microRNAs with prognostic significance in pancreatic ductal adenocarcinoma: A meta-analysis

Assessing the clinical value of microRNAs in formalin-fixed paraffin-embedded liposarcoma tissues: Overexpressed miR-155 is an indicator of poor prognosis

Liposarcoma (LPS) is a malignancy with extreme heterogeneity and thus optimization towards personalizing patient prognosis and treatment is essential. Here, we evaluated miR-155, miR-21, miR-143, miR-145 and miR-451 that are implicated in LPS, as novel FFPE tissue biomarkers.

A total of 83 FFPE tissue specimens from primary LPS and lipomas (LPM) were analyzed. A proteinase K incubation-Trizol treatment coupled protocol was used for RNA isolation. After polyadenylation of total RNA and reverse transcription, expression analysis of 9 candidate reference and 5 target miRNAs was performed by qPCR. Genorm and NormFinder were used for finding the most suitable molecules for normalization. Survival analyses were performed in order to evaluate the prognostic potential of miRNAs.

MiR-103 and miR-191 are most suitable for normalization of miRNA expression in LPS. MiR-155 and miR-21 are clearly overexpressed (P<0.001) in LPS compared with LPM specimens, whereas miR-145 (P<0.001), miR-143 (P =0.008) and miR-451 (P=0.037) are underexpressed. MiR-155 (P=0.007) and miR-21 (P=0.029) are differentially expressed between well-differentiated, dedifferentiated, myxoid/round cell and pleomorphic LPs tumor subtypes. MiR-155 represents a novel independent indicator of unfavorable prognosis in LPS (HR = 2.97, 95% CI = 1.23–7.17, P = 0.016).

A panel of 13-miRNA signature as a potential biomarker for predicting survival in pancreatic cancer

Some reports have evaluated the prognostic relevance of microRNAs (miRNAs) in patients with pancreatic cancer (PC). However, most studies focused on limited miRNAs with small number of patients. The aim of the study is to identify a panel of miRNA signature that could predict prognosis in PC with the data from The Cancer Genome Atlas (TCGA). A total of 167 PC patients with the corresponding clinical data were enrolled in our study. The miRNAs significantly associated with overall survival (OS) in PC patients were identified with Cox proportional regression model. A risk score formula was developed to evaluate the prognostic value of the miRNA signature in PC. Thirteen miRNAs were identified to be significantly related with OS in PC patients. Patients with high risk score suffered poor overall survival compared with patients who had low risk score. The multivariate Cox regression analyses showed that the miRNA signature could act as an independent prognostic indicator. In addition, the signature might serve as a predicator for treatment outcome. Our study identified a miRNA signature including 13 miRNAs which could serve as an independent marker in prognosis of PC.

An elevated expression of serum exosomal microRNA-191, - 21, -451a of pancreatic neoplasm is considered to be efficient diagnostic marker

BACKGROUND

Pancreatic cancer is associated with an extremely poor prognosis, so new biomarkers that can detect the initial stages are urgently needed. The significance of serum microRNA (miR) levels in pancreatic neoplasm such as pancreatic cancer and intraductal papillary mucinous neoplasm (IPMN) diagnosis remains unclear. We herein evaluated the usefulness of miRs enclosed in serum exosomes (ExmiRs) as diagnostic markers.

METHODS

The ExmiRs from patients with pancreatic cancer (n = 32) or IPMN (n = 29), and patients without neoplasms (controls; n = 22) were enriched using ExoQuick-TC™. The expression of ExmiRs was evaluated using a next-generation sequencing analysis, and the selected three miRs through this analysis were confirmed by a quantitative real-time polymerase chain reaction.

RESULTS

The expression of ExmiR-191, ExmiR-21 and ExmiR-451a was significantly up-regulated in patients with pancreatic cancer and IPMN compared to the controls (p < 0.05). A receiver operating characteristic curve analysis showed that the area under the curve and the diagnostic accuracy of ExmiRs were 5-20% superior to those of three serum bulky circulating miRs (e.g.; ExmiR-21: AUC 0.826, accuracy 80.8%. Circulating miR-21: AUC 0.653, accuracy 62.3%). In addition, high ExmiR-451a was associated with mural nodules in IPMN (p = 0.010), and high ExmiR-21 was identified as a candidate prognostic factor for the overall survival (p = 0.011, HR 4.071, median OS of high-ExmiR-21: 344 days, median OS of low-ExmiR-21: 846 days) and chemo-resistant markers (p = 0.022).

CONCLUSIONS

The level of three ExmiRs can thus serve as early diagnostic and progression markers of pancreatic cancer and IPMN, and considered more useful markers than the circulating miRs (limited to these three miRs).

