miR-20a promotes proliferation and invasion by targeting APP in human ovarian cancer cells

ADAM10 is overexpressed in human hepatocellular carcinoma and contributes to the proliferation, invasion and migration of HepG2 cells

The overexpression of A disintegrin and metalloproteinase 10 (ADAM10) has been found to be closely associated with the development and progression of various types of tumors. However, ADAM10 expression in hepatocellular carcinoma (HCC) and its significance remain largely unknown. The present study aimed to investigate the expression of ADAM10 in human HCC and the effect of ADAM10 gene silencing by siRNA on the proliferation, invasion and migration of HepG2 human hepatoma cells. Immunohistochemistry was performed to examine the expression of ADAM10 in human HCC tissues and in the adjacent non-cancer tissues from 30 patients with HCC. RNA interference was used to knock down ADAM10 expression in HepG2 human hepatoma cells and the proliferation and migration as well as the invasive ability of the treated cells were observed in vitro. The expression of ADAM10 protein in HCC tissues was significantly higher when compared to that in adjacent non-tumor tissues (P<0.05). The high expression of ADAM10 in cancer was significantly correlated with clinical outcomes (P<0.05). Silencing of ADAM10 resulted in inhibition of proliferation and migration as well as invasion of HepG2 human hepatoma cells (P<0.05). These studies suggest that ADAM10 plays an important role in regulating proliferation, invasion and migration of HepG2 cells. High expression of ADAM10 may be a valuable predictive factor for HCC prognosis, and ADAM10 is potentially an important therapeutic target for the prevention of tumor development and progression in HCC.

Serum microRNA expression levels can predict lymph node metastasis in patients with early-stage cervical squamous cell carcinoma

Circulating microRNA expression levels can serve as diagnostic/prognostic biomarkers in several types of malignant tumors; however, to our knowledge, there have been reports describing their value in cervical squamous cell carcinoma (SCC). In this study, we used hybridization arrays to compare the microRNA expression profiles in cervical squamous cell carcinomas (SCC) samples among patients with lymph node metastasis (LNM) or without LNM; 89 microRNAs were found to fit our inclusion criteria. Using quantitative PCR (qPCR), we examined the expression levels of these microRNAs in cervical cancer tissue, as well as in serum from patients and healthy women. We compared the expression levels between patients with LNM (n=40) and those without LNM (n=40) and healthy controls (n=20). Using regression analysis, we generated a comprehensive set of marker microRNAs and drew the fitted binormal receiver operating characteristic (ROC) curves to access the predictive value. We identified 6 serum microRNAs that can predict LNM in cervical SCC patients; these microRNAs were miR-1246, miR-20a, miR-2392, miR-3147, miR-3162-5p and miR-4484. The area under the curve (AUC) of the comprehensive set of serum microRNAs predicting LNM was 0.932 (sensitivity, 0.856; specificity, 0.850). The predictive value of the serum microRNAs was inferior to that in tissue (AUC 0.992; sensitivity, 0.967; specificity, 0.950; P=0.018). We compared the LNM predictive value of serum microRNAs and SCC antigen (SCC-Ag) by drawing fitted binormal ROC curves However, serum microRNA analysis is by far superior to serum SCC-Ag analysis (AUC 0.713; sensitivity, 0.612; specificity, 0.700; P<0.0001). Serum microRNAs are a good predictor of LNM with clinical value in early-stage cervical SCC.

