MicroRNA as a novel drug target for cancer therapy

The Role of miRNAs in Childhood Acute Lymphoblastic Leukemia Relapse and the Associated Molecular Mechanisms

Acute lymphoblastic leukemia (ALL) is the most common cancer in children worldwide. Although ALL patients' overall survival rates in wealthy countries currently surpass 80%, 15-20% of patients still experience relapse. The underlying mechanisms of relapse are still not fully understood, and little progress has been made in treating refractory or relapsed disease. Disease relapse and treatment failure are common causes of leukemia-related death. In ALL relapse, several gene signatures have been identified, but it is also important to study miRNAs involved in ALL relapse in an effort to avoid relapse and to achieve better survival rates since miRNAs regulate target genes that participate in signaling pathways involved in relapse, such as those related to drug resistance, survival signals, and antiapoptotic mechanisms. Several miRNAs, such as miR-24, miR-27a, miR-99/100, miR-124, miR-1225b, miR-128b, miR-142-3p, miR-155 and miR-335-3p, are valuable biomarkers for prognosis and treatment response in ALL patients. Thus, this review aimed to analyze the primary miRNAs involved in pediatric ALL relapse and explore the underlying molecular mechanisms in an effort to identify miRNAs that may be potential candidates for anti-ALL therapy soon.

Long-term continuous monitoring of microRNA in living cells using modified gold nanoprobe

Long-term and continuous monitoring of the microRNA (miRNA) expression in living cells is essential in biomedical research, but it is currently limited by fast consumption and easy digestion of probes in the intracellular environment. Herein, we report polydopamine-modified gold nanoparticles (AuNPs@PDA) as protective and efficient nanocarriers for DNA hairpin probes (hpDNA), achieving long-term monitoring (48 h) of the miRNA (let-7a) levels in living cells after drug treatments. This method enabled excellent sensitivity and high selectivity toward let-7a with a limit of detection of 0.51 nM (n = 3) and a linear range from 1 to 100 nM. More importantly, AuNPs@PDA can not only efficiently improve the loading of hpDNA on each nanoparticle, but also effectively protect hpDNA from hydrolysis in the cell microenvironment, finally realizing the continuous monitoring of let-7a in living cells for 48 h. This simple method would be of great significance for drug screening and precision medicine.

The role of vesicular overexpressed in cancer pro-survival protein 1 in hepatocellular carcinoma proliferation

BACKGROUND

Recently, hepatocellular carcinoma (HCC) has been ranked as the second leading cause of cancer-associated death. However, the underlying molecular mechanisms of HCC progression remain unclear. Vesicular overexpressed in cancer pro-survival protein 1 (VOPP1) could be upregulated in a quantity of human cancers, including squamous cell carcinoma (SCC), gastric cancer, and glioblastoma. However, the precise functional mechanism of VOPP1 in HCC remains poorly understood. The present study aimed to investigate the role of VOPP1 in HCC proliferation.

METHODS

Immunohistochemistry (IHC), Western blot and Reverse-transcription polymerase chain reaction (RT-PCR) were used to analyze the protein and mRNA expressions of VOPP1, mitogen-activated protein kinase (MAPK) 14, ribosomal protein S6 kinase β1 (RPS6KB1), cylindromatosis (CYLD) and Twist family bHLH transcription factor 1 (TWIST1). The cell proliferation and apoptosis were tested using Celigo cell imaging analyzer and annexin V-APC apoptosis detection kit respectively. Colony formation and tumor xenograft assays were performed to understand their roles in tumorigenicity.

RESULTS

The expression of VOPP1 in HCC samples was higher than that in adjacent noncancerous tissues by immunohistochemistry. In addition, the down-regulation of VOPP1 using shRNA inhibited cell proliferation and tumour growth, and induced cell apoptosis in vitro and in vivo. Furthermore, VOPP1 silencing increased the expression of MAPK14 and RPS6KB1, indicating that the MAPK and mTOR signalling pathways might be involved in VOPP1-mediated cancer cell proliferation.

CONCLUSION

The present data indicate that VOPP1 may play an important role in the progression of HCC by targeting the MAPK and mTOR signalling pathways, and that VOPP1 may potentially be a candidate as a novel molecular target for HCC therapy.

Nanoparticles-based drug delivery and gene therapy for breast cancer: Recent advancements and future challenges

Breast cancer (BC) is amongst the most lethal cancer among females and conventional treatment methods like surgery, radiotherapy and chemotherapy are not effective enough as expected and suffer concerns of low bioavailability, low cellular uptake, emerging resistance, and adverse toxicities. Gene therapy using free nucleic acids has potential to deal with key candidate genes of BC, but their effect is retarded due to poor cell uptake and instability in circulation. The rapidly evolving field of nanomedicine aiming targeted drug/gene delivery curtailing BC promises to overcome the limitations of conventional therapies. Nanoparticles can be game changer for BC gene therapy as they can be effective carrier of specific drug/gene by improving the circulation time, enhancing bioavailability, reducing the immune system based recognition chances, and delivering the gene regulator accurately. Herein, we discuss the mechanism of nanoparticles targeted drug delivery, recent advancement of therapeutic strategies of nanoparticles based carriers for small interfering RNA, and microRNA, and gene augmentation therapies in BC. We also discuss the future prospect and challenges of nanoparticle-based therapies for BC.

