miR-520c and miR-373 upregulate MMP9 expression by targeting mTOR and SIRT1, and activate the Ras/Raf/MEK/Erk signaling pathway and NF-κB factor in human fibrosarcoma cells

ORMDL3 is associated with airway remodeling in asthma via the ERK/MMP-9 pathway

ORMDL sphingolipid biosynthesis regulator 3 (ORMDL3) has been previously implicated in asthma pathogenesis, its effect on airway remodeling remains to be elucidated. The present study examined the expression levels of ORMDL3 in a mouse model of asthma. Mice were divided into three groups: Asthmatic model (n=10), budesonide‑treated (n=10) and a control group (n=8). Asthma was induced by sensitization with ovalbumin (OVA) and aluminum hydroxide on day 1, 7 and 14. Subsequently mice were exposed to OVA three times per week from day 28. In order to investigate the mechanism of airway remodeling 100 µg/kg aerosol budesonide was administered to 6 animals prior to exposure to OVA. The condition of lung tissues was assessed through histology, and the expression levels of ORMDL3, phosphorylated‑extracellular‑signal regulated kinase (p‑ERK) and matrix metallopeptidase‑9 (MMP‑9) were quantified using immunohistochemistry, reverse transcription‑quantitative polymerase chain reaction and western blotting. A severe inflammatory response and airway remodeling were pretreatment with budesonide. Expression levels of ORMDL3, phosphorylated (p)‑ERK and MMP‑9 were significantly greater in the asthma‑model group; however, in the group pretreated with budesonide their expression was reduced. Expression levels of ORMDL3, p‑ERK and MMP‑9 were significantly positively correlated with bronchial wall thickness. ORMDL3 expression was significantly positively correlated with p‑ERK and MMP‑9. Therefore, increased ORMDL3 expression may induce the p‑ERK/MMP‑9 pathway to promote pathological airway remodeling in patients with asthma.

Selective activation of miRNAs of the primate-specific chromosome 19 miRNA cluster (C19MC) in cancer and stem cells and possible contribution to regulation of apoptosis

Background

The human chromosome 19 miRNA cluster (C19MC) of 43 genes is a primate-specific miRNA cluster that may have biological significance in the genetic complexity of the primate. Despite previous reports on individual C19MC miRNA expression in cancer and stem cells, systematic studies on C19MC miRNA expression and biological functions are lacking.

Results

Cluster-wide C19MC miRNA expression profiling by microarray analysis showed wholesome C19MC activation in embryonic stem cells (ESCs) and induced pluripotent stem cells (iPSCs). However, in multipotent adipose-derived mesenchymal stem cells (MSCs) and a unipotent human white pre-adipocyte cell line, only selected C19MC miRNAs were expressed. MiRNA copy number analysis also showed selective C19MC expression in cancer cells with expression patterns highly similar to those in MSCs, suggesting similar miRNA regulatory mechanisms in these cells. Selective miRNA expression also suggests complex transcriptional mechanism(s) regulating C19MC expression under specific cellular and pathological conditions. Bioinformatics analysis showed that sixteen of the C19MC miRNAs share the same “AAGUGC” seed sequence with members of the miR-302/-372 family, which are known cellular reprogramming factors. In particular, C19MC-AAGUGC-miRNAs with the nucleotides 2-7 canonical seed position as in miR-302/-372 miRNAs, may play similar roles as miR-302/-372 in induced pluripotency. A biased 3p-arm selection of the C19MC-AAGUGC-miRNAs was observed indicating that targets of the 3p species of these miRNAs may be biologically significant in regulating stemness. Furthermore, bioinformatics analysis of the putative targets of the C19MC-AAGUGC-miRNAs predicted significant involvement of signaling pathways in reprogramming, many of which contribute to promoting apoptosis by indirect activation of the pro-apoptotic proteins BAK/BAX via suppression of genes of the cell survival pathways, or by enhancing caspase-8 activation through targeting inhibitors of TRAIL-inducing apoptosis.

Conclusions

This work demonstrated selective C19MC expression in MSCs and cancer cells, and, through miRNA profiling and bioinformatics analysis, predicted C19MC modulation of apoptosis in induced pluripotency and tumorigenesis.

Electronic supplementary material

The online version of this article (doi:10.1186/s12929-017-0326-z) contains supplementary material, which is available to authorized users.

MicroRNA-520c enhances cell proliferation, migration, and invasion by suppressing IRF2 in gastric cancer

Dysregulation of microRNA (miRNA) is actively involved in the development and progression of gastric cancer (GC). MiR‐520c was previously found to be overexpressed in GC specimens and cells. However, the clinical significance of miR‐520c and its biological function in GC remain largely unknown. Here, we found that miR‐520c expression in GC tissues was significantly increased compared to normal adjacent gastric tissues. Its increased level was prominently correlated with poor clinical parameters and prognosis of GC patients. Accordingly, the expression of miR‐520c was obviously elevated in GC cell lines as compared with gastric epithelial cells. Overexpression of miR‐520c in N‐87 cells significantly increased the proliferative ability, migration, and invasion of cancer cells, while miR‐520c silencing suppressed MKN‐45 cell proliferation, migration, and invasion in vitro. Mechanically, miR‐520c inversely regulated interferon regulatory factor 2 (IRF2) abundance in GC cells. Herein, IRF2 was found to be a downstream target of miR‐520c in GC. Furthermore, IRF2 was down‐regulated in GC tissues compared to nontumor tissues. An inverse correlation between IRF2 and miR‐520c expression was observed in GC cases. Taken together, miR‐520c may serve as a prognostic predictor and a therapeutic target for GC patients.

Up-regulation of cathepsin S expression by HSP90 and 5-HT7 receptor-dependent serotonin signaling correlates with triple negativity of human breast cancer

PURPOSE

Cathepsin S (CTSS) is expressed in a variety of cancers and stimulates tumor progression. However, the regulatory mechanism and role of CTSS in breast cancer progression are poorly understood. The aim of this study was to examine the relationships between CTSS expression and breast cancer grade and stage, and the signaling molecules involved in CTSS expression.

METHODS

Immunohistochemical staining was performed in tissue microarray sections of 1451 human invasive breast cancer samples to determine epithelial (E-CTSS) and stromal CTSS (S-CTSS) expression. Gene and protein expression levels in human breast cancer cell lines were measured by polymerase chain reaction and western blotting. Small interfering RNA transfection and a Matrigel transwell invasion assay were used to confirm the signaling pathways regulating CTSS expression.

