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MicroRNAs (miRNAs) regulate complex patterns of gene expression, and the relevance of altered miRNA expression to ovarian cancer remains to be elucidated. By comprehensively profiling expression of miRNAs and mRNAs in serous ovarian tumors and cell lines and normal ovarian surface epithelium, we identified hundreds of potential miRNA-mRNA targeting associations underlying cancer. Functional overexpression of miR-31, the most underexpressed miRNA in serous ovarian cancer, repressed predicted miR-31 gene targets including cell cycle regulator E2F2. MIR31 and CDKN2A, which encodes p14ARF and p16INK4A, are located at 9p21.3, a genomic region commonly deleted in ovarian and other cancers. p14ARF promotes p53 activity, and E2F2 overexpression in p53 wild-type cells normally leads via p14ARF to an induction of p53-dependent apoptosis. In a number of serous cancer cell lines with a dysfunctional p53 pathway (i.e., OVCAR8, OVCA433, and SKOV3), miR-31 overexpression inhibited proliferation and induced apoptosis; however, in other lines (i.e., HEY and OVSAYO) with functional p53, miR-31 had no effect. Additionally, the osteosarcoma cell line U2OS and the prostate cancer cell line PC3 (p14ARF-deficient and p53-deficient, respectively) were also sensitive to miR-31. Furthermore, miR-31 overexpression induced a global gene expression pattern in OVCAR8 associated with better prognosis in tumors from patients with advanced stage serous ovarian cancer, potentially impacting many genes underlying disease progression. Our findings reveal that loss of miR-31 is associated with defects in the p53 pathway and functions in serous ovarian cancer and other cancers, suggesting that patients with cancers deficient in p53 activity might benefit from therapeutic delivery of miR-31.

The molecular mechanisms involved in epithelial ovarian cancer initiation and progression are just beginning to be elucidated. In particular, it has become evident that microRNAs (miRNAs), a class of molecules that post-trancriptionally regulates gene expression, play a major role in ovarian tumorigenesis. Several miRNA profiling studies have identified changes in miRNA patterns that take place during ovarian cancer development. While most deregulated miRNAs are down-regulated in cancer, and may therefore act as tumor suppressors, others are elevated and may represent novel oncogenes in this disease. A number of miRNAs identified as aberrantly expressed in ovarian carcinoma have been shown to have important functional roles in cancer development and may therefore represent targets for therapy. In addition, some of the miRNA patterns may have prognostic significance. The identification of functional targets represents a major hurdle in our understanding of miRNA function in ovarian carcinoma, but significant progress is being made. It is hoped that a better understanding of the miRNA expression and roles in ovarian cancer may provide new avenues for the detection, diagnosis, and therapy of this deadly disease.

Adrenocortical carcinoma (ACC) is an aggressive tumor showing frequent metastatic spread and poor survival. Although recent genome-wide studies of ACC have contributed to our understanding of the disease, major challenges remain for both diagnostic and prognostic assessments. The aim of this study was to identify specific microRNAs (miRNAs) associated with malignancy and survival of ACC patients. miRNA expression profiles were determined in a series of ACC, adenoma, and normal cortices using microarray. A subset of miRNAs showed distinct expression patterns in the ACC compared with adrenal cortices and adenomas. Among others, miR-483-3p, miR-483-5p, miR-210, and miR-21 were found overexpressed, while miR-195, miR-497, and miR-1974 were underexpressed in ACC. Inhibition of miR-483-3p or miR-483-5p and overexpression of miR-195 or miR-497 reduced cell proliferation in human NCI-H295R ACC cells. In addition, downregulation of miR-483-3p, but not miR-483-5p, and increased expression of miR-195 or miR-497 led to significant induction of cell death. Protein expression of p53 upregulated modulator of apoptosis (PUMA), a potential target of miR-483-3p, was significantly decreased in ACC, and inversely correlated with miR-483-3p expression. In addition, high expression of miR-503, miR-1202, and miR-1275 were found significantly associated with shorter overall survival among patients with ACC (P values: 0.006, 0.005, and 0.042 respectively). In summary, we identified additional miRNAs associated with ACC, elucidated the functional role of four miRNAs in the pathogenesis of ACC cells, demonstrated the potential involvement of the pro-apoptotic factor PUMA (a miR-483-3p target) in adrenocortical tumors, and found novel miRNAs associated with survival in ACC.

