miR-493 induction during carcinogenesis blocks metastatic settlement of colon cancer cells in liver. EMBO J. 2012;31:1752-1763. [PMID: 22373578 DOI: 10.1038/emboj.2012.25]

Proteomic profiling and network biology of colorectal cancer liver metastasis

INTRODUCTION

Tissue-based proteomic studies of colorectal cancer (CRC) metastasis have delivered fragmented results, with very few therapeutic targets and prognostic biomarkers moving beyond the discovery phase. This situation is likely due to the difficulties in obtaining and analyzing large numbers of patient-derived metastatic samples, the own heterogeneity of CRC, and technical limitations in proteomics discovery. As an alternative, metastatic CRC cell lines provide a flexible framework to investigate the underlying mechanisms and network biology of metastasis for target discovery.

AREAS COVERED

In this perspective, we comment on different in-depth proteomic studies of metastatic versus non-metastatic CRC cell lines. Identified metastasis-related proteins are introduced and discussed according to the spatial location in different cellular fractions, with special emphasis on membrane/adhesion proteins, secreted proteins, and nuclear factors, including miRNAs associated with liver metastasis. Moreover, we analyze the biological significance and potential therapeutic applications of the identified liver metastasis-related proteins.

EXPERT OPINION

The combination of protein discovery and functional analysis is the only way to accelerate the progress to clinical translation of the proteomic-derived findings in a relatively fast pace. Patient-derived organoids represent a promising alternative to patient tissues and cell lines, but further optimizations are still required for achieving solid and reproducible results.

MicroRNAs Influence the Migratory Ability of Human Umbilical Vein Endothelial Cells

To identify miRNAs that are involved in cell migration in human umbilical vein endothelial cells (HUVECs), we employed RNA sequencing under high glucose incubation and text mining within the databases miRWalk and TargetScanHuman using 83 genes that regulate HUVECs migration. From both databases, 307 predicted miRNAs were retrieved. Differentially expressed miRNAs were determined by exposing HUVECs to high glucose stimulation, which significantly inhibited the migratory ability of HUVECs as compared to cells cultured in normal glucose. A total of 35 miRNAs were found as differently expressed miRNAs in miRNA sequencing, and 4 miRNAs, namely miR-21-3p, miR-107, miR-143-3p, and miR-106b-5p, were identified as overlapping hits. These were subjected to hub gene analysis and pathway analysis using the Kyoto Encyclopedia of Genes and Genomes (KEGG), identifing 71 pathways which were influenced by all four miRNAs. The influence of all four miRNAs on HUVEC migration was phenomorphologically confirmed. miR21 and miR107 promoted migration in HUVECs while miR106b and miR143 inhibited migration. Pathway analysis also revealed eight shared pathways between the four miRNAs. Protein–protein interaction (PPI) network analysis was then performed to predict the functionality of interacting genes or proteins. This revealed six hub genes which could firstly be predicted to be related to HUVEC migration.

MicroRNA as an Important Target for Anticancer Drug Development

Cancer has become the second greatest cause of death worldwide. Although there are several different classes of anticancer drugs that are available in clinic, some tough issues like side-effects and low efficacy still need to dissolve. Therefore, there remains an urgent need to discover and develop more effective anticancer drugs. MicroRNAs (miRNAs) are a class of small endogenous non-coding RNAs that regulate gene expression by inhibiting mRNA translation or reducing the stability of mRNA. An abnormal miRNA expression profile was found to exist widely in cancer cell, which induces limitless replicative potential and evading apoptosis. MiRNAs function as oncogenes (oncomiRs) or tumor suppressors during tumor development and progression. It was shown that regulation of specific miRNA alterations using miRNA mimics or antagomirs can normalize the gene regulatory network and signaling pathways, and reverse the phenotypes in cancer cells. The miRNA hence provides an attractive target for anticancer drug development. In this review, we will summarize the latest publications on the role of miRNA in anticancer therapeutics and briefly describe the relationship between abnormal miRNAs and tumorigenesis. The potential of miRNA-based therapeutics for anticancer treatment has been critically discussed. And the current strategies in designing miRNA targeting therapeutics are described in detail. Finally, the current challenges and future perspectives of miRNA-based therapy are conferred.

microRNAs and Corresponding Targets Involved in Metastasis of Colorectal Cancer in Preclinical In Vivo Models

The high death toll of colorectal cancer patients is due to metastatic disease which is difficult to treat. The liver is the preferred site of metastasis, followed by the lungs and peritoneum. In order to identify new targets and new modalities of intervention we surveyed the literature for microRNAs (miRs) which modulate metastasis of colorectal cancer in preclinical in vivo models. We identified 12 up-regulated and 19 down-regulated miRs corresponding to the latter criterium. The vast majority (n=16) of identified miRs are involved in modulation of epithelial-mesenchymal transition (EMT). Other categories of metastasis-related miRs exhibit tumor- and metastasis-suppressing functions, modulation of signaling pathways, transmembrane receptors and a class of miRs, which interfere with targets which do not fit into these categories. Finally, we discuss the principles of miR inhibition and reconstitution of function, prospective clinical evaluation of with miR-related agents in the context of clinical evaluation in metastasis relevant settings.

miR-493 by regulating of c-Jun targets Wnt5a/PD-L1-inducing esophageal cancer cell development

BACKGROUND

Esophageal cancer is one of the most common cancers across the globe; the 5-year survival of esophageal cancer patients is still low. MicroRNA (miRNA) dysregulation has been implicated in cancer development, and the miRNAs play a pivotal role in esophageal cancer pathogenesis. It is urgently needed to find out how miRNA dysregulation was involved in esophageal cancer (EC) development.

METHODS

Through experiments in vivo and in vitro, we explored potential signaling pathways, miR-493/Wnt5A/c-JUN loop, in EC. Their mechanistic roles in EC cell proliferation, migration, and invasion were investigated through multiple validation steps in EC9706 and TE13 cell lines and EC specimens.

RESULTS

Overexpression of miR-493 attenuates esophageal cancer cell proliferation, migration, and invasion in vivo and in vitro. Moreover, miR-493 downregulation is an unfavorable factor in EC and negatively correlated with Wnt5A. The existence of miR-493 is also an important attribute of metabolism. Based on mechanism analyses, we show that miR-493 inhibits the activity of c-JUN and p-PI3K/p-AKT with enhanced p21 and directly regulates Wnt5A expression and function, whereas c-JUN binds the promoter region of miR-493 and suppressed the expression of miR-493, forming a negative feedback loop.

CONCLUSIONS

The miR-493/Wnt5A/c-JUN loop is a molecular feedback loop that refers to the development of esophageal cancer cells and a potential target for the treatment of esophageal cancer.

Extracellular vesicles carrying miR-193a derived from mesenchymal stem cells impede cell proliferation, migration and invasion of colon cancer by downregulating FAK

MicroRNA (miR) deregulation is frequently seen in colon cancer. In this study, we sought to investigate biological effects of miR-193a on colon cancer and its underlying mechanism. Microarray analysis was conducted to obtain the differentially expressed miRs and their target genes in colon cancer. Bone-marrow derived mesenchymal stem cells (MSCs) and extracellular vesicles (EVs) were obtained. The functional roles of miR-193a and FAK in colon cancer were determined using loss- and gain-function experiments. The cell proliferation, and migration and invasion were evaluated by CCK-8 and Transwell assay respectively. Dual-luciferase reporter assay was performed to confirm the targeting relationship between miR-193a and FAK. Furthermore, in vivo experiment was conducted to test the roles of EV miR-193a in colon cancer growth, followed by determination of PCNA, MMP-2, and MMP-9 protein expression using Western blot analysis. MiR-193a was downregulated, whereas FAK was upregulated in colon cancer. MiR-193a upregulation or FAK downregulation inhibited proliferation, migration and invasion of colon cancer cells. miR-193a could downregulate FAK. Upregulation of EV miR-193a was observed to impede proliferation, migration and invasion of colon cancer cells in vitro and in vivo, accompanied by decreased PCNA, MMP-2, and MMP-9 expression. In summary, EV miR-193a derived from MSCs impeded colon cancer progression by targeting FAK, thus suggesting a new potential strategy for colon cancer treatment.