RESULTS

In patient tumor tissue blocks, high grade, late stage, and triple negativity were associated with elevated CTSS protein expression, and expression levels were related to the clinical outcomes of patients with invasive breast cancer. CTSS expression was also higher in triple-negative breast cancer (TNBC) cell lines than in hormone-responsive cells, and CTSS expression patterns matched those of tryptophan hydroxylase 1 (TPH1) and 5-hydroxytryptamine receptor 7 (5-HT₇). Treatment of TNBC cells (MDA-MB-231 and HCC-1395) with 5-HT significantly enhanced CTSS protein expression, whereas pharmacological inhibition or knockdown of 5-HT₇ significantly inhibited its expression. Correspondingly, cancer cell invasion was increased by 5-HT treatment and suppressed by 5-HT₇ knockdown. The expression of CTSS was regulated by PI3K/Akt and Ras/Raf/MAPK signaling pathways, and these signaling pathways were stabilized by HSP90 and enhanced by the 5-HT₇ receptor-dependent autocrine effect of 5-HT in TNBC cells.

CONCLUSION

Our findings suggest CTSS as a candidate target for development of a strategy to inhibit breast cancer invasion, and indicate that HSP90 and 5-HT₇ (regulators of CTSS) should be considered as alternative targets for the management of TNBC invasion and metastasis.

The roles of microRNAs related with progression and metastasis in human cancers

Metastasis is an important factor in predicting the prognosis of the patients with cancers and contributes to high cancer-related mortality. Recent studies indicated that microRNAs (miRNAs) played a functional role in the initiation and progression of human malignancies. MicroRNAs are small non-coding RNAs of about 22 nucleotides in length that can induce messenger RNA (mRNA) degradation or repress mRNA translation by binding to the 3' untranslated region (3'-UTR) of their target genes. Overwhelming reports indicated that miRNAs could regulate cancer invasion and metastasis via epithelial-to-mesenchymal transition (EMT)-related and/or non-EMT-related mechanisms. In this review, we concentrate on the underlying mechanisms of miRNAs in regulating cancer progression and metastasis.

Who watches the watchmen? Regulation of the expression and activity of sirtuins

Sirtuins (SIRT1-7) are a family of nicotine adenine dinucleotide (NAD⁺)-dependent enzymes that catalyze post-translational modifications of proteins. Together, they regulate crucial cellular functions and are traditionally associated with aging and longevity. Dysregulation of sirtuins plays an important role in major diseases, including cancer and metabolic, cardiac, and neurodegerative diseases. They are extensively regulated in response to a wide range of stimuli, including nutritional and metabolic challenges, inflammatory signals or hypoxic and oxidative stress. Each sirtuin is regulated individually in a tissue- and cell-specific manner. The control of sirtuin expression involves all the major points of regulation, including transcriptional and post-translational mechanisms and microRNAs. Collectively, these mechanisms control the protein levels, localization, and enzymatic activity of sirtuins. In many cases, the regulators of sirtuin expression are also their substrates, which lead to formation of intricate regulatory networks and extensive feedback loops. In this review, we highlight the mechanisms mediating the physiologic and pathologic regulation of sirtuin expression and activity. We also discuss the consequences of this regulation on sirtuin function and cellular physiology.-Buler, M., Andersson, U., Hakkola, J. Who watches the watchmen? Regulation of the expression and activity of sirtuins.

MiR-373 drives the epithelial-to-mesenchymal transition and metastasis via the miR-373-TXNIP-HIF1α-TWIST signaling axis in breast cancer

Our previous proteomics study revealed that thioredoxin-interacting protein (TXNIP) was down-regulated by miR-373. However, little is known of the mechanism by which miR-373 decreases TXNIP to stimulate metastasis. In this study, we show that miR-373 promotes the epithelial-to-mesenchymal transition (EMT) in breast cancer. MiR-373 suppresses TXNIP by binding to the 3'UTR of TXNIP, which in turn, induces cancer cell EMT and metastasis. TXNIP co-expression, but not the TXNIP-3'UTR, reverses the enhancement of EMT, migration, invasion and metastasis induced by miR-373. MiR-373 stimulates EMT, migration and invasion through TXNIP-dependent reactive oxygen species (ROS) reduction. Mechanistically, miR-373 up-regulates and activates the HIF1α-TWIST signaling axis via the TXNIP pathway. Consequently, TWIST induces miR-373 expression by binding to the promoter of the miR-371-373 cluster. Clinically, miR-373 is negatively associated with TXNIP and positively associated with HIF1α and TWIST, and activation of the miR-373-TXNIP-HIF1α-TWIST signaling axis is correlated with a worse outcome in patients with breast cancer. This signaling axis may be an independent prognostic factor for patients with breast cancer.

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-373 Inhibits Glioma Cell U251 Migration and Invasion by Down-Regulating CD44 and TGFBR2

Glioblastoma multiforme (GBM) is the most malignant glioma, unveiling the underlying mechanisms of its aggressiveness could promote the discovery of potential targets for effective treatment. MicroRNAs (miRNAs) are important participants in both development and disease, its involvement in cancers has long been recognized. In this study, we investigated the role of miRNA-373 (miR-373) in GBM cell line U251, demonstrated that although miR-373 does not affect cell growth of U251, it inhibits migration and invasion of U251. Forced expression of miR-373 down-regulates the expressions CD44 and TGFBR2, while knockdown of CD44 and TGFBR2 presents the similar phenotype as miR-373 overexpression, suggesting that CD44 and TGFBR2 are functional targets of miR-373, down-regulation of CD44 and TGFBR2 by miR-373 are partly responsible for the migration, and invasion suppressive role of miR-373 in U251.

[MiR-373-3p Promotes Invasion and Metastasis of Lung Adenocarcinoma Cells]

背景与目的

肺癌位居全球癌症相关死亡率的首位，其中肿瘤转移是导致肺癌患者死亡的主要原因，研究表明miR-373与多种肿瘤细胞的侵袭转移有密切关系。本研究旨在探讨miR-373-3p在非小细胞肺癌(non-small cell lung cancer, NSCLC)中的表达情况及其对肺腺癌细胞侵袭转移能力的影响。

方法

利用qRT-PCR法检测miR-373-3p在NSCLC组织和肺腺癌细胞株中的表达。瞬时转染hsa-miR-373-3p的mimics和inhibitor至肺腺癌H1299和A549细胞株中，利用Transwell小室检测转染后肺腺癌细胞侵袭转移能力的改变，Western blot检测转染后肺腺癌细胞中基质金属蛋白酶-9(matrix metalloproteinase-9, MMP-9)及MMP-14蛋白水平的改变。

结果

miR-373-3p在51例NSCLC组织和5种肺腺癌细胞株中均明显高表达。在miR-373-3p低表达的H1299细胞中过表达miR-373-3p，细胞的侵袭转移能力明显提高，同时MMP-9及MMP-14的表达上调；在miR-373-3p高表达的A549细胞中抑制miR-373-3p表达，细胞的侵袭转移能力下降，并且下调MMP-9和MMP-14的表达。

结论

miR-373-3p可能通过正向调节MMP-9、MMP-14的表达而促进肺腺癌细胞的侵袭转移能力。

Rapamycin Inhibits Oxidized Low Density Lipoprotein Uptake in Human Umbilical Vein Endothelial Cells via mTOR/NF-κB/LOX-1 Pathway

Background

Lectin-like oxidized low-density lipoprotein-1 (LOX-1) is the major receptor for oxidized low density lipoprotein (ox-LDL) uptake in human umbilical vein endothelial cells (HUVECs). Previously, we found that rapamycin inhibited ox-LDL accumulation in HUVECs, and this effect was related to its role in increasing the activity of autophagy-lysosome pathway. In this study, we determined whether rapamycin could also reduce ox-LDL uptake in HUVECs and investigated the underlying signaling mechanisms.