The role of miRNAs in the diagnosis, chemoresistance, and prognosis of pancreatic ductal adenocarcinoma

Pancreatic ductal adenocarcinoma (PDAC) remains a very challenging malignancy with late presentation, metastatic potential, chemoresistance, and poor prognosis. Therefore, there is an urgent need for novel diagnostic and prognostic biomarkers. miRNAs are small noncoding RNAs that regulate the expression of multitude number of genes. Aberrant expression of miRNAs has been linked to the development of various malignancies, including PDAC. A series of miRNAs have been defined as holding promise for early diagnostics, as indicators of therapy resistance, and even as markers for prognosis in PDAC patients. In this review, we summarize the current knowledge on the role of miRNAs in diagnosis, chemoresistance, and prognosis in PDAC patients.

Noncoding Rnas Emerging as Novel Biomarkers in Pancreatic Cancer

Noncoding RNAs play important regulatory roles in diverse biological processes and their misregulation might lead to different diseases, including cancer. Previous studies have reported the evolving role of miRNAs as new potential biomarkers in cancer diagnosis, prognosis, as well as predictive biomarkers of chemotherapy response or therapeutic targets. In this review, we outline the involvement of noncoding RNA in pancreatic cancer, providing an overview of known miRNAs in its diagnosis, prognosis and chemoresistance. In addition, we discuss the influence of non-coding RNAs in the metastatic behavior of pancreatic cancer, as well as the role of diet in epigenetic regulation of non-coding RNAs in cancer, which can, in turn, lead the development of new prevention's techniques or novel targets for cancer therapy.

Prognostic microRNAs and their potential molecular mechanism in pancreatic cancer: A study based on The Cancer Genome Atlas and bioinformatics investigation

Although certain biomarkers that are directly associated with the overall survival (OS) of patients with pancreatic adenocarcinoma (PAAD) have been identified, the efficacy of a single factor is limited to predicting the prognosis. The aim of the present study was to identify a combination micro (mi)RNA signature that enhanced the prognostic prediction for PAAD. Following analysis of the data available from The Cancer Genome Atlas (TCGA), 175 PAAD samples were selected for the present study, and the associations between 494 miRNAs and OS were investigated. The prognostic value of all miRNAs was analyzed by multivariate Cox regression, and the miRNAs were ranked according to the hazard ratio (HR) and P-values. The top 5 miRNAs (miR-1301, miR-125a, miR-376c, miR-328 and miR-376b) were significantly associated with OS (HR=0.139; 95% confidence interval, 0.043–0.443; P<0.001), thus demonstrating that this panel was able to serve as an independent prognostic factor for PAAD. In addition, the present study also predicted the target genes of the top 10 miRNAs with the highest prognostic values using 12 different prediction software, and enrichment signaling pathway analyses elucidated that several pathways may be markedly associated with these miRNAs, including ‘Pathways in cancer’, ‘Chronic myeloid leukemia’, ‘Glioma’ and ‘MicroRNAs in cancer’. Lastly, ubiquitin C, epidermal growth factor receptor, estrogen receptor 1, mitogen-activated protein kinase 1, mothers against decapentaplegic homolog 4 and androgen receptor may be the hub genes revealed by STRING analysis. The present study identified several miRNAs, particularly a five-miRNA-pool, that may be reliable, independent factors for predicting survival in patients with PAAD. However, the underlying molecular mechanisms require further investigation in the future.

Plasma exosome miR-196a and miR-1246 are potential indicators of localized pancreatic cancer

Patients with localized pancreatic cancer (stage I and stage IIA) have a much higher survival rate than those presenting at later stages, yet early detection remains a challenge to this malignancy. The aim of this study was to evaluate whether exosome miRNA signatures are indicative of localized pancreatic cancer. Exosomes were collected from the conditioned media of pancreatic cancer cell lines and plasma samples of localized pancreatic cancer patients (Stage I-IIA, n=15), and healthy subjects (n=15). Cellular and exosome miRNAs from pancreatic cancer cell lines were profiled by next-generation small RNA sequencing. Plasma exosome miRNA expression was analyzed by qRT-PCR. We found that certain miRNAs, such as miR-196a and miR-1246, are highly enriched in pancreatic cancer exosomes. Consistently, plasma exosome miR-196a and miR-1246 levels were significantly elevated in pancreatic cancer patients as compared to healthy subjects. An analysis of the cancer subtypes indicated that plasma exosome miR-196a is a better indicator of pancreatic ductal adenocarcinoma (PDAC), whereas plasma exosome miR-1246 is significantly elevated in patients with intraductal papillary mucinous neoplasms (IPMN). In contrast, there were no differences in the plasma exosome miR-196a and miR-1246 levels between patients with pancreatic neuroendocrine tumors (NET) and healthy subjects. In conclusion, we demonstrate that certain miRNA species, such as miR-196a and miR-1246, are highly enriched in pancreatic cancer exosomes and elevated in plasma exosomes of patients with localized pancreatic cancer.

