MicroRNA biogenesis and cancer

Dual role of miR-155 and exosomal miR-155 in tumor angiogenesis: implications for cancer progression and therapy

Tumor angiogenesis facilitates cancer progression by supporting tumor growth and metastasis. MicroRNA-155 (miR-155) plays a pivotal role in regulating angiogenesis through both direct effects on tumor and endothelial cells and indirect modulation via exosomal communication. This review highlights miR-155's pro-angiogenic influence on endothelial cell behavior and tumor microenvironment remodeling. Additionally, exosomal miR-155 enhances intercellular communication, promoting vascularization in several cancers. Emerging therapeutic strategies include miR-155 inhibition using antagomirs, exosome-mediated delivery systems, and modulation of pathways such as JAK2/STAT3 and TGF-β/SMAD2. Targeting miR-155 represents a promising approach to hinder tumor angiogenesis and improve cancer therapy outcomes.

Aloin and CPT-11 combination activates miRNA-133b and downregulates IGF1R- PI3K/AKT/mTOR and MEK/ERK pathways to inhibit colorectal cancer progression

CPT-11 is one of the drugs employed in colorectal cancer treatment and has faced challenges in the form of resistance. The insulin-like growth factor 1 receptor is a tyrosine kinase receptor that mediates cancer cell survival and drug resistance. It is frequently overexpressed in colorectal cancer and has previously been identified as a microRNA target. MicroRNAs are non-coding RNA molecules that regulate gene function by suppressing messenger RNA translation. Studies have demonstrated that natural compounds can regulate microRNA function and their target genes. Therefore, combining natural compounds with existing cancer drugs can enhance the therapeutic efficacy. We investigated a natural compound, Aloin, for the potential sensitization of colorectal cancer to CPT-11. We used western blot, MTT cell viability assay, flow cytometry, and microRNA/gene knockdown and overexpression experiments, as well as an in vivo mouse model. Our investigation revealed that combining Aloin with CPT-11 exerts an enhanced anti-tumor effect in colorectal cancer. This combination reduced cell viability and induced apoptosis, both in vivo and in vitro. Furthermore, this combination upregulated miRNA-133b, while downregulating the IGF1R and its downstream MEK/ERK, and PI3K/AKT/mTOR pathways. Our findings suggests that CPT-11 and Aloin are potential combination treatment partners against colorectal cancer. MicroRNA-133b may serve as a co-therapeutic target with IGF1R against colorectal cancer, which might overcome the existing treatment limitations.

Association of DROSHA rs6877842, rs642321 and rs10719 polymorphisms with increased susceptibility to breast cancer: A case-control study with genotype and haplotype analysis

BACKGROUND

Multiple lines of evidence suggest that single nucleotide polymorphisms (SNPs) in genes encoding components of the microRNA processing machinery may underlie susceptibility to various human diseases, including cancer.

OBJECTIVE

The present study aimed to investigate whether rs6877842, rs642321 and rs10719 SNPs of DROSHA, a key component of the miRNA biogenesis pathway, are associated with increased risk of breast cancer.

METHODS

A total of 100 patients diagnosed with breast cancer and 100 healthy women were included. Following extraction of DNA, genotyping was performed by tetra primer- amplification refractory mutation system-PCR (T-ARMS-PCR) technique. Under the co-dominant, dominant and recessive inheritance models, the association between DROSHA SNPs and breast cancer risk was determined by logistic regression analysis. The association of DROSHA SNPs with patients' clinicopathological parameters was assessed. Also, haplotype analysis was performed to evaluate the combined effect of DROSHA SNPs on breast cancer risk.

RESULTS

We observed a statistically significant association between DROSHA rs642321 polymorphism and breast cancer susceptibility (P < 0.05). Under the dominant inheritance model, DROSHA rs642321 polymorphism was significantly associated with increased risk of breast cancer (OR: 6.091; 95% CI: 3.291-11.26; P = 0.0001). Our findings demonstrated that DROSHA rs642321 T allele can contribute to the development of breast cancer (OR: 3.125; 95% CI: 1.984-4.923; P = 0.0001). We also found that GTC and GTT haplotypes conferred significant risk for breast cancer (OR: 2.367; 95% CI: 1.453-3.856; P = 0.0001 and OR: 7.944; 95% CI: 2.073-30.43; P = 0.0001, respectively).

CONCLUSIONS

These results provide the first evidence that DROSHA rs642321 polymorphism is associated with increased risk of breast cancer. However, further studies are needed to firmly validate these findings.

Role of mechano-sensitive non-coding RNAs in bone remodeling of orthodontic tooth movement: recent advances

Orthodontic tooth movement relies on bone remodeling and periodontal tissue regeneration in response to the complicated mechanical cues on the compressive and tensive side. In general, mechanical stimulus regulates the expression of mechano-sensitive coding and non-coding genes, which in turn affects how cells are involved in bone remodeling. Growing numbers of non-coding RNAs, particularly mechano-sensitive non-coding RNA, have been verified to be essential for the regulation of osteogenesis and osteoclastogenesis and have revealed how they interact with signaling molecules to do so. This review summarizes recent findings of non-coding RNAs, including microRNAs and long non-coding RNAs, as crucial regulators of gene expression responding to mechanical stimulation, and outlines their roles in bone deposition and resorption. We focused on multiple mechano-sensitive miRNAs such as miR-21, - 29, -34, -103, -494-3p, -1246, -138-5p, -503-5p, and -3198 that play a critical role in osteogenesis function and bone resorption. The emerging roles of force-dependent regulation of lncRNAs in bone remodeling are also discussed extensively. We summarized mechano-sensitive lncRNA XIST, H19, and MALAT1 along with other lncRNAs involved in osteogenesis and osteoclastogenesis. Ultimately, we look forward to the prospects of the novel application of non-coding RNAs as potential therapeutics for tooth movement and periodontal tissue regeneration.

The effect of mesenchymal stromal cells ın the microenvironment on cancer development

Inflammatory signals secreted from the tumor microenvironment are thought to promote tumor growth and survival. It has been reported that stromal cells in the tumor microenvironment have similar characteristics to tumor-associated cells. In addition miRNAs play critical roles in various diseases, including cancer. In this study, we aimed to investigate the effects of co-culture of cancer cells and stromal cells isolated from normal and malignant breast tissue on each other and the possible effects of miRNAs on these interactions. The characterized stromal cells were co-cultured with an MDA-MB-231 cancer cell line. The proliferation capacity of the experimental groups was evaluated using the WST-1 assay. The expression of breast cancer-specific miRNAs and related genes were assessed by real-time PCR. ELISA assay was performed to determine the concentration of some cytokines and chemokines. We found that the microenvironment plays an important role in the development of cancer, confirming the changes in the expression of oncogenic and tumor suppressor miRNA and their target genes after co-culture with malignant stromal cells. As a result of the studies, specific gene expressions of related signaling pathways were detected in correlation with miRNA changes and the effects of tumor microenvironment on tumorigenesis were revealed in detail. miRNAs have been shown to play an important role in cancer development in recent studies. The idea that these small molecules can be used in diagnosis and treatment is becoming stronger day by day. We believe that new treatment approaches involving the tumor microenvironment and using miRNAs as markers are promising.