Results

Flow cytometry and live cell imaging showed that rapamycin reduced Dil-ox-LDL accumulation in HUVECs. Furthermore, rapamycin reduced the ox-LDL-induced increase in LOX-1 mRNA and protein levels. Western blotting showed that rapamycin inhibited mechanistic target of rapamycin (mTOR), p70s6k and IκBα phosphorylation triggered by ox-LDL. Flow cytometry implied that mTOR, NF-κB knockdown and NF-κB inhibitors significantly reduced Dil-ox-LDL uptake. Moreover, immunofluorescent staining showed that rapamycin reduced the accumulation of p65 in the nucleus after ox-LDL treatment for 30 h. mTOR knockdown decreased LOX-1 protein production and IκBα phosphorylation induced by ox-LDL. NF-κB knockdown and NF-κB inhibitors reduced LOX-1 protein production, but did not inhibit mTOR phosphorylation stimulated by ox-LDL.

Conclusions

These findings demonstrate that rapamycin reduce mTOR phosphorylation and subsequently inhibit NF-κB activation and suppresses LOX-1, resulting in a reduction in ox-LDL uptake in HUVECs.

Tissue Factor Regulation by miR-520g in Primitive Neuronal Brain Tumor Cells: A Possible Link between Oncomirs and the Vascular Tumor Microenvironment

Pediatric embryonal brain tumors with multilayered rosettes demonstrate a unique oncogenic amplification of the chromosome 19 miRNA cluster, C19MC. Because oncogenic lesions often cause deregulation of vascular effectors, including procoagulant tissue factor (TF), this study explores whether there is a link between C19MC oncogenic miRNAs (oncomirs) and the coagulant properties of cancer cells, a question previously not studied. In a pediatric embryonal brain tumor tissue microarray, we observed an association between C19MC amplification and reduced fibrin content and TF expression, indicative of reduced procoagulant activity. In medulloblastoma cell lines (DAOY and UW228) engineered to express miR-520g, a biologically active constituent of the C19MC cluster, we observed reduced TF expression, procoagulant and TF signaling activities (responses to factor VIIa stimulation), and diminished TF emission as cargo of extracellular vesicles. Antimir and luciferase reporter assays revealed a specific and direct effect of miR-520g on the TF 3' untranslated region. Although the endogenous MIR520G locus is methylated in differentiated cells, exposure of DAOY cells to 5-aza-2'-deoxycytidine or their growth as stem cell-like spheres up-regulated endogenous miR-520g with a coincident reduction in TF expression. We propose that the properties of tumors harboring oncomirs may include unique alterations of the vascular microenvironment, including deregulation of TF, with a possible impact on the biology, therapy, and hemostatic adverse effects of both disease progression and treatment.

miR-370 and miR-373 regulate the pathogenesis of osteoarthritis by modulating one-carbon metabolism via SHMT-2 and MECP-2, respectively

The aim of this study was to determine the mechanism underlying the association between one-carbon metabolism and DNA methylation during chronic degenerative joint disorder, osteoarthritis (OA). Articular chondrocytes were isolated from human OA cartilage and normal cartilage biopsied, and the degree of cartilage degradation was determined by safranin O staining. We found that the expression levels of SHMT-2 and MECP-2 were increased in OA chondrocytes, and 3′UTR reporter assays showed that SHMT-2 and MECP-2 are the direct targets of miR-370 and miR-373, respectively, in human articular chondrocytes. Our experiments showed that miR-370 and miR-373 levels were significantly lower in OA chondrocytes compared to normal chondrocytes. Overexpression of miR-370 or miR-373, or knockdown of SHMT-2 or MECP-2 reduced both MMP-13 expression and apoptotic cell death in cultured OA chondrocytes. In vivo, we found that introduction of miR-370 or miR-373 into the cartilage of mice that had undergone destabilization of the medial meniscus (DMM) surgery significantly reduced the cartilage destruction in this model, whereas introduction of SHMT-2 or MECP-2 increased the severity of cartilage destruction. Together, these results show that miR-370 and miR-373 contribute to the pathogenesis of OA and act as negative regulators of SHMT-2 and MECP-2, respectively.

MicroRNA miR-182 cluster mediated modulation of RECK without changes in cell surface membrane type-1 matrix metalloproteinase (MT1-MMP)

Cell surface localized membrane type 1-matrix metalloproteinase (MT1-MMP) plays an important role in physiological and pathological processes and its function can be regulated by proteins such as RECK. We examined the ability of miR-182 (one of the miR-183 cluster miRNAs), which can target RECK, to control cell surface MT1-MMP activity. Expression of RECK mRNA and protein was increased with anti-miRs to miR-182, miR-183 or miR-96 in HT1080 fibrosarcoma cells, but, decreased RECK mRNA and increased its protein in the benign prostatic hyperplasia cell line BPH-1. Treatment of BPH-1 and HT-1080 cells with the anti-miRs did not change the level of cell surface MT1-MMP activity, nor their rate of migration in an in vitro wound-healing assay. Trichostatin A (TSA) did not increase the level of RECK, but blocked cell surface MT1-MMP activity and decreased cell motility. Anti-miRs mediated increased RECK levels did not interfere with cell surface MT1-MMP function, and TSA may block cell surface localization of MT1-MMP by a mechanism independent of RECK.