Prognostic value of microRNA expression levels in pancreatic adenocarcinoma: a review of the literature

Background

Clinical and pathologic markers of prognosis and patterns of failure help guide clinicians in selecting patients for adjuvant therapy after surgical resection for pancreatic adenocarcinoma (PDAC). Recent studies have reported the prognostic utility of microRNA profiling in numerous malignancies. Here, we review and summarize the current literature regarding associations between microRNA expression and overall survival in PDAC patients.

Materials and Methods

We conducted a systematic search in the PubMed database to identify all primary research studies reporting prognostic associations between tumor and/or serum microRNA expression and overall survival in PDAC patients. Eligible articles were reviewed by the authors and relevant findings are summarized below.

Results

We found 53 publications that fit our search criteria. In total, 23 up-regulated and 49 down-regulated miRNAs have been associated with worse overall survival. MiR-21 is the most commonly reported miRNA, appearing in 19 publications, all of which report aberrant over-expression and association with shorter survival in PDAC. Other miRNAs that appear in multiple publications include miR-10b, −21, −34a, −155, −196a, −198, −200c, −203, −210, −218, −222, and −328. We summarize the preclinical and clinical data implicating these miRNAs in various molecular signaling pathways and cellular functions.

Conclusions

There is growing evidence that miRNA expression profiles have the potential to provide tumor-specific prognostic information to assist clinicians in more appropriately selecting patients for adjuvant therapy. These molecules are often aberrantly expressed and exhibit oncogenic and/or tumor suppressor functions in PDAC. Additional efforts to develop prognostic and predictive molecular signatures, and further elucidate miRNA mechanisms of action, are warranted.

Integrated Genomic Characterization of Pancreatic Ductal Adenocarcinoma

We performed integrated genomic, transcriptomic, and proteomic profiling of 150 pancreatic ductal adenocarcinoma (PDAC) specimens, including samples with characteristic low neoplastic cellularity. Deep whole-exome sequencing revealed recurrent somatic mutations in KRAS, TP53, CDKN2A, SMAD4, RNF43, ARID1A, TGFβR2, GNAS, RREB1, and PBRM1. KRAS wild-type tumors harbored alterations in other oncogenic drivers, including GNAS, BRAF, CTNNB1, and additional RAS pathway genes. A subset of tumors harbored multiple KRAS mutations, with some showing evidence of biallelic mutations. Protein profiling identified a favorable prognosis subset with low epithelial-mesenchymal transition and high MTOR pathway scores. Associations of non-coding RNAs with tumor-specific mRNA subtypes were also identified. Our integrated multi-platform analysis reveals a complex molecular landscape of PDAC and provides a roadmap for precision medicine.

MicroRNAs with prognostic significance in bladder cancer: a systematic review and meta-analysis

The aim of this study was to systematically review articles that investigated the prognostic significance of different microRNAs in bladder cancer (BC). We systematically searched PubMed, Web of Science, and Embase to identify relevant studies until March 2016. After screening, 26 studies that involved 2753 patients were included. Results suggested that many miRs expression aberration may predict prognosis in patients with BC. There are six miRs (miR-21, miR-143, miR-155, miR-200, miR-214, and miR-222) were reported by at least two studies, and we performed meta-analysis in the corresponding studies. Accordingly, we found that high miR-21 expression was associated with poor overall survival [OS; hazard ratio (HR) = 3.94, 95% CI 2.08–7.44]. High miR-143 expression was associated with poor progression-free survival (PFS; HR = 3.78, 95% CI 1.61–8.89). High miR-155 expression was associated with poor PFS (HR = 8.10, 95% CI 2.92–22.48). High miR-222 expression was associated with poor OS (HR = 3.39, 95% CI 1.10–10.41). Meanwhile, low miR-214 expression was correlated with poor RFS(HR = 0.34, 95% CI 0.22–0.53). Our comprehensive systematic review concluded that microRNAs, particularly miR-21, miR-143, miR-155, miR-214, and miR-222, could serve as meticulous follow-up markers for early detection of progression or recurrence and even useful therapeutic targets for the treatment in patients with BC.

Murine and human pancreatic tumor exosome recovery in mouse serum: Diagnostic and prognostic potential and target cell delivery

Exosomes (Exo), powerful intercellular communicators, are recovered in all body fluids, suggesting suitability for diagnosis and prognosis. Easy in vitro manipulation recommends Exo as drug vehicles. Aiming to consolidate diagnostic and therapeutic potential of Exo, we evaluated recovery and fate of tumor (TEX) and exogenous Exo in syngeneic and xenogeneic mice bearing a murine or a human pancreatic adenocarcinoma. A significant increase in serum (S)-TEX was observed 2 weeks after tumor cell application. Instead, S-TEX declined within 3-6 days after tumor excision. Intravenously injected dye-labeled TEX were rapidly cleared from the serum. Partly being degraded in the liver, the majority is taken-up by PBL, liver, bone marrow and lung cells. In the tumor-bearing host TEX persisted longer becoming enriched in tumor cells and metastatic organs. Accordingly, an antibody blockade of a TEX marker hampered disseminated tumor cell settlement in selected organs. In brief, a tumor marker panel appears suited for S-TEX recovery. In murine models, S-TEX are qualified for therapy control and follow-up studies. Despite rapid clearance from the serum, Exo uptake by host cells is most promising for tailored Exo as drug transporter.

