MiR-148a regulates the growth and apoptosis in pancreatic cancer by targeting CCKBR and Bcl-2

MicroRNA-Mediated Regulation of Histone-Modifying Enzymes in Cancer: Mechanisms and Therapeutic Implications

In the past decade, significant advances in molecular research have provided a deeper understanding of the intricate regulatory mechanisms involved in carcinogenesis. MicroRNAs, short non-coding RNA sequences, exert substantial influence on gene expression by repressing translation or inducing mRNA degradation. In the context of cancer, miRNA dysregulation is prevalent and closely associated with various stages of carcinogenesis, including initiation, progression, and metastasis. One crucial aspect of the cancer phenotype is the activity of histone-modifying enzymes that govern chromatin accessibility for transcription factors, thus impacting gene expression. Recent studies have revealed that miRNAs play a significant role in modulating these histone-modifying enzymes, leading to significant implications for genes related to proliferation, differentiation, and apoptosis in cancer cells. This article provides an overview of current research on the mechanisms by which miRNAs regulate the activity of histone-modifying enzymes in the context of cancer. Both direct and indirect mechanisms through which miRNAs influence enzyme expression are discussed. Additionally, potential therapeutic implications arising from miRNA manipulation to selectively impact histone-modifying enzyme activity are presented. The insights from this analysis hold significant therapeutic promise, suggesting the utility of miRNAs as tools for the precise regulation of chromatin-related processes and gene expression. A contemporary focus on molecular regulatory mechanisms opens therapeutic pathways that can effectively influence the control of tumor cell growth and dissemination.

Microbiome and MicroRNA or Long Non-Coding RNA-Two Modern Approaches to Understanding Pancreatic Ductal Adenocarcinoma

Pancreatic ductal adenocarcinoma (PDAC) is one of humans' most common and fatal neoplasms. Nowadays, a number of PDAC studies are being conducted in two different fields: non-coding RNA (especially microRNA and long non-coding RNA) and microbiota. It has been recently discovered that not only does miRNA affect particular bacteria in the gut microbiome that can promote carcinogenesis in the pancreas, but the microbiome also has a visible impact on the miRNA. This suggests that it is possible to use the combined impact of the microbiome and noncoding RNA to suppress the development of PDAC. Nevertheless, insufficient research has focused on bounding both approaches to the diagnosis, treatment, and prevention of pancreatic ductal adenocarcinoma. In this article, we summarize the recent literature on the molecular basis of carcinogenesis in the pancreas, the two-sided impact of particular types of non-coding RNA and the pancreatic cancer microbiome, and possible medical implications of the discovered phenomenon.

CiberAMP: An R Package to Identify Differential mRNA Expression Linked to Somatic Copy Number Variations in Cancer Datasets

Simple Summary

The ability to establish accurate correlations between the number of copies of genes and the expression levels of their encoded transcripts remains a challenge despite the extensive progress made in the understanding of the genome of cancer cells. Here, we describe a new algorithm that does so by integrating both genomics and transcriptomics data from the Cancer Genome Atlas. In addition to explaining the step-by-step basis of this new method, we provide examples of how this new algorithm can help identify functionally meaningful gene copy alterations that are recurrently detected in cancer patients.

Abstract

Somatic copy number variations (SCNVs) are genetic alterations frequently found in cancer cells. These genetic alterations can lead to concomitant perturbations in the expression of the genes included in them and, as a result, promote a selective advantage to cancer cells. However, this is not always the case. Due to this, it is important to develop in silico tools to facilitate the accurate identification and functional cataloging of gene expression changes associated with SCNVs from pan-cancer data. Here, we present a new R-coded tool, designated as CiberAMP, which utilizes genomic and transcriptomic data contained in the Cancer Genome Atlas (TCGA) to identify such events. It also includes information on the genomic context in which such SCNVs take place. By doing so, CiberAMP provides clues about the potential functional relevance of each of the SCNV-associated gene expression changes found in the interrogated tumor samples. The main features and advantages of this new algorithm are illustrated using glioblastoma data from the TCGA database.

An Extensive Review on Preclinical and Clinical Trials of Oncolytic Viruses Therapy for Pancreatic Cancer

Chemotherapy resistance and peculiar tumor microenvironment, which diminish or mitigate the effects of therapies, make pancreatic cancer one of the deadliest malignancies to manage and treat. Advanced immunotherapies are under consideration intending to ameliorate the overall patient survival rate in pancreatic cancer. Oncolytic viruses therapy is a new type of immunotherapy in which a virus after infecting and lysis the cancer cell induces/activates patients’ immune response by releasing tumor antigen in the blood. The current review covers the pathways and molecular ablation that take place in pancreatic cancer cells. It also unfolds the extensive preclinical and clinical trial studies of oncolytic viruses performed and/or undergoing to design an efficacious therapy against pancreatic cancer.

miR-148a-3p inhibits the proliferation and migration of bladder cancer via regulating the expression of ROCK-1

PURPOSE

To investigate the mechanism of miR-148a-3p regulating the proliferation and migration of bladder tumor cells.

MATERIALS AND METHODS

We conducted a preliminary study to detect the relative expression of miR-148a-3p in bladder cancer and para-cancerous tissue samples. Three bladder tumor cell lines, T24, 5,637 and UM-UC-3, were selected. The expression levels of miR-148a-3p were artificially regulated with miR-148a-3p mimics and the miR-148a-3p inhibitor. The relative expression levels of miR-148a-3p in the samples of each cell line were determined. Cell Counting Kit-8 (CCK-8) was used to detect cell proliferation, while the effect of the miR-148a-3p mimics and inhibitor on tumor cell migration was detected by wound healing assay. Flow cytometry assay was carried out to explore the effect of miR-148a-3p on cell apoptosis. Dual-luciferase reporter assay was performed in order to verify miR-148a-3p's target gene. The expressions of ROCK-1 and Bcl-2 were analyzed by western blot.

RESULTS

The relative expression of miR-148a-3p in tumor and adjacent tissues was assessed with qRT-PCR (P < 0.05) and found to be significantly lower in the tumor tissues than the adjacent tissues. The data obtained from the CCK-8 and wound healing assay showed that intracellular transfection of miR-148a-3p mimics could inhibit cell proliferation and migration, while the miR-148a-3p inhibitor promoted them. Overexpression of miR-148a-3p promoted cell apoptosis in the T24 and 5,637 cell lines. The dual-luciferase reporter assay verified that ROCK-1 is a direct target of miR-148a-3p. Western blot showed that miR-148a-3p overexpression downregulated the expression of ROCK-1 and Bcl-2, while miR-148a-3p knockdown upregulated the expression of ROCK-1 and Bcl-2.

CONCLUSIONS

We confirmed that miR-148a-3p was significantly decreased in bladder cancer cells. miR-148a-3p overexpression inhibited bladder cancer cell proliferation and migration, whereas miR-148a-3p knockdown promoted bladder cancer cell proliferation and migration. Moreover, we found that ROCK-1 was a downstream target of miR-148a-3p. We also found that miR-148a-3p induced cell apoptosis by regulating the expression of Bcl-2. However, the deeper mechanism of this regulatory relationship needs further study.