The circular relationship between matrix metalloproteinase-9 and inflammation following myocardial infarction

Matrix metalloproteinase-9 (MMP-9) regulates remodeling of the left ventricle after myocardial infarction (MI) and is tightly linked to the inflammatory response. The inflammatory response serves to recruit leukocytes as part of the wound healing reaction to the MI injury, and infiltrated leukocytes produce cytokines and chemokines that stimulate MMP-9 production and release. In turn, MMP-9 proteolyzes cytokines and chemokines. Although in most cases, MMP-9 cleavage of the cytokine or chemokine substrate serves to increase activity, there are cases where cleavage results in reduced activity. Global MMP-9 deletion in mouse MI models has proven beneficial, suggesting inhibition of some aspects of MMP-9 activity may be valuable for clinical use. At the same time, overexpression of MMP-9 in macrophages has also proven beneficial, indicating that we still do not fully understand the complexity of MMP-9 mechanisms of action. In this review, we summarize the cycle of MMP-9 effects on cytokine production and cleavage to regulate leukocyte functions. Although we use MI as the example process, similar events occur in other inflammatory and wound healing conditions.

Epigenetic silencing of ITGA2 by MiR-373 promotes cell migration in breast cancer

The loss of ITGA2 plays an important role in cancer metastasis in several solid cancers. However, the molecular mechanism of ITGA2 loss in primary cancers remains unclear. In this study, we found that a lower ITGA2 protein level was observed in breast cancers compared to adjacent non-cancerous breast tissues. Interestingly, the reduction degree of ITGA2 at the protein level was far more than that at the mRNA level. We further showed that the translation of ITGA2 mRNA was directly inhibited by miR-373 through binding to ITGA2-3’UTR. Silencing of ITGA2 detached cell-cell interactions, induced the deploymerization of stress fiber F-actin and stimulated cancer cell migration, similar to the effect of miR-373 over-expression. The co-expression of ITGA2, not ITGA2-3’UTR, could abrogate miR-373-induced cancer cell migration because that the expression of ITGA2-3’UTR was inhibited by co-transfected miR-373. ITGA2 protein level was inversely associated with miR-373 level in breast cancers (r = -0.663, P<0.001). 73.33% of breast cancer patients with high miR-373 and low ITGA2 expression exhibited the lymph node-positive metastases. Together, our results show that epigenetic silencing of ITGA2 by miR-373 stimulates breast cancer migration, and miR-373^high/ITGA2^low may be as a prognosis biomarker for breast cancer patients.

The Oncogenic Response to MiR-335 Is Associated with Cell Surface Expression of Membrane-Type 1 Matrix Metalloproteinase (MT1-MMP) Activity

MicroRNA miR-335 has been reported to have both tumor suppressor and oncogenic activities. In order to determine possible tissue and cell type differences in response to miR-335, we examined the effect of miR-335 on cell expression of MT1-MMP, a proteinase commonly expressed in tumors and associated with cell proliferation and migration. miR-335 increased cell surface expression of MT1-MMP in fibrosarcoma HT-1080 and benign prostate BPH-1 cells, but not in prostate LNCaP or breast MCF-7 tumor cells. miR-335 stimulated proliferation and cell migration in a wound healing in vitro assay in HT-1080, BPH-1, and U87 glioblastoma cells, cells which demonstrated significant cell surface expression of MT1-MMP. In contrast, miR-335 did not affect proliferation or migration in cells without a prominent plasma membrane associated MT1-MMP activity. Our data suggest that differences in response to miR-335 by tumor cells may lie in part in the mechanism of regulation of MT1-MMP production.

Dual-Functions of miR-373 and miR-520c by Differently Regulating the Activities of MMP2 and MMP9

MicroRNA-520c (miR-520c) and microRNA-373 (miR-373) are originally characterized as both oncogenes and tumor suppressors in different types of human cancers. In this study, we found that translation of mRNA of MT1-MMP, an oncogene related to tumor metastasis, was well inhibited by miR-520c and miR-373 in several types of human cancer cells. Our experimental data demonstrated that these two microRNAs inhibited the translation of mRNA of MT1-MMP and down-regulated its proteolytic enzyme activities via targeting 3'UTR of mRNA of MT1-MMP, further decreased activating proMMP2 into active MMP2 in fibrosarcoma HT1080, benign prostatic hyperplasia epithelial cell BPH-1 and glioblastoma U87GM. More interestingly, from the effects of microRNAs on cell functions, we found that cell growth were all blocked on fibronectin and type IV collagen coated plates and also in three-dimension type I collagen lattice but enhanced only in HT1080 cells on type IV collagen coated plates and in three-dimension type I collagen lattice; cell migration results showed the same effect as that of cell growth. The difference was due to up-regulating the expression of MMP9 gene by miR-520c and miR-373 in HT1080 cells but not in BPH-1 and U87GM cells. Our findings suggest that miR-520c and miR-373, which have different roles in different type of cancer via regulating the translation of mRNA of MT1-MMP and the expression of MMP9 gene, might have an important clue on clinic when selecting the therapeutic regimen and finding new drugs for intervention in different kinds of cancer.

MicroRNAs as potential target in human bone and soft tissue sarcoma therapeutics

Sarcomas are highly aggressive heterogeneous tumors that are mesenchymal in origin. There have been vast advancements on identifying diagnostic markers for sarcomas including chromosomal translocations, but very little progress has been made to identify targeted therapies against them. The tumor heterogeneity, genetic complexity and the lack of drug studies make it challenging to recognize the potential targets and also accounts for the inadequate treatments in sarcomas. In recent years, microRNAs that are a part of small non-coding RNAs have shown promising results as potential diagnostic and prognostic biomarkers in multiple sarcoma types. This review focuses on the current knowledge of the microRNAs that are deregulated in sarcomas, and an insight on the strategies to target these microRNAs that are essential for developing improved therapies for various human sarcomas.

Diverse functions of miR-373 in cancer

MicroRNAs (miRNAs) are small noncoding RNAs that regulate gene expression post-transcriptionally. They are involved in almost all cellular processes, and many have been described as potential oncogenes or tumor suppressors. MicroRNA-373 (miR-373), which was first identified as a human embryonic stem cell (ESC)-specific miRNA, is suggested to be implicated in the regulation of cell proliferation, apoptosis, senescence, migration and invasion, as well as DNA damage repair following hypoxia stress. Deregulation of miR-373 has been demonstrated in a number of cancers, whether it acts as an oncogene or a tumor suppressor, however, seems to be context dependent. In this review, we focus on the diverse functions of miR-373 and its implication in cancers.