Key biological processes driving metastatic spread of pancreatic cancer as identified by multi-omics studies

Pancreatic ductal adenocarcinoma (PDAC) is an extremely aggressive malignancy, characterized by a high metastatic burden, already at the time of diagnosis. The metastatic potential of PDAC is one of the main reasons for the poor outcome next to lack of significant improvement in effective treatments in the last decade. Key mutated driver genes, such as activating KRAS mutations, are concordantly expressed in primary and metastatic tumors. However, the biology behind the metastatic potential of PDAC is not fully understood. Recently, large-scale omic approaches have revealed new mechanisms by which PDAC cells gain their metastatic potency. In particular, genomic studies have shown that multiple heterogeneous subclones reside in the primary tumor with different metastatic potential. The development of metastases may be correlated to a more mesenchymal transcriptomic subtype. However, for cancer cells to survive in a distant organ, metastatic sites need to be modulated into pre-metastatic niches. Proteomic studies identified the influence of exosomes on the Kuppfer cells in the liver, which could function to prepare this tissue for metastatic colonization. Phosphoproteomics adds an extra layer to the established omic techniques by unravelling key functional signaling. Future studies integrating results from these large-scale omic approaches will hopefully improve PDAC prognosis through identification of new therapeutic targets and patient selection tools. In this article, we will review the current knowledge on the biology of PDAC metastasis unravelled by large scale multi-omic approaches.

MicroRNAs in the prognosis of triple-negative breast cancer: A systematic review and meta-analysis

BACKGROUND

Triple-negative breast cancer (TNBC) is a heterogeneous group of tumors characterized by their aggressive nature and poor associated survival. MicroRNAs (miRs) have been found to play an important role in the occurrence and development of human cancers, but their role in the prognosis of TNBC patients remains unclear. We performed a meta-analysis to explore the prognostic value of miRs in TNBC.

METHODS

We systematically searched the PubMed, Embase, and Web of Science databases to identify eligible studies. A meta-analysis was performed to estimate the pooled hazard ratios (HRs) and their corresponding 95% confidence intervals (CIs) for the associations between levels of miR expression (predictive factors) and overall survival (OS) and disease-free survival (DFS) (outcomes) in patients with TNBC.

RESULTS

After performing the literature search and review, 21 relevant studies including 2510 subjects were identified. Six miRs (miR-155, miR-21, miR-27a/b, miR-374a/b, miR-210, and miR-454) were assessed in the meta-analysis. Decreased expression of miR-155 was associated with reduced OS (adjusted HR = 0.58, 95% CI: 0.34-0.99; crude HR = 0.67, 95% CI: 0.58-0.79). High miR-21 expression was also predictive of reduced OS (crude HR = 2.50, 95% CI: 1.56-4.01). We found that elevated levels of miR-27a/b, miR-210, and miR-454 expression were associated with shorter OS, while the levels of miR-454 and miR-374a/b expression were associated with DFS.

CONCLUSIONS

Specific miRs could serve as potential prognostic biomarkers in TNBC. Due to the limited research available, the clinical application of these findings has yet to be verified.

Serological characteristics of autoimmune pancreatitis and its differential diagnosis from pancreatic cancer by using a combination of carbohydrate antigen 19-9, globulin, eosinophils and hemoglobin

Autoimmune pancreatitis (AIP) is a special type of chronic pancreatitis, which may be misdiagnosed as pancreatic carcinoma. This study aims to verify new biomarkers for AIP and propose a serological pattern to differentiate AIP from pancreatic adenocarcinoma with routinely performed tests. In this study, data of serum samples were collected and compared between 25 patients with AIP and 100 patients with pancreatic carcinoma. Receiver operating characteristic analysis and logistic regression was performed to evaluate the diagnostic effect of serum parameters in differentiating AIP from pancreatic carcinoma alone or in combination. Among several serum markers observed in the two groups, carbohydrate antigen 19-9 (Ca19-9), globulin, eosinophils and hemoglobin were selected as the independent markers. Serum levels of Globulin, Eosinophil percentage in AIP group were significantly higher than in pancreatic cancer group (P<0.05), while hemoglobin and tumor marker CA19-9 levels were lower (P <0.05). The combination of these markers identified patients with AIP with 92% sensitivity and 79% specificity, which indicated relatively high diagnostic value. Elevated serum eosinophils, globulin, together with decreased hemoglobin level can be used as a preoperative indicator for AIP and can help to initiate diagnosis of AIP in time.