MicroRNA-301b promotes the proliferation and invasion of glioma cells through enhancing activation of Wnt/β-catenin signaling via targeting Glypican-5

Accumulating evidence has suggested that Glypican-5 (GPC5) is a tumor suppressor gene in many types of cancers. However, whether GPC5 is involved in glioma remains unknown. This study was designed to explore the expression, biological function and regulatory mechanism of GPC5 in glioma. Our results demonstrated that GPC5 expression was significantly decreased in multiple glioma cell lines. Gain-of-function experiments showed that the ectopic expression of GPC5 markedly inhibited the proliferation, invasion and Wnt/β-catenin signaling of glioma cell lines. GPC5 was identified as a target gene of microRNA-301b (miR-301b). Further data showed that miR-301b expression was significantly up-regulated in glioma tissues and cell lines. In addition, miR-301b expression was inversely correlated with GPC5 expression in clinical glioma tissues. The overexpression of miR-301b promoted the proliferation, invasion and Wnt/β-catenin signaling of glioma cell lines, whereas the inhibition of miR-301b showed the opposite effect. However, the silencing of GPC5 significantly reversed the antitumor effect of miR-301b inhibition. Overall, our results revealed a tumor suppressive role of GPC5 in glioma and suggested that GPC5 expression was regulated by miR-301b. Our study indicates that the inhibition of miR-301b represses the proliferation and invasion of glioma cells by up-regulating GPC5 expression.

The expression of Mirc1/Mir17-92 cluster in sputum samples correlates with pulmonary exacerbations in cystic fibrosis patients

INTRODUCTION

Cystic fibrosis (CF) is a multi-organ disorder characterized by chronic sino-pulmonary infections and inflammation. Many patients with CF suffer from repeated pulmonary exacerbations that are predictors of worsened long-term morbidity and mortality. There are no reliable markers that associate with the onset or progression of an exacerbation or pulmonary deterioration. Previously, we found that the Mirc1/Mir17-92a cluster which is comprised of 6 microRNAs (Mirs) is highly expressed in CF mice and negatively regulates autophagy which in turn improves CF transmembrane conductance regulator (CFTR) function. Therefore, here we sought to examine the expression of individual Mirs within the Mirc1/Mir17-92 cluster in human cells and biological fluids and determine their role as biomarkers of pulmonary exacerbations and response to treatment.

METHODS

Mirc1/Mir17-92 cluster expression was measured in human CF and non-CF plasma, blood-derived neutrophils, and sputum samples. Values were correlated with pulmonary function, exacerbations and use of CFTR modulators.

RESULTS

Mirc1/Mir17-92 cluster expression was not significantly elevated in CF neutrophils nor plasma when compared to the non-CF cohort. Cluster expression in CF sputum was significantly higher than its expression in plasma. Elevated CF sputum Mirc1/Mir17-92 cluster expression positively correlated with pulmonary exacerbations and negatively correlated with lung function. Patients with CF undergoing treatment with the CFTR modulator Ivacaftor/Lumacaftor did not demonstrate significant change in the expression Mirc1/Mir17-92 cluster after six months of treatment.

CONCLUSIONS

Mirc1/Mir17-92 cluster expression is a promising biomarker of respiratory status in patients with CF including pulmonary exacerbation.

Nanotechnology based approaches for detection and delivery of microRNA in healthcare and crop protection

Nanobiotechnology has the potential to revolutionize diverse sectors including medicine, agriculture, food, textile and pharmaceuticals. Disease diagnostics, therapeutics and crop protection strategies are fast emerging using nanomaterials preferably nanobiomaterials. It has potential for development of novel nanobiomolecules which offer several advantages over conventional treatment methods. RNA nanoparticles with many unique features are promising candidates in disease treatment. The miRNAs are involved in many biochemical and developmental pathways and their regulation in plants and animals. These appear to be a powerful tool for controlling various pathological diseases in human, plants and animals, however there are challenges associated with miRNA based nanotechnology. Several advancements made in the field of miRNA therapeutics make it an attractive approach, but a lot more has to be explored in nanotechnology assisted miRNA therapy. The miRNA based technologies can be employed for detection and combating crop diseases as well. Despite these potential advantages, nanobiotechnology applications in the agricultural sector are still in its infancy and have not yet made its mark in comparison with healthcare sector. The review provides a platform to discuss nature, role and use of miRNAs in nanobiotechnology applications.