Unraveling novel TF-miRNA regulatory crosstalk in metastasis of Soft Tissue Sarcoma

Cancer metastasis is a disease of extreme clinical relevance, as it is responsible for more than 90% of cancer-associated mortality. The molecular mechanism and critical regulators involved in this complex multi-stage process of metastasis is poorly deciphered in soft tissue sarcomas (STS), a heterogeneous group of rare tumors with high metastatic potential. Therefore, we aimed at identifying miRNA and transcription factor (TF) regulatory networks and paths in STS metastasis. We integrated mRNA and miRNA expression profiles with curated regulations (TF→gene, TF→miRNA, miRNA→gene) from different databases and constructed a potentially active regulatory sub-network in STS metastasis. From functional and topological analysis, we found nine novel regulators of Notch signaling sub-network which are conjectured to play critical role in metastasis of STS. This illustrated that the sub-network is promising for identification of critical regulators. Further analysis deploying our developed tool ‘RiNAcyc’ and computing coverage ratio of known STS associated genes and miRNAs identified a 15 node active path. This potential path highlights the crucial role of BMP2, hsa-miR-24, AP2 and MYC as the up-stream regulators of the path and hsa-miR-215 and TYMS as potential indicator of chemotherapeutic benefit in STS metastasis.

Tissue elasticity regulated tumor gene expression: implication for diagnostic biomarkers of primitive neuroectodermal tumor

Background

The tumor microenvironment consists of both physical and chemical factors. Tissue elasticity is one physical factor contributing to the microenvironment of tumor cells. To test the importance of tissue elasticity in cell culture, primitive neuroectodermal tumor (PNET) stem cells were cultured on soft polyacrylamide (PAA) hydrogel plates that mimics the elasticity of brain tissue compared with PNET on standard polystyrene (PS) plates. We report the molecular profiles of PNET grown on either PAA or PS.

Methodology/Principal Findings

A whole-genome microarray profile of transcriptional expression between the two culture conditions was performed as a way to probe effects of substrate on cell behavior in culture. The results showed more genes downregulated on PAA compared to PS. This led us to propose microRNA (miRNA) silencing as a potential mechanism for downregulation. Bioinformatic analysis predicted a greater number of miRNA binding sites from the 3' UTR of downregulated genes and identified as specific miRNA binding sites that were enriched when cells were grown on PAA—this supports the hypothesis that tissue elasticity plays a role in influencing miRNA expression. Thus, Dicer was examined to determine if miRNA processing was affected by tissue elasticity. Dicer genes were downregulated on PAA and had multiple predicted miRNA binding sites in its 3' UTR that matched the miRNA binding sites found enriched on PAA. Many differentially regulated genes were found to be present on PS but downregulated on PAA were mapped onto intron sequences. This suggests expression of alternative polyadenylation sites within intron regions that provide alternative 3' UTRs and alternative miRNA binding sites. This results in tissue specific transcriptional downregulation of mRNA in humans by miRNA. We propose a mechanism, driven by the physical characteristics of the microenvironment by which downregulation of genes occur. We found that tissue elasticity-mediated cytokines (TGFβ2 and TNFα) signaling affect expression of ECM proteins.

Conclusions

Our results suggest that tissue elasticity plays important roles in miRNA expression, which, in turn, regulate tumor growth or tumorigenicity.

SP1-mediated microRNA-520d-5p suppresses tumor growth and metastasis in colorectal cancer by targeting CTHRC1

Recent evidence suggests that miR-520 family has an important role in regulating tumorigenesis and development of various types of solid cancers. However, as one of the most common cancers in the world, there is little known about the underlying regulatory mechanisms of miR-520 in colorectal cancer (CRC). In the present study, we investigated the expression of microRNA-520d-5p (miR-520d-5p) in CRC specimens and then explored its potential role and mechanism in CRC progression. We found that miR-520d-5p was markedly down-regulated in CRC clinical specimens compared with adjacent normal tissues by real-time PCR. Dual-luciferase assays confirmed that miR-520d-5p directly targeting CTHRC1 and SP1 transactivate miR-520d-5p by binding to its upstream promoter region. The biological functional experiments showed that ectopic re-expression of miR-520d-5p suppressed CRC cell proliferation, migration and invasion, whereas the inhibition of miR-520d-5p displayed an inverse effect in vitro and in vivo. Western blot shown that miR-520d-5p abrogated the epithelial-mesenchymal transition by inactivating the phosphorylation of Erk1/2. In conclusion, our findings indicate that miR-520d-5p is significantly down-expressed and involved in CRC progression and metastasis by targeting CTHRC1 and regulated by SP1, which provide new support for miR-520d-5p maybe as a novel anti-onco molecular target for the treatment of CRC in the future.

Integrin α3β1 signaling through MEK/ERK determines alternative polyadenylation of the MMP-9 mRNA transcript in immortalized mouse keratinocytes

Integrin α3β1 is highly expressed in both normal and tumorigenic epidermal keratinocytes where it regulates genes that control cellular function and extracellular matrix remodeling during normal and pathological tissue remodeling processes, including wound healing and development of squamous cell carcinoma (SCC). Previous studies identified a role for α3β1 in immortalized and transformed keratinocytes in the regulation of genes that promote tumorigenesis, invasion, and pro-angiogenic crosstalk to endothelial cells. One such gene, matrix metalloproteinase-9 (MMP-9), is induced by α3β1 through a post-transcriptional mechanism of enhanced mRNA stability. In the current study, we sought to investigate the mechanism through which α3β1 controls MMP-9 mRNA stability. First, we utilized a luciferase reporter assay to show that AU-rich elements (AREs) residing within the 3’-untranslated region (3’-UTR) of the MMP-9 mRNA renders the transcript unstable in a manner that is independent of α3β1. Next, we cloned a truncated variant of the MMP-9 mRNA which is generated through usage of an alternative, upstream polyadenylation signal and lacks the 3’-UTR region containing the destabilizing AREs. Using an RNase protection assay to distinguish “long” (full-length 3’-UTR) and “short” (truncated 3’-UTR) MMP-9 mRNA variants, we demonstrated that the shorter, more stable mRNA that lacks 3’-UTR AREs was preferentially generated in α3β1-expressing keratinocytes compared with α3β1-deficient (i.e., α3-null) keratinocytes. Moreover, we determined that α3β1-dependent alternative polyadenylation was acquired by immortalized keratinocytes, as primary neonatal keratinocytes did not display α3β1-dependent differences in the long and short transcripts. Finally, pharmacological inhibition of the extracellular signal-regulated kinase (ERK)/mitogen-activated protein kinase (MAPK) pathway in α3β1-expressing keratinocytes caused a shift towards long variant expression, while Raf-1-mediated activation of ERK in α3-null keratinocytes dramatically enhanced short variant expression, indicating a role for ERK/MAPK signaling in α3β1-mediated selection of the proximal polyadenylation site. These findings identify a novel mode of integrin α3β1-mediated gene regulation through alternative polyadenylation.