Molecular alterations contributing to pancreatic cancer chemoresistance

Pancreatic ductal adenocarcinoma (PDAC) is one of the most common causes of cancer-related death all over the world. This disease is difficult to treat and patients have an overall 5-year survival rate of less than 5%. Although two drugs, gemcitabine (GEM) and 5-fluorouracil (5-FU) have been shown to improve the survival rate of patients systematically, they do not increase general survival to a clinically acceptable degree. Lack of ideal clinical response of pancreatic cancer patients to chemotherapy is likely to be due to intrinsic and acquired chemoresistance of tumor cells. Various mechanisms of drug resistance have been investigated in pancreatic cancer, including genetic and epigenetic changes in particular genes or signaling pathways. In addition, evidence suggests that microRNAs (miRNAs) play significant roles as key regulators of gene expression in many cellular processes, including drug resistance. Understanding underlying genes and mechanisms of drug resistance in pancreatic cancer is critical to develop new effective treatments for this deadly disease. This review illustrates the genes and miRNAs involved in resistance to gemcitabine in pancreatic cancer.

The underlying mechanisms of non-coding RNAs in the chemoresistance of pancreatic cancer

Pancreatic cancer, which is often asymptomatic, is currently one of the most common causes of cancer-related death. This phenomenon is most likely due to a lack of early diagnosis, a high metastasis rate and a disappointing chemotherapy outcome. Thus, improving treatment outcomes by overcoming chemotherapy resistance may be a useful strategy in pancreatic cancer. Various underlying mechanisms involved in the chemoresistance of pancreatic cancer have been investigated. Notably, non-coding RNAs (ncRNAs), especially microRNAs (miRNAs) and long non-coding RNAs (lncRNAs), play a pivotal role in regulating sensitivity to chemotherapy in pancreatic cancer. In this review, we highlight recent evidence regarding the role of miRNAs and lncRNAs in the chemoresistance of pancreatic cancer, including their expression levels, targets, biological functions and the regulation of chemoresistance, and discuss the potential clinical application of miRNAs and lncRNAs in the treatment of pancreatic cancer.

MicroRNA-155 Controls Exosome Synthesis and Promotes Gemcitabine Resistance in Pancreatic Ductal Adenocarcinoma

The cancer drug gemcitabine (GEM) is a key drug for treating pancreatic ductal adenocarcinoma (PDAC), but PDAC cells develop chemoresistance after long-term administration. Since the tolerance was immediately spread to every PDAC tissue in a patient, it is assumed that some certain efficient mechanisms underlay in the development of chemoresistance. Changes in the levels of particular microRNAs or alterations in intercellular communication play a dominant role in chemoresistance development, and recent data also suggest that exosomes play an important role in this process. In this study, we revealed that the loop conferred chemoresistance in PDAC cells. The loop was as follows; 1, The long-term exposure of GEM increased miR-155 expression in PDAC cells. 2, The increase of miR-155 induced two different functions; exosome secretion and chemoresistance ability via facilitating the anti-apoptotic activity. 3, Exosome deliver the miR-155 into the other PDAC cells and induce the following function. The target therapy to miR-155 or the exosome secretion effectively attenuated the chemoresistance, and these results were validated with both clinical samples and in vivo experiments. This mechanism represents a novel therapeutic target in GEM treatment to PDAC.

Pseudogene PTENP1 Functions as a Competing Endogenous RNA (ceRNA) to Regulate PTEN Expression by Sponging miR-499-5p

Increasing evidence has shown that pseudogenes can widely regulate gene expression. However, little is known about the specific role of PTENP1 and miR-499-5p in insulin resistance. The relative transcription level of PTENP1 was examined in db/db mice and high fat diet (HFD)-fed mice by real-time PCR. To explore the effect of PTENP1 on insulin resistance, adenovirus overexpressing or inhibiting vectors were injected through the tail vein. Bioinformatics predictions and a luciferase reporter assay were used to explore the interaction between PTENP1 and miR-499-5p. The relative transcription level of PTENP1 was largely enhanced in db/db mice and HFD-fed mice. Furthermore, the overexpression of PTENP1 resulted in impaired Akt/GSK activation as well as glycogen synthesis, while PTENP1 inhibition led to the improved activation of Akt/GSK and enhanced glycogen contents. More importantly, PTENP1 could directly bind miR-499-5p, thereby becoming a sink for miR-499-5p. PTENP1 overexpression results in the impairment of the insulin-signaling pathway and may function as a competing endogenous RNA for miR-499-5p, thereby contributing to insulin resistance.

Noncoding RNAs as novel biomarkers in pancreatic cancer: what do we know?