MicroRNA-493-5p-mediated repression of the MYCN oncogene inhibits hepatic cancer cell growth and invasion

Primary hepatic tumors mainly include hepatocellular carcinoma (HCC), which is one of the most frequent causes of cancer‐related deaths worldwide. Thus far, HCC prognosis has remained extremely poor given the lack of effective treatments. Numerous studies have described the roles played by microRNAs (miRNAs) in cancer progression and the potential of these small noncoding RNAs for diagnostic or therapeutic applications. The current consensus supports the idea that direct repression of a wide range of oncogenes by a single key miRNA could critically affect the malignant properties of cancer cells in a synergistic manner. In this study, we aimed to investigate the oncogenes controlled by miR‐493‐5p, a major tumor suppressor miRNA that inactivates miR‐483‐3p oncomir in hepatic cancer cells. Using global gene expression analysis, we highlighted a set of candidate genes potentially regulated by miR‐493‐5p. In particular, the canonical MYCN protooncogene (MYCN) appeared to be an attractive target of miR‐493‐5p given its significant inhibition through 3′‐UTR targeting in miR‐493‐5p‐rescued HCC cells. We showed that MYCN was overexpressed in liver cancer cell lines and clinical samples from HCC patients. Notably, MYCN expression levels were inversely correlated with miR‐493‐5p in tumor tissues. We confirmed that MYCN knockdown mimicked the anticancer effect of miR‐493‐5p by inhibiting HCC cell growth and invasion, whereas MYCN rescue hindered miR‐493‐5p activity. In summary, miR‐493‐5p is a pivotal miRNA that modulates various oncogenes after its reexpression in liver cancer cells, suggesting that tumor suppressor miRNAs with a large spectrum of action could provide valuable tools for miRNA replacement therapies.

MEG3-derived miR-493-5p overcomes the oncogenic feature of IGF2-miR-483 loss of imprinting in hepatic cancer cells

Numerous studies have described the critical role played by microRNAs (miRNAs) in cancer progression and the potential of these small non-coding RNAs for diagnostic or therapeutic applications. However, the mechanisms responsible for the altered expression of miRNAs in malignant cells remain poorly understood. Herein, via epigenetic unmasking, we identified a group of miRNAs located in the imprinted delta like non-canonical Notch ligand 1 (DLK1)-maternally expressed 3 (MEG3) locus that were repressed in hepatic tumor cells. Notably, miR-493-5p epigenetic silencing was correlated with hypermethylation of the MEG3 differentially regulated region (DMR) in liver cancer cell lines and tumor tissues from patients. Experimental rescue of miR-493-5p promoted an anti-cancer response by hindering hepatocellular carcinoma (HCC) cell growth in vitro and tumor progression in vivo. We found that miR-493-5p mediated part of its tumor-suppressor activity by abrogating overexpression of insulin-like growth factor 2 (IGF2) and the IGF2-derived intronic oncomir miR-483-3p in HCC cells characterized by IGF2 loss of imprinting (LOI). In summary, this study describes an unknown miRNA-dependent regulatory mechanism between two distinct imprinted loci and a possible therapeutic window for liver cancer patients exhibiting IGF2-miR-483 LOI and amplification.

Development of miRNA-based therapeutic approaches for cancer patients

Over the past few decades, siRNA and miRNA have attracted a great deal of attention from researchers and clinicians. These molecules have been extensively studied from the standpoint of developing biopharmaceuticals against various diseases, including heart disease, diabetes and cancers. siRNA suppresses only a single target, whereas each miRNA regulates the expression of multiple target genes. More importantly, because miRNA are also secreted from cancer cells, and their aberrant expression is associated with tumor development and progression, they represent not only therapeutic targets but also promising biomarkers for diagnosis and prognosis. Therefore, miRNA may be more effective tools against cancers, in which multiple signal pathways are dysregulated. In this review, we summarize recent progress in the development of miRNA therapeutics for the treatment of cancer patients, and describe delivery systems for oligonucleotide therapeutics.

MicroRNA-493 targets STMN-1 and promotes hypoxia-induced epithelial cell cycle arrest in G2/M and renal fibrosis

Hypoxia plays an important role in the development of renal fibrosis. G₂/M arrest in renal tubular cells is an important pathway in the development of chronic kidney disease. It is unknown whether hypoxia leads to renal fibrosis via the regulation of G₂/M arrest in renal tubular epithelial cells. For the first time, to our knowledge, we showed that hypoxia induces G₂/M arrest in renal tubular cells leading to renal fibrosis, and microRNAs are involved in this regulation. We compared microRNA expression between hypoxia and normoxia in HK2 cells and found microRNA (miR)-493 to be highly expressed at 24 and 48 h after hypoxia. The overexpression of miR-493 reduced the expression of the cell cycle regulator, Stathmin (STMN)-1, and increased the percentage of G₂/M phase cells and profibrotic factors in HK2 cells. Targeting STMN-1 with short hairpin RNA produced an effect similar to that of miR-493 overexpression. On contrast, the miR-493 inhibitor reversed these effects in vitro. Consistent with these results, miR-493 sponge adeno-associated virus reduced the expression of profibrotic factors and increased STMN-1 in vivo. In summary, these results suggest that the miR-493-STMN-1 pathway contributes to hypoxia-induced tubular epithelial cell G₂/M arrest and renal fibrosis. Abrogating G₂/M arrest and blocking the miR-493-STMN-1 pathway will provide further insight for the development of antifibrosis therapy.-Liu, T., Liu, L., Liu, M., Du, R., Dang, Y., Bai, M., Zhang, L., Ma, F., Yang, X., Ning, X., Sun, S. MicroRNA-493 targets STMN-1 and promotes hypoxia-induced epithelial cell cycle arrest In G₂/M and renal fibrosis.

MicroRNA-493 is a prognostic factor in triple-negative breast cancer

Breast cancer is one of the most common malignant diseases in women. Triple‐negative breast cancer (TNBC) shows higher aggressiveness and recurrence rates than other subtypes, and there are no effective targets or tailored treatments for TNBC patients. Thus, finding effective prognostic markers for TNBC could help clinicians in their ability to care for their patients. We used tissue microarrays (TMAs) to detect microRNA‐493 (miR‐493) expression in breast cancer samples. A miRCURY LNA detection probe specific for miR‐493 was used in in situ hybridization assays. Staining results were reviewed by two independent pathologists and classified as high or low expression of miR‐493. Kaplan–Meier survival plots and multivariate Cox analysis were carried out to clarify the relationship between miR‐493 and survival. In the Kaplan–Meier analysis, patients with high miR‐493 expression had better disease‐free survival than patients with low miR‐493 expression. After adjusting for common clinicopathological factors in breast cancer, the expression level of miR‐493 was still a significant prognostic factor in breast cancer. Further subtype analysis revealed that miR‐493 expression levels were only significantly prognostic in TNBC patients. These results were validated in the Molecular Taxonomy of Breast Cancer International Consortium database for overall survival. We proved the prognostic role of miR‐493 in TNBC by using one of the largest breast cancer TMAs available and validated it in a large public RNA sequencing database.

Mutant KRAS promotes liver metastasis of colorectal cancer, in part, by upregulating the MEK-Sp1-DNMT1-miR-137-YB-1-IGF-IR signaling pathway

Although the role of insulin-like growth factor-I receptor (IGF-IR) in promoting colorectal liver metastasis is known, the mechanism by which IGF-IR is upregulated in colorectal cancer (CRC) is not defined. In this study, we obtained evidence that mutant KRAS transcriptionally activates IGF-IR gene expression through Y-box-binding protein (YB)-1 upregulation via a novel MEK-Sp1-DNMT1-miR-137 pathway in CRC cells. The mechanistic link between the tumor suppressive miR-137 and the translational regulation of YB-1 is intriguing because epigenetic silencing of miR-137 represents an early event in colorectal carcinogenesis due to promoter hypermethylation. This proposed signaling axis was further verified by the immunohistochemical evaluations of liver metastases from a cohort of 46 KRAS mutant CRC patients, which showed a significant correlation in the expression levels among Sp1, miR-137, YB-1, and IGF-1R. Moreover, suppression of the expression of YB-1 and IGF-IR via genetic knockdown or the pharmacological inhibition of MEK hampers KRAS-driven colorectal liver metastasis in our animal model studies. From a translational perspective, the identification of this KRAS-driven pathway might provide a mechanistic rationale for the use of a MEK inhibitor as an adjuvant, in combination with standard of care, to prevent the recurrence of colorectal liver metastasis in KRAS mutant CRC patients after receiving liver resection, which warrants further investigation.

