MicroRNAs as potential target gene in cancer gene therapy of gastrointestinal tumors

Tumor Microenvironment Remodeling in Gastrointestinal Cancer: Role of miRNAs as Biomarkers of Tumor Invasion

Gastrointestinal (GI) cancers are the most frequent neoplasm, responsible for half of all cancer-related deaths. Metastasis is the leading cause of death from GI cancer; thus, studying the processes that regulate cancer cell migration is of paramount importance for the development of new therapeutic strategies. In this review, we summarize the mechanisms adopted by cancer cells to promote cell migration and the subsequent metastasis formation by highlighting the key role that tumor microenvironment components play in deregulating cellular pathways involved in these processes. We, therefore, provide an overview of the role of different microRNAs in promoting tumor metastasis and their role as potential biomarkers for the prognosis, monitoring, and diagnosis of GI cancer patients. Finally, we relate the possible use of nutraceuticals as a new strategy for targeting numerous microRNAs and different pathways involved in GI tumor invasiveness.

Therapeutic Effects of microRNAs on Nonalcoholic Fatty Liver Disease (NAFLD) and Nonalcoholic Steatohepatitis (NASH): A Systematic Review and Meta-Analysis

Nonalcoholic fatty liver disease (NAFLD) has emerged as a global health problem that affects people even at young ages due to unhealthy lifestyles. Without intervention, NAFLD will develop into nonalcoholic steatohepatitis (NASH) and eventually liver cirrhosis and hepatocellular carcinoma. Although lifestyle interventions are therapeutic, effective implementation remains challenging. In the efforts to establish effective treatment for NAFLD/NASH, microRNA (miRNA)-based therapies began to evolve in the last decade. Therefore, this systematic review aims to summarize current knowledge on the promising miRNA-based approaches in NAFLD/NASH therapies. A current systematic evaluation and a meta-analysis were conducted according to the PRISMA statement. In addition, a comprehensive exploration of PubMed, Cochrane, and Scopus databases was conducted to perform article searches. A total of 56 different miRNAs were reported as potential therapeutic agents in these studies. miRNA-34a antagonist/inhibitor was found to be the most studied variant (n = 7), and it significantly improved the hepatic total cholesterol, total triglyceride, Aspartate Aminotransferase (AST), and Alanine Transaminase (ALT) levels based on a meta-analysis. The biological processes mediated by these miRNAs involved hepatic fat accumulation, inflammation, and fibrosis. miRNAs have shown enormous therapeutic potential in the management of NAFLD/NASH, wherein miRNA-34a antagonist has been found to be an exceptional potential agent for the treatment of NAFLD/NASH.

Immunotherapy-based novel nanoparticles in the treatment of gastrointestinal cancer: Trends and challenges

Gastrointestinal cancer (GIC) is the most common cancer with a poor prognosis. Currently, surgery is the main treatment for GIC. However, the high rate of postoperative recurrence leads to a low five-year survival rate. In recent years, immunotherapy has received much attention. As the only immunotherapy drugs approved by the Food and Drug Administration (FDA), immune checkpoint blockade (ICB) drugs have great potential in cancer therapy. Nevertheless, the efficacy of ICB treatment is greatly limited by the low immunogenicity and immunosuppressive microenvironment of GIC. Therefore, the targets of immunotherapy have expanded from ICB to increasing tumor immunogenicity, increasing the recruitment and maturation of immune cells and reducing the proportion of inhibitory immune cells, such as M2-like macrophages, regulatory T cells and myeloid-derived suppressor cells. Moreover, with the development of nanotechnology, a variety of nanoparticles have been approved by the FDA for clinical therapy, so novel nanodrug delivery systems have become a research focus for anticancer therapy. In this review, we summarize recent advances in the application of immunotherapy-based nanoparticles in GICs, such as gastric cancer, hepatocellular carcinoma, colorectal cancer and pancreatic cancer, and described the existing challenges and future trends.

MCCMF: collaborative matrix factorization based on matrix completion for predicting miRNA-disease associations

Background

MicroRNAs (miRNAs) are non-coding RNAs with regulatory functions. Many studies have shown that miRNAs are closely associated with human diseases. Among the methods to explore the relationship between the miRNA and the disease, traditional methods are time-consuming and the accuracy needs to be improved. In view of the shortcoming of previous models, a method, collaborative matrix factorization based on matrix completion (MCCMF) is proposed to predict the unknown miRNA-disease associations.

