miR-93, miR-98, and miR-197 regulate expression of tumor suppressor gene FUS1

The oncomiR miR-197 is a novel prognostic indicator for non-small cell lung cancer patients

Background:

MicroRNA expression signatures can promote personalised care for non-small cell lung cancer (NSCLC) patients. Our aim was to evaluate the previously unexplored prognostic potential of miR-197, a key oncogenic molecule for NSCLC.

Methods:

Total RNA isolation (n=124 NSCLC and n=21 tumour-adjacent normal tissues), was performed using the QIAsymphony SP workstation. The quantity and quality of RNA were assessed by spectrophotometric analysis and an Agilent 2100 bioanalyzer. Polyadenylation and reverse transcription were subsequently carried out. MiR-197 expression levels were measured by qPCR, after quality control (inter-assay CV=7.8%). Internal validation procedures were followed by assigning training and test sets and robust biostatistical analyses were performed, including bootstrap resampling.

Results:

MiR-197 is associated with larger tumours (P=0.042) and the squamous cell carcinoma histotype (P=0.032). Interestingly, after adjusting for important prognostic indicators, miR-197 expression was identified as a novel independent predictor of unfavourable prognosis for NSCLC patients (HR=1.97, 95% CI=1.10–3.38, P=0.013). We also demonstrate that miR-197 retains its prognostic performance in both early-stage I (P=0.045) and more advanced-stage individuals (P=0.036).

Conclusions:

The cost-effective expression analysis of miR-197 could constitute a novel molecular tool for NSCLC management.

microRNA-548l is involved in the migration and invasion of non-small cell lung cancer by targeting the AKT1 signaling pathway

PURPOSE

microRNAs (miRNAs) have been documented playing a critical role in cancer development and progression. In this study, we investigated the role of miR-548l in non-small cell lung cancer (NSCLC) migration and invasion.

METHODS

microRNAs microarray analysis was used to detect the differentially expressed miRNAs between various metastatic levels of NSCLC cells and further confirmed by real-time PCR analysis. To facilitate the delineation of the role of selected miR-548l in NSCLC pathology, we detected its expression in 22 NSCLC tissues. Proliferation, apoptosis, invasion and metastasis effects of the miRNA were evaluated using MTT, flow cytometry, wound healing and invasion assay following transfection with mimics and inhibitors. Luciferase assay and Western blot analysis were performed to assess miR-548l binding to AKT1 gene. AKT1 expression in the clinical tissues was evaluated using immunohistochemical staining.

RESULTS

The results showed a negative relationship between miR-548l expression and lymph node metastasis of NSCLC. Functional assays showed that over-expression of miR-548l suppressed NSCLC cell migration and invasion. Luciferase assays confirmed that miR-548l could directly bind to the 3' untranslated region of AKT1. Further data showed that the over-expression of AKT1 could rescue the effects of miR-548l in NSCLC cells, and the miR-548l expression was inversely correlated with AKT1 expression in NSCLC tissues. These results indicated that AKT1 was involved in miR-548l-induced suppression of NSCLC cell migration and invasion.

CONCLUSION

These results suggested that miR-548l may play a causal role through AKT1 in NSCLC invasion and metastasis.

A high-content morphological screen identifies novel microRNAs that regulate neuroblastoma cell differentiation

Neuroblastoma, the most common extracranial solid tumor of childhood, arises from neural crest cell precursors that fail to differentiate. Inducing cell differentiation is an important therapeutic strategy for neuroblastoma. We developed a direct functional high-content screen to identify differentiation-inducing microRNAs, in order to develop microRNA-based differentiation therapy for neuroblastoma. We discovered novel microRNAs, and more strikingly, three microRNA seed families that induce neuroblastoma cell differentiation. In addition, we showed that microRNA seed families were overrepresented in the identified group of fourteen differentiation-inducing microRNAs, suggesting that microRNA seed families are functionally more important in neuroblastoma differentiation than microRNAs with unique sequences. We further investigated the differentiation-inducing function of the microRNA-506-3p/microRNA-124-3p seed family, which was the most potent inducer of differentiation. We showed that the differentiation-inducing function of microRNA-506-3p/microRNA-124-3p is mediated, at least partially, by down-regulating expression of their targets CDK4 and STAT3. We further showed that expression of miR-506-3p, but not miR-124-3p, is dramatically upregulated in differentiated neuroblastoma cells, suggesting the important role of endogenous miR-506-3p in differentiation and tumorigenesis. Overall, our functional screen on microRNAs provided the first comprehensive analysis on the involvements of microRNA species in neuroblastoma cell differentiation and identified novel differentiation-inducing microRNAs. Further investigations are certainly warranted to fully characterize the function of the identified microRNAs in order to eventually benefit neuroblastoma therapy.

Effects of miRNA-197 overexpression on proliferation, apoptosis and migration in levonorgestrel treated uterine leiomyoma cells

BACKGROUND/AIMS

Uterine leiomyoma is the ahead benign tumor of the female genital tract, which resulted in menstrual abnormalities, recurrent pregnancy loss, and other serious gynecological disorders in women. Recently, as the process of exploring the brief molecular mechanisms of tumorgenesis, microRNAs (miRNAs) have attracted much more attention.

METHODS

In this study, we first confirmed that microRNA-197 (miR-197) was down-regulated significantly in human uterus leiomyoma by quantity real-time polymerase chain reaction, compared to normal uterus myometrium. Then we observed the potential effects of miR-197 overexpression on human uterus leiomyoma cells by cell counting kit 8, wound healing assay, and flow cytometric assessment separately.

RESULTS

The data showed that miR-197 could inhibit cell proliferation, induce cell apoptosis, and block cell migration in vitro. Coincidently, levonorgestrel (LNG), a well-known uterus leiomyoma therapy, could induce miR-197 expression in human uterus leiomyoma cells, and over-expression of miR-197 showed a synergy effect on human uterus leiomyoma cell proliferation and apoptosis with LNG.

CONCLUSION

In this study, the data showed that miR-197 could play an anti-oncogenic role in human uterus leiomyoma cells, and cooperate with LNG on the cell proliferation and apoptosis, which suggested that miR-197 might be a potential target and provided database for clinical treatment.

Role of microRNAs -29b-2, -155, -197 and -205 as diagnostic biomarkers in serum of breast cancer females

Micro-RNAs (miRs) are known to be differentially expressed in the serum of cancer patients and controls, and can thus be used as biomarkers for cancer screening. We detected the expression level of miR-29b-2, 155, 197 and 205 in the serum of female breast cancer patients and healthy controls to detect whether serum level of this chosen micro-RNAs could detect patients with breast cancer and also to detect difference in level of micro-RNAs between non-metastatic cases and metastatic cases, also we tried to detect any relation between level of micro-RNAs and the stage of the tumor, the size of tumor, nodal affection, the presence of metastasis and also the site of metastasis. Serum samples were collected from 130 female patients, 80 with non-metastatic breast cancer, 20 with metastatic breast cancer and 30 healthy controls. Real-time quantitative PCR was used to detect the expression level of miR-29b-2, -155, -197 and -205. The expression level of miR-29b-2, -155, -197 and -205 was significantly increased in the serum of breast cancer patients. miR-29b-2, -155, -197 and -205 may be useful as a blood-based biomarker for breast cancer screening.

The clinical relevance of the miR-197/CKS1B/STAT3-mediated PD-L1 network in chemoresistant non-small-cell lung cancer

Programmed cell death ligand-1 (PD-L1) has recently gained considerable attention for its role in tumor immune escape. Here, we identify a miR-197/CKS1B/STAT3-mediated PD-L1 network in chemoresistant non-small-cell lung cancer (NSCLC), independent of immunoinhibitory signals. miR-197 is downregulated in platinum-resistant NSCLC specimens, resulting in the promotion of chemoresistance, tumorigenicity, and pulmonary metastasis in vitro and in vivo. Mechanistic investigations reveal that a miR-197-mediated CKS1B/STAT3 axis exerts tumor progression regulated by various oncogenic genes (Bcl-2, c-Myc, and cyclin D1), and PD-L1 is a putative biomarker of this axis. Furthermore, we demonstrate that a miR-197 mimic sensitizes PD-L1^high drug-resistant cells to chemotherapy. These results indicate that the biological interaction between PD-L1 and chemoresistance occurs through the microRNA regulatory cascade. More importantly, expression levels of miR-197 are inversely correlated with PD-L1 expression (n = 177; P = 0.026) and are associated with worse overall survival (P = 0.015). Our discoveries suggest that the miR-197/CKS1B/STAT3-mediated network can drive tumor PD-L1 expression as a biomarker of this cascade, and miR-197 replacement therapy may be a potential treatment strategy for chemoresistant NSCLC.