MicroRNAs as biomarkers for prostate cancer prognosis: a systematic review and a systematic reanalysis of public data

Background

Reliable prognostic biomarkers to distinguish indolent from aggressive prostate cancer (PCa) are lacking. Many studies investigated microRNAs (miRs) as PCa prognostic biomarkers, often reporting inconsistent findings. We present a systematic review of these; also systematic reanalysis of public miR-profile datasets to identify tissue-derived miRs prognostic of biochemical recurrence (BCR) in patients undergoing radical prostatectomy.

Methods

Independent PubMed searches were performed for relevant articles from January 2007 to December 2019. For the review, 128 studies were included. Pooled-hazard-ratios (HRs) for miRs in multiple studies were calculated using a random-effects model (REM). For the reanalysis, five studies were included and Cox proportional-hazard models, testing miR association with BCR, performed for miRs profiled in all.

Results

Systematic review identified 120 miRs as prognostic. Five (let-7b-5p, miR-145-5p, miR152-3p, miR-195-5p, miR-224-5p) were consistently associated with progression in multiple cohorts/studies. In the reanalysis, ten (let-7a-5p, miR-148a-3p, miR-203a-3p, miR-26b-5p, miR30a-3p, miR-30c-5p, miR-30e-3p, miR-374a-5p, miR-425-3p, miR-582-5p) were significantly prognostic of BCR. Of these, miR-148a-3p (HR = 0.80/95% CI = 0.68-0.94) and miR-582-5p (HR = 0.73/95% CI = 0.61-0.87) were also reported in prior publication(s) in the review.

Conclusions

Fifteen miRs were consistently associated with disease progression in multiple publications or datasets. Further research into their biological roles is warranted to support investigations into their performance as prognostic PCa biomarkers.

Deep Sequencing of the Rat MCAO Cortexes Reveals Crucial circRNAs Involved in Early Stroke Events and Their Regulatory Networks

Circular RNAs (circRNAs) are highly enriched in the central nervous system and significantly involved in a range of brain-related physiological and pathological processes. Ischemic stroke is a complex disorder caused by multiple factors; however, whether brain-derived circRNAs participate in the complex regulatory networks involved in stroke pathogenesis remains unknown. Here, we successfully constructed a cerebral ischemia-injury model of middle cerebral artery occlusion (MCAO) in male Sprague-Dawley rats. Preliminary qualitative and quantitative analyses of poststroke cortical circRNAs were performed through deep sequencing, and RT-PCR and qRT-PCR were used for validation. Of the 24,858 circRNAs expressed in the rat cerebral cortex, 294 circRNAs were differentially expressed in the ipsilateral cerebral cortex between the MCAO and sham rat groups. Cluster, GO, and KEGG analyses showed enrichments of these circRNAs and their host genes in numerous biological processes and pathways closely related to stroke. We selected 106 of the 294 circRNAs and constructed a circRNA-miRNA-mRNA interaction network comprising 577 sponge miRNAs and 696 target mRNAs. In total, 15 key potential circRNAs were predicted to be involved in the posttranscriptional regulation of a series of downstream target genes, which are widely implicated in poststroke processes, such as oxidative stress, apoptosis, inflammatory response, and nerve regeneration, through the competing endogenous RNA mechanism. Thus, circRNAs appear to be involved in multilevel actions that regulate the vast network of multiple mechanisms and events that occur after a stroke. These results provide novel insights into the complex pathophysiological mechanisms of stroke.

Crosstalk between miRNAs and signaling pathways involved in pancreatic cancer and pancreatic ductal adenocarcinoma

Pancreatic cancer (PC) is the seventh leading cause of cancer-related deaths worldwide with 5-year survival rates below 8%. Most patients with PC and pancreatic ductal adenocarcinoma (PDAC) die after relapse and cancer progression as well as resistance to treatment. Pancreatic tumors contain a high desmoplastic stroma that forms a rigid mass and has a potential role in tumor growth and metastasis. PC initiates from intraepithelial neoplasia lesions leading to invasive cancer through various pathways. These lesions harbor particular changes in signaling pathways involved in the tumorigenesis process. These events affect both the epithelial cells, including the tumor and the surrounding stroma, and eventually lead to the formation of complex signaling networks. Genetic studies of PC have revealed common molecular features such as the presence of mutations in KRAS gene in more than 90% of patients, as well as the inactivation or deletion mutations of some tumor suppressor genes including TP53, CDKN2A, and SMAD4. In recent years, studies have also identified different roles of microRNAs in PC pathogenesis as well as their importance in PC diagnosis and treatment, and their involvement in various signaling pathways. In this study, we discussed the most common pathways involved in PC and PDAC as well as their role in tumorigenesis and progression. Furthermore, the miRNAs participating in the regulation of these signaling pathways in PC progression are summarized in this study. Therefore, understanding more about pathways involved in PC can help with the development of new and effective therapies in the future.

A Multiomics Graph Database System for Biological Data Integration and Cancer Informatics

The multiomics data are heterogeneous and come from different biological levels such as epigenetics, genomics, transcriptomics and proteomics. The development of high-throughput technologies has enabled researchers not only to study all the entities together but also to utilize information from different levels spanning DNA methylation, copy number variation (CNV), mutation, gene expression, and miRNA expression. With the recent advancement in image informatics, the field of radiomics is rapidly emerging. It can be expected that the information from microscopic images of the tissue will soon be part of many multiomics studies. Meanwhile, integration of different kinds of multiomics data to extract relevant biological information is currently a big challenge. This study is our ongoing effort to develop a model that properly integrates multiomics data and allows easy retrieval of information relevant to biological processes. In this article, we have enriched our previous graph database model to store gene expression, miRNA expression, DNA methylation, mutation, CNV, clinical data, including information of the image of tissue slides. To show that the model is working, we used data from the Cancer Genome Atlas for three cancer types.

Non-coding RNAs in Pancreatic Ductal Adenocarcinoma

Non-coding RNAs (ncRNAs) are reported to be expressed in human cancers, including pancreatic ductal adenocarcinoma (PDAC). These ncRNAs affect the growth, migration and invasion of tumor cells by regulating cell cycle and apoptosis, as well as playing important roles in epigenetic processes, transcription and post-transcriptional regulation. It is still unclear whether alterations in ncRNAs influence PDAC development and progression. Because of this, analysis based on existing data on ncRNAs, which are crucial for modulating pancreatic tumorigenesis, will be important for future research on PDAC. Here, we summarize ncRNAs with tumor-promoting functions: HOTAIR, HOTTIP, MALAT1, lncRNA H19, lncRNA PVT1, circ-RNA ciRS-7, circ-0030235, circ-RNA_100782, circ-LDLRAD3, circ-0007534, circRHOT1, circZMYM2, circ-IARS, circ-RNA PDE8A, miR-21, miR-155, miR-221/222, miR-196b, miR-10a. While others including GAS5, MEG3, and lncRNA ENST00000480739, has_circ_0001649, miR-34a, miR-100, miR-217, miR-143 inhibit the proliferation and invasion of PDAC. Hence, we summarize the functions of ncRNAs in the occurrence, development and metastasis of PDAC, with the goal to provide guidance in the clinical diagnosis and treatment of PDAC.