Results

The complete matrix of the miRNA and the disease is obtained by matrix completion. Moreover, Gaussian Interaction Profile kernel is added to the miRNA functional similarity matrix and the disease semantic similarity matrix. Then the Weight K Nearest Known Neighbors method is used to pretreat the association matrix, so the model is close to the reality. Finally, collaborative matrix factorization method is applied to obtain the prediction results. Therefore, the MCCMF obtains a satisfactory result in the fivefold cross-validation, with an AUC of 0.9569 (0.0005).

Conclusions

The AUC value of MCCMF is higher than other advanced methods in the fivefold cross validation experiment. In order to comprehensively evaluate the performance of MCCMF, accuracy, precision, recall and f-measure are also added. The final experimental results demonstrate that MCCMF outperforms other methods in predicting miRNA-disease associations. In the end, the effectiveness and practicability of MCCMF are further verified by researching three specific diseases.

Knockdown of MIR4435-2HG Suppresses the Proliferation, Migration and Invasion of Cervical Cancer Cells via Regulating the miR-128-3p/MSI2 Axis in vitro

PURPOSE

Long non-coding RNAs (lncRNAs) play major roles in the development of several cancers, including cervical cancer (CC). The purpose of the present study is to explore the regulatory mechanism of MIR4435-2HG on CC in vitro.

PATIENTS AND METHODS

Fifty-nine pairs of CC tissues and adjacent normal tissues were collected from 59 patients by resection. The expression of lncRNA MIR4435-2HG, microRNA (miR)-128-3p and Musashi 2 (MSI2) in CC tissues and cells was detected by quantitative reverse-transcription PCR (qRT-PCR). The viability of CC cells was detected by 3-(4, 5-Dimethyl-2-Thiazolyl)-2, 5-Diphenyl-2-H-Tetrazolium Bromide (MTT) assay. The ability of migration and invasion in CC cells was measured by wound healing assay and transwell invasion assay, respectively. Starbase software and Targetscan software were utilized to predict the relationship between miR-128 and MIR4435-2HG/MSI2, respectively. The dual-luciferase reporter assay was used to confirm these interactions.

RESULTS

LncRNA MIR4435-2HG expression was significantly up-regulated in CC tissues (P < 0.001) and cells (P < 0.01). Knockdown of MIR4435-2HG inhibited the proliferation, migration and invasion of CC cells (P < 0.01). MiR-128-3p was a target of MIR4435-2HG and was negatively modulated by MIR4435-2HG (P < 0.0001, r = -0.6331). Up-regulation of miR-128-3p suppressed the proliferation, migration and invasion of CC cells (P < 0.01). In addition, MSI2 was the target gene of miR-128-3p and negatively regulated by miR-128-3p (P < 0.0001, r = -0.4775). Both down-regulation of miR-128-3p and up-regulation of MSI2 reversed the inhibitory effects of MIR4435-2HG knockdown on the proliferation, migration and invasion of CC cells (P < 0.05).

CONCLUSION

MIR4435-2HG knockdown suppresses the proliferation, migration and invasion of CC cells through regulating the miR-128-3p/MSI2 axis, providing a possible therapeutic strategy for CC.

MicroRNAs Targeting MYC Expression: Trace of Hope for Pancreatic Cancer Therapy. A Systematic Review

Background

Pancreatic ductal adenocarcinoma (PDAC) is one of the deadliest malignancies and a major health problem worldwide. There were no major advances in conventional treatments in inhibiting tumor progression and increasing patient survival time. In order to suppress mechanisms responsible for tumor cell development such as those with oncogenic roles, more advanced therapeutic strategies should be sought. One of the most important oncogenes of pancreatic cancer is the MYC gene. The overexpression of MYC can activate many tumorigenic processes such as cell proliferation and pancreatic cancer cell invasion. MiRNAs are important molecules that are confirmed by targeting mRNA transcripts to regulate the expression of the MYC gene. Therefore, restoring MYC-repressing miRNAs expression tends to be an effective method of treating MYC-driven cancers.

Objective

The purpose of this study was to identify all validated microRNAs targeting C-MYC expression to inhibit PDAC progression by conducting a systematic review.

Methods

In this systematic review study, the papers published between 2000 and 2020 in major online scientific databases including PubMed, Scopus, and Web of Science were screened, following inclusion and exclusion criteria. We extracted all the experimental studies that showed miRNAs could target the expression of the MYC gene in PDAC.