Decoding colorectal cancer epigenomics

Colorectal cancer (CRC) is very heterogeneous and presents different types of epigenetic alterations including DNA methylation, histone modifications and microRNAs. These changes are considered as characteristics of various observed clinical phenotypes. Undoubtedly, the discovery of epigenetic pathways with novel epigenetic-related mechanisms constitutes a promising advance in cancer biomarker discovery. In this review, we provide an evidence-based discussing of the current understanding of CRC epigenomics and its role in initiation, epithelial-to-mesenchymal transition and metastasis. We also discuss the recent findings regarding the potential clinical perspectives of these alterations as potent biomarkers for CRC diagnosis, prognosis, and therapy in the era of liquid biopsy.

Nano-based delivery of RNAi in cancer therapy

Background

RNA interference (RNAi), a newly developed method in which RNA molecules inhibit gene expression, has recently received considerable research attention. In the development of RNAi-based therapies, nanoparticles, which have distinctive size effects along with facile modification strategies and are capable of mediating effective RNAi with targeting potential, are attracting extensive interest.

Objective

This review presents an overview of the mechanisms of RNAi molecules in gene therapy and the different nanoparticles used to deliver RNAi molecules; briefly describes the current uses of RNAi in cancer therapy along with the nano-based delivery of RNA molecules in previous studies; and highlights some other carriers that have been applied in clinical settings. Finally, we discuss the nano-based delivery of RNAi therapeutics in preclinical development, including the current status and limitations of anti-cancer treatment.

Conclusion

With the growing number of RNAi therapeutics entering the clinical phase, various nanocarriers are expected to play important roles in the delivery of RNAi molecules for cancer therapeutics.

Preliminary evaluation of circulating microRNAs as potential biomarkers in paracoccidioidomycosis

MicroRNAs (miRNAs) are small RNAs (length, 19-24 nucleotides) that regulate gene expression by either mRNA degradation or translational inhibition of proteins. Circulating miRNAs, which are extremely stable and protected from RNAse-mediated degradation in body fluids, have appeared as candidate biomarkers for numerous diseases. However, little is known about circulating miRNAs in fungal infections. Paracoccidioidomycosis (PCM) is caused by the Paracoccidioides species, and is endemic in Central and South America, with predominance in adult male workers from rural areas. The current study aimed to identify a serum miRNA expression profile that could serve as a novel diagnostic biomarker for PCM. Total RNA was isolated and the levels of circulating miRNAs were compared between patients with PCM and healthy control subjects using reverse transcription-quantitative polymerase chain reaction. Bioinformatic analysis was used to evaluate the potential roles of these miRNAs in PCM. Eight miRNAs were differentially expressed in serum samples from patients with PCM. These miRNAs are associated with apoptosis and immune response. The identified miRNAs facilitate with understanding the regulatory mechanisms involved in the host-parasite interaction of PCM. Furthermore, considering that the diagnosis of PCM presents difficulties, these miRNAs may serve as novel biomarkers for this disease.

Meta-analysis of the prognostic value of abnormally expressed lncRNAs in hepatocellular carcinoma

Many long noncoding RNAs (lncRNAs) have been reported to be abnormally expressed in hepatocellular carcinoma (HCC), and may have the potential to serve as prognostic markers. In this study, a meta-analysis was conducted to systematically evaluate the prognostic value of various lncRNAs in HCC. Eligible literatures were systematically collected from PubMed, Embase, Web of Science, and Cochrane Library (up to December 30, 2015). The main outcomes including overall survival, relapse-free survival, and disease-free survival were analyzed. Pooled hazard ratios (HRs) and 95% confidence intervals (95% CIs) were calculated using random- or fixed-effects models. A total of 2,991 patients with HCC in People's Republic of China from 27 studies were included in the analysis. The level of lncRNAs showed a significant association with clinical outcomes. Abnormally elevated lncRNA transcription level predicted poor overall survival (HR: 1.68, 95% CI: 1.20-2.34, P=0.002; I (2)=75.5%, P=0.000) and relapse-free survival (HR: 2.08, 95% CI: 1.65-2.61, P<0.001; I (2)=24.0%, P=0.215), while no association was observed with disease-free survival of HCC patients (HR: 1.39, 95% CI: 0.51-3.78, P=0.524; I (2)=81.3%, P=0.005). Subgroup analysis further showed that lncRNA transcription level was significantly associated with tumor size (relative risk [RR]: 1.19, 95% CI: 1.01-1.39, P=0.035), microvascular invasion (RR: 1.44, 95% CI: 1.10-1.89, P=0.009), and portal vein tumor thrombus (RR: 1.50, 95% CI: 1.03-2.20, P=0.036). Publication bias and sensitivity analysis further confirmed the stability of our results. Our present meta-analysis indicates that abnormal lncRNA transcription level may serve as a promising indicator for prognostic evaluation of patients with HCC in People's Republic of China.