miR-335 represents an invasion suppressor gene in ovarian cancer by targeting Bcl-w

microRNAs (miRNAs) are a class of non-coding small RNAs that bind to target mRNAs, usually resulting in post-transcriptional repression by translational inhibition or target degradation. mRNAs can function as tumor suppressors or oncogenes (also referred to as oncomirs) in human tumors. Although aberrant expression of miR-335 has been reported in ovarian cancer, whether it is an active participant or a mere bystander remains unknown. To clarify its role in ovarian carcinogenesis, we first examined the relative expression of miR-335 in 17 normal ovarian tissues and 4 ovarian cancer cell lines using qPCR. We found that miR-335 was downregulated in the ovarian cancer cell lines relative to normal ovarian epithelium tissues. In vitro, overexpression of miR-335 suppressed cell migration and invasion and resulted in depolymerization of F-actin in ovarian cancer cell lines, but exhibited a negligible effect on cell proliferation. B-cell CLL/lymphoma 2 like 2 (Bcl-w or BCL2L2), a pro-survival member of the Bcl-2 protein family, was identified as a potential target of miR-335 according to the results of bioinformatic analysis, and the expression of Bcl-w and its effector matrix metalloproteinase-2 (MMP‑2) was downregulated after transfection with miR-335 mimics. In addition, ectopic Bcl-w could almost fully nullify the effect of miR-335 overexpression on ovarian cancer cell migration and invasion. These findings indicate that the tiny genome product, miR-335, whose lack of expression brings about the abnormal accumulation of Bcl-w and subsequent unchecked cell invasion in ovarian cancer, may help us to understand one of the many steps ovarian cells take on their way toward the acquisition of malignant phenotypes and miR-335 may be a promising predictor of survival.

Differential distribution of miR-20a and miR-20b may underly metastatic heterogeneity of breast cancers

BACKGROUND

The discovery that microRNA (miRNA) regulates metastasis provide a principal molecular basis for tumor heterogeneity. A characteristic of solid tumors is their heterogenous distribution of blood vessels, with significant hypoxia occurring in regions (centers of tumor) of low blood flow. It is necessary to discover the mechanism of breast cancer metastasis in relation to the fact that there is a differential distribution of crucial microRNA in tumors from centers to edges.

METHODS

Breast tissues from 48 patients (32 patients with breast cancer) were classified into the high invasive and metastatic group (HIMG), low invasive and metastatic group (LIMG), and normal group. Samples were collected from both the centers and edges of all tumors. The first six specimens were detected by microRNA array, and the second ten specimens were detected by real-time qRT- PCR and Western blot analyses. Correlation analysis was performed between the miRNAs and target proteins.

RESULTS

The relative content of miR-20a and miR-20b was lower in the center of the tumor than at the edge in the LIMG, lower at the edge of the tumor than in the center in the HIMG, and lower in breast cancer tissues than in normal tissues. VEGF-A and HIF-1alpha mRNA levels were higher in the HIMG than in the LIMG, and levels were higher in both groups than in the normal group; there was no difference in mRNA levels between the edge and center of the tumor. VEGF-A and HIF-1alpha protein levels were higher in the HIMG than in the LIMG, and protein levels in both groups were higher than in the normal group; there was a significant difference in protein expression between the edge and center of the tumor. Correlation analysis showed that the key miRNAs (miR-20a and miR-20b) negatively correlated with the target proteins (VEGF-A and HIF-1alpha).

CONCLUSIONS

Our data suggest that miR-20a and miR-20b are differentially distributed in breast cancer, while VEGF-A and HIF-1alpha mRNA had coincident distributions, and VEGF-A and HIF-1alpha proteins had uneven and opposing distributions to the miRNAs. It appears that one of the most important facets underlying metastatic heterogeneity is the differential distribution of miR-20a and miR-20b and their regulation of target proteins.

Decoding the non-coding RNAs in Alzheimer's disease

Non-coding RNAs (ncRNAs) are integral components of biological networks with fundamental roles in regulating gene expression. They can integrate sequence information from the DNA code, epigenetic regulation and functions of multimeric protein complexes to potentially determine the epigenetic status and transcriptional network in any given cell. Humans potentially contain more ncRNAs than any other species, especially in the brain, where they may well play a significant role in human development and cognitive ability. This review discusses their emerging role in Alzheimer's disease (AD), a human pathological condition characterized by the progressive impairment of cognitive functions. We discuss the complexity of the ncRNA world and how this is reflected in the regulation of the amyloid precursor protein and Tau, two proteins with central functions in AD. By understanding this intricate regulatory network, there is hope for a better understanding of disease mechanisms and ultimately developing diagnostic and therapeutic tools.