Results

Eight papers were selected from a total of 89 papers. We found that six miRNAs (Let-7a, miR-145, miR-34a, miR-375, miR-494, and miR-148a) among the selected studies were validated for targeting MYC gene and three of them confirmed Let-7a as a direct MYC expression regulator in PC cells. Finally, we summarized the latest shreds of evidence of experimentally validated miRNAs targeting the MYC gene with respect to PDAC’s therapeutic potential.

Conclusion

Restoring the expression of MYC-repressing miRNAs tends to be an effective way to treat MYC-driven cancers such as PDAC. Several miRNAs have been proposed to target this oncogene via bioinformatics tools, but only a few have been experimentally validated for pancreatic cancer cells and models. Further studies should be conducted to find the interaction network of miRNA-MYC to develop more successful therapeutic strategies for PC, using the synergistic effects of these miRNAs.

Personalized RNA Medicine for Pancreatic Cancer

Purpose: Since drug responses vary between patients, it is crucial to develop pre-clinical or co-clinical strategies that forecast patient response. In this study, we tested whether RNA-based therapeutics were suitable for personalized medicine by using patient-derived-organoid (PDO) and patient-derived-xenograft (PDX) models.Experimental Design: We performed microRNA (miRNA) profiling of PDX samples to determine the status of miRNA deregulation in individual pancreatic ductal adenocarcinoma (PDAC) patients. To deliver personalized RNA-based-therapy targeting oncogenic miRNAs that form part of this common PDAC miRNA over-expression signature, we packaged antimiR oligonucleotides against one of these miRNAs in tumor-penetrating nanocomplexes (TPN) targeting cell surface proteins on PDAC tumors.Results: As a validation for our pre-clinical strategy, the therapeutic potential of one of our nano-drugs, TPN-21, was first shown to decrease tumor cell growth and survival in PDO avatars for individual patients, then in their PDX avatars.Conclusions: This general approach appears suitable for co-clinical validation of personalized RNA medicine and paves the way to prospectively identify patients with eligible miRNA profiles for personalized RNA-based therapy. Clin Cancer Res; 24(7); 1734-47. ©2018 AACR.

MicroRNA-192 regulates hypertrophic scar fibrosis by targeting SIP1

Hypertrophic scar (HS) is a fibro-proliferative disorder which is characterized by excessive deposition of collagen and accumulative activity of myofibroblasts. Increasing evidences have demonstrated miRNAs play a pivotal role in the pathogenesis of HS. MiR-192 is closely associated with renal fibrosis, but its effect on HS formation and skin fibrosis remains unknown. In the study, we presented that miR-192 was up-regulated in HS and HS derived fibroblasts (HSFs) compared to normal skin (NS) and NS derived fibroblasts (NSFs), accompanied by the reduction of smad interacting protein 1 (SIP1) expression and the increase of Col1, Col3 and α-SMA levels. Furthermore, we confirmed SIP1 was a direct target of miR-192 by using luciferase reporter assays. Meanwhile, the overexpression of miR-192 increased the levels of Col1, Col3 and α-SMA. The synthesis of collagen and more positive α-SMA staining were also observed in bleomycin-induced dermal fibrosis model of BALB/c mice treated with subcutaneous miR-192 mimics injection, whereas the inhibition of miR-192 decreased the expression of Col1, Col3 and α-SMA. Moreover, SIP1 siRNA could enhance the levels of Col1, Col3 and α-SMA, showing that the effect of knockdown SIP1 was similar to miR-192 mimics, and the phenomenon manifested miR-192 regulated HS fibrosis by targeting SIP1. Together, our results indicated that miR-192 was a critical factor of HS formation and facilitated skin fibrosis by targeting directly SIP1.

Screening candidate microRNAs (miRNAs) in different lambskin hair follicles in Hu sheep