MiRNA-183-5p promotes cell proliferation and inhibits apoptosis in human breast cancer by targeting the PDCD4

MicroRNAs are often aberrantly expressed in breast cancer and postulated to play a causal role in the onset and maintenance of breast cancer by binding to its target mRNA. Here, we evaluated the effects of miRNA-183-5p on cell proliferation and apoptosis which attempted to elucidate the potential role of miR-183-5p/PDCD4 axis in human breast cancer. We found that the miR-183-5p expression level was extremely promoted in breast cancer in comparison with the adjacent normal tissues. Overexpression of miR-183-5p significantly enhanced the cell proliferation and inhibited cell apoptosis in MCF-7 and MDA-MB-231 cells. Moreover, PDCD4 was predicted as a putative target of miR-183-5p by bioinformatic approaches, and miR-183-5p negatively regulated the expression of PDCD4. Furthermore, knockdown of PDCD4 suppressed expression of p21 and p27, which was consistent with the result of the attachment of miR-183-5p. These data collectively demonstrate that miR-183-5p exerts oncomiRs effects in breast cancer, and may have broad impacts on the field of using antimiRs as anti-cancer drugs for breast cancer.

The diagnosis, prognosis, and therapeutic application of MicroRNAs in haematological malignancies

OBJECTIVE

MicroRNAs (miRNAs) are small noncoding RNA molecules that participate in vital cell processes such as proliferation, apoptosis, and differentiation. In recent years, they have been proven to play vital roles in haematological malignancies. In this review we briefly introduce some basic knowledge of microRNAs and summarize their ectopic expression in haematological malignancies, especially in leukaemia. We will also discuss the potential of microRNAs in the diagnosis of leukaemia, in the determination of the clinical prognosis of diverse subtypes, and in targeted therapy.

DISCUSSION

Despite current adoption of novel biological agents combining traditional chemotherapy regimens, leukaemia remains to have undesirable clinical outcomes due to inaccurate diagnosis, invasiveness of the disease, and patients' intolerance to chemotherapy, thus brand new therapeutic directions are urgently needed. MiRNAs regulate gene expression by means of binding to the 3'-untranslated regions of corresponding mRNAs, leading to the degradation of targeted mRNA or the inhibition of translation. It has been confirmed that they can either function as tumour inhibitors, or may trigger tumourigenesis in certain situations, this specific dual characteristic undoubtedly attract scientists to explore their roles in haematological malignancies. It is of great necessity to summarize the roles of miRNAs in haematological malignancies diagnosis, prognosis evaluation, and clinical treatment.

CONCLUSIONS

Future studies may take full advantage of miRNAs detection in diagnosing, in choosing targeted biological therapy, and in avoiding predictable side effect, thus the overall survival rate and cure efficiency of leukaemia should improve.

miRNA-24-3p promotes cell proliferation and inhibits apoptosis in human breast cancer by targeting p27Kip1

MicroRNAs (miRNAs) are often aberrantly expressed in breast cancer and are postulated to play a role in its initiation and progression. In the present study, we found that the expression level of miR-24-3p was upregulated in breast cancer in comparison with the level in adjacent normal tissues. Overexpression of miR-24-3p was able to promote cell proliferation and inhibit cell apoptosis in MDA-MB-435 and MDA-MB-468 cells. With the bioinformatic method, we further identified that p27Kip1 is a direct target of miR-24-3p, and its protein level was negatively regulated by miR-24-3p. Therefore, the data reported here demonstrate that miR-24-3p is an important regulator in breast cancer, and imply that the miR-24-3p/p27Kip1 axis has potential as a therapeutic target for breast cancer.

Differential microRNA expression by Solexa sequencing in the sera of ovarian cancer patients

MicroRNAs are a class of small noncoding RNA which play important regulatory roles in a variety of cancers. MiRNA-specific expression profiles have been reported for several pathological conditions. In this study, we combined large scale parallel Solexa sequencing to identify 11 up-regulated miRNAs and 19 down-regulated miRNAs with computational techniques in the sera of ovarian cancer patients while using healthy serum as the control. Among the above, four miRNAs (miR-22, miR-93, miR-106b, miR-451) were validated by quantitative RT-PCR and found to be significantly aberrantly expressed in the serum of ovarian cancer patients (P<0.05). There were no significant differences between samples from cancer stage I/II and III/IV. However, the levels of miR-106b (p=0.003) and miR-451 (p=0.007) were significantly different in those patients under and over 51 yearsof age. MiR-451 and miR-93 were also specific when analyzed with reference to different levels of CA125. This study shows that Solexa sequencing provides a promising method for cancer-related miRNA profiling, and selectively expressed miRNAs could be used as potential serum-based biomarkers for ovarian cancer diagnosis.

High serum microRNA-335 level predicts aggressive tumor progression and unfavorable prognosis in pediatric acute myeloid leukemia

PURPOSE

MiRNA expression profiles previously showed the higher expression of microRNA(miR)-335 in bone marrow samples of pediatric acute myeloid leukemia (AML) patients than normal controls. Our aim was to investigate associations of miR-335 expression with tumor progression and prognosis in pediatric AML.

METHODS

Real-time quantitative PCR was performed to detect the expression of miR-335 in bone marrow mononuclear cells and serum obtained from patients with pediatric AML and healthy controls.

