies rests on the current observational trials to validate microRNA markers of disease progression. Some of today's biomarkers can be translated to the next generation of microRNA-based therapies.

Therapy targeted to the metastatic niche is effective in a model of stage IV breast cancer

Treatment of stage IV metastatic breast cancer patients is limited to palliative options and represents an unmet clinical need. Here, we demonstrate that pharmacological inhibition of miRNA-10b - a master regulator of metastatic cell viability – leads to elimination of distant metastases in a mouse model of metastatic breast cancer. This was achieved using the miRNA-10b inhibitory nanodrug, MN-anti-miR10b, which consists of magnetic nanoparticles, conjugated to LNA-based miR-10b antagomirs. Intravenous injection of MN-anti-miR10b into mice bearing lung, bone, and brain metastases from breast cancer resulted in selective accumulation of the nanodrug in metastatic tumor cells. Weekly treatments of mice with MN-anti-miR-10b and low-dose doxorubicin resulted in complete regression of pre-existing distant metastases in 65% of the animals and a significant reduction in cancer mortality. These observations were supported by dramatic reduction in proliferation and increase in apoptosis in metastatic sites. On a molecular level, we observed a significant increase in the expression of HOXD10, which is a known target of miRNA-10b. These results represent first steps into the uncharted territory of therapy targeted to the metastatic niche.

EphB3-targeted regulation of miR-149 in the migration and invasion of human colonic carcinoma HCT116 and SW620 cells

microRNAs play key roles during various crucial cell processes such as proliferation, migration, invasion and apoptosis. Also, microRNAs have been shown to possess oncogenic and tumor-suppressive functions in human cancers. Here, we describe the regulation and function of miR-149 in colorectal cancer cell lines. miR-149 expression patterns were detected in human colorectal cell lines and tissue samples, and then focused on its role in regulation of cell growth, migration, invasion, and its target gene identification. Furthermore, the function of the target gene of miR-149 was analyzed in vitro and in vivo. miR-149 expression was downregulated in human colorectal cancer HCT116 and SW620 cell lines compared to the normal colon epithelial NCM460 cell line using quantitative real-time polymerase chain reaction methods. Further studies indicated that introduction of miR-149 was able to suppress cell migration and invasion. Then, EphB3 was identified as a direct target gene of miR-149 in colorectal cancer cells. Moreover, experiments in vitro showed that knockdown expression of EphB3 could suppress cell proliferation and invasion, and ectopic expression of EphB3 restored the phenotypes of CRC cell lines transfected with miR149. In addition, silencing of EphB3 significantly affected cycle progression distribution and increased apoptosis in CRC cell lines. Finally, in vivo results demonstrated that knockdown of EphB3 by siRNA inhibited tumor growth. In conclusion,the important role of miR-149 in colorectal cancer progression suggesting that miR-149 may serve as a therapeutic target for colorectal cancer treatment.

An Explorative Analysis for the Role of Serum miR-10b-3p Levels in Predicting Response to Sorafenib in Patients with Advanced Hepatocellular Carcinoma

The prognostic role of aberrant serum miRNA expression for predicting response to sorafenib treatment in advanced hepatocellular carcinoma (HCC) patients has not been well characterized. We aimed to identify specific serum miRNAs that are associated with positive radiologic responses or improved survival in sorafenib-treated HCC patients. miR-18a, miR-21, miR-139-5p, miR-221, miR-224, and miR-10b-3p, were selected for analysis. Serum samples from 24 patients with advanced stage HCC and 25 patients with liver cirrhosis (LC) were analyzed. All of the miRNAs except miR-21 were found to be upregulated in serum samples from HCC patients. None of the miRNAs assayed differed significantly in terms of expression between the responder and non-responder groups among HCC patients. However, miR-10b-3p levels were significantly higher in the subgroup of HCC patients with worse overall survival (fold change = 5.8, P = 0.008). Serum miRNA-10b-3p was upregulated in the presence of macrovascular invasion (MVI), and those with higher serum miRNA-10b-3p had significantly shorter survival during treatment (P = 0.042). Although no single serum miRNA was predictive of response to sorafenib treatment, analysis of serum miR-10b-3p levels may be valuable for diagnosis of HCC and prediction of survival of sorafenib-treated patients.