Hu sheep lambskin is a unique white lambskin from China that exhibits three types of flower patterns, including small waves, medium waves, and large waves, with small waves considered the best quality. However, our understanding of the molecular mechanism underlying flower pattern formation in Hu sheep lambskin is limited. The aim of the present study was to further explore the relevance between candidate microRNAs (miRNAs) and developmental characteristics of hair follicles and screen miRNAs for later functional validation. Herein, we employed Illumina Hiseq 2500 to identify differentially expressed miRNAs in hair follicles of different flower patterns with small, medium, and large waves to construct a comprehensive sequence database on the mechanism of hair follicle development. Paraffin sections of lambskin tissue were prepared to assess the structure of different hair follicles. Expression levels of candidate miRNAs in different flower patterns were analyzed by relative quantitation using real-time PCR, combined with histological observation and micro-observation technologies, and the correlation between expression levels of candidate miRNAs and histological properties of hair follicles was analyzed by using SPSS 17.0. A total of 522 differentially expressed miRNAs were identified, and RNA-seq analysis detected 7,266 target genes in different groups of flower patterns. Gene ontological analysis indicated these target genes were mainly involved in cell proliferation, differentiation, growth, apoptosis, and ion transport, and 14 miRNAs, including miR-143, miR-10a, and let-7 were screened as candidate miRNAs in Hu sheep hair follicle growth and development. In the same field of vision, variance analysis showed that the number of secondary follicles in small waves was significantly larger than that in large and medium waves (P<0.01); the diameter of the primary and secondary follicles in large waves was respectively larger than those in medium and small waves (P<0.01). Combined with correlation analysis between miRNA expression and histological properties of hair follicles, highly significant differences in miRNA-143 expression levels between large and small waves were observed (P<0.01), and significant differences in the miRNA-10a expression levels between large and small waves (P<0.05) and in let-7i expression levels between large and medium waves were observed (P<0.05). Significant differences in the expression of novel miRNAs of NW_004080184.1_6326 between medium and large waves were detected (P<0.05), and highly significant differences between medium and small waves were observed (P<0.01). Highly significant differences in the expression level of NW_004080165.1_8572 between medium and large and small waves (P<0.01), in that of NW_004080181.1_3961 between medium and small waves (P<0.01), and in that of NW_004080190.1_13733 between medium and large waves were observed, whereas no significant differences in the other miRNAs among large, medium, and small waves were detected. Overall, the present study showed that miRNA-143, miRNA-10a, let-7i, NW_004080184.1_6326, NW_004080165.1_8572, NW_004080181.1_3961, and NW_004080190.1_13733 could be considered as important candidate genes, indicating these seven miRNAs may play significant roles in hair follicle growth and development in Hu sheep lambskin.

Circulating exosomes and exosomal microRNAs as biomarkers in gastrointestinal cancer

The most important biological function of exosomes is their possible use as biomarkers in clinical diagnosis. Compared with biomarkers identified in conventional specimens such as serum or urine, exosomal biomarkers provide the highest amount of sensitivity and specificity, which can be attributed to their excellent stability. Exosomes, which harbor different types of proteins, nucleic acids and lipids, are present in almost all bodily fluids. The molecular constituents of exosomes, especially exosomal proteins and microRNAs (miRNAs), are promising as biomarkers in clinical diagnosis. This discovery that exosomes also contain messenger RNAs and miRNAs shows that they could be carriers of genetic information. Although the majority of RNAs found in exosomes are degraded RNA fragments with a length of <200 nucleotides, some full-length RNAs might be present that may affect protein production in the recipient cell. In addition, exosomal miRNAs have been found to be associated with certain diseases. Several studies have pointed out miRNA contents of circulating exosomes that are similar to those of originating cancer cells. In this review, the recent advances in circulating exosomal miRNAs as biomarkers in gastrointestinal cancers are discussed. These studies indicated that miRNAs can be detected in exosomes isolated from body fluids such as saliva, which suggests potential advantages of using exosomal miRNAs as noninvasive novel biomarkers.

Senescence in Human Mesenchymal Stem Cells: Functional Changes and Implications in Stem Cell-Based Therapy

Regenerative medicine is extensively interested in developing cell therapies using mesenchymal stem cells (MSCs), with applications to several aging-associated diseases. For successful therapies, a substantial number of cells are needed, requiring extensive ex vivo cell expansion. However, MSC proliferation is limited and it is quite likely that long-term culture evokes continuous changes in MSCs. Therefore, a substantial proportion of cells may undergo senescence. In the present review, we will first present the phenotypic characterization of senescent human MSCs (hMSCs) and their possible consequent functional alterations. The accumulation of oxidative stress and dysregulation of key differentiation regulatory factors determine decreased differentiation potential of senescent hMSCs. Senescent hMSCs also show a marked impairment in their migratory and homing ability. Finally, many factors present in the secretome of senescent hMSCs are able to exacerbate the inflammatory response at a systemic level, decreasing the immune modulation activity of hMSCs and promoting either proliferation or migration of cancer cells. Considering the deleterious effects that these changes could evoke, it would appear of primary importance to monitor the occurrence of senescent phenotype in clinically expanded hMSCs and to evaluate possible ways to prevent in vitro MSC senescence. An updated critical presentation of the possible strategies for in vitro senescence monitoring and prevention constitutes the second part of this review. Understanding the mechanisms that drive toward hMSC growth arrest and evaluating how to counteract these for preserving a functional stem cell pool is of fundamental importance for the development of efficient cell-based therapeutic approaches.