MicroRNA-493 inhibits the proliferation and invasion of osteosarcoma cells through directly targeting specificity protein 1

Osteosarcoma (OS) is the most common type of primary bone tumor and accounts for ~60% of all malignant bone tumors in children and adolescents. A large number of studies have proposed that the dysregulated and dysfunctional microRNAs may serve important roles in the occurrence, progression and metastasis of various types of human cancer, including OS. MicroRNA-493 (miR-493) has been identified to act as a tumor suppressor in several types of human cancer. However, little is known regarding the expression pattern and clinical significance of miR-493 in OS. In the present study, reverse transcription-quantitative polymerase chain reaction analysis revealed that miR-493 was markedly downregulated in OS tissues and cell lines and a low miR-493 level were associated with distant metastasis and clinical stage. Furthermore, functional experiments demonstrated that enforced expression of miR-493 led to a significant decrease in OS cell proliferation and invasion in vitro. Furthermore, through bioinformatics analysis, specificity protein 1 (SP1) was identified as a direct target gene of miR-493 in OS. Its expression was upregulated in OS tissues and was negatively associated with miR-493 expression levels. Inhibition of SP1 expression also suppressed the proliferation and invasion of OS, exerting a similar effect to that induced by miR-493 overexpression. These results suggested that miR-493 inhibited OS cell proliferation and invasion through negative regulation of SP1. Therefore, miR-493/SP1 may represent a potential therapeutic target for the treatment of OS.

Lost in translation: The 3'-UTR of IGF1R as an ancient long noncoding RNA

Background and objectives

The insulin-like growth factor (IGF) signaling system is a major arena of intragenomic conflict over embryonic growth between imprinted genes of maternal and paternal origin and the IGF type 1 receptor (IGF1R) promotes proliferation of many human cancers. The 3'-untranslated region (3'-UTR) of the mouse Igf1r mRNA is targeted by miR-675-3p derived from the imprinted H19 long noncoding RNA. We undertook a comparative sequence analysis of vertebrate IGF1R 3'-UTRs to determine the evolutionary history of miR-675 target sequences and to identify conserved features that are likely to be involved in post-transcriptional regulation of IGF1R translation.

Methodology

Sequences of IGF1R 3'-UTRs were obtained from public databases and analyzed using publicly available algorithms.

Results

A very long 3'-UTR is a conserved feature of vertebrate IGF1R mRNAs. We found that some ancient microRNAs, such as let-7 and mir-182, have predicted binding sites that are conserved between cartilaginous fish and mammals. One very conserved region is targeted by multiple, maternally expressed imprinted microRNAs that appear to have evolved more recently than the targeted sequences.

Conclusions and implications

The conserved structures we identify in the IGF1R 3'-UTR are strong candidates for regulating cell proliferation during development and carcinogenesis. These conserved structures are now targeted by multiple imprinted microRNAs. These observations emphasize the central importance of IGF signaling pathways in the mediation of intragenomic conflicts over embryonic growth and identify possible targets for therapeutic interventions in cancer.

Targeting IGF1R pathway in cancer with microRNAs: How close are we?

Cancer of the head and neck are the most common cancers in India and account for 30% of all cancers. At molecular level, it could be attributed to the overexpression of growth factors like IGF1-R, EGFR, VEGF-R and deregulation of cell cycle regulators and tumor suppressors. IGF1-R is an emerging target in head and neck cancer treatment, because of its reported role in tumor development, progression and metastasis. IGF1R targeted agents are in advanced stages of clinical development. Nevertheless, these agents suffer from several disadvantages including acquired resistance and toxic side effects. Hence there is a need for developing newer agents targeting not only the receptor but also its downstream signaling. miRNAs are considered as master regulators of gene expression of multiple genes and has been widely reported to be a promising therapeutic strategy. This review discusses the present status of research in both these arenas and emphasizes the role of miRNA as a promising agent for biologic therapy.

Proteasome 26S subunit PSMD1 regulates breast cancer cell growth through p53 protein degradation

Endocrine therapy using antiestrogens and aromatase inhibitors is usually efficient to treat patients with hormone-sensitive breast cancer. Many patients with endocrine therapy, however, often acquire resistance. In the present study, we performed functional screening using short hairpin RNA library to dissect genes involved in antiestrogen tamoxifen resistance in MCF-7 breast cancer cells. We identified seven candidate genes that are associated with poor prognosis of breast cancer patients based on clinical dataset. The expression levels of six out of seven genes were higher in 4-hydroxytamoxifen (OHT) resistant MCF-7 (OHTR) cells compared with parental MCF-7 cells. Among the six selected genes, siRNA-mediated knockdown of PSMD1 and TSPAN12 markedly reduced the proliferation of OHTR cells. Notably, the knockdown of proteasome 26S subunit PSMD1 exhibited cell cycle arrest and the accumulation of p53 protein through inhibiting p53 protein degradation. In accordance with p53 accumulation, its target genes p21 and SFN were also upregulated by PSMD1 silencing. Taken together, PSMD1 was identified as a potential gene that plays a role in the development of tamoxifen resistance in breast cancer cells. These findings will provide a new insight for the mechanism underlying endocrine therapy resistance and a prognostic and therapeutic molecular target for advanced breast cancer.

MicroRNA-493-5p promotes apoptosis and suppresses proliferation and invasion in liver cancer cells by targeting VAMP2

The aim of the present study was to explore the role of miR‑493-5p in liver cancer tissues and cell lines, and its effect on cell behavioral characteristics. The expression of miR-493-5p was detected by reverse transcription-quantitative polymerase chain reaction (RT-qPCR) in liver cancer tissues and cell lines (hepatic cell line HL-7702 and the liver cancer cell lines HCCC-9810, HuH-7 and HepG2). In addition, the mechanism by which miR-493-5p mediates its effects was analyzed via the transfection of miR-493-5p mimic and negative control miRNA into HepG2 cells. The viability, proliferation, apoptosis and invasion of the cells were analyzed using MTT assay, flow cytometry and Transwell chamber experiments. Furthermore, the effect of miR-493-5p on the expression of vesicle associated membrane protein 2 (VAMP2) was assayed using a dual-luciferase reporter system, and VAMP2 protein levels were determined by western blot analysis. In addition, following the cotransfection of HepG2 cells with pcDNA3.1‑VAMP2 plasmid and miR‑493-5p mimic, the role of miR-493-5p as a regulator of VAMP2 was evaluated using MTT assay, flow cytometry and Transwell chamber experiments. RT-qPCR analysis indicated that the expression of miR-493-5p in liver cancer tissues and cell lines was decreased significantly compared with that in adjacent normal liver tissues and normal liver cell lines, respectively. Compared with the control group, the cells transfected with miR-493-5p mimic (the miR-493-5p overexpression group) exhibited reduced cell viability, a reduced percentage of cells in the S phase and an increased percentage of apoptotic cells. In addition, fewer cells passed through the Transwell membrane in the miR-493-5p overexpression group compared with the control group. In the dual-luciferase reporter assay, luciferase activity in the miR‑493-5p overexpression group was attenuated compared with that in the control group. In addition, western blot analysis indicated that the VAMP2 protein levels in the miR‑493-5p overexpression group were lower than those in the control group. Furthermore, in cells overexpressing miR-493-5p and VAMP2 simultaneously, the biological behavior of the cells, including cell viability, cell cycle and cell invasiveness, was significantly rescued compared with that of the control group transfected with miR‑493-5p alone. In conclusion, miR-493-5p is indicated to be a tumor suppressor gene, and is downregulated in human liver cancer. miR-493-5p overexpression promotes cell apoptosis and inhibits the proliferation and migration of liver cancer cells by negatively regulating the expression of VAMP. These observations suggest the potential of treating liver cancer by the overexpression of microRNA-493-5p.

Novel Mad2-targeting miR-493-3p controls mitotic fidelity and cancer cells' sensitivity to paclitaxel

The molecular pathways that contribute to the proliferation and drug response of cancer cells are highly complex and currently insufficiently characterized. We have identified a previously unknown microRNA-based mechanism that provides cancer cells means to stimulate tumorigenesis via increased genomic instability and, at the same time, evade the action of clinically utilized microtubule drugs. We demonstrate miR-493-3p to be a novel negative regulator of mitotic arrest deficient-2 (MAD2), an essential component of the spindle assembly checkpoint that monitors the fidelity of chromosome segregation. The microRNA targets the 3′ UTR of Mad2 mRNA thereby preventing translation of the Mad2 protein. In cancer cells, overexpression of miR-493-3p induced a premature mitotic exit that led to increased frequency of aneuploidy and cellular senescence in the progeny cells. Importantly, excess of the miR-493-3p conferred resistance of cancer cells to microtubule drugs. In human neoplasms, miR-493-3p and Mad2 expression alterations correlated with advanced ovarian cancer forms and high miR-493-3p levels were associated with reduced survival of ovarian and breast cancer patients with aggressive tumors, especially in the paclitaxel therapy arm. Our results suggest that intratumoral profiling of miR-493-3p and Mad2 levels can have diagnostic value in predicting the efficacy of taxane chemotherapy.

