Role of microRNAs in translation regulation and cancer

microRNA-485-5p Functions as a Tumor Suppressor in Colorectal Cancer Cells by Targeting CD147

Colorectal cancer(CRC) is a prevalent malignancy in the world. There is growing evidence that microRNAs (miRNAs) as crucial modulator are in connection with many tumor-related diseases including CRC. Though miR-485-5p has been reported as an anti-oncogene in certain cancers, it remains unclear in CRC. In this research, we found that miR-485-5p was at lower level expression in CRC tissues and cell lines compared to the paired paracancerous tissues and the normal colon epithelial cell line FHC, correspondingly. Furthermore, Experimental up-regulation miR-485-5p in DLD-1 and SW480 cells with mimic could inhibit the ability of proliferation, migration, invasion of CRC cell lines and facilitate cells apoptosis. Also, we confirmed that CD147 existed typically negative regulation by miR-485-5p through binding a conserved sequence specifically within the CD147 3'-untranslated region (3'UTR) and reintroduction of CD147 could rescue the phenotypic changes caused by miR-485-5p. The findings provide evidence to demonstrate the role of miR-485-5p/CD147 interaction in CRC and indicate that miR-485-5p might be exploited therapeutically in CRC.

New emerging roles of microRNAs in breast cancer

BACKGROUND

MicroRNAs constitute a large family of non-coding RNAs, which actively participate in tumorigenesis by regulating a set of mRNAs of distinct signaling pathways. An altered expression of these molecules has been found in different tumorigenic processes of breast cancer, the most common type of cancer in the female population worldwide.

PURPOSE

The objective of this review is to discuss how miRNAs become master regulators in breast tumorigenesis.

METHODS

An integrative review of miRNAs and breast cancer literature from the last 5 years was done on PubMed. We summarize recent works showing that the defects on the biogenesis of miRNAs are associated with different breast cancer characteristics. Then, we show several examples that demonstrate the link between cellular processes regulated by miRNAs and the hallmarks of breast cancer. Finally, we examine the complexity in the regulation of these molecules as they are modulated by other non-coding RNAs and the clinical applications of miRNAs as they could serve as good diagnostic and classification tools.

CONCLUSION

The information presented in this review is important to encourage new directed studies that consider microRNAs as a good tool to improve the diagnostic and treatment alternatives in breast cancer.

40 Years of Research Put p53 in Translation

Since its discovery in 1979, p53 has shown multiple facets. Initially the tumor suppressor p53 protein was considered as a stress sensor able to maintain the genome integrity by regulating transcription of genes involved in cell cycle arrest, apoptosis and DNA repair. However, it rapidly came into light that p53 regulates gene expression to control a wider range of biological processes allowing rapid cell adaptation to environmental context. Among them, those related to cancer have been extensively documented. In addition to its role as transcription factor, scattered studies reported that p53 regulates miRNA processing, modulates protein activity by direct interaction or exhibits RNA-binding activity, thus suggesting a role of p53 in regulating several layers of gene expression not restricted to transcription. After 40 years of research, it appears more and more clearly that p53 is strongly implicated in translational regulation as well as in the control of the production and activity of the translational machinery. Translation control of specific mRNAs could provide yet unsuspected capabilities to this well-known guardian of the genome.

Deep Sequencing of Small RNAs in Blood of Patients with Brain Arteriovenous Malformations

BACKGROUND

Deregulation of circulating microRNAs (miRNAs) is always associated with development and progression of human diseases. We aimed to assess whether patients with brain arteriovenous malformations (BAVMs) possess a distinct miRNA signature compared with healthy subjects.

METHODS

Three patients with unruptured BAVMs and 3 normal control subjects were recruited as case and control groups. Peripheral blood was collected, and miRNA signature was obtained by next-generation sequencing, followed by comparative, functional, and network analyses. Quantitative reverse transcription polymerase chain reaction was performed to validate expression of specific miRNAs.

RESULTS

Deep sequencing detected 246 differentially expressed miRNAs in blood samples of patients with BAVMs compared with normal control subjects. For the top 5 miRNAs, 946 target genes were predicted, and a BAVM-specific miRNA-target gene regulatory network was constructed. Functional annotation suggested that 15 of the predicted miRNA-targeted genes were involved in vascular endothelial growth factor signaling, in which 3 critical miRNAs were involved: miR-7-5p, miR-199a-5p, and miR-200b-3p.

CONCLUSIONS

We explored the miRNA expression signature of BAVMs, which will provide an important foundation for future studies on the regulation of miRNAs involved in BAVMs.

MicroRNA-183 suppresses the vitality, invasion and migration of human osteosarcoma cells by targeting metastasis-associated protein 1

The aim of the present study was to investigate the effects of microRNA (miR)-183 on vitality, invasion, metastasis and apoptosis in osteosarcoma (OS) cells, mediated by its binding to metastasis-associated protein 1 (MTA1). A dual luciferase reporter assay was performed to determine whether MTA1 was a direct target of miR-183. Cell Counting Kit-8, Transwell, scratch-wound healing, fluorescence-activated cell sorting andterminal deoxynucleotidyl transferase dUTP nick end labeling assays were also performed to investigate the effects of miR-183 expression on the proliferation, invasion, migration and apoptosis of MG63 cells. It was demonstrated that that MTA1 expression levels were significantly higher in OS tissues and MG63 cells compared with corresponding adjacent noncancerous tissues and normal cells, respectively, while miR-183 expression levels were significantly lower (both P<0.05). Furthermore, miR-183 overexpression downregulated MTA1 levels and inhibited cell proliferation (P<0.05), migration (P<0.05) and invasion (P<0.01), as well as promoting apoptosis (P<0.01) by binding to the 3'-untranslated region of MTA1. These results indicate that miR-183 inhibits the vitality, invasion, migration and apoptosis of the OS cell line MG63 by targeting MTA1. These findings may contribute to the development of novel clinical therapeutic approaches for the treatment of OS.