Increased expression of miR-93 is associated with poor prognosis in head and neck squamous cell carcinoma

MicroRNA-93-5p (miR-93) is a novel oncogenic microRNA (miRNA) and is elevated in diverse human malignancies. Aberrant expression and dysfunction of miR-93 are involved in many types of human tumours. However, the exact role of miR-93 remains unclear in head and neck squamous cell carcinoma (HNSCC). The objective of this study is to determine the expression pattern and clinical significance of miR-93 in HNSCC. MiR-93 expression levels in 103 primary HNSCC tissues and 16 corresponding non-cancerous epithelia were analysed by miRNA in situ hybridisation and correlated with the clinicopathological parameters and patient outcomes. Moreover, the expression of miR-93 was examined in four HNSCC cell lines and 17 pairs of HNSCC tissues and their corresponding adjacent tissues using quantitative real-time PCR (qRT-PCR). The miR-93 levels in HNSCC tissues and cell lines were significantly higher than those in the non-cancerous tissues. Notably, high miR-93 expression was significantly associated with T classification, lymph node metastasis and clinical stage. Kaplan-Meier survival analysis demonstrated that patients with high miR-93 expression had poorer overall survival than patients with low miR-93 expression. Multivariate Cox regression analysis revealed that miR-93 overexpression and lymph node metastasis were independent prognostic factors in patients with HNSCC. This study demonstrated that miR-93 expression was significantly increased in HNSCC tissue samples and cell lines and that miR-93 overexpression was associated with tumour progression, metastasis and poor prognosis in HNSCC patients. These results suggest that miR-93 may play a critical role in the initiation and progression of HNSCC, indicating that miR-93 may be a valuable marker for the prediction of metastasis and prognosis in HNSCC.

MicroRNA-223 Expression is Upregulated in Insulin Resistant Human Adipose Tissue

MicroRNAs (miRNAs) are short noncoding RNAs involved in posttranscriptional regulation of gene expression and influence many cellular functions including glucose and lipid metabolism. We previously reported that adipose tissue (AT) from women with polycystic ovary syndrome (PCOS) or controls with insulin resistance (IR) revealed a differentially expressed microRNA (miRNA) profile, including upregulated miR-93 in PCOS patients and in non-PCOS women with IR. Overexpressed miR-93 directly inhibited glucose transporter isoform 4 (GLUT4) expression, thereby influencing glucose metabolism. We have now studied the role of miR-223, which is also abnormally expressed in the AT of IR subjects. Our data indicates that miR-223 is significantly overexpressed in the AT of IR women, regardless of whether they had PCOS or not. miR-223 expression in AT was positively correlated with HOMA-IR. Unlike what is reported in cardiomyocytes, overexpression of miR-223 in human differentiated adipocytes was associated with a reduction in GLUT4 protein content and insulin-stimulated glucose uptake. In addition, our data suggests miR-223 regulates GLUT4 expression by direct binding to its 3' untranslated region (3'UTR). In conclusion, in AT miR-223 is an IR-related miRNA that may serve as a potential therapeutic target for the treatment of IR-related disorders.

Mir-660 is downregulated in lung cancer patients and its replacement inhibits lung tumorigenesis by targeting MDM2-p53 interaction

Lung cancer represents the leading cause of cancer-related death in developed countries. Despite the advances in diagnostic and therapeutic techniques, the 5-year survival rate remains low. The research for novel therapies directed to biological targets has modified the therapeutic approach, but the frequent engagement of resistance mechanisms and the substantial costs, limit the ability to reduce lung cancer mortality. MicroRNAs (miRNAs) are small noncoding RNAs with known regulatory functions in cancer initiation and progression. In this study we found that mir-660 expression is downregulated in lung tumors compared with adjacent normal tissues and in plasma samples of lung cancer patients with poor prognosis, suggesting a potential functional role of this miRNA in lung tumorigenesis. Transient and stable overexpression of mir-660 using miRNA mimics reduced migration, invasion, and proliferation properties and increased apoptosis in p53 wild-type lung cancer cells (NCI-H460, LT73, and A549). Furthermore, stable overexpression using lentiviral vectors in NCI-H460 and A549 cells inhibited tumor xenograft growth in immunodeficient mice (95 and 50% reduction compared with control, respectively), whereas the effects of mir-660 overexpression were absent in H1299, a lung cancer cell line lacking p53 locus, both in in vitro and in vivo assays. We identified and validated mouse double minute 2 (MDM2) gene, a key regulator of the expression and function of p53, as a new direct target of mir-660. In addition, mir-660 expression reduced both mRNA and protein expression of MDM2 in all cell lines and stabilized p53 protein levels resulting in an upregulation of p21^WAF1/CIP1 in p53 wild-type cells. Our finding supports that mir-660 acts as a tumor suppressor miRNA and we suggest the replacement of mir-660 as a new therapeutic approach for p53 wild-type lung cancer treatment.

Non-coding RNAs in lung cancer

The discovery that protein-coding genes represent less than 2% of all human genome, and the evidence that more than 90% of it is actively transcribed, changed the classical point of view of the central dogma of molecular biology, which was always based on the assumption that RNA functions mainly as an intermediate bridge between DNA sequences and protein synthesis machinery. Accumulating data indicates that non-coding RNAs are involved in different physiological processes, providing for the maintenance of cellular homeostasis. They are important regulators of gene expression, cellular differentiation, proliferation, migration, apoptosis, and stem cell maintenance. Alterations and disruptions of their expression or activity have increasingly been associated with pathological changes of cancer cells, this evidence and the prospect of using these molecules as diagnostic markers and therapeutic targets, make currently non-coding RNAs among the most relevant molecules in cancer research. In this paper we will provide an overview of non-coding RNA function and disruption in lung cancer biology, also focusing on their potential as diagnostic, prognostic and predictive biomarkers.

STAT6 silencing up-regulates cholesterol synthesis via miR-197/FOXJ2 axis and induces ER stress-mediated apoptosis in lung cancer cells

MiRNAs and transcription factors have emerged as important regulators for gene expression and are known to regulate various biological processes, including cell proliferation, differentiation and apoptosis. Previously, using genome-wide expression profiling studies, we have shown an inverse relationship of STAT6 and cholesterol biosynthesis and also identified FOXJ2 binding sites in the upstream region of 3 key genes (HMGCR, HMGCS1 and IDI1) of the cholesterol synthesis pathway. Our previous study also provided clues toward the anti-apoptotic role played by STAT6. For better understanding of the cellular response and underlying signaling pathways activated by STAT6 silencing, we examined the changes in miRNome profile after the siRNA-mediated silencing of STAT6 gene in NCI-H460 cells using LNA-based miRNA microarray. Our analysis showed significant downregulation of miRNAs, let-7b and miR-197, out of which miR-197 was predicted to target FOXJ2. We here show that miR-197 not only negatively regulates FOXJ2 expression through direct binding to its respective binding site in its 3'UTR but also alters total cholesterol levels by regulating genes associated with cholesterol biosynthesis pathway. We further demonstrated that STAT6 silencing elicited ER stress-mediated apoptosis in NCI-H460 cells through C/EBP homologous protein (CHOP) induction, alteration of BH3 only proteins expression and ROS production. The apoptosis induced by STAT6 downregulation was partially reversed by NAC, the ROS scavenger. Based on the above findings, we suggest that ER stress plays a major role in STAT6-induced apoptosis.

