MicroRNA expression aids the preoperative diagnosis of pancreatic ductal adenocarcinoma

MicroRNA-99 family in cancer: molecular mechanisms for clinical applications

MicroRNAs (miRNAs) are a class of non-coding RNA sequences that regulate gene expression post-transcriptionally. The miR-99 family, which is highly evolutionarily conserved, comprises three homologs: miR-99a, miR-99b, and miR-100. Its members are under-expressed in most cancerous tissues, suggesting their cancer-repressing properties in multiple cancers; however, in some contexts, they also promote malignant lesion progression. MiR-99 family members target numerous genes involved in various tumor-related processes such as tumorigenesis, proliferation, cell-cycle regulation, apoptosis, invasion, and metastasis. We review the recent research on this family, summarize its implications in cancer, and explore its potential as a biomarker and cancer therapeutic target. This review contributes to the clinical translation of the miR-99 family members.

Multi-omic markers of intraductal papillary mucinous neoplasms progression into pancreatic cancer

Pancreatic ductal adenocarcinoma (PDAC) is the most lethal and common form of pancreatic cancer, it has no specific symptoms, and most of the patients are diagnosed when the disease is already at an advanced stage. Chemotherapy typically has only a modest effect, making surgery the most effective treatment option. However, only a small percentage of patients are amenable to surgery. One viable strategy to reduce PDAC death burden associated with the disease is to focus on precursor lesions and identify markers able to predict who will evolve into PDAC. While most PDACs are believed to be preceded by pancreatic intraepithelial neoplasms (PanINs), 5-10 % arise from Intraductal papillary mucinous neoplasms (IPMNs), which are mass-forming cystic lesions that are very common in the general population. IPMNs offer an invaluable model of pancreatic carcinogenesis for researchers to analyse, as well as a target population for PDAC early detection by clinicians. The evolution of IPMN into cancer is a complex and multistep process, therefore the identification of individual markers will not be the solution. In recent years, multiple omics technologies have been instrumental to identify possible biomarkers of IPMN progression and carcinogenesis. The only foreseeable strategy will be to integrate multi-omics data, alongside clinical and morphological features, into a progression score or signature using either standard epidemiologic tools or artificial intelligence. The aim of this manuscript is to review the current knowledge on genetic biomarkers and to briefly mention also additional omics, such as metabolomics, the exposome, the miRNome and epigenomics of IPMNs.

Dual epigenetic changes in diabetes mellitus-associated pancreatic ductal adenocarcinoma correlate with downregulation of E-cadherin and worsened prognosis

Diabetes mellitus (DM) is a risk factor for pancreatic ductal adenocarcinoma (PDAC) that promotes the promoter methylation of CDH1. It is still unclear whether DM can exert other epigenetic effects, such as altering microRNA (miR) expression, in PDAC. The expression of miR-100-5p is known to be changed in DM patients and can suppress the expression of E-cadherin. In this study, the correlation between DM status and dual epigenetic changes was evaluated in PDAC specimens from patients who underwent radical surgical resection. A total of 132 consecutive patients with PDAC were clinicopathologically evaluated. E-cadherin and nuclear β-catenin expression was measured using immunohistochemistry. DNA and miRs were extracted from the main tumor site on formalin-fixed paraffin-embedded tissue sections. TaqMan miR assays were applied to assess miR-100-5p expression. Bisulfite modification was conducted on the extracted DNA, which was then subjected to methylation-specific polymerase chain reaction. Immunohistochemistry revealed that decreased E-cadherin expression and increased nuclear β-catenin expression were significantly associated with DM and poor tumor cell differentiation. The presence of long-duration DM (≥3 years)  was a significant factor contributing to CDH1 promoter methylation (p < 0.01), while miR-100-5p expression was proportionally correlated with the preoperative HbA1c level (R = 0.34, p < 0.01), but not the duration of DM. The subjects with high miR-100-5p expression and CDH1 promoter methylation showed the highest level of vessel invasion and prevalence of tumor size ≥30 mm. PDAC subjects with dual epigenetic changes showed poorer overall survival (OS) than those with a single epigenetic change. miR-100-5p expression ≥4.13 and CDH1 promoter methylation independently predicted poor OS and disease-free survival (DFS) in the multivariate analysis. OS and DFS worsened in DM subjects with both HbA1c ≥ 6.5% and DM duration ≥3 years. Thus, DM is associated with two modes of epigenetic change by independent mechanisms and worsens prognosis.

Pancreatic Cancer: Genetic Conditions and Epigenetic Alterations

BACKGROUND

Pancreatic cancer is a lethal proliferative disease driven by multiple genetic and epigenetic alterations. Microarrays and omics-based sequencing techniques are potent tools that have facilitated a broader understanding of the complex biological processes that drive pancreatic ductal adenocarcinoma (PDAC). In turn, these tools have resulted in the identification of novel disease markers, prognostic factors, and therapeutic targets. Herein, we provide a review of the genetic and epigenetic drivers of PDAC relative to recent discoveries that impact patient management.

METHODS

A review of PubMed, Medline, Clinical Key, and Index Medicus was conducted to identify literature from January 1995 to July 2022 that is related to PDAC genetics and epigenetics. Articles in Spanish and English were considered during selection.

RESULTS

Molecular, genetic, and epigenetic diagnostic tools, novel biomarkers, and promising therapeutic targets have emerged in the treatment of pancreatic cancer. The implementation of microarray technology and application of large omics-based data repositories have facilitated recent discoveries in PDAC. Multiple molecular analyses based on RNA interference have been instrumental in the identification of novel therapeutic targets for patients with PDAC. Moreover, microarrays and next-generation omics-based discoveries have been instrumental in the characterization of subtypes of pancreatic cancer, thereby improving prognostication and refining patient selection for available targeted therapies.

CONCLUSION

Advances in molecular biology, genetics, and epigenetics have ushered in a new era of discovery in the pathobiology of PDAC. Current efforts are underway to translate these findings into clinical tools and therapies to improve outcomes in patients with PDAC.

Diagnosis of Pancreatic Cancer Using miRNA30e Biosensor

This work describes miRNA-based electrochemical biosensor for detection of miRNA30e, a pancreatic cancer biomarker. The screen-printed gold electrode was functionalized using cysteine hydrochloride followed by immobilization of synthesized colloidal gold nanorods (10-12 nm diameter and 25-65 nm length). The gold nanorods modified electrode surface was amino functionalized for covalent attachment of single-stranded DNA probe against miRNA30e (miR30e). This platform was utilized for electrochemical measurements and response analysis of target miRNA30e. Electrochemical impedance spectroscopic measurements showed very poor sensitivity (13.51 Ω/µg/mL/cm²) using charge transfer resistance calibration plots. Cyclic voltammetry and differential pulse voltammetry-based miR30e quantification showed decreasing current response with increasing concentration of miR30e with detection range of 0.1 fg/mL-0.1 µg/mL (14.9 aM-14.9 nM). The sensitivity of DPV sensing (104.4 µA/µg/mL/cm²) was found to be 1.3 times higher than that of CV-based quantification (79.6 µA/µg/mL/cm²). miRNA-based biosensors have the potential of replacing current invasive, time consuming and technically difficult diagnostic procedures. Furthermore, the lower limit of detection of 14.9 aM miRNA30e makes it a promising tool for detection of cancer at early stages and hence increasing survival rate.