A plausible role for actin gamma smooth muscle 2 (ACTG2) in small intestinal neuroendocrine tumorigenesis

BACKGROUND

Small intestinal neuroendocrine tumors (SI-NETs) originate from the enterochromaffin cells in the ileum and jejunum. The knowledge about genetic and epigenetic abnormalities is limited. Low mRNA expression levels of actin gamma smooth muscle 2 (ACTG2) have been demonstrated in metastases relative to primary SI-NETs. ACTG2 and microRNA-145 (miR-145) are aberrantly expressed in other cancers and ACTG2 can be induced by miR-145. The aim of this study was to investigate the role of ACTG2 in small intestinal neuroendocrine tumorigenesis.

METHODS

Protein expression was analyzed in SI-NETs (n = 24) and in enterochromaffin cells by immunohistochemistry. The cell line CNDT2.5 was treated with the histone methyltransferase inhibitor 3-deazaneplanocin A (DZNep), the selective EZH2 inhibitor EPZ-6438, or 5-aza-2'-deoxycytidine, a DNA hypomethylating agent. Cells were transfected with ACTG2 expression plasmid or miR-145. Western blotting analysis, quantitative RT-PCR, colony formation- and viability assays were performed. miR-145 expression levels were measured in tumors.

RESULTS

Eight primary tumors and two lymph node metastases displayed variable levels of positive staining. Fourteen SI-NETs and normal enterochromaffin cells stained negatively. Overexpression of ACTG2 significantly inhibited CNDT2.5 cell growth. Treatment with DZNep or transfection with miR-145 induced ACTG2 expression (>10-fold), but no effects were detected after treatment with EPZ-6438 or 5-aza-2'-deoxycytidine. DZNep also induced miR-145 expression. SI-NETs expressed relatively low levels of miR-145, with reduced expression in metastases compared to primary tumors.

CONCLUSIONS

ACTG2 is expressed in a fraction of SI-NETs, can inhibit cell growth in vitro, and is positively regulated by miR-145. Theoretical therapeutic strategies based on these results are discussed.

MicroRNA-192* impairs adipocyte triglyceride storage

We investigated the expression of miR-192* (miR-192-3p) in the visceral adipose tissue (VAT) of obese subjects and its function in cultured human adipocytes. This miRNA is a 3' arm derived from the same pre-miRNA as miR-192 (miR-192-5p) implicated in type 2 diabetes, liver disease and cancers, and is predicted to target key genes in lipid metabolism. In morbidly obese subjects undergoing bariatric surgery preceded by a very low calorie diet, miR-192* in VAT correlated negatively (r=-0.387; p=0.046) with serum triglyceride (TG) and positively with high-density lipoprotein (HDL) concentration (r=0.396; p=0.041). In a less obese patient cohort, the miRNA correlated negatively with the body mass index (r=-0.537; p=0.026). To characterize the function of miR-192*, we overexpressed it in cultured adipocytes and analyzed the expression of adipogenic differentiation markers as well as cellular TG content. Reduced TG and expression of the adipocyte marker proteins aP2 (adipocyte protein 2) and perilipin 1 were observed. The function of miR-192* was further investigated by transcriptomic profiling of adipocytes expressing this miRNA, revealing impacts on key lipogenic genes. A number of the mRNA alterations were validated by qPCR. Western analysis confirmed a marked reduction of the lipogenic enzyme SCD (stearoyl coenzyme A desaturase-1), the fatty aldehyde dehydrogenase ALDH3A2 (aldehyde dehydrogenase 3 family member A2) and the high-density lipoprotein receptor SCARB1 (scavenger receptor B, type I). SCD and ALDH3A2 were demonstrated to be direct targets of miR-192*. To conclude, the present data identify miR-192* as a novel controller of adipocyte differentiation and lipid homeostasis.