Up-regulation of mir-10b predicate advanced clinicopathological features and liver metastasis in colorectal cancer

Given the emerging role of microRNA in tumor disease progression, we investigated the association between miRNA 10b expression, liver metastasis, and clinicopathological of colorectal cancer (CRC). Two hundred and forty‐six pairs of samples (including CRC samples and normal adjacent tissues) from CRC patients were collected from May 2004 to May 2009. All samples verified to contain at least 80% tumor cells, and were immediately frozen in liquid nitrogen and stored at −80°C or fixed in 10% formalin for paraffin embedding. The expression of miRNA‐10b in CRC tissues was evaluated using a quantitative real‐time polymerase chain reaction RT‐PCR. Correlation between miR‐10b expression and poor clinicopathological of CRC patients were analyzed using Student's t‐tests and Chi‐square tests. A Kaplan–Meier survival curve was generated following a log‐rank test. miR‐10b expression was up‐regulated in CRC tissues (P < 0.0001) and in patients diagnosed as colorectal liver metastasis (CLM) at initial involvement or during follow‐up. When the Tumor Node Metastasis (TNM) stage was taken into consideration, the expression levels of miR‐10b were positively correlated with advanced TNM stages. In addition, the miR‐10b expression of patients diagnosed as CLM at initial involvement was significantly higher than those without liver metastasis (nCLM). Similarly, those patients developed with CLM during follow‐up (FCLM) was also markedly higher than those with nCLM. miR‐10b expression was also found correlated with advanced stage (P < 0.0001), lymph node metastasis (P = 0.025), venous infiltration (P = 0.007), poorer differentiation (P = 0.002), and served as an independent prognostic factor of poor overall survival (P < 0.0001). This study demonstrated the expression of miR‐10b had strong potential to serve as a noninvasive biomarker for CRC prognosis and predicting liver metastasis.

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.

Combining miR-10b-Targeted Nanotherapy with Low-Dose Doxorubicin Elicits Durable Regressions of Metastatic Breast Cancer

The therapeutic promise of microRNA (miRNA) in cancer has yet to be realized. In this study, we identified and therapeutically exploited a new role for miR-10b at the metastatic site, which links its overexpression to tumor cell viability and proliferation. In the protocol developed, we combined a miR-10b-inhibitory nanodrug with low-dose anthracycline to achieve complete durable regressions of metastatic disease in a murine model of metastatic breast cancer. Mechanistic investigations suggested a potent antiproliferative, proapoptotic effect of the nanodrug in the metastatic cells, potentiated by a cell-cycle arrest produced by administration of the low-dose anthracycline. miR-10b was overexpressed specifically in cells with high metastatic potential, suggesting a role for this miRNA as a metastasis-specific therapeutic target. Taken together, our results implied the existence of pathways that regulate the viability and proliferation of tumor cells only after they have acquired the ability to grow at distant metastatic sites. As illustrated by miR-10b targeting, such metastasis-dependent apoptotic pathways would offer attractive targets for further therapeutic exploration.

MicroRNAs in breast cancer: oncogene and tumor suppressors with clinical potential

MicroRNAs (miRs) are small single-stranded RNA molecules, which function as key negative regulators of post-transcriptional modulation in almost all biological processes. Abnormal expression of microRNAs has been observed in various types of cancer including breast cancer. Great efforts have been made to identify an association between microRNA expression profiles and breast cancer, and to understand the functional role and molecular mechanism of aberrant-expressed microRNAs. As research progressed, 'oncogenic microRNAs' and 'tumor suppressive microRNAs' became a focus of interest. The potential of candidate microRNAs from both intercellular (tissue) and extracellular (serum) sources for clinical diagnosis and prognosis was revealed, and treatments involving microRNA achieved some amazing curative effects in cancer disease models. In this review, advances from the most recent studies of microRNAs in one of the most common cancers, breast cancer, are highlighted, especially the functions of specifically selected microRNAs. We also assess the potential value of these microRNAs as diagnostic and prognostic markers, and discuss the possible development of microRNA-based therapies.