Pancreatic cancer is an aggressive cancer of the digestive system, which is becoming a serious health problem worldwide. Overall survival for patients with pancreatic cancer is poor, mainly due to a lack of biomarkers to enable early diagnosis and a lack of prognostic markers that can inform decision-making, facilitating personalized treatment and an optimal clinical outcome. ncRNAs play an important role in pancreatic carcinogenesis. Here we review the literature on the role of ncRNAs as biomarkers in pancreatic cancer. We focus on the significance of ncRNAs as markers for early diagnosis, as prognostic biomarkers able to inform clinical management and as targets for novel therapeutics for patients with pancreatic cancer.

Downregulated miR-506 expression facilitates pancreatic cancer progression and chemoresistance via SPHK1/Akt/NF-κB signaling

The aberrant expression of microRNAs (miRNAs) has emerged as an important hallmark of cancer. However, the molecular mechanisms underlying the changes in miRNA expression remain unclear. In this study, we discovered a novel epigenetic mechanism of miR-506 regulation and investigated its functional significance in pancreatic cancer. Sequencing analysis revealed that the miR-506 promoter is highly methylated in pancreatic cancer tissues compared with non-cancerous tissues. Reduced miR-506 expression was significantly associated with clinical stage, pathologic tumor status, distant metastasis and decreased survival of pancreatic cancer patients. miR-506 inhibited cell proliferation, induced cell cycle arrest at the G1/S transition and enhanced apoptosis and chemosensitivity of pancreatic cancer cells. Furthermore, we identified sphingosine kinase 1 (SPHK1) as a novel target of miR-506, the expression of which inhibited the SPHK1/Akt/NF-κB signaling pathway, which is activated in pancreatic cancer. High SPHK1 expression was significantly associated with poor survival in a large cohort of pancreatic cancer specimens. Our data suggest that miR-506 acts as a tumor suppressor miRNA and is epigenetically silenced in pancreatic cancer. The newly identified miR-506/SPHK1 axis represents a novel therapeutic strategy for future pancreatic cancer treatment.

Cancer Salivary Biomarkers for Tumours Distant to the Oral Cavity

The analysis of saliva as a diagnostic approach for systemic diseases was proposed just two decades ago, but recently great interest in the field has emerged because of its revolutionary potential as a liquid biopsy and its usefulness as a non-invasive sampling method. Multiple molecules isolated in saliva have been proposed as cancer biomarkers for diagnosis, prognosis, drug monitoring and pharmacogenetic studies. In this review, we focus on the current status of the salivary diagnostic biomarkers for different cancers distant to the oral cavity, noting their potential use in the clinic and their applicability in personalising cancer therapies.

The Clinical Significance of miR-34a in Pancreatic Ductal Carcinoma and Associated Molecular and Cellular Mechanisms

BACKGROUND

Pancreatic ductal adenocarcinoma (PDAC) exhibits poor prognosis and resistance to chemotherapy. This study was to identify the biomarkers associated with the progression, poor prognosis and chemoresistance of PDAC.

METHODS

miR-34a and miR-150 levels in the plasma and tissues from PDAC patients were measured by real-time PCR. Xenograft PDAC tumor models were established in mice by inoculation of CD133+ stem cells isolated from PDAC tumors. Protein expression was measured by Western blot.

RESULTS

The plasma miR-34a and miR-150 levels were significantly lower in PDAC patients than in patients with benign pancreatic lesions and in healthy subjects. The miR-34a and miR-150 levels in the tumor tissues were significantly lower than in pancreatic tissues with benign lesions. The protein levels of CD133, Notch1, Notch2 and Notch4 receptors in PDAC tumor tissues were significantly higher than in pancreatic tissues with benign lesions. miR-34a injection significantly inhibited the tumor growth of PDAC tumors and sensitized the anticancer effects of 5-fluorouracil (5-FU). miR-34a significantly inhibited Notch1, Notch2 and Notch4 expression in xenograft tumor tissues in vivo and BxPC-3 cells in vitro. miR-34a and miR-150 significantly induced apoptosis and inhibited proliferation, invasion and migration in BxPC-3 cells. miR-34a, but not miR-150, significantly sensitized the anticancer effect of 5-FU in BxPC-3 cells in vitro.

CONCLUSION

A loss of expression of miR-34a, but not of miR-150, is associated with disease progression and poor prognosis in PDAC patients, and may be involved in the chemoresistance of PDAC cells.

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.

Surgical and molecular pathology of pancreatic neoplasms

BACKGROUND

Histologic characteristics have proven to be very useful for classifying different types of tumors of the pancreas. As a result, the major tumor types in the pancreas have long been classified based on their microscopic appearance.

MAIN BODY

Recent advances in whole exome sequencing, gene expression profiling, and knowledge of tumorigenic pathways have deepened our understanding of the underlying biology of pancreatic neoplasia. These advances have not only confirmed the traditional histologic classification system, but also opened new doors to early diagnosis and targeted treatment.