RESULTS

Expression levels of miR-335 in the bone marrow and serum of pediatric AML patients were both significantly higher than those in normal controls (both P < 0.001). Then, high serum miR-335 level occurred more frequently in French-American-British classification subtype M7 subtype than in other subtypes (P = 0.03). The expression of serum miR-335 in pediatric AML patients with unfavorable karyotypes was also significantly higher than those in intermediate and favorable groups (P = 0.008). Moreover, high serum miR-335 level was markedly associated with shorter relapse-free and overall survivals (both P < 0.001) of patients with pediatric AML. Furthermore, the multivariate analysis identified the serum miR-335 and cytogenetics risk as independent prognostic factors for both relapse-free and overall survivals. More importantly, the prognostic relevance of serum miR-335 expression was more obvious in the subgroup of patients with intermediate-risk cytogenetics.

CONCLUSION

Our data offer the convincing evidence for the first time that serum miR-335 level may be markedly and consistently increased in pediatric AML patients. Serum miR-335 may serve as a promising marker for monitoring the progression and predicting the clinical outcome of patients with this disease.

MicroRNA-874 inhibits cell proliferation and induces apoptosis in human breast cancer by targeting CDK9

It has been demonstrated that miR-874 plays important roles in many types of cancers. Nevertheless, its biological function in breast cancer remains largely unknown. In this study, we found that the expression level of miR-874 is down-regulated in breast cancer in comparison with the adjacent normal tissues. The overexpression of miR-874 is able to inhibit cell proliferation and induce cell apoptosis and cell cycle arrest in MCF7 and MDA-MB-231 cells. Using a bioinformatics method, we further show that CDK9 is a direct target of miR-874 and that its protein level is negatively regulated by miR-874. Therefore, the data reported in this manuscript demonstrate that miR-874 is an important regulator in breast cancer and imply that the miR-874/CDK9 axis has potential as a therapeutic target for breast cancer.

Circulating miR-1, miR-133a, and miR-206 levels are increased after a half-marathon run

CONTEXT

Circulating miRNAs are potential biomarkers that can be important molecules driving cell-to-cell communication.

OBJECTIVE

To investigate circulating muscle-specific miRNAs in recreational athletes.

MATERIALS AND METHODS

Three miRNAs from whole plasma before and after a half-marathon were analyzed by qPCR.

RESULTS

MiR-1, -133a, and -206 significantly increased after the race.

DISCUSSION

Increased levels of miRNAs after exercise point to potential biomarkers and to the possibility of being functional players following endurance training.

CONCLUSION

These miRNAs are potential biomarkers of muscle damage or adaptation to exercise.

SMMRNA: a database of small molecule modulators of RNA

We have developed SMMRNA, an interactive database, available at http://www.smmrna.org, with special focus on small molecule ligands targeting RNA. Currently, SMMRNA consists of ∼770 unique ligands along with structural images of RNA molecules. Each ligand in the SMMRNA contains information such as Kd, Ki, IC50, ΔTm, molecular weight (MW), hydrogen donor and acceptor count, XlogP, number of rotatable bonds, number of aromatic rings and 2D and 3D structures. These parameters can be explored using text search, advanced search, substructure and similarity-based analysis tools that are embedded in SMMRNA. A structure editor is provided for 3D visualization of ligands. Advance analysis can be performed using substructure and OpenBabel-based chemical similarity fingerprints. Upload facility for both RNA and ligands is also provided. The physicochemical properties of the ligands were further examined using OpenBabel descriptors, hierarchical clustering, binning partition and multidimensional scaling. We have also generated a 3D conformation database of ligands to support the structure and ligand-based screening. SMMRNA provides comprehensive resource for further design, development and refinement of small molecule modulators for selective targeting of RNA molecules.

miR-29b negatively regulates human osteoclastic cell differentiation and function: implications for the treatment of multiple myeloma-related bone disease

Skeletal homeostasis relies upon a fine tuning of osteoclast (OCL)-mediated bone resorption and osteoblast (OBL)-dependent bone formation. This balance is unsettled by multiple myeloma (MM) cells, which impair OBL function and stimulate OCLs to generate lytic lesions. Emerging experimental evidence is disclosing a key regulatory role of microRNAs (miRNAs) in the regulation of bone homeostasis suggesting the miRNA network as potential novel target for the treatment of MM-related bone disease (BD). Here, we report that miR-29b expression decreases progressively during human OCL differentiation in vitro. We found that lentiviral transduction of miR-29b into OCLs, even in the presence of MM cells, significantly impairs tartrate acid phosphatase (TRAcP) expression, lacunae generation, and collagen degradation, which are relevant hallmarks of OCL activity. Accordingly, expression of cathepsin K and metalloproteinase 9 (MMP9) as well as actin ring rearrangement were impaired in the presence of miR-29b. Moreover, we found that canonical targets C-FOS and metalloproteinase 2 are suppressed by constitutive miR-29b expression which also downregulated the master OCL transcription factor, NAFTc-1. Overall, these data indicate that enforced expression of miR-29b impairs OCL differentiation and overcomes OCL activation triggered by MM cells, providing a rationale for miR-29b-based treatment of MM-related BD.