MiR-520d-5p directly targets TWIST1 and downregulates the metastamiR miR-10b

MicroRNAs are key players in most biological processes. Some microRNAs are involved in the genesis of tumors and are therefore termed oncomiRs, while others, termed metastamiRs, play a significant role in the formation of cancer metastases. Previously, we identified ten different cellular microRNAs that downregulate the expression of MICB, a ligand of the activating NK receptor NKG2D. Interestingly, several of the ten MICB-targeting microRNAs, such as miR-10b, are involved in tumor formation and metastasis. In this work, we identify a complex interplay between these different microRNAs. Specifically, we demonstrate that three of the MICB-targeting microRNAs: miR-20a, miR-17-5p and miR-93, also target the same site in the 3'UTR of TWIST1, a transcription factor implicated in cancer metastasis. Additionally, we show that miR-520d-5p targets a different site in the 3'UTR of TWIST1. We next show that the miR-520d-5p-mediated decrease of TWIST1 expression results in reduced expression of one of its targets, miR-10b, and in the restoration of E-Cadherin expression, which in turn results in reduced cellular motility and invasiveness. Finally, we show that miR-520d-5p leads to reduced proliferation of tumor cells, and that high levels of miR-520d-5p correlate with higher survival rates of cancer patients.

Small molecule compounds targeting miRNAs for cancer therapy

One of the most fascinating discoveries in molecular oncology has been that cancer represents a disease in which genetic alterations in protein-coding, but also in non-coding genes complement each other. MicroRNAs (miRNAs) are a type of non-coding RNA (ncRNA) transcripts that can regulate gene expression primarily by disrupting messenger RNA (mRNA) translation and/or stability, or alternatively by modulating the transcription of target mRNAs. For the last decade, miRNAs have shown to be pivotal characters of every single one of the cancer hallmarks. Profiling studies have proven the significance of identifying over-expressed miRNAs (oncomiRs) causative of the activation of oncogenic pathways that lead to malignancy. Due to their crucial role in cancer, it has become a challenge to develop efficient miRNA-inhibiting strategies such as antagomiRs, locked nucleic acids or antisense oligonucleotides. However, to this date, the accessible delivery agents and their pharmacokinetic/pharmacodynamic properties are not ideal. Thus there is an urgent, unmet need to develop miRNA-based inhibitory therapeutics. Herein we present a novel therapeutic strategy that is only at the tip of the iceberg: the use of small molecule inhibitors to target specific miRNAs (SMIRs). Furthermore we describe several high-throughput techniques to screen for SMIRs both in vitro and in silico. Finally we take you through the journey that has led to discovering the handful of SMIRs that have been validated to this date.

DNA methylation downregulated mir-10b acts as a tumor suppressor in gastric cancer

BACKGROUND

MicroRNAs act as tumor suppressors or oncogenes. The pathological roles of miRNAs in gastric tumorigenesis are largely unknown. Although miR-10b was identified as an miRNA deregulator expressed in gastric cancer (GC), there also exists some debate on whether miR-10b is acting as tumor suppressor or oncogene in GC.

METHODS

Quantitative RT-PCR was employed to investigate the level of miR-10b in GC tissues and matched adjacent normal tissues (n = 100). In vitro cell proliferation, apoptosis assays, cell migration, and invasion assays were performed to elucidate the biological effects of miR-10b. Because silencing of miRNA by promoter CpG island methylation may be an important mechanism in tumorigenesis, GC cells were treated with 5-aza-2'-deoxycytidine and trichostatin A, and expression changes of miR-10b were subsequently examined by quantitative RT-PCR. Furthermore, the methylation status of the CpG island upstream of miR-10b was analyzed by methylation-specific PCR in GC tissues (n = 29).