Background

Recent reports indicate that microRNAs (miRNAs) play a critical role in malignancies. However, the role that miRNAs play in pancreatic cancer remains to be determined. The purpose of this study was to investigate aberrantly expressed miRNAs in pancreatic cancer tissues and demonstrate their roles in disease progression.

Results

We detected the expression patterns of miRNAs in 10 pancreatic cancer tissues and their adjacent benign tissues by quantitative real time-PCR (qRT-PCR) and found that miR-15a and miR-214 were dysregulated in the tumor samples. This is the first time that miR-214 has been identified as aberrantly expressed in pancreatic cancer. In vitro experiments showed that overexpression of miR-15a inhibited the viability of pancreatic cancer cells, whereas overexpression of miR-214 decreased the sensitivity of the cells to gemcitabine (GEM). Furthermore, we identified WNT3A and FGF7 as potential targets of miR-15a and ING4 as a target of miR-214.

Conclusions

Aberrant expression of miRNAs such as miR-15a and miR-214 results in different cellular effects in pancreatic cancer. Downregulation of miR-15a might contribute to proliferation of pancreatic cancer cells, whereas upregulation of miR-214 in pancreatic cancer specimens might be related to the poor response of pancreatic cancer cells to chemotherapy. MiR-15a directly targets multiple genes relevant in pancreatic cancer, suggesting that it may serve as a novel therapeutic target for treatment of the disease.

Dysregulation of microRNAs (miRNAs) has been found to be associated with a variety of diseases, including epithelial ovarian cancer (EOC). Recently, miR-100 was reported to be downregulated in human ovarian carcinoma, however, the clinical significance and functional roles of miR-100 expression in human EOC are unclear. TaqMan real-time quantitative RT-PCR assay was performed to detect the expression of miR-100 in 98 EOC tissues and 15 adjacent normal epithelial tissues. The relationship between miR-100 expression and clinicopathological factors in 98 EOC patients was statistically analyzed. The effect of miR-100 expression on patient survival was determined. Finally, the role of miR-100 in EOC cell growth and its possible mechanisms were analyzed with miR-100 precursor or inhibitor-transfected cells. We showed that the level of miR-100 was significantly lower in EOC tissues compared to adjacent normal tissues. Low miR-100 expression was found to be closely correlated with advanced FIGO stage, higher serum CA125 expression level and lymph node involvement. Also, low miR-100 expression was correlated with shorter overall survival of EOC patients, and multivariate analysis showed that the status of miR-100 expression was an independent predictor of overall survival in EOC. Additionally, miR-100 could affect the growth of EOC cells by post-transcriptionally regulating polo-like kinase 1 (PLK1) expression. Together, these results suggest that low miR-100 expression may be an independent poor prognostic factor and miR-100 can function as a tumor suppressor by targeting PLK1 in human EOCs.

Background

The Cancer Genome Atlas (TCGA) Network recently comprehensively catalogued the molecular aberrations in 487 high-grade serous ovarian cancers, with much remaining to be elucidated regarding the microRNAs (miRNAs). Here, using TCGA ovarian data, we surveyed the miRNAs, in the context of their predicted gene targets.

Methods and Results

Integration of miRNA and gene patterns yielded evidence that proximal pairs of miRNAs are processed from polycistronic primary transcripts, and that intronic miRNAs and their host gene mRNAs derive from common transcripts. Patterns of miRNA expression revealed multiple tumor subtypes and a set of 34 miRNAs predictive of overall patient survival. In a global analysis, miRNA:mRNA pairs anti-correlated in expression across tumors showed a higher frequency of in silico predicted target sites in the mRNA 3′-untranslated region (with less frequency observed for coding sequence and 5′-untranslated regions). The miR-29 family and predicted target genes were among the most strongly anti-correlated miRNA:mRNA pairs; over-expression of miR-29a in vitro repressed several anti-correlated genes (including DNMT3A and DNMT3B) and substantially decreased ovarian cancer cell viability.