Let-7b-5p promotes electroacupuncture tolerance by downregulating Penk1 gene in CFA-induced inflammatory nociception rats

BACKGROUND

Studies showed that increased let-7b-5p microRNA during repeated electroacupuncture (EA) treatment was associated the formation of EA tolerance, which manifested as gradually decreased nociceptive threshold. Proenkephalin (PENK) is the precursor of enkephalin which is a pivot neuropeptide responsible for the decreased nociceptive threshold in EA. The aim of this study was to evaluate the relationship between let-7b-5p and PENK in EA tolerance.

METHODS

The target gene of let-7b-5p microRNA was determined through the dual-luciferase reporter assay in cortical neurons. Seventy-two Sprague Dawley rats received a combination of EA and intracerebroventricular injection of microRNA (let-7b-5p agomir, antagomir or their controls). The nociceptive thresholds were assessed with radiant heat tail-flick method. PENK and let-7b-5p were measured with Western Blot and qPCR, respectively, after administration of let-7b-5p agomir, antagomir, and their controls at day 1, 4 and 7.

RESULTS

Let-7b-5p targeted the 3' untranslated region of Penk1. The nociceptive thresholds in Let-7b-5p agomir + EA group were decreased (p < 0.05) compared with those in Let-7b-5p antagomir + EA group at day 1 to 7. Compared with Let-7b-5p agomir + EA group, the expression level of PENK in Let-7b-5p antagomir + EA group was increased at days 1, 4, and 7 (p < 0.05) CONCLUSION: Let-7b-5p may be a new potential target for decreasing the EA tolerance effect and facilitating the application of EA in treating chronic nociception of patients.

miR-148a regulates expression of the transferrin receptor 1 in hepatocellular carcinoma

Transferrin receptor 1 (TFR1) is a transmembrane glycoprotein that allows for transferrin-bound iron uptake in mammalian cells. It is overexpressed in various cancers to satisfy the high iron demand of fast proliferating cells. Here we show that in hepatocellular carcinoma (HCC) TFR1 expression is regulated by miR-148a. Within the TFR1 3′UTR we identified and experimentally validated two evolutionarily conserved miRNA response elements (MREs) for miR-148/152 family members, including miR-148a. Interestingly, analyses of RNA sequencing data from patients with liver hepatocellular carcinoma (LIHC) revealed a significant inverse correlation of TFR1 mRNA levels and miR-148a. In addition, TFR1 mRNA levels were significantly increased in the tumor compared to matched normal healthy tissue, while miR-148a levels are decreased. Functional analysis demonstrated post-transcriptional regulation of TFR1 by miR-148a in HCC cells as well as decreased HCC cell proliferation upon either miR-148a overexpression or TFR1 knockdown. We hypothesize that decreased expression of miR-148a in HCC may elevate transferrin-bound iron uptake, increasing cellular iron levels and cell proliferation.

Complex role of miR-130a-3p and miR-148a-3p balance on drug resistance and tumor biology in esophageal squamous cell carcinoma

miRNAs play a crucial role in cancer development and progression. However, results on the impact of miRNAs on drug sensitivity and tumor biology vary, and most studies to date focussed on either increasing or decreasing miRNA expression levels. Therefore, the current study investigated the role of different expression levels of miR-130a-3p and miR-148a-3p on drug resistance and tumor biology in four esophageal squamous cell carcinoma cell lines. Interestingly, up- and downregulation of both miRNAs significantly increased sensitivity towards chemotherapy. MiRNA modulation also reduced adherence and migration potential, and increased apoptosis rates. Target analyses showed that up- and downregulation of both miRNAs activated the apoptotic p53-pathway via increased expression of either BAX (miR-148a-3p) or Caspase 9 (miR-130a-3p). miR-148a-3p downregulation seemed to mediate its effects primarily via regulation of Bim rather than Bcl-2 levels, whereas we found the opposite scenario following miR-148a-3p upregulation. A similar effect was observed for miR-130a-3p regulating Bcl-2 and XIAP. Our data provide the first evidence that miRNA modulation in both directions may lead to similar effects on chemotherapy response and tumor biology in esophageal squamous cell carcinoma. Most interestingly, up- and downregulation seem to mediate their effects via modulating the balance of several validated or predicted targets.

MicroRNAs in pancreatic cancer diagnosis and therapy

Pancreatic cancer remains a disease with very poor prognosis (only 5-6% of patients are still alive after five years). Attempts to improve the results of treatment of pancreatic cancer focus on a better understanding of the pathogenesis, and non-invasive diagnostic methods (genetic testing from peripheral blood), which would create the possibility of early diagnosis and early surgical treatment before the onset of metastasis. New hopes for the improvement of early diagnosis and treatment of pancreatic ductal adenocarcinoma (PDAC) are associated with genetic testing of microRNA expression changes. A large body of evidence has revealed that microRNAs are aberrantly expressed in the serum and in cancer tissues and elicit oncogenic or tumour-suppressive functions. Selected microRNAs can distinguish pancreatic ductal adenocarcinoma from non-cancerous lesions of the pancreas. This review focuses on the involvement of microRNAs in the early diagnosis of pancreatic cancer. Research results related to the development of a novel therapeutic strategy based on the modulation of microRNA expressions for a better outcome in patients with pancreatic cancer are also presented.

Clinical Impact of Epithelial-to-Mesenchymal Transition Regulating MicroRNAs in Pancreatic Ductal Adenocarcinoma

Pancreatic ductal adenocarcinoma (PDAC) is one of the most aggressive carcinoma entities worldwide with early and rapid dissemination. Recently, we discussed the role of microRNAs as epigenetic regulators of Epithelial-to-Mesenchymal Transition (EMT) in PDAC. In this study, we investigated their value as diagnostic and prognostic markers in tissue and blood samples of 185 patients including PDAC, non-malignant pancreatic disorders, and age-matched healthy controls. Expression of the microRNA-200-family (microRNAs -141, -200a, -200b, -200c, -429) and microRNA-148a was significantly downregulated in tissue of PDAC Union internationale contre le cancer (UICC) Stage II. Correspondingly, stromal PDAC tissue showed strong expression of Fibronectin, Vimentin, and ZEB-1 (Zinc finger E-box-binding homeobox) versus low expression of E-cadherin. Transient transfection of microRNA-200b and microRNA-200c mimics resulted in the downregulation of their key target ZEB-1. Inversely, blood serum analyses of patients with PDAC UICC Stages II, III, and IV showed a significant over-expression of microRNA-200-family members, microRNA-148a, microRNA-10b, and microRNA-34a. Correspondingly, Enzyme-linked Immunosorbent Assay (ELISA) analyses revealed a significant over-expression of soluble E-cadherin in serum samples of PDAC patients versus healthy controls. The best diagnostic accuracy to distinguish between PDAC and non-PDAC in this patient collective could be achieved in tissue by microRNA-148a with an area under the receiver-operating-characteristic (ROC) curve (AUC) of 0.885 and in blood serum by a panel of microRNA-141, -200b, -200c, and CA.19-9 with an AUC of 0.890. Both diagnostic tools outreach the diagnostic performance of the currently most common diagnostic biomarker CA.19-9 (AUC of 0.834). Kaplan Meier survival analysis of this patient collective revealed an improved overall survival in PDAC patients with high expression of tissue-related microRNA-34a, -141, -200b, -200c, and -429. In conclusion, EMT-regulating microRNAs have great potential as liquid and solid biopsy markers in PDAC patients. Their prognostic and therapeutic benefits remain important tasks for future studies.