Role of SIRT1 in regulation of epithelial-to-mesenchymal transition in oral squamous cell carcinoma metastasis

BACKGROUND

The epithelial-to-mesenchymal transition (EMT) process results in a loss of cell-cell adhesion, increased cell mobility, and is crucial for enabling the metastasis of cancer cells. Recently, the enzyme SIRT1 has been implicated in a variety of physiological processes; however, its role in regulating oral cancer metastasis and EMT is not fully elucidated. Here, we propose a mechanism by which the enzyme sirtuin1 (SIRT1) regulates the EMT process in oral cancer by deacetylating Smad4 and repressing the effect of TGF-β signaling on matrix metalloproteinase-7 (MMP7).

METHODS

The roles of SIRT1 in tumor cell migration/invasion and metastasis to the lungs were investigated using the Boyden chamber assay and orthotopic injections, respectively. RNA interference was used to knockdown either SIRT1 or Smad4 expression in oral squamous cell carcinoma (OSCC) cell lines. Immunoblotting, zymographic assays, and co-immunoprecipitation were used to examine the effects of SIRT1 overexpression on MMP7 expression and activity, as well as on SIRT1/ Smad4 interaction.

RESULTS

We found that compared with normal human oral keratinocytes (HOKs), SIRT1 was underexpressed in OSCC cells, and also in oral cancer tissues obtained from 14 of 21 OSCC patients compared with expression in their matched normal tissues. Overexpression of SIRT1 inhibited migration of OSCC cells in vitro, as well as their metastasis to the lung in vivo. Furthermore, up-regulation of SIRT1 in metastatic OSCCs significantly inhibited the migration and invasion abilities of OSCC cells, while concomitantly increasing the expression of E-cadherin, and decreasing the expressions of mesenchymal markers. We also identified Smad4, a TGF-β-activated transcription factor, as a direct target protein for SIRT1. Overexpression of SIRT1 in OSCC cells led to decreased levels of acetylated Smad4, and inhibition of TGF-β-induced signaling. By associating and deacetylating Smad4, SIRT1 enzyme can influence MMP7 expression, MMP enzyme activity, and consequently, cell migration, invasion, and tumor metastasis in OSCCs.

CONCLUSIONS

These findings provide a valuable insight into the potential role of the SIRT1 enzyme in regulating cell migration and invasion in oral squamous cell carcinoma. Our findings suggest the SIRT1/Smad4/MMP7 pathway as a target for oral cancer driven by EMT.

Regulation of cancer metastasis by cell-free miRNAs

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

Interferon receptor signaling in malignancy: a network of cellular pathways defining biological outcomes

IFNs are cytokines with important antiproliferative activity and exhibit key roles in immune surveillance against malignancies. Early work initiated over three decades ago led to the discovery of IFN receptor activated Jak-Stat pathways and provided important insights into mechanisms for transcriptional activation of IFN-stimulated genes (ISG) that mediate IFN biologic responses. Since then, additional evidence has established critical roles for other receptor-activated signaling pathways in the induction of IFN activities. These include MAPK pathways, mTOR cascades, and PKC pathways. In addition, specific miRNAs appear to play a significant role in the regulation of IFN signaling responses. This review focuses on the emerging evidence for a model in which IFNs share signaling elements and pathways with growth factors and tumorigenic signals but engage them in a distinctive manner to mediate antiproliferative and antiviral responses.

MicroRNAs in soft tissue sarcomas: overview of the accumulating evidence and importance as novel biomarkers

Sarcomas are distinctly heterogeneous tumors and a variety of subtypes have been described. Although several diagnostic explorations in the past three decades, such as identification of chromosomal translocation, have greatly improved the diagnosis of soft tissue sarcomas, the unsolved issues, including the limited useful biomarkers, remain. Emerging reports on miRNAs in soft tissue sarcomas have provided clues to solving these problems. Evidence of circulating miRNAs in patients with soft tissue sarcomas and healthy individuals has been accumulated and is accelerating their potential to develop into clinical applications. Moreover, miRNAs that function as novel prognostic factors have been identified, thereby facilitating their use in miRNA-targeted therapy. In this review, we provide an overview of the current knowledge on miRNA deregulation in soft tissue sarcomas, and discuss their potential as novel biomarkers and therapeutics.

Sirt1, a negative regulator of matrix metalloproteinase-9 in diabetic retinopathy

PURPOSE

In the pathogenesis of diabetic retinopathy, matrix metalloproteinase (MMP)-9 damages retinal mitochondria, activating the apoptotic machinery. Transcription of MMP-9 is regulated by nuclear factor kappa B (NF-κB), and the activation of NF-κB is modulated by the acetylation of its p65 subunit. Sirtuin 1 (Sirt1), a deacetylase, plays an important role in the acetylation-deacetylation of p65. The goal of this study is to investigate the role of Sirt1 in the activation of MMP-9 in diabetic retinopathy.

METHODS

The effect of hyperglycemia and Sirt1 activator, resveratrol, on acetylation of p65 and its binding at MMP-9 promoter-and mitochondrial damage and apoptosis-was assessed in the retinal endothelial cells. Role of oxidative stress in the regulation of Sirt1 was evaluated in the cells incubated in H2O2. The results were confirmed in the retina from diabetic mice with Sod2 or MMP-9 gene manipulated.

RESULTS

High glucose decreased Sirt1 activity and increased p65 acetylation, and resveratrol prevented increase in p65 acetylation, binding of p65 at MMP-9 promoter and MMP-9 activation, mitochondria damage, and cell apoptosis. While Sirt1 was decreased by H2O2, MMP-9 was significantly increased. Retina from wild-type diabetic mice presented similar decrease in Sirt1, and diabetic mice with Sod2 overexpression or MMP-9 deletion had normal retinal Sirt1. Retinal microvasculature from human donors with established diabetic retinopathy also had decreased Sirt1.

CONCLUSIONS

Thus, in diabetes, increase in oxidative stress inhibits Sirt1 and p65 is hyperacetylated, increasing the binding of p65 at MMP-9 promoter. Prevention of Sirt1 inhibition, via modulating acetylation of p65, should protect activation of MMP-9 and inhibit the development of diabetic retinopathy.

MicroRNA-520c-3p inhibits hepatocellular carcinoma cell proliferation and invasion through induction of cell apoptosis by targeting glypican-3

AIM

Glypican-3 (GPC3) is a membrane-associated heparan sulfate proteoglycan involved in regulation of cell proliferation, cell survival, cell migration and differentiation process. MicroRNAs (miRNAs) are single-stranded, non-coding functional RNAs that are important in many biological processes. GPC3 and miRNAs have been found to play essential roles in the development and progression of hepatocellular carcinoma (HCC). However, little information about the relationship between GPC3 and miRNAs is available nowadays. Therefore, this study aims to examine the relationship between GPC3 and miRNAs.

