Down-regulation of MicroRNAs (MiRs) 203, 887, 3619 and 182 Prevents Vimentin-triggered, Phospholipase D (PLD)-mediated Cancer Cell Invasion

Stratification of acute myocardial and endothelial cell injury, salvage index and final infarct size by systematic microRNA profiling in acute ST-elevation myocardial infarction

AIM

Acute injury and subsequent remodelling responses to ST-segment elevation myocardial infarction (STEMI) are major determinants of clinical outcome. Current imaging and plasma biomarkers provide delayed readouts of myocardial injury and recovery. Here, we sought to systematically characterize all microRNAs (miRs) released during the acute phase of STEMI and relate miR release to magnetic resonance imaging (MRI) findings to predict acute and late responses to STEMI, from a single early blood sample.

METHODS AND RESULTS

miRs were quantified in blood samples obtained from patients after primary PCI (PPCI) for STEMI. Cardiac MRI (cMRI) was performed to quantify myocardial edema, infarct size and salvage index. Regression models were constructed to predict these outcomes measures, which were then tested with a validation cohort. Transcoronary miR release was quantified from paired measurements of coronary artery and coronary sinus samples. A cell culture model was used to identify endothelial cell-derived miRs.A total of 72 patients undergoing PPCI for acute STEMI underwent miR analysis and cMRI. About >200 miRs were detectable in plasma after STEMI, from which 128 miRs were selected for quantification in all patients. Known myocardial miRs demonstrated a linear correlation with troponin release, and these increased across the transcoronary gradient. We identified novel miRs associated with microvascular injury and myocardial salvage. Regression models were constructed using a training cohort, then tested in a validation cohort, and predicted myocardial oedema, infarct size and salvage index.

CONCLUSION

Analysis of miR release after STEMI identifies biomarkers that predict both acute and late outcomes after STEMI. A novel miR-based biomarker score enables the estimation of area at risk, late infarct size and salvage index from a single blood sample 6 hours after PPCI, providing a simple and rapid alternative to serial cMRI characterization of STEMI outcome.

Rutin Promotes Pancreatic Cancer Cell Apoptosis by Upregulating miRNA-877-3p Expression

(1) Background: pancreatic cancer is one of the most serious cancers due to its rapid and inevitable fatality, which has been proved very difficult to treat, compared with many other common cancers. Thus, developing an effective therapeutic strategy, especially searching for potential drugs, is the focus of current research. The exact mechanism of rutin in pancreatic cancer remains unknown. (2) Method: three pancreatic cancer cell lines were used to study the anti-pancreatic cancer effect of rutin. The potent anti-proliferative, anti-migration and pro-apoptotic properties of rutin were uncovered by cell viability, a wound-healing migration assay, and a cell apoptosis assay. High-throughput sequencing technology was used to detect the change of miRNAs expression. Immunoblotting analysis was used to detect the expression of apoptotic proteins. (3) Results: CCK-8 and EDU assays revealed that rutin significantly inhibited pancreatic cancer cells’ proliferation (p < 0.05). A wound-healing assay showed that rutin significantly suppressed pancreatic cancer cells’ migration (p < 0.05). A flow cytometric assay showed that rutin could promote pancreatic cancer cells’ apoptosis. Intriguingly, rutin significantly upregulated miR-877-3p expression to repress the transcription of Bcl-2 and to induce pancreatic cancer cell apoptosis. Accordingly, rutin and miR-877-3p mimics could promote apoptotic protein expression. (4) Conclusions: our findings indicate that rutin plays an important role in anti-pancreatic cancer effects through a rutin-miR-877-3p-Bcl-2 axis and suggests a potential therapeutic strategy for pancreatic cancer.

The Epithelial-Mesenchymal Transition at the Crossroads between Metabolism and Tumor Progression

The transition between epithelial and mesenchymal phenotype is emerging as a key determinant of tumor cell invasion and metastasis. It is a plastic process in which epithelial cells first acquire the ability to invade the extracellular matrix and migrate into the bloodstream via transdifferentiation into mesenchymal cells, a phenomenon known as epithelial–mesenchymal transition (EMT), and then reacquire the epithelial phenotype, the reverse process called mesenchymal–epithelial transition (MET), to colonize a new organ. During all metastatic stages, metabolic changes, which give cancer cells the ability to adapt to increased energy demand and to withstand a hostile new environment, are also important determinants of successful cancer progression. In this review, we describe the complex interaction between EMT and metabolism during tumor progression. First, we outline the main connections between the two processes, with particular emphasis on the role of cancer stem cells and LncRNAs. Then, we focus on some specific cancers, such as breast, lung, and thyroid cancer.

Research Progress on the Role of Intermediate Filament Vimentin in Atherosclerosis

The cytoskeleton is a biopolymer network composed of intermediate filaments, actin, and microtubules, which is the main mechanical structure of cells. Vimentin is an intermediate filament protein that regulates the mechanical and contractile properties of cells, thereby reflecting their mechanical properties. In recent years, the "nonmechanical function" of vimentin inside and outside of cells has attracted extensive attention. The content of vimentin in atherosclerotic plaques is increased, and the serum secretion of vimentin in patients with coronary heart disease is remarkably increased. In this review, the mechanistic and nonmechanistic roles of vimentin in atherosclerosis progression were summarized on the basis of current studies.

