12,921 research outputs found

    Upregulated MicroRNA-29a by Hepatitis B Virus X Protein Enhances Hepatoma Cell Migration by Targeting PTEN in Cell Culture Model

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    Hepatitis B virus X protein (HBx) plays important roles in the development of hepatocellular carcinoma (HCC). MicroRNAs (miRNAs) contribute to cancer development by acting as oncogenes or tumor suppressors. Previously, we reported that HBx was able to promote the migration of hepatoma HepG2 cells. However, the regulation of miRNAs in the development of HBV-related HCC is poorly understood. In the present study, we reported that miR-29a was a novel regulator of migration of hepatoma cells mediated by HBx. Our data showed that the expression of miR-29a was dramatically increased in p21-HBx transgenic mice, HBx-transfected hepatoma HepG2-X (or H7402-X) cells and HepG2.2.15 cells that constitutively replicate HBV. However, our data showed that miR-29a was upregulated in 4 of the 11 clinical HCC samples. We found that the overexpression of miR-29a promoted the migration of HepG2 cells, while a specific miR-29a inhibitor could partially abolish the enhanced migration of HepG2-X cells. Moreover, we identified PTEN was one of the target genes of miR-29a in HepG2 cells. The deletion of the miR-29a-binding site was able to abolish the role of miR-29a in suppression of luciferase activity of the PTEN 3′UTR reporter. Meanwhile, the overexpression of PTEN was able to reverse the promoted migration of HepG2 cells mediated by miR-29a. Moreover, our data showed that the modulation of Akt phosphorylation, a downstream factor of PTEN, was involved in the cell migration enhanced by miR-29a, suggesting that miR-29a is responsible for the cell migration through its target gene PTEN. Thus, we conclude that miR-29a is involved in the regulation of migration of hepatoma cells mediated by HBx through PTEN in cell culture model

    Novel role of miR-29a in pancreatic cancer autophagy and its therapeutic potential

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    Pancreatic Ductal Adenocarcinoma (PDAC) is a highly lethal malignancy that responds poorly to current therapeutic modalities. In an effort to develop novel therapeutic strategies, we found downregulation of miR-29 in pancreatic cancer cells, and overexpression of miR-29a sensitized chemotherapeutic resistant pancreatic cancer cells to gemcitabine, reduced cancer cell viability, and increased cytotoxicity. Furthermore, miR-29a blocked autophagy flux, as evidenced by an accumulation of autophagosomes and autophagy markers, LC3B and p62, and a decrease in autophagosome-lysosome fusion. In addition, miR-29a decreased the expression of autophagy proteins, TFEB and ATG9A, which are critical for lysosomal function and autophagosome trafficking respectively. Knockdown of TFEB or ATG9A inhibited autophagy similar to miR-29a overexpression. Finally, miR-29a reduced cancer cell migration, invasion, and anchorage independent growth. Collectively, our findings indicate that miR-29a functions as a potent autophagy inhibitor, sensitizes cancer cells to gemcitabine, and decreases their invasive potential. Our data provides evidence for the use of miR-29a as a novel therapeutic agent to target PDAC

    The microRNA-29 family in cartilage homeostasis and osteoarthritis

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    MicroRNAs have been shown to function in cartilage development and homeostasis, as well as in progression of osteoarthritis. The objective of the current study was to identify microRNAs involved in the onset or early progression of osteoarthritis and characterise their function in chondrocytes. MicroRNA expression in mouse knee joints post-DMM surgery was measured over 7 days. Expression of miR-29b-3p was increased at day 1 and regulated in the opposite direction to its potential targets. In a mouse model of cartilage injury and in end-stage human OA cartilage, the miR-29 family were also regulated. SOX9 repressed expression of miR-29a-3p and miR-29b-3p via the 29a/b1 promoter. TGFβ1 decreased expression of miR-29a, b and c (3p) in primary chondrocytes, whilst IL-1β increased (but LPS decreased) their expression. The miR-29 family negatively regulated Smad, NFκB and canonical WNT signalling pathways. Expression profiles revealed regulation of new WNT-related genes. Amongst these, FZD3, FZD5, DVL3, FRAT2, CK2A2 were validated as direct targets of the miR-29 family. These data identify the miR-29 family as microRNAs acting across development and progression of OA. They are regulated by factors which are important in OA and impact on relevant signalling pathways

    Identification and validation of oncologic miRNA biomarkers for Luminal A-like breast cancer