MicroRNA-93 regulates cyclin G2 expression and plays an oncogenic role in laryngeal squamous cell carcinoma

microRNA93 (miR-93) is expressed in the miR‑106b-25 cluster, located in intron 13 of the MCM7 gene. Our previous study found that miR-93 was significantly upregulated in laryngeal squamous cell carcinoma (LSCC), and cyclin G2 (CCNG2) was a potential target of miR-93 in LSCC. However, the possible functions and molecular mechanisms of miR-93 in LSCC remain unknown. In the present study, we show that the level of CCNG2 protein expression was significantly lower in LSCC cancer tissue than normal tissues. The level of CCNG2 was correlated with clinical stages, lymph node metastasis and histological grade. We further show that the expression level of miR-93 was inversely correlated with CCNG2 expression in clinical specimens. Furthermore, gain-of-function assays revealed that miR-93 promoted cell proliferation, decreased apoptosis rates, induced cell cycle arrest and promoted cell migration and invasion, whereas silencing of miR-93 attenuated these carcinogenic processes. In addition, overexpression of miR-93 in Hep-2 cells could reduce the mRNA and protein levels of CCNG2, whereas silencing of miR-93 in Hep-2 cells significantly increased CCNG2 expression. A luciferase assay verified that miR-93 could bind to the 3' untranslated region of CCNG2. Importantly, ectopic expression of CCNG2 in miR-93 cells rescued the effect of miR-93 on LSCC proliferation. Knockdown of CCNG2 promoted cell proliferation resembling that of miR-93 overexpression. These findings demonstrated that miR-93 promotes tumor growth by directly suppressing CCNG2. Taken together, these results suggested that this newly identified miR-93-CCNG2 axis may be involved in LSCC proliferation and progression. Our findings provide novel potential targets for LSCC therapy and prognosis.

Therapeutic use of microRNAs in lung cancer

Lung cancer is a leading cause of cancer deaths worldwide. Although the molecular pathways of lung cancer have been partly known, the high mortality rate is not markedly changed. MicroRNAs (miRNAs) are small noncoding RNAs that actively modulate cell physiological processes as apoptosis, cell-cycle control, cell proliferation, DNA repair, and metabolism. Several studies demonstrated that miRNAs are involved in the pathogenesis of lung diseases including lung cancer and they negatively regulate gene and protein expression by acting as oncogenes or tumor suppressors. In this review we summarize the current knowledge on the role of miRNAs and their target genes in lung tumorigenesis and evaluate their potential use as therapeutic agents in lung cancer. In particular, we describe methodological approaches such as inhibition of oncogenic miRNAs or replacement of tumor suppressor miRNAs, both in in vitro and in vivo assays. Furthermore we discuss new strategies to achieve in vivo tissue specific delivery, potential off-target effects, and safety of miRNAs systemic delivery.

Role of microRNA-93 in regulation of angiogenesis

Angiogenesis is essential for a wide variety of physiological and pathological processes. To date, many angiogenic microRNAs (miRNAs) have been identified and several of them were further investigated to elucidate the mechanisms of specific miRNAs in regulating angiogenesis. In recent studies concerning tumor and ischemia, the miRNA-93 had been demonstrated to be able to modulate angiogenesis in different molecular pathways. The miRNA-93 can promote angiogenesis via enhancing endothelial cell proliferation, migration, and tube formation. Additionally, miRNA-93-over-expressing cells developed a relationship with the blood vessels allowing tumor cells to survive and to grow well. However, high expression of miRNA-93 can depress the vascular endothelial growth factor (VEGF) secretion and its downstream molecular targets in in vivo and vitro experiments. MiRNA-93's effects on angiogenesis are dependent on the interaction of other multiple genes and signal pathways, such as P21, E2F1, integrin-β8, LATS2, etc. Future investigation should involve mapping the network by which miRNA-93 exerts its functions.

MicroRNA expression profile of bromocriptine-resistant prolactinomas

MicroRNAs (miRNA) have been implicated in the resistance of tumors to chemotherapy. However, little is known about miRNA expression in bromocriptine-resistant prolactinomas. In this study, 23 prolactinoma samples were classified as bromocriptine-sensitive or -resistant according to the clinical definition of bromocriptine resistance, and their miRNA expression profiles were determined using Solexa sequencing. We found 41 miRNAs that were differentially expressed between the two groups, and 12 of these were validated by stem-loop qRT-PCR. Hsa-mir-93, hsa-mir-17, hsa-mir-22*, hsa-mir-126*, hsa-mir-142-3p, hsa-mir-144*, hsa-mir-486-5p, hsa-mir-451, and hsa-mir-92a were up-regulated and hsa-mir-30a, hsa-mir-382, and hsa-mir-136 were down-regulated in bromocriptine-resistant prolactinomas in comparison with bromocriptine-sensitive prolactinomas. Furthermore, silencing of mir-93 significantly increased the sensitivity of MMQ cells to dopamine agonist treatment. Mir-93 directly affected p21 expression in MMQ cells by targeting the 3'-UTR. Our study is the first to identify a miRNA expression profile associated with bromocriptine-resistant prolactinoma.

Preliminary analysis of different microRNA expression levels in juvenile angiofibromas

Juvenile angiofibroma (JA) is a rare fibrovascular tumor affecting, almost exclusively, adolescent males. The finding of frequent β-catenin-mutations in JAs emphasized the significance of the Wnt-signaling pathway in tumor pathogenesis. In the last decade, microRNAs (miRNAs or miRs) have been found to be involved in cancer pathogenesis by post-transcriptional regulation of gene expression and have not been analyzed in JAs thus far. In the present study, the expression of 4 miRNAs (hsa-let-7d, hsa-miR-98, hsa-miR-125a-5p and hsa-miR-218) was analyzed in 13 JAs and 3 deepithelized inferior nasal turbinates that were used as control tissue. The miRNA expression of hsa-let-7d (P=0.158) and hsa-miR-98 (P=0.069) was not statistically different between the two tissue types, however, a significant decrease in expression was observed for hsa-miR-125a-5p (P=0.037) and hsa-miR-218 (P=0.009) in JAs compared to inferior nasal turbinates. As downregulation of miRNA 218 has been recently shown to result in stabilization and nuclear accumulation of β-catenin, the present data indicates further evidence for the importance of the Wnt-signaling pathway in JAs.

An NTD-associated polymorphism in the 3' UTR of MTHFD1L can affect disease risk by altering miRNA binding

Maternal folate levels and polymorphisms in folate-related genes are known risk factors for neural tube defects (NTDs). SNPs in the mitochondrial folate gene MTHFD1L are associated with the risk of NTDs. We investigated whether different alleles of SNP rs7646 in the 3' UTR of MTHFD1L can be differentially regulated by microRNAs affecting MTHFD1L expression. We previously reported that miR-9 targets MTHFD1L and now we identify miR-197 as an additional miRNA regulator. Both of these miRNAs have predicted binding sites in the MTHFD1L 3' UTR in the region containing SNP rs7646. We have determined whether the alleles of SNP rs7646 (A/G) and miRNA expression levels affect miRNA binding preferences for the MTHFD1L 3' UTR and consequently MTHFD1L expression. Our results indicate that miR-9 and miR-197 specifically downregulate MTHFD1L levels in HEK293 and MCF-7 cells and that SNPrs7646 significantly affects miR-197 binding affinity to the MTHFD1L 3' UTR, causing more efficient posttranscriptional gene repression in the presence of the allele that is associated with increased risk of NTDs. These results reveal that the association of SNP rs7646 and NTD risk involves differences in microRNA regulation and, highlights the importance of genotype-dependent differential microRNA regulation in relation to human disease risk.

The potential clinical applications and prospects of microRNAs in lung cancer

Lung cancer is the major cause of cancer deaths worldwide due to its late diagnosis and poor outcome. Understanding genomic medicine may widen our vision into the oncogenesis of lung cancer and may open the door to improvements in the clinical management of lung cancer. It is well known that almost half of all genes are regulated by microRNAs (miRNAs). This review focuses on the role of miRNAs in lung cancer and also touches on the value of miRNA-based novel therapies for lung cancers.