Impacts of MicroRNAs Induced by the Gut Microbiome on Regulating the Development of Colorectal Cancer

Although a dysfunctional gut microbiome is strongly linked to colorectal cancer (CRC), our knowledge of the mediators between CRC and the microbiome is limited. MicroRNAs (miRNAs) affect critical cellular processes, such as apoptosis, proliferation, and differentiation, and contribute to the regulation of CRC progression. Increasingly, studies found that miRNAs can significantly mediate bidirectional interactions between the host and the microbiome. Notably, miRNA expression is regulated by the gut microbiome, which subsequently affects the host transcriptome, thereby influencing the development of CRC. This study typically focuses on the specific functions of the microbiome in CRC and their effect on CRC-related miRNA production and reviews the role of several bacteria on miRNA, including Fusobacterium nucleatum, Escherichia coli, enterotoxigenic Bacteroides fragilis, and Faecalibacterium prausnitzii. Based on the important roles of miRNAs and the gut microbiome in CRC, strategies for modulating miRNA expression and regulating the gut microbiome composition need to be applied, such as bioactive dietary components and fecal microorganism transplantation.

LncSNHG1 Promoted CRC Proliferation through the miR-181b-5p/SMAD2 Axis

Objective

To investigate the effects of LncRNA SNHG1 on the proliferation, migration, and epithelial-mesenchymal transition (EMT) of colorectal cancer cells (CRCs).

Methods

4 pairs of CRC tissue samples and their corresponding adjacent samples were analyzed by the human LncRNA microarray chip. The expression of LncSNHG1 in CRC cell lines was verified by qRT-PCR. Colony formation assays and CCK8 assays were applied to study the changes in cell proliferation. The transwell assay and wound healing experiments were used to verify the cell invasion and migration. EMT progression was confirmed finally.

Results

LncSNHG1 was overexpressed both in CRC tissues and cell lines, while the miR-181b-5p expression was decreased in CRC cell lines. After knock-down of LncSNHG1, the proliferation, invasion, and migration of HT29 and SW620 cells were all decreased. Meanwhile, LncSNHG1 enhanced EMT progress through regulation of the miR-181b-5p/SMAD2 axis.

Conclusion

LncSNHG1 promotes colorectal cancer cell proliferation and invasion through the miR-181b-5p/SMAD2 axis.

17β-Estradiol Regulates miR-9-5p and miR-9-3p Stability and Function in the Aged Female Rat Brain

Clinical studies demonstrated that the ovarian hormone 17β-estradiol (E2) is neuroprotective within a narrow window of time following menopause, suggesting that there is a biological switch in E2 action that is temporally dependent. However, the molecular mechanisms mediating this temporal switch have not been determined. Our previous studies focused on microRNAs (miRNA) as one potential molecular mediator and showed that E2 differentially regulated a subset of mature miRNAs which was dependent on age and the length of time following E2 deprivation. Notably, E2 significantly increased both strands of the miR-9 duplex (miR-9-5p and miR-9-3p) in the hypothalamus, raising the possibility that E2 could regulate miRNA stability/degradation. We tested this hypothesis using a biochemical approach to measure miRNA decay in a hypothalamic neuronal cell line and in hypothalamic brain tissue from a rat model of surgical menopause. Notably, we found that E2 treatment stabilized both miRNAs in neuronal cells and in the rat hypothalamus. We also used polysome profiling as a proxy for miR-9-5p and miR-9-3p function and found that E2 was able to shift polysome loading of the miRNAs, which repressed the translation of a predicted miR-9-3p target. Moreover, miR-9-5p and miR-9-3p transcripts appeared to occupy different fractions of the polysome profile, indicating differential subcellular. localization. Together, these studies reveal a novel role for E2 in modulating mature miRNA behavior, independent of its effects at regulating the primary and/or precursor form of miRNAs.

MiR-335-3p inhibits cell proliferation, induces cell cycle arrest and apoptosis in acute myeloid leukemia by targeting EIF3E

Here, we aimed to investigate the biological roles and the regulatory mechanisms of miR-335-3p in acute myeloid leukemia (AML). We first found miR-335-3p was significantly down-regulated in blood samples from leukemia patients and cell lines using reverse transcription quantitative PCR. Through CCK-8 assay and flow cytometry, we observed that miR-335-3p overexpression significantly inhibited cell proliferation, induced cell cycle G0/G1 arrest and apoptosis in AML cell lines (THP-1 and U937). Moreover, miR-335-3p directly targets EIF3E and negatively regulated its expression. More importantly, EIF3E overexpression reversed the effects of miR-335-3p on cell proliferation, G1/S transition and apoptosis. Furthermore, miR-335-3p overexpression obviously downregulated the expression of CDK4, Cyclin D1 and Bcl-2, while upregulated the expression of p21 and Bad, which were significantly rescued by the co-transfection of pcDNA3.1-EIF3E. Collectively, our study proposes that miR-335-3p/EIF3E axis could be a promising therapeutic target to mitigate the progression of AML.

Downregulation of circ_0012152 inhibits proliferation and induces apoptosis in acute myeloid leukemia cells through the miR-625-5p/SOX12 axis

Acute myeloid leukemia (AML) is a highly heterogeneous disease featured by a clonal proliferation derived from primitive hematopoietic stem/progenitor cells. Circular RNAs (circRNAs) have been identified as crucial regulators in the progression of various cancers, including AML. However, the molecular mechanism of AML is still not definite. This study aimed to explore the influences of circ_0012152 on cell development in AML cells and the underlying regulatory mechanism. The expression of circ_0012152, microRNA-625-5p (miR-625-5p) and sex-determining region Y-related high mobility group box 12 (SOX12) was detected by quantitative real-time polymerase chain reaction. The proliferation of AML cells was evaluated by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assay for cell viability, 5-ethynyl-2'-deoxyuridine incorporation assay for DNA biosynthesis and flow cytometry for cell cycle distribution, respectively. The death of AML cells was detected by flow cytometry. The protein expression was assessed by Western blot assay. Dual-luciferase reporter and RNA immunoprecipitation assays were carried out to examine the relationships among circ_0012152, miR-625-5p and SOX12. The expression of circ_0012152 was increased in AML tissues and cells and circ_0012152 knockdown suppressed proliferation and promoted death in AML cells. Further exploration revealed that circ_0012152 inhibited miR-625-5p expression and downregulation of miR-625-5p overturned the effects of circ_0012152 knockdown on proliferation and death in AML cells. Moreover, miR-625-5p targeted SOX12 and circ_0012152 facilitated the expression of SOX12 by relieving miR-625-5p-mediated inhibitory effect on SOX12 in AML cells. Circ_0012152 knockdown suppressed cell proliferation and promoted death by targeting SOX12 mediated by miR-625-5p in AML cells.

