Expression of microRNAs and protein-coding genes associated with perineural invasion in prostate cancer

Microrna profiling analysis of differences between the melanoma of young adults and older adults

BACKGROUND

This study represents the first attempt to perform a profiling analysis of the intergenerational differences in the microRNAs (miRNAs) of primary cutaneous melanocytic neoplasms in young adult and older age groups. The data emphasize the importance of these master regulators in the transcriptional machinery of melanocytic neoplasms and suggest that differential levels of expressions of these miRs may contribute to differences in phenotypic and pathologic presentation of melanocytic neoplasms at different ages.

METHODS

An exploratory miRNA analysis of 666 miRs by low density microRNA arrays was conducted on formalin fixed and paraffin embedded tissues (FFPE) from 10 older adults and 10 young adults including conventional melanoma and melanocytic neoplasms of uncertain biological significance. Age-matched benign melanocytic nevi were used as controls.

RESULTS

Primary melanoma in patients greater than 60 years old was characterized by the increased expression of miRs regulating TLR-MyD88-NF-kappaB pathway (hsa-miR-199a), RAS/RAB22A pathway (hsa-miR-204); growth differentiation and migration (hsa-miR337), epithelial mesenchymal transition (EMT) (let-7b, hsa-miR-10b/10b*), invasion and metastasis (hsa-miR-10b/10b*), hsa-miR-30a/e*, hsa-miR-29c*; cellular matrix components (hsa-miR-29c*); invasion-cytokinesis (hsa-miR-99b*) compared to melanoma of younger patients. MiR-211 was dramatically downregulated compared to nevi controls, decreased with increasing age and was among the miRs linked to metastatic processes. Melanoma in young adult patients had increased expression of hsa-miR-449a and decreased expression of hsa-miR-146b, hsa-miR-214*. MiR-30a* in clinical stages I-II adult and pediatric melanoma could predict classification of melanoma tissue in the two extremes of age groups. Although the number of cases is small, positive lymph node status in the two age groups was characterized by the statistically significant expression of hsa-miR-30a* and hsa-miR-204 (F-test, p-value < 0.001).

CONCLUSIONS

Our findings, although preliminary, support the notion that the differential biology of melanoma at the extremes of age is driven, in part, by deregulation of microRNA expression and by fine tuning of miRs that are already known to regulate cell cycle, inflammation, Epithelial-Mesenchymal Transition (EMT)/stroma and more specifically genes known to be altered in melanoma. Our analysis reveals that miR expression differences create unique patterns of frequently affected biological processes that clearly distinguish old age from young age melanomas. This is a novel characterization of the miRnomes of melanocytic neoplasms at two extremes of age and identifies potential diagnostic and clinico-pathologic biomarkers that may serve as novel miR-based targeted modalities in melanoma diagnosis and treatment.

MiR-218 inhibits invasion and metastasis of gastric cancer by targeting the Robo1 receptor

MicroRNAs play key roles in tumor metastasis. Here, we describe the regulation and function of miR-218 in gastric cancer (GC) metastasis. miR-218 expression is decreased along with the expression of one of its host genes, Slit3 in metastatic GC. However, Robo1, one of several Slit receptors, is negatively regulated by miR-218, thus establishing a negative feedback loop. Decreased miR-218 levels eliminate Robo1 repression, which activates the Slit-Robo1 pathway through the interaction between Robo1 and Slit2, thus triggering tumor metastasis. The restoration of miR-218 suppresses Robo1 expression and inhibits tumor cell invasion and metastasis in vitro and in vivo. Taken together, our results describe a Slit-miR-218-Robo1 regulatory circuit whose disruption may contribute to GC metastasis. Targeting miR-218 may provide a strategy for blocking tumor metastasis.