Atypical role of sprouty in colorectal cancer: sprouty repression inhibits epithelial-mesenchymal transition

Sprouty (SPRY) appears to act as a tumor suppressor in cancer, whereas we demonstrated that SPRY2 functions as a putative oncogene in colorectal cancer (CRC) (Oncogene, 2010, 29: 5241-5253). We investigated the mechanisms by which SPRY regulates epithelial-mesenchymal transition (EMT) in CRC. SPRY1 and SPRY2 mRNA transcripts were significantly upregulated in human CRC. Suppression of SPRY2 repressed AKT2 and EMT-inducing transcription factors and significantly increased E-cadherin expression. Concurrent downregulation of SPRY1 and SPRY2 also increased E-cadherin and suppressed mesenchymal markers in colon cancer cells. An inverse expression pattern between AKT2 and E-cadherin was established in a human CRC tissue microarray. SPRY2 negatively regulated miR-194-5p that interacts with AKT2 3' untranslated region. Mir-194 mimics increased E-cadherin expression and suppressed cancer cell migration and invasion. By confocal microscopy, we demonstrated redistribution of E-cadherin to plasma membrane in colon cancer cells transfected with miR-194. Spry1(-/-) and Spry2(-/-) double mutant mouse embryonic fibroblasts exhibited decreased cell migration while acquiring several epithelial markers. In CRC, SPRY drive EMT and may serve as a biomarker of poor prognosis.

MYC in pancreatic cancer: novel mechanistic insights and their translation into therapeutic strategies

Owing to its aggressiveness, late detection and marginal therapeutic accessibility, pancreatic ductal adenocarcinoma (PDAC) remains a most challenging malignant disease. Despite scientific progress in the understanding of the mechanisms that underly PDAC initiation and progression, the successful translation of experimental findings into effective new therapeutic strategies remains a largely unmet need. The oncogene MYC is activated in many PDAC cases and is a master regulator of vital cellular processes. Excellent recent studies have shed new light on the tremendous functions of MYC in cancer and identified inhibition of MYC as a likewise beneficial and demanding effort. This review will focus on mechanisms that contribute to deregulation of MYC expression in pancreatic carcinogenesis and progression and will summarize novel biological findings from recent in vivo models. Finally, we provide a perspective, how regulation of MYC in PDAC may contribute to the development of new therapeutic approaches.

Cell senescence abrogates the therapeutic potential of human mesenchymal stem cells in the lethal endotoxemia model

Mesenchymal stem cells (MSCs) possess unique paracrine and immunosuppressive properties, which make them useful candidates for cellular therapy. Here, we address how cellular senescence influences the therapeutic potential of human MSCs (hMSCs). Senescence was induced in bone marrow-derived hMSC cultures with gamma irradiation. Control and senescent cells were tested for their immunoregulatory activity in vitro and in vivo, and an extensive molecular characterization of the phenotypic changes induced by senescence was performed. We also compared the gene expression profiles of senescent hMSCs with a collection of hMSCs used in an ongoing clinical study of Graft Versus Host disease (GVHD). Our results show that senescence induces extensive phenotypic changes in hMSCs and abrogates their protective activity in a murine model of LPS-induced lethal endotoxemia. Although senescent hMSCs retain an ability to regulate the inflammatory response on macrophages in vitro, and, in part retain their capacity to significantly inhibit lymphocyte proliferation, they have a severely impaired migratory capacity in response to proinflammatory signals, which is associated with an inhibition of the AP-1 pathway. Additionally, expression analysis identified PLEC, C8orf48, TRPC4, and ZNF14, as differentially regulated genes in senescent hMSCs that were similarly regulated in those hMSCs which failed to produce a therapeutic effect in a GVHD trial. All the observed phenotypic alterations were confirmed in replicative-senescent hMSCs. In conclusion, this study highlights important changes in the immunomodulatory phenotype of senescent hMSCs and provides candidate gene signatures which may be useful to evaluate the therapeutic potential of hMSCs used in future clinical studies.

Establishing reliable miRNA-cancer association network based on text-mining method

Associating microRNAs (miRNAs) with cancers is an important step of understanding the mechanisms of cancer pathogenesis and finding novel biomarkers for cancer therapies. In this study, we constructed a miRNA-cancer association network (miCancerna) based on more than 1,000 miRNA-cancer associations detected from millions of abstracts with the text-mining method, including 226 miRNA families and 20 common cancers. We further prioritized cancer-related miRNAs at the network level with the random-walk algorithm, achieving a relatively higher performance than previous miRNA disease networks. Finally, we examined the top 5 candidate miRNAs for each kind of cancer and found that 71% of them are confirmed experimentally. miCancerna would be an alternative resource for the cancer-related miRNA identification.