CONCLUSION

This review discusses the histopathology, genetic and epigenetic alterations and potential treatment targets of the five major malignant pancreatic tumors - pancreatic ductal adenocarcinoma, pancreatic neuroendocrine tumor, solid-pseudopapillary neoplasm, acinar cell carcinoma and pancreatoblastoma.

Progress and potential of exosome analysis for early pancreatic cancer detection

INTRODUCTION

Pancreatic cancer (PaCa) is the most deadly malignancy, due to late diagnosis prohibiting surgery. Thus, strong efforts are taken improving early diagnosis via biomarkers recovered in the serum of PaCa patients.

AREAS COVERED

One promising option are PaCa-derived exosomes in patients' sera. Exosomes, small vesicles delivered by live cells and recovered in all body fluids, are a powerful diagnostic tool due to relative stability and composition covering the whole range of cancer-related biomarkers including proteins, metabolites, DNA, DNA modifications, coding and noncoding RNA. We discuss the mechanisms accounting for the condensed packaging of biomarkers, refer to studies using PaCa serum-exosomes for diagnosis. Based on an extensive literature search, we outline questions that answers may help establishing a serum-exosome-based screening for early PaCa detection. Expert commentary: Improved proteomic and genomic characterization and progress in the biogenesis of exosomes will allow for optimized and unified screening panels for PaCa diagnosis via TEX in body fluids.

Serum microRNA-196 and microRNA-200 in pancreatic ductal adenocarcinoma of patients with diabetes mellitus

BACKGROUND/OBJECTIVES

Our aim was to compare expressions of 6 microRNAs (miRNAs) in patients with pancreatic ductal adenocarcinoma (PAC) and non-cancer patients, moreover according to the presence or absence of diabetes mellitus.

METHODS

Expressions of miRNA-192, -196, -200, -21, -30 and -423 were measured in 77 patients with PAC and 64 non-cancer patients (34 patients with type 2 DM and 30 control persons). 60 patients with PAC (78%) had DM or prediabetes and it was of new-onset (less than 2 years before the cancer diagnosis) in 44 out of them.

RESULTS

The expressions of all microRNAs were 1.4-3.7 times higher (significantly) in the PAC group compared to non-cancer patients. No difference was found between PAC diabetic and PAC non-diabetic patients. MicroRNA-200 was significantly higher in PAC patients with significant body weight loss against those without weight loss. Adding miRNA-196 and -200 to the current marker CA 19-9 improved the discriminative ability of the test (compared to CA 19-9 alone).

CONCLUSION

MicroRNA-196 and -200 could be used as additional markers in PAC diagnosis.

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.

Identification of key regulators of pancreatic cancer progression through multidimensional systems-level analysis

BACKGROUND

Pancreatic cancer is an aggressive cancer with dismal prognosis, urgently necessitating better biomarkers to improve therapeutic options and early diagnosis. Traditional approaches of biomarker detection that consider only one aspect of the biological continuum like gene expression alone are limited in their scope and lack robustness in identifying the key regulators of the disease. We have adopted a multidimensional approach involving the cross-talk between the omics spaces to identify key regulators of disease progression.

METHODS

Multidimensional domain-specific disease signatures were obtained using rank-based meta-analysis of individual omics profiles (mRNA, miRNA, DNA methylation) related to pancreatic ductal adenocarcinoma (PDAC). These domain-specific PDAC signatures were integrated to identify genes that were affected across multiple dimensions of omics space in PDAC (genes under multiple regulatory controls, GMCs). To further pin down the regulators of PDAC pathophysiology, a systems-level network was generated from knowledge-based interaction information applied to the above identified GMCs. Key regulators were identified from the GMC network based on network statistics and their functional importance was validated using gene set enrichment analysis and survival analysis.

RESULTS

Rank-based meta-analysis identified 5391 genes, 109 miRNAs and 2081 methylation-sites significantly differentially expressed in PDAC (false discovery rate ≤ 0.05). Bimodal integration of meta-analysis signatures revealed 1150 and 715 genes regulated by miRNAs and methylation, respectively. Further analysis identified 189 altered genes that are commonly regulated by miRNA and methylation, hence considered GMCs. Systems-level analysis of the scale-free GMCs network identified eight potential key regulator hubs, namely E2F3, HMGA2, RASA1, IRS1, NUAK1, ACTN1, SKI and DLL1, associated with important pathways driving cancer progression. Survival analysis on individual key regulators revealed that higher expression of IRS1 and DLL1 and lower expression of HMGA2, ACTN1 and SKI were associated with better survival probabilities.

CONCLUSIONS

It is evident from the results that our hierarchical systems-level multidimensional analysis approach has been successful in isolating the converging regulatory modules and associated key regulatory molecules that are potential biomarkers for pancreatic cancer progression.