Endometriosis Malignant Transformation: Epigenetics as a Probable Mechanism in Ovarian Tumorigenesis

Endometriosis, defined as the presence of ectopic endometrial glands and stroma outside the uterine cavity, is a chronic, hormone-dependent gynecologic disease affecting millions of women across the world, with symptoms including chronic pelvic pain, dysmenorrhea, dyspareunia, dysuria, and subfertility. In addition, there is well-established evidence that, although endometriosis is considered benign, it is associated with an increased risk of malignant transformation, with the involvement of various mechanisms of development. More and more evidence reveals an important contribution of epigenetic modification not only in endometriosis but also in mechanisms of endometriosis malignant transformation, including DNA methylation and demethylation, histone modifications, and miRNA aberrant expressions. In this present review, we mainly summarize the research progress about the current knowledge regarding the epigenetic modifications of the relations between endometriosis malignant transformation and ovarian cancer in an effort to identify some risk factors probably associated with ectopic endometrium transformation.

MicroRNAs in type 1 diabetes: new research progress and potential directions

MicroRNAs (miRNAs) are a class of noncoding single-stranded RNA molecules encoded by endogenous genes of about 22 nucleotides, which are involved in post-transcriptional gene expression regulation in animals and plants. Type 1 diabetes (T1D) is an autoimmune disease that is clinically silent until the majority of β cells are destroyed, and a large number of studies have shown that miRNAs are involved in the pathological mechanism of T1D. In this review, we searched the related research in recent years and summarized the important roles of miRNAs in T1D diagnosis and treatment. Furthermore, we summarized the current understanding of miRNA-mediated regulation mechanisms of gene expression in the T1D pathogenesis as well as related signaling pathways with a focus on the important roles of miRNAs and their antagonists in T1D pathogenesis, and brought insight into the potential therapeutic value of miRNAs for T1D patients. In view of the important roles of miRNAs in T1D pathology, disordered miRNAs may be important diagnostic markers and therapeutic targets for patients with T1D.

miR-622 suppresses tumor formation by directly targeting VEGFA in papillary thyroid carcinoma

Background

MicroRNAs (miRNAs) were reportedly to play crucial roles in papillary thyroid carcinoma (PTC) tumorigenesis and development. Therefore, the discovery of miRNAs may provide a new and powerful tool for diagnosis and treatment of PTC.

Purpose

The aim of this study was to investigate the biological function and underlying mechanism of miR-622 in PTC.

Materials and methods

The expression levels of miR-622 in PTC patient tissues and cell lines were determined by quantitative RT-PCR (qRT-PCR). The biological function including cell proliferation, colony formation, migration and invasion, as well as underling mechanism of miR-622 in PTC, were also evaluated by a series of in vitro and in vivo experiments.

Results

miR-622 expression level was significantly downregulated in PTC tissues and cell lines. Decreased miR-622 expression was associated with advanced clinical stage and lymph node metastasis (P<0.01). The overexpression of miR-622 in TPC-1 cells inhibited cell proliferation, migration and invasion in vitro, as well as suppress tumor growth in vivo. Moreover, we also demonstrated that miR-622 specifically targeted the 3'-UTR regions of vascular endothelial growth factor A (VEGFA) and inhibited its expression both mRNA level and protein levels. Overexpression of VEGFA reversed miR-622-mediated inhibition effect on cell proliferation, migration and invasion in thyroid cancer cells. More importantly, VEGFA expression was significantly increased and inversely correlated with the levels of miR-622 in PTC tissues.

Conclusion

These results show that miR-622 acts as a tumor suppressor in thyroid cancer, at least in part, via targeting VEGFA, and suggest that miR-622 may serves as a potential target for treatment of thyroid cancer patients.

The Oncogenic Relevance of miR-17-92 Cluster and Its Paralogous miR-106b-25 and miR-106a-363 Clusters in Brain Tumors

The fundamental function of ribonucleic acids is to transfer genetic information from DNA to protein during translation process, however, this is not the only way connecting active RNA sequences with essential biological processes. Up until now, many RNA subclasses of different size, structure, and biological function were identified. Among them, there are non-coding single-stranded microRNAs (miRNAs). This subclass comprises RNAs of 19–25 nucleotides in length that modulate the activity of well-defined coding RNAs and play a crucial role in many physiological and pathological processes. miRNA genes are located both in exons, introns, and also within non-translated regions. Several miRNAs that are transcribed from the adjacent miRNA genes are called cluster. One of the largest ones is miR-17-92 cluster known as OncomiR-1 due to its strong link to oncogenesis. Six miRNAs from the OncomiR-1 have been shown to play important roles in various physiological cellular processes but also through inhibition of cell death in many cancer-relevant processes. Due to the origin and similarity of the sequence, miR-17-92 cluster and paralogs, miR-106b-25 and miR-106a-363 clusters were defined. Here we discuss the oncogenic function of those miRNA subgroups found in many types of cancers, including brain tumors.