Suppression of CX43 expression by miR-20a in the progression of human prostate cancer

The aberrant expression of microRNAs (miRNAs) has been found in various types of cancer. The present study found miR-20a to be significantly upregulated in prostate cancer compared with normal prostate tissues. The proliferation and colony formation assays revealed that the downregulation of miR-20a by miR-20a inhibitor suppresses the proliferation of MDA-PCa-2b cells in vitro and also inhibits tumor growth in vivo. Furthermore, a gap junction protein, α 1 (CX43), was identified as a direct target gene of miR-20a. The upregulation of CX43 was detected in MDA-PCa-2b cells after treatment with miR-20a inhibitor both in vitro and in vivo. In conclusion, the findings show that miR-20a significantly contributes to the progression of prostate cancer by targeting CX43.

MicroRNA-153 physiologically inhibits expression of amyloid-β precursor protein in cultured human fetal brain cells and is dysregulated in a subset of Alzheimer disease patients

Regulation of amyloid-β (Aβ) precursor protein (APP) expression is complex. MicroRNAs (miRNAs) are expected to participate in the molecular network that controls this process. The composition of this network is, however, still undefined. Elucidating the complement of miRNAs that regulate APP expression should reveal novel drug targets capable of modulating Aβ production in AD. Here, we investigated the contribution of miR-153 to this regulatory network. A miR-153 target site within the APP 3'-untranslated region (3'-UTR) was predicted by several bioinformatic algorithms. We found that miR-153 significantly reduced reporter expression when co-transfected with an APP 3'-UTR reporter construct. Mutation of the predicted miR-153 target site eliminated this reporter response. miR-153 delivery in both HeLa cells and primary human fetal brain cultures significantly reduced APP expression. Delivery of a miR-153 antisense inhibitor to human fetal brain cultures significantly elevated APP expression. miR-153 delivery also reduced expression of the APP paralog APLP2. High functional redundancy between APP and APLP2 suggests that miR-153 may target biological pathways in which they both function. Interestingly, in a subset of human AD brain specimens with moderate AD pathology, miR-153 levels were reduced. This same subset also exhibited elevated APP levels relative to control specimens. Therefore, endogenous miR-153 inhibits expression of APP in human neurons by specifically interacting with the APP 3'-UTR. This regulatory interaction may have relevance to AD etiology, where low miR-153 levels may drive increased APP expression in a subset of AD patients.

MicroRNAs in Neurotoxicity

MicroRNAs are gaining importance as regulators of gene expression with the capability to fine-tune and modulate cellular events. The complex network with their selective targets (mRNAs/genes) pave way for regulation of many physiological processes. Dysregulation of normal neuronal activities could result in accumulation of substances that are detrimental to neuronal functions and subsequently result in neurotoxicity. Neurotoxicity-mediated pathophysiological conditions could then manifest as diseases or disabilities like Parkinson's and Alzheimer's which have debilitating implications. Such toxicity can be a result of individuals predisposed due to genetic inheritance or from other sources such as brain tumours. Neurotoxicity can also be brought about by external agents like drugs and alcohol as well as brain injury with miRNAs playing a pivotal role in diseases. It is therefore vital to understand the expression of these microRNAs and their impact on neuronal activities. In this paper, we discuss some of the neuronal pathophysiological conditions that could be caused by dysregulated microRNAs.

miR-20a promotes migration and invasion by regulating TNKS2 in human cervical cancer cells

miR-20a is an important member of the miR-17-92 cluster, and its real function in cervical cancer cells is unknown. Our study demonstrated that miR-20a was upregulated in cervical cancer tissues. Overexpression of miR-20a in cervical cancer-derived cell lines, HeLa and C-33A, enhanced long-term cellular proliferation, migration and invasion, whereas inhibition of miR-20a suppressed those functions. We also confirmed that oncogenic TNKS2 is directly upregulated by miR-20a. Furthermore, suppression of TNKS2 expression could inhibit colony formation, migration and invasion of cervical cancer cells. Therefore, we concluded that miR-20a can promote migration and invasion of cervical cancer cells through the upregulation of TNKS2.