Silencing of circular RNA_0000326 inhibits cervical cancer cell proliferation, migration and invasion by boosting microRNA-338-3p-dependent down-regulation of CDK4

Cervical cancer is one of the leading causes of cancer-related death among women, which is attributed partly by limited treatment options. Recent studies have provided in-depth explanations regarding the role of circular RNA in cancers. We aimed to investigate the role of circular RNA_0000326 in cervical cancer. Bioinformatics analysis revealed a high circ_0000326 expression in cervical cancer. Cervical cancer cells and tissues were also observed to have elevated levels of circ_0000326 and the upregulation of circ_0000326 depended on the stage of cancer. Transfection with siRNA of circ_0000326 resulted in the inhibition of proliferation, migration and cell cycle of cancer cells. Interestingly, we confirmed that circ_0000326 served as a sponge for microRNA-338-3p and that the miRNA bound to Cyclin-dependent kinase 4. In the presence of microRNA-338-3p mimic or silencing of circ_0000326, Cyclin-dependent kinase 4 expression was decreased. Transfection with microRNA-338-3p mimic inhibited cell clone formation and proliferation. Moreover, in vivo experiment revealed that the injection of shRNA-circ_0000326 lentivirus suppressed tumor growth and decreased Cyclin-dependent kinase 4 expression. Taken altogether, our results showed that circ_0000326 exerted oncogenic effects on cervical cancer by upregulating Cyclin-dependent kinase 4 via sponging microRNA-338-3p. This systematic investigation on circ_0000326 could provide further insight into cervical cancer.

Long non-coding RNA CERS6-AS1 facilitates the oncogenicity of pancreatic ductal adenocarcinoma by regulating the microRNA-15a-5p/FGFR1 axis

The long non-coding RNA CERS6 antisense RNA 1 (CERS6-AS1) has critical regulatory roles in breast cancer progression. Here, we determined CERS6-AS1 expression in pancreatic ductal adenocarcinoma (PDAC) and the roles of CERS6-AS1 in PDAC carcinogenesis. The mechanisms underlying the regulatory actions of CERS6-AS1 in PDAC cells were elucidated in detail. CERS6-AS1 expression was evidently increased in PDAC tissues and cell lines. Patients with PDAC having high CERS6-AS1 expression had shorter overall survival periods than those having low CERS6-AS1 expression. Functionally, the knockdown of CERS6-AS1 attenuated the proliferation, migration, and invasion and stimulated apoptosis of PDAC cells in vitro. Additionally, CERS6-AS1 depletion decreased PDAC tumor growth in vivo. Mechanistically, CERS6-AS1 could competitively bind to microRNA-15a-5p (miR-15a-5p) and effectively work as a molecular sponge in PDAC cells, resulting in the upregulation of fibroblast growth factor receptor 1 (FGFR1), a direct target of miR-15a-5p. Rescue experiments revealed that miR-15a-5p downregulation or FGFR1 restoration rescued the effects of CERS6-AS1 knockdown on the behaviors of PDAC cells. In conclusion, CERS6-AS1 promoted the oncogenicity of PDAC by serving as a competing endogenous RNA to sequester miR-15a-5p and increase FGFR1 expression, which highlights the potential of the CERS6-AS1/miR-15a-5p/FGFR1 pathway as an effective target for cancer therapy.

The Role and Expression of Angiogenesis-Related miRNAs in Gastric Cancer

Gastric cancer (GC) is the fifth most frequently diagnosed malignant tumor and the third highest cause of cancer mortality worldwide. For advanced GC, many novel drugs and combinations have been tested, but results are still disappointing, and the disease is incurable in the majority of cases. In this regard, it is critical to investigate the molecular mechanisms underlying GC development. Angiogenesis is one of the hallmarks of cancer with a fundamental role in GC growth and progression. Ramucirumab, a monoclonal antibody that binds to vascular endothelial growth factor-2 (VEGFR-2), is approved in the treatment of advanced and pretreated GC. However, no predictive biomarkers for ramucirumab have been identified so far. Micro RNAs (miRNAs) are a class of evolutionarily-conserved single-stranded non-coding RNAs that play an important role (via post-transcriptional regulation) in essentially all biologic processes, such as cell proliferation, differentiation, apoptosis, survival, invasion, and migration. In our review, we aimed to analyze the available data on the role of angiogenesis-related miRNAs in GC.

Pathogenetic Role and Clinical Implications of Regulatory RNAs in Biliary Tract Cancer

Biliary tract cancer (BTC) is characterised by poor prognosis and low overall survival in patients. This is generally due to minimal understanding of its pathogenesis, late diagnosis and limited therapeutics in preventing or treating BTC patients. Non-coding RNA (ncRNA) are small RNAs (mRNA) that are not translated to proteins. ncRNAs were considered to be of no importance in the genome, but recent studies have shown they play essential roles in biology and oncology such as transcriptional repression and degradation, thus regulating mRNA transcriptomes. This has led to investigations into the role of ncRNAs in the pathogenesis of BTC, and their clinical implications. In this review, the mechanisms of action of ncRNA are discussed and the role of microRNAs in BTC is summarised. The scope of this review will be limited to miRNA as they have been shown to play the most significant roles in BTC progression. There is huge potential in miRNA-based biomarkers and therapeutics in BTC, but more studies, research and technological advancements are required before it can be translated into clinical practice for patients.

Anti-Micro RNA-221 a Promising Genetic Therapy of Oral Squamous Cell Carcinoma (SCC-25)

Micro-RNA-221(miR-221) is one of oncogenic miRNAs that plays a vital role in the development and progression of oral cancers. The aim of this study is to introduce a new gene therapy for oral squamous cell carcinoma by blocking the expression of oncogenic miR-221 by its inhibitor. The present work was performed on squamous cell carcinoma cell line SCC-25 and anti-miR-221 was delivered to the cells using an ultrasound micro bubbles. Assessment of the effect of miR-221 inhibitor on SCC-25 cells was done using MTT assay, cell cycle analysis and apoptosis detection. In addition, reverse transcription-polymerase chain reaction was also used to detect the expression -miR-221 and its target genes. Using ANOVA, statistical analysis of the results showed significant inhibition of cell viability with and induction of cell apoptosis of SCC-25 cell line after transfection. Moreover, the expression of miR-221, Epidermal growth factor receptor (EGFR) and CDKNIB/p27 were downregulated without significant difference. Transfection of SCC-25 by inhibitor of miR-221 resulting in blockage of its expression leading to arresting of tumor growth. These results proved the effective role of micro-RNA inhibitors as novel therapeutic agent for oral cancers.

MicroRNA miR-155-5p knockdown attenuates Angiostrongylus cantonensis-induced eosinophilic meningitis by downregulating MMP9 and TSLP proteins

Angiostrongylus cantonensis infection is a major cause of eosinophilic meningitis (EM). Severe cases or cases that involve infants and children present poor prognoses. MicroRNAs (miRNAs), which are important regulators of gene expression in many biological processes, were recently found to be regulators of the host response to infection by parasites; however, their roles in brain inflammation caused by A. cantonensis are still unclear. The current study confirmed that miR-155-5p peaked at 21 days after A. cantonensis infection, and its expression was positively correlated with the concentration of excretory and secretory products (ESPs). We found that miR-155-5p knockdown lentivirus successfully ameliorated brain injury and downregulated the expression of major basic protein (MBP) in vivo, and the number of eosinophils in CSF (and the percentage of eosinophils in peripheral blood were also decreased in the miR-155-5p knockdown group. Moreover, the expression of several eosinophilic inflammation cytokines such as CCL6/C10, ICAM-1, and MMP9, declined after the miR-155-5p knockdown. SOCS1 protein, which is an important negative regulator of inflammation activation, was identified as a direct miR-155-5p target. We further detected the effect of miR-155-5p knockdown on phosphorylated-STAT3 and phosphorylated-p65 proteins, which were found to be negatively regulated by SOCS1 and play an important role in regulating the inflammatory response. We found that miR-155-5p knockdown decreased the activity of p-STAT3 and p-p65, thereby leading to lower expression of MMP9 and TSLP proteins, which were closely related to the chemotaxis and infiltration of eosinophils. Interestingly, the inhibition of p-STAT3 or p-p65 was found to induce the downregulation of miR-155-5p in an opposite manner. These observations suggest that a positive feedback loop was formed between miR-155-5p, STAT3, and NF-κB in A. cantonensis infection and that miR-155-5p inhibition might provide a novel strategy to attenuate eosinophilic meningitis.