MiR-22 down-regulates the proto-oncogene ATP citrate lyase to inhibit the growth and metastasis of breast cancer

Breast cancer, the most common malignancy in women worldwide, places a heavy economic burden and mental stress on families and society. Previous research showed that abnormal expression of miRNAs was closely related to the occurrence, metastasis, and angiogenesis of breast cancer. And in this study, the abnormal expression of miR-22 was detected by RT-PCR in the paired breast cancer tissues and adjacent non-tumor tissues. CCK-8 and wound healing assays were performed to evaluate the effects of the proto-oncogene ATP citrate lyase (ACLY) on the growth and metastasis of breast cancer MCF-7 cells. The results showed that miR-22 inhibited the growth and metastasis of MCF-7 cells by down-regulating the expression of ACLY. In conclusion, this study elucidated the roles of miR-22 in regulation of breast cancer differentiation and migration, which provides a target for early diagnose and therapy of breast cancer.

MiR-362-5p as a novel prognostic predictor of cytogenetically normal acute myeloid leukemia

Background

MicroRNAs are of special interest in cancer research and hold significant promise as diagnostic and prognostic biomarkers for malignant disease. MiR-362-5p have been found to exert both oncogenic and tumor suppressive effects depending highly on the cellular context. The aim of this study was to determine whether the expression of miR-362-5p can be served as a prognostic factor for patients with cytogentically normal acute myeloid leukemia (CN-AML).

Methods

We enrolled 224 patients with CN-AML and measured the expression of miR-362-5p by quantitative real time PCR analysis. We classified patients into high and low expression based on the median value. The Cox regression analyses were carried out to assess the prognostic significance of miR-362-5p expression in the context of the well-established predictors. Additionally, microRNA expression profiling were conducted to identify the biological insights between high and low group.

Results

High expressers had older age. High expressers obtained shorter overall survival in the univariate analysis. The independent prognostic value of miR-362-5p remained in the context of the well-established clinical and cytogenetic predictors. Moreover, the prognostic value of miR-362-5p was also validated in an independent cohort of CN-AML. Notably, numerous oncomiRs were also high expressed in high miR-362-5p group.

Conclusion

High miR-362-5p expression was associated with poorer overall survival implicating the oncogenic function in AML development.

Expression of miR-634 in gastric carcinoma and its effects on proliferation, migration, and invasion of gastric cancer cells

This study aims to observe the expression of microRNA (miR)‐634 in different gastric cancer cell lines and tissues, and to study the effects of miR‐634 on the proliferation, migration, and invasion of the gastric cancer cells. The miR‐634 mimics and miR‐634 inhibitors were transfected by lentivirus into human gastric cancer SGC‐7901 and MGC‐803 cells, and the miR‐634 cells without transfection were used as the control group (NC group). The expression of miR‐634 in the transfected cells was detected by qRT‐PCR. Cell viability was measured by the CCK8 assay. The migration and invasion ability of the cells were detected by scratch assays and Transwell^® chamber assays, respectively, and the luciferase assay verified the binding of miR‐634 to the target gene JAG1. The expression level of miR‐634 in gastric cancer tissues and cell lines was significantly lower than that in normal adjacent tissues and control cells. The survival of cells was significantly decreased, and number of cells migrating and invading was decreased in the miR‐634 mimics group. However, in the miR‐634 inhibitor group, the opposite results were observed. Over‐expression of miR‐634 inhibited the proliferation, migration, and invasion of gastric cancer cell lines, and the miR‐634 target gene was JAG1.

MicroRNA-150 inhibitors enhance cell apoptosis of melanoma by targeting PDCD4

Malignant melanoma is a tumor with a high mortality rate. Previous studies have demonstrated that the oncogenesis of melanoma is associated with microRNA (miR)-150. However, the role of miR-150 in melanoma and its regulatory mechanisms are still unclear. In the present study, melanoma cancer tissues and adjacent normal tissues were obtained from 20 melanoma patients. The expression level of miR-150 in melanoma tissue and cell lines was detected by reverse transcription-quantitative polymerase chain reaction. miR-150 inhibitors/negative control were transfected into melanoma A375 cells in order to investigate the effects of miR-150 on cell proliferation, apoptosis, cell cycle migration and invasion using a Cell Counting Kit-8, colony formation, Hoechst 33528, flow cytometry, and Transwell assays. The association between miR-150 and programmed cell death protein-4 (PDCD4) was detected by a dual luciferase reporter assay. The functional role of PDCD4 in miR-150-affected melanoma cells was confirmed by small interfering (si)RNA knockdown. Results demonstrated that miR-150 was significantly upregulated and mRNA and protein expressions of PDCD4 were decreased in melanoma cancer tissues as compared with adjacent normal tissues. The level of PDCD4 was inversely associated with the level of miR-150. Transfection of miR-150 inhibitors suppressed cell proliferation, migration, and invasion, while the apoptosis of cells was promoted and G2/M cell arrest was induced. MiR-150 inhibitors enhanced the expression of caspase-8 and p21. The PDCD4 was identified as a direct target gene of miR-150. The effects of miR-150 inhibitors on apoptosis and apoptosis-associated proteins, including caspase-8 and p21, of A375 cells, were reversed following transfection of siRNA-PDCD4. Therefore, miR-150 inhibitors enhance cell apoptosis via upregulation of PDCD4-mediated activation of caspase-8 and p21. These findings demonstrate the potential for a promising therapeutic strategy in the management of melanoma.