Microribonucleic acids and gastric cancer

Gastric carcinogenesis is a multistep process involving genetic and epigenetic alteration of protein-coding proto-oncogenes and tumor-suppressor genes. Microribonucleic acids (miR) are a recently-described class of genes encoding small non-coding RNA molecules, which primarily act by downregulating the translation of target mRNA. It has become apparent that miR are also key factors in cancer, playing both oncogenic and tumor-suppressing roles in gastric cancer. Recent studies have shown that a substantial number of miR show differential expression in gastric cancer tissues, and they are turning out to be just like any other regulatory gene. In this connection, miR dysregulation are reported to be associated with incidence, early diagnosis and prognosis of gastric cancer. Therefore, investigation of the biological aspects of miR dysregulation might help us better understand the pathogenesis of gastric cancer and promote the development of miR-directed therapeutics against this deadly disease. The aim of the present review was to describe the mechanisms of several known miR, summarize recent studies on oncogenic miR (e.g. miR-21, miR-106a and miR-17), tumor suppressor miR (e.g. miR-101, miR-181, miR-449, miR-486, let-7a) and controversial roles of miR (e.g. miR-107, miR-126) for gastric cancer. In addition, their potential clinical applications and prospects in gastric cancer, such as biomarkers and clinical therapy tools, are also briefly discussed.

Microribonucleic acids and gastric cancer

Gastric carcinogenesis is a multistep process involving genetic and epigenetic alteration of protein-coding proto-oncogenes and tumor-suppressor genes. Microribonucleic acids (miR) are a recently-described class of genes encoding small non-coding RNA molecules, which primarily act by downregulating the translation of target mRNA. It has become apparent that miR are also key factors in cancer, playing both oncogenic and tumor-suppressing roles in gastric cancer. Recent studies have shown that a substantial number of miR show differential expression in gastric cancer tissues, and they are turning out to be just like any other regulatory gene. In this connection, miR dysregulation are reported to be associated with incidence, early diagnosis and prognosis of gastric cancer. Therefore, investigation of the biological aspects of miR dysregulation might help us better understand the pathogenesis of gastric cancer and promote the development of miR-directed therapeutics against this deadly disease. The aim of the present review was to describe the mechanisms of several known miR, summarize recent studies on oncogenic miR (e.g. miR-21, miR-106a and miR-17), tumor suppressor miR (e.g. miR-101, miR-181, miR-449, miR-486, let-7a) and controversial roles of miR (e.g. miR-107, miR-126) for gastric cancer. In addition, their potential clinical applications and prospects in gastric cancer, such as biomarkers and clinical therapy tools, are also briefly discussed.

Evaluation of microRNA expression profiles and their associations with risk alleles in lymphoblastoid cell lines of familial ovarian cancer

Interindividual variations of microRNA expression are likely to influence the expression of microRNA target genes and, therefore, contribute to phenotypic differences in humans, including cancer susceptibility. Whether microRNA expression variation has any role in ovarian cancer development is still unknown. Here, we evaluated microRNA expression profiles in lymphoblastoid cell lines from 74 women with familial ovarian cancer and 47 unrelated controls matched on gender and race. We found that the cases and unrelated controls can be clustered using 95 differentially expressed microRNAs with 91% accuracy. To assess the potential implications of microRNAs in ovarian cancer, we investigated the associations between microRNA expression and seven ovarian cancer risk variants discovered from genome-wide association studies (GWAS), namely, rs3814113 on 9p22.2, rs2072590 on 2q31, rs2665390 on 3q25, rs10088218, rs1516982, rs10098821 on 8q24.21 and rs2363956 on 19p13. We observed 130 significant associations at a permutation level of 0.01. Compared with other risk variants, rs3814113 and rs2072590 had the greatest number of significant associations (68 and 37, respectively). Interestingly, 14 microRNAs that were associated with ovarian cancer risk alleles belong to five microRNA clusters. The most notable cluster is the tumorigenic miR-17-92 cluster with five microRNAs, all of which are significantly associated with rs3814113. Using pathway analysis, several key biological pathways were significantly overrepresented, such as cellular response to stress (P = 2.87 × 10(-06)), etc. Further characterization of significant associations between microRNAs and risk alleles could facilitate the understanding of the functions of these GWAS discovered risk alleles in the genetic etiology of ovarian cancer.