Screening of differentially expressed microRNA in ulcerative colitis related colorectal cancer

OBJECTIVE

To investigate the differential expression of microRNA (miRNA) in colon between ulcerative colitis (UC) and ulcerative colitis related colorectal cancer (UCRCC).

METHODS

An UC mouse model was built by dextran sodium sulfate, and an UCRCC mouse model by dextran sodium sulfate and 1,2-diformylhydrazine. RNAs were extracted from the colon, purified and hybridized with fluorescence-labeled miRNA oligonucleotide gene chip. Real-time fluorescence quantitative PCR was used to verify the expression variation of miRNA. SAM was employed for the data analysis.

RESULTS

The up-regulated miRNAs in colon cancer included has-miR-194, has-miR-215, has-miR-93, has-miR-192, has-miR-92a, has-miR-29b, and has-miR-20a (median false discovery rate<5%), while the down-regulated miRNAs were has-miR-1231, has-miR-195, has-miR-143, and has-miR-145 (median false discovery rate<5%).

CONCLUSIONS

Significant differential expression of miRNA was found between the UC mouse and UCRCC mouse, which may be related to the onset, erosion and transfer of colorectal cancer.

Anti-miR-197 inhibits migration in HCC cells by targeting KAI 1/CD82

AIM

To investigate the metastatic effects and mechanisms of miR-197 in hepatocellular carcinoma (HCC).

METHODS AND RESULTS

The levels of miR-197 increased in HCC cells and tissues compared with a normal hepatic cell line (LO2) and adjacent nontumorous liver tissues, respectively. miR-197 expression negatively correlated with CD82 mRNA expression in these cell lines and tissues. Dual luciferase reporter assay and Western blot confirmed a direct interaction between miR-197 and CD82 3'UTR sequences. After miR-197 was silenced in HCC cells, CD82 expression increased. In the presence of human hepatocyte growth factor (HGF), cells silenced for anti-miR-197 exhibited elongated cellular tails and diminished lamellipodia due to reductions in both ROCK activity and the levels of Rac 1 protein. Downregulation of miR-197 along with the upregulation of CD82 in HCC cells resulted in the inhibition of HCC migration and invasion in vitro and in vivo.

CONCLUSION

Taken together, these data suggest that anti-miR-197 suppresses HCC migration and invasion by targeting CD82. The regulation of the miR-197/CD82 axis could be a novel therapeutic target in future HCC effective therapy.

MiR-182 is up-regulated and targeting Cebpa in hepatocellular carcinoma

MicroRNAs (miRNAs) are endogenous small non-coding RNAs that repress their targets at post transcriptional level. Existing studies have shown that miRNAs are important regulatory genes in hepatocellular carcinoma (HCC), as either tumor suppressors or oncogenes. MiR-122 is normally downregulated in HCC and regarded as a tumor suppressor. Recently miR-122 has been reported to be regulated by CEBPA, which is then involved in a novel pathway to influence proliferation of tumor cells. However it is unknown whether CEBPA is regulated by miRNAs in HCC. In this study, we find that miR-182 is upregulated in HCC model rat, and represses CEBPA in both rat and human. This further improves the current CEBPA/miR-122 pathway that controls the proliferation of tumor cells. These results suggest that miR-182 is a potential oncogene in HCC and could be used as a diagnostic marker and drug target of HCC.

Identification of candidate miRNA biomarkers from miRNA regulatory network with application to prostate cancer

Background

MicroRNAs (miRNAs) are a class of non-coding regulatory RNAs approximately 22 nucleotides in length that play a role in a wide range of biological processes. Abnormal miRNA function has been implicated in various human cancers including prostate cancer (PCa). Altered miRNA expression may serve as a biomarker for cancer diagnosis and treatment. However, limited data are available on the role of cancer-specific miRNAs. Integrative computational bioinformatics approaches are effective for the detection of potential outlier miRNAs in cancer.

Methods

The human miRNA-mRNA target network was reconstructed by integrating multiple miRNA-mRNA interaction datasets. Paired miRNA and mRNA expression profiling data in PCa versus benign prostate tissue samples were used as another source of information. These datasets were analyzed with an integrated bioinformatics framework to identify potential PCa miRNA signatures. In vitro q-PCR experiments and further systematic analysis were used to validate these prediction results.

Results

Using this bioinformatics framework, we identified 39 miRNAs as potential PCa miRNA signatures. Among these miRNAs, 20 had previously been identified as PCa aberrant miRNAs by low-throughput methods, and 16 were shown to be deregulated in other cancers. In vitro q-PCR experiments verified the accuracy of these predictions. miR-648 was identified as a novel candidate PCa miRNA biomarker. Further functional and pathway enrichment analysis confirmed the association of the identified miRNAs with PCa progression.

Conclusions

Our analysis revealed the scale-free features of the human miRNA-mRNA interaction network and showed the distinctive topological features of existing cancer miRNA biomarkers from previously published studies. A novel cancer miRNA biomarker prediction framework was designed based on these observations and applied to prostate cancer study. This method could be applied for miRNA biomarker prediction in other cancers.

TGFβR2 is a major target of miR-93 in nasopharyngeal carcinoma aggressiveness

Background

MiR-17-92 cluster and its paralogues have emerged as crucial regulators of many oncogenes and tumor suppressors. Transforming growth factor-β receptor II (TGFβR2), as an important tumor suppressor, is involved in various cancer types. However, it is in cancer that only two miRNAs of this cluster and its paralogues have been reported so far to regulate TGFβR2. MiR-93 is oncogenic, but its targetome in cancer has not been fully defined. The role of miR-93 in nasopharyngeal carcinoma (NPC) still remains largely unknown.

Methods

We firstly evaluated the clinical signature of TGFβR2 down-regulation in clinical samples, and next used a miRNA expression profiling analysis followed by multi-validations, including Luciferase reporter assay, to identify miRNAs targeting TGFβR2 in NPC. In vitro and in vivo studies were performed to further investigate the effects of miRNA-mediated TGFβR2 down-regulation on NPC aggressiveness. Finally, mechanism studies were conducted to explore the associated pathway and genes influenced by this miRNA-mediated TGFβR2 down-regulation.

Results

TGFβR2 was down-regulated in more than 50% of NPC patients. It is an unfavorable prognosis factor contributing to clinical NPC aggressiveness. A cluster set of 4 TGFβR2-associated miRNAs was identified; they are all from miR-17-92 cluster and its paralogues, of which miR-93 was one of the most significant miRNAs, directly targeting TGFβR2, promoting cell proliferation, invasion and metastasis in vitro and in vivo. Moreover, miR-93 resulted in the attenuation of Smad-dependent TGF-β signaling and the activation of PI3K/Akt pathway by suppressing TGFβR2, further promoting NPC cell uncontrolled growth, invasion, metastasis and EMT-like process. Impressively, the knockdown of TGFβR2 by siRNA displayed a consentaneous phenocopy with the effect of miR-93 in NPC cells, supporting TGFβR2 is a major target of miR-93. Our findings were also substantiated by investigation of the clinical signatures of miR-93 and TGFβR2 in NPC.

Conclusion

The present study reports an involvement of miR-93-mediated TGFβR2 down-regulation in NPC aggressiveness, thus giving extended insights into molecular mechanisms underlying cancer aggressiveness. Approaches aimed at blocking miR-93 may serve as a promising therapeutic strategy for treating NPC patients.