Conclusions

This study establishes miRNAs as having a widespread impact on gene expression programs in ovarian cancer, further strengthening our understanding of miRNA biology as it applies to human cancer. As with gene transcripts, miRNAs exhibit high diversity reflecting the genomic heterogeneity within a clinically homogeneous disease population. Putative miRNA:mRNA interactions, as identified using integrative analysis, can be validated. TCGA data are a valuable resource for the identification of novel tumor suppressive miRNAs in ovarian as well as other cancers.

Background

We are interested in identifying molecular markers that can aid in the diagnosis of adrenocortical carcinoma (ACC). The aim of this study was to identify microRNAs (miRNAs or miRs) that are differentially expressed in malignant adrenocortical tumors as compared to benign tumors and assess their potential as diagnostic predictors.

Methods

Differentially expressed miRNAs were identified using microarray profiling of adrenocortical tumors and validated by quantitative real-time RT-PCR.

Results

Microarray profiling in benign and primary malignant adrenocortical tumors revealed a number of significant differences between these histological groups. Using directed quantitative RT-PCR analysis on a subset of these differentially expressed miRNAs, we determined that miRs −100, −125b, and −195 were significantly downregulated and miR-483-5p was significantly upregulated in malignant as compared to benign tumors. Furthermore, our work shows that miR-483-5p expression can accurately categorize tumors as benign or malignant.

Conclusions

We identified four miRNAs that are dysregulated in adrenocortical carcinoma. The high expression of one of these, miR-483-5p, appears to be a defining characteristic of adrenocortical malignancies and can be used to accurately distinguish between benign and malignant adrenocortical tumors.

The deregulation of microRNA (miRNA) is frequently associated with a variety of cancers, including hepatocellular carcinoma (HCC). In this study, we identified 10 upregulated miRNAs (miR-217, miR-518b, miR-517c, miR-520g, miR-519a, miR-522, miR-518e, miR-525-3p, miR-512-3p and miR-518a-3p) and 10 downregulated miRNAs (miR-138, miR-214, miR-214#, miR-27a#, miR-199a-5p, miR-433, miR-511, miR-592, miR-483-5p and miR-483-3p) by Taqman miRNAs array and quantitative real-time PCR (qRT–PCR) confirmation. Additionally, we investigated the expression and possible role of miR-138 in HCC. qRT–PCR results showed that miR-138 was downregulated in 77.8%(14/18) of HCC tissues compared with adjacent non-tumor tissues. Overexpression of miR-138 reduced cell viability and colony formation by induction of cell arrest in HCC cell lines and inhibited tumor cell growth in xenograft nude mice. The use of miR-138 inhibitor increased cell viability and colony formation in HCC cell lines and tumor cell growth in xenograft nude mice. Using TargetScan predictions, CCND3 was defined as a potential direct target of miR-138. Furthermore, CCND3 protein expression was observed to be negatively correlated with miR-138 expression in HCC tissues. The dual-luciferase reporter gene assay results showed that CCND3 was a direct target of miR-138. The use of miR-138 mimic or inhibitor could decrease or increase CCND3 protein levels in HCC cell lines. We conclude that the frequently downregulated miR-138 can regulate CCND3 and function as a tumor suppressor in HCC. Therefore, miR-138 may serve as a useful therapeutic agent for miRNA-based HCC therapy.

MicroRNAs (miRNAs) have been shown to be involved in different aspects of cancer biology including tumor angiogenesis. In this study, we identified that two miRNAs, miR-199a and miR-125b were downregulated in ovarian cancer tissues and cell lines. Overexpression of miR-199a and miR-125b inhibited tumor-induced angiogenesis associated with the decrease of HIF-1α and VEGF expression in ovarian cancer cells. Moreover, the levels of miR-199a and miR-125b were negatively correlated with VEGF mRNA levels in ovarian tissues. We further showed that direct targets of miR-199a and miR-125b HER2 and HER3 were functionally relevant. Forced expression of HER2 and HER3 rescued miR-199a- and miR-125b-inhibiting angiogenesis responses and Akt/p70S6K1/HIF-1α pathway. This study provides a rationale for new therapeutic approach to suppress tumor angiogenesis using miR-199a, miR-125b, or their mimics for ovarian cancer treatment in the future.

Background

MicroRNAs (miRNAs) are a class of small noncoding RNAs that regulate gene expression. They are aberrantly expressed in many types of cancers. In this study, we determined the genome-wide miRNA profiles in bladder urothelial carcinoma by deep sequencing.