Epigenetic silencing of miR-493 increases the resistance to cisplatin in lung cancer by targeting tongue cancer resistance-related protein 1(TCRP1)

Background

The potential mechanisms regarding how methylation of microRNA(miRNA) CpG Island could regulate cancer cell chemo-resistance remains unclear. This study aims to explore the epigenetic dysregulation mechanism of miRNA-493 and the ability to modulate lung cancer cell chemotherapy resistance.

Methods

Real-time quantitative PCR (qRT-PCR) and In situ hybridization (ISH) were used to analyze the expression of miR-493 in lung cancer cell lines and tumor tissue, respectively. Bisulfite sequencing PCR (BSP) was used to exam the promoter CpG Island of miR-493. The effect of miR-493 on chemosensitivity was evaluated by cell viability assays, apoptosis assays and in vivo experiment. The DNA damage was measured by γ-H2AX immunofluorescence. Luciferase reporter assay was used to assess the target genes of miR-493. Expression of target proteins and downstream molecules were analyzed by Western blot.

Results

miR-493 is silenced in resistant lung cancer cell due to the aberrant DNA methylation. Enforced expression of miR-493 in lung cancer cells promotes chemotherapy sensitivity to cisplatin through impairing the DNA damage repair and increasing the cells apoptosis in vitro and in vivo. Furthermore, we identify that TCRP1 is a direct functional target of miR-493. Ectopic expression of TCRP1 attenuated increased apoptosis in miR-493-overexpressing lung cancer cells upon cisplatin treatment. Meanwhile, miR-493 level is negatively correlated with TCRP1 expression in lung cancer patients and TCRP1 expression were correlated with poor survival.

Conclusions

Our results highlight that hyper-methylation of miR-493CpG island might play important roles in the development of lung cancer chemo-resistance by targeting TCRP1, which might be used as a potential therapeutic target in preventing the chemo-resistance of lung cancer.

MicroRNA-493 suppresses hepatocellular carcinoma tumorigenesis through down-regulation of anthrax toxin receptor 1 (ANTXR1) and R-Spondin 2 (RSPO2)

Hepatocellular carcinoma (HCC) is known as a highly prevalent cancer with a poor prognosis and short survival time, despite intensive research and clinical efforts. Increasing numbers of studies have reported that microRNAs are involved in the malignant behavior of hepatocellular carcinoma cells via directly targeting multiple oncogenes or tumor suppressors. Here, we report that the expression of microRNA-493 (miR-493) is decreased in HCC cell lines and in tumor tissues. Overexpression of miR-493 in HCC cells dramatically inhibited cell proliferation and colony-formation in vitro and inhibited tumor formation of HCC cell xenografts in vivo. miR-493 also suppressed cell migration and invasion in HCC cell lines. Novel targets ANTXR1 and RSPO2 were confirmed to be suppressed by miR-493 directly, and overexpression of ANTXR1 and RSPO2 could restore tumorigenesis in miR-493 treated HCC cell. Moreover, Wnt/β-catenin signaling pathway, which was reported to be activated by ANTXR1 and RSPO2, was also inhibited by miR-493 overexpression and might be involved in anti-tumor function of miR-493. These findings suggest that miR-493 acts as a negative regulator in hepatocellular carcinoma progression and may be a potential therapeutic target for HCC.

Downregulation of miR-493 promoted melanoma proliferation by suppressing IRS4 expression

Accumulating evidence indicated that aberrantly expressed microRNAs play critical roles in the initiation and progression of human cancers. However, the underlying functions of miR-493 in human melanoma remains unknown. Here, our study found that miR-493 expression was downregulated in human melanoma tissues and cells. Overexpression of miR-493 suppressed cell proliferation and cell cycle in human melanoma cell line A375. IRS4 was defined as a target for downregulation by miR-493 and was confirmed by luciferase assay. We also found that knockdown of IRS4 counteracted the proliferation promotion by miR-493 inhibitor. In summary, these results demonstrated that miR-493 acts as a tumor suppressor and inhibits cell proliferation and cell cycle in human melanoma by directly targeting IRS4.

Sox2-dependent inhibition of p21 is associated with poor prognosis of endometrial cancer

Sex‐determining region Y‐box 2 (SOX2) is an essential factor involved in the self‐renewal and pluripotency of embryonic stem cells and has functions in cell survival and progression in many types of cancers. Here, we found that several endometrial cancer cell lines expressed SOX2, which was required for cell growth. Additionally, SOX2 overexpression regulated the expression of cyclin‐dependent kinase inhibitor 1A (CDKN1A), and SOX2 specifically bound to p21 promoter DNA in endometrial cancer cell lines expressing SOX2. Expressions of SOX2 in endometrial cancer patients were significantly correlated with histological grade and poor prognosis. Moreover, low p21 together with high SOX2 expressions in advanced endometrial cancer patients were associated with the most unfavorable outcomes of patients. These results indicated that simultaneous measurement of SOX2 and p21 expression in endometrial cancer patients may be a useful biomarker for patient prognosis.

miR-493-5p suppresses hepatocellular carcinoma cell proliferation through targeting GP73

Aberrant expression of miRNAs has been documented to play critical roles in the development and progression of hepatocellular carcinoma (HCC). However, the expression pattern, functional roles and regulatory mechanism of miR-493-5p in HCC have not been addressed. Herein, we found that miR-493-5p was significantly downregulated in HCC tissues and was tightly associated with tumor size, tumor differentiation grade and TNM stage of HCC patients. Overexpression of miR-493-5p inhibited HCC cell proliferation, arrested cell cycle in G0/G1 phase and induced cell apoptosis. Bioinformatical analysis and luciferase reporter assay further proved that Golgiprotein73 (GP73), an oncogene which was generally overexpressed in HCC, acted as a novel target of miR-493-5p. MiR-493-5p could inhibit GP73 both mRNA and protein expression. Moreover, overexpression of GP73 could reverse the inhibitory effects of miR-493-5p mediated HCC cell proliferation. In addition, upregulated GP73 in HCC tissues was inversely correlated with the miR-493-5p expression levels in the HCC tissues. Collectively, our present study demonstrates that miR-493-5p is downregulated in HCC and it can suppress the proliferation of HCC cells, partly at least, via directly targeting GP73. Besides, this study provides a novel insight into the mechanism of hepatocarcinogenesis and a promising blueprint for miR-493-5p-GP73 axis-oriented treatment of HCC.

Combined miRNA profiling and proteomics demonstrates that different miRNAs target a common set of proteins to promote colorectal cancer metastasis

The process of liver colonization in colorectal cancer remains poorly characterized. Here, we addressed the role of microRNA (miRNA) dysregulation in metastasis. We first compared miRNA expression profiles between colorectal cancer cell lines with different metastatic properties and then identified target proteins of the dysregulated miRNAs to establish their functions and prognostic value. We found that 38 miRNAs were differentially expressed between highly metastatic (KM12SM/SW620) and poorly metastatic (KM12C/SW480) cancer cell lines. After initial validation, we determined that three miRNAs (miR-424-3p, -503, and -1292) were overexpressed in metastatic colorectal cancer cell lines and human samples. Stable transduction of non-metastatic cells with each of the three miRNAs promoted metastatic properties in culture and increased liver colonization in vivo. Moreover, miR-424-3p and miR-1292 were associated with poor prognosis in human patients. A quantitative proteomic analysis of colorectal cancer cells transfected with miR-424-3p, miR-503, or miR-1292 identified alterations in 149, 129, or 121 proteins, respectively, with an extensive overlap of the target proteins of the three miRNAs. Importantly, down-regulation of two of these shared target proteins, CKB and UBA2, increased cell adhesion and proliferation in colorectal cancer cells. The capacity of distinct miRNAs to regulate the same mRNAs boosts the capacity of miRNAs to regulate cancer metastasis and underscores the necessity of targeting multiple miRNAs for effective cancer therapy. Copyright © 2017 Pathological Society of Great Britain and Ireland. Published by John Wiley & Sons, Ltd.