Quantitative proteomic analysis of the miR-148a-associated mechanisms of metastasis in non-small cell lung cancer

MicroRNAs (miRs) are small non-coding RNAs that regulate gene expression and protein synthesis. Our previous study demonstrated that miR-148a suppressed the metastasis of non-small cell lung cancer (NSCLC) in vitro and in vivo. However, the modulatory mechanism of this effect remains unclear. In the present study, quantitative proteomic technology was used to study the protein expression profile of SPC-A-1 cells subsequent to the downregulation of miR-148a expression, in order to elucidate the molecular mechanism of the suppression of NSCLC metastasis by miR-148a. The differentially expressed proteins identified were analyzed using bioinformatics tools, including the Database for Annotation, Visualization and Integrated Discovery and the Search Tool for the Retrieval of Interacting Genes/proteins. In two experiments, 4,048 and 4,083 proteins were identified, and 4,014 and 4,039 proteins were quantified, respectively. In total, 44 proteins were upregulated and 40 proteins were downregulated. This was verified at the protein and mRNA levels by western blotting and reverse transcription-quantitative polymerase chain reaction, respectively. Bioinformatics analysis was used to identify potential interactions and signaling networks for the differentially expressed proteins. This may have provided an appropriate perspective for the comprehensive analysis of the modulatory mechanism underlying the metastasis-suppressive effects of miR-148a in NSCLC. In conclusion, quantitative proteomic technology revealed that miR-148a may regulate a panel of tumor-associated proteins to suppress metastasis in NSCLC.

MEF2‑activated long non‑coding RNA PCGEM1 promotes cell proliferation in hormone‑refractory prostate cancer through downregulation of miR‑148a

Prostate cancer gene expression marker 1 (PCGEM1) is a prostate-specific gene overexpressed in prostate cancer cells that promotes cell proliferation. To study the molecular mechanism of PCGEM1 function in hormone-refractory prostate cancer, the interaction between myocyte enhancer factor 2 (MEF2) and PCGEM1 was assessed by a luciferase reporter assay and chromatin immunoprecipitation (ChIP) assay. In addition, the underlying mechanism of PCGEM1 regulating expression of microRNA (miR)-148a in PC3 prostate cancer cells was evaluated. Relative expression levels were measured by reverse transcription-quantitative polymerase chain reaction, and early apoptosis was measured by flow cytometry. PCGEM1 was demonstrated to be overexpressed in prostate cancer tissues compared with noncancerous tissues. Expression levels of PCGEM1 in PC3 cancer cells were demonstrated to be regulated by MEF2, as PCGME1 mRNA was increased by MEF2 overexpression but decreased by MEF2 silencing. MEF2 was also demonstrated to enhance the activity of PCGEM1 promoter and thus promote PCGEM1 transcription. In addition, downregulation of PCGEM1 expression in PC3 cells increased expression of miR-148a. By contrast, overexpression of PCGEM1 decreased miR-148a expression. Finally, PCGME1 silencing by small interfering RNA significantly induced early cell apoptosis but this effect was reduced by a miR-148a inhibitor. In conclusion, the present study demonstrated a positive regulatory association between MEF2 and PCGEM1, and a reciprocal negative regulatory association between PCGEM1 and miR-148a that controls cell apoptosis. The present study, therefore, provides new insights into the mechanism of PCGEM1 function in prostate cancer development.

Complex Epigenetic Regulation of Chemotherapy Resistance and Biohlogy in Esophageal Squamous Cell Carcinoma via MicroRNAs

Background: Resistance towards chemotherapy is a major obstacle in the treatment of esophageal squamous cell carcinoma (ESCC). We investigated the role of specific microRNAs in chemotherapy resistance and tumor biology. Methods: We selected three microRNAs from characteristic microRNA signatures of resistant ESCC (hsa-miR-125a-5p, hsa-miR-130a-3p, hsa-miR-1226-3p), and hsa-miR-148a-3p. Effects on chemotherapy, adhesion, migration, apoptosis and cell cycle were assessed in six ESCC cell lines. Target analyses were performed using Western blotting and luciferase techniques. Results: MiR-130a-3p sensitized cells towards cisplatin in 100% of cell lines, miR-148a-3p in 83%, miR-125a-5p in 67%, miR-1226-3p in 50% (p ≤ 0.04). MiR-130a-3p sensitized 83% of cell lines towards 5-FU, miR-148a-3p/miR-125a-5p/miR-1226-3p only 33% (p ≤ 0.015). Several resistance-relevant pathways seem to be targeted on various levels. Bcl-2 was confirmed as a direct target of miR-130a-3p and miR-148a-3p, and p53 as a target of miR-125a-5p. All microRNAs decreased migration and adhesion, except miR-130a-3p, and increased apoptosis. Simultaneous manipulation of two microRNAs exhibited additive sensitizing effects towards cisplatin in 50% (miR-125a-5p/miR-148a-3p), and 75% (miR-148a-3p/miR-130a-3p) of cell lines (p ≤ 0.006). Conclusion: Our data present strong evidence that specific microRNA signatures are responsible for drug resistance and aggressiveness of ESCC. Final functional readout of these complex processes appears to be more important than single microRNA-target interactions.

Deciphering microRNA targets in pancreatic cancer using miRComb R package

MiRNAs are small non-coding RNAs that post-transcriptionally regulate gene expression. They play important roles in cancer but little is known about the specific functions that each miRNA exerts in each type of cancer. More knowledge about their specific targets is needed to better understand the complexity of molecular networks taking part in cancer. In this study we report the miRNA-mRNA interactome occurring in pancreatic cancer by using a bioinformatic approach called miRComb, which combines tissue expression data with miRNA-target prediction databases (TargetScan, miRSVR and miRDB). MiRNome and transcriptome of 12 human pancreatic tissues (9 pancreatic ductal adenocarcinomas and 3 controls) were analyzed by next-generation sequencing and microarray, respectively. Analysis confirmed differential expression of both miRNAs and mRNAs in cancerous tissue versus control, and unveiled 17401 relevant miRNA-mRNA interactions likely to occur in pancreatic cancer. They were sorted according to the degree of negative correlation between miRNA and mRNA expression. Results highlighted the importance of miR-148a and miR-21 interactions among others. Two components of the Notch signaling pathway, ADAM17 and EP300, were confirmed as miR-148a targets in MiaPaca-2 pancreatic cancer cells overexpressing miR-148a. Moreover, a CRISPR-Cas9 cellular model was generated to knock-out the expression of miR-21 in PANC-1 cells. As expected, the expression of two miRComb miR-21 predicted targets, PDCD4 and BTG2, was significantly upregulated in these cells in comparison to control PANC-1.