microRNA-9 functions as a tumor suppressor in colorectal cancer by targeting CXCR4

MicroRNAs (miRs) dysregulation has been proven to play a crucial role in the initiation and progression of colorectal cancer (CRC). miR-9 functions as a tumor suppressor in many cancer types, including CRC. However, the precise role of miR-9 and the underlying molecular mechanisms that miR-9 involves in CRC progression remain largely unknown. In this study, it was reported that miR-9 had lower expression in CRC tissue samples than in those matched adjacent non-tumor tissues. Deregulated miR-9 expression was inverse correlated with the TNM stage, lymph node metastasis, and prognosis of CRC patients. Ectopic miR-9 expression suppressed CRC cell proliferation, migration, and invasion. Dual-Luciferase Reporter Assay confirmed that C-X-C Motif Chemokine Receptor 4 (CXCR4) was a direct miR-9 target, and the effects of miR-9 were mimicked through CXCR4 depletion in vitro. CXCR4 rescue experiments further verified that CXCR4 is a functional target of miR-9. Animal xenograft assays also provided evidence that miR-9 functions as a tumor suppressor via targeting CXCR4 in vivo. Mechanistically, miR-9 overexpression or CXCR4 knockdown influenced cell proliferation and epithelial-mesenchymal transition (EMT). Results suggest that miR-9 acts as a tumor suppressor in CRC progression by regulating CXCR4.

miR-3928v is induced by HBx via NF-κB/EGR1 and contributes to hepatocellular carcinoma malignancy by down-regulating VDAC3

BACKGROUND

Hepatitis B virus (HBV) plays a critical role in the tumorigenic behavior of human hepatocellular carcinoma (HCC). MicroRNAs (miRNAs) have been reported to participate in HCC development via the regulation of their target genes. However, HBV-modulated miRNAs involved in tumorigenesis remain to be identified. Here, we found that a novel highly expressed miRNA, TLRC-m0008_3p (miR-3928v), may be an important factor that promotes the malignancy of HBV-related HCC.

METHODS

Solexa sequencing was applied to profile miRNAs, and RT-qPCR was used to identify and quantitate miRNAs. We studied miR-3928v function in HCC cell lines by MTT, colony formation, migration/invasion, and vascular mimicry (VM) assays in vitro and by a xenograft tumor model in vivo. Finally, we predicted and verified the target gene of miR-3928v by a reporter assay, studied the function of this target gene, and cloned the promoter of miR-3928v and the transcription factor for use in dual-luciferase reporter assays and EMSAs.

RESULTS

A variant of miR-3928 (miR-3928v) was identified and found to be highly expressed in HBV (+) HCC tissues. Voltage-dependent anion channel 3 (VDAC3) was validated as a target of miR-3928v and found to mediate the effects of miR-3928v in promoting HCC growth and migration/invasion. Furthermore, HBx protein increased early growth response 1 (EGR1) expression and facilitated its translocation into the nucleus to enhance miR-3928v promoter activity in an NF-κB signaling-dependent manner.

CONCLUSIONS

miR-3928v is induced by HBx through the NF-κB/EGR1 signaling pathway and down-regulates the tumor suppressor gene VDAC3 to accelerate the progression of HCC.

microRNA-874 suppresses tumor proliferation and metastasis in hepatocellular carcinoma by targeting the DOR/EGFR/ERK pathway

The δ opioid receptor (DOR) is involved in the regulation of malignant transformation and tumor progression of hepatocellular carcinoma (HCC). However, regulation of the DOR in HCC remains poorly defined. We found that miR-874 was identified as a negative regulator of the DOR, which is a direct and functional target of miR-874 via its 3' untranslated region (UTR). Moreover, miR-874 was downregulated in HCC and its expression was inversely correlated with DOR expression. Downregulation of miR-874 was also associated with larger tumor size, more vascular invasion, a poor TNM stage, poor tumor differentiation, and inferior patient outcomes. Functionally, overexpression of miR-874 in the HCC cell line SK-hep-1 inhibited cell growth, migration, in vitro invasion, and in vivo tumorigenicity. Furthermore, miR-874 overexpression suppressed the DOR, resulting in a downregulated epidermal growth factor receptor (EGFR) and extracellular signal-regulated kinase (ERK) phosphorylation. The EGFR activator-epidermal growth factor (EGF)-can rescue the proliferation and migration suppression induced by miR-874 overexpression, and the rescue effects of the EGF were blocked by an ERK inhibitor. Our study results suggest that miRNA-874 is a negative regulator of the DOR that can suppress tumor proliferation and metastasis in HCC by targeting the DOR/EGFR/ERK pathway, which may be a potential target for HCC treatment.

Apigenin sensitizes hepatocellular carcinoma cells to doxorubic through regulating miR-520b/ATG7 axis

Chemo-resistance is a serious obstacle for successful treatment of cancer. Apigenin, a dietary flavonoid, has been reported as an anticancer drug in various malignant cancers. This study aimed to investigate the potential chemo-sensitization effect of apigenin in doxorubicin-resistant hepatocellular carcinoma cell line BEL-7402/ADM. We observed that apigenin significantly enhanced doxorubicin sensitivity, induced miR-520b expression and inhibited ATG7-dependent autophagy in BEL-7402/ADM cells. In addition, we also showed that miR-520b mimics increased doxorubicin sensitivity and inhibited ATG7-dependent autophagy. Meanwhile, we indicated that ATG7 was a potential target of miR-520b. Furthermore, APG inhibited the growth of hepatocellar carcinoma xenografts in nude mice by up-regulating miR-520b and inhibiting ATG7. Our finding provides evidence that apigenin sensitizes BEL-7402/ADM cells to doxorubicin through miR-520b/ATG7 pathway, which furtherly supports apigenin as a potential chemo-sensitizer for hepatocellular carcinoma.