Nano-Graphene Oxide-Promoted Epithelial-Mesenchymal Transition of Human Retinal Pigment Epithelial Cells through Regulation of Phospholipase D Signaling

Nano-graphene oxide (Nano-GO) is an extensively studied multifunctional carbon nanomaterial with attractive applications in biomedicine and biotechnology. However, few studies have been conducted to assess the epithelial-to-mesenchymal transition (EMT) in the retinal pigment epithelium (RPE). We aimed to determine whether Nano-GO induces EMT by regulating phospholipase D (PLD) signaling in human RPE (ARPE-19) cells. The physicochemical characterization of Nano-GO was performed using a Zetasizer, X-ray diffraction, Fourier-transform infrared spectroscopy, and transmission electron microscopy. RPE cell viability assays were performed, and the migratory effects of RPE cells were evaluated. RPE cell collagen gel contraction was also determined. Intracellular reactive oxygen species (ROS) levels were determined by fluorescence microscopy and flow cytometry. Immunofluorescence staining and western blot analysis were used to detect EMT-related protein expression. Phospholipase D (PLD) enzymatic activities were also measured. Nano-GO significantly enhanced the scratch-healing ability of RPE cells, indicating that the RPE cell migration ability was increased. Following Nano-GO treatment, the RPE cell penetration of the chamber was significantly promoted, suggesting that the migratory ability was strengthened. We also observed collagen gel contraction and the generation of intracellular ROS in RPE cells. The results showed that Nano-GO induced collagen gel contraction and intracellular ROS production in RPE cells. Moreover, immunofluorescence staining and western blot analysis revealed that Nano-GO significantly regulated key molecules of EMT, including epithelial-cadherin, neural-cadherin, α-smooth muscle actin, vimentin, and matrix metalloproteinases (MMP-2 and MMP-9). Interestingly, Nano-GO-induced RPE cell migration and intracellular ROS production were abrogated in PLD-knockdown RPE cells, indicating that PLD activation played a crucial role in the Nano-GO-induced RPE EMT process. We demonstrate for the first time that Nano-GO promotes RPE cell migration through PLD-mediated ROS production. We provide preliminary evidence to support the hypothesis that Nano-GO has adverse health effects related to RPE damage.

Regulation of breast cancer metastasis signaling by miRNAs

Despite the decline in death rate from breast cancer and recent advances in targeted therapies and combinations for the treatment of metastatic disease, metastatic breast cancer remains the second leading cause of cancer-associated death in U.S. women. The invasion-metastasis cascade involves a number of steps and multitudes of proteins and signaling molecules. The pathways include invasion, intravasation, circulation, extravasation, infiltration into a distant site to form a metastatic niche, and micrometastasis formation in a new environment. Each of these processes is regulated by changes in gene expression. Noncoding RNAs including microRNAs (miRNAs) are involved in breast cancer tumorigenesis, progression, and metastasis by post-transcriptional regulation of target gene expression. miRNAs can stimulate oncogenesis (oncomiRs), inhibit tumor growth (tumor suppressors or miRsupps), and regulate gene targets in metastasis (metastamiRs). The goal of this review is to summarize some of the key miRNAs that regulate genes and pathways involved in metastatic breast cancer with an emphasis on estrogen receptor α (ERα+) breast cancer. We reviewed the identity, regulation, human breast tumor expression, and reported prognostic significance of miRNAs that have been documented to directly target key genes in pathways, including epithelial-to-mesenchymal transition (EMT) contributing to the metastatic cascade. We critically evaluated the evidence for metastamiRs and their targets and miRNA regulation of metastasis suppressor genes in breast cancer progression and metastasis. It is clear that our understanding of miRNA regulation of targets in metastasis is incomplete.

MiR-122-5p and miR-326-3p promote cadmium-induced NRK-52E cell apoptosis by downregulating PLD1

Cadmium is a toxic heavy metal distributed broadly in the environment and manufactory industry. Long-term exposure to cadmium, considered as a risk for kidney injury, leads to chronic kidney disease eventually. Phospholipase D1 (PLD1) promotes cell proliferation and inhibits apoptosis, and might be involved in cadmium-induced kidney injury. In this study, we used miRNA microarray assays and bioinformatics analysis to identify miRNAs, which may regulate PLD1 expression and exert an impact on cadmium-induced kidney injury. MiR-122-5p and miR-326-3p，selected as candidates, were explored for their regulatory functions in kidney injury, using NRK-52E cells. Both of these two miRNAs exhibited higher expression in kidneys of SD rats after exposure to cadmium for 6 weeks. Cadmium treatment also increased miR-122-5p and miR-326-3p and decreased PLD1 in NRK-52E cells. Both of miR-122-5p and miR-326-3p could downregulate PLD1 expression through targeting its 3'UTR and enhance cadmium-induced apoptosis, while inhibiting either of these two miRNAs could reverse such effects. In conclusion, our results suggest that miR-122-5p and miR-326-3p might enhance cadmium-induced NRK-52E cell apoptosis through downregulating PLD1 expression.

D-series Resolvins activate Phospholipase D in phagocytes during inflammation and resolution

A successful acute inflammatory response results in the elimination of infectious agents by neutrophils and monocytes, followed by resolution and repair through tissue-resident and recruited macrophages. Resolvins (D-series and E-series) are pro-resolving lipid mediators involved in resolution and tissue repair, whose intracellular signaling remains of interest. Here, we report that D-series resolvins (RvD1- RvD5) activate phospholipase D (PLD), a ubiquitously expressed membrane lipase enzyme activity in modulating phagocyte functions. The mechanism for PLD-mediated actions of Resolvin-D5 (RvD5) in polarizing macrophages (M1-like toward M2-like) was found to be two-pronged: (a) RvD5 inhibits post-transcriptional modifications, by miRs and 3'exonucleases that process PLD2 mRNA, thus increasing PLD2 expression and activity; and (b) RvD5 enhances PLD2-S6Kinase signaling required for membrane expansion and efferocytosis. In an in vivo model of second organ reflow injury, we found that RvD5 did not reduce lung neutrophil myeloperoxidase levels in PLD2^-/- mice compared to WT and PLD1^-/- mice, confirming a novel role of PLD2 as the isoform in RvD5-mediated resolution processes. These results demonstrate that RvD5-PLD2 are attractive targets for therapeutic interventions in vascular inflammation such as ischemia-reperfusion injury and cardiovascular diseases.