MicroRNA-499 Suppresses the Growth of Hepatocellular Carcinoma by Downregulating Astrocyte Elevated Gene-1

The aim of this study is to investigate the role of microRNA-499 (miR-499) in hepatocellular carcinoma tumor growth and the underlying molecular mechanisms. The expression of miR-499 was significantly decreased in hepatocellular carcinoma tissues compared with that in adjacent normal tissues. Furthermore, miR-499 overexpression in HEPG2 cell was related to the tumor growth in nude mice xenograft models. Likewise, miR-499 mimic or inhibitor decreased or accelerated cell proliferation, respectively. Mechanistically, miR-499 directly targeted the 3'- untranslated region of astrocyte elevated gene-1 and downregulate astrocyte elevated gene-1 expression. Restoration of astrocyte elevated gene-1 expression in hepatocellular carcinoma cells reversed the inhibitory effect of miR-499 on cell growth. In addition, astrocyte elevated gene-1 and miR-499 expression were inversely correlated in human and mice hepatocellular carcinoma tissues. Our study identified miR-499 as a tumor-suppressive miR in hepatocellular carcinoma, thus providing a candidate therapeutic target for the future diagnosis or treatment of hepatocellular carcinoma.

Hsa-let-7b Suppresses Cell Proliferation by Targeting UHRF1 in Melanoma

UHRF1 promotes melanoma progression by inducing cell proliferation, and is correlated with poor prognosis of melanoma patients. However, the regulation mechanism has not been fully elaborated. Here, we detected hsa-let-7b expression and its role in melanoma. Through Targetscan and miRanda predication, 30 overlapped miRNAs were found; further survival analysis revealed that hsa-let-7b was the only miRNA that affected the overall survival. Overexpressed hsa-let-7b could significantly inhibit the proliferation ability of A375 and A2058 cells, and this phenomenon was reversed after co-transfection with pLenti-UHRF1. In conclusion, hsa-let-7b regulates melanoma cells proliferation in vitro by targeting UHRF1.

LncRNA XIST promotes pancreatic cancer migration, invasion and EMT by sponging miR-429 to modulate ZEB1 expression

Pancreatic cancer (PC) has become a worldwide malignancy accompanied by high metastasis and extremely poor prognosis. The critical roles of long non-coding RNAs (lncRNAs) in PC are generally summarized as molecular sponges of microRNAs (miRNAs). We intended to investigate the biological function and mechanism of lncRNA X-inactive specific transcript (XIST) in PC progression, especially in PC cell migration and invasion. qPCR was applied to detect the expression levels of XIST and miR-429 in PC tissues and cell lines. The roles of XIST and miR-429 on PC cell migration, invasion and epithelial-mesenchymal transition (EMT) were assessed by wound healing, transwell, qPCR and Western blot assays, respectively. The regulating relationship among XIST, miR-429 and zinc finger E-box binding homeobox 1 (ZEB1) was investigated in PC cells. XIST was frequently upregulated while miR-429 was commonly downregulated in PC tissues, especially in metastatic PC tissues. Knockdown of XIST in two PC cell lines caused inhibition of migration, invasion and EMT capacities. Forced expression of miR-429 exerted the similar tumor suppressing effects. XIST repressed miR-429 expression thus upregulated ZEB1, one of the targets of miR-429. ZEB1 mediated the tumor suppressing roles of XIST knockdown in PC cells. We identified the critical axis of XIST/miR-429/ZEB1 in PC cell migration, invasion and EMT, which may aid in developing new therapeutic strategies for PC.

The protean world of non-coding RNAs in glioblastoma

Non-coding ribonucleic acids (ncRNAs) are a diverse group of RNA molecules that are mostly not translated into proteins following transcription. We review the role of ncRNAs in the pathobiology of glioblastoma (GBM), and their potential applications for GBM therapy. Significant advances in our understanding of the protean manifestations of ncRNAs have been made, allowing us to better decipher the molecular complexity of GBM. A large number of regulatory ncRNAs appear to have a greater influence on the molecular pathology of GBM than thought previously. Importantly, also, a range of therapeutic approaches are emerging whereby ncRNA-based systems may be used to molecularly target GBM. The most successful of these is RNA interference, and some of these strategies are being evaluated in ongoing clinical trials. However, a number of limitations exist in the clinical translation of ncRNA-based therapeutic systems, such as delivery mechanisms and cytotoxicity; concerted research endeavors are currently underway in an attempt to overcome these. Ongoing and future studies will determine the potential practical role for ncRNA-based therapeutic systems in the clinical management of GBM. These applications may be especially promising, given that current treatment options are limited and prognosis remains poor for this challenging malignancy.

Pre-operative Plasma miR-21-5p Is a Sensitive Biomarker and Independent Prognostic Factor in Patients with Pancreatic Ductal Adenocarcinoma Undergoing Surgical Resection

Blood plasma microRNAs (miRNAs) are emerging as a clinically useful tool for non-invasive detection and prognosis estimation in various cancer types including pancreatic ductal adenocarcinoma (PDAC). The aim of the present study was to provide an independent validation of circulating miRNAs identified in previous studies as diagnostic and/or prognostic biomarkers in PDAC. Based on the literature search, 6 miRNAs were chosen as candidates for independent validation; miR-21-5p, miR-375, miR-155, miR-17-5p, miR-126-5p and miR-1290. Validation of these miRNAs was performed in a cohort of 25 patients with PDAC undergoing surgical resection and 24 healthy donors. Plasma levels of miRNAs were determined using quantitative real-time PCR. We confirmed significantly higher levels of all tested miRNA in blood plasma of PDAC patients in comparison to healthy controls with miR-21-5p showing the highest analytical performance (p<0.001; AUC>0.99). Increased levels of miR-21-5p (p=0.045) and miR-375 (p=0.013) were significantly associated with overall survival. Multivariate analysis demonstrated that miR-21-5p is a significant unfavorable prognostic factor independent on other clinical variables including adjuvant chemotherapy (hazard ratio 2.95; 95% CI 1.06-8.18; p=0.038). Our preliminary data indicate promising diagnostic and prognostic utility of plasma miR-21-5p in PDAC patients.

Upregulated miR-221/222 promotes cell proliferation and invasion and is associated with invasive features in retinoblastoma

BACKGROUND AND OBJECTIVES

MicroRNA (miR-221/222) is frequently overexpressed in many cancers and is associated with poor prognosis. However, the role of miR-221/222 in retinoblastoma (RB) remains unclear. This study aimed to detect the clinical significance of miR-221/222 in RB patients and explore its role in RB cells in vitro.