GSE1 predicts poor survival outcome in gastric cancer patients by SLC7A5 enhancement of tumor growth and metastasis

Gastric cancer remains a malignancy with poor survival outcome. We herein report that GSE1, a proline-rich protein, possesses a role in the progression of human gastric cancer. The expression of GSE1 was observed to be much higher in human gastric cancer tissues compared with normal gastric tissues, and GSE1 expression correlated positively with lymph node metastasis, histological grade, depth of invasion, and clinical stage in gastric cancer patients. Moreover, GSE1 expression was also associated with decreased post-operative relapse-free survival and overall survival in the cohort. The forced expression of GSE1 in gastric cancer cell lines resulted in increased cell proliferation, increased colony formation, enhanced cell migration, and invasion. Furthermore, forced expression of GSE1 also increased tumor size and enhanced lung metastasis in xenograft models. The depletion of endogenous GSE1 with shRNAs decreased the oncogenicity and invasiveness of gastric cancer cells both in vitro and in vivo In addition, GSE1 was determined to be a direct target of miR-200b and miR-200c. Furthermore, GSE1 positively regulated the downstream gene SLC7A5 (also known as LAT-1), which was scanned and verified from mRNA sequencing. GSE1 therefore possesses an oncogenic role in human gastric cancer, and targeted therapeutic approaches to inhibit GSE1 function in gastric cancer warrant further consideration.

miR-433 accelerates acquired chemoresistance of gallbladder cancer cells by targeting cyclin M

Resistance to chemotherapy is associated with dismal prognosis in patients with gallbladder cancer. Cyclin-dependent kinase 10 (CDK10) influences the chemosensitivity of gallbladder cancer cells, and cyclin M is the activating factor and binding partner of CDK10. To determine the effect of CDK10 or cyclin M overexpression on chemosensitivity, gemcitabine-resistant (GR) subclones were established from CDK10 or cyclin M stable transfectants. Stable overexpression of CDK10 increased the sensitivity to gemcitabine in non-resistant cells and did not further increase the sensitivity to gemcitabine in the GR subclones. GR subclones exhibited a significantly decreased expression of cyclin M while maintaining the expression levels of CDK10, compared with the non-resistant cells. MicroRNA (miR)-433 was identified as a candidate factor involved in the mechanism of the downregulation of M cyclin in GR subclones. Luciferase assays confirmed the interaction between miR-433 and the 3' untranslated region (3'UTR) of cyclin M. Additionally, ectopic expression of miR-433 significantly decreased the expression of cyclin M. Finally, increased expression of circulating miR-433 was associated with poor outcome of chemotherapy. The results of the present study suggest that miR-433 is a potential biomarker for evaluating chemosensitivity in gallbladder cancer.

Development of Novel Therapeutic Agents by Inhibition of Oncogenic MicroRNAs

MicroRNAs (miRs, miRNAs) are regulatory small noncoding RNAs, with their roles already confirmed to be important for post-transcriptional regulation of gene expression affecting cell physiology and disease development. Upregulation of a cancer-causing miRNA, known as oncogenic miRNA, has been found in many types of cancers and, therefore, represents a potential new class of targets for therapeutic inhibition. Several strategies have been developed in recent years to inhibit oncogenic miRNAs. Among them is a direct approach that targets mature oncogenic miRNA with an antisense sequence known as antimiR, which could be an oligonucleotide or miRNA sponge. In contrast, an indirect approach is to block the biogenesis of miRNA by genome editing using the CRISPR/Cas9 system or a small molecule inhibitor. The development of these inhibitors is straightforward but involves significant scientific and therapeutic challenges that need to be resolved. In this review, we summarize recent relevant studies on the development of miRNA inhibitors against cancer.

Prostate cancer small non-coding RNA transcriptome in Arabs

BACKGROUND

Prostate cancer (PCa) is a complex disorder resulting from the combined effects of multiple environmental and genetic factors. Small non-coding RNAs (sRNAs), particularly microRNAs (miRNAs), regulate several cellular processes and have an important role in many human malignancies including PCa. We assessed the sRNA profiles associated with PCa in Arabs, a population that has rarely been studied.

METHODS

We used next generation sequencing technology to obtain the entire sRNA transcriptome of primary prostate tumor formalin-fixed paraffin-embedded tissues, and their paired non-tumor tissues, collected from Bedouin patients (Qatari and Saudi). The miRNA and the target gene expression were evaluated by real-time quantitative PCR. miRNA KEGG pathway and miRNA target genes were subsequently analyzed by starBase and TargetScan software.

RESULTS

Different expression patterns of several sRNA and miRNA editing were revealed between PCa tumor and their paired non-tumor tissues. Our study identified four miRNAs that are strongly associated with prostate cancer, which have not been reported previously. Differentially expressed miRNAs significantly affect various biological pathways, such as cell cycle, endocytosis, adherence junction and pathways involved in cancer. Prediction of potential targets for the identified miRNAs indicates the overexpression of KRAS, BCL2 and down-regulation of PTEN in PCa tumor tissues.