Methodology/Principal Findings

We detected 656 differentially expressed known human miRNAs and miRNA antisense sequences (miRNA*s) in nine bladder urothelial carcinoma patients by deep sequencing. Many miRNAs and miRNA*s were significantly upregulated or downregulated in bladder urothelial carcinoma compared to matched histologically normal urothelium. hsa-miR-96 was the most significantly upregulated miRNA and hsa-miR-490-5p was the most significantly downregulated one. Upregulated miRNAs were more common than downregulated ones. The hsa-miR-183, hsa-miR-200b∼429, hsa-miR-200c∼141 and hsa-miR-17∼92 clusters were significantly upregulated. The hsa-miR-143∼145 cluster was significantly downregulated. hsa-miR-182, hsa-miR-183, hsa-miR-200a, hsa-miR-143 and hsa-miR-195 were evaluated by Real-Time qPCR in a total of fifty-one bladder urothelial carcinoma patients. They were aberrantly expressed in bladder urothelial carcinoma compared to matched histologically normal urothelium (p<0.001 for each miRNA).

Conclusions/Significance

To date, this is the first study to determine genome-wide miRNA expression patterns in human bladder urothelial carcinoma by deep sequencing. We found that a collection of miRNAs were aberrantly expressed in bladder urothelial carcinoma compared to matched histologically normal urothelium, suggesting that they might play roles as oncogenes or tumor suppressors in the development and/or progression of this cancer. Our data provide novel insights into cancer biology.

MicroRNAs are often aberrantly expressed in human neoplasms and are postulated to play a role in neoplastic initiation and progression. miR-221 and miR-222 negatively regulate expression of CDKN1B (p27)and CDKN1C (p57), two cell cycle regulators expressed in ovarian surface epithelium and down-regulated in ovarian carcinomas. We characterized miR-221 and miR-222 expression in 49 sporadic high grade ovarian carcinomas and determined whether somatic mutation or epigenetic alterations explained the differences in expression of these miRNAs. We correlated these findings with protein expression of CDKN1B and CDKN1C as assessed by immunohistochemistry. Expression of miR-221 and miR-222 were closely correlated with each other (P=0.0001). Interestingly, a lower ratio of miR-221 to miR-222 expression was significantly correlated with worse overall survival (P=0.01) and remained a significant predictor of overall survival in multivariate analysis using the co-variate adequacy of surgical cytoreduction (P=0.03). Higher miR-222 and miR-221 expression were significantly associated with decreased CDKN1C expression (P=0.009 and 0.01). In contrast, CDKN1B expression was not associated with miR-221 or miR-222 expression. Neither somatic mutations nor methylation of the studied region explained the alterations in miR-221 and miR-222 expression in most carcinomas.

Background

MicroRNAs (miRNA) are 20∼25 nucleotide non-coding RNAs that inhibit the translation of targeted mRNA, and they have been implicated in the development of human malignancies. High grade serous ovarian carcinomas, the most common and lethal subtype of ovarian cancer, can occur sporadically or in the setting of BRCA1/2 syndromes. Little is known regarding the miRNA expression profiles of high grade serous carcinoma in relation to BRCA1/2 status, and compared to normal tubal epithelium, the putative tissue of origin for high grade serous carcinomas.

Methodology/Principal Findings

Global miRNA expression profiling was performed on a series of 33 high grade serous carcinomas, characterized with respect to BRCA1/2 status (mutation, epigenetic silencing with loss of expression or normal), and with clinical follow-up, together with 2 low grade serous carcinomas, 2 serous borderline tumors, and 3 normal fallopian tube samples, using miRNA microarrays (328 human miRNA). Unsupervised hierarchical clustering based on miRNA expression profiles showed no clear separation between the groups of carcinomas with different BRCA1/2 status. There were relatively few miRNAs that were differentially expressed between the genotypic subgroups. Comparison of 33 high grade serous carcinomas to 3 normal fallopian tube samples identified several dysregulated miRNAs (false discovery rate <5%), including miR-422b and miR-34c. Quantitative RT-PCR analysis performed on selected miRNAs confirmed the pattern of differential expression shown by microarray analysis. Prognostically, lower level miR-422b and miR-34c in high grade serous carcinomas were both associated with decreased disease-specific survival by Kaplan-Meier analysis (p<0.05).