Advances in microRNA experimental approaches to study physiological regulation of gene products implicated in CNS disorders

The central nervous system (CNS) is a remarkably complex organ system, requiring an equally complex network of molecular pathways controlling the multitude of diverse, cellular activities. Gene expression is a critical node at which regulatory control of molecular networks is implemented. As such, elucidating the various mechanisms employed in the physiological regulation of gene expression in the CNS is important both for establishing a reference for comparison to the diseased state and for expanding the set of validated drug targets available for disease intervention. MicroRNAs (miRNAs) are an abundant class of small RNA that mediates potent inhibitory effects on global gene expression. Recent advances have been made in methods employed to study the contribution of these miRNAs to gene expression. Here we review these latest advances and present a methodological workflow from the perspective of an investigator studying the physiological regulation of a gene of interest. We discuss methods for identifying putative miRNA target sites in a transcript of interest, strategies for validating predicted target sites, assays for detecting miRNA expression, and approaches for disrupting endogenous miRNA function. We consider both advantages and limitations, highlighting certain caveats that inform the suitability of a given method for a specific application. Through careful implementation of the appropriate methodologies discussed herein, we are optimistic that important discoveries related to miRNA participation in CNS physiology and dysfunction are on the horizon.

MicroRNAs as a novel cellular senescence regulator

Cellular senescence is a program activated in normal cells in response to various types of stresses and is manifested by permanent arrest of cell cycle. Cellular senescence is closely related to tumor suppression, and may contribute to the ageing of organisms. The complex senescence cell phenotype has many different mechanisms. Recent studies have provided important insights regarding the role played by miRNAs during cellular senescence as a novel molecular mechanism. In this article, we will review the latest advances in the identification and validation of senescence-regulatory miRNAs and the possible mechanisms.

MicroRNA-191 targets N-deacetylase/N-sulfotransferase 1 and promotes cell growth in human gastric carcinoma cell line MGC803

As a family of post-transcriptional regulator of gene expression, the microRNAs (miRNAs) control a wide array of biological processes including cell differentiation, proliferation and apoptosis, and the dysregulation of miRNAs is a hallmark of cancer. Here, we found that the microRNA-191 (miR-191) was at a high-expression level in human gastric adenocarcinoma cell line MGC803 and human gastric cancer tissues. The results of 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide and colony formation assays showed that miR-191 could promote cell growth and suppress apoptosis of MGC803 cells. The N-deacetylase/N-sulfotransferase 1 (NDST1) was confirmed to be a direct target gene of miR-191 by enhanced green fluorescent protein reporter experiment. The mRNA and protein levels of NDST1 were inversely correlated with miR-191 in MGC803 cells, suggesting the negative regulation of NDST1 by miR-191. Furthermore, NDST1 played an inhibitory role and could suppress MGC803 cell proliferation. Our findings suggested that miR-191 could act as an oncogene in MGC803 cells, and the cellular function was partially due to its negative regulation of NDST1.