CONCLUSION

These miRNAs, newly associated with prostate cancer, may represent not only markers for the increased risk of PCa in Arabs, but may also reflect the clinical and pathological diversity as well as the ethno-specific heterogeneity of prostate cancer.

MicroRNA-429 sensitizes pancreatic cancer cells to gemcitabine through regulation of PDCD4

One of the features for pancreatic cancer is that it is often resistant to chemotherapy treatment, which is one of the major hindrances in the treatment of this malignancy. Previous studies indicated that the microRNAs (miRNAs) could mediate resistance of tumor cells to chemotherapy drug in the cancer progression. In the present study, we are aimed to examine whether microRNA-429 was involved in mediating the chemo-resistance of pancreatic cancer cells to gemcitabine. Firstly, a gemcitabine-resistant pancreatic cancer cell line (SW1990/GZ) derived from cell line (SW1990) was constructed and found to possess a decreased expression of miR-429 when it is compared to the original cell line. Ectopic expression of miR-429 in SW1990/GZ increased the cellular sensibility to the treatment of gemcitabine, which is coincided with increased expression of PDCD4. As a tumor suppressor, we found that PDCD4 knockdown in SW1990/GZ cells increased its own chemo-resistance to GZ, which indicates PDCD4 also play a regulative role on the GZ-resistance in the pancreatic cancer. To further confirm the function of miR-429 and PDCD4 in gemcitabine-resistant pancreatic cancer, a xenograft nude mouse model was utilized to examine whether miR-429 can restore treatment response of gemcitabine in gemcitabine-resistant xenografts, while protein levels of PDCD4 were up-regulated. Together with those results, these findings collectively provided that miR-429 could enhancer GZ sensitivity via regulation of PDCD4 expression in pancreatic cancer cells, which may offer a novel therapeutic target for the chemotherapy resistance in pancreatic cancer.

MicroRNA-655-3p regulates Echinacea purpurea mediated activation of ABCG2

1. The aim of this study was to investigate the regulatory effect of Echinacea purpurea (EP) on efflux transporters ABCB1 and ABCG2 and to identify specific microRNAs contributing to their post-transcriptional regulation. 2. ABCB1 and ABCG2 levels were assessed in human hepatoblastoma HepG2 cells treated with 50 µg/mL methanolic extract of commercial EP capsules for different durations. The microRNA expression profile of HepG2 cells after EP treatment was evaluated and in silico target prediction was subsequently conducted to identify specific microRNAs with binding sites in the 3'-UTR of ABCB1 and ABCG2. Luciferase reporter gene assays and site-directed mutagenesis were used to confirm the binding site of identified microRNA within the 3'-UTR of the target gene. 3. EP increased ABCB1 (10-fold ± 3.4, p < 0.001) and ABCG2 (2.7-fold ± 0.5, p < 0.01) mRNA levels after 12 h exposure. Twenty-four microRNAs showed significant expression differences at all durations of exposure to EP. MiR-655-3p showed a 6.79-fold decrease in expression after 12 h exposure compared to 0 h, was predicted in silico to bind ABCG2 3'-UTR and showed a significant negative correlation (p = 0.01) to ABCG2 expression level. The binding of miR-655-3p to ABCG2 3'-UTR was confirmed by reporter gene assays (reduction of reporter gene activity to 60%; p = 0.0001). 4. These results suggest that EP regulates ABCG2 expression via downregulation of miR-655-3p in the liver cells. Thus, miR-655-3p downregulation could be applied to predict EP mediated drug interactions.

MicroRNA‑760 inhibits cell proliferation and invasion of colorectal cancer by targeting the SP1‑mediated PTEN/AKT signalling pathway

Colorectal cancer (CRC), one of the most commonly diagnosed types of cancer worldwide, is the third most prevalent and fourth most frequent cause of cancer‑related mortality. Dysregulated microRNAs (miRNAs) have potential regulatory roles in the development and progression of various cancer types. Therefore, the investigation of the miRNAs involved in CRC formation and progression may lead to the development of highly effective therapeutic strategies for CRC. In the present study, miRNA‑760 (miR‑760) was frequently downregulated in CRC tissues and cell lines. The low levels of miR‑760 expression were significantly correlated with the tumor size, lymph node metastasis and TNM stage of CRC. Functional assays revealed that restoring miR‑760 expression inhibited CRC cell proliferation and invasion in vitro. The results of bioinformatics analysis, luciferase reporter assay, reverse transcription‑quantitative polymerase chain reaction and western blot analysis suggested that specificity protein 1 (SP1) is a direct target of miR‑760 in CRC. The high expression of SP1 in CRC tissues was inversely correlated with the expression of miR‑760. Rescue experiments demonstrated that enforced SP1 expression rescued the tumor‑suppressing effects of miR‑760 on CRC cell proliferation and invasion. In addition, miR‑760 overexpression is involved in the regulation of the PTEN/AKT signalling pathway. Collectively, the present data demonstrated that miR‑760 directly targets SP1 to inactivate the PTEN/AKT signalling pathway, thus implicating miR‑760 in the regulation of CRC cell proliferation and invasion. Therefore, miR‑760 may be a novel biomarker and therapeutic target for CRC.