Conclusions/Significance

High grade serous ovarian carcinomas with and without BRCA1/2 abnormalities demonstrate very similar miRNA expression profiles. High grade serous carcinomas as a group exhibit significant miRNA dysregulation in comparison to tubal epithelium and the levels of miR-34c and miR-422b appear to be prognostically important.

Head and neck squamous cell carcinoma (HNSCC) cells exposed to cisplatin (CIS) displayed a dramatic ATM-dependent phosphorylation of ΔNp63α that leads to the transcriptional regulation of downstream mRNAs. Here, we report that phospho (p)-ΔNp63α transcriptionally deregulates miRNA expression after CIS treatment. Several p-ΔNp63α-dependent microRNA species (miRNAs) were deregulated in HNSCC cells upon CIS exposure, including miR-181a, miR-519a, and miR-374a (downregulated) and miR-630 (upregulated). Deregulation of miRNA expression led to subsequent modulation of mRNA expression of several targets (TP53-S46, HIPK2, ATM, CDKN1A and 1B, CASP3, PARP1 and 2, DDIT1 and 4, BCL2 and BCL2L2, TP73, YES1, and YAP1) that are involved in the apoptotic process. Our data support the notion that miRNAs are critical downstream targets of p-ΔNp63α and mediate key pathways implicated in the response of cancer cells to chemotherapeutic drugs.

Background:

MicroRNAs (miRNAs) are small noncoding RNA molecules with an essential role in regulation of gene expression. miRNA expression profiles differ between tumor and normal control tissue in many types of cancers and miRNA profiling is seen as a promising field for finding new diagnostic and prognostic tools.

Materials and Methods:

In this study, we have analyzed expression of three miRNAs, miR-21, miR-125b, and miR-203, and their potential target proteins p53 and p63, known to be deregulated in squamous cell carcinoma of the head and neck (SCCHN), in two distinct and one mixed subsite in squamous cell carcinoma in the oral cavity.

Results:

We demonstrate that levels of miRNA differ between tumors of different subsites with tongue tumors showing significant deregulation of all three miRNAs, whereas gingival tumors only showed significant downregulation of miR-125b and the mixed group of tumors in tongue/floor of the mouth showed significant deregulation of miR-21 and miR-125b. In the whole group of oral squamous cell carcinoma (SCC), a significant negative correlation was seen between miR-125b and p53 as well as a significant correlation between TP53 mutation status and miR-125b.

Conclusion:

The present data once again emphasize the need to take subsite into consideration when analyzing oral SCC and clearly show that data from in vitro studies cannot be transferred directly to the in vivo situation.

Oncogenic activation of Bmi-1 is found in a wide variety of epithelial malignancies including ovarian cancer, yet a specific mechanism for over expression of Bmi-1 has not been determined. Thus realizing the immense pathological significance of Bmi-1 in cancer, we wanted to investigate if microRNA aberrations played a role in the regulation of Bmi-1 in ovarian cancer. In this report we identify two microRNAs, miR-15a and miR-16 that are under expressed in ovarian cell lines and in primary ovarian tissues. We demonstrate that these miRNAs directly target the Bmi-1 3’ UTR and significantly correlate with Bmi-1 protein levels in ovarian cancer patients and cell lines. Furthermore, Bmi-1 protein levels are down regulated in response to miR-15a or miR-16 expression and lead to significant reduction in ovarian cancer cell proliferation and clonal growth. These findings suggest the development of therapeutic strategies by restoring miR-15a and miR-16 expression in ovarian cancer and in other cancers that involve up regulation of Bmi-1.

Background

MicroRNAs (miRNAs) regulate gene expression by binding to mRNA, and can function as oncogenes or tumor suppressors depending on the target. In this study, using qRT-PCR, we examined the expression of six miRNAs (miR-21, miR-31, miR-92a, miR-101, miR-106a and miR-145) in tumors from 193 prospectively recruited patients with colorectal cancer, and associations with clinicopathological parameters and patient outcome were analyzed. The miRNAs were chosen based on previous studies for their biomarker potential and suggested biological relevance in colorectal cancer.