RESULTS

We showed here that miR-10b was significantly downregulated in GC cell lines and tissues as demonstrated by quantitative real-time PCR. Overexpression of miR-10b in MGC-803 and HGC-27 dramatically suppressed cell proliferation, migration, invasion, and induced apoptosis. Moreover, we demonstrated that T-cell lymphoma invasion and metastasis (Tiam1) was a target of miR-10b. Furthermore, 5-aza-2'-deoxycytidine and trichostain A increased miR-10b expression, and the methylation level was high in the CpG islands upstream of miR-10b gene.

CONCLUSIONS

Taken together, these findings suggest that miR-10b may function as a novel tumor suppressor and is partially silenced by DNA hypermethylation in GC.

A summary for molecular regulations of miRNAs in breast cancer

BACKGROUND

Breast cancer is the most frequently diagnosed cancer and the leading cause of cancer-related death among women worldwide. MicroRNAs (miRNAs) are naturally-occurring, non-coding small RNA molecules that can modulate protein coding-genes, which makes it contributing to nearly all the physiological and pathological processes. Progression of breast cancer and resistance to endocrine therapies have been attributed to the possibility of hormone-responsive miRNAs involved in the regulation of certain signaling pathways.

METHODOLOGY

This review introduces better understanding of miRNAs to provide promising advances for treatment. miRNAs have multiple targets, and they were found to regulate different signaling pathways; consequently it is important to characterize their mechanisms of action and their cellular targets in order to introduce miRNAs as novel and promising therapies.

RESULTS

This review summarizes the molecular mechanisms of miRNAs in TGF-beta signaling, apoptosis, metastasis, cell cycle, ER-signaling, and drug resistance.

CONCLUSION

Finally, miRNAs will be introduced as promising molecules to be used in the fight against breast cancer and its developed drug resistance.

Regulation of cancer metastasis by cell-free miRNAs

MicroRNAs (miRNAs) are integral molecules in the regulation of numerous physiological cellular processes that have emerged as critical players in cancer initiation and metastatic progression, both by promoting and suppressing metastasis. Recently, cell-free miRNAs shed from cancer cells into circulation have been reported in cancer patients, raising hope for development of novel biomarkers that can be routinely measured in easily accessible samples. In fact, establishing miRNA expression in the circulation likely has advantages over determination in primary tumor tissue, further augmenting the potential applications of miRNA detection in oncological practice. In addition, secretion of miRNAs impacting distant cell signaling or promoting the formation of a niche that sustains a distant tumor microenvironment allows for new treatment approaches to thwart cancer progression.

Up-regulation of microRNA-10b is associated with the development of breast cancer brain metastasis

Brain metastases from primary breast cancer are difficult to treat and associated with poor prognosis. Our understanding of the molecular basis for the development of such cancers is sparse. We hypothesized that the pro-metastatic microRNA-10b (miR-10b) plays a role in breast cancer brain metastasis. The study cohort comprised of twenty patients with breast cancer and brain metastasis as well as ten control patients (age, stage, and follow-up matched) with breast cancer without brain metastasis. All cases were microscopically reviewed to select tumor blocks with >50% tumor cells. RNA was extracted from formalin fixed paraffin embedded (FFPE) tumor tissue blocks. Expression of miR-10b was analyzed using qRT-PCR. The relevance of miR-10b expression was also tested using human breast cancer cell lines. An increased expression of miR-10b was noted in the primary breast cancer specimens of patients who subsequently developed brain metastasis, compared to those who did not. miR-10b also increased the invasive potential of breast cancer cells in vitro. Wilcoxon signed rank test revealed a statistically significant difference between the paired tumors from breast cancers and brain metastasis (p <0.001). Increased expression of miR-10b appears to be associated with breast cancer brain metastasis. These findings are clinically relevant since miR-10b could serve as a prognostic and/or therapeutic target for anti-metastatic therapy. Identifying molecular signatures of primary breast cancers which have a propensity for brain metastasis is critical for designing novel therapies to counter the development of brain metastasis in patients diagnosed with breast cancer.

miR149 functions as a tumor suppressor by controlling breast epithelial cell migration and invasion