The role of circulating miRNAs and CA19-9 in pancreatic cancer diagnosis

Diagnosis and treatment of pancreatic ductal adenocarcinoma (PA) remains a challenge in clinical practice. The aim of this study was to assess the role of microRNAs (miRNAs-21, -23a, -100, -107, -181c, -210) in plasma and tissue as possible biomarkers in the diagnosis of PA. Samples of plasma (PAp-n = 13), pancreatic tumors (PAt-n = 18), peritumoral regions (PPT-n = 9) were collected from patients during the surgical procedure. The control group consisted of samples from patients submitted to pancreatic surgery for trauma or cadaveric organs (PC-n = 7) and healthy volunteers donated blood (PCp-n = 6). The expression profile of microRNAs was measured in all groups using RT-PCR, serum CA19-9 levels were determined in PA and PC. In tissue samples, there was a difference in the expression of miRNAs-21, -210 (p < 0.05) across the PAt, PC and PPT groups. The PAp showed overexpression of miRNAs-181c, -210 (p < 0.05) when compared to PCp. The combination of miRNAs-21, -210 tissue expression and serum CA19-9 showed 100% accuracy in the diagnosis of PA, as well as miR-181c expression in the plasma (PApxPCp). The expression of microRNAs in plasma proved to be a promising tool for a noninvasive detection test for PA, as well as further studies will evaluate the utility of microRNAs expression as biomarkers for prognostic and response to therapy in PA.

miR-181b-5p Promotes the Progression of Cholangiocarcinoma by Targeting PARK2 via PTEN/PI3K/AKT Signaling Pathway

This study combined with bioinformatics analysis and investigated the expression pattern of miR-181b-5p, as well as explored its role and mechanism in cholangiocarcinoma (CCA or CHOL). Several bioinformatics databases were used to analyze the expression of miR-181b and the enrichment of miR-181b in biological activities and biological pathways in CCA. The RT-qPCR analysis was used to examine the expression levels of miR-181b-5p. A receiver operation characteristics (ROC) curve analysis and the Kaplan-Meier survival assay were conducted to validate the diagnostic and prognostic implication of miR-181b-5p. Cell experiments were used to explore the possible functional role of miR-181b-5p in CCA progression. The bioinformatics assay was used to predict the target gene of miR-181b-5p and Western blot was used to confirm the related signaling pathway. The bioinformatics analysis results suggest that miR-181b-5p was highly expressed in cholangiocarcinoma and its expression was negatively related to PARK2 expression in CCA tissues. miR-181b-5p expression in the serum and tissues was upregulated and associated with lymph node metastasis and TNM stage. Increased expression of miR-181b-5p had relatively high diagnostic accuracy and showed poor prognosis in CCA patients. In addition, miR-181b-5p overexpression enhanced cell proliferation, migration, and invasion by targeting PARK2. Overexpression of miR-181b-5p activated the PI3K/AKT signaling pathway, while knockdown of miR-181b-5p suppressed the signaling pathway. Increased expression of miR-181b-5p in CCA may be a potential diagnostic or/and prognostic indicator for CCA patients. The present data indicated miR-181b-5p acted as an oncogene in CCA through promoting tumor cell proliferation, migration, and invasion of CCA via the PTEN/PI3K/AKT signaling pathway by targeting PARK2, which might be a promising therapeutic target or biomarker for CCA.

miR-3940-5p/miR-8069 ratio in urine exosomes is a novel diagnostic biomarker for pancreatic ductal adenocarcinoma

Despite the development of several therapeutic options, the prognosis of pancreatic cancer remains poor. One reason for this is the difficulty of diagnosing the disease at an early stage. For example, carbohydrate antigen (CA) 19-9, which is the most widely used biomarker for pancreatic cancer, cannot be used to detect the disease at early stages. Some studies have attempted to find novel biomarkers for pancreatic cancer. The aim of the present study was to find a novel diagnostic biomarker for pancreatic ductal adenocarcinoma (PDAC) in urine exosomes. Exosomes were isolated from urine and serum samples of patients with PDAC and control subjects, or culture media of cancer cell lines. MicroRNAs (miRNAs) were purified from exosomes. Novel biomarker candidates for PDCA were identisfied from urine exosome miRNA using expression profiling, and validated in a larger number of samples using 3D digital PCR. The results of a preliminary analysis of nine PDAC and seven control subjects revealed that the miR-3940-5p/miR-8069 ratio in urine exosomes was elevated in the patients with PDAC. Experiments using cultured cancer cell lines revealed that the elevation of the miR-3940-5p/miR-8069 ratio was specific for PDAC. Furthermore, the elevation of the miR-3940-5p/miR-8069 ratio in exosomes tended to be higher in the urine than in the serum of patients with PDAC. Validation experiments on 43 PDAC, 12 chronic pancreatitis and 25 control subjects demonstrated that the miR-3940-5p/miR-8069 ratio in urine exosomes was elevated in PDAC at a relatively early stage of the disease. When this ratio was used in combination with CA19-9 for the diagnosis of PDAC, the sensitivity and positive predictive value improved to 93.0 and 78.4%, respectively, when either of them was positive. Additionally, the positive predictive value reached 100% when both were positive. The negative predictive value also improved to 89.7% when both were negative. The miR-3940-5p/miR-8069 ratio in urine exosomes may be useful as a tool for the diagnosis of PDAC, particularly when used in combination with CA19-9.

New era for pancreatic endoscopic ultrasound: From imaging to molecular pathology of pancreatic cancer

With recent advances in molecular pathology and the development of new chemotherapy regimens, the knowledge of the molecular alterations of pancreatic ductal adenocarcinoma (PDAC) is becoming appealing for stratifying patients for prognosis and response to a defined treatment. Archival formalin-fixed, paraffin-embedded samples are a useful source of genomic deoxyribonucleic acid; nevertheless, most studies employed formalin-fixed, paraffin-embedded samples deriving from surgical specimens, which are therefore representative of <20% of PDAC patients. Indeed, the development of a reliable methodology for endoscopic ultrasound-guided tissue acquisition, stabilization, and analysis is crucial for the development of molecular markers for clinical use in order to achieve "personalized medicine". With the development of new needles, this technique is able to retrieve a high quantity and quality of PDAC tissue that can be used not only for diagnosis but also for mutational and transcriptome evaluations and for the development of primary cell or tissue cultures. In the present editorial, we discuss the current knowledge regarding the use of endoscopic ultrasound as a tool to obtain samples for molecular analyses, its possible pitfalls, and its use for the development of disease models such as xenografts or organoids.