Snail-Modulated MicroRNA 493 Forms a Negative Feedback Loop with the Insulin-Like Growth Factor 1 Receptor Pathway and Blocks Tumorigenesis

In this study, we have identified one microRNA, microRNA 493 (miR-493), which could simultaneously and directly regulate multiple genes downstream of the insulin-like growth factor 1 receptor (IGF1R) pathway, including IGF1R, by binding with complementary sequences in the 3' untranslated region (UTR) of mRNAs of IGF1R, insulin receptor substrate 1 (IRS1), and mitogen-activated protein kinase 1 (MAPK1), thereby potentiating their inhibitory function at multiple levels in development and progression of cancers. This binding was further confirmed by pulldown of miR with AGO-2 antibody. Further, results from head and neck samples showed that miR-493 levels were significantly downregulated in tumors, with a concomitant increase in the expression of IGF1R and key downstream effectors. Functional studies from miR-493 overexpression cells and nude-mouse models revealed the tumor suppressor functions of miR-493. Regulation studies revealed that Snail binds to the miR-493 promoter and represses it. We found the existence of a dynamic negative feedback loop in the regulation of IGF1R and miR-493 mediated via Snail. Our study showed that nicotine treatment significantly decreases the levels of miR-493-with a concomitant increase in the levels of Snail-an indication of progression of cells toward tumorigenesis, reestablishing the role of tobacco as a major risk factor for head and neck cancers and elucidating the mechanism behind nicotine-mediated tumorigenesis.

Role of miR-15a in intervertebral disc degeneration through targeting MAP3K9

BACKGROUND

Accumulating evidence indicates that microRNAs are involved in various cellular processes, including cell proliferation, differentiation, apoptosis and metastasis. miR-15a is an important regulator of immune responses and angiogenesis, endogenous controls as well as potential targets and hallmarks of cancer. However, the role of miR-15a in intervertebral disc degeneration (IDD) has not been elucidated.

METHODS

Total RNA was extracted from degenerative nucleus pulposus (NP) tissues of 20 patients with IDD and NP cells, respectively. The expression levels of miR-15a were examined by quantitative real-time PCR. The stable overexpress or silence miR-15a expression cell lines and control cell lines were constructed by lentivirus infection. Subsequently, 3-(4,5-dimethylthia zol-2-yl)-2,5-diphenylte trazolium bromide (MTT) assay, flow cytometry test, TdT-mediated dUTP Nick-End Labeling (TUNEL) experiment, colony formation assay and western blot analysis were performed to detect the biological functions of miR-15a. Moreover, a luciferase reporter assay was conducted to confirm its target associations.

RESULTS

Herein, the results found that miR-15a was dramatically up-regulated in degenerative NP tissues and NP cells compared with the controls. Overexpression of miR-15a promoted NP cells proliferation and induced apoptosis. Moreover, apoptosis-related protein caspase-3 was significantly up-regulated and bcl-2 was observably down-regulated when NP cells were transfected with miR-15a mimics, while bax and caspase-3 were significantly down-regulated as well as bcl-2 was observably up-regulated when NP cells were transfected with miR-15a inhibitors. Further, luciferase reporter assay showed that MAP3K9, an upstream activator of MAPK kinase, was putative target of miR-15a. There was a negatively relationship between miR-15a and MAP3K9 expression in NP cells. In addition, knockdown MAP3K9 inhibited NP cells proliferation and promoted apoptosis, which further inhibited the activation of p38 and ERK MAPK pathway.

CONCLUSION

This present study revealed that miR-15a might be considered as a novel therapeutic target for IDD treatment.

miR-493 mediated DKK1 down-regulation confers proliferation, invasion and chemo-resistance in gastric cancer cells

In the present study, we demonstrated that the levels of DKK1 were decreased in serums and tissues of GC. DKK1 levels inversely correlated with tumor class, TNM stage, distant metastasis and lymph node metastasis of GC. GC patients with low DKK1 levels had a poor overall survival. DKK1 inhibited the proliferation of GC cells in vitro and in vivo. DKK1 also inhibited invasion, but enhanced chemo-sensitivity of GC cells. Mechanically, miR-493 levels increased in GC and directly targeted and down-regulated DKK1 expression. In agreement, miR-493 promoted proliferation of GC cells in vitro and in vivo. MiR-493 also promoted invasion and chemo-resistance of GC cells. However, DKK1 overexpression reversed the effects of miR-493 on proliferation, invasion and chemo-sensitivity. Thus, our results provide new insight for the role of miR-493/DKK1 axis in GC.

Stage-Wise Identification and Analysis of miRNA from Root-Knot Nematode Meloidogyne incognita

In this study, we investigated global changes in miRNAs of Meloidogyne incognita throughout its life cycle. Small RNA sequencing resulted in approximately 62, 38, 38, 35, and 39 Mb reads in the egg, J2, J3, J4, and female stages, respectively. Overall, we identified 2724 known and 383 novel miRNAs (read count > 10) from all stages, of which 169 known and 13 novel miRNA were common to all the five stages. Among the stage-specific miRNAs, miR-286 was highly expressed in eggs, miR-2401 in J2, miR-8 and miR-187 in J3, miR-6736 in J4, and miR-17 in the female stages. These miRNAs are reported to be involved in embryo and neural development, muscular function, and control of apoptosis. Cluster analysis indicated the presence of 91 miRNA clusters, of which 36 clusters were novel and identified in this study. Comparison of miRNA families with other nematodes showed 17 families to be commonly absent in animal parasitic nematodes and M. incognita. Validation of 43 predicted common and stage-specific miRNA by quantitative PCR (qPCR) indicated their expression in the nematode. Stage-wise exploration of M. incognita miRNAs has not been carried out before and this work presents information on common and stage-specific miRNAs of the root-knot nematode.

Posttranscriptional regulation of intestinal epithelial integrity by noncoding RNAs

Maintenance of the gut epithelial integrity under stressful environments requires epithelial cells to rapidly elicit changes in gene expression patterns to regulate their survival, adapt to stress, and keep epithelial homeostasis. Disruption of the intestinal epithelial integrity occurs commonly in patients with various critical illnesses, leading to the translocation of luminal toxic substances and bacteria to the blood stream. Recently, noncoding RNAs (ncRNAs) have emerged as a novel class of master regulators of gene expression and are fundamentally involved in many aspects of gut mucosal regeneration, protection, and epithelial barrier function. Here, we highlight the roles of several intestinal epithelial tissue-specific microRNAs, including miR-222, miR-29b, miR-503, and miR-195, and long ncRNAs such as H19 and SPRY4-IT1 in the regulation of cell proliferation, apoptosis, migration, and cell-to-cell interactions and also further analyze the mechanisms through which ncRNAs and their interactions with RNA-binding proteins modulate the stability and translation of target mRNAs. WIREs RNA 2017, 8:e1399. doi: 10.1002/wrna.1399 For further resources related to this article, please visit the WIREs website.

miR-493-5p attenuates the invasiveness and tumorigenicity in human breast cancer by targeting FUT4

Breast cancer is a leading cause of cancer-related mortality among women. Altered fucosylation was found to be closely associated with tumorigenesis and metastasis of breast cancer. MicroRNAs (miRNAs) are important regulators of cell proliferation and metastasis, and aberrant miRNA expression has been observed in breast cancer. The present study aimed to evaluate the level of fucosyltransferase IV (FUT4) and miR-493-5p in breast cancer and investigate their relationship. In the present study, we demonstrated the differential expressional profiles of FUT4 and miR‑493-5p in 29 clinical breast cancer tissues, matched adjacent tissue samples and two breast carcinoma cell lines (MCF-7 and MDA-MB-231). Briefly, altered expression levels of FUT4 modified the invasive activities and tumorigenicity of the MCF-7 and MDA-MB-231 cells. Further study demonstrated that miR-493-5p plays a role as a suppressor in breast cancer cell invasion and tumorigenicity. Moreover, the expression levels of miR-493-5p were inversely proportional to those of FUT4 both at the mRNA and protein levels. Luciferase reporter assays confirmed that miR‑493-5p bound to the 3'-untranslated (3'-UTR) region of FUT4, and inhibited the expression of FUT4 in breast cancer cells. Taken together, our data suggest that FUT4 may have a potential role in the treatment of breast cancer, as well as miR-493-5p is a novel regulator of invasiveness and tumorigenicity of breast cancer cells through targeting FUT4. The miR-493-5p/FUT4 pathway has therapeutic potential in breast cancer.