Deregulated molecular signaling pathways are responsible for the altered adhesive, migratory, and invasive properties of cancer cells. The different breast cancer subtypes are characterized by the expression of distinct miRNAs, short non-coding RNAs that posttranscriptionally modulate the expression of entire gene networks. Profiling studies have revealed downregulation of miR149 in basal breast cancer. Here, we show that miR149 expression severely impairs cell spreading, migration, and invasion of basal-like breast cancer cells. We identify signaling molecules, including the small GTPases Rap1a and Rap1b, downstream of integrin receptors as miR149 targets, providing an explanation for the defective Src and Rac activation during cell adhesion and spreading upon miR149 expression. Suppression of cell spreading by miR149 could be rescued, at least in part, by expression of constitutively active Rac. Finally, we demonstrate that increased miR149 levels block lung colonization in vivo. On the basis of our findings, we propose that miR149 downregulation in basal breast cancer facilitates the metastatic dissemination of tumor cells by supporting aberrant Rac activation. Cancer Res; 74(18); 5256-65. ©2014 AACR.

MicroRNAs in the diagnosis and prognosis of breast cancer and their therapeutic potential (review)

MicroRNAs (miRNAs) are non-coding single-stranded RNAs in eukaryotes and are involved in the regulation of the post-transcriptional expression of specific genes. Studies have demonstrated that miRNAs play important roles in regulating diverse physiological events such as cell proliferation, differentiation and embryo development. In recent decades, considerable attention has been given to the relationship between miRNA and the pathology of cancers, particularly breast cancer. A large number of miRNAs have been shown to be involved in the pathophysiology of breast cancer. Studies have revealed that some miRNAs might regulate the oncogenesis and growth of breast cancer by acting on breast tumor-initiating cells or other downstream targets. Studies have also demonstrated that some miRNAs act as suppressors of metastasis or promoters of breast cancer. Additionally, certain miRNAs are involved in cancer tissue angiogenesis (one of the most important mechanisms of tumor growth and metastasis). Clinical evidence indicates that some miRNAs can be used as diagnostic and prognostic biomarkers for breast cancer due to their significantly increased or decreased expression in cancer tissue. Moreover, certain miRNAs may have therapeutic potential for targeting ER-α/HER, breast tumor-initiating cells and metastasis as well as multidrug resistance. In this review, we discuss the relationship between miRNAs and the pathogenesis of breast cancer as well as the progress of current research on the miRNA-specific diagnosis, prognosis and treatment of breast cancer.

MiR-182 is up-regulated and targeting Cebpa in hepatocellular carcinoma

MicroRNAs (miRNAs) are endogenous small non-coding RNAs that repress their targets at post transcriptional level. Existing studies have shown that miRNAs are important regulatory genes in hepatocellular carcinoma (HCC), as either tumor suppressors or oncogenes. MiR-122 is normally downregulated in HCC and regarded as a tumor suppressor. Recently miR-122 has been reported to be regulated by CEBPA, which is then involved in a novel pathway to influence proliferation of tumor cells. However it is unknown whether CEBPA is regulated by miRNAs in HCC. In this study, we find that miR-182 is upregulated in HCC model rat, and represses CEBPA in both rat and human. This further improves the current CEBPA/miR-122 pathway that controls the proliferation of tumor cells. These results suggest that miR-182 is a potential oncogene in HCC and could be used as a diagnostic marker and drug target of HCC.

Imperfect centered miRNA binding sites are common and can mediate repression of target mRNAs

Background

MicroRNAs (miRNAs) bind to mRNAs and target them for translational inhibition or transcriptional degradation. It is thought that most miRNA-mRNA interactions involve the seed region at the 5′ end of the miRNA. The importance of seed sites is supported by experimental evidence, although there is growing interest in interactions mediated by the central region of the miRNA, termed centered sites. To investigate the prevalence of these interactions, we apply a biotin pull-down method to determine the direct targets of ten human miRNAs, including four isomiRs that share centered sites, but not seeds, with their canonical partner miRNAs.