Prognostic evaluation of microRNA-210 in various carcinomas: Evidence from 19 studies

BACKGROUND

We performed this meta-analysis to provide a comprehensive evaluation of the role of MicroRNA-210 (miR-210) expression on the overall survival (OS) rate of cancers.

METHODS

We searched for relevant available literatures on miR-210 and cancer until November 1st, 2016 on the databases PubMed, EMBASE, Cochrane Library, and Science Direct database. We calculated the pooled hazard ratio (HR) with 95% confidence intervals (CIs) for OS, which compared the high and low expression levels of miR-210 in patients of the available studies. Subgroup analysis was performed to evaluate the specific role of miR-210 in ethnicity and the type of cancers. Publication bias was evaluated using Begg funnel plots and Egger regression test.

RESULTS

Overall, 19 studies were involved in this meta-analysis. The result indicated that upregulated miR-210 might be associated with poor OS outcome in various carcinomas, with the pooled HR of 1.80 (95% CI: 1.29-2.51). When stratified by disease, significant results were detected in breast cancer (HR = 2.67, 95% CI: 1.24-5.76) and glioma (HR = 2.42, 95% CI: 1.32-4.43). Besides, in the subgroup analysis by ethnicity, significant results were detected only in Asian populations (HR = 2.14, 95% CI: 1.37-3.34).

CONCLUSION

The present meta-analysis suggests that high expressed miR-210 is significantly associated with OS in cancer patients, which has the potential to be a prognostic marker in cancers.

MicroRNAs as Biomarkers in Thyroid Carcinoma

Optimal management of patients with thyroid cancer requires the use of sensitive and specific biomarkers. For early diagnosis and effective follow-up, the currently available cytological and serum biomarkers, thyroglobulin and calcitonin, present severe limitations. Research on microRNA expression in thyroid tumors is providing new insights for the development of novel biomarkers that can be used to diagnose thyroid cancer and optimize its management. In this review, we will examine some of the methods commonly used to detect and quantify microRNA in biospecimens from patients with thyroid tumor, as well as the potential applications of these techniques for developing microRNA-based biomarkers for the diagnosis and prognostic evaluation of thyroid cancers.

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

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

MicroRNAs and Cancer: A Long Story for Short RNAs

More than six decades ago Watson and Crick published the chemical structure of DNA. This discovery revolutionized our approach to medical science and opened new perspectives for the diagnosis and treatment of many diseases including cancer. Since then, progress in molecular biology, together with the rapid advance of technologies, allowed to clone hundreds of protein-coding genes that were found mutated in all types of cancer. Normal and aberrant gene functions, interactions, and mechanisms of mutations were studied to identify the intricate network of pathways leading to cancer. With the acknowledgment of the genetic nature of cancer, new diagnostic, prognostic, and therapeutic strategies have been attempted and developed, but very few have found their way in the clinical field. In an effort to identify new translational targets, another great discovery has changed our way to look at genes and their functions. MicroRNAs have been the first noncoding genes involved in cancer. This review is a brief chronological history of microRNAs and cancer. Through the work of few of the greatest scientists of our times, this chapter describes the discovery of microRNAs from C. elegans to their debut in cancer and in the medical field, the concurrent development of technologies, and their future translational applications. The purpose was to share the exciting path that lead to one of the most important discoveries in cancer genetics in the past 20 years.

rhPDGF-BB combined with ADSCs in the treatment of Achilles tendinitis via miR-363/PI3 K/Akt pathway

To investigate the mechanism of recombinant human platelet-derived growth factor-BB (rhPDGF-BB) and human adipose-derived stem cells (hADSCs) in the treatment of Achilles tendinitis. Biomechanical indices of stiffness, stress, and maximum load-to-failure were detected by biomechanical test. mRNA and protein levels of miR-363, p-PI3K/AKT, tendon-related genes Collagen I, Scleraxis (Scx), and Tenascin C (TNC) were measured by qRT-PCR and western blot. The proliferation of hADSCs was accessed by MTT assay. Biomechanical indices of stiffness, stress, and maximum load-to-failure, and mRNA and protein levels of tendon-related genes could be improved by rhPDGF-BB or hADSCs alone, and could be further improved by rhPDGF-BB + hADSCs. rhPDGF-BB and hADSCs downregulated the expression of miR-363 and upregulated the levels of p-PI3K/Akt, and rhPDGF-BB + hADSCs further strengthened these effects. In addition, rhPDGF-BB promoted the proliferation of hADSCs in vitro and upregulated the expression of tendon-related genes. miR-363 mimic downregulated the levels of p-PI3K/Akt, miR-363 inhibitor upregulated the levels of p-PI3K/Akt, and miR-363 mimic and PI3K/Akt pathway inhibitor LY294002 reversed the positive effect of rhPDGF-BB on the proliferation of hADSCs, which suggested that rhPDGF-BB promoted the proliferation of hADSCs via miR-363/PI3K/Akt pathway. Biomechanical indices and tendon-related genes could be improved by rhPDGF-BB and hADSCs. Moreover, rhPDGF-BB promoted the proliferation of hADSCs via miR-363/PI3K/Akt pathway, indicating that rhPDGF-BB combined with ADSCs could treat Achilles tendinitis via miR-363/PI3K/Akt pathway.