Phospholipase D1 and D2 Synergistically Regulate Thrombus Formation

Previously, we reported that phospholipase D1 (PLD1) and PLD2 inhibition by selective PLD1 and PLD2 inhibitors could prevent platelet aggregation in humans, but not in mice. Moreover, only the PLD1 inhibitor, but not PLD2 inhibitor, could effectively prevent thrombus formation in mice, indicating that PLD might play different roles in platelet function in humans and mice. Although PLD1 and PLD2 were reported to be implicated in thrombotic events, the role of PLD in mice remains not completely clear. Here, we investigated the role of PLD1 and PLD2 in acute pulmonary thrombosis and transient middle cerebral artery occlusion-induced brain injury in mice. The data revealed that inhibition of PLD1, but not of PLD2, could partially prevent pulmonary thrombosis-induced death. Moreover, concurrent PLD1 and PLD2 inhibition could considerably increase survival rate. Likewise, inhibition of PLD1, but not PLD2, partially improved ischemic stroke and concurrent inhibition of PLD1, and PLD2 exhibited a relatively better protection against ischemic stroke, as evidenced by the infarct size, brain edema, modified neurological severity score, rotarod test, and the open field test. In conclusion, PLD1 might play a more important role than PLD2, and both PLD1 and PLD2 could act synergistically or have partially redundant functions in regulating thrombosis-relevant events.

Long non-coding RNA SNHG3, induced by IL-6/STAT3 transactivation, promotes stem cell-like properties of gastric cancer cells by regulating the miR-3619-5p/ARL2 axis

BACKGROUND

Chemotherapy is, next to surgery and radiotherapy, the mainstay regimen for the clinical management of gastric cancer. This therapy is, however, heavily compromised by the acquisition of resistance. Here, we aimed to clarify the potential involvement of long non-coding RNA SNGH3 in the acquisition of cisplatin resistance and stemness in gastric cancer.

METHODS

Cell viability and proliferation were measured using Cell Counting Kit-8 and colony formation assays, respectively. Stem cell-like cell growth was evaluated using a mammosphere formation assay. RNA levels of SNHG2, OCT-4, SOX-2, CD44, miR-3619-5p and ARL2 were determined using qRT-PCR, whereas protein levels of OCT-4, SOX-2, CD44, ARL2, STAT3 and pSTAT3 were determined using Western blotting. Dual luciferase reporter assays were employed to interrogate regulatory interactions between STAT3, SNHG3, miR-3619-5p and ARL2, respectively. Direct binding of STAT3 to the SNHG3 promoter was investigated using a chromatin immunoprecipitation assay.

RESULTS

We found that IL-6 triggered stem cell-like properties in cisplatin-treated gastric cancer cells and activated STAT3, which in turn transcriptionally regulated SNHG3 expression. SNHG3 expression up-regulation positively correlated with cisplatin resistance and stemness of gastric cancer cells, while SNHG3 down-regulation inhibited stem cell-like properties. In addition, we found that SNHG3 up-regulated ARL2 expression through sponging miR-3619-5p, which predominantly mediated the oncogenic properties of SNHG3 in this disease.

CONCLUSIONS

Our data indicate an involvement of aberrant SNHG3 over-expression in the acquisition of both cisplatin resistance and stemness of gastric cancer cells, and of the IL-6/STAT3/SNHG3/miR-3619-5p/ARL2 signaling cascade in the oncogenic properties of SNHG3.

MiR-887 Promotes the Progression of Hepatocellular Carcinoma via Targeting VHL

Background:

MiR-887 has been proved to promote the tumorigenesis in diverse cancers, but its function and downstream mechanism in hepatocellular carcinoma remain obscure.

Methods:

Quantitative real-time polymerase chain reaction was performed to detect the expression levels of miR-887 in hepatocellular carcinoma tissues and cell lines. MiR-887 mimics and miR-887 inhibitor were transfected into Huh7 and MHCC97H to establish miR-887 overexpression or inhibition models. Cell Counting Kit-8 and colony formation experiment were conducted to monitor cell proliferation. Subcutaneous xenotransplanted tumor model and tail vein injection model in mice were also established to further verify the effect of miR-887 on hepatocellular carcinoma in vivo. The targeting relationship between miR-887 and von Hippel-Lindau tumor suppressor (VHL) was determined by quantitative real-time polymerase chain reaction, Western blot, and luciferase reporter gene assay.

Results:

miR-887 expression in hepatocellular carcinoma tissues was significantly upregulated. Compared with the control cells, the proliferation and metastasis of cancer cells were enhanced by miR-887 mimics and suppressed by miR-887 inhibitor. Compared with control mice, the volume and weight of subcutaneous tumors of mice in the miR-887 mimics group were significantly elevated, and the significant increase was found in the occurrence of lung metastasis. Moreover, bioinformatics tools showed that miR-887 and VHL had 2 binding sites. Luciferase activity assay demonstrated that miR-887 can inhibit the luciferase activity of VHL, and miR-887 mimics could reduce the expressions of VHL at both messenger RNA and protein levels to increase hypoxia-inducible factor α expression.

Conclusion:

The upregulation of miR-887 could facilitate the proliferation and metastasis of hepatocellular carcinoma cells via targeting VHL.

