Role of microRNA221 in regulating normal mammary epithelial hierarchy and breast cancer stem-like cells

NUF2 Promotes Breast Cancer Metastasis via Activating Wnt/β-Catenin Pathways

BACKGROUND

Breast cancer is the most common malignancy and the leading cause of cancer death among women. NDC80 kinetochore complex component (NUF2) is demonstrated to implicate the progression of human cancer. But the role of NUF2 in breast cancer progression is unclear. Here, we aimed to study the role and regulatory mechanisms of NUF2 in breast cancer metastasis.

METHODS

Immunohistochemistry was used to determine UNF2 expression in clinical samples. Transwell assas were used to determine the role of NUF2 in breast cancer migration and invasion. Animal model in vivo was used to determine the rold of NUF2 in breast cancer metastasis.

RESULTS

NUF2 was upregulated significantly in breast cancer tissues and cells. Worse prognosis was noted in patients with high NUF2 levels compared with that in patients with low NUF2 levels. NUF2 overexpression markedly enhanced, while NUF2 knockdown inhibited, breast cancer cell invasion and migration. Mechanistically, NUF2 was observed to upregulate Wnt/β-catenin signaling pathway activity. The promoting effect of NUF2 on cell migration and invasion were blocked by inhibition of the Wnt/β-catenin pathway.

CONCLUSIONS

We revealed that NUF2 promotes breast cancer progression via activating Wnt/β-catenin signaling, suggesting that NUF2 might be a new potential target for breast cancer treatment.

Gallic acid attenuates metastatic potential of human colorectal cancer cells through the miR-1247-3p-modulated integrin/FAK axis

Colorectal cancer (CRC) exhibits highly metastatic potential even in the early stages of tumor progression. Gallic acid (GA), a common phenolic compound in plants, is known to possess potent antioxidant and anticancer activities, thereby inducing cell death or cell cycle arrest. However, whether GA reduces the invasiveness of CRC cells without inducing cell death remains unclear. Herein, we aimed to investigate the antimetastatic activity of low-dose GA on CRC cells and determine its underlying mechanism. Cell viability and tumorigenicity were analyzed by MTS, cell adhesion, and colony formation assay. Invasiveness was demonstrated using migration and invasion assays. Changes in protein phosphorylation and expression were assessed by Western blot. The involvement of microRNAs was validated by microarray analysis and anti-miR antagonist. Our findings showed that lower dose of GA (≤100 μM) did not affect cell viability but reduced the capabilities of colony formation, cell adhesion, and invasiveness in CRC cells. Cellularly, GA downregulated the cellular level of integrin αV/β3, talin-1, and tensin and diminished the phosphorylated FAK, paxillin, Src, and AKT in DLD-1 cells. Microarray results revealed that GA increased miR-1247-3p expression, and pretreatment of anti-miR antagonist against miR-1247-3p restored the GA-reduced integrin αV/β3 and the GA-inhibited paxillin activation in DLD-1 cells. Consistently, the in vivo xenograft model showed that GA administration inhibited tumor growth and liver metastasis derived from DLD-1 cells. Collectively, our findings indicated that GA inhibited the metastatic capabilities of CRC cells, which may result from the suppression of integrin/FAK axis mediated by miR1247-3p.

The Intricate Interplay between Cancer Stem Cells and Oncogenic miRNAs in Breast Cancer Progression and Metastasis

Complex signaling interactions between cancer cells and their microenvironments drive the clonal selection of cancer cells. Opposing forces of antitumor and tumorigenic potential regulate the survival of the fittest clones, while key genetic and epigenetic alterations in healthy cells force them to transform, overcome cell senescence, and proliferate in an uncontrolled manner. Both clinical samples and cancer cell lines provide researchers with an insight into the complex structure and hierarchy of cancer. Intratumor heterogeneity allows for multiple cancer cell subpopulations to simultaneously coexist within tumors. One category of these cancer cell subpopulations is cancer stem cells (CSCs), which possess stem-like characteristics and are not easily detectable. In the case of breast cancer, which is the most prevalent cancer type among females, such subpopulations of cells have been isolated and characterized via specific stem cell markers. These stem-like cells, known as breast cancer stem cells (BCSCs), have been linked to major events during tumorigenesis including invasion, metastasis and patient relapse following conventional therapies. Complex signaling circuitries seem to regulate the stemness and phenotypic plasticity of BCSCs along with their differentiation, evasion of immunosurveillance, invasiveness and metastatic potential. Within these complex circuitries, new key players begin to arise, with one of them being a category of small non-coding RNAs, known as miRNAs. Here, we review the importance of oncogenic miRNAs in the regulation of CSCs during breast cancer formation, promotion and metastasis, in order to highlight their anticipated usage as diagnostic and prognostic tools in the context of patient stratification and precision medicine.

Epigenome-wide association study of short-term temperature fluctuations based on within-sibship analyses in Australian females

BACKGROUND

Temperature fluctuations can affect human health independent of the effect of mean temperature. However, no study has evaluated whether short-term temperature fluctuations could affect DNA methylation.

METHODS

Peripheral blood DNA methylation for 479 female siblings of 130 families were analysed. Gridded daily temperatures data were obtained, linked to each participant's home address, and used to calculate nine different metrics of short-term temperature fluctuations: temperature variabilities (TVs) within the day of blood draw and preceding one to seven days (TV 0-1 to TV 0-7), diurnal temperature range (DTR), and temperature change between neighbouring days (TCN). Within-sibship design was used to perform epigenome-wide association analyses, adjusting for daily mean temperatures, and other important covariates (e.g., smoking, alcohol use, cell-type proportions). Differentially methylated regions (DMRs) were further identified. Multiple-testing comparisons with a significant threshold of 0.01 for cytosine-guanine dinucleotides (CpGs) and 0.05 for DMRs were applied.

RESULTS

Among 479 participants (mean age ± SD, 56.4 ± 7.9 years), we identified significant changes in methylation levels in 14 CpGs and 70 DMRs associated with temperature fluctuations. Almost all identified CpGs were associated with exposure to temperature fluctuations within three days. Differentially methylated signals were mapped to 68 genes that were linked to human diseases such as cancer (e.g., colorectal carcinoma, breast carcinoma, and metastatic neoplasms) and mental disorder (e.g., schizophrenia, mental depression, and bipolar disorder). The top three most significantly enriched gene ontology terms were Response to bacterium (TV 0-3), followed by Hydrolase activity, acting on ester bonds (TCN), and Oxidoreductase activity (TV 0-3).

CONCLUSIONS

Short-term temperature fluctuations were associated with differentially methylated signals across the human genome, which provides evidence on the potential biological mechanisms underlying the health impact of temperature fluctuations. Future studies are needed to further clarify the roles of DNA methylation in diseases associated with temperature fluctuations.