Increased expression of microRNA-335 predicts a favorable prognosis in primary gallbladder carcinoma

Background

MicroRNAs (miRNAs) display aberrant expression patterns and functional abnormalities in many types of cancer. However, their roles in primary gallbladder carcinoma (PGC) have not been well documented. miR-335 has been demonstrated to be involved in tumorigenesis of several cancers in the digestive system. The aim of this study was to investigate the clinical significance of miR-335 in PGC.

Methods

miR-335 expression in 166 human PGC tissues and matched adjacent nondysplastic gallbladder epithelia was measured by real-time quantitative polymerase chain reaction (RT-PCR) assay.

Results

The expression level of miR-335 was significantly lower in PGC tissues than that in nondysplastic gallbladder epithelia (P<0.001). Of 166 PGC patients, 96 (57.83%) had reduced expression of miR-335. Additionally, the expression of miR-335 was significantly lower in PGC tissues with high histologic grade (P=0.02), advanced pathologic T stage (P=0.009) and clinical stage (P=0.008), and with positive lymph node metastasis (P=0.001). In univariate analysis by log-rank test, histologic grade (P=0.03), pathologic T stage (P=0.008), clinical stage (P=0.01), lymph node metastasis (P<0.001), and miR-335 expression (P<0.001) were significant prognostic factors for overall survival of PGC patients. Multivariate analysis further revealed that pathologic T stage (P=0.02), lymph node metastasis (P=0.008), and miR-335 expression (P=0.006) maintained independent prognostic influence on overall survival.

Conclusion

This study offers convincing evidence for the first time that miR-335 was downregulated in a majority of PGC patients and may be associated with the aggressive tumor behaviors. Loss of miR-335 expression may be a useful marker for clinical outcome and a therapeutic target for PGC.

Briefing in family characteristics of microRNAs and their applications in cancer research

MicroRNAs (miRNAs) are endogenous, short, non-coding RNA molecules that are directly involved in the post-transcriptional regulation of gene expression. Dysregulation of miRNAs is usually associated with diseases. Since miRNAs in a family intend to have common functional characteristics, proper assignment of miRNA family becomes heuristic for better understanding of miRNA nature and their potentials in clinic. In this review, we will briefly discuss the recent progress in miRNA research, particularly its impact on protein and its clinical application in cancer research in a view of miRNA family. This article is part of a Special Issue entitled: Computational Proteomics, Systems Biology & Clinical Implications. Guest Editor: Yudong Cai.

Identification and characterization of microRNAs in Baylisascaris schroederi of the giant panda

Background

Baylisascaris schroederi is one of the most significant threats to the giant panda’s survival, responsible for half of the deaths reported from 2001 to 2005. MicroRNA (miRNA) has been identified as one of the key factors for gene regulations at the post-transcriptional level, and also considered as a potential control and treatment target against infectious diseases.

Methods

The present study investigated the miRNA profile of B. schroederi via high throughput sequencing and real-time quantitative PCR.

Results

A total of 18.07 million raw reads were obtained and 18.01 million were identified with high quality. By analysis of standard stem-loop structures, 108 miRNA candidates were predicted, including 60 known miRNAs and 48 novel ones. Target prediction revealed that the “chitinase” was the most abundant target with 483 sequences, and 263 targets were related to ovarian and egg development. The ribosomal protein related sequences occupied 449 sequences.

Conclusions

Previous studies have shown that some parasites secrete chitinases for exsheathment and/or for penetrating the peritrophic matrix of the host. It therefore seems that B. schroederi may be effectively regulated by miRNAs for development, invasion, and reproduction. Given that chitinases have been identified as important biological control agents for pests, identification of microRNAs in B. schroederi of the giant panda would provide useful information for the development of biological control strategies and/or vaccines against B. schroederi infection in the giant panda.

Upregulation of microRNA-375 is associated with poor prognosis in pediatric acute myeloid leukemia

A genome-wide serum miRNA expression analysis previously showed the upregulation of microRNA-375 (miR-375) in acute myeloid leukemia (AML) patients compared with healthy controls. The aim of this study was to investigate the expression patterns and the prognostic relevance of miR-375 in pediatric AML. Expression levels of miR-375 in bone marrow mononuclear cells were detected by real-time quantitative PCR in a cohort of 106 patients with newly diagnosed pediatric AML. Expression levels of miR-375 in the bone marrow of pediatric AML patients were significantly higher than those in normal controls (P < 0.001). Then, miR-375 upregulation occurred more frequently in French-American-British classification subtype M7 than in other subtypes (P < 0.001). Regarding to cytogenetic risk, the expression levels of miR-375 in pediatric AML patients with unfavorable karyotypes were dramatically higher than those in intermediate and favorable groups (P = 0.002). Moreover, high miR-375 expression was significantly associated with shorter relapse-free survival (P < 0.001) and overall survival (P < 0.001) in pediatric AML patients. Multivariate analysis further identified miR-375 expression and cytogenetics risk as independent prognostic factors for both relapse-free survival and overall survival. In particular, the prognostic relevance of miR-375 expression was more obvious in the subgroup of patients with intermediate-risk cytogenetics. Our findings suggest for the first time that the upregulation of miR-375 may be one of the molecular mechanisms involved in the development and progression of pediatric AML. Since its correlation with poor relapse-free survival and overall survival, miR-375 may be a novel biomarker to improve the management of pediatric AML patients.