MicroRNA analysis of NCI-60 human cancer cells indicates that miR-720 and miR-887 are potential therapeutic biomarkers for breast cancer

MicroRNAs (miRNAs) play a vital role in many biological processes, including cell growth, differentiation, apoptosis, development, differentiation, and carcinogenesis. Since miRNAs might play a part in cancer initiation and progression, they comprise an original class of promising diagnostic and prognostic molecular markers. In order to systematically understand the regulation of miRNA expression in cancers, the current study analyzed the miRNA expression profile in NCI-60 human cancer cell lines. Over 300 miRNAs exhibited unique expression profiles in cell lines derived from the same lineage. This study identified 9 lineage-specific miRNA expression patterns. Moreover, results indicated that miR-720 and miR-887 are expressed at relatively high levels in breast cancer cell lines compared to other types of cancer. Ultimately, matching NCI-60 drug response data to miR-720 and miR-887 expression profiles revealed that several FDA-approved drugs were inversely related to miR-720 and miR-887. Furthermore, the anti-cancer effect of perifosine was significantly enhanced by inhibiting miR-720 and decreased by miR-720 precursor treatment in breast cancer cell lines. 5-Fu treatment was enhanced by inhibiting miR-887 and decreased by miR-887 precursor treatment. The current results offer insight into the relationship between miRNA expression and their lineage types, and the approach used here represents a potential cancer therapy with the help of miRNAs.

Serum exosomal miRNA as biomarkers for Retinoblastoma

Retinoblastoma (RB) is a childhood eye tumor, caused by RB1 mutation. Though diagnosing RB is easier, prognosticating RB is limited to examining the patient under anesthesia and imaging technique. The aim of the study is to find exosomal miRNA biomarkers to prognosticate RB. Exosomes were isolated from one control - MIO-M1 and two RB cell lines - WERI-Rb-1 and NCC-RbC-51. Small RNA sequencing was performed on exosomal miRNA isolated from the three cell lines. miRNAs specific to each cell line were shortlisted. A total of 243, 606 and 400 miRNAs were identified in MIO-M1, WERI-Rb-1 and NCC-RbC-51 cell lines respectively. Nine miRNAs were shortlisted based on adjusted p value and literature, MIO-M1 specific (n = 1), WERI-RB-1 specific (n = 2), NCC-RbC-51 specific (n = 2) and miRNAs common to both RB cell lines (n = 4) were chosen. Validation was done using specific Taqman miRNA assays.miRNA validation was carried out on cell lines, cell line derived exosomes, primary RB tissues and exosomes isolated from serum of the RB patients. Validation of the miRNAs in cell lines and exosomes derived from the cell lines, confirmed the sequencing data. However, only 2 miRNAs - hsa-miR-301b-3p and hsa-miR-216b-5p were upregulated in the primary RB tissues. None of the miRNAs had significant expression in the serum exosomes of RB patients. Therefore, serum exosomal miRNA may not be ideal for prognosticating RB.Further research on other body fluids like CSF and vitreous could serve as potential source for biomarkers for prognosticating RB.

MiR-887-3p Negatively Regulates STARD13 and Promotes Pancreatic Cancer Progression

Purpose

STARD13 is regulated by various miRNAs. However, there are relatively few reports describing the relationship between miRNAs and STARD13 in pancreatic cancer. Therefore, the aim of this study was to explore the relationship between miRNA and STARD13 in pancreatic cancer.

Patients and Methods

By analyzing the data from Gene Expression Omnibus (GEO) database, the relationship between STARD13 expression and pancreatic cancer was explored. Then, through sequence alignment, the sequence complementary to miR-887-3p in the 3ʹUTR of STARD13 mRNA was found, mutated and cloned. Dual-luciferase reporter assay was used to test the relationship between STARD13 and miR-887-3p. Pancreatic cancer tumor tissue and its adjacent tissues collected, and the expression of STARD13 and miR-887-3p in pancreatic cancer tissues was analyzed by RT-qPCR. After, miR-887-3p and its inhibitor were transfected into PANC-1 cells to further confirm the regulatory relationship between miR-887-3 and STARD13 by RT-qPCR, and CCK-8, colony formation assays, cell cycle analysis, apoptosis detection and transwell analysis were used to detect changes of proliferation, apoptosis, migration and invasion in PANC-1 cells. Finally, through in vivo experiments, the effect of miR-887-3p on tumor growth was researched.

Results

We found that STARD13 expression is lower in pancreatic cancer tissues, with the level of miR-887-3p being higher in these tissues. Pancreatic cancer patients with particularly low levels of STARD13 presented with a poor prognosis. MiR-887-3p negatively regulates the expression of STARD13. Increasing levels of miR-887-3p decreased the expression of STARD13, which promoted the proliferation, cell cycle process, cell migration and invasion, and inhibited the apoptosis of pancreatic cancer cells. Inhibition of miR-887-3p in SCID mice could inhibit tumor growth and promote tumor cell apoptosis.

Conclusion

In conclusion, STARD13 is negatively regulated by miR-887-3p in pancreatic cancer. MiR-877-3p may act to promote cancer progression, and as such, it is a viable target for intervention and diagnostic development.

Circulating miRNAs in Small Extracellular Vesicles Secreted by a Human Melanoma Xenograft in Mouse Brains

The identification of liquid biomarkers remains a major challenge to improve the diagnosis of melanoma patients with brain metastases. Circulating miRNAs packaged into tumor-secreted small extracellular vesicles (sEVs) contribute to tumor progression. To investigate the release of tumor-secreted miRNAs by brain metastasis, we developed a xenograft model where human metastatic melanoma cells were injected intracranially in nude mice. The comprehensive profiles of both free miRNAs and those packaged in sEVs secreted by the melanoma cells in the plasma demonstrated that most (80%) of the sEV-associated miRNAs were also present in serum EVs from a cohort of metastatic melanomas, included in a publicly available dataset. Remarkably, among them, we found three miRNAs (miR-224-5p, miR-130a-3p and miR-21-5p) in sEVs showing a trend of upregulation during melanoma progression. Our model is proven to be valuable for identifying miRNAs in EVs that are unequivocally secreted by melanoma cells in the brain and could be associated to disease progression.