MicroRNA-148a promotes apoptosis and suppresses growth of breast cancer cells by targeting B-cell lymphoma 2

MicroRNAs (miRNAs) contribute toward tumorigenesis through the modulation of tumor-related genes. MiR-148a has been characterized as a tumor-suppressing miRNA and its downregulation has been reported in tumors of a variety of cancers. However, the functional role of miR-148a in breast cancer is not yet fully understood. Using both in-vitro and in-vivo models, we confirmed that miR-148a acts to inhibit the proliferation of breast cancer cells. Through the use of bioinformatic approaches in miRNA target prediction, we determined that B-cell lymphoma 2 (BCL-2) is a likely target of miR-148a. The overexpression and tumorigenic effects of BCL-2 have already been confirmed in cancerous tumors of the breast. A dual-luciferase assay was performed to confirm that miR-148a targets the 3'-untranslated region of BCL-2. In this study, we first characterized the downregulation of miR-148a in breast cancer tissues. We then found that restoring expression of miR-148a suppressed the expression of BCL-2 at the level of both mRNA and protein. Upregulation of miR-148a caused a subsequent reduction of proliferation and an increase in apoptosis. In conclusion, we have confirmed the role of miR-148a as a pivotal regulator in breast cancer through its targeting of BCL-2. This evidence strongly suggests that miR-148a could prove to be a novel therapeutic target in breast cancer.

Gene expression meta-analysis in diffuse low-grade glioma and the corresponding histological subtypes

Diffuse low-grade glioma (DLGG) is a well-differentiated, slow-growing tumour with an inherent tendency to progress to high-grade glioma. The potential roles of genetic alterations in DLGG development have not yet been fully delineated. Therefore, the current study performed an integrated gene expression meta-analysis of eight independent, publicly available microarray datasets including 291 DLGGs and 83 non-glioma (NG) samples to identify gene expression signatures associated with DLGG. Using INMEX, 708 differentially expressed genes (DEGs) (385 upregulated and 323 downregulated genes) were identified in DLGG compared to NG. Furthermore, 497 DEGs (222 upregulated and 275 downregulated genes) corresponding to two histological types were identified. Of these, high expression of HIP1R significantly correlated with increased overall survival, whereas high expression of TBXAS1 significantly correlated with decreased overall survival. Additionally, network-based meta-analysis identified FN1 and APP as the key hub genes in DLGG compared with NG. PTPN6 and CUL3 were the key hub genes identified in the astrocytoma relative to the oligodendroglioma. Further immunohistochemical validation revealed that MTHFD2 and SPARC were positively expressed in DLGG, whereas RBP4 was positively expressed in NG. These findings reveal potential molecular biomarkers for diagnosis and therapy in patients with DLGG and provide a rich and novel candidate reservoir for future studies.

Cancer Hallmarks and MicroRNAs: The Therapeutic Connection

Human cancers are characterized by a number of hallmarks, including sustained proliferative signaling, evasion of growth suppressors, activated invasion and metastasis, replicative immortality, angiogenesis, resistance to cell death, and evasion of immune destruction. As microRNAs (miRNAs) are deregulated in virtually all human cancers, they show involvement in each of the cancer hallmarks as well. In this chapter, we describe the involvement of miRNAs in cancer from a cancer hallmarks and targeted therapeutics point of view. As no miRNA-based cancer therapeutics are available to date, and the only clinical trial on miRNA-based cancer therapeutics (MRX34) was terminated prematurely due to serious adverse events, we are focusing on protein-coding miRNA targets for which targeted therapeutics in oncology are already approved by the FDA. For each of the cancer hallmarks, we selected major protein-coding players and describe the miRNAs that target them.

MicroRNA-148a suppresses epithelial-mesenchymal transition and invasion of pancreatic cancer cells by targeting Wnt10b and inhibiting the Wnt/β-catenin signaling pathway

Epithelial-mesenchymal transition (EMT) plays a critical role in the process of cancer invasion and metastasis. The Wnt/β-catenin signaling pathway is known as a stimulative factor, which may trigger EMT and metastasis of cancer cells. In addition, several microRNAs (miRNAs) have been proven to regulate the EMT process. Recent research revealed that miR‑148a is downregulated in pancreatic cancer. However, the definite role of miR-148a in EMT and invasion of pancreatic cancer is still unknown. The present study attempted to demonstrate the underlying mechanism of miR-148a in the regulation of EMT and invasion of pancreatic cancer cells. Our data revealed that the expression of miR-148a was markedly downregulated in human pancreatic ductal adenocarcinoma (PDAC) cell lines and tissues. In addition, the downregulation of miR-148a was associated with poor prognosis and EMT phenotype. Furthermore, restoration of miR-148a expression inhibited the EMT process, as well as the migration and invasion of BxPC-3 pancreatic cancer cells. Wnt10b, a promoting molecule of the Wnt/β-catenin signaling pathway, was demonstrated by dual‑luciferase reporter assay to be a direct target of miR‑148a. Subsequently, we found that miR‑148a negatively regulated the protein expression of β-catenin, cyclin D1 and MMP-9, which were important components of the Wnt/β-catenin signaling pathway. In conclusion, these findings revealed that miR-148a suppresses EMT and invasion of pancreatic cancer cells by targeting Wnt10b and inhibiting the Wnt/β-catenin signaling pathway, and thus, miR-148a may serve as a novel therapeutic target for pancreatic cancer.

MicroRNA-1225-5p inhibits proliferation and metastasis of gastric carcinoma through repressing insulin receptor substrate-1 and activation of β-catenin signaling

Emerging evidence has linked aberrantly expressed microRNAs (miRNAs) with oncogenesis and malignant development in various human cancers. However, their specific roles and functions in gastric carcinoma (GC) remain largely undefined. In this study we identify and report a novel miRNA, miR-1225-5p, as tumor suppressor in GC development and progression. Microarray analysis revealed that there were fifty-six differentially expressed miRNAs (thirty-two upregulated and twenty-four downregulated) in GC tumor samples compared to their corresponding nontumorous tissues. Downregulation of miR-1225-5p was frequently detected in GC and strongly correlated with more aggressive phenotypes and poor prognosis. Functional assays demonstrated that ectopic overexpression of miR-1225-5p could inhibit cell proliferation, colony formation, migration and invasion in vitro, as well as suppress tumor growth and metastasis in nude mice. Further integrative and functional studies suggested insulin receptor substrate 1 (IRS1) as a downstream effector of miR-1225-5p which acted through β-catenin signaling pathway. These results demonstrate that miR-1225-5p serves to constrain GC growth and metastatic potential via inhibition of IRS1 and β-catenin signaling. Therefore, downregulation of miR-1225-5p is likely to be one of major molecular mechanisms accounting for the development and progression of GC.