Nanoparticle-mediated delivery of therapeutic genes: focus on miRNA therapeutics

INTRODUCTION

Micro RNAs (miRNA) are 21 - 23 nucleotides long and regulate the expression of coding genes by binding imperfectly with their 3' UTR region. The miRNA profile is altered in pathological processes, making miRNAs good targets for drug therapy. Restoration of down-regulated miRNA or inhibition of overexpressed miRNA to return miRNA to its normal state is the basis of miRNA-based therapy. This review focuses on nanocarriers used for the delivery of miRNA that confer physical stability to the unstable RNA structure, protect the RNA from nuclease degradation and aid in effective silencing of target genes.

AREAS COVERED

The necessity of the nanocarrier for the delivery of the miRNA is emphasized and the recent research on liposome-, metal- and polymer-mediated miRNA delivery for the inhibition or replacement of the disease-related miRNA is summarized.

EXPERT OPINION

The size, charge and surface properties of nanocarriers have to be tuned to ensure effective and safe delivery of the miRNA in clinical practice. The immune responses related to the nanocarriers and the double-stranded nucleotide delivery remain to be addressed. Also, the binding of miRNAs to non-specific targets has to be studied in more detail because miRNAs have multiple targets due to partial binding unlike siRNA.

Roles of long noncoding RNAs in brain development, functional diversification and neurodegenerative diseases

Long noncoding RNAs (lncRNAs) have been attracting immense research interest, while only a handful of lncRNAs have been characterized thoroughly. Their involvement in the fundamental cellular processes including regulate gene expression at epigenetics, transcription, and post-transcription highlighted a central role in cell homeostasis. However, lncRNAs studies are still at a relatively early stage, their definition, conservation, functions, and action mechanisms remain fairly complicated. Here, we give a systematic and comprehensive summary of the existing knowledge of lncRNAs in order to provide a better understanding of this new studying field. lncRNAs play important roles in brain development, neuron function and maintenance, and neurodegenerative diseases are becoming increasingly evident. In this review, we also highlighted recent studies related lncRNAs in central nervous system (CNS) development and neurodegenerative diseases, including Alzheimer's disease (AD), Parkinson's disease (PD), Huntington's disease (HD) and amyotrophic lateral sclerosis (ALS), and elucidated some specific lncRNAs which may be important for understanding the pathophysiology of neurodegenerative diseases, also have the potential as therapeutic targets.

MicroRNA and signal transduction pathways in tumor radiation response

Tumor radiation response is an essential issue in radiotherapy and a core determining factor of tumor radioresistance or radiosensitivity. Multiple factors can influence tumor radiation response, and among them tumor genetic and epigenetic background, tumor microenvironment and tumor blood flow status may take a leading role. During the whole process of tumor radiation response, tumor radiosensitivity can be regulated in an orderly manner through some classical signal transduction pathways. Although these pathways have already owned multiple biological functions and involved in the process of carcinogenesis, their regulatory roles in tumor radiation response can not be ignored. MicroRNA (miRNA) is a class of non-coding RNA of about 22 nucleotides in length, which binds to the 3'-untranslated region (3'-UTR) of target gene and controls the expression of it at the post-transcriptional level. MiRNA participates in numerous physiology and pathology processes and acts as oncogene or tumor suppressor to affect cancer progression. Through interplaying with the key components in radiation related signal transduction pathways, miRNA could effectively activate the expression of DNA damage response genes and cell cycle related genes in the nucleus, and play a critical role in the modulation of radiation response and radiosensitivity in tumor cells. In this review, we mainly elucidate the regulatory mechanisms and functions of miRNA in these radiation related signal transduction pathways from three different aspects which include the upstream receptors, midstream transducer pathways, and downstream effector genes.

MicroRNAs in osteosarcoma: From biological players to clinical contributors, a review

Osteosarcoma is a primary malignant bone tumour with high morbidity that occurs mainly in children and adolescents. While the molecular basis of osteosarcoma has received considerable attention, the cellular and molecular mechanisms underlying pre- and postoperative metastasis formation and the development of chemoresistance remain unclear. MicroRNAs (miRNAs), a class of 22-nucleotide noncoding RNAs, have emerged as critical components of gene-regulatory networks controlling numerous important pathophysiological processes, including the initiation and progression of cancers. Studies on miRNAs have opened new avenues for both the diagnosis and treatment of cancer. This review discusses the roles of miRNAs in osteosarcoma and their potential applications for the diagnosis, prognosis and treatment of this malignancy. As a rapidly evolving field of basic and biomedical science, miRNA research will have a revolutionary impact on the management of osteosarcoma.