Antitumor effect of miR-197 targeting in p53 wild-type lung cancer

Lung cancer is the leading cause of tumor-related death. The lack of effective treatments urges the development of new therapeutic approaches able to selectively kill cancer cells. The connection between aberrant microRNA (miRNA - miR) expression and tumor progression suggests a new strategy to fight cancer by interfering with miRNA function. In this regard, LNAs (locked nucleic acids) have proven to be very promising candidates for miRNA neutralization. Here, we employed an LNA-based anti-miR library in a functional screening to identify putative oncogenic miRNAs in non-small-cell lung cancer (NSCLC). By screening NIH-H460 and A549 cells, miR-197 was identified as a new functional oncomiR, whose downregulation induces p53-dependent lung cancer cell apoptosis and impairs the capacity to establish tumor xenografts in immunodeficient mice. We further identified the two BH3-only proteins NOXA and BMF as new miR-197 targets responsible for induction of apoptosis in p53 wild-type cells, delineating miR-197 as a key survival factor in NSCLC. Thus, we propose the inhibition of miR-197 as a novel therapeutic approach against lung cancer.

Small RNA analysis in Sindbis virus infected human HEK293 cells

INTRODUCTION

In contrast to the defence mechanism of RNA interference (RNAi) in plants and invertebrates, its role in the innate response to virus infection of mammals is a matter of debate. Since RNAi has a well-established role in controlling infection of the alphavirus Sindbis virus (SINV) in insects, we have used this virus to investigate the role of RNAi in SINV infection of human cells.

RESULTS

SINV AR339 and TR339-GFP were adapted to grow in HEK293 cells. Deep sequencing of small RNAs (sRNAs) early in SINV infection (4 and 6 hpi) showed low abundance (0.8%) of viral sRNAs (vsRNAs), with no size, sequence or location specific patterns characteristic of Dicer products nor did they possess any discernible pattern to ascribe to a specific RNAi biogenesis pathway. This was supported by multiple variants for each sequence, and lack of hot spots along the viral genome sequence. The abundance of the best defined vsRNAs was below the limit of Northern blot detection. The adaptation of the virus to HEK293 cells showed little sequence changes compared to the reference; however, a SNP in E1 gene with a preference from G to C was found. Deep sequencing results showed little variation of expression of cellular microRNAs (miRNAs) at 4 and 6 hpi compared to uninfected cells. Twelve miRNAs exhibiting some minor differential expression by sequencing, showed no difference in expression by Northern blot analysis.

CONCLUSIONS

We show that, unlike SINV infection of invertebrates, generation of Dicer-dependent svRNAs and change in expression of cellular miRNAs were not detected as part of the Human response to SINV.

Overexpression of miR-196b and HOXA10 characterize a poor-prognosis gastric cancer subtype

AIM: To identify molecular biologic differences between two gastric adenocarcinoma subgroups presenting different prognoses through the analysis of microRNA and protein expression.

METHODS: Array technologies were used to generate 1146 microRNAs and 124 proteins expression profiles of samples from 60 patients with gastric cancer. For the integrative analysis, we used established mRNA expression data published in our previous study. Whole mRNA expression levels were acquired from microarray data for 60 identical gastric cancer patients. Two gastric adenocarcinoma subgroups with distinct mRNA expression profiles presented distinctly different prognoses. MicroRNA and protein expression patterns were compared between gastric cancer tissue and normal gastric tissue and between two different prognostic groups. Aberrantly expressed microRNA, associated mRNA, and protein in patients with poor-prognosis gastric cancer were validated by quantitative reverse transcription polymerase chain reaction and immunochemistry in independent patients.

RESULTS: We obtained the expression data of 1146 microRNAs and 124 cancer-related proteins. Four microRNAs were aberrantly expressed in the two prognostic groups and in cancer vs non-cancer tissues (P < 0.05). In the poor-prognosis group, miR-196b, miR-135b, and miR-93 were up-regulated and miR-29c* was down-regulated. miR-196b expression positively correlated with Homeobox A10 (HOXA10) expression (r = 0.726, P < 0.001), which was significantly increased in poor-prognosis patients (P < 0.001). Comparing gastric cancer with non-cancer tissues, 46/124 proteins showed differential expression (P < 0.05); COX2 (P < 0.001) and cyclin B1 (P = 0.017) were clearly over-expressed in the poor-prognosis group.

CONCLUSION: Co-activation of miR-196b and HOXA10 characterized a poor-prognosis subgroup of patients with gastric cancer. Elucidation of the biologic function of miR-196b and HOXA10 is warranted.

MicroRNAs as novel regulators of stem cell fate

Mounting evidence in stem cell biology has shown that microRNAs (miRNAs) play a crucial role in cell fate specification, including stem cell self-renewal, lineage-specific differentiation, and somatic cell reprogramming. These functions are tightly regulated by specific gene expression patterns that involve miRNAs and transcription factors. To maintain stem cell pluripotency, specific miRNAs suppress transcription factors that promote differentiation, whereas to initiate differentiation, lineage-specific miRNAs are upregulated via the inhibition of transcription factors that promote self-renewal. Small molecules can be used in a similar manner as natural miRNAs, and a number of natural and synthetic small molecules have been isolated and developed to regulate stem cell fate. Using miRNAs as novel regulators of stem cell fate will provide insight into stem cell biology and aid in understanding the molecular mechanisms and crosstalk between miRNAs and stem cells. Ultimately, advances in the regulation of stem cell fate will contribute to the development of effective medical therapies for tissue repair and regeneration. This review summarizes the current insights into stem cell fate determination by miRNAs with a focus on stem cell self-renewal, differentiation, and reprogramming. Small molecules that control stem cell fate are also highlighted.

Understanding cooperativity of microRNAs via microRNA association networks

Background

MicroRNAs (miRNAs) are key components in post-transcriptional gene regulation in multicellular organisms. As they control cooperatively a large number of their target genes, they affect the complexity of gene regulation. One of the challenges to understand miRNA-mediated regulation is to identify co-regulating miRNAs that simultaneously regulate their target genes in a network perspective.

Results

We created miRNA association network by using miRNAs sharing target genes based on sequence complementarity and co-expression patterns of miRNA-target pairs. The degree of association between miRNAs can be assessed by the level of concordance between targets of miRNAs. Cooperatively regulating miRNAs have been identified by network topology-based approach. Cooperativity of miRNAs is evaluated by their shared transcription factors and functional coherence of target genes. Pathway enrichment analysis of target genes in the cooperatively regulating miRNAs revealed the mutually exclusive functional landscape of miRNA cooperativity. In addition, we found that one miRNA in the miRNA association network could be involved in many cooperatively regulating miRNAs in a condition-specific and combinatorial manner. Sequence and structural similarity analysis within miRNA association network showed that pre-miRNA secondary structure may be involved in the expression of mature miRNA's function.

Conclusions

On the system level, we identified cooperatively regulating miRNAs in the miRNA association network. We showed that the secondary structures of pre-miRNAs in cooperatively regulating miRNAs are highly similar. This study demonstrates the potential importance of the secondary structures of pre-miRNAs in both cooperativity and specificity of target genes.

A high-throughput screen identifies miRNA inhibitors regulating lung cancer cell survival and response to paclitaxel

microRNAs (miRNAs) are small RNAs endogenously expressed in multiple organisms that regulate gene expression largely by decreasing levels of target messenger RNAs (mRNAs). Over the past few years, numerous studies have demonstrated critical roles for miRNAs in the pathogenesis of many cancers, including lung cancer. Cellular miRNA levels can be easily manipulated, showing the promise of developing miRNA-targeted oligos as next-generation therapeutic agents. In a comprehensive effort to identify novel miRNA-based therapeutic agents for lung cancer treatment, we combined a high-throughput screening platform with a library of chemically synthesized miRNA inhibitors to systematically identify miRNA inhibitors that reduce lung cancer cell survival and those that sensitize cells to paclitaxel. By screening three lung cancer cell lines with different genetic backgrounds, we identified miRNA inhibitors that potentially have a universal cytotoxic effect on lung cancer cells and miRNA inhibitors that sensitize cells to paclitaxel treatment, suggesting the potential of developing these miRNA inhibitors as therapeutic agents for lung cancer. We then focused on characterizing the inhibitors of three miRNAs (miR-133a/b, miR-361-3p, and miR-346) that have the most potent effect on cell survival. We demonstrated that two of the miRNA inhibitors (miR-133a/b and miR-361-3p) decrease cell survival by activating caspase-3/7-dependent apoptotic pathways and inducing cell cycle arrest in S phase. Future studies are certainly needed to define the mechanisms by which the identified miRNA inhibitors regulate cell survival and drug response, and to explore the potential of translating the current findings into clinical applications.