Circulating microRNA-99 family as liquid biopsy marker in pancreatic adenocarcinoma

PURPOSE

Recently, we identified the microRNA-99 family as unfavorable prognostic factor in patients with pancreatic ductal adenocarcinoma (PDAC). The aim of this study is to evaluate its value as circulating biomarker for PDAC.

METHODS

Tissue and corresponding preoperative blood samples of 181 patients with PDAC UICC Stages I-IV (n = 90), intraductal papillary mucinous neoplasm (IPMN, n = 11), chronic pancreatitis (n = 40), pancreatic cystadenoma (n = 20), and age-matched healthy blood serum controls (n = 20) were collected between 2014 and 2017 prospectively. Expression of microRNA-21 as confirmatory marker and the microRNA-99 family, consisting of microRNA-99a, -99b, and -100, was analyzed by qRT-PCR. Target analysis of insulin-like growth factor 1 receptor (IGF1R) was performed using tissue array immunohistochemistry and Western blotting.

RESULTS

Expression of microRNA-99 family members was significantly increased in macrodissected tumor tissue and corresponding blood serum samples (p < 0.05) of patients with PDAC of all stages. Correspondingly, its target protein IGF1R was upregulated (p < 0.001) in carcinoma tissue. Circulating and tissue-related microRNA-100 could well discriminate PDAC from healthy samples with area under the receiver operating characteristic (ROC) curve (AUC) values of 0.81 and 0.85, respectively. Low expression of circulating microRNA-100 was associated with significantly improved overall survival (p = 0.004) and recurrence-free survival (p = 0.03) in multivariate analyses. Circulating microRNA-21 was overexpressed in PDAC with fair discrimination between PDAC and healthy controls (AUC = 0.71) and decreased overall survival (p = 0.046) and recurrence-free survival (p = 0.03) in PDAC patients.

CONCLUSIONS

Multivariate survival and ROC analyses identified circulating microRNA-100 as potential diagnostic and prognostic marker in PDAC patients.

Differential MicroRNA Expression between EGFR T790M and L858R Mutated Lung Cancer

Background

MicroRNAs (miRNAs) are short, non-coding RNAs that mediate post-transcriptional gene regulation. They are commonly deregulated in human malignancies, including non-small cell lung cancer (NSCLC). The aim of this study is to investigate miRNA expression in T790M-mutated NSCLC resistant to epidermal growth factor receptor (EGFR) tyrosine kinase inhibitors.

Methods

Six cases of resected NSCLC harboring the T790M mutation were examined. We performed miRNA time polymerase chain reaction (PCR) array profiling using EGFR T790M-mutated NSCLC and L858R-mutated NSCLC. Once identified, miRNAs that were differentially expressed between the two groups were validated by quantitative real-time polymerase chain reaction (qRT-PCR).

Results

miRNA PCR array profiling revealed three up-regulated miRNAs whose expression levels were altered 4.0-fold or more in the EGFR T790M mutation group than in the L858R group: miR-1 (fold change, 4.384), miR-196a (fold change, 4.138), and miR-124 (fold change, 4.132). The three differentially expressed miRNAs were validated by qRT-PCR, and they were found to be overexpressed in the T790M group relative to L858R group. In particular, expression levels of miR-1 and miR-124 were significantly higher in the T790M group (p-value of miR-1 = .004, miR-124 = .007, miR-196a = .096).

Conclusions

MiR-1, miR-124, and miR-196a are overexpressed in EGFR T790M mutated NSCLC.

Roles of microRNA in prostate cancer cell metabolism

MicroRNAs are non-coding RNA which functions as regulators of genes expression. MicroRNAs have shown their biological functions in cell proliferation, cell cycle, cell metabolism, apoptosis, invasion and metastasis. Cancer cells have the ability to grow in the absence of growth factors by increased metabolic activity. MicroRNAs regulate cell metabolic processes by targeting the key enzymes or transporters and change the metabolic activities by interfering with oncogenes/tumor suppressors, hypoxia, signalling pathways and cell adhesion. This review mainly explains the roles of microRNAs in prostate cancer cell metabolism, such as glucose uptake, glycolysis and lactate secretion, lipid metabolism and interaction with signalling pathways. The relation of microRNAs with hypoxia and cell adhesion in cell metabolism is also highlighted. Therefore, miRNAs help in regulating the metabolism of survived tumor cells, understanding such miRNA-mediated interaction could lead to new avenues in therapeutic application to treat PCa.

Plasma miRNAs in diagnosis and prognosis of pancreatic cancer: A miRNA expression analysis

The differential expression of microRNAs (miRNAs) in plasma of pancreatic cancer (PC) patients may act as a diagnostic biomarker. A four-stage study was performed to identify plasma miRNAs with potential in detecting PC. Exiqon panels (20 PC vs. 10 normal controls (NCs)) were applied in the screening phase to obtain miRNA profiling. The identified miRNAs were further assessed in the training (40 PC vs. 40 NCs) and testing stages (112 PC vs. 116 NCs) with qRT-PCR assays. A six-miRNA signature including up-regulated miR-122-5p, miR-125b-5p, miR-192-5p, miR-193b-3p, miR-221-3p and miR-27b-3p was identified. The signature could accurately discriminate PC patients from NCs with areas under the receiver operating characteristic curve of 0.848, 0.833 and 0.937 for the training, testing and the external validation stage (41 PC vs. 50 NCs), respectively. The multivariate Cox regression analyses showed that down-regulated plasma miR-125b-5p could predict worse OS independent from late tumor stage and high CA19-9. All the six miRNAs except miR-122-5p showed high expression levels in PC tissues than those in matched normal tissues. MiR-122-5p and miR-193b-3p were up-regulated, while miR-221-3p was down-regulated in plasma exosomes from PC patients. Bioinformatics analysis demonstrated that the miRNAs might involve in several molecular pathways closely related with PC such as p53 signaling pathway, pancreatic cancer, TGF-beta signaling pathway and so on. In conclusion, we identified a six-miRNA signature in plasma which could act as a non-invasive biomarker in diagnosis and prognosis of PC. Plasma miR-125b-5p might act as an independent biomarker in predicting OS of PC patients.

Systematic Review and Meta-Analysis of Diagnostic Accuracy of miRNAs in Patients with Pancreatic Cancer

Background

It is reported that miRNAs are aberrantly expressed in patients with pancreatic cancer. However, the diagnostic value of miRNAs in pancreatic cancer remains controversial. The meta-analysis was to access diagnostic accuracy of miRNAs in pancreatic cancer.