Methods

The miRNA expression was examined by qRT-PCR. Associations between miRNA expression and clinicopathological variables were explored using Mann–Whitney U and Kruskal-Wallis test while survival was estimated using the Kaplan-Meier method and compared using the log-rank test.

Results

MiR-101 was hardly expressed in the tumor samples, while for the other miRNAs, variable expression levels and expression ranges were observed, with miR-21 being most abundantly expressed relative to the reference (RNU44). In our study cohort, major clinical significance was demonstrated only for miR-31, as high expression was associated with advanced tumor stage and poor differentiation. No significant associations were found between expression of the investigated miRNAs and metastasis-free or overall survival.

Conclusions

Investigating the expression of six miRNAs previously identified as candidate biomarkers in colorectal cancer, few clinically relevant associations were detected in our patient cohort. Our results emphasize the importance of validating potential tumor markers in independent patient cohorts, and indicate that the role of miRNAs as colorectal cancer biomarkers is still undetermined.

Purpose

MicroRNA (miRNA) is a new class of small, noncoding RNA. The purpose of this study was to determine if miRNAs are differentially expressed in hepatocellular carcinoma (HCC).

Experimental Design

More than 200 precursor and mature miRNAs were profiled by real-time PCR in 43 and 28 pairs of HCC and adjacent benign liver, respectively, and in normal liver specimens.

Results

Several miRNAs including miR-199a, miR-21, and miR-301 were differentially expressed in the tumor compared with adjacent benign liver. A large number of mature and precursor miRNAs were up-regulated in the adjacent benign liver specimens that were both cirrhotic and hepatitis-positive compared with the uninfected, noncirrhotic specimens (P < 0.01). Interestingly, all of the miRNAs in this comparison had increased expression and none were decreased. The expression of 95 randomly selected mRNAs was not significantly altered in the cirrhotic and hepatitis-positive specimens, suggesting a preferential increase in the transcription of miRNA. Comparing the miRNA expression in the HCC tumors with patient’s survival time revealed two groups of patients; those with predominantly lower miRNA expression and poor survival and those with predominantly higher miRNA expression and good survival (P < 0.05). A set of 19 miRNAs significantly correlated with disease outcome. A number of biological processes including cell division, mitosis, and G1-S transition were predicted to be targets of the19miRNAs in this group.

Conclusion

We show that a global increase in the transcription of miRNA genes occurs in cirrhotic and hepatitis-positive livers and that miRNA expression may prognosticate disease out-come in HCC.

MicroRNAs (miRNA) are small endogenously expressed non-coding RNAs that negatively regulate expression of protein-coding genes at the translational level. Accumulating evidence, such as aberrant expression of miRNAs, suggests that they play a role in the development of cancer. They have been identified in various tumor types, demonstrating that different sets of miRNAs are usually deregulated in different cancers. To identify the miRNA signatures specific for Hepatitis C virus (HCV)-associated Hepatocellular carcinoma (HCC), miRNA expression profiling of 32 HCC post-HCV infected, 74 HCV-positive and 12 control individuals was carried out using whole genome expression profiling. Differential expression of two individual miRNAs between control and high risk HCV patients was detected and found to possibly target genes related to HCC development and progression. The sensitivity and specificity of miR-618 for detecting HCC among HCV-positive individuals was found to be 64% and 68%, respectively. Whereas, the sensitivity and specificity of miR-650 were 72% and 58%, respectively. Additionally, the sensitivity and specificity for miR-618/650 in tandem were 58% and 75%, respectively. These predictive values are greatly improved compared to the traditional α-feto protein (AFP) level-based detection method. The proposed HCC miRNA signatures may therefore be of great value for the early diagnosis of HCC, before the onset of disease in HCV-positive patients. The significance of this approach is amplified by the use of urine as a sample source as it offers a non-invasive approach for developing screening methods that can reduce mortality rates.