miR-93-directed downregulation of DAB2 defines a novel oncogenic pathway in lung cancer

The disabled homolog 2 (DAB2) gene was recently identified as a tumor suppressor gene with its expression down-regulated in multiple cancer types. The role of DAB2 in lung tumorigenesis, however, is not fully characterized, and the mechanisms of DAB2 dysregulation in lung cancer are not defined. Here we show that low DAB2 levels in lung tumor specimens are significantly correlated with poor patient survival, and that DAB2 over-expression significantly inhibits cell growth in cultured lung cancer cells, indicating its potent tumor suppressor function. We next identify that microRNA miR-93 functions as a potent repressor of DAB2 expression by directly targeting the 3′UTR of the DAB2 mRNA. Using in vitro and in vivo approaches, we demonstrate that miR-93 over-expression plays an important role in promoting lung cancer cell growth, and that its oncogenic function is primarily mediated by down-regulating DAB2 expression. Our clinical investigations further indicate that high tumor levels of miR-93 are correlated with poor survival of lung cancer patients. The correlations of both low DAB2 and high miR-93 expression with poor patient survival strongly support the critical role of the miR-93/DAB2 pathway in determining lung cancer progression.

Role of microRNA deregulation in the pathogenesis of diffuse large B-cell lymphoma (DLBCL)

MicroRNAs (miRNAs) are small endogenous RNA molecules that regulate gene expression at the post-transcriptional level through its sequence complementation with target mRNAs. An individual miRNA species can simultaneously influence the expression of multiple genes and conversely, several miRNAs can synchronously control expression of specific gene product mRNA levels. Thus, miRNAs expression in cells has to be precisely regulated and alterations in miRNA levels may cause an aberrant expression of genes involved in oncogenic pathways and consequently result in cancer development. Indeed, miRNA expression is often deregulated in many cancers, including B-cell lymphomas. Diffuse large B-cell lymphoma (DLBCL) is a heterogeneous group of B-cell lymphomas with different genetic backgrounds, morphologic features, and responses to therapy. Over the past decade, miRNAs emerged as a new tool for understanding DLBCL biology, and promising candidate molecular markers in DLBCL classification and treatment. In this review, we will focus on miRNAs aberrantly expressed in DLBCL and discuss the putative mechanisms of this deregulation. Additionally, we will summarize miRNAs' involvement in the identification of DLBCL subgroups, and their potential role as diagnostic/prognostic biomarkers as well as specific therapeutic targets for DLBCL.

MicroRNA miR-98 inhibits tumor angiogenesis and invasion by targeting activin receptor-like kinase-4 and matrix metalloproteinase-11

Angiogenesis and invasion are essential processes for solid tumor growth and dissemination. The tumor development process can be dependent on the activation of a series of signaling pathways, including growth factor-activated pathways. MicroRNAs have been shown to be critical for tumorigenesis, but their roles in cancer angiogenesis, invasion and other signaling pathways important for tumor development are still unclear in the context of tumor biology. We investigated the role of microRNA miR-98 in regulating tumor growth, invasion, and angiogenesis using a highly aggressive breast cancer model in vitro and in vitro. We found that the expression of miR-98 inhibited breast cancer cell proliferation, survival, tumor growth, invasion, and angiogenesis. Conversely, inhibition of endogenous miR-98 promoted cell proliferation, survival, tumor growth, invasion, and angiogenesis. It appeared that miR-98 inhibited angiogenesis by modulating endothelial cell activities including cell spreading, cell invasion and tubule formation. Interestingly, miR-98 reduced the expression of ALK4 and MMP11, both of which were potential targets of miR-98. Transfection of an anti-miR-98 construct increased the expression of both targets. We confirmed that mir-98 targeted the 3'-untranslated regions of ALK4 and MMP11. Finally, ALK4- and MMP11-specific siRNAs inhibited breast cancer cell proliferation, survival, and angiogenesis. Rescue experiments with ALK4 and MMP11 constructs reversed the anti-proliferative, anti-invasive and anti-angiogenic effects of miR-98. Our findings define a regulatory role of miR-98 in tumor angiogenesis and invasion through repressed ALK4 and MMP11 expression.

Dendritic cell-based immunotherapy in prevention and treatment of renal cell carcinoma: efficacy, safety, and activity of Ad-GM·CAIX in immunocompetent mouse models

The dendritic cell vaccine DC-Ad-GM·CAIX is an active, specific immunotherapy with the potential of providing a safe and effective therapy against renal cell carcinoma (RCC). Using immunocompetent Balb/c mouse models we tested the efficacy and mechanism of the vaccine to prevent and treat the growth of a syngeneic RCC (RENCA) engineered to overexpress the human TAA carbonic anhydrase IX (NPR-IX). In a prevention model, NPR-IX tumor development was specifically and significantly delayed by 13 days in DC-Ad-GM·CAIX-treated mice (P < 0.001), tumor volumes were 79% smaller (day 24, P < 0.007), and body weight was maintained at study termination compared with the controls. Six of these mice remained tumor-free for > 1 year. In a treatment model, NPR-IX tumors remained smaller in DC-Ad-GM·CAIX-treated mice for 8 days (P < 0.002), achieving a 60% growth inhibition at termination. No vaccine-related organ toxicity was observed in either model. The critical mechanistic parameter separating responsive from nonresponsive tumors was hCAIX protein expression, demonstrated by aggressive growth of tumors that did not express hCAIX protein and in sham-treated mice (DC-Ad-Null). No murine serum anti-hCAIX antibodies were detected. Moreover, altered mechanisms of immunoediting as a means for immune evasion were suggested by differential gene expression (Ccl1, Hmgb1, Fgl2, Cd209a, and Klra2) and therapy evasion miRNAs (miR-1186, miR-98, miR-5097, miR-1942, and miR-708) in tumors that evaded DC-Ad-GM·CAIX immunotherapy. This is the first study in immunocompetent mice that provides a proof of concept for the specificity, efficacy, safety, and activity of the DC-Ad-GM·CAIX immunotherapy, forming the basis for a first-in-human phase I trial in RCC patients.

MicroRNA expression profiling identifies molecular signatures associated with anaplastic large cell lymphoma

Anaplastic large-cell lymphomas (ALCLs) encompass at least 2 systemic diseases distinguished by the presence or absence of anaplastic lymphoma kinase (ALK) expression. We performed genome-wide microRNA (miRNA) profiling on 33 ALK-positive (ALK[+]) ALCLs, 25 ALK-negative (ALK[-]) ALCLs, 9 angioimmunoblastic T-cell lymphomas, 11 peripheral T-cell lymphomas not otherwise specified (PTCLNOS), and normal T cells, and demonstrated that ALCLs express many of the miRNAs that are highly expressed in normal T cells with the prominent exception of miR-146a. Unsupervised hierarchical clustering demonstrated distinct clustering of ALCL, PTCL-NOS, and the AITL subtype of PTCL. Cases of ALK(+) ALCL and ALK(-) ALCL were interspersed in unsupervised analysis, suggesting a close relationship at the molecular level. We identified an miRNA signature of 7 miRNAs (5 upregulated: miR-512-3p, miR-886-5p, miR-886-3p, miR-708, miR-135b; 2 downregulated: miR-146a, miR-155) significantly associated with ALK(+) ALCL cases. In addition, we derived an 11-miRNA signature (4 upregulated: miR-210, miR-197, miR-191, miR-512-3p; 7 downregulated: miR-451, miR-146a, miR-22, miR-455-3p, miR-455-5p, miR-143, miR-494) that differentiates ALK(-) ALCL from other PTCLs. Our in vitro studies identified a set of 32 miRNAs associated with ALK expression. Of these, the miR-17∼92 cluster and its paralogues were also highly expressed in ALK(+) ALCL and may represent important downstream effectors of the ALK oncogenic pathway.