The relationship of haplotype in lactotransferrin and its expression levels in Chinese Han ovarian cancer

Chromosomal DNA sequence polymorphisms may contribute to individuality, confer risk for diseases, and most commonly are used as genetic markers in association study. The iron-binding protein lactoferrin inhibits bacterial growth by sequestering essential iron and also exhibits antitumor, anti-inflammatory, and immunoregulatory activities. The gene coding for lactotransferrin (LTF) is polymorphic, with the occurrence of several common alleles in the general population. This genetically determined variation can affect LTF functions. In this study, we determined the distribution of LTF gene polymorphisms (rs1126477, rs1126478, rs2073495, and rs9110) in the Chinese Han population and investigated whether these polymorphisms were associated with increased risk of ovarian carcinoma in the Chinese. It was found that the rs1126477 was correlated significantly with ovarian cancer. The frequency of A allele of rs1126477 was significantly higher in 700 ovarian cancer patients compared with that in the control group of 700 cases (P< 0.01, χ(2)= 6.79). The frequency of AA genotype was significantly higher in ovarian cancer patients compared with that in the control group (P< 0.05, χ(2)= 6.49). AA genotype is the risk factor of ovarian cancer. The odds ratio (OR) was 2.24 and the 95% confidence interval (CI) was 1.08-4.59, respectively. The 'A-G-C-C' haplotype constructed with rs1126477, rs1126478, rs2073495, and rs9110 was the risk factor to be ovarian cancer. The expression of LTF gene was lower in individuals with 'A-G-C-C' haplotype compared with that in individuals without 'A-G-C-C' haplotype. These findings suggested that rs1126477 could play important roles in ovarian carcinoma physiological processes in the Chinese.

New role of microRNA: carcinogenesis and clinical application in cancer

MicroRNA (miRNA) is a cluster of small non-encoding RNA molecules of 21-23 nucleotides in length, which controls the expression of target gene at the post-transcriptional level. Recent researches have indicated that miRNA plays an essential role in carcinogenesis, such as affecting the cell growth, differentiation, apoptosis, and cell cycle. Nowadays, multiple promising roles of miRNA involved in carcinogenesis are emerging, and it is shown that miRNA closely relates to the process of epithelial-mesenchymal transition (EMT), the regulation of cancer stem cells (CSCs), the development of tumor invasion and migration. miRNA also acts as a biomarker stably expressed in serum and provides new target for molecular target therapy of various cancers. The aim of this review is to illustrate the new role of miRNA in carcinogenesis and highlight the new prospects of miRNA in cancer clinical application, such as in serological diagnosis and molecular-targeted therapeutics.

Alzheimer-specific variants in the 3'UTR of Amyloid precursor protein affect microRNA function

Background

APP expression misregulation can cause genetic Alzheimer's disease (AD). Recent evidences support the hypothesis that polymorphisms located in microRNA (miRNA) target sites could influence the risk of developing neurodegenerative disorders such as Parkinson's disease (PD) and frontotemporal dementia. Recently, a number of single nucleotide polymorphisms (SNPs) located in the 3'UTR of APP have been found in AD patients with family history of dementia. Because miRNAs have previously been implicated in APP expression regulation, we set out to determine whether these polymorphisms could affect miRNA function and therefore APP levels.

Results

Bioinformatics analysis identified twelve putative miRNA bindings sites located in or near the APP 3'UTR variants T117C, A454G and A833C. Among those candidates, seven miRNAs, including miR-20a, miR-17, miR-147, miR-655, miR-323-3p, miR-644, and miR-153 could regulate APP expression in vitro and under physiological conditions in cells. Using luciferase-based assays, we could show that the T117C variant inhibited miR-147 binding, whereas the A454G variant increased miR-20a binding, consequently having opposite effects on APP expression.

Conclusions

Taken together, our results provide proof-of-principle that APP 3'UTR polymorphisms could affect AD risk through modulation of APP expression regulation, and set the stage for further association studies in genetic and sporadic AD.

MiR-886-3p regulates cell proliferation and migration, and is dysregulated in familial non-medullary thyroid cancer

Background

The molecular basis and characteristics of familial non-medullary thyroid cancer are poorly understood. In this study, we performed microRNA (miRNA) profiling of familial and sporadic papillary thyroid cancer tumor samples.