Exosomal-microRNA transcriptome profiling of Parental and CSC-like MDA-MB-231 cells in response to cisplatin treatment

Triple negative breast cancer (TNBC) is the most aggressive breast cancer subtype with higher risk of metastasis and cancer reoccurrence. Cisplatin is one of the potential anticancer drugs for treating TNBC, where its effectiveness remains challenged by frequent occurrence of cisplatin resistance. Since acquirement of drug resistance often being associated with presence of cancer stem cells (CSCs), investigation has been conducted, suggesting CSC-like subpopulation to be more resistant to cisplatin than their parental counterpart. On the other hand, plethora evidences showed the transmission of exosomal-miRNAs are capable of promoting drug resistance in breast cancers. In this study, we aim to elucidate the differential expression of exosomal-microRNAs profile and reveal the potential target genes in correlation to cisplatin resistance associated with CSC-like subpopulation by using TNBC cell line (MDA-MB-231). Utilizing next generation sequencing and Nanostring techniques, cisplatin-induced dysregulation of exosomal-miRNAs were evaluated in maximal for CSC-like subpopulation as compared to parental cells. Intriguingly, more oncogenic exosomal-miRNAs profile was detected from treated CSC-like subpopulation, which may correlate to enhancement of drug resistance and maintenance of CSCs. In treated CSC-like subpopulation, unique clusters of exosomal-miRNAs namely miR-221-3p, miR-196a-5p, miR-17-5p and miR-126-3p were predicted to target on six genes (ATXN1, LATS1, GSK3β, ITGA6, JAG1 and MYC), aligned with previous finding which demonstrated dysregulation of these genes in treated CSC-like subpopulation. Our results highlight the potential correlation of exosomal-miRNAs and their target genes as well as novel perspectives of the corresponding pathways that may be essential to contribute to the attenuated cytotoxicity of cisplatin in CSC-like subpopulation.

miR-221/222 as biomarkers and targets for therapeutic intervention on cancer and other diseases: A systematic review

Among deregulated microRNAs (miRs) in human malignancies, miR-221 has been widely investigated for its oncogenic role and as a promising biomarker. Moreover, recent evidence suggests miR-221 as a fine-tuner of chronic liver injury and inflammation-related events. Available information also supports the potential of miR-221 silencing as promising therapeutic intervention. In this systematic review, we selected papers from the principal databases (PubMed, MedLine, Medscape, ASCO, ESMO) between January 2012 and December 2020, using the keywords "miR-221" and the specific keywords related to the most important hematologic and solid malignancies, and some non-malignant diseases, to define and characterize deregulated miR-221 as a valuable therapeutic target in the modern vision of molecular medicine. We found a major role of miR-221 in this view.

MicroRNAs in Molecular Classification and Pathogenesis of Breast Tumors

The current clinical practice of breast tumor classification relies on the routine immunohistochemistry-based expression analysis of hormone receptors, which is inadequate in addressing breast tumor heterogeneity and drug resistance. MicroRNA expression profiling in tumor tissue and in the circulation is an efficient alternative to intrinsic molecular subtyping that enables precise molecular classification of breast tumor variants, the prediction of tumor progression, risk stratification and also identifies critical regulators of the tumor microenvironment. This review integrates data from protein, gene and miRNA expression studies to elaborate on a unique miRNA-based 10-subtype taxonomy, which we propose as the current gold standard to allow appropriate classification and separation of breast cancer into a targetable strategy for therapy.

MicroRNA Regulation of Breast Cancer Stemness

Recent advances in our understanding of breast cancer have demonstrated that cancer stem-like cells (CSCs, also known as tumor-initiating cell (TICs)) are central for progression and recurrence. CSCs are a small subpopulation of cells present in breast tumors that contribute to growth, metastasis, therapy resistance, and recurrence, leading to poor clinical outcome. Data have shown that cancer cells can gain characteristics of CSCs, or stemness, through alterations in key signaling pathways. The dysregulation of miRNA expression and signaling have been well-documented in cancer, and recent studies have shown that miRNAs are associated with breast cancer initiation, progression, and recurrence through regulating CSC characteristics. More specifically, miRNAs directly target central signaling nodes within pathways that can drive the formation, maintenance, and even inhibition of the CSC population. This review aims to summarize these research findings specifically in the context of breast cancer. This review also discusses miRNAs as biomarkers and promising clinical therapeutics, and presents a comprehensive summary of currently validated targets involved in CSC-specific signaling pathways in breast cancer.

Epigenetics: New Insights into Mammary Gland Biology

The mammary gland undergoes important anatomical and physiological changes from embryogenesis through puberty, pregnancy, lactation and involution. These steps are under the control of a complex network of molecular factors, in which epigenetic mechanisms play a role that is increasingly well described. Recently, studies investigating epigenetic modifications and their impacts on gene expression in the mammary gland have been performed at different physiological stages and in different mammary cell types. This has led to the establishment of a role for epigenetic marks in milk component biosynthesis. This review aims to summarize the available knowledge regarding the involvement of the four main molecular mechanisms in epigenetics: DNA methylation, histone modifications, polycomb protein activity and non-coding RNA functions.

MicroRNAs, a Promising Target for Breast Cancer Stem Cells

Reactivation of the stem cell programme in breast cancer is significantly associated with persistent cancer progression and therapeutic failure. Breast cancer stem cells (BCSCs) are involved in the process of breast cancer initiation, metastasis and cancer relapse. Among the various important cues found in the formation and progression of BCSCs, microRNAs (miRNAs or miRs) play a pivotal role by regulating the expression of various tumour suppressor genes or oncogenes. Accordingly, there is evidence that miRNAs are associated with BCSC self-renewal, differentiation, invasion, metastasis and therapy resistance, and therefore cancer recurrence. miRNAs execute their roles by regulating the expression of stemness markers, activation of signalling pathways or their components and regulation of transcription networks in BCSCs. Therefore, a better understanding of the association between BCSCs and miRNAs has the potential to help design more effective and safer therapeutic solutions against breast cancer. Thus, an miRNA-based therapeutic strategy may open up new horizons for the treatment of breast cancer in the future. In view of this, we present the progress to date of miRNA research associated with stemness marker expression, signalling pathways and activation of transcription networks to regulate the self-renewal, differentiation and therapy resistance properties of BCSCs.

Long non-coding RNA SOX21-AS1 enhances the stemness of breast cancer cells via the Hippo pathway

Breast cancer stem cells (BCSCs) have high tumorigenicity and invasiveness, which contributes to recurrence and metastasis. The long non‐coding RNA SOX21‐AS1 has been previously reported to modulate the properties of breast cancer stem cells via targeting SOX2, although the underlying molecular mechanisms remain unclear. To investigate this issue, we first confirmed that the expression level of SOX21‐AS1 is increased in breast cancer tissues and cell lines (MCF‐7, MDA‐MB‐231, CSC‐MCF‐7, CSC‐MDA‐MB‐231), especially in BCSCs. We demonstrated that SOX21‐AS1 promotes the stemness of CSC‐MCF‐7 cells through western blot detection of stemness‐related proteins, as well as side population and sphere formation assays. Overexpression of SOX21‐AS1 enhanced the proliferation, migration and invasion of CSC‐MCF‐7 cells. We also observed that SOX21‐AS1 inhibited the Hippo pathway. SOX21‐AS1 enhanced the stemness, migration and invasion of CSC‐MCF‐7 cells by increasing the nuclear localization of YAP and decreasing the level of pYAP. Overall, we conclude that SOX21‐AS1 may promote the stemness viability, proliferation, migration and invasion of BCSCs by inhibiting the Hippo pathway. Our findings provide insights into potential biomarkers and prognostic measures for the treatment of breast cancer.