Epigenetic Therapy in Lung Cancer - Role of microRNAs

Lung cancer is the leading cause of cancer deaths worldwide. microRNAs (miRNAs) are a class of small non-coding RNA species that have been implicated in the control of many fundamental cellular and physiological processes such as cellular differentiation, proliferation, apoptosis, and stem cell maintenance. Some miRNAs have been categorized as "oncomiRs" as opposed to "tumor suppressor miRs." This review focuses on the role of miRNAs in the lung cancer carcinogenesis and their potential as diagnostic, prognostic, or predictive markers.

miR-197 induces epithelial-mesenchymal transition in pancreatic cancer cells by targeting p120 catenin

Invasive ductal adenocarcinoma (IDA) of the pancreas manifests poor prognosis due to the early invasion and distant metastasis. In contrast, intraductal papillary mucinous adenoma or carcinoma (IPMA or IPMC) reveals better clinical outcomes. Various molecular mechanisms contribute to these differences but entire picture is still unclear. Recent researches emphasized the important role of miRNA in biological processes including cancer invasion and metastasis. We previously described that miR-126 is down-regulated in IDA compared with IPMA or IPMC, and miR-126 regulates the expression of invasion related molecule disintegrin and metalloproteinase domain-containing protein 9 (ADAM9). Assessing the difference of miRNA expression profiles of IDA, IPMA, and IPMC, we newly identified miR-197 as an up-regulated miRNA specifically in IDA. Expression of miR-197 in pancreatic cancer cells resulted in the induction of epithelial-mesenchymal transition (EMT) along with the down-regulation of p120 catenin which is a putative target of miR-197. Direct interaction between miR-197 and p120 catenin mRNA sequence was confirmed by 3'UTR assay, and knockdown of p120 catenin recapitulated EMT induction in pancreatic cancer cells. In situ hybridization of miR-197 and immunohistochemistry of p120 catenin showed mutually exclusive patterns suggesting pivotal role of miR-197 in the regulation of p120 catenin. This miR-197/p120 catenin axis could be a novel therapeutic target.

MicroRNA-93 regulates NRF2 expression and is associated with breast carcinogenesis

MicroRNAs (miRNA) are small non-coding RNAs that regulate the expression of approximately 60% of all human genes and play important roles in disease processes. Recent studies have demonstrated a link between dysregulated expression of miRNAs and breast carcinogenesis. Long-term estrogen exposure is implicated in development of human breast cancers, yet underlying mechanisms remain elusive. We have recently demonstrated that antioxidant vitamin C (vit C) prevents estrogen-induced breast tumor development. In this study, we investigated the role of vit C in the regulation of microRNA-93 (miR-93) and its target gene(s) in a rat model of mammary carcinogenesis. Female August Copenhagen Irish (ACI) rats were treated with vit C in the presence or absence of 17β-estradiol (E2) for 8 months. We demonstrate an increased expression of the miR-93 in E2-treated mammary tissues and in human breast cell lines and vit C treatment reverted E2-mediated increase in miR-93 levels. MiRNA target prediction programs suggest one of the target genes of miR-93 to be nuclear factor erythroid 2-related factor 2 (NRF2). In contrast with miR-93 expression, NRF2 protein expression was significantly decreased in E2-treated mammary tissues, mammary tumors, and in breast cancer cell lines, and its expression was significantly increased after vit C treatment. Ectopic expression of miR-93 decreased protein expression of NRF2 and NRF2-regulated genes. Furthermore, miR-93 decreased apoptosis, increased colony formation, mammosphere formation, cell migration and DNA damage in breast epithelial cells, whereas silencing of miR-93 in these cells inhibited these carcinogenic processes. Taken together, our findings suggest an oncogenic potential of miR-93 during E2-induced breast carcinogenesis.

MicroRNAs as lung cancer biomarkers and key players in lung carcinogenesis

Lung cancer is the leading cause of cancer deaths worldwide and few genetic markers enable to evaluate lung cancer risk. MicroRNAs (miRNAs) are small non-coding RNAs that regulate gene expression during various cell processes such as apoptosis, differentiation and development. In these last years, many works confirm a role for miRNAs in the initiation and progression of lung cancer. miRNA profiling has the potential to classify tumors with high accuracy and predict outcome. Here, we describe the roles of miRNA in lung carcinogenesis and the possibility to use them as biological markers for diagnostic, prognostic and predictive purposes.

Working together: combinatorial regulation by microRNAs

MicroRNAs (miRNAs) negatively regulate gene expression level of mRNA post-transcriptionally. Deep sequencing and large-scale screening methods have yielded about 1,500 miRNA sequences in human. Each miRNA contains a seed sequence that is required, but not sufficient, for the correct matching with its targets. Recent technological advances make it possible to capture the miRNAs with their cognate mRNAs at the RISC complex. These experiments have revealed thousands of validated mRNA-miRNA pairing events. In the context of human stem cells, 90% of the identified transcripts appear to be paired with at least two different miRNAs.In this chapter, we present a comprehensive outline for a combinatorial regulation mode by miRNAs. Initially, we summarize the computational and experimental evidence that support a combined effect of multiple miRNAs. Then, we describe miRror2.0, a platform specifically convened to consider the likelihood of miRNAs cooperativity in view of the targets, tissues and cell lines. We show that results from miRror2.0 can be further refined by an iterative procedure, calls Psi-miRror that gauges the robustness of the regulation. We illustrate the combinatorial regulation projected onto graphs of human pathways and show that these pathways are amenable to disruption by a small set of miRNAs. Finally, we propose that miRNA combinatorial regulation is an attractive regulatory strategy not only at the level of single target, but also at the level of pathways and cellular homeostasis. The joint operation of miRNAs is a powerful means to overcome the low specificity inherent in each individual miRNA.

Genomic loss of tumor suppressor miRNA-204 promotes cancer cell migration and invasion by activating AKT/mTOR/Rac1 signaling and actin reorganization

Increasing evidence suggests that chromosomal regions containing microRNAs are functionally important in cancers. Here, we show that genomic loci encoding miR-204 are frequently lost in multiple cancers, including ovarian cancers, pediatric renal tumors, and breast cancers. MiR-204 shows drastically reduced expression in several cancers and acts as a potent tumor suppressor, inhibiting tumor metastasis in vivo when systemically delivered. We demonstrated that miR-204 exerts its function by targeting genes involved in tumorigenesis including brain-derived neurotrophic factor (BDNF), a neurotrophin family member which is known to promote tumor angiogenesis and invasiveness. Analysis of primary tumors shows that increased expression of BDNF or its receptor tropomyosin-related kinase B (TrkB) parallel a markedly reduced expression of miR-204. Our results reveal that loss of miR-204 results in BDNF overexpression and subsequent activation of the small GTPase Rac1 and actin reorganization through the AKT/mTOR signaling pathway leading to cancer cell migration and invasion. These results suggest that microdeletion of genomic loci containing miR-204 is directly linked with the deregulation of key oncogenic pathways that provide crucial stimulus for tumor growth and metastasis. Our findings provide a strong rationale for manipulating miR-204 levels therapeutically to suppress tumor metastasis.

Identification of microRNA-98 as a therapeutic target inhibiting prostate cancer growth and a biomarker induced by vitamin D

The anti-tumor effect of vitamin D has been well recognized but its translational application is hindered by side effects induced by supra-physiological concentration of vitamin D required for cancer treatment. Thus, exploring the vitamin D tumor suppressive functional mechanism can facilitate improvement of its clinical application. We screened miRNA profiles in response to vitamin D and found that a tumor suppressive miRNA, miR-98, is transcriptionally induced by 1α,25-dihydroxyvitamin D(3) (1,25-VD) in LNCaP. Mechanistic dissection revealed that 1,25-VD-induced miR-98 is mediated through both a direct mechanism, enhancing the VDR binding response element in the promoter region of miR-98, and an indirect mechanism, down-regulating LIN-28 expression. Knockdown of miR-98 led to a reduction of 1,25-VD anti-growth effect and overexpression of miR-98 suppressed the LNCaP cells growth via inducing G2/M arrest. And CCNJ, a protein controlling cell mitosis, is down-regulated by miR-98 via targeting 3'-untranslated region of CCNJ. Interestingly, miR-98 levels in blood are increased upon 1,25-VD treatment in mice suggesting the biomarker potential of miR-98 in predicting 1,25-VD response. Together, the finding that growth inhibitive miR-98 is induced by 1,25-VD provides a potential therapeutic target for prostate cancer and a potential biomarker for 1,25-VD anti-tumor action.