Phospholipase D as a key modulator of cancer progression

The phospholipase D (PLD) family has a ubiquitous expression in cells. PLD isoforms (PLDs) and their hydrolysate phosphatidic acid (PA) have been demonstrated to engage in multiple stages of cancer progression. Aberrant expression of PLDs, especially PLD1 and PLD2, has been detected in various cancers. Inhibition or elimination of PLDs activity has been shown to reduce tumour growth and metastasis. PLDs and PA also serve as downstream effectors of various cell-surface receptors, to trigger and regulate propagation of intracellular signals in the process of tumourigenesis and metastasis. Here, we discuss recent advances in understanding the functions of PLDs and PA in discrete stages of cancer progression, including cancer cell growth, invasion and migration, and angiogenesis, with special emphasis on the tumour-associated signalling pathways mediated by PLDs and PA and the functional importance of PLDs and PA in cancer therapy.

Dependence and Guidance Receptors-DCC and Neogenin-In Partial EMT and the Actions of Serine Proteases

The Epithelial-Mesenchymal Transition (EMT) is an important concept in understanding the processes of oncogenesis, especially with respect to the relationship between cell proliferation and metastatic properties such as spontaneous cell motility, chemotaxic migration and tissue invasion. EMT is now recognized as a more complex phenomenon than an all-or-nothing event, in which different components of the EMT may have distinct roles in the physio-pathological regulation of cell function and which may in turn depend on differential interactions with cell constituents and metabolic products. This mini-review summarizes recent work on the induction of cancer properties in parallel with the presence of EMT activities in the presence of serine proteases, with the focus on those tumor suppressors known as “dependence” receptors such as neogenin and Deleted in Colorectal Cancer (DCC). It is concluded that various forms of partial EMT should be given more detailed investigation and consideration as the results could have valuable implications for the development of disease-specific and patient-specific therapies.

Mammalian phospholipase D: Function, and therapeutics

Despite being discovered over 60 years ago, the precise role of phospholipase D (PLD) is still being elucidated. PLD enzymes catalyze the hydrolysis of the phosphodiester bond of glycerophospholipids producing phosphatidic acid and the free headgroup. PLD family members are found in organisms ranging from viruses, and bacteria to plants, and mammals. They display a range of substrate specificities, are regulated by a diverse range of molecules, and have been implicated in a broad range of cellular processes including receptor signaling, cytoskeletal regulation and membrane trafficking. Recent technological advances including: the development of PLD knockout mice, isoform-specific antibodies, and specific inhibitors are finally permitting a thorough analysis of the in vivo role of mammalian PLDs. These studies are facilitating increased recognition of PLD's role in disease states including cancers and Alzheimer's disease, offering potential as a target for therapeutic intervention.

HNRNPA2/B1 is upregulated in endocrine-resistant LCC9 breast cancer cells and alters the miRNA transcriptome when overexpressed in MCF-7 cells

MicroRNAs are dysregulated in breast cancer. Heterogeneous Nuclear Ribonucleoprotein A2/B1 (HNRNPA2/B1) is a reader of the N(6)-methyladenosine (m6A) mark in primary-miRNAs (pri-miRNAs) and promotes DROSHA processing to precursor-miRNAs (pre-miRNAs). We examined the expression of writers, readers, and erasers of m6A and report that HNRNPA2/B1 expression is higher in tamoxifen-resistant LCC9 breast cancer cells as compared to parental, tamoxifen-sensitive MCF-7 cells. To examine how increased expression of HNRNPA2/B1 affects miRNA expression, HNRNPA2/B1 was transiently overexpressed (~5.4-fold) in MCF-7 cells for whole genome miRNA profiling (miRNA-seq). 148 and 88 miRNAs were up- and down-regulated, respectively, 48 h after transfection and 177 and 172 up- and down-regulated, respectively, 72 h after transfection. MetaCore Enrichment analysis identified progesterone receptor action and transforming growth factor β (TGFβ) signaling via miRNA in breast cancer as pathways downstream of the upregulated miRNAs and TGFβ signaling via SMADs and Notch signaling as pathways of the downregulated miRNAs. GO biological processes for mRNA targets of HNRNPA2/B1-regulated miRNAs included response to estradiol and cell-substrate adhesion. qPCR confirmed HNRNPA2B1 downregulation of miR-29a-3p, miR-29b-3p, and miR-222 and upregulation of miR-1266-5p, miR-1268a, miR-671-3p. Transient overexpression of HNRNPA2/B1 reduced MCF-7 sensitivity to 4-hydroxytamoxifen and fulvestrant, suggesting a role for HNRNPA2/B1 in endocrine-resistance.

Prognostic significance and biological function of Lamina-associated polypeptide 2 in non-small-cell lung cancer

Purpose: Lamina-associated polypeptide 2 (LAP2; encoded by TMPO), is a nuclear protein that may affect chromatin regulation and gene expression through dynamically binding to nuclear lamin. TMPO (LAP2) plays dual roles of either suppressing or promoting proliferation of cells, depending on the status of the cell. It has been reported that TMPO is up-regulated in various cancer types. However, its function in lung cancer has not been studied yet.

Materials and methods: A series of clinical microarray datasets for lung cancer were investigated to demonstrate the expression of TMPO. The transcription of TMPO gene in human lung cancer was analyzed using Oncomine platform (www.oncomine.org) according to the standardized procedures described previously. Four separate datasets (Hou Lung, Okayama Lung, Beer Lung, and Garber Lung) were analyzed.