MicroRNA-221 and MicroRNA-222 in Common Human Cancers: Expression, Function, and Triggering of Tumor Progression as a Key Modulator

MicroRNAs (miRNAs) are a class of short (~22 nucleotides [nt]), single-stranded RNA oligonucleotides that are regulatory in nature and are often dysregulated in various diseases, including cancer. miRNAs can act as oncomiRs (miRNAs associated with cancer) or tumor suppressor miRNAs and have the potential to be a diagnostic, prognostic, noninvasive biomarker for these diseases. MicroRNA-221 (miR-221) and microRNA-222 (miR-222) are homologous miRNAs, located on the human chromosome Xp11.3, which factored significantly in impairment in the regulation of a wide range of cancers. In this review, we have highlighted the most consistently reported dysregulated miRNAs that trigger human tissues to express cancerous features and surveyed the role of those miRNAs in metastasis, apoptosis, angiogenesis, and tumor prognosis. Also, we applied the causes of drug resistance and the role of coordinated actions of these miRNAs to epigenetic changes and selected miRNAs as a potential type of cancer treatment.

G Protein-Coupled Receptor GPR87 Promotes the Expansion of PDA Stem Cells through Activating JAK2/STAT3

Cancer stem cells are the main reason for drug resistance and tumor relapse, and screening the targets for cancer stem cells is essential for tumor therapy. Here, we studied the role and regulatory mechanism of a G protein-coupled receptor named as G protein-coupled receptor 87 (GPR87) in the expansion of pancreatic ductal adenocarcinoma (PDA) stem cells. We found that GPR87 was an independent prognostic factor for PDA patients: patients with high GPR87 had a poor outcome. GPR87 significantly promoted the sphere formation ability, increased side population (SP) cell number, increased the expression of PDA stem cell markers, and increased the tumor initiation ability, suggesting that GPR87 promotes the expansion of PDA stem cells. Mechanism analysis suggested that signal transducer and activator of transcription 3 (STAT3) directly bound to the promoter of GPR87 to increase GPR87 expression; inversely, GPR87 also activated STAT3. Further analysis suggested that GPR87 activated Janus kinase 2 (JAK2), which can activate STAT3, inhibiting JAK2 activation in GPR87-overexpressing PDA cells, which significantly inhibited the expansion of PDA stem cells; these findings suggested that GPR87, JAK2, and STAT3 formed a positive feedback loop increasing PDA stem cell population. In PDA specimens, GPR87 expression is positively correlated with the phosphorylation level of STAT3 and JAK2, confirming GPR87 promoted PDA stem cell expansion through activating JAK2/STAT3. In summary, we found that GPR87, together with JAK2 and STAT3, formed a positive feedback loop to promote the expansion of PDA stem cells.

MECoRank: cancer driver genes discovery simultaneously evaluating the impact of SNVs and differential expression on transcriptional networks

Background

Although there are huge volumes of genomic data, how to decipher them and identify driver events is still a challenge. The current methods based on network typically use the relationship between genomic events and consequent changes in gene expression to nominate putative driver genes. But there may exist some relationships within the transcriptional network.

Methods

We developed MECoRank, a novel method that improves the recognition accuracy of driver genes. MECoRank is based on bipartite graph to propagates the scores via an iterative process. After iteration, we will obtain a ranked gene list for each patient sample. Then, we applied the Condorcet voting method to determine the most impactful drivers in a population.

Results

We applied MECoRank to three cancer datasets to reveal candidate driver genes which have a greater impact on gene expression. Experimental results show that our method not only can identify more driver genes that have been validated than other methods, but also can recognize some impactful novel genes which have been proved to be more important in literature.

Conclusions

We propose a novel approach named MECoRank to prioritize driver genes based on their impact on the expression in the molecular interaction network. This method not only assesses mutation’s effect on the transcriptional network, but also assesses the differential expression’s effect within the transcriptional network. And the results demonstrated that MECoRank has better performance than the other competing approaches in identifying driver genes.

Associating lncRNAs with small molecules via bilevel optimization reveals cancer-related lncRNAs

Long noncoding RNA (lncRNA) transcripts have emerging impacts in cancer studies, which suggests their potential as novel therapeutic agents. However, the molecular mechanism behind their treatment effects is still unclear. Here, we designed a computational model to Associate LncRNAs with Anti-Cancer Drugs (ALACD) based on a bilevel optimization model, which optimized the gene signature overlap in the upper level and imputed the missing lncRNA-gene association in the lower level. ALACD predicts genes coexpressed with lncRNAs mean while matching drug’s gene signatures. This model allows us to borrow the target gene information of small molecules to understand the mechanisms of action of lncRNAs and their roles in cancer. The ALACD model was systematically applied to the 10 cancer types in The Cancer Genome Atlas (TCGA) that had matched lncRNA and mRNA expression data. Cancer type-specific lncRNAs and associated drugs were identified. These lncRNAs show significantly different expression levels in cancer patients. Follow-up functional and molecular pathway analysis suggest the gene signatures bridging drugs and lncRNAs are closely related to cancer development. Importantly, patient survival information and evidence from the literature suggest that the lncRNAs and drug-lncRNA associations identified by the ALACD model can provide an alternative choice for cancer targeting treatment and potential cancer pognostic biomarkers. The ALACD model is freely available at https://github.com/wangyc82/ALACD-v1.

LncRNAs are RNA transcripts that are longer than 200 bp and do not encode proteins. Recent experimental studies have indicated the crucial role of lncRNAs in cancer. We proposed a computational model, ALACD, to understand a lncRNA’s molecular mechanism by associating it with a drug through the drug’s target genes. ALACD reveals lncRNAs, the associated anti-cancer drug, and the induced gene signatures that are involved in the regulation of cancer. Furthermore, these cancer-related lncRNAs are differentially expressed in cancer patients and closely associated with patient survival.

Dietary delphinidin inhibits human colorectal cancer metastasis associating with upregulation of miR-204-3p and suppression of the integrin/FAK axis

Delphinidin is a flavonoid belonging to dietary anthocyanidin family that has been reported to possess diverse anti-tumoral activities. However, the effects of delphinidin on colorectal cancer (CRC) cells and the underlying mechanisms are not fully understood. Thus, we aimed to investigate the anti-cancer activity of delphinidin in CRC cells and the underlying molecular mechanisms. The effects of delphinidin on the viability, metastatic characteristics, signaling, and microRNA (miR) profile of human CRC cell lines used were analyzed. In vivo metastasis was also evaluated using xenograft animal models. Our findings showed that delphinidin (<100 μM) inhibited the colony formation of DLD-1, SW480, and SW620 cells, but non-significantly affected cell viability. Delphinidin also suppressed the migratory ability and invasiveness of the tested CRC cell lines, downregulated integrin αV/β3 expression, inhibited focal adhesion kinase (FAK)/Src/paxillin signaling, and interfered with cytoskeletal construction. Analysis of the miR expression profile revealed a number of miRs, particularly miR-204-3p, that were significantly upregulated and downregulated by delphinidin. Abolishing the expression of one upregulated miR, miR-204-3p, with an antagomir restored delphinidin-mediated inhibition of cell migration and invasiveness in DLD-1 cells as well as the αV/β3-integrin/FAK/Src axis. Delphinidin also inhibited the lung metastasis of DLD-1 cells in the xenograft animal model. Collectively, these results indicate that the migration and invasion of CRC cells are inhibited by delphinidin, and the mechanism may involve the upregulation of miR-204-3p and consequent suppression of the αV/β3-integrin/FAK axis. These findings suggest that delphinidin exerts anti-metastatic effects in CRC cells by inhibiting integrin/FAK signaling and indicate that miR-204-3p may play an important role in CRC metastasis.