Results

We confirm that miRNAs and their isomiRs can interact with hundreds of mRNAs, and that imperfect centered sites are common mediators of miRNA-mRNA interactions. We experimentally demonstrate that these sites can repress mRNA activity, typically through translational repression, and are enriched in regions of the transcriptome bound by AGO. Finally, we show that the identification of imperfect centered sites is unlikely to be an artifact of our protocol caused by the biotinylation of the miRNA. However, the fact that there was a slight bias against seed sites in our protocol may have inflated the apparent prevalence of centered site-mediated interactions.

Conclusions

Our results suggest that centered site-mediated interactions are much more frequent than previously thought. This may explain the evolutionary conservation of the central region of miRNAs, and has significant implications for decoding miRNA-regulated genetic networks, and for predicting the functional effect of variants that do not alter protein sequence.

MiR-141 suppresses the migration and invasion of HCC cells by targeting Tiam1

Background

We have demonstrated that T lymphoma invasion and metastasis 1 (Tiam1) gene is associated with the poor prognosis of patients with hepatocellular carcinoma (HCC), and we used a computational approach to identify miR-141 as a Tiam1-targeting microRNA (miRNA). Here, we explored the function of miR-141 and the relationship between miR-141 and Tiam1 gene in HCC.

Methods

The miR-141 expression in HCC tissues and cell lines was detected and its roles in regulation of HCC cell proliferation, migration and invasion and target gene expression was investigated. Tiam1 was identified as a novel target of miR-141. Ethics statement: our study was approved by the Nanfang Hospital Medical Ethics Committee Ethics statement. Written informed consent was obtained before collection.

Results

Based on in situ hybridization (ISH) analysis, miR-141 was down-regulated in the same HCC samples. Kaplan-Meier analysis demonstrated that patients with low miR-141 expression had poorer overall survival rate than that of the patients with high miR-141 expression. Furthermore, multivariate Cox regression analysis indicated that miR-141 could serve as an independent prognostic factor in HCC. MiR-141 significantly inhibited in vitro cell proliferation, migration and invasion as proved by gain- and loss- of function studies, while the mRNA and protein levels of Tiam1 were reduced in cells over-expressing miR-141. Moreover, Tiam1 treatment antagonized this effect, while knockdown of Tiam1 by Tiam1 short hairpin RNA (shTiam1) induced inhibitory effects.

Conclusions

These findings indicated that miR-141 functions as a tumor suppressor and inhibits the migration and invasion of HCC cells by targeting Tiam1, which may provide novel prognostic and treatment strategies for HCC patients.

Therapeutic evaluation of microRNAs by molecular imaging

MicroRNAs (miRNAs) function as regulatory molecules of gene expression with multifaceted activities that exhibit direct or indirect oncogenic properties, which promote cell proliferation, differentiation, and the development of different types of cancers. Because of their extensive functional involvement in many cellular processes, under both normal and pathological conditions such as various cancers, this class of molecules holds particular interest for cancer research. MiRNAs possess the ability to act as tumor suppressors or oncogenes by regulating the expression of different apoptotic proteins, kinases, oncogenes, and other molecular mechanisms that can cause the onset of tumor development. In contrast to current cancer medicines, miRNA-based therapies function by subtle repression of gene expression on a large number of oncogenic factors, and therefore are anticipated to be highly efficacious. Given their unique mechanism of action, miRNAs are likely to yield a new class of targeted therapeutics for a variety of cancers. More than thousand miRNAs have been identified to date, and their molecular mechanisms and functions are well studied. Furthermore, they are established as compelling therapeutic targets in a variety of cellular complications. However, the notion of using them as therapeutic tool was proposed only recently, given that modern imaging methods are just beginning to be deployed for miRNA research. In this review, we present a summary of various molecular imaging methods, which are instrumental in revealing the therapeutic potential of miRNAs, especially in various cancers. Imaging methods have recently been developed for monitoring the expression levels of miRNAs and their target genes by fluorescence-, bioluminescence- and chemiluminescence-based imaging techniques. Mature miRNAs bind to the untranslated regions (UTRs) of the target mRNAs and regulate target genes expressions. This concept has been used for the development of fluorescent reporter-based imaging strategies to monitor the functional status of endogenous miRNAs, or the respective miRNAs transiently co-expressed in cells. Bioluminescence-based imaging strategies have been used to investigate various stages of miRNA processing and its involvement in different cellular processes. Similarly, chemiluminsecence methods were developed for in vitro miRNA imaging such as monitoring their therapeutic roles in various cancer cell lines.