Methodology/Principal Findings

Genome wide miRNA profiling of sporadic and familial papillary thyroid cancer was performed. Differentially expressed miRNAs were validated by quantitative RT-PCR. Ectopic expression of miR-886-3p in thyroid cancer lines was performed to identify pathways targeted by the miRNA, as well as, to determine its effect on tumor cell biology. We found four differentially expressed miRNAs between familial and sporadic papillary thyroid cancer tumor samples. MiR-886-3p and miR-20a were validated to be differentially expressed by 3- and 4-fold, respectively. Pathway analysis of genome-wide expression data on cells overexpressing miR-886-3p and target prediction analysis showed genes involved in DNA replication and focal adhesion pathways were regulated by miR-886-3p. Overexpression of miR-886-3p in thyroid cancer cell lines significantly inhibited cellular proliferation, the number and size of spheroids and cellular migration. Additionally, overexpression of miR-886-3p increased the number of cells in S phase.

Conclusions/Significance

Our findings for the first time suggest that miR-886-3p plays an important role in thyroid cancer tumor cell biology and regulates genes involved in DNA replication and focal adhesion. Thus, miR-886-3p may play a role in the initiation and or progression of papillary thyroid cancer.

MicroRNAs and Alzheimer's Disease Mouse Models: Current Insights and Future Research Avenues

Evidence from clinical trials as well as from studies performed in animal models suggest that both amyloid and tau pathologies function in concert with other factors to cause the severe neurodegeneration and dementia in Alzheimer's disease (AD) patients. Accumulating data in the literature suggest that microRNAs (miRNAs) could be such factors. These conserved, small nonprotein-coding RNAs are essential for neuronal function and survival and have been implicated in the regulation of key genes involved in genetic and sporadic AD. The study of miRNA changes in AD mouse models provides an appealing approach to address the cause-consequence relationship between miRNA dysfunction and AD pathology in humans. Mouse models also provide attractive tools to validate miRNA targets in vivo and provide unique platforms to study the role of specific miRNA-dependent gene pathways in disease. Finally, mouse models may be exploited for miRNA diagnostics in the fight against AD.

MicroRNA-20a overexpression inhibited proliferation and metastasis of pancreatic carcinoma cells

The aim of this study was to investigate the effect of microRNA-20a on pancreatic carcinoma cell proliferation and invasion and to find a new effective treatment strategy for pancreatic carcinoma. MicroRNA-20a expression was determined in 10 matched normal pancreatic tissues and pancreatic carcinoma by in situ hybridization. Quantitative real-time RT-PCR was used to evaluate the expression of microRNA-20a in two pancreatic carcinoma cell lines (BxPC-3 and Panc-1) and immortal human pancreatic duct epithelial cell line H6C7. Proliferation and invasion capacity were analyzed for the cells with lentivirus-mediated overexpression of microRNA-20a both in vitro and in vivo. In addition, the regulation of signal transducer and activator of transcription proteins 3 (Stat3) by microRNA-20a was determined to elucidate the underlying mechanisms. The pancreatic cancer cell lines (Panc-1 and BxPC-3) stably overexpressing microRNA-20a showed reduced proliferation and invasion capacity in vitro and in vivo, compared with parental cells or cells transfected with a control vector. Furthermore, we found that microRNA-20a negatively regulated Stat3 protein expression in a dose-dependent manner without changing the Stat3 mRNA level and decreased the activity of a luciferase reporter construct containing the Stat3 3'-untranslated region. These results show that microRNA-20a regulates Stat3 at the post-transcriptional level, resulting in inhibition of cell proliferation and invasion of pancreatic carcinoma. It may open a new perspective for the development of effective gene therapy for pancreatic carcinoma.