Myrothecine A modulates the proliferation of HCC cells and the maturation of dendritic cells through downregulating miR-221

Myrothecine A, characterized from the extracts of myrothecium roridum strain IFB-E012, isolated as endophytic fungi found in the traditional Chinese medicinal plant Artemisia annua. Here we investigated its roles on anti-tumor and immune regulation in vitro. Dendritic cells (DCs) are the most potent antigen presenting cells in immune responses. Recent studies have indicated that miRNAs are indispensable in regulating the development, differentiation, maturation and function of DC. MiR-221, acted as an oncogene, is an important regulator in cancer development by binding to 3' untranslated regions (3' UTR) of target mRNA. Here, we investigated whether myrothecine A could inhibit cell proliferation in hepatocellular carcinoma (HCC) cell line SMMC-7721 by regulating miR-221. The HCC cells were treated with myrothecine A at different concentration, and the cell growth ability was measured by MTT assay. Then we observed whether myrothecine A could affect the maturation of DC by regulating miR-221. The HCC cell line was co-cultured with immature DC from mice bone marrow, and the levels of CD86 and CD40 was detected by FCM. Our results showed that myrothecine A could rescue miR-221-induced cell proliferation and influence the protein level of p27 by inhibiting the expression of miR-221. In addition, myrothecine A could enhance the expression of CD86 and CD40 by reversing the function of miR-221. Therefore, myrothecine A may be acted as an anti-tumor drug to promote the maturation of DC in the microenvironment of hepatocellular carcinoma.

Overexpression of miR-489 derails mammary hierarchy structure and inhibits HER2/neu-induced tumorigenesis

Although it has been demonstrated that transformed progenitor cell population can contribute to tumor initiation, factors contributing to this malignant transformation are poorly known. Using in vitro and xenograft-based models, previous studies demonstrated that miR-489 acts as a tumor suppressor miRNA by targeting various oncogenic pathways. It has been demonstrated that miR-489 directly targets HER2 and inhibits the HER2 signaling pathway; however, its role in mammary gland development and HER2-induced tumor initiation hasn't been studied. To dissect the role of miR-489, we sorted different populations of mammary epithelial cells and determined that miR-489 was highly expressed in mammary stem cells. MMTV-miR-489 mice that overexpressed miR-489 in mammary epithelial cells were developed and these mice exhibited an inhibition of mammary gland development in early ages with a specific impact on highly proliferative cells. Double transgenic MMTV-Her2-miR489 mice were then generated to observe how miR-489 overexpression affects HER2-induced tumorigenesis. miR-489 overexpression delayed HER2-induced tumor initiation significantly. Moreover, miR-489 overexpression inhibited tumor growth and lung metastasis. miR-489 overexpression reduced mammary progenitor cell population significantly in preneoplastic mammary glands of MMTV-Her2 mice which showed a putative transformed population in HER2-induced tumorigenesis. The miR-489 overexpression reduced CD49fhiCD61hi populations in tumors that have stem-like properties, and miR-489 overexpression altered the HER2 signaling pathway in mammary tumors. Altogether, these data indicate that the inhibition of HER2-induced tumorigenesis by miR-489 overexpression was due to altering progenitor cell populations while decreasing tumor growth and metastasis via influencing tumor promoting genes DEK and SHP2.

MiRNA-221 from tissue may predict the prognosis of patients with osteosarcoma

This study was aimed to investigate the relationship between miR-221 expression and prognosis in patients with osteosarcoma.miR-221 expression in 69 osteosarcoma specimens and corresponding noncancer tissues were characterized by quantitative reverse transcription polymerase chain reaction. The associations of miR-221 expression with clinicopathologic factors and prognosis in patients with osteosarcoma were statistically analyzed.miR-221 expression in patients with osteosarcoma was significantly higher than in the corresponding noncancer tissues (P < .01). miR-221 overexpression was significantly associated with tumor stage, metastatic status, and response to chemotherapy pretreatment. Cox regression analysis revealed that miR-221expression, metastasis, and response to chemotherapy were independent prognostic indicators for osteosarcoma.miR-221 upregulation may predict clinical outcomes in patients with osteosarcoma.

Functional Role of Non-Coding RNAs during Epithelial-To-Mesenchymal Transition

Epithelial-to-mesenchymal transition (EMT) is a key biological process involved in a multitude of developmental and pathological events. It is characterized by the progressive loss of cell-to-cell contacts and actin cytoskeletal rearrangements, leading to filopodia formation and the progressive up-regulation of a mesenchymal gene expression pattern enabling cell migration. Epithelial-to-mesenchymal transition is already observed in early embryonic stages such as gastrulation, when the epiblast undergoes an EMT process and therefore leads to the formation of the third embryonic layer, the mesoderm. Epithelial-to-mesenchymal transition is pivotal in multiple embryonic processes, such as for example during cardiovascular system development, as valve primordia are formed and the cardiac jelly is progressively invaded by endocardium-derived mesenchyme or as the external cardiac cell layer is established, i.e., the epicardium and cells detached migrate into the embryonic myocardial to form the cardiac fibrous skeleton and the coronary vasculature. Strikingly, the most important biological event in which EMT is pivotal is cancer development and metastasis. Over the last years, understanding of the transcriptional regulatory networks involved in EMT has greatly advanced. Several transcriptional factors such as Snail, Slug, Twist, Zeb1 and Zeb2 have been reported to play fundamental roles in EMT, leading in most cases to transcriptional repression of cell⁻cell interacting proteins such as ZO-1 and cadherins and activation of cytoskeletal markers such as vimentin. In recent years, a fundamental role for non-coding RNAs, particularly microRNAs and more recently long non-coding RNAs, has been identified in normal tissue development and homeostasis as well as in several oncogenic processes. In this study, we will provide a state-of-the-art review of the functional roles of non-coding RNAs, particularly microRNAs, in epithelial-to-mesenchymal transition in both developmental and pathological EMT.

MicroRNA-221 may be involved in lipid metabolism in mammary epithelial cells

Milk lipids, important for infant growth and development, are produced and secreted by mammary gland under the regulation of steroid hormones, growth factors, and microRNAs (miRNAs). miR-221 has been identified in milk and adipocytes and it plays important roles in regulating normal mammary epithelial hierarchy and breast cancer stem cells; however, its roles in lipid metabolism in mammary epithelial cells (MECs), the cells of lipid synthesis and secretion, are as yet unknown. Through overexpression or inhibition of miR-221 expression, we found that it regulated lipid metabolism in MECs and was expressed differentially at various stages during murine mammary gland development. Inhibition of miR-221 expression increased lipid content in MECs through elevation of the lipid synthesis enzyme FASN, while overexpression of miR-221 reduced MEC lipid content. Moreover, the steroid hormones estradiol and progesterone decreased miR-221 expression with a subsequent increase in lipid formation in MECs. The expression of miR-221 was lower during lactation, which suggests that it may be involved in milk production. Therefore, miR-221 might be a useful target for influencing milk lipid production.