Loss of miR-10a activates lpo and collaborates with activated Wnt signaling in inducing intestinal neoplasia in female mice

miRNAs are small regulatory RNAs that, due to their considerable potential to target a wide range of mRNAs, are implicated in essentially all biological process, including cancer. miR-10a is particularly interesting considering its conserved location in the Hox cluster of developmental regulators. A role for this microRNA has been described in developmental regulation as well as for various cancers. However, previous miR-10a studies are exclusively based on transient knockdowns of this miRNA and to extensively study miR-10a loss we have generated a miR-10a knock out mouse. Here we show that, in the Apc^min mouse model of intestinal neoplasia, female miR-10a deficient mice develop significantly more adenomas than miR-10^+/+ and male controls. We further found that Lpo is extensively upregulated in the intestinal epithelium of mice deprived of miR-10a. Using in vitro assays, we demonstrate that the primary miR-10a target KLF4 can upregulate transcription of Lpo, whereas siRNA knockdown of KLF4 reduces LPO levels in HCT-116 cells. Furthermore, Klf4 is upregulated in the intestines of miR-10a knockout mice. Lpo has previously been shown to have the capacity to oxidize estrogens into potent depurinating mutagens, creating an instable genomic environment that can cause initiation of cancer. Therefore, we postulate that Lpo upregulation in the intestinal epithelium of miR-10a deficient mice together with the predominant abundance of estrogens in female animals mainly accounts for the sex-related cancer phenotype we observed. This suggests that miR-10a could be used as a potent diagnostic marker for discovering groups of women that are at high risk of developing colorectal carcinoma, which today is one of the leading causes of cancer-related deaths.

Posttranscriptional regulation by microRNA molecules constitutes an important mechanism for gene regulation and numerous studies have demonstrated a correlation between deregulated microRNA levels and diseases, such as cancer. However, genetics studies linking individual microRNAs to the etiology of cancer remain scarce. Here, we provide causal evidence for the involvement of the conserved microRNA miR-10a in the development of intestinal adenomas in the face of activated Wnt signaling. Interestingly, we find that loss of miR-10a mediates an increase in intestinal adenomas in female mice only and delineate the pathway to involve aberrant upregulation of the miR-10a target Klf4 and subsequent transcriptional activation of the Lpo gene encoding the antibacterial protein Lactoperoxidase. Lpo, in turn, has previously been demonstrated to oxidize estrogens into DNA-damaging mutagens.

microRNA-10b enhances pancreatic cancer cell invasion by suppressing TIP30 expression and promoting EGF and TGF-β actions