The Role of Mir-148a in Cancer

MicroRNAs (miRNAs) are highly conserved noncoding RNAs of about 19-25 nucleotides. Through specifically pairing with complementary sites in 3' untranslated regions (UTRs) of target mRNAs, they mediate post-transcriptional silencing. MicroRNAs have been implicated in many physiological processes including proliferation, differentiation, development, apoptosis, and metabolism. In recent years many studies have revealed that the aberrant expression of miRNA is closely related to oncogenesis and is now an intense field of study. Mir-148a is aberrantly expressed in various cancers and has been identified as an oncogenic or tumor suppressor with crucial roles in the molecular mechanisms of oncogenesis. In this review, we have summarized the role of mir-148a in the oncogenic pathways of gastric, liver, breast and urogenital cancers, and in neurogliocytoma oncogenesis. Studying the functional role of mir-148a is crucial in discovering novel tumor molecular markers and identifying potential therapeutic targets.

Managing Pancreatic Adenocarcinoma: A Special Focus in MicroRNA Gene Therapy

Pancreatic cancer is an aggressive disease and the fourth most lethal cancer in developed countries. Despite all progress in medicine and in understanding the molecular mechanisms of carcinogenesis, pancreatic cancer still has a poor prognosis, the median survival after diagnosis being around 3 to 6 months and the survival rate of 5 years being less than 4%. For pancreatic ductal adenocarcinoma (PDAC), which represents more than 90% of new pancreatic cancer cases, the prognosis is worse than for the other cancers with a patient mortality of approximately 99%. Therefore, there is a pressing need for developing new and efficient therapeutic strategies for pancreatic cancer. In this regard, microRNAs not only have been seen as potential diagnostic and prognostic molecular markers but also as promising therapeutic agents. In this context, this review provides an examination of the most frequently deregulated microRNAs (miRNAs) in PDAC and their putative molecular targets involved in the signaling pathways of pancreatic
carcinogenesis. Additionally, it is presented a summary of gene therapy clinical trials involving miRNAs and it is illustrated the therapeutic potential associated to these small non-coding RNAs, for PDAC treatment. The facts presented here constitute a strong evidence of the remarkable opportunity associated to the application of microRNA-based therapeutic strategies as a novel approach for cancer therapy.

Regulation of expression of microRNAs by DNA methylation in lung cancer

Differential expression of miRNAs has been linked with lung carcinogenesis. Recent studies have indicated that DNA hypermethylation can lead to silencing of tumor suppressor miRNA-encoding genes. Restoration of tumor suppressor miRNAs using inhibitors of DNA methyltransferases has been shown to suppress cell proliferation, angiogenesis, invasion and metastasis implying that modulation of methylation of specific miRNAs can be used as novel therapeutic targets in lung cancer. In this review, we highlight tremendous progress which has been made in the identification of methylation-mediated silencing of miRNAs and their contribution in lung carcinogenesis along with the clinical utility of methylated miRNAs.

The potential function of microRNA in chordomas

Little is known about the molecular biology of chordomas, which are rare, chemoresistant tumors with no well-established treatment. miRNAs regulate gene networks and pathways. We aimed to evaluate the effects of dysregulated miRNA in chordomas would help reveal the underlying mechanisms of chordoma initiation and progression. In this study, miR-31, anti-miR-140-3p, anti-miR148a, and miR-222 were transiently transfected to chordoma cell lines and an MTS assay, apoptosis assay, and cell-cycle analysis were conducted to evaluate the effects. The mRNA level of predicted and confirmed targets of each miRNA, as well as the EMT and MET markers of U-CH1 and MUG-Chor1, were assessed with real-time polymerase chain reaction. Transient transfection of miRNA mimics was achieved, as each mimic increased or decreased the level of its corresponding miRNA. miR-31 decreased cell viability in MUG-Chor1 and U-CH2 after 72h, which is consistent with previous findings for U-CH1. Both miR-31 and anti-miR-148a induced apoptosis in all three cell lines. Although each miRNA had a similar pattern, miR-31 had the most effective S-phase arrest in all three cell lines. RDX, MET, DNMT1, DNMT3B, TRPS1, BIRC5, and KIT were found to be targeted by the selected miRNAs. The level of miR-222 in chordoma cell lines U-CH1 and MUG-Chor1 correlated positively with EMT markers and negatively with MET markers. This study uncovered the potential of miR-31, miR-140-3p, miR-148a, and miR-222-3p to be key molecules in the cell viability, cell cycle, and apoptosis in chordomas, as well as initiation, differentiation, and progression.

MiRNAs are involved in chronic electroacupuncture tolerance in the rat hypothalamus

Acupuncture tolerance is the gradual decrease in analgesic effect due to its prolonged application. However, its mechanism in terms of miRNA is still unknown. To explore the role of miRNAs in electroacupuncture (EA) tolerance of rats using deep sequencing, rats with more than a 50 % increase in tail flick latency (TFL) in response to EA were selected for this experiment. EA tolerance was induced by EA once daily for eight consecutive days. The hypothalami were harvested for deep sequencing. As a result, 49 differentially expressed miRNAs were identified and validated by real-time PCR. Of them, let-7b-5p, miR-148a-3p, miR-124-3p, miR-107-3p, and miR-370-3p were further confirmed to be related to EA tolerance by an intracerebroventricular injection of agomirs or antagomirs of these miRNAs. Potential targets of the 49 miRNAs were enriched in 9 pathways and 282 gene ontology (GO) terms. Five miRNAs were confirmed to participate in EA tolerance probably through the functional categories related to nerve impulse transmission, receptor signal pathways, and gene expression regulation, as well as pathways related to MAPK, neurotrophin, fatty acid metabolism, lysosome, and the degradation of valine, leucine, and isoleucine. Our findings reveal a characterized panel of the differentially expressed miRNAs in the hypothalamus in response to EA and thus provide a solid experimental framework for future analysis of the mechanisms underlying EA-induced tolerance.