Dynamic and Modularized MicroRNA Regulation and Its Implication in Human Cancers

MicroRNA is responsible for the fine-tuning of fundamental cellular activities and human disease development. The altered availability of microRNAs, target mRNAs, and other types of endogenous RNAs competing for microRNA interactions reflects the dynamic and conditional property of microRNA-mediated gene regulation that remains under-investigated. Here we propose a new integrative method to study this dynamic process by considering both competing and cooperative mechanisms and identifying functional modules where different microRNAs co-regulate the same functional process. Specifically, a new pipeline was built based on a meta-Lasso regression model and the proof-of-concept study was performed using a large-scale genomic dataset from ~4,200 patients with 9 cancer types. In the analysis, 10,726 microRNA-mRNA interactions were identified to be associated with a specific stage and/or type of cancer, which demonstrated the dynamic and conditional miRNA regulation during cancer progression. On the other hands, we detected 4,134 regulatory modules that exhibit high fidelity of microRNA function through selective microRNA-mRNA binding and modulation. For example, miR-18a-3p, -320a, -193b-3p, and -92b-3p co-regulate the glycolysis/gluconeogenesis and focal adhesion in cancers of kidney, liver, lung, and uterus. Furthermore, several new insights into dynamic microRNA regulation in cancers have been discovered in this study.

MicroRNAs, a subpopulation of regulators, are involved in breast cancer progression through regulating breast cancer stem cells

Cancer stem cells (CSCs; also known as tumor-initiating cells) are essential effectors of tumor progression due to their self-renewal capacity, differentiation potential, tumorigenic ability and resistance to chemotherapy, all of which contribute to cancer relapse, metastasis and a poor prognosis. Breast cancer stem cells (BCSCs) have been identified to be involved in the processes of BC initiation, growth and recurrence. MicroRNAs (miRNAs) are a class of non-coding small RNAs of 19-23 nucleotides in length that regulate gene expression at the post-transcriptional level through various mechanisms, and serve critical roles in cancer progression. miRNAs have been demonstrated to elicit effects on BCSCs characteristics via the targeting of oncogenes or tumor suppressor genes. The present study focused on the effect of miRNAs on BCSC, including BCSC formation, self-renewal and differentiation, by which miRNAs may inhibit BCSC invasion and metastasis, modulate clonogenicity and tumorigenicity of BCSCs as well as regulate chemotherapy resistance to BC. Through an improved understanding of the association between BCSCs and miRNAs, a novel and safer therapeutic target for BC may be identified.

Spinocerebellar ataxia: miRNAs expose biological pathways underlying pervasive Purkinje cell degeneration

Recent work has demonstrated the importance of miRNAs in the pathogenesis of various brain disorders including the neurodegenerative disorder spinocerebellar ataxia (SCA). This review focuses on the role of miRNAs in the shared pathogenesis of the different SCA types. We examine the novel findings of a recent cell-type-specific RNA-sequencing study in mouse brain and discuss how the identification of Purkinje-cell-enriched miRNAs highlights biological pathways that expose the mechanisms behind pervasive Purkinje cell degeneration in SCA. These key pathways are likely to contain targets for therapeutic development and represent potential candidate genes for genetically unsolved SCAs.

Wound fluids affect miR-21, miR-155 and miR-221 expression in breast cancer cell lines, and this effect is partially abrogated by intraoperative radiation therapy treatment

Breast cancer is the most common malignant disease occurring in women. Conservative breast cancer surgery followed by radiation therapy is currently the standard treatment for this type of cancer. The majority of metastases occur within the scar, which initiated a series of studies. As a result, clinical trials aimed to assess whether localized radiotherapy, as intraoperative radiotherapy (IORT), may more effective in inhibiting the formation of local recurrence compared with the standard postoperative whole breast radiotherapy. The present study determined the role of postoperative wound fluids (WFs) from patients diagnosed with breast cancer subsequent to breast conserving surgery or breast conserving surgery followed by IORT on the expression of three microRNAs (miRNAs), consisting of miR-21, miR-155 and miR-221, in distinct breast cancer cell lines that represent the general subtypes of breast cancer. It was determined that the miRNAs responsible for breast cancer progression, induction of tumorigenesis and enrichment of the cancer stem cell phenotype, which is responsible for resistance to tumor therapy, were highly upregulated in the human epidermal growth factor receptor 2-positive breast cancer SK-BR-3 cell line following stimulation with WFs. It is worth emphasizing, that those changes were more significant in WFs collected from patients after surgery alone. The BT-549 cell line showed altered expression only of miR-155 following incubation with WFs. Notably, this change was not associated with IORT. Additionally, it was indicated that both WFs and RT-WF strongly downregulated the expression of miR-21, miR-155 and miR-221 in basal/epithelial and luminal subtypes of breast cancer. It was concluded that the present study contributes to an increased understanding of the role of surgical WFs and IORT treatment in the regulation of miRNA expression. This may enable the development of the current knowledge of breast cancer biology subsequent to IORT treatment and substantially to improve the therapy in the future.

miR-618 Inhibits Prostate Cancer Migration and Invasion by Targeting FOXP2

miRNAs play critical role in the development and progression of prostate cancer. Here we studied the role of miR-618 in prostate cancer migration and invasion. miR-618 was downregulated in metastatic androgen-independent prostate cancer (AIPC), patients with low miR-618 had poor outcome. Overexpression of miR-618 inhibited migration and invasion and induced mesenchymal to epithelial transition (MET). Conversely, knockdown of miR-618 promoted migration and invasion and induced epithelial to mesenchymal transition (EMT). FOXP2 was the direct target of miR-618, and promoted TGF-β expression, inhibition of TGF-β reversed the effect of miR-618 knockdown. We further analyzed the correlation between miR-618 expression and FOXP2 in human prostate cancer tissues, and found there was a negative correlation between miR-618 expression and FOXP2 levels. In conclusion, we found miR-618 inhibited prostate cancer migration and invasion by targeting FOXP2 and inhibiting TGF-β.

MicroRNA-140-5p inhibits invasion and angiogenesis through targeting VEGF-A in breast cancer

MicroRNAs (miRNAs) have been proven to be involved in cell metastasis and angiogenesis by interaction with the target mRNAs. Evidence has been confirmed that miR-140-5p is a tumor suppressor in human cancers such as breast cancer. However, the potential molecular mechanism of miR-140-5p in breast cancer invasion and angiogenesis is still poorly understood. According to our study, we reported that miR-140-5p inhibited the tumor invasion and angiogenesis of breast cancer cells both in vitro and in vivo by targeting VEGF-A. The mRNA amount of miR-140-5p was decreased in the breast cancer clinical samples and breast cancer with metastasis compared with the corresponding adjacent normal tissues and cancer without metastasis. MiR-140-5p mimics and a negative control were transfected into human MCF-7 and MDA-MB-231 cells. Transwell chambers were used to detect the invasive ability of the cells, and the angiogenic ability was assessed by tube-formation assay. The markers of invasion and angiogenesis, VEGF-A, CD31 and MMP-9, were detected by using immunohistochemistry and western blot analysis in vivo. VEGF-A was verified as a possible target gene of miR-140-5p, and corroborated by dual-luciferase reporter and ELISA. Taken together, the study elucidates the molecular mechanisms by which miR-140-5p inhibits breast cancer metastasis and angiogenesis, and provides a potent evidence for the development of a novel microRNA-targeting anticancer strategy for breast cancer patients.