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    Introduction: Breast cancer is a common disease with distinct tumor subtypes phenotypically characterized by ER and HER2/neu receptor status. MiRNAs play regulatory roles in tumor initiation and progression, and altered miRNA expression has been demonstrated in a variety of cancer states presenting the potential for exploitation as cancer biomarkers. Blood provides an excellent medium for biomarker discovery. This study investigated systemic miRNAs differentially expressed in Luminal A-like (ER+PR+HER2/neu-) breast cancer and their effectiveness as oncologic biomarkers in the clinical setting. Methods: Blood samples were prospectively collected from patients with Luminal A-like breast cancer (n=54) and controls (n=56). RNA was extracted, reverse transcribed and subjected to microarray analysis (n=10 Luminal A-like; n=10 Control). Differentially expressed miRNAs were identified by artificial neural network (ANN) data-mining algorithms. Expression of specific miRNAs was validated by RQ-PCR (n=44 Luminal A; n=46 Control) and potential relationships between circulating miRNA levels and clinicopathological features of breast cancer were investigated. Results: Microarray analysis identified 76 differentially expressed miRNAs. ANN revealed 10 miRNAs for further analysis ( miR-19b, miR-29a, miR-93, miR-181a, miR-182, miR-223, miR-301a, miR-423-5p, miR-486-5 and miR-652 ). The biomarker potential of 4 miRNAs ( miR-29a, miR-181a , miR-223 and miR-652 ) was confirmed by RQ-PCR, with significantly reduced expression in blood of women with Luminal A-like breast tumors compared to healthy controls (p=0.001, 0.004, 0.009 and 0.004 respectively). Binary logistic regression confirmed that combination of 3 of these miRNAs ( miR-29a, miR-181a and miR-652 ) could reliably differentiate between cancers and controls with an AUC of 0.80. Conclusion: This study provides insight into the underlying molecular portrait of Luminal A-like breast cancer subtype. From an initial 76 miRNAs, 4 were validated with altered expression in the blood of women with Luminal A-like breast cancer. The expression profiles of these 3 miRNAs, in combination with mammography, has potential to facilitate accurate subtype- specific breast tumor detection

    Loss of miR-107, miR-181c and miR-29a-3p promote activation of Notch2 signaling in pediatric high-grade gliomas (pHGGs)

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    The mechanisms by which microRNAs control pediatric high-grade gliomas (pHGGs) have yet to be fully elucidated. Our studies of patient-derived pHGG tissues and of the pHGG cell line KNS42 revealed down-regulation in these tumors of three microRNAs, specifically miR-107, miR-181c, and miR-29a-3p. This down-regulation increases the proliferation of KNS42 cells by de-repressing expression of the Notch2 receptor (Notch2), a validated target of miR-107 and miR-181c and a putative target of miR-29a-3p. Inhibition (either pharmacologic or genetic) of Notch2 or re-expression of the implicated microRNAs (all three combined but also individually) significantly reduced KNS42 cell proliferation. These findings suggest that Notch2 pathway activation plays a critical role in pHGGs growth and reveal a direct epigenetic mechanism that controls Notch2 expression, which could potentially be targeted by novel forms of therapy for these childhood tumors characterized by high-morbidity and high-mortality

    A Comprehensive Study to Delineate the Role of an Extracellular Vesicle-Associated MicroRNA-29a in Chronic Methamphetamine Use Disorder

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    Extracellular vesicles (EVs), which express a repertoire of cargo molecules (cf. proteins, microRNA, lipids, etc.), have been garnering a prominent role in the modulation of several cellular processes. Here, using both non-human primate and rodent model systems, we provide evidence that brain-derived EV (BDE) miRNA, miR-29a-3p (mir-29a), is significantly increased during chronic methamphetamine (MA) exposure. Further, miR-29a levels show significant increase both with drug-seeking and reinstatement in a rat MA self-administration model. We also show that EV-associated miR-29a is enriched in EV pool comprising of small EVs and exomeres and further plays a critical role in MA-induced inflammation and synaptodendritic damage. Furthermore, treatment with the anti-inflammatory drug ibudilast (AV411), which is known to reduce MA relapse, decreased the expression of miR-29a and subsequently attenuated inflammation and rescued synaptodendritic injury. Finally, using plasma from MUD subjects, we provide translational evidence that EV-miR29a could potentially serve as a biomarker to detect neuronal damage in humans diagnosed with MA use disorder (MUD). In summary, our work suggests that EV-associated miR-29a-3p plays a crucial role in MUD and might be used as a potential blood-based biomarker for detecting chronic inflammation and synaptic damage

    A comprehensive study to delineate the role of an extracellular vesicle-associated microRNA-29a in chronic methamphetamine use disorder

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    Extracellular vesicles (EVs), which express a repertoire of cargo molecules (cf. proteins, microRNA, lipids, etc.), have been garnering a prominent role in the modulation of several cellular processes. Here, using both non-human primate and rodent model systems, we provide evidence that brain-derived EV (BDE) miRNA, miR- 29a-3p (mir-29a), is significantly increased during chronic methamphetamine (MA) exposure. Further, miR-29a levels show significant increase both with drug-seeking and reinstatement in a rat MA self-administration model. We also show that EVassociated miR-29a is enriched in EV pool comprising of small EVs and exomeres and further plays a critical role in MA-induced inflammation and synaptodendritic damage. Furthermore, treatment with the anti-inflammatory drug ibudilast (AV411), which is known to reduce MA relapse, decreased the expression of miR-29a and subsequently attenuated inflammation and rescued synaptodendritic injury. Finally, using plasma fromMUDsubjects, we provide translational evidence that EV-miR29a could potentially serve as a biomarker to detect neuronal damage in humans diagnosed with MA use disorder (MUD). In summary, our work suggests that EVassociated miR-29a-3p plays a crucial role in MUD and might be used as a potential blood-based biomarker for detecting chronic inflammation and synaptic damage

    Endoplasmic reticulum stress-mediated upregulation of miR-29a enhances sensitivity to neuronal apoptosis.