Methods

PubMed, Scopus, Web of Science, Chinese National Knowledge Infrastructure (CNKI), WANFANG Data, China Biomedical Literature Database (CBM), and VIP databases were retrieved up to June 30, 2016, to collect articles concerning the diagnosis of miRNAs in pancreatic cancer. The methodological quality of each study was assessed by the Quality Assessment of Diagnostic Accuracy Studies (QUADAS-2). This meta-analysis was conducted using RevMan5.0, MetaDiSc 1.4, and Stata 12.0 software.

Results

There are 40 articles including 109 studies. The pooled SEN was 0.81 (95% CI, 0.80–0.82), the pooled SPE was 0.78 (95% CI, 0.77–0.79), the pooled +LR was 3.32 (95% CI, 2.92–3.80), the pooled −LR was 0.27 (95% CI, 0.24–0.31), the pooled DOR was 14.56 (95% CI, 11.55–18.34), and pooled AUC was 0.86 (95% CI, 0.84–0.88).

Discussion

This meta-analysis demonstrated that miRNA makes a significant impact in the pancreatic cancer diagnosis with a high SEN and SPE, particularly using multiple miRNAs.

Tissue MicroRNA profiles as diagnostic and prognostic biomarkers in patients with resectable pancreatic ductal adenocarcinoma and periampullary cancers

Background

The aim of this study was to validate previously described diagnostic and prognostic microRNA expression profiles in tissue samples from patients with pancreatic cancer and other periampullary cancers.

Methods

Expression of 46 selected microRNAs was studied in formalin-fixed paraffin-embedded tissue from patients with resected pancreatic ductal adenocarcinoma (n = 165), ampullary cancer (n=59), duodenal cancer (n = 6), distal common bile duct cancer (n = 21), and gastric cancer (n = 20); chronic pancreatitis (n = 39); and normal pancreas (n = 35). The microRNAs were analyzed by PCR using the Fluidigm platform.

Results

Twenty-two microRNAs were significantly differently expressed in patients with pancreatic cancer when compared to healthy controls and chronic pancreatitis patients; 17 miRNAs were upregulated (miR-21-5p, −23a-3p, −31-5p, −34c-5p, −93-3p, −135b-3p, −155-5p, −186-5p, −196b-5p, −203, −205-5p, −210, −222-3p, −451, −492, −614, and miR-622) and 5 were downregulated (miR-122-5p, −130b-3p, −216b, −217, and miR-375). MicroRNAs were grouped into diagnostic indices of varying complexity. Ten microRNAs associated with prognosis were identified (let-7 g, miR-29a-5p, −34a-5p, −125a-3p, −146a-5p, −187, −205-5p, −212-3p, −222-5p, and miR-450b-5p). Prognostic indices based on differences in expression of 2 different microRNAs were constructed for pancreatic and ampullary cancer combined and separately (30, 5, and 21 indices).

Conclusion

The study confirms that pancreatic cancer tissue has a microRNA expression profile that is different from that of other periampullary cancers, chronic pancreatitis, and normal pancreas. We identified prognostic microRNAs and microRNA indices that were associated with shorter overall survival in patients with radically resected pancreatic cancer.

Electronic supplementary material

The online version of this article (doi:10.1186/s40364-017-0087-6) contains supplementary material, which is available to authorized users.

The Role of microRNAs in the Diagnosis and Treatment of Pancreatic Adenocarcinoma

Pancreatic ductal adenocarcinoma (PDAC) remains a very challenging malignancy. Disease is diagnosed in an advanced stage in the vast majority of patients, and PDAC cells are often resistant to conventional cytotoxic drugs. Targeted therapies have made no progress in the management of this disease, unlike other cancers. microRNAs (miRs) are small non-coding RNAs that regulate the expression of multitude number of genes by targeting their 3'-UTR mRNA region. Aberrant expression of miRNAs has been linked to the development of various malignancies, including PDAC. In PDAC, a series of miRs have been defined as holding promise for early diagnostics, as indicators of therapy resistance, and even as markers for therapeutic response in patients. In this mini-review, we present an update on the various different miRs that have been defined in PDAC biology.

Prospective validation of microRNA signatures for detecting pancreatic malignant transformation in endoscopic-ultrasound guided fine-needle aspiration biopsies

BACKGROUND

Pancreatic ductal adenocarcinoma (PDAC) is a lethal disease. Novel biomarkers are required to aid treatment decisions and improve patient outcomes. MicroRNAs (miRNAs) are potentially ideal diagnostic biomarkers, as they are stable molecules, and tumour and tissue specific.

RESULTS

Logistic regression analysis revealed an endoscopic-ultrasound fine-needle aspiration (EUS-FNA) 2-miRNA classifier (miR-21 + miR-155) capable of distinguishing benign from malignant pancreatic lesions with a sensitivity of 81.5% and a specificity of 85.7% (AUC 0.930). Validation FNA cohorts confirmed both miRNAs were overexpressed in malignant disease, while circulating miRNAs performed poorly.

METHODS

Fifty-five patients with a suspicious pancreatic lesion on cross-sectional imaging were evaluated by EUS-FNA. At echo-endoscopy, the first part of the FNA was sent for cytological assessment and the second part was used for total RNA extraction. Candidate miRNAs were selected after careful review of the literature and expression was quantified by qRT-PCR. Validation was performed on an independent cohort of EUS-FNAs, as well as formalin-fixed paraffin embedded (FFPE) and plasma samples.

CONCLUSIONS

We provide further evidence for using miRNAs as diagnostic biomarkers for pancreatic malignancy. We demonstrate the feasibility of using fresh EUS-FNAs to establish miRNA-based signatures unique to pancreatic malignant transformation and the potential to enhance risk stratification and selection for surgery.

Understanding the CREB1-miRNA feedback loop in human malignancies

cAMP response element binding protein 1 (CREB1, CREB) is a key transcription factor that mediates transcriptional responses to a variety of growth factors and stress signals. CREB1 has been shown to play a critical role in development and progression of tumors. MicroRNAs (miRNAs) are a class of non-coding RNAs. They post-transcriptionally regulate gene expression through pairing with the 3'-UTR of their target mRNAs and thus regulate initiation and progression of various types of human cancers. Recent studies have demonstrated that a number of miRNAs can be transcriptionally regulated by CREB1. Interestingly, CREB1 expression can also be modulated by miRNAs, thus forming a feedback loop. This review outlines the functional roles of CREB1, miRNA, and their interactions in human malignancies. This will help to define a relationship between CREB1 and miRNA in human cancer and develop novel therapeutic strategies.