Recent progress on the effects of microRNAs and natural products on tumor epithelial-mesenchymal transition

Epithelial–mesenchymal transition (EMT) is a biological process of phenotypic transition of epithelial cells that can promote physiological development as well as tissue healing and repair. In recent years, cancer researchers have noted that EMT is closely related to the occurrence and development of tumors. When tumor cells undergo EMT, they can develop enhanced migration and local tissue invasion abilities, which can lead to metastatic growth. Nevertheless, two researches in NATURE deny its necessity in specific tumors and that is discussed in this review. The degree of EMT and the detection of EMT-associated marker molecules can also be used to judge the risk of metastasis and to evaluate patients’ prognosis. MicroRNAs (miRNAs) are noncoding small RNAs, which can inhibit gene expression and protein translation through specific binding with the 3′ untranslated region of mRNA. In this review, we summarize the miRNAs that are reported to influence EMT through transcription factors such as ZEB, SNAIL, and TWIST, as well as some natural products that regulate EMT in tumors. Moreover, mutual inhibition occurs between some transcription factors and miRNAs, and these effects appear to occur in a complex regulatory network. Thus, understanding the role of miRNAs in EMT and tumor growth may lead to new treatments for malignancies. Natural products can also be combined with conventional chemotherapy to enhance curative effects.

MiR-200c Inhibits the Tumor Progression of Glioma via Targeting Moesin

We attempt to demonstrate the regulatory role of miR-200c in glioma progression and its mechanisms behind. Here, we show that miR-200c expression was significantly reduced in the glioma tissues compared to paratumor tissues, especially in malignant glioma. Exogenous overexpression of miR-200c inhibited the proliferation and invasion of glioma cells. In addition, the in vivo mouse xenograft model showed that miR-200c inhibited glioma growth and liver metastasis, which is mainly regulated by targeting moesin (MSN). We demonstrated that the expression of MSN in glioma specimens were negatively correlated with miR-200c expression, and MSN overexpression rescued the phenotype about cell proliferation and invasion induced by miR-200c. Moreover, knockdown of MSN was able to mimic the effects induced by miR-200c in glioma cells. These results indicate that miR-200c plays an important role in the regulation of glioma through targeting MSN.

MicroRNA-221 is involved in the regulation of osteoporosis through regulates RUNX2 protein expression and osteoblast differentiation

INTRODUCTION

MicroRNAs (miRNAs) has emerged as important factors in osteogenesis and chondrogenesis. This study aimed to determine whether miR-221 is involved in the regulation of osteoporosis and its underlying mechanism.

METHODS

Total RNA was extracted from fresh femoral neck trabecular bone from women undergoing hip replacement due to either osteoporotic fracture (OP group, n = 12) or osteoarthritis in the absence of osteoporosis (Control group, n = 12). Gene expression was quantified using TaqMan quantitative RT-PCR assays and protein production was determined by western blot analysis. The role of miR-221 in osteoblast differentiation was identified by gain or loss function experiment. MiRNA targets were identified using bioinformatics and luciferase reporter assay.

RESULTS

MiR-221 was down-regulated in the osteoporotic samples compared with non-osteoporotic controls, and decreased in a C2C12 cell model of osteogenic differentiation. Overexpression of miR-221 resulted in a decrease in the osteogenic potential, as indicated by the reduced expression levels of key osteoblast markers, including osteocalcin (OC), alkaline phosphatase (ALP) and collagen, type I, α 1 (COL1A1), whereas inhibition of miR-221 promoted the activity of OC, ALP and COL1A1. Then bioinformatic analysis identified potential target sites of the miR-221 located in the 3' untranslated regions of RUNX2. Western blot analysis demonstrated that miR-221 inhibited RUNX2 gene expression. Furthermore, dual-luciferase reporter assays confirmed that RUNX2 was a direct target of miR-221. Rescue experiments showed that overexpression of RUNX2 significantly attenuated the effect of miR-221 on osteoblast markers providing strong evidence that miR-221 mediated the osteoblast differentiation by targeting RUNX2.

CONCLUSIONS

Taken together, these data implied that miR-221 played an important part in osteoporosis through regulating RUNX2 expression and osteoblast differentiation.

miR-935 Promotes Liver Cancer Cell Proliferation and Migration by Targeting SOX7

Hepatocellular carcinoma (HCC) is the most common cancer in the world. MicroRNAs (miRNAs) are a type of small noncoding RNA that can regulate the expression of target genes under physiological and pathophysiological conditions. Aberrant expression of microRNA-935 (miR-935) has been reported in cancer studies. However, its expression and mechanism in HCC remain unclear. In our study, we found that miR-935 was upregulated in liver cancer tissues and cells. Overexpression of miR-935 in liver cells promoted cell proliferation, tumorigenesis, and cell cycle progression, whereas inhibition of miR-935 reduced cell proliferation, tumorigenicity, and cell cycle progression. These changes in the properties of HCC cells were associated with upregulation of two well-known cellular G₁/S transitional regulators: cyclin D1 and c-Myc. Additionally, we identified SOX7 as a direct target of miR-935. Overexpression of miR-935 inhibited SOX7 expression but promoted the levels of c-Myc and cyclin D1, which promotes cell proliferation and tumorigenesis; knockdown of miR-935 increased SOX7 level and inhibited c-Myc and cyclin D1 expression, whereas SOX7 silencing could promote cell proliferation, cell motility, and invasiveness in vitro. Our findings suggest that miR-935 represents a biomarker and a potential new target in HCC progression by suppressing SOX7 expression.

Therapeutic Efficacy of Cancer Stem Cell Vaccines in the Adjuvant Setting

Dendritic cell (DC)-based vaccine strategies aimed at targeting cancer stem-like cells (CSC) may be most efficacious if deployed in the adjuvant setting. In this study, we offer preclinical evidence that this is the case for a CSC-DC vaccine as tested in murine models of SCC7 squamous cell cancer and D5 melanoma. Vaccination of mice with an ALDH(high) SCC7 CSC-DC vaccine after surgical excision of established SCC7 tumors reduced local tumor relapse and prolonged host survival. This effect was augmented significantly by simultaneous administration of anti-PD-L1, an immune checkpoint inhibitor. In the minimal disease setting of D5 melanoma, treatment of mice with ALDH(high) CSC-DC vaccination inhibited primary tumor growth, reduced spontaneous lung metastases, and increased host survival. In this setting, CCR10 and its ligands were downregulated on ALDH(high) D5 CSCs and in lung tissues, respectively, after vaccination with ALDH(high) D5 CSC-DC. RNAi-mediated attenuation of CCR10 blocked tumor cell migration in vitro and metastasis in vivo T cells harvested from mice vaccinated with ALDH(high) D5 CSC-DC selectively killed ALDH(high) D5 CSCs, with additional evidence of humoral immunologic engagement and a reduction in ALDH(high) cells in residual tumors. Overall, our results offered a preclinical proof of concept for the use of ALDH(high) CSC-DC vaccines in the adjuvant setting to more effectively limit local tumor recurrence and spontaneous pulmonary metastasis, as compared with traditional DC vaccines, with increased host survival further accentuated by simultaneous PD-L1 blockade. Cancer Res; 76(16); 4661-72. ©2016 AACR.