The Epstein-Barr virus (EBV) is highly associated with nasopharyngeal carcinoma (NPC), and it regulates some microRNAs (miRNAs) that are involved in the development of cancer. The role of EBV in the deregulation of cellular miRNAs and how this affects the progression of NPC remain to be investigated. An analysis of the miRNA profile in an EBV-infected cell line revealed that miRNA 203 (miR-203) was downregulated. miR-203 is expressed specifically in epithelial cells. This downregulation of miR-203 was further verified and functionally analyzed. miR-203 was downregulated substantially in epithelial cells and NPC tissues that were latently infected with EBV. Downregulation of miR-203 also occurred during the early stage of EBV infection. Furthermore, the viral oncoprotein, latent membrane protein 1 (LMP1), was responsible for downregulation of miR-203. Removal of the latent EBV genome or suppression of LMP1 resulted in restoration of miR-203 expression. EBV-LMP1 mediated the downregulation of miR-203 at the primary transcript level. E2F3 and CCNG1 were identified as target genes of miR-203. Ectopic expression of miR-203 inhibited EBV-induced S-phase entry and transformation in vivo. Overexpression of the targets overcame the effects of miR-203 mimics on the cell cycle, and the expression of target genes in tumor models was inhibited by miR-203. Inhibitors of Jun N-terminal protein kinase (JNK) and NF-κB blocked miR-203 downregulation. These results imply that EBV promotes malignancy by downregulating cellular miR-203, which contributes to the etiology of NPC.

Primary liver cancer, predominantly consisting of hepatocellular carcinoma (HCC), is one of the most common and aggressive human malignancies worldwide. MicroRNAs (miRNAs) are a class of small non-coding RNAs that regulate gene expression post-transcriptionally. Emerging evidence indicates that miRNAs are often deregulated in HCC, and that some specific miRNAs are associated with the clinicopathological features of HCC. Recent work demonstrates that miRNAs have essential roles in HCC progression and directly contribute to cell proliferation, avoidance of apoptotic cell death, and metastasis of HCC by targeting a large number of critical protein-coding genes. The discovery of the aberrantly expressed miRNAs and their corresponding targets has opened a novel avenue to investigate the molecular mechanism of HCC progression and to develop potential therapeutics against HCC. In this review, we summarise current knowledge about the roles and validated targets of miRNAs in liver cancer progression.

microRNAs (miRNAs) are evolutionarily conserved small noncoding RNAs, also known as micromanagers of gene expression. Polymorphisms in the miRNA pathway (miR-polymorphisms) are emerging as powerful tools to study the biology of a disease and have the potential to be used in disease prognosis and diagnosis. Advancements in the miRNA field also indicate a clear involvement of deregulated miRNA gene signatures in cancers, and several polymorphisms in pre-miRNA, miRNA binding sites or targets have been found to be associated with various cancers. The miRNA polymorphisms have also been reported to influence tumor aggressiveness as well as survival of cancer patients. miRNAs have a revolutionary impact on cancer research over recent years. They emerge as important players in tumorigenesis, leading to a paradigm shift in oncology. The extensive and comprehensive use of miRNA microarrays has enabled the identification of a number of miRNAs as potential biomarkers for cancer. Many miRNAs have been identified to act as oncogenes, tumor suppressors, or even modulators of cancer stem cells and metastasis. Some studies not only reported the identified miRNA biomarkers, but also deciphered their target genes and the underlying mechanisms. The rapid discovery of many miRNA targets and their relevant pathways has contributed to the development of miRNA-based therapeutics.

MicroRNAs (miRNAs) are small non-coding RNAs that function as endogenous silencers of numerous target genes. Hundreds of miRNAs have been identified in the human genome. miRNAs are expressed in a tissue-specific manner and play important roles in cell proliferation, apoptosis, and differentiation. Aberrant expression of miRNAs may also contribute to the development and progression of human hepatobiliary and pancreatic cancers. Recent studies have shown that some miRNAs play roles as tumor suppressors or oncogenes in hepatobiliary and pancreatic cancers. miR-122, let-7 family, and miR-101 are down-regulated in hepatocellular carcinoma (HCC), suggesting that it is a potential tumor suppressor of HCC. miR-221 and miR-222 are up-regulated in HCC and may act as oncogenic miRNAs in hepatocarcinogenesis. miRNA expression profiling may be a powerful clinical tool for diagnosis and regulation of miRNA expression could be a novel therapeutic strategy for hepatobiliary and pancreatic cancers. In this review, we summarize current knowledge about the roles of important tumor suppressor microRNAs and oncogenic microRNAs in hepatobiliary and pancreatic cancers.