METHODS

Expression of miR-221/222 was assessed in fresh RB tissue collected from 64 eyes and normal retinal tissues from 18 unrelated donor cadaver eyes by quantitative real time RT-PCR analysis (qRT-PCR), and correlated with the histopathological findings. Human RB Y79 cells were transfected with miR-221/222 precursors or inhibitors to overexpress or downregulate miR-221/222 expression, respectively, using Lipofectamine 2000 reagent. The biological effects of miR-221/222 were then assessed by cell viability assays, colony formation assays, apoptosis detection assays, Matrigel® invasion assays, and wound-healing assays.

RESULTS

Higher miR-221/222 expression was detected in RB tissues compared to that of the normal retinal tissues (p< 0.001). Higher miR-221/222 expression was correlated with invasion in patients with RB. Targeting of miR-221/222 induced apoptosis and inhibited Y79 cell proliferation, migration, and invasion in vitro. However, overexpression of miR-221/222 promoted Y79 cell proliferation, migration, and invasion in vitro.

CONCLUSIONS

Overexpression of miR-221/222 was associated with tumor invasiveness in patients with RB. The miR-221/222 cluster might be used as a potential therapeutic strategy in clinical practice.

Targeting of G-Quadruplex Harboring Pre-miRNA 92b by LNA Rescues PTEN Expression in NSCL Cancer Cells

Since the elevated levels of microRNAs (miRNAs) often cause various diseases, selective inhibition of miRNA maturation is an important therapeutic strategy. Commonly used anti-miRNA strategies are limited to targeting of mature miRNAs, as the upstream targeting of miRNA maturation with an oligonucleotide is challenging due to the presence of a stable pre-miRNA stem-loop structure. Previously, we reported that about 16% of known human pre-miRNAs have the potential to adopt G-quadruplex (GQ) structures alternatively to canonical stem-loops. Herein, we showed that a rationally designed locked nucleic acid (LNA) binds specifically the GQ conformation of pre-miRNA 92b and inhibits pre-miRNA maturation. Further, we showed that the LNA treatment rescues PTEN expression in non-small-cell lung cancer (NSCLC) cells, which is suppressed by the elevated level of miRNA 92b. Treatment of LNA significantly decreases the IC₅₀ of doxorubicin for NSCLC cells. This strategy can be developed as a novel anti-miRNA therapeutic approach to target GQ harboring miRNAs. This can potentially be a more powerful approach than targeting of the mature miRNA, as it is an upstream targeting and can reduce both 3' and the 5' mature miRNA levels at once.

The association of polymorphisms in miRNAs with nonsmall cell lung cancer in a Han Chinese population

Background

MicroRNAs (miRNAs) have been demonstrated to play important roles in cancer progression. Recently, studies have revealed that polymorphisms in miRNAs might be associated with cancer susceptibility.

Materials and methods

In the current study, we investigated the associations of single nucleotide polymorphisms (SNPs) in miRNAs (rs11134527 in pri-miR-218-2, rs74693964 in pri-miR-145, rs6062251 in pri-miR-133a-2, and rs4705343 in pri-miR-143) with nonsmall cell lung cancer (NSCLC) in a Han population from Yunnan Province, Southwest China using a binary logistic regression analysis. A total of 452 patients with NSCLC and 452 healthy individuals were recruited for polymorphism genotyping using the TaqMan assay.

Results

Our results showed that the allelic frequencies of rs11134527 and rs4705343 were significantly different between the NSCLC and control groups (P=0.025 and 0.029). Additionally, the genotypic frequencies of rs11134527 were significantly different between the NSCLC and control groups (P=0.045). The mode of inheritance analysis showed that genotypes A/G+G/G of rs11134527 were associated with a lower risk of NSCLC under the dominant model (OR=0.69; 95% CI: 0.51–0.94). In addition, genotypes 2C/C+C/T of rs4705343 were associated with an increased risk of NSCLC under the log-additive model (OR=1.25; 95% CI: 1.01–1.53). However, there was no significant difference in the other SNPs between the NSCLC and control groups (P>0.05). Moreover, the association analysis of these SNPs between adenocarcinoma and squamous cell carcinoma (SCC) showed that allele A of rs11134527 was associated with SCC (OR=0.65; 95% CI: 0.48–0.88).

Conclusion

Our results indicated that the A allele of rs11134527 might be a risk factor (OR=1.24; 95% CI: 1.03–1.50) and that the T allele of rs4705343 might be a protective factor (OR=0.80; 95% CI: 0.66–0.98) for NSCLC in a Han Chinese population.

Tumor-Suppressive MicroRNA-708 Targets Notch1 to Suppress Cell Proliferation and Invasion in Gastric Cancer

Growing evidence has demonstrated that numerous microRNAs (miRNAs) may participate in the regulation of gastric carcinogenesis and progression. This phenomenon suggests that gastric cancer-related miRNAs can be identified as effective therapeutic targets for this disease. miRNA-708 (miR-708) has recently been reported to be aberrantly expressed in several types of cancer and contribute to carcinogenesis and progression. However, the expression level, biological roles, and underlying mechanisms of miR-708 in gastric cancer are poorly understood. Here we found that miR-708 was downregulated in gastric cancer tissues and cell lines. Downregulated miR-708 expression was significantly associated with lymphatic metastasis, invasive depth, and TNM stage. Further investigation indicated that ectopic expression of miR-708 prohibited cell proliferation and invasion in gastric cancer. Bioinformatics analysis showed that Notch1 was a potential target of miR-708. Notch1 was further confirmed as a direct target gene of miR-708 in gastric cancer by dual-luciferase reporter assay, reverse transcription quantitative polymerase chain reaction, and Western blot analysis. Furthermore, an inverse association was found between miR-708 and Notch1 mRNA levels in gastric cancer tissues. In addition, restored Notch1 expression rescued the inhibitory effects on gastric cancer cell proliferation and invasion induced by miR-708 overexpression. Our findings highlight the tumor-suppressive roles of miR-708 in gastric cancer and suggest that miR-708 may be investigated as a novel target for gastric cancer treatment.

MicroRNAs in cancer metastasis and angiogenesis

Cancer metastasis is a malignant process by which tumor cells migrate from their primary site of origin to other organs. It is the main cause of poor prognosis in cancer patients. Angiogenesis is the process of generating new blood capillaries from pre-existing vasculature. It plays a vital role in primary tumor growth and distant metastasis. MicroRNAs are small non-coding RNAs involved in regulating normal physiological processes as well as cancer pathogenesis. They suppress gene expression by specifically binding to the 3′-untranslated region (3′-UTR) of their target genes. They can thus act as oncogenes or tumor suppressors depending on the function of their target genes. MicroRNAs have shown great promise for use in anti-metastatic cancer therapy. In this article, we review the roles of various miRNAs in cancer angiogenesis and metastasis and highlight their potential for use in future therapies against metastatic cancer.

miR-519d Promotes Melanoma Progression by Downregulating EphA4

Increasing evidence suggests that there is a unique cell subpopulation in melanoma that can form nonadherent melanospheres in serum-free stem cell medium, mimicking aggressive malignancy. Using melanospheres as a model to investigate progression mechanisms, we found that miR-519d overexpression was sufficient to promote cell proliferation, migration, invasion, and adhesion in vitro and lung metastatic capability in vivo The cell adhesion receptor EphA4 was determined to be a direct target of miR-519d. Forced expression of EphA4 reversed the effects of miR-519d overexpression, whereas silencing of EphA4 phenocopied the effect of miR-519d. Malignant progression phenotypes were also affected at the level of epithelial-to-mesenchymal transition and the ERK1/2 signaling pathway inversely affected by miR-519d or EphA4 expression. In clinical specimens of metastatic melanoma, we observed significant upregulation of miR-519d and downregulation of EphA4, in the latter case correlated inversely with overall survival. Taken together, our results suggest a significant functional role for miR-519d in determining EphA4 expression and melanoma progression.Significance: These results suggest a significant role for miR-519d in determining expression of a pivotal cell adhesion molecule that may impact risks of malignant progression in many cancers. Cancer Res; 78(1); 216-29. ©2017 AACR.