Tumor-suppressive miR-99a inhibits cell proliferation via targeting of TNFAIP8 in osteosarcoma cells

Osteosarcoma (OS) has been described as the most common primary malignant bone tumor in adolescents and young adults worldwide. MicroRNAs (miRNAs) have demonstrated playing critical role on the cellular biology and development of cancer. However, the essential mechanisms of miRNAs underlying osteosarcoma oncogenesis and progression have not fully understood. In this study, we found that the expression of miR-99a was repressed in OS tissues and cells using qRT-PCR assays. We demonstrated that overexpression of miR-99a inhibits OS cell viability and growth with MTT, colony formation and in vivo mice experiment. In addition, FACS and Annexin V assays identified that miR-99a can induce OS cell cycle progression and cell apoptosis. Furthermore, we demonstrated that TNFAIP8 is a direct target of miR-99a and is upregulated in OS samples and cells. Knockdown of TNFAIP8 significantly attenuated OS cell viability and growth through inhibiting cell cycle and inducing cell apoptosis in vitro and in vivo. These findings establish that miR-99a plays a significant tumor-suppressing role in OS and proposes it as a potential diagnostic and therapeutic target in managing OS metastases.

MicroRNA Targeted Therapeutic Approach for Pancreatic Cancer

Pancreatic cancer remains the fourth leading cause of cancer-related death in the US and is expected to be the second leading cause of cancer-related death by 2030. Therefore, it is important to better understand the molecular pathogenesis, phenotypes and features of pancreatic cancer in order to design novel molecularly targeted therapies for achieving better therapeutic outcome of patients with pancreatic cancer. Recently, the roles of microRNAs (miRNAs) in the development and progression of pancreatic cancer became a hot topic in the scientific community of pancreatic cancer research. By conducting miRNA expression profiling, the aberrant expression of miRNAs was revealed in the serum and in cancer tissues from patients with pancreatic cancer. These aberrantly expressed miRNAs are critically correlated with the disease stage, drug resistance, and survival of pancreatic cancer patients. Hence, targeting these tiny molecules, the specific miRNAs, could provide an efficient and optimal approach in the therapy of pancreatic cancer. Indeed, the pre-clinical and in vivo experiments showed that nanoparticle delivery of synthetic oligonucleotides or treatment with natural agents could be useful to modulate the expression of miRNAs and thereby inhibit pancreatic cancer growth and progression, suggesting that targeting miRNAs combined with conventional anti-cancer therapeutics could be a novel therapeutic strategy for increasing drug sensitivity and achieving better therapeutic outcome of patients diagnosed with pancreatic cancer.

MicroRNA-183-5p promotes the proliferation, invasion and metastasis of human pancreatic adenocarcinoma cells

The aim of the current study was to investigate the potential role of microRNA-183-5p (miR-183-5p) in the proliferation, invasion and metastasis of pancreatic cancer, and to identify promising target genes of oncogenic miR-183-5p. Western blotting and quantitative polymerase chain reaction (qPCR) were used to investigate whether these oncogenic microRNAs may be useful as biomarkers in pancreatic carcinoma (PaCa). Potential target genes were verified using miRDB, PicTar and TargetSCAN, and qPCR was used to detect the expression of miR-183 and suppressor of cytokine signaling 6 (SOCS-6; a potential target of miR-183) in PANC-1 PaCa cells and in the HPDE6-C7 pancreatic ductal cell line for comparison. The function of miR-183 in cell proliferation, wound healing, invasion and migration was also investigated using a miR-183 inhibitor. Western blot analysis was used to confirm SOCS-6 as a tumor suppressor and qPCR was used to detect and confirm that this potential target gene is directly regulated by miR-183. The results indicated that the expression of miR-183 in PANC-1 cells was upregulated compared with that in HPDE6-C7 cells, whilst the expression of SOCS-6 was downregulated. SOCS-6 expression was also significantly lower in PaCa tissues compared with that in matched normal pancreatic tissues from PaCa patients. Furthermore, expression of miR-183 was inversely correlated with that of SOCS-6. miR-183 knockdown decreased cell growth and motility in pancreatic cancer cells and significantly increased the expression of SOCS-6. These data suggest that oncogenic miR-183 may be useful as a pancreatic cancer biomarker. In addition, inhibition of miR-183 expression may be beneficial as PaCa treatment. SOCS-6 is a potential target gene of miR-183.

Contribution of microRNA analysis to characterisation of pancreatic lesions: a review

Pancreatic tumours are usually very aggressive cancer with a poor prognosis. A limitation of pancreatic imaging techniques is that lesions are often of ambiguous relevance. The inability to achieve a definitive diagnosis based on cytological evaluation of specimens, due to sampling error, paucicellular samples or coexisting inflammation, might lead to delay in clinical management. Given the morbidity associated with pancreatectomy, a proper selection of patients for surgery is fundamental. Many studies have been conducted in order to identify specific markers that could support the early diagnosis of pancreatic lesions, but, to date, none of them allow to diagnose pancreatic cancer with high sensitivity and specificity. MicroRNAs (miRNA) are small non-coding RNAs (19-25 nucleotides) that regulate gene expression interacting with mRNA targets. It is now established that each tissue shows a characteristic miRNA expression pattern that could be modified in association with a number of different diseases including neoplasia. Due to their key role in the regulation of gene expression, in the last years several studies have investigated miRNA tissue-specific expression, quantification and functional analysis to understand their peculiar involvement in cellular processes. The aim of this review is to focus on miRNA expression in pancreatic cancer and their putative role in early characterisation of pancreatic lesions.

MicroRNA expression profiling of diagnostic needle aspirates from surgical pancreatic cancer specimens

Purpose

MicroRNAs (miRNAs) have been widely investigated as potential biomarkers for several malignancies. To establish the feasibility of miRNA expression profiling of small biopsy samples of pancreatic cancers, we assessed expression profiles in freshly collected aspirates obtained immediately after surgical resection of the pancreas.

Methods

We used separate fine needles (20-23 gauge) to aspirate the pancreatic cancer and adjacent normal pancreatic tissue. miRNAs that were differentially expressed in pancreatic cancers and matched paraneoplastic normal pancreatic tissues were identified using an miRNA microarray.

Results

We identified 158 aberrantly expressed miRNAs in pancreatic cancers; 51 were overexpressed and 107 underexpressed compared with normal pancreatic tissue. To confirm the microarray findings, quantitative RT-PCR was performed on individual samples. We chose eight miRNAs for further analysis; of which five were overexpressed (miR-21, miR-27a, miR-146a, miR-200a, and miR-196a) and three underexpressed (miR-217, miR-20a, and miR-96) in pancreatic cancer samples compared to benign pancreatic tissue. Expression of miR-21, miR-27a, miR-146a, miR-200a, and miR-196a was significantly increased in cancer fine-needle aspirates relative to matched controls in all samples. Expression of miR-217, miR-20a, and miR-96 was significantly downregulated in almost all pancreatic cancer tissues.