Results: Here, we show that TMPO is over-expressed in lung cancer tissues, and that a high level of TMPO indicates a poor prognosis in lung cancer patients. Knockdown of TMPO in lung cancer cells inhibits cell proliferation and induces apoptosis. Also, down-regulation of TMPO leads to an impaired metastatic ability of tumor cells. A nude mice tumor model show that knockdown of TMPO suppresses tumor formation in vivo.

Conclusion: Collectively, this study suggests TMPO as an oncogene and a novel prognostic gene in lung cancer.

Lack of effective translational regulation of PLD expression and exosome biogenesis in triple-negative breast cancer cells

Triple-negative breast cancer (TNBC) is an aggressive subtype of breast cancer that is difficult to treat since cells lack the three receptors (ES, PR, or HER) that the most effective treatments target. We have used a well-established TNBC cell line (MDA-MB-231) from which we found evidence in support for a phospholipase D (PLD)-mediated tumor growth and metastasis: high levels of expression of PLD, as well as the absence of inhibitory miRs (such as miR-203) and 3'-mRNA PARN deadenylase activity in these cells. Such findings are not present in a luminal B cell line, MCF-7, and we propose a new miR•PARN•PLD node that is not uniform across breast cancer molecular subtypes and as such TNBC could be pharmacologically targeted differentially. We review the participation of PLD and phosphatidic acid (PA), its enzymatic product, as new "players" in breast cancer biology, with the aspects of regulation of the tumor microenvironment, macrophage polarization, regulation of PLD transcripts by specific miRs and deadenylases, and PLD-regulated exosome biogenesis. A new signaling miR•PARN•PLD node could serve as new biomarkers for TNBC abnormal signaling and metastatic disease staging, potentially before metastases are able to be visualized using conventional imaging.

Vimentin on the move: new developments in cell migration

The vimentin gene ( VIM) encodes one of the 71 human intermediate filament (IF) proteins, which are the building blocks of highly ordered, dynamic, and cell type-specific fiber networks. Vimentin is a multi-functional 466 amino acid protein with a high degree of evolutionary conservation among vertebrates. Vim ^−/− mice, though viable, exhibit systemic defects related to development and wound repair, which may have implications for understanding human disease pathogenesis. Vimentin IFs are required for the plasticity of mesenchymal cells under normal physiological conditions and for the migration of cancer cells that have undergone epithelial–mesenchymal transition. Although it was observed years ago that vimentin promotes cell migration, the molecular mechanisms were not completely understood. Recent advances in microscopic techniques, combined with computational image analysis, have helped illuminate vimentin dynamics and function in migrating cells on a precise scale. This review includes a brief historical account of early studies that unveiled vimentin as a unique component of the cell cytoskeleton followed by an overview of the physiological vimentin functions documented in studies on Vim ^−/− mice. The primary focus of the discussion is on novel mechanisms related to how vimentin coordinates cell migration. The current hypothesis is that vimentin promotes cell migration by integrating mechanical input from the environment and modulating the dynamics of microtubules and the actomyosin network. These new findings undoubtedly will open up multiple avenues to study the broader function of vimentin and other IF proteins in cell biology and will lead to critical insights into the relevance of different vimentin levels for the invasive behaviors of metastatic cancer cells.

An Antithrombotic Strategy by Targeting Phospholipase D in Human Platelets

Phospholipase D (PLD) is involved in many biological processes. PLD1 plays a crucial role in regulating the platelet activity of mice; however, the role of PLD in the platelet activation of humans remains unclear. Therefore, we investigated whether PLD is involved in the platelet activation of humans. Our data revealed that inhibition of PLD1 or PLD2 using pharmacological inhibitors effectively inhibits platelet aggregation in humans. However, previous studies have showed that PLD1 or PLD2 deletion did not affect mouse platelet aggregation in vitro, whereas only PLD1 deletion inhibited thrombus formation in vivo. Intriguingly, our data also showed that the pharmacological inhibition of PLD1 or PLD2 does not affect mouse platelet aggregation in vitro, whereas the inhibition of only PLD1 delayed thrombus formation in vivo. These findings indicate that PLD may play differential roles in humans and mice. In humans, PLD inhibition attenuates platelet activation, adhesion, spreading, and clot retraction. For the first time, we demonstrated that PLD1 and PLD2 are essential for platelet activation in humans, and PLD plays different roles in platelet function in humans and mice. Our findings also indicate that targeting PLD may provide a safe and alternative therapeutic approach for preventing thromboembolic disorders.

Serine protease modulation of Dependence Receptors and EMT protein expression

Expression of the tumour suppressor Deleted in Colorectal Cancer (DCC) and the related protein neogenin is reduced by the mammalian serine protease chymotrypsin or the bacterial serine protease subtilisin, with increased cell migration. The present work examines whether these actions are associated with changes in the expression of cadherins, β-catenin and vimentin, established markers of the Epithelial-Mesenchymal Transition (EMT) which has been linked with cell migration and tumour metastasis. The results confirm the depletion of DCC and neogenin and show that chymotrypsin and subtilisin also reduce expression of β-catenin in acutely prepared tissue sections but not in human mammary adenocarcinoma MCF-7 or MDA-MB-231 cells cultured in normal media, or primary normal human breast cells. A loss of β-catenin was also seen in low serum media but transfecting cells with a dcc-containing plasmid induced resistance. E-cadherin was not consistently affected but vimentin was induced by low serum-containing media and was increased by serine proteases in MCF-7 and MDA-MB-231 cells in parallel with increased wound closure. Vimentin might contribute to the promotion of cell migration. The results suggest that changes in EMT proteins depend on the cells or tissues concerned and do not parallel the expression of DCC and neogenin. The increased cell migration induced by serine proteases is not consistently associated with the expression of the EMT proteins implying either that the increased migration may be independent of EMT or supporting the view that EMT is not itself consistently related to migration. (241).