Cross Talk between Cancer and Mesenchymal Stem Cells through Extracellular Vesicles Carrying Nucleic Acids

Extracellular vesicles (EVs) are considered to be a novel complex mechanism of cell communication within the tumor microenvironment. EVs may act as vehicles for transcription factors and nucleic acids inducing epigenetic changes in recipient cells. Since tumor EVs may be present in patient biological fluids, it is important to investigate their function and molecular mechanisms of action. It has been shown that tumor cells release EVs, which are capable of regulating cell apoptosis, proliferation, invasion, and epithelial-mesenchymal transition, as well as to suppress activity of immune cells, to enhance angiogenesis, and to prepare a favorable microenvironment for metastasis. On the other hand, EVs derived from stromal cells, such as mesenchymal stem cells (MSCs), may influence the phenotype of tumor cells through reciprocal cross talk greatly influenced by the transcription factors and nucleic acids they carry. In particular, non-coding RNAs (ncRNAs), including microRNAs and long ncRNAs, have recently been identified as the main candidates for the phenotypic changes induced in the recipient cells by EVs. ncRNAs, which are important regulators of mRNA and protein expression, can function either as tumor suppressors or as oncogenes, depending on their targets. Herein, we have attempted to revise actual evidence reported in the literature on the role of EVs in tumor biology with particular regard to the cross talk of ncRNAs between cancer cells and MSCs.

Mir-221/222 are promising targets for innovative anticancer therapy

INTRODUCTION

MicroRNAs (miRNAs) are key non-coding RNA post-transcriptional regulators of messenger RNAs (mRNAs), and are deeply dysregulated in human cancer. A rising body of evidence indicates that miRNAs represent valuable therapeutic targets. In this light, the cluster miR-221/222 are of particular relevance, given that they are strongly upregulated in a variety of solid and hematologic malignancies.

AREA COVERED

This review summarizes recent findings on the roles played by miR-221/222 in human cancer and their potential clinical value as promising targets for therapeutic studies.

EXPERT OPINION

The rising body of advanced preclinical evidence on the biological significance of miR-221/222 in a variety of malignancies indicates that they will play a crucial role in the future of innovative therapeutic strategies, both as validated biomarkers and targets.

miR-522 contributes to cell proliferation of hepatocellular carcinoma by targeting DKK1 and SFRP2

The morbidity and mortality of hepatocellular carcinoma (HCC) is very high, finding new therapeutic targets are critical for HCC treatment. miR-522 has been demonstrated to be upregulated in HCC tissues, but its role in HCC progression remains to be elucidated. In this report, we found miR-522 was upregulated in HCC cells and tissues, miR-522 overexpression promoted cell proliferation, colony formation, and cell cycle progression, whereas knockdown of miR-522 reduced these effects. We also analyzed the expression of several key cell cycle regulatory proteins and found overexpression of miR-522-inhibited cell cycle inhibitors p21 and p27 expression and enhanced cyclin D1 expression and the level of Rb phosphorylation, vice versa. These suggested miR-522-accelerated G1/S transition. DKK1 (dickkopf-1) and SFRP2 (secreted frizzled-related protein 2) were the targets of miR-522, their expression was inversely with miR-522 in HCC tissues. DKK1 and SFRP2 the antagonists of Wnt signaling, suggesting miR-522-promoted HCC progression through activating Wnt signaling. miR-522 might be a valuable target for HCC therapy.

miR-935 promotes gastric cancer cell proliferation by targeting SOX7

Gastric cancer is the most common cancer in the world, miRNAs have been demonstrated to play critical role in the development and progression of gastric cancer, such as miR-7, miR-217 and miR-335. Here, we found miR-935 was upregulated in gastric cancer tissues and cells. Overexpression of miR-935 promoted cell proliferation and tumorigenesis in vitro determined by MTT analysis, colony formation analysis, BrdU cell proliferation analysis and soft agar growth analysis, knockdown of miR-935 reduced these effects. Tumor suppressor sex-determining region Y-box 7 (SOX7) was the direct target of miR-935, overexpression of miR-935 inhibited SOX7 expression, but promoted the levels CCND1 and C-MYC which promotes cell proliferation and tumorigenesis, knockdown of miR-935 increased SOX7 level, and inhibited CCND1 and C-MYC expression. Synchronous knockdown of miR-935 and SOX7 promoted cell proliferation and tumorigenesis in vitro, confirming miR-935 regulated gastric cancer cell proliferation by inhibiting SOX7. In summary, we found miR-935 contributed to cell proliferation of gastric cancer through targeting SOX7.

C14orf166 overexpression correlates with tumor progression and poor prognosis of breast cancer

BACKGROUND

Chromosome 14 open reading frame 166 (C14orf166) is upregulated in various tumors, but its role in breast cancer has not been reported.

METHODS

Quantitative real-time PCR and western blot were used to determine C14orf166 expression in normal breast epithelial cells (NBEC), breast cancer cells, and four matched pairs of breast cancer tissues and adjacent noncancerous tissues. Using immunohistochemistry, we determined C14orf166 expression in paraffin-embedded tissues from 121 breast cancer patients. Statistical analyses were performed to examine the associations among C14or166 expression, clinicopathological parameters and prognosis outcome of breast cancer. MTT and colony formation assay were used to determine the effect of C14orf166 on cell proliferation by overexpression or knockdown of C14orf166 level.

RESULTS

C14orf166 was upregulated in breast cancer cell lines and tissues compared with the normal cells and adjacent normal breast tissues, high C14orf166 expression was positively with advancing clinical stage. The correlation analysis between C14orf166 expression and clinicopathological characteristics suggested C14orf166 expression was significantly correlated with clinical stages, T classification, N classification and PR expression, Kaplan-Meier curves with log rank tests showed patients with low C14orf166 expression had better survival, Cox-regression analysis suggested C14orf166 was an unfavorable prognostic factor for breast cancer patients. C14orf166 overexpression promoted breast cancer cell proliferation, whereas knockdown of C14orf166 inhibited this effect. Further analysis found C14orf166 overexpression inhibited cell cycle inhibitors P21 and P27 expression, and increased the levels of Cyclin D1 and phosphorylation of Rb, suggesting C14orf166 contributed to cell proliferation by regulating G1/S transition.

CONCLUSION

Our findings suggested C14orf166 could be a novel prognostic biomarker of breast cancer, it also contributes to cell proliferation by regulating G1/S transition.

The interplay between microRNAs and Twist1 transcription factor: a systematic review

Twist1 (also known as Twist) is a transcription factor that belongs to the family of basic helix-loop-helix (bHLH) proteins. It functions as a negative regulator of epithelial gene expression and a positive regulator of mesenchymal gene expression, thereby leading to induction of the epithelial mesenchymal transition (EMT), a process in which epithelial cells acquire the motile and migratory characteristics of mesenchymal cells. In addition to regulating the expression of protein-coding genes, Twist1 regulates the expression of microRNAs (miRNAs), adding a regulatory layer to EMT induction. Interestingly, the mRNA of Twist1 represents a downstream target of miRNAs, indicating an intricate network between miRNAs and Twist1. This network was shown to play multiple roles in cancer cell migration, invasion, and metastasis. The network can induce angiogenesis, protect cells from oncogene-induced apoptosis and senescence, enhance cancer cell resistance to conventional therapies, and increase cancer stem cell (CSC) populations. Recently, miRNAs have attracted considerable attention as potential promising tools in cancer therapies. Thus, this systematic review was conducted to clarify the reciprocal link between Twist1 and miRNAs in order to provide potential candidate miRNAs for diagnostic and therapeutic approaches in cancer treatment.