Increased microRNA-10b (miR-10b) expression in the cancer cells in pancreatic ductal adenocarcinoma (PDAC) is a marker of disease aggressiveness. In the present study, we determined that plasma miR-10b levels are significantly increased in PDAC patients by comparison with normal controls. By gene profiling, we identified potential targets downregulated by miR-10b, including Tat-interacting protein 30 (TIP30). Immunoblotting and luciferase reporter assays confirmed that TIP30 was a direct miR-10b target. Downregulation of TIP30 by miR-10b or siRNA-mediated silencing of TIP30 enhanced epidermal growth factor (EGF)-dependent invasion. The actions of miR-10b were abrogated by expressing a modified TIP30 cDNA resistant to miR-10b. EGF-induced EGF receptor (EGFR) tyrosine phosphorylation and extracellular signal-regulated kinase phosphorylation were enhanced by miR-10b, and these effects were mimicked by TIP30 silencing. The actions of EGF in the presence of miR-10b were blocked by EGFR kinase inhibition with erlotinib and by dual inhibition of PI3K (phosphatidylinositol 3'-kinase) and MEK. Moreover, miR-10b, EGF and transforming growth factor-beta (TGF-β) combined to markedly increase cell invasion, and this effect was blocked by the combination of erlotinib and SB505124, a type I TGF-β receptor inhibitor. miR-10b also enhanced the stimulatory effects of EGF and TGF-β on cell migration and epithelial-mesenchymal transition (EMT) and decreased the expression of RAP2A, EPHB2, KLF4 and NF1. Moreover, miR-10b overexpression accelerated pancreatic cancer cell (PCC) proliferation and tumor growth in an orthotopic model. Thus, plasma miR-10b levels may serve as a diagnostic marker in PDAC, whereas intra-tumoral miR-10b promotes PCC proliferation and invasion by suppressing TIP30, which enhances EGFR signaling, facilitates EGF-TGF-β cross-talk and enhances the expression of EMT-promoting genes, whereas decreasing the expression of several metastasis-suppressing genes. Therefore, therapeutic targeting of miR-10b in PDAC may interrupt growth-promoting deleterious EGF-TGF-β interactions and antagonize the metastatic process at various levels.

microRNA-155 regulates cell proliferation and invasion by targeting FOXO3a in glioma

microRNAs (miRNAs) are short noncoding RNAs, which modulate the expression of numerous genes by targeting mRNAs. Numerous abnormal miRNA expression patterns are found in various human malignancies, and certain miRNAs act as oncogenes or tumor suppressors. microRNA-155 (miR‑155) may not only function as an oncogene but also as a tumor suppressor in various types of cancer cells, such as melanoma. Although miR-155 has been found to be upregulated in glioma, its role has not yet been eludicated in glioma tumorigenesis. Based on the prediction of the target genes of miR-155, we hypothesized that there is a significant association between miR-155 and FOXO3a, a negative regulator of Akt signaling. In the present study, we found that FOXO3a expression was significantly downregulated and miR-155 was upregulated in a panel of glioma cells and tissue specimens. Furthermore, we demonstrated that miR-155 induced cell proliferation by inhibiting apoptosis and promoted the migration and invasiveness of glioma cells, while miR-155 had no effect on the cell cycle as determined by gain-of-function and loss-of-function experiments. Moreover, we confirmed that miR-155 downregulated the expression of FOXO3a by directly targeting its 3'-UTR. These findings indicate that miR-155 may function as an oncogene by targeting FOXO3a in the development and progression of glioma.

The relevance of the TGF-β Paradox to EMT-MET programs

The role of transforming growth factor-β (TGF-β) during tumorigenesis is complex and paradoxical, reflecting its ability to function as a tumor suppressor in normal and early-stage cancers, and as a tumor promoter in their late-stage counterparts. The switch in TGF-β function is known as the "TGF-β Paradox," whose manifestations are intimately linked to the initiation of epithelial-mesenchymal transition (EMT) programs in developing and progressing carcinomas. Indeed, as carcinoma cells emerge from EMT programs stimulated by TGF-β, they readily display a variety of acquired phenotypes that provide a selective advantage to growing carcinomas, including (i) enhanced cell migration and invasion; (ii) heightened resistance to cytotoxic agents, targeted chemotherapeutic, and radiation treatments; and (iv) boosted expansion of cancer-initiating and stem-like cell populations that underlie tumor metastasis and disease recurrence. At present, the molecular, cellular, and microenvironmental mechanisms that enable post-EMT and metastatic carcinoma cells to hijack the oncogenic activities of TGF-β remain incompletely understood. Additionally, the molecular mechanisms that counter EMT programs and limit the aggressiveness of late-stage carcinomas, events that transpire via mesenchymal-epithelial transition (MET) reactions, also need to be further elucidated. Here we review recent advances that provide new insights into how TGF-β promotes EMT programs in late-stage carcinoma cells, as well as how these events are balanced by MET programs during the development and metastatic progression of human carcinomas.