miR-103 promotes the metastasis and EMT of hepatocellular carcinoma by directly inhibiting LATS2

Improving the long-term survival of patients with hepatocellular carcinoma (HCC) remains a challenge due to metastasis and recurrence. In this study, we demonstrate that the overexpression of miR-103 in HCC cells promotes epithelial-mesenchymal transition (EMT), and is associated with an enhanced metastasis and poor outcomes, as shown by western blot analysis and immunohistochemistry. Mechanistically, using reporter luciferase assay we reveal that the serine/threonine-protein kinase, large tumor suppressor kinase 2 (LATS2), a key component of the Hippo signaling pathway, is a direct target of miR-103 in HCC cells. Transwell assay, MTT assay and western blot analysis were performed to reveal that LATS2 can counteract the functional effects of miR-103 on HCC metastasis, growth and EMT. The analyses of clinical data indicated that a high expression of miR-103 correlated with a high expression of vimentin, but with a low expression of LATS2 and E-cadherin in HCC tissues. miR-103 also reduced yes-associated protein (YAP) phosphorylation. On the whole, the findings of this study suggest that miR-103 promotes HCC metastasis and EMT by directly inhibiting LATS2. Thus, targeting miR-103/LATS2 may prove to be a promising therapeutic strategy for HCC.

MicroRNAs in regulation of triple-negative breast cancer progression

PURPOSE

Dysregulation of miRNA profile has been associated with a broad spectrum of cellular processes underlying progression of various human malignancies. Increasing evidence suggests that specific microRNA clusters might be of clinical utility, especially in triple-negative breast carcinoma (TNBC), devoid of both predictive markers and potential therapeutic targets. Here we provide a comprehensive review of the existing data on microRNAs in TNBC, their molecular targets, a putative role in invasive progression with a particular emphasis on the epithelial-to-mesenchymal transition (EMT) and acquisition of stem-cell properties (CSC), regarded both as prerequisites for metastasis, and significance for therapy.

METHODS

PubMed and Medline databases were systematically searched for the relevant literature. 121 articles have been selected and thoroughly analysed.

RESULTS

Several miRNAs associated with EMT/CSC and invasion were identified as significantly (1) upregulated: miR-10b, miR-21, miR-29, miR-9, miR-221/222, miR-373 or (2) downregulated: miR-145, miR-199a-5p, miR-200 family, miR-203, miR-205 in TNBC. Dysregulation of miR-10b, miR-21, miR-29, miR-145, miR-200 family, miR-203, miR-221/222 was reported of prognostic value in TNBC patients.

CONCLUSION

Available data suggest that specific microRNA clusters might play an important role in biology of TNBC, understanding of which should assist disease prognostication and therapy.

USP14 de-ubiquitinates vimentin and miR-320a modulates USP14 and vimentin to contribute to malignancy in gastric cancer cells

Vimentin plays important roles in the epithelial-to-mesenchymal transition (EMT). In this study, we found that vimentin was highly expressed in human gastric cancer (GC) tissues and cell lines and significantly promoted cell growth, migration and invasion. Ubiquitin-specific protease 14 (USP14) interacted with the vimentin protein, which led to its de-ubiquitination. miR-320a was found to bind to the 3′UTR of both vimentin and USP14 transcripts and downregulate the expression of both proteins. The downregulation of miR-320a upregulates vimentin expression by directly binding to the 3′UTR of vimentin to derepress expression and indirectly by augmenting USP14 to increase vimentin stability in GC cells. Taken together, these results provide new insight into malignancy in gastric cancers.

REST represses miR-124 and miR-203 to regulate distinct oncogenic properties of glioblastoma stem cells

Background

Glioblastoma (GBM) is one of the most common, aggressive, and invasive human brain tumors. There are few reliable mechanism-based therapeutic approaches for GBM patients. The transcriptional repressor RE1 silencing transcriptional factor (REST) regulates the oncogenic properties of a class of GBM stem-like cells (high-REST [HR]-GSCs) in humans. However, it has been unclear whether REST represses specific targets to regulate specific oncogenic functions or represses all targets with overlapping functions in GSCs.

Methods

We used genome-wide, biochemical, and mouse intracranial tumorigenic assays to identify and determine functions of microRNA (miR) targets of REST in 2 independent HR-GSC lines.

Results

Here we show that REST represses 2 major miR gene targets in HR-GSCs: miR-203, a new target, and miR-124, a known target. Gain of function of miR-124 or miR-203 in HR-GSCs increased survival in tumor-bearing mice. Importantly, the increased survival of tumor-bearing mice caused by knockdown of REST in HR-GSCs was reversed by double knockdown of REST and either miR-203 or miR-124, indicating that these 2 miRs are critical tumor suppressors that are repressed in REST-mediated tumorigenesis. We further show that while miR-124 and the REST-miR-124 pathways regulate self-renewal, apoptosis and invasion, miR-203 and the REST-miR-203 pathways regulate only invasion. We further identify and validate potential mRNA targets of miR-203 and miR-124 in REST-mediated HR-GSC tumor invasion.

Conclusions

These findings indicate that REST regulates its miR gene targets with overlapping functions and suggest how REST maintains oncogenic competence in GSCs. These mechanisms could potentially be utilized to block REST-mediated GBM tumorigenesis.

MiR-206 suppresses epithelial mesenchymal transition by targeting TGF-β signaling in estrogen receptor positive breast cancer cells

Background: Previous reports have shown a mutual negative feedback loop between microRNA (miR)-206 and estrogen receptor (ER) expression. Furthermore, decreased miR-206 expression in breast cancer (BC) is associated with the advanced clinical stage and lymph node metastasis. However, its role and the mechanism underlying the migration and invasion of ER positive BC remain unclear.