MicroRNA-101 downregulates Alzheimer's amyloid-β precursor protein levels in human cell cultures and is differentially expressed

The full repertoire of regulatory interactions utilized by human cells to control expression of amyloid-β precursor protein (APP) is still undefined. We investigated here the contribution of microRNA (miRNA) to this regulatory network. Several bioinformatic algorithms predicted miR-101 target sites within the APP 3'-untranslated region (3'-UTR). Using reporter assays, we confirmed that, in human cell cultures, miR-101 significantly reduced the expression of a reporter under control of APP 3'-UTR. Mutation of predicted site 1, but not site 2, eliminated this reporter response. Delivery of miR-101 directly to human HeLa cells significantly reduced APP levels and this effect was eliminated by co-transfection with a miR-101 antisense inhibitor. Delivery of a specific target protector designed to blockade the interaction between miR-101 and its functional target site within APP 3'-UTR enhanced APP levels in HeLa. Therefore, endogenous miR-101 regulates expression of APP in human cells via a specific site located within its 3'-UTR. Finally, we demonstrate that, across a series of human cell lines, highest expression of miR-101 levels was observed in model NT2 neurons.

Inhibiting adenoid cystic carcinoma cells growth and metastasis by blocking the expression of ADAM 10 using RNA interference

Background

Adenoid cystic carcinoma is one of the most common types of salivary gland cancers. The poor long-term prognosis for patients with adenoid cystic carcinoma is mainly due to local recurrence and distant metastasis. Disintegrin and metalloprotease 10 (ADAM 10) is a transmembrane protein associated with metastasis in a number of diverse of cancers. The aim of this study was to analyze the relationship between ADAM 10 and the invasive and metastatic potentials as well as the proliferation capability of adenoid cystic carcinoma cells in vitro and in vivo.

Methods

Immunohistochemistry and Western blot analysis were applied to detect ADAM 10 expression levels in metastatic cancer tissues, corresponding primary adenoid cystic carcinoma tissues, adenoid cystic carcinoma cell lines with high metastatic potential, and adenoid cystic carcinoma cell lines with low metastatic potential. RNA interference was used to knockdown ADAM 10 expression in adenoid cystic carcinoma cell lines with high metastatic potential. Furthermore, the invasive and metastatic potentials as well as the proliferation capability of the treated cells were observed in vitro and in vivo.

Results

It was observed that ADAM 10 was expressed at a significantly higher level in metastatic cancer tissues and in adenoid cystic carcinoma cell lines with high metastatic potential than in corresponding primary adenoid cystic carcinomas and adenoid cystic carcinoma cell lines with low metastatic potential. Additionally, silencing of ADAM 10 resulted in inhibition of cell growth and invasion in vitro as well as inhibition of cancer metastasis in an experimental murine model of lung metastases in vivo.

Conclusions

These studies suggested that ADAM 10 plays an important role in regulating proliferation and metastasis of adenoid cystic carcinoma cells. ADAM 10 is potentially an important therapeutic target for the prevention of tumor metastases in adenoid cystic carcinoma.

In vivo regulation of amyloid precursor protein neuronal splicing by microRNAs

The β-amyloid peptide that accumulate in Alzheimer's disease (AD) brain derive from proteolytic processing of the amyloid precursor protein (APP). Recent evidence suggest that microRNAs (miRNAs) participate in the post-transcriptional regulation of APP expression. Because gene dosage effects of the APP gene can cause genetic AD, dysregulation of the miRNA network could contribute significantly to disease. Here, we present evidence that, besides APP expression regulation, miRNAs are equally involved in the regulation of neuronal APP mRNA alternative splicing. Lack of miRNAs in post-mitotic neurons in vivo is associated with APP exons 7 and 8 inclusion, while ectopic expression of miR-124, an abundant neuronal-specific miRNA, reversed these effects in cultured neurons. Similar results were obtained by depletion of endogenous polypyrimidine tract binding protein 1 (PTBP1) in cells, a recognized miR-124 target gene. Furthermore, PTBP1 levels correlate with the presence of APP exons 7 and 8, while PTBP2 levels correlate with the skipping of these exons during neuronal differentiation. Finally, we show that miR-124 is down-regulated in AD brain. In sum, our results suggest that specific miRNAs are involved in the fine-tuning of APP alternative splicing in neurons. Since abnormal neuronal splicing of APP affects β-amyloid peptide production, these results could contribute to the understanding of the implication of miRNAs in brain health and disease.