The transcriptional regulation of miR-21, its multiple transcripts, and their implication in prostate cancer

MicroRNAs (miRNAs) are a natural part of the most recently discovered and global regulatory pathway known as RNA interference. Functional studies have shown how specific miRNAs can function as tumor suppressors or oncogenes and, correspondingly, deregulated miRNA profiles have been observed in prostate and other cancers. However, the upstream pathways which regulate miRNA expression are only currently being uncovered. The Androgen Receptor (AR) is a nuclear hormone receptor and transcription factor which plays a paramount role in prostate cancer (PCa) pathobiology. We performed high throughput miRNA microarray analysis on two AR-responsive cell lines to identified 16 candidate AR-regulated miRNAs.(1) One of the most androgen-induced candidates was a known oncogenic miRNA, miR-21. In a small study of early grade PCa samples we found that miR-21 levels were frequently elevated in comparison to adjacent normal tissue. This observation was supported in the literature(2,3) and suggests clinical relevance. We found that the activated AR directly interacts with miR-21 regulatory regions, indicating direct transcriptional induction. Furthermore, we provide new reporter studies supporting AR-regulation. Importantly, in functional studies, we found that a modest overexpression of miR-21 enhanced tumor xenograft growth and was sufficient to support androgen-independent proliferation following surgical castration. Thus, our studies suggest a model where miR-21 contributes to androgen-dependent and androgen-independent PCa growth. However, the AR is only one of many reported transcriptional regulators of miR-21. Here we review our recent discoveries and further analyze the reported miR-21 regulatory regions, inhibitory and stimulatory signaling pathways, and primary transcripts.

Discovery of prostate cancer biomarkers by microarray gene expression profiling

Prostate cancer is the most commonly diagnosed malignancy in males in the Western world. This review focuses on advances in biomarker discovery for prostate cancer by microarray profiling of mRNA and microRNA expression. Novel biomarkers are strongly needed to enable more accurate detection of prostate cancer, improve prediction of tumor aggressiveness and facilitate discovery of new therapeutic targets for tailored medicine. Promising molecular markers identified from gene expression profiling studies include AMACR, EZH2, TMPRSS2-ERG, miR-221 and miR-141, which are described in more detail. In addition, a compilation of prognostic gene expression signatures for prediction of prostate cancer patient outcome is provided, and their possible clinical utility is discussed. Furthermore, limitations in the application of microarray-based expression profiling for identification of prostate cancer biomarkers are addressed.

MicroRNA-224 is involved in transforming growth factor-beta-mediated mouse granulosa cell proliferation and granulosa cell function by targeting Smad4

Many members of the TGF-beta superfamily are indicated to play important roles in ovarian follicular development, such as affecting granulosa cell function and oocyte maturation. Abnormalities associated with TGF-beta1 signaling transduction could result in female infertility. MicroRNAs (miRNAs), as small noncoding RNAs, were recently found to regulate gene expression at posttranscriptional levels. However, little is known about the role of miRNAs in TGF-beta-mediated granulosa cell proliferation and granulosa cell function. In this study, the miRNA expression profiling was identified from TGF-beta1-treated mouse preantral granulosa cells (GCs), and three miRNAs were found to be significantly up-regulated and 13 miRNAs were down-regulated. Among up-regulated miRNAs, miR-224 was the second most significantly elevated miRNA. This up-regulation was attenuated by treatment of GCs with SB431542 (an inhibitor of TGFbeta superfamily type I receptors, thus blocking phosphorylation of the downstream effectors Smad2/3), indicating that miR-224 expression was regulated by TGF-beta1/Smads pathway. The ectopic expression of miR-224 can enhance TGF-beta1-induced GC proliferation through targeting Smad4. Inhibition of endogenous miR-224 partially suppressed GC proliferation induced by TGF-beta1. In addition, both miR-224 and TGF-beta1 can promote estradiol release from GC, at least in part, through increasing CYP19A1 mRNA levels. This is the first demonstration that miRNAs can control reproductive functions resulting in promoting TGF-beta1-induced GC proliferation and ovarian estrogen release. Such miRNA-mediated effects could be potentially used for regulation of reproductive processes or for treatment of reproductive disorders.

Evidence for gender-specific transcriptional profiles of nigral dopamine neurons in Parkinson disease

Background

Epidemiological data suggest that the male gender is one of the risks factors for the development of Parkinson Disease (PD). Also, differences in the clinical manifestation and the course of PD have been observed between males and females. However, little is known about the molecular aspects underlying gender-specificity in PD. To address this issue, we determined the gene expression profiles of male and female dopamine (DA) neurons in sporadic PD.