Targeting oncomiRNAs and mimicking tumor suppressor miRNAs: Νew trends in the development of miRNA therapeutic strategies in oncology (Review)

MicroRNA (miRNA or miR) therapeutics in cancer are based on targeting or mimicking miRNAs involved in cancer onset, progression, angiogenesis, epithelial-mesenchymal transition and metastasis. Several studies conclusively have demonstrated that miRNAs are deeply involved in tumor onset and progression, either behaving as tumor-promoting miRNAs (oncomiRNAs and metastamiRNAs) or as tumor suppressor miRNAs. This review focuses on the most promising examples potentially leading to the development of anticancer, miRNA-based therapeutic protocols. The inhibition of miRNA activity can be readily achieved by the use of miRNA inhibitors and oligomers, including RNA, DNA and DNA analogues (miRNA antisense therapy), small molecule inhibitors, miRNA sponges or through miRNA masking. On the contrary, the enhancement of miRNA function (miRNA replacement therapy) can be achieved by the use of modified miRNA mimetics, such as plasmid or lentiviral vectors carrying miRNA sequences. Combination strategies have been recently developed based on the observation that i) the combined administration of different antagomiR molecules induces greater antitumor effects and ii) some anti-miR molecules can sensitize drug-resistant tumor cell lines to therapeutic drugs. In this review, we discuss two additional issues: i) the combination of miRNA replacement therapy with drug administration and ii) the combination of antagomiR and miRNA replacement therapy. One of the solid results emerging from different independent studies is that miRNA replacement therapy can enhance the antitumor effects of the antitumor drugs. The second important conclusion of the reviewed studies is that the combination of anti-miRNA and miRNA replacement strategies may lead to excellent results, in terms of antitumor effects.

MicroRNA-493 regulates angiogenesis in a rat model of ischemic stroke by targeting MIF

MicroRNA-493 (miR-493) is known to suppress tumour metastasis and angiogenesis and its expression is decreased in stroke patients. In the present study, we investigated a role for miR-493 in regulating post-stroke angiogenesis. We found decreased expression of miR-493 in the ischemic boundary zone (IBZ) of rats subjected to middle cerebral artery occlusion (MCAO), and in rat brain microvascular endothelial cells (RBMECs) exposed to oxygen glucose deprivation. Down-regulating miR-493 with a lateral ventricular injection of antagomir-493, a synthetic miR-493 inhibitor, increased capillary density in the IBZ, decreased focal infarct volume and ameliorated neurologic deficits in rats subjected to MCAO. Intriguingly, MCAO also increased the expression of macrophage migration inhibitory factor (MIF) in the IBZ of rats; MIF expression was also increased in RBMECs exposed to oxygen glucose deprivation. We found that miR-493 directly targeted MIF, and that the protective effect of miR-493 inhibition in angiogenesis was attenuated by knocking down MIF. This effect could then be rescued by administration of recombinant MIF. Our findings highlight the importance of miR-493 in regulating angiogenesis after MCAO, and indicate that miR-493 is a potential therapeutic target in the treatment of stroke.

MiRNA Transcriptome Profiling of Spheroid-Enriched Cells with Cancer Stem Cell Properties in Human Breast MCF-7 Cell Line

Breast cancer is the second leading cause of cancer-related mortality worldwide as most patients often suffer cancer relapse. The reason is often attributed to the presence of cancer stem cells (CSCs). Recent studies revealed that dysregulation of microRNA (miRNA) are closely linked to breast cancer recurrence and metastasis. However, no specific study has comprehensively characterised the CSC characteristic and miRNA transcriptome in spheroid-enriched breast cells. This study described the generation of spheroid MCF-7 cell in serum-free condition and the comprehensive characterisation for their CSC properties. Subsequently, miRNA expression differences between the spheroid-enriched CSC cells and their parental cells were evaluated using next generation sequencing (NGS). Our results showed that the MCF-7 spheroid cells were enriched with CSCs properties, indicated by the ability to self-renew, increased expression of CSCs markers, and increased resistance to chemotherapeutic drugs. Additionally, spheroid-enriched CSCs possessed greater cell proliferation, migration, invasion, and wound healing ability. A total of 134 significantly (p<0.05) differentially expressed miRNAs were identified between spheroids and parental cells using miRNA-NGS. MiRNA-NGS analysis revealed 25 up-regulated and 109 down-regulated miRNAs which includes some miRNAs previously reported in the regulation of breast CSCs. A number of miRNAs (miR-4492, miR-4532, miR-381, miR-4508, miR-4448, miR-1296, and miR-365a) which have not been previously reported in breast cancer were found to show potential association with breast cancer chemoresistance and self-renewal capability. The gene ontology (GO) analysis showed that the predicted genes were enriched in the regulation of metabolic processes, gene expression, DNA binding, and hormone receptor binding. The corresponding pathway analyses inferred from the GO results were closely related to the function of signalling pathway, self-renewability, chemoresistance, tumorigenesis, cytoskeletal proteins, and metastasis in breast cancer. Based on these results, we proposed that certain miRNAs identified in this study could be used as new potential biomarkers for breast cancer stem cell diagnosis and targeted therapy.

MicroRNAs as growth regulators, their function and biomarker status in colorectal cancer

Gene expression is in part regulated by microRNAs (miRNAs). This review summarizes the current knowledge of miRNAs in colorectal cancer (CRC); their role as growth regulators, the mechanisms that regulate the miRNAs themselves and the potential of miRNAs as biomarkers. Although thousands of tissue samples and bodily fluids from CRC patients have been investigated for biomarker potential of miRNAs (>160 papers presented in a comprehensive tables), none single miRNA nor miRNA expression signatures are in clinical use for this disease. More than 500 miRNA-target pairs have been identified in CRC and we discuss how these regulatory nodes interconnect and affect signaling pathways in CRC progression.

Establishment and Characterization of an In Vitro Model of Ovarian Cancer Stem-like Cells with an Enhanced Proliferative Capacity

The establishment of cancer stem-like cell (CSC) culture systems may be instrumental in devising strategies to fight refractory cancers. Inhibition of the Rho kinase ROCK has been shown to favorably affect CSC spheroid cultures. In this study, we show how ROCK inhibition in human serous ovarian cancer (SOC) cells can help establish a CSC system, which illuminates cancer pathophysiology and its treatment in this setting. In the presence of a ROCK kinase inhibitor, spheroid cultures of SOC cells expressed characteristic CSC markers including ALDH1A1, CD133, and SOX2, along with differentiation and tumorigenic capabilities in mouse xenograft models of human SOC. High expression levels of ALDH, but not CD133, correlated with spheroid formation CSC marker expression and tumor forming capability. In clinical specimens of SOC, high levels of ALDH1A1 correlated with advanced stage and poor prognosis. Pharmacologic or genetic blockade of ALDH blocked cell proliferation and reduced expression of SOX2, the genetic ablation of which abolished spheroid formation, whereas SOX2 overexpression inhibited ALDH1A1 expression and blocked spheroid proliferation. Taken together, our findings illustrated a new method to culture human ovarian CSC, and they defined a reciprocal regulatory relationship between ALDH1A1 and SOX2, which impacts ovarian CSC proliferation and malignant progression.

MicroRNA Library-Based Functional Screening Identified Androgen-Sensitive miR-216a as a Player in Bicalutamide Resistance in Prostate Cancer

Prostate cancer is a major hormone-dependent tumor affecting men, and is often treated by hormone therapy at the primary stages. Despite its initial efficiency, the disease eventually acquires resistance, resulting in the recurrence of castration-resistant prostate cancer. Recent studies suggest that dysregulation of microRNA (miRNA) function is one of the mechanisms underlying hormone therapy resistance. Identification of critical miRNAs involved in endocrine resistance will therefore be important for developing therapeutic targets for prostate cancer. In the present study, we performed an miRNA library screening to identify anti-androgen bicalutamide resistance-related miRNAs in prostate cancer LNCaP cells. Cells were infected with a lentiviral miRNA library and subsequently maintained in media containing either bicalutamide or vehicle for a month. Microarray analysis determined the amounts of individual miRNA precursors and identified 2 retained miRNAs after one-month bicalutamide treatment. Of these, we further characterized miR-216a, because its function in prostate cancer remains unknown. miR-216a could be induced by dihydrotestosterone in LNCaP cells and ectopic expression of miR-216a inhibited bicalutamide-mediated growth suppression of LNCaP cells. Furthermore, a microarray dataset revealed that the expression levels of miR-216a were significantly higher in clinical prostate cancer than in benign samples. These results suggest that functional screening using an miRNA expression library could be useful for identifying novel miRNAs that contribute to bicalutamide resistance in prostate cancer.

MiR-493 suppresses the proliferation and invasion of gastric cancer cells by targeting RhoC

OBJECTIVES

MiRNAs have been proposed to be key regulators of tumorigenesis, progression and metastasis. However, their effect and prognostic value in gastric cancer is still poorly known.