The association between polymorphisms in microRNA genes and cervical cancer in a Chinese Han population

Several studies have confirmed the crucial roles of microRNAs (miRNAs) in cancer occurrence. In addition, single nucleotide polymorphisms (SNPs) in miRNA genes have been associated with various cancers. The aim of the present study was to investigate the association of SNPs in miRNA genes with cervical intraepithelial neoplasia (CIN) and cervical cancer in a Chinese Han population. We searched SNPs in nineteen miRNAs by sequencing healthy individuals (n=50). Then, a total of 400 patients with CIN, 609 patients with cervical cancer and 583 healthy individuals were recruited to genotype the SNPs using a Taqman assay. The results showed that only five of the nineteen miRNAs had SNPs (rs11134527 in pri-miR-218-2; rs74693964 in pri-miR-145; rs6062251 in pri-miR-133a2; rs531564 in pri-miR-124-1; and rs1834306 in pri-miR-100) in this Chinese Han population. The frequency of the rs11134527A allele was significantly higher in the control group than in CIN and cervical cancer groups (P=0.011 and 0.035, respectively). The frequency of the rs531564G allele was higher in the CIN and control groups than in the cervical cancer group (P=0.019 and 0.017, respectively). These results indicated that rs11134527 in pri-miR-218-2 and rs531564 in pri-miR-124-1 could be associated with CIN and cervical cancer in the Chinese Han population.

MicroRNA‑494 inhibits nerve growth factor‑induced cell proliferation by targeting cyclin D1 in human corneal epithelial cells

Nerve growth factor (NGF) is expressed in the human corneal epithelium and stroma. It is an efficient therapy for human corneal ulcers caused by neurotropic disease. However, little is known about the molecular mechanism of NGF in healing human corneal epithelial diseases. Numerous microRNAs (miRNAs) are expressed in the cornea and miRNAs have important roles in regulating corneal development. In the present study, novel miRNA regulators were demonstrated to be involved in NGF‑induced human corneal epithelial cell (hCEC) proliferation. NGF treatment significantly downregulated the expression of miRNA‑494 in hCECs in vitro. Furthermore, miRNA‑494 increased G1 arrest in the immortalized human corneal epithelial cell (ihCEC) line and suppressed cell proliferation. Accordingly, bioinformatics programs and luciferase reporter assay demonstrated that miRNA‑494 directly targeted cyclin D1 by binding to a sequence in the 3'‑untranslated region. In addition, overexpression of miRNA‑494 decreased both basal and NGF‑induced cyclin D1 expression. NGF treatment partially suppressed miRNA‑494 expression and restored cyclin D1 expression. Furthermore, co‑transfection of miRNA‑494 with the cyclin D1 ORF clone partially restored cyclin D1 mRNA and protein expression. These findings indicate that miRNA‑494 and its target cyclin D1 may be a crucial axis for NGF in regulating the proliferation of hCEC. Specific modulation of miRNA‑494 in hCEC could represent an attractive approach for treating cornea epithelial diseases.

Noncoding RNA in drug resistant sarcoma

Sarcomas are a group of malignant tumors that arise from mesenchymal origin. Despite significant development of multidisciplinary treatments for sarcoma, survival rates have reached a plateau. Chemotherapy has been extensively used for sarcoma treatment; however, the development of drug resistance is a major obstacle limiting the success of many anticancer agents. Sarcoma biology has traditionally focused on genomic and epigenomic deregulation of protein-coding genes to identify the therapeutic potential for reversing drug resistance. New and more creative approaches have found the involvement of noncoding RNAs, including microRNAs and long noncoding RNAs in drug resistant sarcoma. In this review, we discuss the current knowledge of noncoding RNAs characteristics and the regulated genes involved in drug resistant sarcoma, and focus on their therapeutic potential in the future.

MicroRNA-296-5p Promotes Invasiveness through Downregulation of Nerve Growth Factor Receptor and Caspase-8

Glioblastomas (GBM) are very difficult to treat and their aggressiveness is one of the main reasons for this as well as for the frequent recurrences. MicroRNAs post-transcriptionally regulate their target genes through interaction between their seed sequence and 3'UTR of the target mRNAs. We previously reported that miR-296-3p is regulated by neurofibromatosis 2 (NF2) and enhances the invasiveness of GBM cells via SOCS2/STAT3. In this study, we investigated whether miR-296-5p, which originates from the same precursor miRNA as miR-296-3p, can increase the invasiveness of GBM cells. It was observed that miR-296-5p potentiated the invasion of various GBM cells including LN229, T98G, and U87MG. Through bioinformatics approaches, two genes were identified as miR-296-5p targets: caspase-8 (CASP8) and nerve growth factor receptor (NGFR). From results obtained from Ago2 immunoprecipitation and luciferase assays, we found that miR-296-5p downregulates CASP8 and NGFR through direct interaction between seed sequence of the miRNA and 3'UTR of the target mRNA. Knockdown of CASP8 or NGFR also increased the invasive ability of GBM cells, indicating that CASP8 and NGFR are involved in potentiation of invasiveness by miR-296-5p. Consistent with our findings, CASP8 was downregulated in brain metastatic lung cancer cells, which have a high level of miR-296-5p, compared to parental cells, suggesting that miR-296-5p may be generally associated with the acquisition of invasiveness. Collectively, our results implicate miR-296-5p as a potential cause of invasiveness in cancer and suggest it as a promising therapeutic target for GBM.

miR-10b exerts oncogenic activity in human hepatocellular carcinoma cells by targeting expression of CUB and sushi multiple domains 1 (CSMD1)

BACKGROUND

Hepatocellular carcinoma (HCC) is a lethal disease, while the precise underlying molecular mechanisms of HCC pathogenesis remain to be defined. MicroRNA (miRNA), a class of non-coding small RNAs, can post-transcriptionally regulate gene expression. Altered miRNA expression has been reported in HCCs. This study assessed expression and the oncogenic activity of miRNA-10b (miR-10b) in HCC.

METHODS

Forty-five paired human HCC and adjacent non-tumor tissues were collected for qRT-PCR and immunohistochemistry analysis of miR-10b and CUB and Sushi multiple domains 1 (CSMD1), respectively. We analyzed the clinicopathological data from these patients to further determine if there was an association between miR-10b and CSMD1. HCC cell lines were used to assess the effects of miR-10b mimics or inhibitors on cell viability, migration, invasion, cell cycle distribution, and colony formation. Luciferase assay was used to assess miR-10b binding to the 3'-untranslated region (3'-UTR) of CSMD1.