Conclusion

We demonstrate the feasibility of performing miRNA profiling on very small specimens obtained using fine-needle aspiration of pancreatic cancers.

MicroRNA-100 regulates pancreatic cancer cells growth and sensitivity to chemotherapy through targeting FGFR3

We intended to investigate the role of microRNA 100 (miR-100) in regulating pancreatic cancer cells' growth in vitro and tumor development in vivo. QTR-PCR was used to examine the expression of miR-100 in pancreatic cancer cell lines and tumor cells from human patients. Lentivirual vector containing miR-100 mimics (lv-miR-100) was used to overexpress miR-100 in MIA PaCa-2 and FCPAC-1 cells. The effects of overexpressing miR-100 on pancreatic cancer cell proliferation and chemosensitivity to cisplatin were examined by cell proliferation essay in vitro. MIA PaCa-2 cells with endogenously overexpressed miR-100 were transplanted into null mice to examine tumor growth in vivo. The predicted target of miR-100, fibroblast growth factor receptor 3 (FGFR3), was downregulated by siRNA to examine its effect on pancreatic cancer cells. We found miR-100 was markedly underexpressed in both pancreatic cancer cell lines and tumor cells from patients. In cancer cells, transfection of lv-miR-100 was able to upregulate endogenous expression of miR-100, inhibited cancer cell proliferation, and increased sensitivities to cisplatin. Overexpressing miR-100 led to significant inhibition on tumor formation in vivo. Luciferase essay showed FGFR3 was direct target of miR-100. FGFR3 was significantly downregulated by overexpressing miR-100 in pancreatic cancer cells and knocking down FGFR3 by siRNA exerted similar effect as miR-100. Our study demonstrated that miR-100 played an important role in pancreatic cancer development, possibly through targeting FGFR3. It may become a new therapeutic target for gene therapy in patients suffered from pancreatic cancer.

MicroRNA-100 regulates pancreatic cancer cells growth and sensitivity to chemotherapy through targeting FGFR3

We intended to investigate the role of microRNA 100 (miR-100) in regulating pancreatic cancer cells' growth in vitro and tumor development in vivo. QTR-PCR was used to examine the expression of miR-100 in pancreatic cancer cell lines and tumor cells from human patients. Lentivirual vector containing miR-100 mimics (lv-miR-100) was used to overexpress miR-100 in MIA PaCa-2 and FCPAC-1 cells. The effects of overexpressing miR-100 on pancreatic cancer cell proliferation and chemosensitivity to cisplatin were examined by cell proliferation essay in vitro. MIA PaCa-2 cells with endogenously overexpressed miR-100 were transplanted into null mice to examine tumor growth in vivo. The predicted target of miR-100, fibroblast growth factor receptor 3 (FGFR3), was downregulated by siRNA to examine its effect on pancreatic cancer cells. We found miR-100 was markedly underexpressed in both pancreatic cancer cell lines and tumor cells from patients. In cancer cells, transfection of lv-miR-100 was able to upregulate endogenous expression of miR-100, inhibited cancer cell proliferation, and increased sensitivities to cisplatin. Overexpressing miR-100 led to significant inhibition on tumor formation in vivo. Luciferase essay showed FGFR3 was direct target of miR-100. FGFR3 was significantly downregulated by overexpressing miR-100 in pancreatic cancer cells and knocking down FGFR3 by siRNA exerted similar effect as miR-100. Our study demonstrated that miR-100 played an important role in pancreatic cancer development, possibly through targeting FGFR3. It may become a new therapeutic target for gene therapy in patients suffered from pancreatic cancer.

A microRNA-based test improves endoscopic ultrasound-guided cytologic diagnosis of pancreatic cancer

BACKGROUND & AIMS

Endoscopic ultrasound-guided fine-needle aspiration (EUS-FNA) in combination with cytopathology is the optimal method for diagnosis and staging of pancreatic ductal adenocarcinoma (PDAC) and other pancreatic lesions. Its clinical utility, however, can be limited by high rates of indeterminate or false-negative results. We aimed to develop and validate a microRNA (miRNA)-based test to improve preoperative detection of PDAC.

METHODS

Levels of miRNAs were analyzed in a centralized clinical laboratory by relative quantitative polymerase chain reaction in 95 formalin-fixed paraffin-embedded specimens and 228 samples collected by EUS-FNA during routine evaluations of patients with solid pancreatic masses at 4 institutions in the United States, 1 in Canada, and 1 in Poland.

RESULTS

We developed a 5-miRNA expression classifier, consisting of MIR24, MIR130B, MIR135B, MIR148A, and MIR196, that could identify PDAC in well-characterized, formalin-fixed, paraffin-embedded specimens. Detection of PDAC in EUS-FNA samples increased from 78.8% by cytology analysis alone (95% confidence interval, 72.2%-84.5%) to 90.8% when combined with miRNA analysis (95% confidence interval, 85.6%-94.5%). The miRNA classifier correctly identified 22 additional true PDAC cases among 39 samples initially classified as benign, indeterminate, or nondiagnostic by cytology. Cytology and miRNA test results each were associated significantly with PDAC (P < .001), with positive predictive values greater than 99% (95% confidence interval, 96%-100%).

CONCLUSIONS

We developed and validated a 5-miRNA classifier that can accurately predict which preoperative pancreatic EUS-FNA specimens contain PDAC. This test might aid in the diagnosis of pancreatic cancer by reducing the number of FNAs without a definitive adenocarcinoma diagnosis, thereby reducing the number of repeat EUS-FNA procedures.

MicroRNA expression in salivary supernatant of patients with pancreatic cancer and its relationship with ZHENG

In traditional Chinese medicine (TCM), diagnosis and prescriptions are based on the signs and symptoms which are recognized as ZHENG. The cornerstone of TCM is to differentially treat one ZHENG from others, which is also known as syndrome differentiation, and this relies on the gathering of clinical information through inspection, auscultation and olfaction, inquiry, and palpation. However, the biomolecular basis of the ZHENG remains unclear. In this study, the expressions of 384 cancer-related miRNAs in salivary supernatant of patients with pancreatic cancer were assessed by miRNA polymerase chain reaction (PCR) array, and the different expression patterns of miRNA in three different groups of ZHENG were studied with use of real-time quantitative PCR (qRT-PCR). Some miRNAs were found to be specifically expressed in some ZHENGs, for instance, miR-17, miR-21, and miR-181b in Shi-Re ZHENG and miR-196a in Pi-Xu ZHENG. This indicates that these miRNAs may play important roles in different ZHENG condition. Therefore, this study to some extent revealed the molecular basis of TCM ZHENG in pancreatic cancer.