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    Disturbance of homeostasis within the endoplasmic reticulum (ER) lumen leads to the accumulation of unfolded and misfolded proteins. This results in the activation of an evolutionary conserved stress response termed ER stress that, if unresolved, induces apoptosis. Previously the Bcl-2 homology domain 3-Only Protein Puma was identified as a mediator of ER stress-induced apoptosis in neurons. In the search of alternative contributors to ER stress-induced apoptosis, a downregulation of the anti-apoptotic Bcl-2 family protein Mcl-1 was noted during ER stress in both mouse cortical neurons and human SH-SY5Y neuroblastoma cells. Downregulation of Mcl-1 was associated with an upregulation of microRNA-29a (miR-29a) expression, and subsequent experiments showed that miR-29a targeted the 3\u27-untranslated region of the anti-apoptotic Bcl-2 family protein, Mcl-1. Inhibition of miR-29a expression using sequence-specific antagomirs or the overexpression of Mcl-1 decreased cell death following tunicamycin treatment, while gene silencing of Mcl-1 increased cell death. miR-29a did not alter the signalling branches of the ER stress response, rather its expression was controlled by the ER stress-induced transcription factor activating-transcription-factor-4 (ATF4). The current data demonstrate that the ATF4-mediated upregulation of miR-29a enhances the sensitivity of neurons to ER stress-induced apoptosis

    miRNA-29a reverses P-glycoprotein-mediated drug resistance and inhibits proliferation via up-regulation of PTEN in colon cancer cells

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    Colon cancer is a serious malignant type of cancer in the world. Acquisition of multi-drug resistance (MDR) during chemotherapy is still a controversial challenge during cancer treatment. Accordingly, detection of safe and impressive MDR-reversing targets such as microRNAs (miRNAs/miRs) can play critical role in cancer treatment. Here, the functional effects of miR-29a in chemo-resistant colon cancer cells is scrutinized. The effect of doxorubicin (DOX) on cell proliferation after miR-29a transfection has been evaluated using MTT assay in HT29 and HT29/DOX cells. Rhodamine123 (Rh123) assay is used to identify the activity of common drug efflux through membrane transporters P-glycoprotein (P-gp). P-gp and PTEN mRNA/protein expression levels were measured by reverse transcription-quantitative polymerase chain reaction (RT-qPCR) and Western blot analyses. Flow cytometry was employed to the investigation of apoptosis. ANOVA followed by Bonferroni's and Sidak's tests were used to compare the data from different groups. Thus, it was shown that miRNA-29a overexpression considerably inhibited the HT29/DOX viability. miR-29a significantly down-regulated P-gp expression and activity in HT29/DOX cells and declined drug resistance through elevation of intracellular DOX. Furthermore, upon miRNA-29a transfection, PTEN expression could be restored in resistant cells. These results have indicated that miR-29a target PTEN ultimately P-gp, which is downstream of PTEN, inhibit drug resistance, proliferation, and apoptosis through PI3K/Akt pathway. As a result, miR-29a overexpression is led to enhance the sensitivity of HT29/DOX cells to DOX-treatment by targeting P-gp. MiR-29a might proffer a novel promising candidate for colon cancer therapeutics during chemotherapy. © 202

    miR-29a Is Repressed by MYC in Pancreatic Cancer and Its Restoration Drives Tumor-Suppressive Effects via Downregulation of LOXL2

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    Pancreatic ductal adenocarcinoma (PDAC) is an intractable cancer with a dismal prognosis. MicroRNA-29a (miR-29a) is commonly downregulated in PDAC, however, mechanisms for its loss and role still remain unclear. Here we show that in PDAC, repression of miR-29a is directly mediated by MYC via promoter activity. RNA-seq analysis, integrated with miRNA target prediction, identified global miR-29a downstream targets in PDAC. Target enrichment coupled with gene ontology and survival correlation analyses identified the top five miR-29a downregulated target genes (LOXL2, MYBL2, CLDN1, HGK and NRAS) that are known to promote tumorigenic mechanisms. Functional validation confirmed that upregulation of miR-29a is sufficient to ablate translational expression of these five genes in PDAC. We show that the most promising target among the identified genes, LOXL2, is repressed by miR-29a via 3’-UTR binding. Pancreatic tissues from a PDAC murine model and patient biopsies showed overall high LOXL2 expression with inverse correlations with miR-29a levels. Collectively, our data delineate an anti-tumorigenic, regulatory role of miR-29a, and a novel MYC-miR-29a-LOXL2 regulatory axis in PDAC pathogenesis, indicating the potential of the molecule in therapeutic opportunities. Implications This study unravels a novel functional role of miR-29a in PDAC pathogenesis, and identifies a MYC-miR-29a-LOXL2 axis in regulation of the disease progression, implicating miR-29a as a potential therapeutic target for PDAC
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