Methodology/Principal Findings

We analyzed Affymetrix-based microarrays on laser microdissected DA neurons from postmortem brains of sporadic PD patients and age-matched controls across genders. Pathway enrichment demonstrated that major cellular pathways involved in PD pathogenesis showed different patterns of deregulation between males and females with more prominent downregulation of genes related to oxidative phosporylation, apoptosis, synaptic transmission and transmission of nerve impulse in the male population. In addition, we found upregulation of gene products for metabolic processes and mitochondrial energy consumption in the age-matched male control neurons. On the single cell level, selected data validation using quantitative Real-Time (qRT)-PCR was consistent with microarray raw data and supported some of the observations from data analysis.

Conclusions/Significance

On the molecular level, our results provide evidence that the expression profiles of aged normal and PD midbrain DA neurons are gender-specific. The observed differences in the expression profiles suggest a disease bias of the male gender, which could be in concordance with clinical observations that the male gender represents a risk factor for sporadic PD. Validation of gene expression by qRT-PCR supported the microarray results, but also pointed to several caveats involved in data interpretation.

Impact of probe annotation on the integration of miRNA-mRNA expression profiles for miRNA target detection

MicroRNAs (miRNAs) are small non-coding RNAs that mediate gene expression at the post-transcriptional and translational levels by an imperfect binding to target mRNA 3′UTR regions. While the ab-initio computational prediction of miRNA–mRNA interactions still poses significant challenges, it is possible to overcome some of its limitations by carefully integrating into the analysis the paired expression profiles of miRNAs and mRNAs. In this work, we show how the choice of a proper probe annotation for microarray platforms is an essential requirement to achieve good sensitivity in the identification of miRNA–mRNA interactions. We compare the results obtained from the analysis of the same expression profiles using both gene and transcript based custom CDFs that we have developed for a number of different annotations (ENSEMBL, RefSeq, AceView). In all cases, transcript-based annotations clearly improve the effectiveness of data integration and thus provide a more reliable confirmation of computationally predicted miRNA–mRNA interactions.

MiRNA 26a expression in a novel panel of African American prostate cancer cell lines

INTRODUCTION

African American men have disproportionately high incidence and mortality rates of prostate cancer when compared to other ethnic groups in the United States. The identification of molecular factors that contribute to this disparity could improve diagnosis and therapeutic intervention. Therefore, the purpose of this study was to determine the miRNA 26a expression profile in novel African American and Caucasian prostate cell lines at each clinical stage of prostate cancer progression.

METHODS

The miR-26a expression profile was investigated using novel African American and Caucasian prostate cell lines representing each pathological stage: non-malignant, malignant, and metastatic tumors. Relative miRNA expression was determined by qRT-PCR.

RESULTS

Our data showed a 2.25 fold increase for miR-26a in the non-malignant, a 13.3 fold increase in malignant and 2.38 fold increase in metastatic tumors, when comparing African American and Caucasian prostate cell lines of similar clinical stage and pathological grade. African American malignant prostate cancer cell lines showed the most significant fold difference in expression among all cell lines tested. Furthermore, there was a general increase in miR-26a expression toward the more aggressive cell lines in both African American and Caucasian prostate cell lines.

CONCLUSION

To date, we are unaware of any studies that compare the miRNA profile at different stages of prostate cancer among two racial groups. Although a gene target for miR-26a has not been identified, our data show a possible role for miRNA regulation of gene expression in prostate cancer progression. Furthermore, this study suggests that miRNAs could possibly contribute to the aggressiveness associated in African American patients with prostate cancer.

The impact of perineural invasion on biochemical outcome after permanent prostate iodine-125 brachytherapy

PURPOSE

Perineural invasion (PNI) in prostate biopsies is associated with increased risk of higher Gleason score and worse pathologic stage. We report the influence of PNI in biochemical no evidence of disease (bNED) survival after (125)I prostate brachytherapy (BT).