MicroRNA-613 is downregulated in HCMV-positive glioblastoma and inhibits tumour progression by targeting arginase-2

Glioblastoma is the most common and malignant tumour that occurs primarily in nervous system and has a high morbidity. Research on glioblastoma has recently focused on human cytomegalovirus, belonging to the beta subfamily of Herpesviridae that plays crucial roles in cancer development and progression. This study aimed to investigate the role of human cytomegalovirus–associated microRNA-613 in glioblastoma. In this study, we demonstrate that microRNA-613 expression was frequently reduced in human cytomegalovirus–positive glioblastoma specimens/cells compared with human cytomegalovirus–negative glioblastoma tissue/cells, and a significant correlation was observed between the reduction in microRNA-613 expression and the presence of unfavourable variables, including tumour size (p = 0.0118), World Health Organization stage (p = 0.0169), the overall survival (p = 0.0107) and disease-free (p = 0.0159) survival of patients. Overexpression of microRNA-613 in the glioblastoma cell lines U87 and U251 retarded cell growth and induced cell apoptosis. Upregulation of microRNA-613 inhibited glioblastoma cell clone formation, invasion and migration. Furthermore, we demonstrated that arginase-2 was directly regulated by microRNA-613 and played an essential role in mediating the biological effects of microRNA-613 in glioblastoma. Re-expression of arginase-2 markedly reversed the inhibitory properties of microRNA-613 in glioblastoma cells. Taken together, our data provide compelling evidence that human cytomegalovirus reduced the level of microRNA-613 which functions as an anti-onco-miRNA in glioblastoma, primarily by downregulating the expression of arginase-2.

MicroRNA-299-3p suppresses proliferation and invasion by targeting VEGFA in human colon carcinoma

Accumulating evidences have shown that microRNAs (miRNAs) are vital regulators and possess huge capabilities in post-transcriptional control. Although a large number of miRNAs have been identified to be dysregulated in human cancers especially in colon cancer, our understandings of the function of most miRNAs are still largely limited. In this study, we have demonstrated that miR-299-3p plays a critical role in suppressing colon carcinoma progression by targeting Vascular Endothelial Growth Factor A (VEGFA). We observed that miR-299-3p was down-regulated in colon carcinoma tissues and colon cancer cell lines. The level of miR-299-3p was significantly negatively correlated with that of VEGFA mRNA level in colon carcinoma. More importantly, the low level of miR-299-3p predicted poor prognosis of colon cancer patients. Functionally, overexpression of miR-299-3p inhibited the proliferation and invasion of colon carcinoma cells and suppressed the growth of colon cancer xenografts in nude mice. Luciferase reporter assays showed that miR-299-3p could target VEGFA 3' UTR. In addition, up-regulation of miR-299-3p decreased VEGFA expression both in vitro and in vivo, showing that miR-299-3p plays a suppressive effect on VEGFA via post-transcriptional control. However, ectopical expression of VEGFA could abrogate this effect and also abolish miR-299-3p-induced inhibition of cell proliferation and invasion. Taken together, our study provides evidences showing that miR-299-3p functions as a suppressor in colon cancer by targeting VEGFA, suggesting that miR-299-3p might serve as a novel target for colon cancer therapy.

Identification of novel diagnostic and prognostic miRNA signatures in endometrial cancer

With the goal of identifying diagnostic and prognostic biomarkers in endometrial cancer, miRNA-profiling was carried out with formalin-fixed paraffin embedded (FFPE) tissue samples from 49 endometrial cancer patients. Results using an 84-cancer specific miRNA panel identified the upregulation of miR-141-3p and miR-96-5p along with a downregulation of miR-26, miR-126-3p, miR-23b, miR-195-5p, miR-374a and let-7 family of miRNAs in endometrial cancer. We validated the dysregulated expression of the identified miRNAs in a panel of endometrial cancer cell-lines. Immunohistochemical analysis of the tissue micro array derived from these patients established the functional correlation between the decreased expression of tumor suppressive miRNAs and their target oncogenes: ERBB2, EGFR, EPHA2, BAX, GNA12, GNA13, and JUN. Comparative analysis of the samples from the patients with extended progression-free survival (PFS) ( > 21 months) versus the patients with the PFS of < 21 months indicated increased expression of tumor suppressive miR-142-3p, miR-142-5p, and miR-15a-5p in samples from extended PFS patients. In addition to defining a specific set of miRNAs and their target genes as potential diagnostic biomarkers, our studies have identified tumor suppressive miR-142 cluster and miR-15a as predictors of favorable prognosis for therapy response in endometrial cancer.

Apigenin sensitizes BEL-7402/ADM cells to doxorubicin through inhibiting miR-101/Nrf2 pathway

Chemo-resistance is one of the main obstacle in hepatocellular carcinoma therapy. Apigenin as a natural bioflavonoid has been exhibited anti-cancer properties in various malignant cancers. The aim of this study is to evaluate the potential chemo-sensitization effect of apigenin in doxorubicin-resistant hepatocellular carcinoma cell line BEL-7402/ADM and to investigate its possible mechanism. We found that apigenin significantly reversed doxorubicin sensitivity and induced caspase-dependent apoptosis in BEL-7402/ADM cells. Furthermore, apigenin induced miR-101 expression, and overexpression of miR-101 mimicked the doxorubicin-sensitizing effect of apigenin. Importantly, we showed that miR-101 was able to target the 3'-UTR of Nrf2. The results suggested that apigenin sensitizes BEL-7402/ADM cells to doxorubicin through miR-101/Nrf2 pathway, which furtherly supports apigenin as a potential chemo-sensitizer for hepatocellular carcinoma.