METHODS

Dual-luciferase reporter assay was used to validate the direct target of GPC3. Fluorescence quantitative PCR and Western blotting were used to examined the gene expression at mRNA and protein levels. Cell apoptosis was evaluated by flow cytometric analysis and Annexin V-FITC staining. Invasion of cells was evaluated by Transwell matrigel assay.

RESULTS

The results showed that miR-520c-3p could specifically target GPC3 in HCC cells. GPC3 protein levels decreased with unchanged transcription efficiency after miRNA transfection, and there was negative correlation of miR-520c-3p expression in HCC in relate to GPC3 protein levels. Moreover, miR-520c-3p not only induced HCC cell apoptosis, but also inhibited the growth and invasion of the cells. Interestingly, overexpression of GPC3 could effectively reverse apoptosis induced by miR-520c-3p transfection in HCC.

CONCLUSIONS

Taken together, these results supported that miR-520c-3p may decrease GPC3 protein levels to inhibit proliferation of HCC cells. Therefore, GPC3 could be a new target for genetic diagnosis and treatment of HCC.

Down-regulation of eIF4GII by miR-520c-3p represses diffuse large B cell lymphoma development

Deregulation of the translational machinery is emerging as a critical contributor to cancer development. The contribution of microRNAs in translational gene control has been established however; the role of microRNAs in disrupting the cap-dependent translation regulation complex has not been previously described. Here, we established that elevated miR-520c-3p represses global translation, cell proliferation and initiates premature senescence in HeLa and DLBCL cells. Moreover, we demonstrate that miR-520c-3p directly targets translation initiation factor, eIF4GII mRNA and negatively regulates eIF4GII protein synthesis. miR-520c-3p overexpression diminishes cells colony formation and reduces tumor growth in a human xenograft mouse model. Consequently, downregulation of eIF4GII by siRNA decreases translation, cell proliferation and ability to form colonies, as well as induces cellular senescence. In vitro and in vivo findings were further validated in patient samples; DLBCL primary cells demonstrated low miR-520c-3p levels with reciprocally up-regulated eIF4GII protein expression. Our results provide evidence that the tumor suppressor effect of miR-520c-3p is mediated through repression of translation while inducing senescence and that eIF4GII is a key effector of this anti-tumor activity.

Control of gene expression on the translational level is critical for proper function of major cellular processes and deregulation of translation can promote cellular transformation. Emerging actors in this post-transcriptional gene regulation are small non-coding RNAs referred to as microRNAs (miRNAs). We established that miR-520c-3p represses tumor growth through the repression of eIF4GII, a major structural component of the translation initiation complex. Since translation of most cellular mRNAs is primarily regulated at the level of initiation, this node is becoming a potential target for therapeutic intervention. Identified in this study, tumor suppressor function of miR-520c-3p is mediated through the inhibition of translational factor eIF4GII, resulting in the repression of global translational machinery and induction of senescence in tumor cells. While aging and senescence has been shown to be associated with reduced translation the linkage between translational deregulation and senescence in malignant cells has not been previously described. Lending further clinical significance to our findings, we were able to demonstrate that primary DLBCL samples had elevated levels of eIF4GII while having reciprocally low miR-520c-3p expression.

Placenta-specific miRNA (miR-512-3p) targets PPP3R1 encoding the calcineurin B regulatory subunit in BeWo cells

AIM

The microRNAs (miRNAs) derived from the chromosome 19 miRNA cluster (C19MC) are exclusively expressed in the human placenta, but the origin and functions of C19MC miRNAs are not fully understood. The purpose of this study was to elucidate which cells express C19MC miRNAs in chorionic villi and identify their miRNA targets.

METHODS

A combination of laser microdissection (LMD) and real-time polymerase chain reaction (PCR) to examine the localization of five C19MC miRNAs (i.e. miR-512-3p, miR-518b, miR-520a, miR-524 and miR-1323) in the human placenta was performed. Furthermore, to identify miR-512-3p-target genes, we analyzed gene expression profiles of the trophoblast cell line BeWo using a DNA microarray. Predicted target genes were validated by real-time PCR, western blotting, and 3'-untranslated region reporter assay.

RESULTS

By LMD and subsequent PCR analysis, five C19MC miRNAs examined in this study were predominantly expressed in villous trophoblast cells; little expression, if any, was observed in villous stroma cells or fetal endothelial cells. Microarray data showed that 334 genes were downregulated in BeWo cells treated with Pre-miR-512-3p (mature miR-512-3p mimic). We found six candidate target genes of miR-512-3p using DNA microarray data and target prediction software. Furthermore, we revealed that protein phosphatase 3, regulatory subunit B, alpha (PPP3R1), one of the six genes, was a miR-512-3p target using an in vitro experimental validation system.

CONCLUSION

These data suggest that miR-512-3p participates in human trophoblast function[s] by targeting PPP3R1, encoding a regulatory subunit of calcineurin.

Regulation of SIRT1 by oxidative stress-responsive miRNAs and a systematic approach to identify its role in the endothelium

SIGNIFICANCE

Oxidative stress is a common denominator of various risk factors contributing to endothelial dysfunction and vascular diseases. Accumulated evidence suggests that sirtuin 1 (SIRT1) expression and/or activity is impaired by supraphysiological levels of oxidative stress, which in turn disrupts endothelial homeostasis.

RECENT ADVANCES

Several microRNAs (miRNAs) are induced by oxidative stress and termed as oxidative stress-responsive miRNAs. They may play a role linking the imbalanced redox state with dysregulated SIRT1.

CRITICAL ISSUES

This review summarizes recent findings on oxidative stress-responsive miRNAs and their involvement in SIRT1 regulation. Because of the unique characteristics of miRNAs, research in this new area requires an integrative approach that combines bioinformatics and experimental validation. Thus, a research strategy is discussed to identify the SIRT1-regulating miRNAs under oxidative stress and their functional outcomes in relation to endothelial dysfunction. Additionally, the miRNAs implicated in vascular diseases such as atherosclerosis and abdominal aortic aneurysms are discussed along with the translational potential and challenges of using miRNAs and its analogs as therapeutic agents.

FUTURE DIRECTIONS

Although at its infancy, research on oxidative stress-responsive miRNAs and their regulation of SIRT1 may provide new insights in understanding vascular disorders. Moreover, systematic approaches integrating in silico, in vitro, and in vivo observations can be useful tools in revealing the pathways modulating endothelial biology.