MiR-93 enhances angiogenesis and metastasis by targeting LATS2

Here we report that miR-93, a miRNA in the miR-106B~25 cluster, a paralog of the miR-17-92 cluster, was significantly upregulated in human breast carcinoma tissues. We stably expressed miR-93 in the MT-1 human breast carcinoma cell line and found that tumors formed by the miR-93 cells contained more blood vessels than those formed by the control cells. Co-culture experiments indicated that the MT-1 cells displayed a high activity of adhesion with endothelial cells and could form larger and more tube-like structures with endothelial cells. Lung metastasis assays were performed in a mouse metastatic model, and it was found that expression of miR-93 promoted tumor cell metastasis to lung tissue. In cell culture, expression of miR-93 enhanced cell survival and invasion. We examined the potential target that mediated miR-93's effects and found that the large tumor suppressor, homology 2 (LATS2) was a target of miR-93. Higher levels of LATS2 were associated with cell death in the tumor mass. Silencing LATS2 expression promoted cell survival, tube formation and invasion, while ectopic expression of LATS2 decreased cell survival and invasion. These findings demonstrated that miR-93 promoted tumor angiogenesis and metastasis by suppressing LATS2 expression. Our results suggest that the inhibition of miR-93 function may be a feasible approach to repress tumor metastasis.

The novel miR-7515 decreases the proliferation and migration of human lung cancer cells by targeting c-Met

MicroRNAs (miRNA) are small noncoding RNAs that regulate gene expression in human diseases, including lung cancer. miRNAs have oncogenic and nononcogenic functions in lung cancer. In this study, we report the identification of a novel miRNA, miR-7515, from lung cancer cells. The novel miR-7515 was characterized using various predictive programs and experimental methods. miR-7515 was able to forming a stem-loop structure and its sequence was conserved in mammals. The expression level of miR-7515 in lung cancer cells and tissues was profiled using TaqMan miRNA assays. miR-7515 was downregulated in lung cancer compared with normal human lung cells and tissues. The target of miR-7515 was determined using a dual luciferase reporter assay. Expression of the target gene was determined by quantitative RT-PCR and Western blot analysis after transfection with miR-7515. miR-7515 directly suppressed human mesenchymal-epithelial transition factor (c-Met) by binding to the 3' untranslated region (UTR). Overexpression of miR-7515 significantly decreased cell-cycle-related proteins downstream of c-Met through c-Met inhibition. Cell proliferation and migration were examined using the XTT proliferation assay and the Transwell migration assay. miR-7515 led to decreased cell proliferation, migration and invasion in a lung cancer cell line. These results suggest that miR-7515 plays an important role in the proliferation and migration of lung cancer cells through c-Met regulation.

Micro-RNA-632 downregulates DNAJB6 in breast cancer

DNAJB6 is a constitutively expressed member of the HSP40 family. It has been described as a negative regulator of breast tumor progression and a regulator of epithelial phenotype. Expression of DNAJB6 is reported to be compromised with tumor progression. However, factors responsible for its downregulation are still undefined. We used a knowledge-based screen for identifying miRNAs capable of targeting DNAJB6. In this work, we present our findings that hsa-miR-632 (miR-632) targets the coding region of DNAJB6. Invasive and metastatic breast cancer cells express high levels of miR-632 compared with mammary epithelial cells. Analysis of RNA from breast tumor specimens reveals inverse expression patterns of DNAJB6 transcript and miR-632. In response to exogenous miR-632 expression, DNAJB6 protein levels are downregulated and the resultant cell population shows significantly increased invasive ability. Silencing endogenous miR-632 abrogates invasive ability of breast cancer cells and promotes epithelial like characteristics noted by E-cadherin expression with concomitant decrease in mesenchymal markers such as Zeb2 and Slug. Thus, miR-632 is a potentially important epigenetic regulator of DNAJB6, which contributes to the downregulation of DNAJB6 and plays a supportive role in malignant progression.

Toward a combinatorial nature of microRNA regulation in human cells

MicroRNAs (miRNAs) negatively regulate the levels of messenger RNA (mRNA) post-transcriptionally. Recent advances in CLIP (cross-linking immunoprecipitation) technology allowed capturing miRNAs with their cognate mRNAs. Consequently, thousands of validated mRNA–miRNA pairs have been revealed. Herein, we present a comprehensive outline for the combinatorial regulation by miRNAs. We implemented combinatorial and statistical constraints in the miRror2.0 algorithm. miRror estimates the likelihood of combinatorial miRNA activity in explaining the observed data. We tested the success of miRror in recovering the correct miRNA from 30 transcriptomic profiles of cells overexpressing a miRNA, and to identify hundreds of genes from miRNA sets, which are observed in CLIP experiments. We show that the success of miRror in recovering the miRNA regulation from overexpression experiments and CLIP data is superior in respect to a dozen leading miRNA-target prediction algorithms. We further described the balance between alternative modes of joint regulation that are executed by pairs of miRNAs. Finally, manipulated cells were tested for the possible involvement of miRNA in shaping their transcriptomes. We identified instances in which the observed transcriptome can be explained by a combinatorial regulation of miRNA pairs. We conclude that the joint operation of miRNAs is an attractive strategy to maintain cell homeostasis and overcoming the low specificity inherent in individual miRNA–mRNA interaction.

Endometrial miR-181a and miR-98 expression is altered during transition from normal into cancerous state and target PGR, PGRMC1, CYP19A1, DDX3X, and TIMP3

CONTEXT

Evidence suggests that a number of microRNA (miRNA) are aberrantly expressed in endometrial disorders with potential posttranscriptional regulation of their specific target genes, including ovarian steroid receptors.

OBJECTIVES

Our objective was to assess the endometrial expression of miR-98 and miR-181a and their respective target genes, progesterone (P4) receptor membrane component 1 (PGRMC1) and P4 receptor (PGR).

DESIGN, SETTING, AND PATIENTS

We evaluated tissue expression and in vitro regulation at an academic university medical center in endometrial biopsies and endometrial tissues from follicular and luteal phases with and without exposure to hormonal therapies and grade I-III endometrial cancer (n = 52).

INTERVENTIONS

INTERVENTIONS included endometrial biopsies and in vitro transfection.

MAIN OUTCOME MEASURES

We evaluated expression and function of miR-98 and miR-181a.

RESULTS

Aberrant expression of miR-98 and miR-181a is associated with endometrial transition from normal into cancerous states, which to some extent is influenced by hormonal milieu, and exhibited an inverse relationship with PGMRC1 and PGR expression, respectively. Treatments of Ishikawa cells with 17β-estradiol, P4, or medroxyprogesterone acetate had limited effects on miR-98, miR-181a, and PGRMC1 expression, whereas 17β-estradiol treatment increased PGR expression. In Ishikawa cells, gain of function of miR-98 repressed PGRMC1 and CYP19A1, and miR-181a repressed PGR, DDX3X, and TIMP3 at mRNA and protein levels through direct interactions with their respective 3'-untranslated regions and CCNE1 through miR-181a-induced DDX3X repression, with miR-98 reducing the rate of cell proliferation as compared with controls.

CONCLUSION

miR-98 and miR-181a through their regulatory functions on PGRMC1, PGR, CYP19A1, TIMP3, and DDX3X expression may influence a wide range of endometrial cellular activities during normal menstrual cycle and transition into disease states, including endometrial cancer.