METHODS AND MATERIALS

Pathology reports of 700 men with localized prostate cancer who underwent (125)I prostate BT in 1999-2008 were reviewed. The presence or absence of PNI in the biopsy was documented in 339 men. Clinical, treatment, and dosimetric parameters, along with PNI status, were evaluated for bNED survival, defined by "nadir+2" definition.

RESULTS

Of the 339 patients, 87% had favorable risk and 13% intermediate risk. PNI was present in 89 patients (26%). After a median followup of 32 months, there were five biochemical failures (4: +PNI and 1: -PNI), of which one was local failure (+PNI). Actuarial 5-year bNED survival for the entire group was 97.0% (92.9% for +PNI; 99.2% for -PNI). In univariate analysis age, pretreatment prostate-specific antigen, Gleason score 7, and intermediate risk group predicted for worse biochemical outcome, whereas the presence of PNI showed a trend toward significance (p=0.06). Some of the regression algorithms failed to converge because of low event rates.

CONCLUSIONS

We report excellent biochemical control in 339 men treated with (125)I prostate BT. The presence of PNI showed a trend toward significance in predicting 5-year bNED survival but did not impact on local control and should not influence the decision to recommend BT for localized prostate cancer.

mRNA and micro-RNA expression analysis in laser-capture microdissected prostate biopsies: valuable tool for risk assessment and prevention trials

Diagnosis of prostate cancer (PCa) typically relies on needle biopsies, which are routinely archived in paraffin after formalin fixation and may contain valuable risk or prognostic information. The objective of this study was to determine the feasibility of mRNA and miRNA expression analysis in laser-capture microdissected (LCM) formalin-fixed paraffin-embedded archived prostate biopsies compared to the gold standard of frozen tissue. We analyzed the expression of compartment-specific and PCa-related genes in epithelial and stromal tissues collected from paired sets of archived prostate biopsies and frozen radical prostatectomy specimens from three patients. Our results showed appropriate compartment-specific and PCa-related expression with good within patient agreement between the FFPE biopsies and the frozen tissue. The potential for both mRNA and micro-RNA expression profiling in the biopsies was also demonstrated using PCR arrays which showed high correlation between the biopsy and frozen tissue, notwithstanding sensitivity limitations for mRNA detection in the FFPE specimen. This is the first study to compare RNA expression from biopsy and frozen tissues from the same patient and to examine miRNA expression in LCM-collected tissue from prostate biopsies. With careful technique and use of appropriate controls, RNA profiling from archived biopsy material is quite feasible showing high correlation to frozen tissue.

Regulation of miRNA expression by Src and contact normalization: effects on nonanchored cell growth and migration

Transformation by the Src tyrosine kinase (Src) promotes nonanchored cell growth and migration. However, nontransformed cells can force Src-transformed cells to assume a normal morphology and phenotype by a process called 'contact normalization'. It has become clear that microRNA (miRNA) can affect tumorigenesis by targeting gene products that direct cell growth and migration. However, the roles of miRNA in Src transformation or contact normalization have not yet been reported. We examined the expression of 95 miRNAs and found 9 of them significantly affected by Src. In this study, we report that miR-218 and miR-224 were most significantly induced by Src, but not affected by contact normalization. In contrast, miR-126 was most significantly suppressed by Src and was induced by contact normalization in transformed cells. Mir-126 targets Crk, a component of the focal adhesion network that participates in events required for tumor cell migration. Accordingly, we show that miR-126 expression correlates inversely with Crk levels, motility and the invasive potential of human mammary carcinoma cells. Moreover, we show that miR-224 expression promotes nonanchored growth of nontransformed cells. These data reveal novel insights into how Src regulates miRNA expression to promote hallmarks of tumor cell growth and invasion, and how nontransformed cells can affect miRNA expression in adjacent tumor cells to inhibit this process.