MATERIALS AND METHODS

Gastric cancer cell lines were cultured. Tissue samples obtained from 36 gastric cancer patients were used for quantitative real-time PCR (qRT-PCR) analysis. The tissue microarrays (TMAs) consisted of 126 cases of gastric carcinoma that were used for In situ hybridisation (ISH). Lentivirus plasmids were co-transfected into 293FT cells. Cell migration was examined using wound-healing assays. Statistical analyses were performed using SPSS16.0 software.

RESULTS

In this study, we found that the expression levels of miR-493 were strongly down-regulated in gastric cancer and were associated with clinical stage and the presence of lymph node metastases. Moreover, miR-493 might independently predict OS and RFS in gastric cancer. We further found that up-regulation of miR-493 inhibited the proliferation and metastasis of gastric cancer cells, in vitro and in vivo. In addition, miR-493 directly targeted RhoC, which resulted in a marked reduction of the expression of mRNA and protein. This effect, in turn, led to a decreased ability of growth, invasion and metastasis in gastric cancer cells.

CONCLUSION

Taken together, our findings demonstrate that miR-493 is important for gastric cancer initiation and progression and holds promise as a prognostic biomarker to predict survival and relapse in gastric cancer. It is also a potential therapeutic tool to improve clinical outcomes in this disease.

The roles of microRNAs in the regulation of tumor metastasis

MicroRNAs (miRNAs) are small noncoding regulatory RNAs that regulate gene expression post-transcriptionally by either inhibiting protein translation or degrading target mRNAs. The differential expression profiles of miRNAs in different types of cancers and in the multi-step process of tumor progression indicate that miRNAs are involved in tumor onset, growth and progression. Metastasis is the most common cause of cancer-related mortality. Current evidence demonstrates that aberrant miRNA expression promotes or inhibits tumor metastasis by modulating the expression of numerous target genes. Therefore, the identification of metastasis-related miRNAs and a better understanding of the complex functions of miRNAs in tumor metastasis will provide potential diagnostic and prognostic biomarkers, as well as therapeutic targets for clinical application. Here, we review the functions of miRNAs in the control of multiple steps of tumor metastasis.

MicroRNAs as Regulator of Signaling Networks in Metastatic Colon Cancer

MicroRNAs (miRNAs) are a class of small, noncoding RNA molecules capable of regulating gene expression translationally and/or transcriptionally. A large number of evidence have demonstrated that miRNAs have a functional role in both physiological and pathological processes by regulating the expression of their target genes. Recently, the functionalities of miRNAs in the initiation, progression, angiogenesis, metastasis, and chemoresistance of tumors have gained increasing attentions. Particularly, the alteration of miRNA profiles has been correlated with the transformation and metastasis of various cancers, including colon cancer. This paper reports the latest findings on miRNAs involved in different signaling networks leading to colon cancer metastasis, mainly focusing on miRNA profiling and their roles in PTEN/PI3K, EGFR, TGFβ, and p53 signaling pathways of metastatic colon cancer. The potential of miRNAs used as biomarkers in the diagnosis, prognosis, and therapeutic targets in colon cancer is also discussed.

Liposarcoma miRNA signatures identified from genome-wide miRNA expression profiling

AIMS

To identify the miRNA expression profile of liposarcoma (LPS) that could facilitate detection of LPS, and provide the basis for further investigation of molecular-targeted therapeutic drugs.

MATERIALS & METHODS

A real-time quantitative PCR assay was performed to analyze the expression of 1888 miRNAs from 25 LPS tumor tissue samples, 16 samples of adipose tissue adjacent to the tumors and 18 normal adipose tissue samples from patients with LPS.

RESULTS

Ten dysregulated miRNAs were identified that effectively distinguished LPS tissue from adipose tissue and benign lipoma tissue, and LPS tumor tissues from normal adipose tissues in LPS patients. Furthermore, the expression profiles of miRNAs could also classify the subtype of LPS.

CONCLUSION

The identified miRNAs appear to be novel biomarkers for the detection of LPS, and may contribute to an understanding of the mechanisms of LPS tumorigenesis and its development, and further elucidate the characteristics of LPS subtypes.

Plasma circulating-microRNA profiles are useful for assessing prognosis in patients with cytogenetically normal myelodysplastic syndromes

Myelodysplastic syndromes are a heterogeneous group of clonal bone marrow hematopoietic stem cell disorders characterized by ineffective hematopoiesis and peripheral cytopenias. Chromosomal abnormalities and gene mutations have been shown to have essential roles in pathogenesis and correlate with prognosis. Molecular markers, however, are not integrated into currently used prognostic systems. The goal of this study is to identify plasma microRNAs useful for classification and risk stratification of myelodysplastic syndromes. We applied a novel, high-throughput digital quantification technology (NanoString) to profile microRNA expression in plasma samples of 72 patients with myelodysplastic syndromes and 12 healthy individuals. We correlated these results with overall survival. In patients with myelodysplastic syndromes associated with a diploid karyotype, we identified and validated a 7-microRNA signature as an independent predictor of survival with a predictive power of 75% accuracy (P=0.008), better than those of the International Prognostic Scoring Systems and the MD Anderson Prognostic Lower Risk Prognostic Model. We also identified differentially expressed plasma microRNAs in patients with myelodysplastic syndromes versus healthy individuals and between patients with myelodysplastic syndromes associated with different cytogenetic features. These results validate the utility of circulating-microRNA levels as noninvasive biomarkers that can inform the management of patients with myelodysplastic syndromes. Our findings also shed light on interactions of gene regulation pathways that are likely involved in the pathogenesis of myelodysplastic syndromes.

MicroRNA-574-3p, identified by microRNA library-based functional screening, modulates tamoxifen response in breast cancer

Most primary breast cancers express estrogen receptor α and can be treated via endocrine therapy using anti-estrogens such as tamoxifen; however, acquired endocrine resistance is a critical issue. To identify tamoxifen response-related microRNAs (miRNAs) in breast cancer, MCF-7 cells infected with a lentiviral miRNA library were treated with 4-hydroxytamoxifen (OHT) or vehicle for 4 weeks, and the amounts of individual miRNA precursors that had integrated into the genome were evaluated by microarray. Compared to the vehicle-treated cells, 5 'dropout' miRNAs, which were downregulated in OHT-treated cells, and 6 'retained' miRNAs, which were upregulated in OHT-treated cells, were identified. Of the dropout miRNAs, we found that miR-574-3p expression was downregulated in clinical breast cancer tissues as compared with their paired adjacent tissues. In addition, anti-miR-574-3p reversed tamoxifen-mediated suppression of MCF-7 cell growth. Clathrin heavy chain (CLTC) was identified as a miR-574-3p target gene by in silico algorithms and luciferase reporter assay using the 3' untranslated region of CLTC mRNA. Interestingly, loss and gain of miR-574-3p function in MCF-7 cells causes CLTC to be upregulated and downregulated, respectively. These results suggest that functional screening mediated by miRNA libraries can provide new insights into the genes essential for tamoxifen response in breast cancer.

Identifying and validating a combined mRNA and microRNA signature in response to imatinib treatment in a chronic myeloid leukemia cell line

Imatinib, a targeted tyrosine kinase inhibitor, is the gold standard for managing chronic myeloid leukemia (CML). Despite its wide application, imatinib resistance occurs in 20-30% of individuals with CML. Multiple potential biomarkers have been identified to predict imatinib response; however, the majority of them remain externally uncorroborated. In this study, we set out to systematically identify gene/microRNA (miRNA) whose expression changes are related to imatinib response. Through a Gene Expression Omnibus search, we identified two genome-wide expression datasets that contain expression changes in response to imatinib treatment in a CML cell line (K562): one for mRNA and the other for miRNA. Significantly differentially expressed transcripts/miRNAs post imatinib treatment were identified from both datasets. Three additional filtering criteria were applied 1) miRbase/miRanda predictive algorithm; 2) opposite direction of imatinib effect for genes and miRNAs; and 3) literature support. These criteria narrowed our candidate gene-miRNA to a single pair: IL8 and miR-493-5p. Using PCR we confirmed the significant up-regulation and down-regulation of miR-493-5p and IL8 by imatinib treatment, respectively in K562 cells. In addition, IL8 expression was significantly down-regulated in K562 cells 24 hours after miR-493-5p mimic transfection (p = 0.002). Furthermore, we demonstrated significant cellular growth inhibition after IL8 inhibition through either gene silencing or by over-expression of miR-493-5p (p = 0.0005 and p = 0.001 respectively). The IL8 inhibition also further sensitized K562 cells to imatinib cytotoxicity (p < 0.0001). Our study combined expression changes in transcriptome and miRNA after imatinib exposure to identify a potential gene-miRNA pair that is a critical target in imatinib response. Experimental validation supports the relationships between IL8 and miR-493-5p and between this gene-miRNA pair and imatinib sensitivity in a CML cell line. Our data suggests integrative analysis of multiple omic level data may provide new insight into biomarker discovery as well as mechanisms of imatinib resistance.