Background

MicroRNAs are important regulators of transcription in hematopoiesis. Their expression deregulations were described in association with pathogenesis of some hematological malignancies. This study provides integrated microRNA expression profiling at different phases of chronic myeloid leukemia (CML) with the aim to identify microRNAs associated with CML pathogenesis. The functions of in silico filtered targets are in this report annotated and discussed in relation to CML pathogenesis.

Results

Using microarrays we identified differential expression profiles of 49 miRNAs in CML patients at diagnosis, in hematological relapse, therapy failure, blast crisis and major molecular response. The expression deregulation of miR-150, miR-20a, miR-17, miR-19a, miR-103, miR-144, miR-155, miR-181a, miR-221 and miR-222 in CML was confirmed by real-time quantitative PCR. In silico analyses identified targeted genes of these miRNAs encoding proteins that are involved in cell cycle and growth regulation as well as several key signaling pathways such as of mitogen activated kinase-like protein (MAPK), epidermal growth factor receptor (EGFR, ERBB), transforming growth factor beta (TGFB1) and tumor protein p53 that are all related to CML. Decreased levels of miR-150 were detected in patients at diagnosis, in blast crisis and 67% of hematological relapses and showed significant negative correlation with miR-150 proved target MYB and with BCR-ABL transcript level.

Conclusions

This study uncovers microRNAs that are potentially involved in CML and the annotated functions of in silico filtered targets of selected miRNAs outline mechanisms whereby microRNAs may be involved in CML pathogenesis.

Background

Biomarkers for the diagnostic classification of pancreatic cysts are urgently needed. Deregulated microRNA (miRNAs) expression is widespread in pancreatic cancer. We assessed whether aberrant miRNAs in pancreatic cyst fluid could be used as potential biomarkers for cystic precursor lesions of pancreatic cancer.

Methods

Cyst fluid specimens were prospectively collected from 40 surgically resected pancreatic cysts, and small RNAs were extracted. The ‘mucinous’ cohort included 14 intraductal papillary mucinous neoplasms (including 3 with an associated adenocarcinoma) and 10 mucinous cystic neoplasms; the ‘nonmucinous’ cohort included 11 serous cystadenomas and 5 other benign cysts. Quantitative reverse transcription PCR was performed for five miRNAs (miR-21, miR-155, miR-221, miR-17-3p, miR-191), which were previously reported as overexpressed in pancreatic adenocarcinomas.

Results

Significantly higher expression of miR-21, miR-221, and miR-17-3p was observed in the mucinous versus nonmucinous cysts (p < 0.01), with the mean relative fold differences being 7.0-, 7.9-, and 5.4-fold, respectively. Receiver operating characteristic curves demonstrated the highest median area under the curve for miR-21, with a median specificity of 76%, at a sensitivity of 80%.

Conclusion

This pilot study demonstrates that profiling miRNAs in pancreatic cyst fluid samples is feasible and can yield potential biomarkers for the classification of cystic lesions of the pancreas.

Background

MicroRNAs (miRNAs) represent a class of small non-coding RNAs that control gene expression by targeting mRNAs and triggering either translation repression or RNA degradation. Emerging evidence suggests the potential involvement of altered regulation of miRNA in the pathogenesis of cancers, and these genes are thought to function as both tumor suppressors and oncogenes.

Methodology/Principal Findings

Using microRNA microarrays, we identify several miRNAs aberrantly expressed in human ovarian cancer tissues and cell lines. miR-221 stands out as a highly elevated miRNA in ovarian cancer, while miR-21 and several members of the let-7 family are found downregulated. Public databases were used to reveal potential targets for the highly differentially expressed miRNAs. In order to experimentally identify transcripts whose stability may be affected by the differentially expressed miRNAs, we transfected precursor miRNAs into human cancer cell lines and used oligonucleotide microarrays to examine changes in the mRNA levels. Interestingly, there was little overlap between the predicted and the experimental targets or pathways, or between experimental targets/pathways obtained using different cell lines, highlighting the complexity of miRNA target selection.

Conclusion/Significance

Our results identify several differentially expressed miRNAs in ovarian cancer and identify potential target transcripts that may be regulated by these miRNAs. These miRNAs and their targets may have important roles in the initiation and development of ovarian cancer.