Seeking unique and common biological themes in multiple gene lists or datasets: pathway pattern extraction pipeline for pathway-level comparative analysis

BACKGROUND

One of the challenges in the analysis of microarray data is to integrate and compare the selected (e.g., differential) gene lists from multiple experiments for common or unique underlying biological themes. A common way to approach this problem is to extract common genes from these gene lists and then subject these genes to enrichment analysis to reveal the underlying biology. However, the capacity of this approach is largely restricted by the limited number of common genes shared by datasets from multiple experiments, which could be caused by the complexity of the biological system itself.

RESULTS

We now introduce a new Pathway Pattern Extraction Pipeline (PPEP), which extends the existing WPS application by providing a new pathway-level comparative analysis scheme. To facilitate comparing and correlating results from different studies and sources, PPEP contains new interfaces that allow evaluation of the pathway-level enrichment patterns across multiple gene lists. As an exploratory tool, this analysis pipeline may help reveal the underlying biological themes at both the pathway and gene levels. The analysis scheme provided by PPEP begins with multiple gene lists, which may be derived from different studies in terms of the biological contexts, applied technologies, or methodologies. These lists are then subjected to pathway-level comparative analysis for extraction of pathway-level patterns. This analysis pipeline helps to explore the commonality or uniqueness of these lists at the level of pathways or biological processes from different but relevant biological systems using a combination of statistical enrichment measurements, pathway-level pattern extraction, and graphical display of the relationships of genes and their associated pathways as Gene-Term Association Networks (GTANs) within the WPS platform. As a proof of concept, we have used the new method to analyze many datasets from our collaborators as well as some public microarray datasets.

CONCLUSION

This tool provides a new pathway-level analysis scheme for integrative and comparative analysis of data derived from different but relevant systems. The tool is freely available as a Pathway Pattern Extraction Pipeline implemented in our existing software package WPS, which can be obtained at http://www.abcc.ncifcrf.gov/wps/wps_index.php.

MicroRNAs, ultraconserved genes and colorectal cancers

In this review we present some recent advances in understanding the roles of non-coding RNAs, including microRNAs and ultraconserved genes, in colorectal cancer and the way these advances can be translated for better cure of patients. MicroRNAs are a class of small RNAs that do not code for proteins and yet function as gene regulators. The deregulation of microRNA expression is involved in the initiation, progression, and dissemination of any type of human tumor. The underlying mechanisms of microRNA deregulation in human cancers are just starting to be understood. Germline and somatic mutations in microRNAs or polymorphisms in the messenger protein-coding RNAs targeted by microRNAs may also contribute to the tumor phenotype. Profiling microRNAs by various methods has identified signatures associated with the diagnosis, staging, progression, and prognosis of human colorectal cancers. Consequently, miRNAs have potential as diagnostic biomarkers and therapeutic targets in colorectal cancers. Ultraconserved genes represent a recently identified class of transcripts, mainly non-coding, that are highly conserved during evolution and can regulate miRNAs by direct interaction. Fingerprints of ultraconserved genes expression can classify cancers, including colorectal cancers, and ultraconserved genes may be involved in metastasis. Thus, having a clearer understanding of the mechanisms involved in the deregulation of non-coding RNAs in colorectal cancers is expected to contribute greatly to the development of new microRNA-based strategies for the diagnosis and treatment of patients.

Involvement of CD40 targeting miR-224 and miR-486 on the progression of pancreatic ductal adenocarcinomas

BACKGROUND

Genetic and epigenetic alterations during development of pancreatic ductal adenocarcinomas (PDAC) are well known. Genetic and epigenetic data were correlated with tumor biology to find specific alterations responsible for invasion and metastasis in pancreatic ductal adenocarcinomas.

METHODS

A total of 16 human PDAC cell lines were used in murine orthotopic PDAC models. By means of standardized dissemination scores, local invasion and metastatic spread were assessed. mRNA and microRNA expression were studied by microarray and TaqMan low-density array. Quantitative real-time-polymerase chain reaction and flow cytometry were used for expression validation.

RESULTS

CD40 was detected as a relevant target gene for differentially expressed miRNAs observed in highly invasive and metastatic PDAC only. A significant overexpression (P < .05) of CD40-related miRNAs miR-224 and miR-486 was detected in highly invasive and metastatic PDAC, whereas CD40 mRNA expression was not significantly altered. Instead, CD40 protein expression at cell surfaces of these highly invasive and metastatic PDAC was significantly reduced (P < .01).