MicroRNA-148a represents an independent prognostic marker in bladder cancer

A previous study has demonstrated the roles of microRNA-148a (miR-148a) on apoptosis of bladder cancer cells. The goal of this study was to investigate whether the miR-148a expression level could serve as a new biomarker for the prognosis of bladder cancer patients. We collected a total of 126 bladder cancer samples. The expression level of miR-148a was determined with quantitative real-time polymerase chain reaction (qRT-PCR). Kaplan-Meier method was used to analyze the overall survival. Cox regression analysis was further used to identify prognostic factors. The expression levels of miR-148a in bladder cancer tissues were identified (1.5 ± 0.3; P < 0.001). The bladder cancer patients in the low-expression group more frequently had a high tumor grade (P = 0.025), increased tumor recurrence (P = 0.002), and advanced lymph node (LN) metastasis (P = 0.001). Patient survival analysis revealed a clear positive correlation between miR-148a expression level and survival time of bladder cancer patients (P = 0.005, log-rank = 7.714). In univariate Cox proportional hazards regression analysis, we found that a low-expression level of miR-148a (P = 0.018), tumor grade (P = 0.006), lymph node metastasis (P = 0.001), and recurrence (P < 0.001) were associated with the prognosis of bladder cancer. In multivariate analysis, we found that miR-148a expression (RR = 0.206, 95 % CI 0.095-0.813, P = 0.029), tumor grade (RR = 0.714, 95 % CI 0.224-0.958, P = 0.714), lymph node metastasis (RR = 6.604, 95 % CI 3.192-12.547, P < 0.001), and recurrence (RR = 15.126, 95 % CI 6.714-22.025, P < 0.001) retained significance as an independent prognostic factor of bladder cancer survival (Table 3). All results have showed that miR-148a expression was decreased in bladder cancer specimens and reduced miR-148a expression was associated with poorer survival time, indicating that miR-148a may become a candidate factor for predicting the prognosis of bladder cancer.

MicroRNA-148a inhibits breast cancer migration and invasion by directly targeting WNT-1

Wnt/β-catenin signaling pathway influences embryonic development, cell polarity and adhesion, apoptosis and tumorigenesis. MicroRNAs (miRNAs) function as important regulators of the tumorigenesis and metastasis. In the present study, we aimed to find novel targets and mechanisms of microRNA-148a (miR-148a) in regulating the migration and invasion of breast cancer cells. In the present study, miR-148a was found downregulated in human breast cancer tissues and cell lines. The ectopic miR-148a expression inhibited the migration and invasion of MCF-7 and MDA-MB-231 breast cancer cells. Furthermore, we demonstrated that WNT-1, one of the ligands of Wnt/β-catenin signaling pathway, was a direct target of miR-148a. The overexpression of miR-148a reduced the mRNA and protein expression levels of WNT-1, also decreased the expression levels of the key components of Wnt/β-catenin pathway, including β-catenin, metalloproteinase-7 (MMP-7) and T-cell factor-4 (TCF-4) in MCF-7 and MDA-MB-231 cells. In addition, the data showed that the expression of WNT-1 was significantly higher in human breast cancer tissues compared with the adjacent normal tissues and the expression of miR-148a was negatively correlated with the WNT-1 expression in human breast cancer tissues. Taken together, our results suggest that miR-148a can suppress the migration and invasion of breast cancer cells by targeting WNT-1 and inhibiting Wnt/β-catenin signaling pathway and this will provide new insights into the molecular mechanisms of breast cancer metastasis.

Small nucleolar RNA U91 is a new internal control for accurate microRNAs quantification in pancreatic cancer

BACKGROUND

RT-qPCR quantification of miRNAs expression may play an essential role in pancreatic ductal adenocarcinoma (PDAC) diagnostics. RT-qPCR-based experiments require endogenous controls for the result normalization and reliability. However, expression instability of reference genes in tumors may introduce bias when determining miRNA levels.

METHODS

We investigated expression of 6 miRNAs, isolated from FFPE samples of pancreatic adenocarcinomas. Four internal controls were utilized for RT-qPCR result normalization: artificial miR-39 from C. elegans, U6 snRNA, miR-16 and snoRNA U91.

RESULTS

We found miR-21, miR-155 or miR-217 expression values in tumors may differ up to several times, depending on selected internal controls. Moreover, different internal controls can produce controversial results for miR-96, miR-148a or miR-196a quantification. Also, expression of our endogenous controls varied significantly in tumors. U6 demonstrated variation from -1.03 to 8.12-fold, miR-16 from -2.94 up to 7.38-fold and the U91 from -3.05 to 4.36-fold respectively. On the other hand, the most stable gene, determined by NormFinder algorithm, was U91. Each miRNA normalized relatively to the spike or U91, demonstrated similar expression values. Thus, statistically significant and insignificant differences between tumors and normal tissues for miRNAs were equal for the spike and the U91. Also, the differences between the spike and U91 were statistically insignificant for all of miRs except miR-217. Among three endogenous controls, U91 had the lowest average expression values and standard deviation in cancer tissues.

CONCLUSIONS

We recommend U91 as a new normalizer for miRNA quantification in PDACs.

Regulatory circuit of PKM2/NF-κB/miR-148a/152-modulated tumor angiogenesis and cancer progression

Upregulation of the embryonic M2 isoform of pyruvate kinase (PKM2) emerges as a critical player in the cancer development and metabolism, yet the underlying mechanism of PKM2 overexpression remains to be elucidated. Here we demonstrate that IGF-1/IGF-IR regulates PKM2 expression by enhancing HIF-1α-p65 complex binding to PKM2 promoter. PKM2 expression is regulated by miR-148a/152 suppression. PKM2 directly interacts with NF-κB p65 subunit to promote EGR1 expression for regulating miR-148a/152 feedback circuit in normal cells, but not in cancer cells because of the DNA hypermethylation of miR-148a and miR-152 gene promoters. The silencing of miR-148a/152 contributes to the overexpression of PKM2, NF-κB or/and IGF-IR in some cancer cells. We show that disruption of PKM2/NF-κB/miR-148a/152 feedback loop can regulate cancer cell growth and angiogenesis, and is also associated with triple-negative breast cancer (TNBC) phenotype, which may have clinical implication for providing novel biomarker(s) of TNBC and potential therapeutic target(s) in the future.

MicroRNA-148a inhibits migration of breast cancer cells by targeting MMP-13

Breast cancer is a threat to the health of women, and metastasis of breast cancer cells plays an important role in the deterioration of breast cancer. MicroRNAs play a critical role in the tumorigenesis and development of breast cancer. MicroRNA-148a (miR-148a) is associated with the growth and metastasis of tumor cells. In the present study, we investigated the role of miR-148a in migration of breast cancer cells as well as the underlying mechanism. MiR-148a was found to inhibit the proliferation and migration of breast cancer cells. To further explore the mechanism through which miR-148a plays its antitumor role, matrix metalloproteinase-13 (MMP-13) was identified as a target of miR-148a by western blot and luciferase reporter assay. Moreover, silence of MMP-13 mimicked the effect of miR-148a, whereas overexpression of MMP-13 rescued the impaired migration caused by miR-148a. Our study demonstrates that miR-148a inhibits the migration of breast cancer cells by targeting MMP-13 and also lays theoretical foundation for further exploration for the function of miR-148a.