Aberrant MicroRNAs in Pancreatic Cancer: Researches and Clinical Implications

Pancreatic ductal adenocarcinoma (PDAC) is an aggressive malignancy with a high rate of mortality and poor prognosis. Numerous studies have proved that microRNA (miRNA) may play a vital role in a wide range of malignancies, including PDAC, and dysregulated miRNAs, including circulating miRNAs, are associated with PDAC proliferation, invasion, chemosensitivity, and radiosensitivity, as well as prognosis. Greater understanding of the roles of miRNAs in PDAC could provide insights into this disease and identify potential diagnostic markers and therapeutic targets. The current review focuses on recent advances with respect to the roles of miRNAs in PDAC and their practical value.

miR-181b as a key regulator of the oncogenic process and its clinical implications in cancer (Review)

MicroRNAs (miRNAs or miRs) are small, non-coding, single-stranded RNA molecules that regulate gene expression at the post-transcriptional level to repress protein expression of target genes. Among these, miR-181b has been found to be a critical regulatory miRNA linking inflammation and cancer. The functional significance of miR-181b in various tumors and translational research suggests that it exhibits great potential as a predictive and prognostic biomarker. Extensive efforts are underway to identify mRNA targets and the affected regulatory networks, which may be the key to providing a better understanding of miR-181b-mediated signaling pathways.

Down-regulation of miR-221 inhibits proliferation of pancreatic cancer cells through up-regulation of PTEN, p27(kip1), p57(kip2), and PUMA

Pancreatic cancer is the fourth leading cause of cancer related death in the US and exhibits aggressive features with short survival rate and high mortality. Therefore, it is important to understand the molecular mechanism(s) involved in the aggressive growth of pancreatic cancers, and further design novel targeted therapies for its treatment with better treatment outcome. In the present study, we found that the expression of miR-221 was significantly up-regulated in pancreatic cancer cell lines and tumor tissues compared to normal pancreatic duct epithelial cells and normal pancreas tissues. Moreover, we found that the pancreatic cancer patients with high miR-221 expression had a relatively shorter survival compared to those with lower expression, suggesting that miR-221 could be an oncogenic miRNA and a prognostic factor for poor survival of patients. Interestingly, transfection of miR-221 inhibitor suppressed the proliferative capacity of pancreatic cancer cells with concomitant up-regulation of PTEN, p27(kip1), p57(kip2), and PUMA, which are the tumor suppressors and the predicted targets of miR-221. Most importantly, we found that the treatment of pancreatic cancer cells with isoflavone mixture (G2535), formulated 3,3'-diindolylmethane (BR-DIM), or synthetic curcumin analogue (CDF) could down-regulate the expression of miR-221 and consequently up-regulate the expression of PTEN, p27(kip1), p57(kip2), and PUMA, leading to the inhibition of cell proliferation and migration of MiaPaCa-2 and Panc-1 cells. These results provide experimental evidence in support of the oncogenic role of miR-221 and also demonstrate the role of isoflavone, BR-DIM, and CDF as potential non-toxic agents that are capable of down-regulation of miR-221. Therefore, these agents combined with conventional chemotherapeutics could be useful in designing novel targeted therapeutic strategy for the treatment of pancreatic cancer for which there is no curative therapy.

Candidate microRNA biomarkers of pancreatic ductal adenocarcinoma: meta-analysis, experimental validation and clinical significance

BACKGROUND

The diagnostic and prognostic value of microRNA (miRNA) expression aberrations in pancreatic ductal adenocarcinoma (PDAC) has been studied extensively in recent years. However, differences in measurement platforms and lab protocols as well as small sample sizes can render gene expression levels incomparable.

METHODS

A comprehensive meta-review of published studies in PDAC that compared the miRNA expression profiles of PDAC tissues and paired neighbouring noncancerous pancreatic tissues was performed to determine candidate miRNA biomarkers for PDAC. Both a miRNA vote-counting strategy and a recently published Robust Rank Aggregation method were employed. In this review, a total of 538 tumour and 206 noncancerous control samples were included.

RESULTS

We identified a statistically significant miRNA meta-signature of seven up- and three down-regulated miRNAs. The experimental validation results showed that the miRNA expression levels were in accordance with the meta-signature. The results from the vote-counting strategy were consistent with those from the Robust Rank Aggregation method. The experimental validation confirmed that the statistically unique profiles identified by the meta-review approach could discriminate PDAC tissues from paired nonmalignant pancreatic tissues. In a cohort of 70 patients, the high expression of miR-21 (p=0.018, HR=2.610; 95% CI=1.179-5.777) and miR-31 (p=0.039, HR=2.735; 95% CI=1.317-6.426), the low expression of miR-375 (p=0.022, HR=2.337; 95% CI=1.431-5.066) were associated with poor overall survival following resection, independent of clinical covariates.

CONCLUSIONS

The identified miRNAs may be used to develop a panel of diagnostic and prognostic biomarkers for PDAC with sufficient sensitivity and specificity for use in a clinical setting.

Role of epithelial-mesenchymal transition in pancreatic ductal adenocarcinoma: is tumor budding the missing link?

Pancreatic ductal adenocarcinoma (PDAC) ranks as the fourth commonest cause of cancer death while its incidence is increasing worldwide. For all stages, survival at 5 years is<5%. The lethal nature of pancreatic cancer is attributed to its high metastatic potential to the lymphatic system and distant organs. Lack of effective therapeutic options contributes to the high mortality rates of PDAC. Recent evidence suggests that epithelial-mesenchymal transition (EMT) plays an important role to the disease progression and development of drug resistance in PDAC. Tumor budding is thought to reflect the process of EMT which allows neoplastic epithelial cells to acquire a mesenchymal phenotype thus increasing their capacity for migration and invasion and help them become resistant to apoptotic signals. In a recent study by our own group the presence and prognostic significance of tumor budding in PDAC were investigated and an association between high-grade budding and aggressive clinicopathological features of the tumors as well as worse outcome of the patients was found. The identification of EMT phenotypic targets may help identifying new molecules so that future therapeutic strategies directed specifically against them could potentially have an impact on drug resistance and invasiveness and hence improve the prognosis of PDAC patients. The aim of this short review is to present an insight on the morphological and molecular aspects of EMT and on the factors that are involved in the induction of EMT in PDAC.