CONCLUSIONS

Epigenetic alterations with upregulated CD40-targeting miR-224 and miR-486 are related to downregulated CD40 protein expression at cell surfaces in highly invasive and metastatic PDAC. Thus, miRNA-regulated CD40 expression seems to play an important role in progression of PDAC. These data suggest a diagnostic and therapeutic potential for CD40 and/or its targeting miRNAs in PDAC.

MicroRNA involvement in hepatocellular carcinoma

Hepatocellular carcinoma (HCC) is the third cause of cancer-related death worldwide. Curative options for HCC are limited and exclusively available for patients carrying an early stage HCC. In advanced stages, traditional chemotherapy proved to be only marginally effective or even toxic. Thus, the identification of new treatment options is needed. New targets for non-conventional treatment will necessarily take advantage of progresses on the molecular pathogenesis of HCC. MicroRNAs (miRNAs) are a group of tiny RNAs with a fundamental role in the regulation of gene expression. Aberrant expression of several miRNAs was found to be involved in human hepatocarcinogenesis. miRNA expression signatures were correlated with bio-pathological and clinical features of HCC. In some cases, aberrantly expressed miRNAs could be linked to cancer-associated pathways, indicating a direct role in liver tumourigenesis. For example, up-regulation of mir-221 and mir-21 could promote cell cycle progression, reduce cell death and favour angiogenesis and invasion. These findings suggest that miRNAs could become novel molecular targets for HCC treatment. The demonstration of in vivo efficacy and safety of anti-miRNA compounds has opened the way to their use in clinical trials.

Androgenic regulation of hedgehog signaling pathway components in prostate cancer cells

Hedgehog signaling is thought to play a role in several human cancers including prostate cancer. Although prostate cancer cells express many of the gene products involved in hedgehog signaling, these cells are refractory to the canonical signaling effects of exogenous hedgehog ligands or to activated Smoothened, the hedgehog-regulated mediator of Gli transcriptional activation. Here, we show that the expression of hedgehog ligands and some hedgehog target genes are regulated by androgen in the human prostate cancer cell line, LNCaP and its more metastatic variants (C4-2 and C4-2B). Androgen (R1881) strongly suppressed the expression of hedgehog ligands in these cells and their prolonged maintenance in androgen-deficient medium upregulated Sonic and Indian hedgehog mRNA and protein levels by up to 30,000-fold. Hedgehogs were released into the conditioned medium of androgen-deprived LNCaP cells and this medium was able to increase hedgehog target gene expression in hedgehog-responsive mouse fibroblasts (MC3T3-E1). Moreover, this activity was accompanied by increased expression of Gli target genes, Patched 1 and Gli2, in LNCaP that could be suppressed by cyclopamine, indicating that chronic androgen-deprivation also re-awakens the autocrine responsiveness of the cancer cells to hedgehog. In contrast to the suppressive effects of R1881 on hedgehog ligand and Gli2 expression, we found that Gli1 expression in LNCaP cells was induced by R1881. Given the ability of androgen to modulate the expression and release of hedgehog ligands and the activity of the autocrine hedgehog signaling pathway in these prostate cancer cells, our results imply that chronic androgen deprivation therapy (ADT) for prostate cancer might create a hedgehog signaling environment in the region of the tumor that could ultimately impact on the long term effectiveness of this treatment. This consideration supports the idea of clinically testing hedgehog-blocking drugs in conjunction with ADT in patients with advanced prostate cancer.

MicroRNA miR-155 is a biomarker of early pancreatic neoplasia

BACKGROUND

Intraductal papillary mucinous neoplasms (IPMNs) are non-invasive precursor lesions of pancreatic cancer. Misexpression of microRNAs (miRNAs) is commonly observed in pancreatic adenocarcinoma. In contrast, miRNA abnormalities in pancreatic cancer precursor lesions have not been documented.