Overexpression of MicroRNA-221 is associated with poor prognosis in non-small cell lung cancer patients

The abnormal expression of microRNA-221 was detected in several cancers and some studies had indicated that microRNA-221 was associated with cancer prognosis. This study was aimed to evaluate the prognostic significance of microRNA-221 in non-small cell lung cancer (NSCLC). Quantitative real-time polymerase chain reaction (qRT-PCR) was used for detecting the relative expression levels of microRNA-221 in the pathological tissues and corresponding normal tissues of 104 NSCLC patients. The relationship between the expression levels and the clinical features was estimated by Chi-square method and the overall survival of patients at different expression levels was demonstrated by Kaplan-Meier method. Cox regression analysis was used to evaluate the prognostic significance of microRNA-221. The relative expression levels of microRNA-221 in the pathological tissues were remarkably higher than that in the corresponding normal tissues (1.71 vs 1.07, P = 0.000). The expression level was associated with lymph node metastasis (P = 0.001). The results of Kaplan-Meier method indicated that patients with high expression level of microRNA-221 had shorter overall survival time than those with low expression level (36.8 vs 45.2 months, P = 0.001). Moreover, Cox regression analysis suggested that microRNA-221 was a useful independent biomarker for NSCLC prognosis (HR = 1.873, 95 % CI = 1.267-2.768, P = 0.002). The aberrant expression of microRNA-221 is associated with NSCLC progression and it might be a potential biomarker for NSCLC prognosis.

MiR-221 promotes stemness of breast cancer cells by targeting DNMT3b

Cancer stem cells (CSCs) are a small part of the heterogeneous tumor cell population possessing self-renewal and multilineage differentiation potential as well as a great ability to sustain tumorigenesis. The molecular pathways underlying CSC phenotype are not yet well characterized. MicroRNAs (miRs) are small noncoding RNAs that play a powerful role in biological processes. Early studies have linked miRs to the control of self-renewal and differentiation in normal and cancer stem cells. We aimed to study the functional role of miRs in human breast cancer stem cells (BCSCs), also named mammospheres. We found that miR-221 was upregulated in BCSCs compared to their differentiated counterpart. Similarly, mammospheres from T47D cells had an increased level of miR-221 compared to differentiated cells. Transfection of miR-221 in T47D cells increased the number of mammospheres and the expression of stem cell markers. Among miR-221's targets, we identified DNMT3b. Furthermore, in BCSCs we found that DNMT3b repressed the expression of various stemness genes, such as Nanog and Oct 3/4, acting on the methylation of their promoters, partially reverting the effect of miR-221 on stemness. We hypothesize that miR-221 contributes to breast cancer tumorigenicity by regulating stemness, at least in part through the control of DNMT3b expression.

miR-411 contributes the cell proliferation of lung cancer by targeting FOXO1

Lung cancer is the leading cause of cancer deaths worldwide; the study of microRNAs gives new hope for lung cancer treatment. miR-411 has been demonstrated to be an independent prognostic factor for lung adenocarcinoma, but the role and regulatory mechanism are largely unknown. In the present study, we found miR-411 was overexpressed in the lung cancer cells; overexpression of miR-411 promoted anchorage-dependent and anchorage-independent growths of lung cancer, while miR-411 knockdown reduced this effect. Further study showed forkhead box O1 (FOXO1) was a target of miR-411. Overexpression of miR-411 suppressed the expression of FOXO1; the effect of suppression was abrogated when the mutation occurred in the 3'UTR of FOXO1. Knockdown of FOXO1 in cells which miR-411 was inhibited recapitulated the phenotype of miR-411 overexpression. Taken together, our study revealed miR-411 promoted cell proliferation of lung cancer by targeting tumor suppressor gene FOXO1 and miR-411 might be a potential target for lung cancer therapy.

miR-221 Promotes Epithelial-Mesenchymal Transition through Targeting PTEN and Forms a Positive Feedback Loop with β-catenin/c-Jun Signaling Pathway in Extra-Hepatic Cholangiocarcinoma

Extrahepatic cholangiocarcinoma (EHCC) is a refractory malignancy with poor prognosis due to its early invasion, metastasis and recurrence after operation. Therefore, understanding the mechanisms of invasion and metastasis is the key to the development of new and effective therapeutic strategies for EHCC. In the present study we demonstrated that miR-221 promoted EHCC invasion and metastasis through targeting PTEN and formed a positive feedback loop with β-catenin/c-Jun signaling pathway. We found miR-221 was upregulated in EHCC specimens and CC cell lines. Moreover, miR-221 was found strongly associated with the metastasis and prognosis of EHCC patients. The expression of PTEN was downregulated in EHCC patients and CC cell lines, and was further demonstrated as one of the downstream targets of miR-221. In addition, our data indicated that β-catenin activated miR-221 through c-jun, while miR-221 enhanced β-catenin signaling induced-epithelial-mesenchymal transition (EMT) by targeting PTEN, hence forming a positive feedback loop in EHCC cell lines. In conclusion, our results suggested that miR-221 promotes EMT through targeting PTEN and forms a positive feedback loop with β-catenin/c-Jun signaling pathway in EHCC.

The roles of ncRNAs and histone-modifiers in regulating breast cancer stem cells

Cancer stem cells (CSCs), a subpopulation of cancer cells with ability of initiating tumorigenesis, exist in many kinds of tumors including breast cancer. Cancer stem cells contribute to treatment resistance and relapse. Conventional treatments only kill differentiated cancer cells, but spare CSCs. Combining conventional treatments with therapeutic drugs targeting to CSCs will eradicate cancer cells more efficiently. Studying the molecular mechanisms of CSCs regulation is essential for developing new therapeutic strategies. Growing evidences showed CSCs are regulated by non-coding RNA (ncRNA) including microRNAs and long non-coding RNAs (lncRNAs), and histone-modifiers, such as let-7, miR-93, miR-100, HOTAIR, Bmi-1 and EZH2. Herein we review the roles of microRNAs, lncRNAs and histone-modifiers especially Polycomb family proteins in regulating breast cancer stem cells (BCSCs).

Exploring miRNA-Associated Signatures with Diagnostic Relevance in Glioblastoma Multiforme and Breast Cancer Patients

The growing attention that non-coding RNAs have attracted in the field of cancer research in recent years is undeniable. Whether investigated as prospective therapeutic targets or prognostic indicators or diagnostic biomarkers, the clinical relevance of these molecules is starting to emerge. In addition, identification of non-coding RNAs in a plethora of body fluids has further positioned these molecules as attractive non-invasive biomarkers. This review will first provide an overview of the synthetic cascade that leads to the production of the small non-coding RNAs microRNAs (miRNAs) and presents their strengths as biomarkers of disease. Our interest will next be directed at exploring the diagnostic utility of miRNAs in two types of cancer: the brain tumor glioblastoma multiforme (GBM) and breast cancer. Finally, we will discuss additional clinical implications associated with miRNA detection as well as introduce other non-coding RNAs that have generated recent interest in the cancer research community.