Results: In this study, miR-206 was stably transfected into ER positive cell lines MCF-7 and T47D to investigate the effect of miR-206. The results showed that miR-206 overexpression markedly impaired the migration and invasive abilities of these cells, followed by suppression of the epithelial mesenchymal transition (EMT). Mechanistic analyses showed that miR-206 inhibited the autocrine production of transforming growth factor (TGF)-β as well as the downstream expression of neuropilin-1 (NRP1) and SMAD2, responsible for the decreased migration, invasion, and EMT in these cells.

Conclusions: Our data demonstrate that miR-206 inhibits TGF-β transcription and autocrine production, as well as downstream target genes of EMT. Restoring miR-206 expression may provide an effective therapeutic strategy for ER positive BC.

MiR-195 suppresses the metastasis and epithelial-mesenchymal transition of hepatocellular carcinoma by inhibiting YAP

MiR-195, a novel cancer-related microRNA, was previously reported to play an important role in many malignancies. This study aimed to investigate the role of miR-195 mediated epithelial-mesenchymal transition (EMT) and the progression of hepatocellular carcinoma (HCC) as well as the underlying mechanisms. Our result demonstrated that miR-195 were significantly down regulated in HCC and its decreased expression is associated with poor clinical features of HCC patients. Oppositely, expression level of YAP was significantly higher in HCC tissues, and the level of YAP in metastatic tissues was significantly higher. We also found that a strong inversely association between low level expression of miR-195 and high level of YAP in HCC tissues. Notably, this study confirmed that miR-195, YAP and their combination were valuable predictors for the prognosis of HCC patients. We also explored that miR-195 inhibits HCC growth and metastatic capacity. Mechanistically, we confirm that miR-195 inhibits the migration, invasion and EMT of HCC cells by suppressing YAP. Lastly, we revealed YAP was not only the downstream of miR-195 in HCC, but also mediated the promoting effects of miR-195 on the metastasis and EMT of HCC cells. Taken together, miR-195 inhibits the metastasis and EMT in HCC by targeting YAP. MiR-195/YAP pathway may potentially act as novel biomarker and attractive therapeutic target in HCC.

How miRs and mRNA deadenylases could post-transcriptionally regulate expression of tumor-promoting protein PLD

Phospholipase D (PLD) plays a key role in both cell membrane lipid reorganization and architecture, as well as a cell signaling protein via the product of its enzymatic reaction, phosphatidic acid (PA). PLD is involved in promoting breast cancer cell growth, proliferation, and metastasis and both gene and protein expression are upregulated in breast carcinoma human samples. In spite of all this, the ultimate reason as to why PLD expression is high in cancer cells vs. their normal counterparts remains largely unknown. Until we understand this and the associated signaling pathways, it will be difficult to establish PLD as a bona fide target to explore new potential cancer therapeutic approaches. Recently, our lab has identified several molecular mechanisms by which PLD expression is high in breast cancer cells and they all involve post-transcriptional control of its mRNA. First, PA, a mitogen, functions as a protein and mRNA stabilizer that counteracts natural decay and degradation. Second, there is a repertoire of microRNAs (miRs) that keep PLD mRNA translation at low levels in normal cells, but their effects change with starvation and during endothelial-to-mesenchymal transition (EMT) in cancer cells. Third, there is a novel way of post-transcriptional regulation of PLD involving 3'-exonucleases, specifically the deadenylase, Poly(A)-specific Ribonuclease (PARN), which tags mRNA for mRNA for degradation. This would enable PLD accumulation and ultimately breast cancer cell growth. We review in depth the emerging field of post-transcriptional regulation of PLD, which is only recently beginning to be understood. Since, surprisingly, so little is known about post-transcriptional regulation of PLD and related phospholipases (PLC or PLA), this new knowledge could help our understanding of how post-transcriptional deregulation of a lipid enzyme expression impacts tumor growth.

A feedback mechanism between PLD and deadenylase PARN for the shortening of eukaryotic poly(A) mRNA tails that is deregulated in cancer cells

The removal of mRNA transcript poly(A) tails by 3′→5′ exonucleases is the rate-limiting step in mRNA decay in eukaryotes. Known cellular deadenylases are the CCR4-NOT and PAN complexes, and poly(A)-specific ribonuclease (PARN). The physiological roles and regulation for PARN is beginning to be elucidated. Since phospholipase D (PLD2 isoform) gene expression is upregulated in breast cancer cells and PARN is downregulated, we examined whether a signaling connection existed between these two enzymes. Silencing PARN with siRNA led to an increase in PLD2 protein, whereas overexpression of PARN had the opposite effect. Overexpression of PLD2, however, led to an increase in PARN expression. Thus, PARN downregulates PLD2 whereas PLD2 upregulates PARN. Co-expression of both PARN and PLD2 mimicked this pattern in non-cancerous cells (COS-7 fibroblasts) but, surprisingly, not in breast cancer MCF-7 cells, where PARN switches from inhibition to activation of PLD2 gene and protein expression. Between 30 and 300 nM phosphatidic acid (PA), the product of PLD enzymatic reaction, added exogenously to culture cells had a stabilizing role of both PARN and PLD2 mRNA decay. Lastly, by immunofluorescence microscopy, we observed an intracellular co-localization of PA-loaded vesicles (0.1-1 nm) and PARN. In summary, we report for the first time the involvement of a phospholipase (PLD2) and PA in mediating PARN-induced eukaryotic mRNA decay and the crosstalk between the two enzymes that is deregulated in breast cancer cells.

Summary: Cell signaling enzyme phospholipase D2 (PLD2) and its reaction product, phospholipid phosphatidic acid (PA), are involved in mediating PARN-induced eukaryotic mRNA decay.