EXPERIMENTAL DESIGN

Relative expression levels of a panel of twelve miRNAs upregulated in pancreatic cancers were assessed in 15 non-invasive IPMNs, using quantitative reverse transcription PCR (qRT-PCR). Two significantly overexpressed miRNAs-miR-155 and miR-21-were evaluated by locked nucleic acid in situ hybridization (LNA-ISH) in a panel of 64 archival IPMNs. The expression of miR-155 and miR-21 was also evaluated in pancreatic juice samples obtained from ten patients with surgically resected IPMNs and five patients with non-neoplastic pancreato-biliary disorders ("disease controls").

RESULTS

Significant overexpression by qRT-PCR of ten of the twelve miRNAs was observed in the 15 IPMNs versus matched controls (p < 0.05), with miR-155 (mean 11.6-fold) and miR-21 (mean 12.1-fold) demonstrating highest relative fold-changes in the precursor lesions. LNA-ISH confirmed the expression of miR-155 in 53 of 64 (83%) IPMNs compared to 4 of 54 (7%) normal ducts, and of miR-21 in 52 of 64 (81%) IPMNs compared to 1 of 54 (2%) normal ducts, respectively (p < 0.0001). Upregulation of miR-155 transcripts by qRT-PCR was observed in 6 of 10 (60%) IPMN-associated pancreatic juice samples compared to 0 of 5 (0%) disease controls.

CONCLUSIONS

Aberrant miRNA expression is an early event in the multistage progression of pancreatic cancer, and miR-155 warrants further evaluation as a biomarker for IPMNs in clinical samples.

MicroRNA miR-155 is a biomarker of early pancreatic neoplasia

BACKGROUND

Intraductal papillary mucinous neoplasms (IPMNs) are non-invasive precursor lesions of pancreatic cancer. Misexpression of microRNAs (miRNAs) is commonly observed in pancreatic adenocarcinoma. In contrast, miRNA abnormalities in pancreatic cancer precursor lesions have not been documented.

EXPERIMENTAL DESIGN

Relative expression levels of a panel of twelve miRNAs upregulated in pancreatic cancers were assessed in 15 non-invasive IPMNs, using quantitative reverse transcription PCR (qRT-PCR). Two significantly overexpressed miRNAs-miR-155 and miR-21-were evaluated by locked nucleic acid in situ hybridization (LNA-ISH) in a panel of 64 archival IPMNs. The expression of miR-155 and miR-21 was also evaluated in pancreatic juice samples obtained from ten patients with surgically resected IPMNs and five patients with non-neoplastic pancreato-biliary disorders ("disease controls").

RESULTS

Significant overexpression by qRT-PCR of ten of the twelve miRNAs was observed in the 15 IPMNs versus matched controls (p < 0.05), with miR-155 (mean 11.6-fold) and miR-21 (mean 12.1-fold) demonstrating highest relative fold-changes in the precursor lesions. LNA-ISH confirmed the expression of miR-155 in 53 of 64 (83%) IPMNs compared to 4 of 54 (7%) normal ducts, and of miR-21 in 52 of 64 (81%) IPMNs compared to 1 of 54 (2%) normal ducts, respectively (p < 0.0001). Upregulation of miR-155 transcripts by qRT-PCR was observed in 6 of 10 (60%) IPMN-associated pancreatic juice samples compared to 0 of 5 (0%) disease controls.

CONCLUSIONS

Aberrant miRNA expression is an early event in the multistage progression of pancreatic cancer, and miR-155 warrants further evaluation as a biomarker for IPMNs in clinical samples.

The RNA infrastructure: dark matter of the eukaryotic cell?

Eukaryotes express many functional non-protein-coding RNAs (ncRNAs) that participate in the processing and regulation of other RNA molecules. By focusing on connections between RNA-based processes, common patterns emerge that form a network-like RNA infrastructure. Owing to the intracellular movement of RNA during its processing (both between nuclear compartments and between the nucleus and cytoplasm), the RNA infrastructure contains both spatial and temporal connections. As research moves away from being protein-centric and focuses more on genomics, it is timely to explore these often 'hidden' aspects of the eukaryotic cell. The general and ancestral nature of most basic RNA-processing steps places a new focus on the generality of the spatial and temporal steps in RNA processing.