RESULTS

miR-10b was highly expressed in HCC tissues compared to normal tissues. In vitro, overexpression of miR-10b enhanced HCC cell viability, migration, and invasion; whereas, downregulation of miR-10b expression suppressed these properties in HCC cells. Injection of miR-10b mimics into tumor cell xenografts also promoted xenograft growth in nude mice. Bioinformatics and luciferase reporter assay demonstrated that CSMD1 was the target gene of miR-10b. Immunocytochemical, immunohistochemical, and qRT-PCR data indicated that miR-10b decreased CSMD1 expression in HCC cells.

CONCLUSIONS

We showed that miR-10b is overexpressed in HCC tissues and miR-10b mimics promoted HCC cell viability and invasion via targeting CSMD1 expression. Our findings suggest that miR-10b acts as an oncogene by targeting the tumor suppressor gene, CSMD1, in HCC.

Inhibition of MicroRNA miR-222 with LNA Inhibitor Can Reduce Cell Proliferation in B Chronic Lymphoblastic Leukemia

MicroRNAs (miRNAs) are small regulatory molecules that negatively regulate gene expression by base-pairing with their target mRNAs. miRNAs have contribute significantly to cancer biology and recent studies have demonstrated the oncogenic or tumor-suppressing role in cancer cells. In many tumors up-regulation miRNAs has been reported especially miR-222 has been shown to be up-regulated in B chronic lymphocytic leukemia (B-CLL). In this study we assessed the effected inhibition of miR-222 in cell viability of B-CLL. We performed inhibition of mir-222 in B-CLL cell line (183-E95) using locked nucleic acid (LNA) antagomir. At different time points after LNA-anti-mir-222 transfection, miR-222 quantitation and cell viability were assessed by qRT-real time polymerase chain reaction and MTT assays. The data were analyzed by independent t test and one way ANOVA. Down-regulation of miR-222 in B-CLL cell line (183-E95) with LNA antagomir decreased cell viability in B-CLL. Cell viability gradually decreased over time as the viability of LNA-anti-mir transfected cells was <47 % of untreated cells at 72 h post-transfection. The difference in cell viability between LNA-anti-miR and control groups was statistically significant (p < 0.042). Based on our findings, the inhibition of miR-222 speculate represent a potential novel therapeutic approach for treatment of B-CLL.

MicroRNA-210 induces apoptosis in colorectal cancer via induction of reactive oxygen

Background

Deregulation of miRNA-210 is a common event in several types of cancer. However, increased expression levels in the cancer tissue have been associated with both poor and good prognosis of patients. Similarly, the function of miR-210 with regard to cell growth and apoptosis is still controversial.

Methods

Overexpression of miR-210 was performed in HCT116, SW480 and SW707 colorectal cancer (CRC) cell lines. Functional effects of a modulated miR-210 expression were analyzed with regard to proliferation, clonogenicity, cell cycle distribution, reactive oxygen species (ROS) generation, and apoptosis. Furthermore, quantitative real time (RT)-PCR and immunoblot analyses were performed to investigate signaling pathways affected by miR-210.

Results

We show that in CRC cells miR-210 inhibits clonogenicity and proliferation which was accompanied by an accumulation of cells in the G2/M phase of the cell cycle. Additionally, overexpression of miR-210 results in an increase of ROS generation. Moreover, miR-210 mediated the induction of apoptosis which was associated with an upregulation of pro-apoptotic Bim expression and enhanced processing of Caspase 2. Importantly, inhibition of ROS generation rescued cells from miR-210-induced apoptosis.

Conclusions

Taken together, miR-210 induces apoptosis in CRC cells via a ROS-dependent mechanism.

Electronic supplementary material

The online version of this article (doi:10.1186/s12935-016-0321-6) contains supplementary material, which is available to authorized users.

Screening of Differently Expressed miRNA and mRNA in Prostate Cancer by Integrated Analysis of Transcription Data

OBJECTIVE

The purpose of this study was to screen aberrantly expressed miRNAs and genes in prostate cancer (PCA), and further uncover the underlying mechanisms for the development of PCA.

MATERIALS AND METHODS

We searched the Gene Expression Omnibus database for miRNA and gene expression datasets of PCA, and then separately integrated miRNA and gene expression datasets to identify miRNA and gene expression profiles in PCA. Target genes of differentially expressed miRNAs were predicted through miRWalk database. We matched these target genes with the list of differentially expressed genes to identify miRNA-target gene pairs whose expression was inversely correlated. The function of these target genes was annotated.

RESULTS

Twenty-nine differentially expressed miRNAs and 946 differentially expressed genes were identified between PCA and normal control. Seven hundred fifty-one miRNA-target gene pairs that showed inverse expression in PCA were obtained to establish a regulatory network. In this regulatory network, 10 genes (BCL2, BNC2, CCND2, EPM2A, MRAS, NAV2, RASL12, STK33, TCEAL1, WWC2) were co-regulated by 5 miRNAs (hsa-miR-106b, hsa-miR-130b, hsa-miR-93, hsa-miR-153, hsa-miR-182). The expression of hsa-miR-182 was significantly associated with PCA survival through the online validation tool of SurvMicro, suggesting the potential use as a diagnostic or prognostic biomarker in PCA.

CONCLUSION

This integrated analysis was performed to infer new miRNA regulation activities, which provides insights into the understanding of underlying molecular mechanisms of PCA, and guides for exploration of novel therapeutic targets.

Circulating MicroRNA-26a in Plasma and Its Potential Diagnostic Value in Gastric Cancer

BACKGROUND

In the past decades, a good deal of studies has provided the possibility of the circulating microRNAs (miRNAs) as noninvasive biomarkers for cancer diagnosis. The aim of our study was to detect the levels of circulating miRNAs in tissues and plasmas of gastric cancer (GC) patients and evaluate their diagnostic value.

METHODS

Tissue samples were collected from 85 GC patients. Plasma samples were collected from 285 GC patients and 285 matched controls. Differentially expressed miRNAs were filtered with by Agilent Human miRNA Microarray and TaqMan low density array (TLDA) with pooled samples, followed by the quantitative reverse transcription polymerase chain reaction (qRT-PCR) validation. Receiver operating characteristic (ROC) curves were structured to evaluate the diagnostic accuracy of the miRNAs. The plasma level of miR-26a in GC patients of different clinical stages was compared.

RESULTS

Four miRNAs (miR-26a, miR-142-3p, miR-148a, and miR-195) revealed coincidentally decreased levels in tissue and plasma of the GC patients compared with controls, and ROC curves were constructed to demonstrate that miR-26a had a highest area under the ROC curve (AUC) of 0.882. Furthermore, miR-26a was stably detected in the plasma of GC patients with different clinical characteristics.

CONCLUSION

Plasma miR-26a may provide a novel and stable marker of gastric cancer.