High-throughput sequencing reveals differential expression of miRNAs in intestine from sea cucumber during aestivation

The regulatory role of miRNA in gene expression is an emerging hot new topic in the control of hypometabolism. Sea cucumber aestivation is a complicated physiological process that includes obvious hypometabolism as evidenced by a decrease in the rates of oxygen consumption and ammonia nitrogen excretion, as well as a serious degeneration of the intestine into a very tiny filament. To determine whether miRNAs play regulatory roles in this process, the present study analyzed profiles of miRNA expression in the intestine of the sea cucumber (Apostichopus japonicus), using Solexa deep sequencing technology. We identified 308 sea cucumber miRNAs, including 18 novel miRNAs specific to sea cucumber. Animals sampled during deep aestivation (DA) after at least 15 days of continuous torpor, were compared with animals from a non-aestivation (NA) state (animals that had passed through aestivation and returned to the active state). We identified 42 differentially expressed miRNAs [RPM (reads per million) >10, |FC| (|fold change|) ≥ 1, FDR (false discovery rate) <0.01] during aestivation, which were validated by two other miRNA profiling methods: miRNA microarray and real-time PCR. Among the most prominent miRNA species, miR-200-3p, miR-2004, miR-2010, miR-22, miR-252a, miR-252a-3p and miR-92 were significantly over-expressed during deep aestivation compared with non-aestivation animals. Preliminary analyses of their putative target genes and GO analysis suggest that these miRNAs could play important roles in global transcriptional depression and cell differentiation during aestivation. High-throughput sequencing data and microarray data have been submitted to GEO database.

MicroRNA-21: a therapeutic target for reversing drug resistance in cancer

INTRODUCTION

Drug resistance is a major clinical obstacle to the successful treatment of human cancer. The microRNAs-21 (miR-21), an oncomiR, may play an important role in the progress of drug resistance.

AREAS COVERED

This review covers all related literature on miR-21 in drug resistance of human cancers and analyzes the expression, biological functions and targets of it. This study also envisages future developments toward its clinical and therapeutic applications in cancer treatment.

EXPERT OPINION

The miR-21 may promote the drug resistance of various cancers. Inhibitors of miR-21 may function as effective approaches for reversing drug resistance in cancer cells. There is a tough way from discovering the function of miR-21 to clinical use. Further understanding of miR-21-mediated signaling pathways will help to promote the therapeutic-clinical use of miR-21 in cancer.

MicroRNAs Involved in Anti-Tumour Immunity

MicroRNAs (miRNAs) are a category of small RNAs that constitute a new layer of complexity to gene regulation within the cell, which has provided new perspectives in understanding cancer biology. The deregulation of miRNAs contributes critically to the development and pathophysiology of a number of cancers. miRNAs have been found to participate in cell transformation and multiplication by acting as tumour oncogenes or suppressors; therefore, harnessing miRNAs may provide promising cancer therapeutics. Another major function of miRNAs is their activity as critical regulatory vehicles eliciting important regulatory processes in anti-tumour immunity through their influence on the development, differentiation and activation of various immune cells of both innate and adaptive immunity. This review aims to summarise recent findings focusing on the regulatory mechanisms of the development, differentiation, and proliferative aspects of the major immune populations by a diverse profile of miRNAs and may enrich our current understanding of the involvement of miRNAs in anti-tumour immunity.

MicroRNA-224 negatively regulates p21 expression during late neoplastic progression in inflammatory bowel disease

BACKGROUND

The development of colon cancer represents a major complication in patients with inflammatory bowel disease (IBD). The importance of microRNAs (miRs) in carcinogenesis is becoming clearer because miRs have been implicated in the regulation of cancer-related cellular processes to include apoptosis, differentiation, cell cycle progression, and immune function. In the current study, we sought to identify miR dysregulation specific to progression along the normal-inflammation-cancer axis in colonic specimens from patients with IBD.

METHODS

MiR microarrays and quantitative reverse transcription PCR were used to detect and confirm dysregulated miRs. Receiver operating characteristic curve analysis was applied to evaluate the potential use of miR-224 as a neoplastic disease marker in IBD. For miR-224 target messenger RNA (mRNA) identification, mRNA microarrays were employed in combination with bioinformatic analyses, Western blotting, and luciferase activity measurements.

RESULTS

We identified 30 miRs that were differentially expressed between chronically inflamed mucosae and cancers arising from IBD tissues. MiR-224 levels increased successively at each stage of IBD progression and accurately discriminated cancers from normal or chronically inflamed IBD tissues. Moreover, mRNA arrays combined with bioinformatic analyses suggested the participation of miR-224 in cell cycle regulation. Subsequently, cell cycle experiments indicated that miR-224 regulates the G1-S checkpoint. Finally, in silico prediction analyses, confirmed by Western blotting and luciferase assays, identified p21 as a specific direct mRNA target of miR-224.