Expression profile of microRNA in epithelial cancer: diagnosis, classification and prediction

BACKGROUND

MicroRNAs (miRNAs), the small non-coding RNAs, regulate gene expression in a sequence-specific manner. Up to one-third of human messenger RNAs (mRNAs) appear to be miRNA targets. Each miRNA can target hundreds of mRNA transcripts and production of proteins directly or indirectly, while more than one miRNA can converge on a single transcript target. Therefore, potential regulatory circuitries afforded by miRNAs are enormous. Recent studies indicate that miRNAs act as key regulators of various fundamental biological processes, in which common pathways are shared with cancer.

OBJECTIVE/METHODS

To provide an overview of the potential application of miRNA profile in human epithelial cancer diagnosis, more than 180 miRNA-related publications have been reviewed.

CONCLUSION

Increasing evidence shows that the expression of miRNAs is remarkably deregulated in human cancer owing to multiple epigenetic and genomic alterations, and several miRNAs have been demonstrated to serve as tumor suppressor genes or oncogenes in cancer. The deregulated miRNA expression profile in human cancer may prove a powerful tool for cancer detection, diagnosis, classification and prognosis.

MicroRNAs and cancer: current state and future perspectives in urologic oncology

MicroRNAs (miRNAs) are small non-protein coding RNAs that regulate basic cellular processes and are associated with cancer characteristics. It is the aim of this review to describe the basics of the biogenesis and function of miRNAs, provide their role in tumorigenesis, and demonstrate their clinical potential in general and especially in urologic oncology. For that purpose, a PubMed search up to August 2008 was conducted using the Medical Subject Heading (MeSH) terms for miRNAs alone and the urological carcinomas of kidney, prostate, bladder, testis, and penis combined with the Boolean operator "AND". Until August 2008, about 3,500 miRNA publications were included in the PubMed database. It has been estimated that about 1,500 would be published in 2008 alone. Several miRNA expression studies and corresponding functional experiments in various cancers showed the important role of miRNAs in cancer initiation and progression and proved their potential as diagnostic, prognostic, and predictive biomarkers and as basis for novel therapeutic strategies. However, in uro-oncology, only a few miRNA related articles (22 for prostate, 4 for kidney, 3 for bladder, and 6 for testis) were published. Cancer-specific expressions of miRNA patterns were shown, but the limited and partly inconsistent data underscore that we are at an early stage regarding this topic in urology. In spite of the obvious significance of miRNAs in malignant tumors, the relatively sparse data on miRNAs in uro-oncology clearly advocate that this area should be more intensively studied. Detailed understanding of the characteristic miRNA abnormalities could contribute to novel approaches in diagnosis and treatment of urological tumors.

The inhibition of the highly expressed miR-221 and miR-222 impairs the growth of prostate carcinoma xenografts in mice

Background

MiR-221 and miR-222 are two highly homologous microRNAs whose upregulation has been recently described in several types of human tumors, for some of which their oncogenic role was explained by the discovery of their target p27, a key cell cycle regulator. We previously showed this regulatory relationship in prostate carcinoma cell lines in vitro, underlying the role of miR-221/222 as inducers of proliferation and tumorigenicity.

Methodology/Principal Findings

Here we describe a number of in vivo approaches confirming our previous data. The ectopic overexpression of miR-221 is able, per se, to confer a high growth advantage to LNCaP-derived tumors in SCID mice. Consistently, the anti-miR-221/222 antagomir treatment of established subcutaneous tumors derived from the highly aggressive PC3 cell line, naturally expressing high levels of miR-221/222, reduces tumor growth by increasing intratumoral p27 amount; this effect is long lasting, as it is detectable as long as 25 days after the treatment. Furthermore, we provide evidence in favour of a clinical relevance of the role of miR-221/222 in prostate carcinoma, by showing their general upregulation in patient-derived primary cell lines, where we find a significant inverse correlation with p27 expression.

Conclusions/Significance

These findings suggest that modulating miR-221/222 levels may have a therapeutic potential in prostate carcinoma.