HDL drug carriers for targeted therapy

Plasma concentrations of high-density lipoprotein cholesterol (HDL-C) are strongly and inversely associated with cardiovascular risk. HDL is not a simple lipid transporter, but possesses multiple anti-atherosclerosis activities because it contains special proteins, signaling lipid, and microRNAs. Natural or recombinant HDLs have emerged as potential carriers for delivering a drug to a specified target. However, HDL function also depends on enzymes that alter its structure and composition, as well as cellular receptors and membrane micro-domains that facilitate interactions with the microenvironment. In this review, four mechanisms predicted to enhance functions or targeted therapy of HDL in vivo are discussed. The first involves caveolae-mediated recruitment of HDL signal to bind their receptors. The second involves scavenger receptor class B type I (SR-BI) mediating anchoring and fluidity for signal-lipid of HDL. The third involves lecithin-cholesterol acyltransferase (LCAT) concentrating the signaling lipid at the surface of the HDL particle. The fourth involves microRNAs (miRNAs) being delivered in the blood to special targets by HDL. Exploitation of these four mechanisms will promote HDL to carry targeted drugs and increase HDL's clinical value.

Prognostic value of miR-29a expression in pediatric acute myeloid leukemia

OBJECTIVES

As a member of miR-29 family, miR-29a can act as either oncogene or tumor suppressor. However, its expression patterns in acute myeloid leukemia (AML) are controversial according to previous studies. Thus, the aim of this study was to determine the expression and clinical significance of miR-29a in pediatric AML.

METHODS

Expression levels of miR-29a in bone marrow mononuclear cells were detected by real-time quantitative PCR in a cohort of 106 patients with newly diagnosed pediatric AML. The prognostic values of miR-29a in pediatric AML were also analyzed.

RESULTS

Compared with normal controls, we demonstrated a significantly decreased expression of miR-29a in the bone marrow of pediatric AML patients (P<0.001). The expression levels of miR-29a were significantly lower in French-American-British classification subtype M7 than in other subtypes (P<0.001) and differed significantly across cytogenetic risk groups (P=0.002) with high miR-29a expression among those with favorable karyotypes. Moreover, low miR-29a expression was significantly associated with shorter relapse-free (P<0.001) and overall (P=0.008) survival in pediatric AML patients. Cox proportional hazards multivariate analysis of the univariate predictors identified cytogenetic risk and miR-29a expression as independent prognostic factors for relapse-free survival and overall survival. More interestingly, the prognostic value of miR-29a expression was more obvious in the subgroup of patients with intermediate-risk cytogenetics.

CONCLUSION

Our data indicate for the first time that the down-regulation of miR-29a was associated with advanced clinical features and poor prognosis of pediatric AML patients, suggesting that miR-29a down-regulation may be used as an unfavorable prognostic marker in pediatric AML.

Oxidative stress in apoptosis and cancer: an update

The oxygen paradox tells us that oxygen is both necessary for aerobic life and toxic to all life forms. Reactive oxygen species (ROS) touch every biological and medical discipline, especially those involving proliferative status, supporting the idea that active oxygen may be increased in tumor cells. In fact, metabolism of oxygen and the resulting toxic byproducts can cause cancer and death. Efforts to counteract the damage caused by ROS are gaining acceptance as a basis for novel therapeutic approaches, and the field of prevention of cancer is experiencing an upsurge of interest in medically useful antioxidants. Apoptosis is an important means of regulating cell numbers in the developing cell system, but it is so important that it must be controlled. Normal cell death in homeostasis of multicellular organisms is mediated through tightly regulated apoptotic pathways that involve oxidative stress regulation. Defective signaling through these pathways can contribute to both unbalance in apoptosis and development of cancer. Finally, in this review, we discuss new knowledge about recent tools that provide powerful antioxidant strategies, and designing methods to deliver to target cells, in the prevention and treatment of cancer.

Aberrant expression of microRNAs in gastric cancer and biological significance of miR-574-3p

The discovery of microRNAs (miRNAs) provides a new and powerful tool for studying the mechanisms, diagnosis and treatments of cancer. In this study, we employed AFFX miRNA expression chips to search for miRNAs that may be aberrantly expressed in gastric cancer tissues and to investigate the potential roles that miRNAs may play in the development and progression of gastric cancer. 14 miRNAs were found to be down-regulated and 2 miRNAs up-regulated in gastric cancer tissues compared to the normal gastric tissues. Among the aberrantly expressed miRNAs, miR-574-3p was selected to further study its expression features and functional roles. Interestingly, the reduced expression of miR-574-3p occurred mainly in the early stages of gastric cancer or in cancers with high level of differentiation, suggesting that it can be used as a marker for a mild case of gastric cancer. Functional study revealed that cell proliferation, migration and invasion were significantly inhibited in miR-574-3p-transfected gastric cancer SGC7901 cells. Computational prediction and experimental validation suggest that Cullin2 may be one of the targets of miR-574-3p. Overall our study suggests that the aberrantly expressed miRNAs may play regulatory and functional roles in the development and progression of gastric cancer.