CONCLUSIONS

These findings reveal miR dysregulation specific to IBD-associated colorectal carcinoma. MiR-224 is overexpressed in IBD cancers and targets p21, a key cell cycle regulator. Moreover, these results establish the participation of miR-224 in IBD carcinogenesis.

Cancer-associated-fibroblasts and tumour cells: a diabolic liaison driving cancer progression

Several recent papers have now provided compelling experimental evidence that the progression of tumours towards a malignant phenotype does not depend exclusively on the cell-autonomous properties of cancer cells themselves but is also deeply influenced by tumour stroma reactivity, thereby undergoing a strict environmental control. Tumour microenvironmental elements include structural components such as the extracellular matrix or hypoxia as well as stromal cells, either resident cells or recruited from circulating precursors, as macrophages and other inflammatory cells, endothelial cells and cancer-associated fibroblasts (CAFs). All these elements synergistically play a specific role in cancer progression. This review summarizes our current knowledge on the role of CAFs in tumour progression, with a particular focus on the biunivocal interplay between CAFs and cancer cells leading to the activation of the epithelial-mesenchymal transition programme and the achievement of stem cell traits, as well as to the metabolic reprogramming of both stromal and cancer cells. Recent advances on the role of CAFs in the preparation of metastatic niche, as well as the controversial origin of CAFs, are discussed in light of the new emerging therapeutic implications of targeting CAFs.

Differential expression of miRNAs in colorectal cancer: comparison of paired tumor tissue and adjacent normal mucosa using high-throughput sequencing

We present the results of a global study of dysregulated miRNAs in paired samples of normal mucosa and tumor from eight patients with colorectal cancer. Although there is existing data of miRNA contribution to colorectal tumorigenesis, these studies are typically small to medium scale studies of cell lines or non-paired tumor samples. The present study is to our knowledge unique in two respects. Firstly, the normal and adjacent tumor tissue samples are paired, thus taking into account the baseline differences between individuals when testing for differential expression. Secondly, we use high-throughput sequencing, thus enabling a comprehensive survey of all miRNAs expressed in the tissues. We use Illumina sequencing technology to perform sequencing and two different tools to statistically test for differences in read counts per gene between samples: edgeR when using the pair information and DESeq when ignoring this information, i.e., treating tumor and normal samples as independent groups. We identify 37 miRNAs that are significantly dysregulated in both statistical approaches, 19 down-regulated and 18 up-regulated. Some of these miRNAs are previously published as potential regulators in colorectal adenocarcinomas such as miR-1, miR-96 and miR-145. Our comprehensive survey of differentially expressed miRNAs thus confirms some existing findings. We have also discovered 16 dysregulated miRNAs, which to our knowledge have not previously been associated with colorectal carcinogenesis: the following significantly down-regulated miR-490-3p, -628-3p/-5p, -1297, -3151, -3163, -3622a-5p, -3656 and the up-regulated miR-105, -549, -1269, -1827, -3144-3p, -3177, -3180-3p, -4326. Although the study is preliminary with only eight patients included, we believe the results add to the present knowledge on miRNA dysregulation in colorectal carcinogenesis. As such the results would serve as a robust training set for validation of potential biomarkers in a larger cohort study. Finally, we also present data supporting the hypothesis that there are differences in miRNA expression between adenocarcinomas and neuroendocrine tumors of the colon.

A novel miR-155/miR-143 cascade controls glycolysis by regulating hexokinase 2 in breast cancer cells

Cancer cells preferentially metabolize glucose through aerobic glycolysis. This phenomenon, known as the Warburg effect, is an anomalous characteristic of glucose metabolism in cancer cells. Chronic inflammation is a key promoting factor of tumourigenesis. It remains, however, largely unexplored whether and how pro-tumourigenic inflammation regulates glucose metabolism in cancer cells. Here, we show that pro-inflammatory cytokines promote glycolysis in breast cancer cells, and that the inflammation-induced miR-155 functions as an important mediator in this process. We further show that miR-155 acts to upregulate hexokinase 2 (hk2), through two distinct mechanisms. First, miR-155 promotes hk2 transcription by activation of signal transducer and activator of transcription 3 (STAT3), a transcriptional activator for hk2. Second, via targeting C/EBPβ (a transcriptional activator for mir-143), miR-155 represses mir-143, a negative regulator of hk2, thus resulting in upregulation of hk2 expression at the post-transcriptional level. The miR-155-mediated hk2 upregulation also appears to operate in other types of cancer cells examined. We suggest that the miR-155/miR-143/HK2 axis may represent a common mechanism linking inflammation to the altered metabolism in cancer cells.