Regulation of RAB5C is important for the growth inhibitory effects of MiR-509 in human precursor-B acute lymphoblastic leukemia

MicroRNAs (miRs) regulate essentially all cellular processes, but few miRs are known to inhibit growth of precursor-B acute lymphoblastic leukemias (B-ALLs). We identified miR-509 via a human genome-wide gain-of-function screen for miRs that inhibit growth of the NALM6 human B-ALL cell line. MiR-509-mediated inhibition of NALM6 growth was confirmed by 3 independent assays. Enforced miR-509 expression inhibited 2 of 2 additional B-ALL cell lines tested, but not 3 non-B-ALL leukemia cell lines. MiR-509-transduced NALM6 cells had reduced numbers of actively proliferating cells and increased numbers of cells undergoing apoptosis. Using miR target prediction algorithms and a filtering strategy, RAB5C was predicted as a potentially relevant target of miR-509. Enforced miR-509 expression in NALM6 cells reduced RAB5C mRNA and protein levels, and RAB5C was demonstrated to be a direct target of miR-509. Knockdown of RAB5C in NALM6 cells recapitulated the growth inhibitory effects of miR-509. Co-expression of the RAB5C open reading frame without its 3' untranslated region (3'UTR) blocked the growth-inhibitory effect mediated by miR-509. These findings establish RAB5C as a target of miR-509 and an important regulator of B-ALL cell growth with potential as a therapeutic target.

Short hairpin RNA library-based functional screening identified ribosomal protein L31 that modulates prostate cancer cell growth via p53 pathway

Androgen receptor is a primary transcription factor involved in the proliferation of prostate cancer cells. Thus, hormone therapy using antiandrogens, such as bicalutamide, is a first-line treatment for the disease. Although hormone therapy initially reduces the tumor burden, many patients eventually relapse, developing tumors with acquired endocrine resistance. Elucidation of the molecular mechanisms underlying endocrine resistance is therefore a fundamental issue for the understanding and development of alternative therapeutics for advanced prostate cancer. In the present study, we performed short hairpin RNA (shRNA)-mediated functional screening to identify genes involved in bicalutamide-mediated effects on LNCaP prostate cancer cells. Among such candidate genes selected by screening using volcano plot analysis, ribosomal protein L31 (RPL31) was found to be essential for cell proliferation and cell-cycle progression in bicalutamide-resistant LNCaP (BicR) cells, based on small interfering RNA (siRNA)-mediated knockdown experiments. Of note, RPL31 mRNA is more abundantly expressed in BicR cells than in parental LNCaP cells, and clinical data from ONCOMINE and The Cancer Genome Altas showed that RPL31 is overexpressed in prostate carcinomas compared with benign prostate tissues. Intriguingly, protein levels of the tumor suppressor p53 and its targets, p21 and MDM2, were increased in LNCaP and BicR cells treated with RPL31 siRNA. We observed decreased degradation of p53 protein after RPL31 knockdown. Moreover, the suppression of growth and cell cycle upon RPL31 knockdown was partially recovered with p53 siRNA treatment. These results suggest that RPL31 is involved in bicalutamide-resistant growth of prostate cancer cells. The shRNA-mediated functional screen in this study provides new insight into the molecular mechanisms and therapeutic targets of advanced prostate cancer.

MicroRNA-493 suppresses tumor growth, invasion and metastasis of lung cancer by regulating E2F1

miRNAs have been proposed to be key regulators of progression and metastasis in cancer. However, an understanding of their roles and molecular mechanisms is needed to provide deeper insights for better therapeutic opportunities. In this study we investigated the role and mechanism of miR-493 in the development and progression of nonsmall-cell lung cancer (NSCLC). Our data indicated that the expression of miR-493 was markedly reduced in pulmonary carcinoma. The ectopic expression of miR-493 impaired cell growth and invasion in vitro and in vivo. Mechanically, miR-493 commonly directly targeted E2F1, which resulted in a robust reduction of the expression of mRNA and protein. This effect, in turn, decreased the growth, invasion and metastasis of lung cancer cells. Our findings highlight the importance of miR-493 dysfunction in promoting tumor progression, and implicate miR-493 as a potential therapeutic target in lung cancer.

Identification of microRNA-214 as a negative regulator of colorectal cancer liver metastasis by way of regulation of fibroblast growth factor receptor 1 expression

The purpose of this study was to identify microRNAs (miRNAs) involved in the pathology of colorectal cancer (CRC) liver metastasis and investigate their underlying mechanisms. A total of 39 miRNAs were identified to be differentially expressed between 16 primary CRC tissues with liver metastases and 16 CRC tissues without liver metastases from 32 patients by Affymetric miRNA microarrays. A panel of eight miRNAs were confirmed to be significantly and differentially expressed between CRC tissues with and without liver metastases through quantitative reverse-transcription polymerase chain reaction (RT-PCR) analysis in the 32 patients. In a validated cohort of 99 CRC patients (44 with and 55 without liver metastases), only miR-214 was validated to be significantly down-regulated in CRC with liver metastases, which was associated with an unfavorable prognosis. Ectopic expression of miR-214 suppressed proliferation, migration, and invasion in vitro, tumor growth and liver metastasis in an in vivo xenograft mouse model, whereas miR-214 knockdown promoted proliferation, migration, and invasion in CRC cell lines. Further studies indicated that fibroblast growth factor receptor 1 (FGFR1) was a potential target of miR-214. Restoring miR-214 expression in CRC cells decreased endogenous FGFR1 messenger RNA (mRNA) and protein levels. FGFR1 knockdown mimicked the tumor suppressive effect of miR-214 on CRC cells, while reintroduction of FGFR1 abolished the tumor suppressive effect of miR-214 on CRC cells. Moreover, miR-214 expression levels were inversely correlated with FGFR1 in CRC patients.

CONCLUSION

Down-regulation of miR-214 expression was correlated with increased FGFR1 expression levels, which may contribute to increased CRC liver metastasis. miR-214 may serve as a potential marker to predict survival, and the miR-214-FGFR1 axis may be a therapeutic target in CRC patients.

Post-transcriptional regulation of the tumor suppressor miR-139-5p and a network of miR-139-5p-mediated mRNA interactions in colorectal cancer

MicroRNAs play key roles in many biological processes, and are frequently dysregulated in tumor cells. However, there are few studies on how microRNAs are dysregulated. miR-139-5p, an important tumor suppressor, is often underexpressed in gastrointestinal cancer cells. Here, we describe post-transcriptional regulation of this intronic microRNA in human colorectal cancer. miR-139-5p is expressed independently of its overexpressed host gene PDE2A in colorectal cancer tissues and cell lines. The miR-139-5p target genes IGF1R, ROCK2 and RAP1B exert regulatory effects on the miR-139-5p expression level, relying on their ability to compete for miR-139-5p binding. These overexpressed target genes also regulate each others' protein levels through 3'-UTRs, thus regulating tumor cell growth and motility properties. Our study provides a mechanistic, experimentally validated rationale for intronic microRNA dysregulation in colorectal cancer, revealing novel oncogenic roles of IGF1R, ROCK2 and RAP1B 3'-UTRs.

Up-regulation of microRNA-145 associates with lymph node metastasis in colorectal cancer

Metastasis is the main cause of mortality in patients with solid tumours. Identifying the exact molecules associated with CRC metastasis may be crucial to understand the process, which might also be translated to the diagnosis and treatment of CRC. In this study, we investigate the association of microRNA expression patterns with the lymph node metastasis of colorectal cancer. Among these candidate miRNAs, the expression of miRNA-145 was significantly related to lymph node metastasis of CRC. Both in vitro and in vivo study demonstrated that up-regulation of miR-145 could improve the ability of migration and invasion of colorectal cancer cell, while no effect on proliferation was observed. The mechanism of this promotion is associated with the stabilization of Hsp-27, a protein which plays an important role in the promotion of metastasis. These results may be crucial to understanding CRC metastasis and may be translated to the diagnosis and treatment of CRC.