SIRT1 is highly expressed in brain metastasis tissues of non-small cell lung cancer (NSCLC) and in positive regulation of NSCLC cell migration

Brain metastases are a frequent and ongoing major complication of non-small cell lung cancer (NSCLC). To deepen our understanding to the underlying mechanisms by which NSCLC cells metastasize to brain and hence to improve the therapy, a high throughput RNAi screening with shRNA library of 153 epigenetic genes was subjected to A549, a NSCLC cell line with high migration ability, to examine the effects of these genes on cell migration by wound-healing assay. The screening results showed that knockdown of 2 genes (KDM5B and SIRT1) dramatically and specifically inhibits A549 migration but not affects the proliferation, which was subsequently confirmed through transwell migration assay. Furthermore, SIRT1 is found to be highly expressed in brain metastasis tissues of NSCLC, compared to the NSCLC tissues, suggesting that SIRT1 may play roles in brain metastasis of NSCLC. The relationship between SIRT1 expression and cell migration ability was further investigated in three NSCLC cell lines and the result indicated that SIRT1 expression is tightly correlated with cell migration ability. Collectively, our work provides potential biomarker and therapeutic target for brain metastasis of NSCLC.

MicroRNAs: regulators of cancer metastasis and epithelial-mesenchymal transition (EMT)

Tumor metastasis is the main cause of death in patients with solid tumors. The epithelial-mesenchymal transition (EMT) process, in which epithelial cells are converted into mesenchymal cells, is frequently activated during cancer invasion and metastasis. MicroRNAs (miRNAs) are small, non-coding RNAs that provide widespread expressional control by repressing mRNA translation and inducing mRNA degradation. The fundamental roles of miRNAs in tumor growth and metastasis have been increasingly well recognized. A growing number of miRNAs are reported to regulate tumor invasion/metastasis through EMT-related and/or non-EMT- related mechanisms. In this review, we discuss the functional role and molecular mechanism of miRNAs in regulating cancer metastasis and EMT.

Epigenetic regulation of mmp-9 gene expression

Matrix metalloproteinase 9 (MMP-9) is one of the most studied enzymes in cancer. MMP-9 can cleave proteins of the extracellular matrix and a large number of receptors and growth factors. Accordingly, its expression must be tightly regulated to avoid excessive enzymatic activity, which is associated with disease progression. Although we know that epigenetic mechanisms play a central role in controlling mmp-9 gene expression, predicting how epigenetic drugs could be used to suppress mmp-9 gene expression is not trivial because epigenetic drugs also regulate the expression of key proteins that can tip the balance towards activation or suppression of MMP-9. Here, we review how our understanding of the biology and expression of MMP-9 could be exploited to augment clinical benefits, most notably in terms of the prevention and management of degenerative diseases and cancer.

Role of microRNA-mediated MMP regulation in the treatment and diagnosis of malignant tumors

Matrix metalloproteinases (MMPs) play important roles in tumor cell proliferation and apoptosis and contribute to tumor growth, angiogenesis, migration, and invasion primarily via extracellular matrix (ECM) degradation and/or the activation of pre-pro-growth factors. Recently, there has been considerable interest in the posttranscriptional regulation of MMPs via microRNAs (miRs). In this review, we highlight the complicated interactive network comprised of different MMPs and their regulating microRNAs, as well as the ways in which these interactions influence cancer development, including tumor angiogenesis, growth, invasion, and metastasis. Based on the conclusive roles that microRNAs play in the regulation of MMPs during cancer progression, we discuss the potential use of microRNA-mediated MMP regulation in the diagnosis and treatment of tumors from the clinical perspective. In particular, microRNA-mediated MMP regulation may lead to the development of promising new MMP inhibitors that target MMPs more selectively, and this approach may also target multiple molecules in a network, leading to the efficient regulation of distinct biological processes relevant to malignant tumors. A thorough understanding of the mechanisms underlying microRNA-mediated MMP regulation during tumor progression will help to provide new insights into the diagnosis and treatment of malignant tumors.

CHO microRNA engineering is growing up: recent successes and future challenges

microRNAs with their ability to regulate complex pathways that control cellular behavior and phenotype have been proposed as potential targets for cell engineering in the context of optimization of biopharmaceutical production cell lines, specifically of Chinese Hamster Ovary cells. However, until recently, research was limited by a lack of genomic sequence information on this industrially important cell line. With the publication of the genomic sequence and other relevant data sets for CHO cells since 2011, the doors have been opened for an improved understanding of CHO cell physiology and for the development of the necessary tools for novel engineering strategies. In the present review we discuss both knowledge on the regulatory mechanisms of microRNAs obtained from other biological models and proof of concepts already performed on CHO cells, thus providing an outlook of potential applications of microRNA engineering in production cell lines.

A novel epigenetic CREB-miR-373 axis mediates ZIP4-induced pancreatic cancer growth

Changes in the intracellular levels of the essential micronutrient zinc have been implicated in multiple diseases including pancreatic cancer; however, the molecular mechanism is poorly understood. Here, we report a novel mechanism where increased zinc mediated by the zinc importer ZIP4 transcriptionally induces miR-373 in pancreatic cancer to promote tumour growth. Reporter, expression and chromatin immunoprecipitation assays demonstrate that ZIP4 activates the zinc-dependent transcription factor CREB and requires this transcription factor to increase miR-373 expression through the regulation of its promoter. miR-373 induction is necessary for efficient ZIP4-dependent enhancement of cell proliferation, invasion, and tumour growth. Further analysis of miR-373 in vivo oncogenic function reveals that it is mediated through its negative regulation of TP53INP1, LATS2 and CD44. These results define a novel ZIP4-CREB-miR-373 signalling axis promoting pancreatic cancer growth, providing mechanistic insights explaining in part how a zinc transporter functions in cancer cells and may have broader implications as inappropriate regulation of intracellular zinc levels plays an important role in many other diseases.

MicroRNAs and tumor vasculature normalization: impact on anti-tumor immune response

Inefficient immune response is a major glitch during tumor growth and progression. Chaotic and leaky blood vessels created in the process of angiogenesis allow tumor cells to escape and extricate anti-cancer immunity. Proangiogenic characteristics of hypoxic tumor microenvironment maintained by low oxygen tension attract endothelial progenitor cells, drive expansion of cancer stem cells, and deviantly differentiate monocyte descendants. Such cellular milieu further boosts immune tolerance and eventually appoint immunity for cancer advantage. Blood vessel normalization strategies that equilibrate oxygen levels within tumor and fix abnormal vasculature bring exciting promises to future anticancer therapies especially when combined with conventional chemotherapy. Recently, a new group of microRNAs (miRs) engaged in angiogenesis, called angiomiRs and hypoxamiRs, emerged as new therapeutic targets in cancer. Some of those miRs were found to efficiently regulate cancer immunity and their dysregulation efficiently programs aberrant angiogenesis and cancer metastasis. The present review highlights new findings in the field of miRs proficiency to normalize aberrant angiogenesis and to restore anti-tumor immune responses.