MicroRNAs as diagnostic markers for pancreatic ductal adenocarcinoma and its precursor, pancreatic intraepithelial neoplasm

Since the discovery of small non-coding RNAs, the analysis of microRNA (miRNA) expression patterns in human cancer have provided new insights into cancer biology. Evidence suggests that deregulated miRNA expression is associated with pancreatic cancer development. In this study, we analyzed the expression of several miRNAs in different types of pancreatic disease to determine if miRNA expression could aid in the diagnosis of pancreatic ductal adenocarcinoma (PDAC) and its precursor, pancreatic intraepithelial neoplasm (PanIN). Pancreatic resection specimens were selected, which included PDAC (n = 16), benign pancreatic parenchyma from corresponding carcinoma cases (n = 16), chronic pancreatitis (n = 4), normal pancreatic parenchyma (n = 5), and PanIN (n = 5). The expression levels of five miRNA (miR-148a, miR-217, miR-21, miR-196a, and miR-10b) were assessed by quantitative real-time reverse transcription-polymerase chain reaction (qRT-PCR) assays. Our data demonstrate that compared to the normal pancreatic parenchyma, miR-148a and miR-217 expression levels were down-regulated in PanIN, particularly in PanIN II-III and PDAC, whereas the level of miR-196 was significantly up-regulated in PDAC and its precursor, PanIN II-III. In addition, we observed that miR-21 was significantly overexpressed in PDAC, and miR-10b was highly expressed in PanIN II-III. Our study demonstrates that certain miRNAs, especially miR-148a, miR-217, and miR-196a, are significantly deregulated in PDAC, including in the early stage of PDAC. These markers can potentially be used as diagnostic markers to distinguish PDAC and its precursor from benign lesions.

Regulation of miR-155 affects pancreatic cancer cell invasiveness and migration by modulating the STAT3 signaling pathway through SOCS1

In the present study, we investigated the effects of miR-155 on pancreatic cancer cell invasion and migration in vitro, underlying gene expression, expression of miR-155 and its target genes in pancreatic cancer tissues, and their association with metastasis and clinical stage. miR-155 mimics and an inhibitor were transfected into Panc-1 and Capan-2 cells in order to regulate the expression of miR-155. qPCR and western immunoblotting were performed in order to detect gene expression. Transwell assays were performed to characterize the invasion and migration of pancreatic cancer cells in vitro. Immunohistochemical analysis and in situ hybridization were used to detect the expression of protein and microRNA in pancreatic cancer tissue. miR-155 mimics and an inhibitor upregulated and downregulated, respectively, the expression of miR-155 in pancreatic cancer cells. The invasion and migration of pancreatic cancer cells increased or decreased along with miR-155 expression in vitro. Suppressor of cytokine signaling 1 (SOCS1) protein expression was upregulated when miR-155 was inhibited and downregulated when miR-155 was increased. However, the expression of P-signal transducer and activator of transcription-3 (STAT3) was synchronized with that of miR-155. Transcription of SOCS1 and STAT3 was unchanged by miR-155 regulation. miR-155 expression was high in pancreatic cancer tissues and SOCS1 expression was high in tumor-adjacent tissues. There was no relationship between these genes in cancer and tumor-adjacent tissues. In addition, miR-155 expression was associated with lymph node metastasis and clinical stage. In conclusion, miR-155 plays an important role in the regulation of pancreatic cancer cell invasion and migration by modulating the STAT3 signaling pathway and reducing SOCS1 expression in pancreatic cancer cells.

miRConnect 2.0: identification of oncogenic, antagonistic miRNA families in three human cancers

BACKGROUND

Based on their function in cancer micro(mi)RNAs are often grouped as either tumor suppressors or oncogenes. However, miRNAs regulate multiple tumor relevant signaling pathways raising the question whether two oncogenic miRNAs could be functional antagonists by promoting different steps in tumor progression. We recently developed a method to connect miRNAs to biological function by comparing miRNA and gene array expression data from the NCI60 cell lines without using miRNA target predictions (miRConnect).

RESULTS

We have now extended this analysis to three primary human cancers (ovarian cancer, glioblastoma multiforme, and kidney renal clear cell carcinoma) available at the Cancer Genome Atlas (TCGA), and have correlated the expression of the clustered miRNAs with 158 oncogenic signatures (miRConnect 2.0). We have identified functionally antagonistic groups of miRNAs. One group (the agonists), which contains many of the members of the miR-17 family, correlated with c-Myc induced genes and E2F gene signatures. A group that was directly antagonistic to the agonists in all three primary cancers contains miR-221 and miR-222. Since both miR-17 ~ 92 and miR-221/222 are considered to be oncogenic this points to a functional antagonism of different oncogenic miRNAs. Analysis of patient data revealed that in certain patients agonistic miRNAs predominated, whereas in other patients antagonists predominated. In glioblastoma a high ratio of miR-17 to miR-221/222 was predictive of better overall survival suggesting that high miR-221/222 expression is more adverse for patients than high miR-17 expression.

CONCLUSION

miRConnect 2.0 is useful for identifying activities of miRNAs that are relevant to primary cancers. The new correlation data on miRNAs and mRNAs deregulated in three primary cancers are available at miRConnect.org.

MicroRNA-99a/100 promotes apoptosis by targeting mTOR in human esophageal squamous cell carcinoma

Recently, microRNA-99 family members, such as miR-99a/b and miR-100, have been reported to exhibit abnormal expression in various malignant tumors, but their functions in carcinomas are controversial. In this study, we focused on miR-99a and miR-100, which were determined to be universally downregulated in esophageal squamous cell carcinoma, and investigated their functions and potential mechanisms of action. The downregulation of miR-99a/100 was validated by qRT-PCR in 101 ESCC surgical tissue samples and in 3 ESCC cell lines. The overexpression of miR-99a and miR-100 via the transient transfection of the corresponding precursor molecules inhibited cell proliferation by inducing apoptosis in the ESCC cell lines. To investigate the molecular mechanism of miR-99a/100-induced apoptosis, luciferase reporter assays and Western blots were performed to demonstrate that the overexpression of miR-99a/100 suppressed the expression of mTOR by directly targeting its 3'UTR in a post-transcriptional manner. Clinically, the decreased expression of miR-99a/100 was associated with worse overall survival in ESCC patients. In conclusion, these results indicated that miR-99a and miR-100 inhibited cell proliferation by suppressing mTOR in ESCC cell lines, and therefore, the miR-99a/100-mTOR signaling pathway is a potential therapeutic target for inducing apoptosis to combat ESCC.

Towards a clinical use of miRNAs in pancreatic cancer biopsies

Pancreatic ductal adenocarcinoma (PDAC) is a devastating disease, despite advances in imaging, surgery and a greater understanding of its molecular biology. Patient outcomes remain poor due to an inability to detect disease early and resistance to anticancer treatments. miRNAs are promised to become ideal cancer biomarkers, as they are tumor and tissue specific and also incredibly stable molecules. So far, large profiling studies of the PDAC miRNome have identified the 'usual suspects' known to be deregulated in solid tumors, such as oncomiR-21, as well as others that could be more robust for differentiating malignant from benign pancreatic disease. However, many of these are yet to be validated clinically. The paper under evaluation provides further evidence for the use of miRNAs as diagnostic biomarkers for PDAC. We have reviewed the use of miRNAs as diagnostic analytes for detecting PDAC in biopsies.