RUNX3 is down-regulated in glioma by Myc-regulated miR-4295

MicroRNAs are increasingly reported as tumour suppressors that regulate gene expression after transcription. Our results demonstrated that miR-4295 is overexpression in glioma tissues and its level is significantly correlated with clinical stage. We also found that miR-4295 inhibited the cell G0/G1 arrest and apoptosis leading to promoted cell proliferation and activity. The murine modelling study revealed that female nude mice injected with U87/anti-miR-4295 exhibit subcutaneous tumours in the right groin. Compared with anti-NC, the tumour volume was significantly decreased in anti-miR-4295 treatment group. Furthermore, we confirmed miR-4295 mediates the expression of RUNX3 by targeting its 3'untranslation region. In addition, N-myc protein also could bind to the promoter of pri-miR-4295 and inhibit the expression of RUNX3 in glioma cells. These results validate a pathogenetic role of a miR-4295 in gliomas and establish a potentially regulatory and signalling pathway involving N-myc/miR-4295/RUNX3 in gliomas.

The prognostic effect of PTEN expression status in colorectal cancer development and evaluation of factors affecting it: miR-21 and promoter methylation

BACKGROUND

PTEN is a tumor suppressor gene which is involved in cellular proliferation, differentiation, and apoptosis. Loss or down-regulation of PTEN plays an important role in human cancers development. In this study, we investigated the effect of miR-21 and promoter methylation on the PTEN expression status in CRC tissues and analyzed association of the PTEN expression status with clinicopathological features in patients with CRC.

RESULTS

The PTEN expression was positively detected in 67.2 % CRC tissues and all adjacent non-cancerous samples. PTEN mRNA level was negatively correlated with miR-21 level (r = -0.595, P < 0.001). PTEN expression was also correlated directly with the PTEN mRNA level (r = 0.583, P < 0.001) and conversely with miR-21 level (r = -0.632, P < 0.001). PTEN Promoter methylation was significantly associated with PTEN expression status (p = 0.013). PTEN expression was negatively associated with tumor size (p = 0.007) and advanced tumor stage (P = 0.011). Multivariate analysis indicated that tumor stage, tumor differentiation and PTEN expression status were independent prognostic factors for overall carcinoma in CRC patients (P < 0.05). The Kaplan-Meier curve indicated a negative correlation between PTEN expression levels and survival of CRC patients (P = 0.013).

CONCLUSIONS

This study suggests a high frequency of miR-21 overexpression and aberrant promoter methylation in down-regulation of PTEN expression in colorectal carcinoma. Loss of PTEN may be a prognostic factor for patients with CRC.

MiRNAs and Other Epigenetic Changes as Biomarkers in Triple Negative Breast Cancer

Triple negative breast cancer (TNBC) is characterised by the lack of receptors for estrogen (ER), progesterone (PR), and human epidermal growth factor 2 (HER2). Since it cannot be treated by current endocrine therapies which target these receptors and due to its aggressive nature, it has one of the worst prognoses of all breast cancer subtypes. The only treatments remain chemo- and/or radio-therapy and surgery and because of this, novel biomarkers or treatment targets are urgently required to improve disease outcomes. MicroRNAs represent an attractive candidate for targeted therapies against TNBC, due to their natural ability to act as antisense interactors and regulators of entire gene sets involved in malignancy and their superiority over mRNA profiling to accurately classify disease. Here we review the current knowledge regarding miRNAs as biomarkers in TNBC and their potential use as therapeutic targets in this disease. Further, we review other epigenetic changes and interactions of these changes with microRNAs in this breast cancer subtype, which may lead to the discovery of new treatment targets for TNBC.

HPVbase--a knowledgebase of viral integrations, methylation patterns and microRNAs aberrant expression: As potential biomarkers for Human papillomaviruses mediated carcinomas

Human papillomaviruses (HPVs) are extremely associated with different carcinomas. Despite consequential accomplishments, there is still need to establish more promising biomarkers to discriminate cancerous progressions. Therefore, we have developed HPVbase (http://crdd.osdd.net/servers/hpvbase/), a comprehensive resource for three major efficacious cancer biomarkers i.e. integration and breakpoint events, HPVs methylation patterns and HPV mediated aberrant expression of distinct host microRNAs (miRNAs). It includes clinically important 1257 integrants and integration sites from different HPV types i.e. 16, 18, 31, 33 and 45 associated with distinct histological conditions. An inclusive HPV integrant and breakpoints browser was designed to provide easy browsing and straightforward analysis. Our study also provides 719 major quantitative HPV DNA methylation observations distributed in 5 distinct HPV genotypes from higher to lower in numbers namely HPV 16 (495), HPV 18 (113), HPV45 (66), HPV 31 (34) and HPV 33 (11). Additionally, we have curated and compiled clinically significant aberrant expression profile of 341 miRNAs including their target genes in distinct carcinomas, which can be utilized for miRNA therapeutics. A user-friendly web interface has been developed for easy data retrieval and analysis. We foresee that HPVbase an integrated and multi-comparative platform would facilitate reliable cancer diagnostics and prognosis.

Characterization of the mammalian miRNA turnover landscape

Steady state cellular microRNA (miRNA) levels represent the balance between miRNA biogenesis and turnover. The kinetics and sequence determinants of mammalian miRNA turnover during and after miRNA maturation are not fully understood. Through a large-scale study on mammalian miRNA turnover, we report the co-existence of multiple cellular miRNA pools with distinct turnover kinetics and biogenesis properties and reveal previously unrecognized sequence features for fast turnover miRNAs. We measured miRNA turnover rates in eight mammalian cell types with a combination of expression profiling and deep sequencing. While most miRNAs are stable, a subset of miRNAs, mostly miRNA*s, turnovers quickly, many of which display a two-step turnover kinetics. Moreover, different sequence isoforms of the same miRNA can possess vastly different turnover rates. Fast turnover miRNA isoforms are enriched for 5′ nucleotide bias against Argonaute-(AGO)-loading, but also additional 3′ and central sequence features. Modeling based on two fast turnover miRNA*s miR-222-5p and miR-125b-1-3p, we unexpectedly found that while both miRNA*s are associated with AGO, they strongly differ in HSP90 association and sensitivity to HSP90 inhibition. Our data characterize the landscape of genome-wide miRNA turnover in cultured mammalian cells and reveal differential HSP90 requirements for different miRNA*s. Our findings also implicate rules for designing stable small RNAs, such as siRNAs.

Quercetin inhibits proliferation and invasion acts by up-regulating miR-146a in human breast cancer cells

Breast cancer is the most common female malignancies in the world which seriously impacts the female health. In recent years, various studies have been reported to determine the relevance of miRNAs to human cancer. One of these miRNAs, miR-146a has been down-regulated in multiple human cancer types, but up-regulation showed inducing apoptosis. To determine the role of quercetin treated on breast cancer, we investigated the effect of quercetin on cell proliferation in human breast cancer cell lines MCF-7 and MDA-MB-231 with/without transfection of miR-146a mimic or anti-miR-146a. Furthermore, the expressions of bax and cleaved-caspase-3, mainly were increased in control and overexpression miR-146a groups, however, the expression of EGFR was inverse. All the results demonstrated that quercetin exhibited excellent effect on inhibiting cell proliferation in human breast cancer cells, which was performed by up-regulating miR-146a expression, then via inducing apoptosis through caspase-3 activation and mitochondrial-dependent pathways, and inhibiting invasion through down-regulating the expression of EGFR.