MicroRNA Signaling Pathway Network in Pancreatic Ductal Adenocarcinoma

Pancreatic ductal adenocarcinoma (PDAC) is considered to be the most lethal and aggressive malignancy with high mortality and poor prognosis. Their responses to current multimodal therapeutic regimens are limited. It is urgently needed to identify the molecular mechanism underlying pancreatic oncogenesis. Twelve core signaling cascades have been established critical in PDAC tumorigenesis by governing a wide variety of cellular processes. MicroRNAs (miRNAs) are aberrantly expressed in different types of tumors and play pivotal roles as post-transcriptional regulators of gene expression. Here, we will describe how miRNAs regulate different signaling pathways that contribute to pancreatic oncogenesis and progression.

miR-148a dependent apoptosis of bladder cancer cells is mediated in part by the epigenetic modifier DNMT1

Urothelial cell carcinoma of the bladder (UCCB) is the most common form of bladder cancer and it is estimated that ~15,000 people in the United States succumbed to this disease in 2013. Bladder cancer treatment options are limited and research to understand the molecular mechanisms of this disease is needed to design novel therapeutic strategies. Recent studies have shown that microRNAs play pivotal roles in the progression of cancer. miR-148a has been shown to serve as a tumor suppressor in cancers of the prostate, colon, and liver, but its role in bladder cancer has never been elucidated. Here we show that miR-148a is down-regulated in UCCB cell lines. We demonstrate that overexpression of miR-148a leads to reduced cell viability through an increase in apoptosis rather than an inhibition of proliferation. We additionally show that miR-148a exerts this effect partially by attenuating expression of DNA methyltransferase 1 (DNMT1). Finally, our studies demonstrate that treating cells with both miR-148a and either cisplatin or doxorubicin is either additive or synergistic in causing apoptosis. These data taken together suggest that miR-148a is a tumor suppressor in UCCB and could potentially serve as a novel therapeutic for this malignancy.

MiR-148a, a microRNA upregulated in the WNT subgroup tumors, inhibits invasion and tumorigenic potential of medulloblastoma cells by targeting Neuropilin 1

Medulloblastoma, a common pediatric malignant brain tumor consists of four molecular subgroups viz. WNT, SHH, Group 3 and Group 4. MiR-148a is over-expressed in the WNT subgroup tumors, which have the lowest incidence of metastasis and excellent survival among all medulloblastomas. MiR-148a was expressed either in a transient manner using a synthetic mimic or in a stable doxycycline inducible manner using a lentiviral vector in non-WNT medulloblastoma cell lines. Expression of miR-148a to levels comparable to that in the WNT subgroup tumors was found to inhibit proliferation, clonogenic potential, invasion potential and tumorigenicity of medulloblastoma cells. MiR-148a expression in medulloblastoma cells brought about reduction in the expression of NRP1, a novel miR-148a target. Restoration of NRP1 expression in medulloblastoma cells was found to rescue the reduction in the invasion potential and tumorigenicity brought about by miR-148a expression. NRP1 is known to play role in multiple signaling pathways that promote tumor growth, invasion and metastasis. NRP1 expression in medulloblastomas was found to be associated with poor survival, with little or no expression in majority of the WNT tumors. The tumor suppressive effect of miR-148a expression accompanied by the down-regulation of NRP1 makes miR-148a an attractive therapeutic agent for the treatment of medulloblastomas.

miRNAs in pancreatic cancer: therapeutic potential, delivery challenges and strategies

Pancreatic ductal adenocarcinoma (PDAC) is a severe pancreatic malignancy and is predicted to victimize 1.5% of men and women during their lifetime (Cancer statistics: SEER stat fact sheet, National Cancer Institute, 2014). miRNAs have emerged as a promising prognostic, diagnostic and therapeutic tool to fight against pancreatic cancer. miRNAs could modulate gene expression by imperfect base-pairing with target mRNA and hence provide means to fine-tune multiple genes simultaneously and alter various signaling pathways associated with the disease. This exceptional miRNA feature has provided a paradigm shift from the conventional one drug one target concept to one drug multiple target theory. However, in vivo miRNA delivery is not fully realized due to challenges posed by this special class of therapeutic molecules, which involves thorough understanding of the biogenesis and physicochemical properties of miRNA and delivery carriers along with the pathophysiology of the PDAC. This review highlights the delivery strategies of miRNA modulators (mimic/inhibitor) in cancer with special emphasis on PDAC since successful delivery of miRNA in vivo constitutes the major challenge in clinical translation of this promising class of therapeutics.

Insights into the Role of microRNAs in Pancreatic Cancer Pathogenesis: Potential for Diagnosis, Prognosis, and Therapy

Pancreatic cancer is a highly lethal malignancy and a fourth leading cause of cancer-related death in the United States. Poor survival of pancreatic cancer patients is largely because of its asymptomatic progression to advanced stage against which no effective therapy is currently available. Over the years, we have developed significant knowledge of molecular progression of pancreatic cancer and identified several genetic and epigenetic aberrations to be involved in its etiology and aggressive behavior. In that regard, recent lines of evidence have suggested important roles of microRNAs (miRNAs/miRs) in pancreatic cancer pathogenesis. microRNAs belonging to a family of small, noncoding RNAs are able to control diverse biological processes due to their ability to regulate gene expression at the posttranscriptional level. Accordingly, dysregulation of miRNAs can lead to several disease conditions, including cancer. There is a long list of microRNAs that exhibit aberrant expression in pancreatic cancer and serve as key microplayers in its initiation, progression, metastasis, and chemoresistance. These findings have suggested that microRNAs could be exploited as novel biomarkers for diagnostic and prognostic assessments of pancreatic cancer and as targets for therapy. This book chapter describes clinical problems associated with pancreatic cancer, roles that microRNAs play in various aspects of pancreatic cancer pathogenesis, and envision opportunities for potential use of microRNAs in pancreatic cancer management.

Molecular mechanisms underlying the role of microRNAs in the chemoresistance of pancreatic cancer

Pancreatic ductal adenocarcinoma (PDAC) is an extremely severe disease where the mortality and incidence rates are almost identical. This is mainly due to late diagnosis and limited response to current treatments. The tumor macroenvironment/microenvironment have been frequently reported as the major contributors to chemoresistance in PDAC, preventing the drugs from reaching their intended site of action (i.e., the malignant duct cells). However, the recent discovery of microRNAs (miRNAs) has provided new directions for research on mechanisms underlying response to chemotherapy. Due to their tissue-/disease-specific expression and high stability in tissues and biofluids, miRNAs represent new promising diagnostic and prognostic/predictive biomarkers and therapeutic targets. Furthermore, several studies have documented that selected miRNAs, such as miR-21 and miR-34a, may influence response to chemotherapy in several tumor types, including PDAC. In this review, we summarize the current knowledge on the role of miRNAs in PDAC and recent advances in understanding their role in chemoresistance through multiple molecular mechanisms.

Aberrant MicroRNAs in Pancreatic Cancer: Researches and Clinical Implications

Pancreatic ductal adenocarcinoma (PDAC) is an aggressive malignancy with a high rate of mortality and poor prognosis. Numerous studies have proved that microRNA (miRNA) may play a vital role in a wide range of malignancies, including PDAC, and dysregulated miRNAs, including circulating miRNAs, are associated with PDAC proliferation, invasion, chemosensitivity, and radiosensitivity, as well as prognosis. Greater understanding of the roles of miRNAs in PDAC could provide insights into this disease and identify potential diagnostic markers and therapeutic targets. The current review focuses on recent advances with respect to the roles of miRNAs in PDAC and their practical value.