The role of exosomes in the pathogenesis of pancreatic ductal adenocarcinoma

Exosomes are small membrane bound vesicles secreted by cancer cells that have a cytosol rich in proteins and nucleic acids which are capable of modulating the phenotype of neighbouring cells which take them up. In this review we explore the mechanisms through which exosomes are able to impact on the pathogenesis of pancreatic ductal cancer through the modulation of tumour formation and development and exploitation of the tumour microenvironment to modulate both the adaptive and innate immune response. In addition we highlight the potential utility of exosomes not only as biomarkers of disease but also as tools to be used in the therapeutic armamentarium against this disease.

miR-21 expression and clinical outcome in locally advanced pancreatic cancer: exploratory analysis of the pancreatic cancer Erbitux, radiotherapy and UFT (PERU) trial

BACKGROUND

Locally advanced pancreatic cancer (LAPC) is associated with high mortality, and biomarker-driven treatment approach is currently lacking. This study evaluated safety and efficacy of a combination approach of chemotherapy followed by chemo-radiotherapy (CRT) +/- cetuximab, and the prognostic role of miR-21 in patients with LAPC treated with a multimodality approach.

PATIENTS AND METHODS

This was a randomised phase II trial in which patients with inoperable LAPC were offered gemcitabine and capecitabine (GEM-CAP) for 16 weeks. Patients with stable disease or response after GEM-CAP were randomised to capecitabine or UFT plus radiotherapy (RT) (A), or capecitabine or UFT plus cetuximab plus RT (B). The primary outcome of the study was overall survival (OS). Clinical outcome was compared according to baseline circulating miR-21 levels.

RESULTS

17 patients were enrolled and treated with GEM-CAP, with 13 patients achieving disease control and being randomised to arms A (n:7) and B (n:6). After a median follow-up of 61.2 months, median progression free survival (PFS) was 10.4 months and 12.7 months, median OS was 15.8 months and 22.0 months in arms A and B respectively (p > 0.05). Patients with high baseline plasma miR-21 had worse PFS (3.5 vs. 12.7 months; p:0.032) and OS (5.1 vs 15.3 months; p:0.5) compared to patients with low miR-21. Circulating miR-21 levels reflected miR-21 expression within the tissues.

CONCLUSIONS

Addition of Cetuximab to CRT following induction chemotherapy did not improve survival. High miR-21 baseline plasma expression was associated with poor clinical outcome in LAPC patients treated with induction chemotherapy followed by chemo-radiotherapy.

Circulating microRNAs as diagnostic biomarkers for pancreatic cancer

There is an urgent need for novel and reliable biomarkers for the diagnosis and prognostication of pancreatic ductal adenocarcinoma (PDAC). Circulating microRNAs (miRNAs) have been extensively profiled in PDAC blood samples, but few studies have performed adequate validation of candidate markers. The evaluated study by Xu et al. investigated pre-operative plasma miRNAs from PDAC patients over three phases and three surgical centers. They revealed miR-486-5p and miR-938 were able to discriminate PDAC patients from healthy controls and those with chronic pancreatitis. The diagnostic ability of miR-486-5p for identifying PDAC from healthy controls was comparable to that of CA 19-9. This study provides further evidence for the use of blood-based miRNAs as diagnostic biomarkers in PDAC. However, as these have not been identified in previous studies these require further validation and methodology needs to be standardized if these are ever to be used in the clinic.

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.

Anti-inflammatory effects of miR-21 in the macrophage response to peritonitis

We investigated the role of microRNA-21 in the macrophage response to peritonitis; microRNA-21 expression increases in peritoneal macrophages after lipopolysaccharide stimulation but is delayed until 48 hours after cecal ligation and puncture. MicroRNA-21-null mice and bone marrow-derived cell lines were exposed to cecal ligation and puncture or lipopolysaccharide, and survival, microRNA-21 levels, target messenger RNAs and proteins, and cytokines were assayed. Macrophages were also transfected with microRNA-21 mimics and antagomirs, and similar endpoints were measured. Survival in microRNA-21-null mice was significantly decreased after lipopolysaccharide-induced peritonitis but unchanged after cecal ligation and puncture compared with similarly treated wild-type mice. MicroRNA-21 expression, tumor necrosis factor-α, interleukin 6, and programmed cell death protein 4 levels were increased after lipopolysaccharide addition in peritoneal cells. Pelino1 and sprouty (SPRY) messenger RNAs were similarly increased early, whereas programmed cell death protein 4 messenger RNA was decreased after lipopolysaccharide, and all microR-21 target messenger RNAs were subsequently decreased by 24 hours after lipopolysaccharide. Transfection with mimics and antagomirs led to appropriate responses in microRNA-21 and tumor necrosis factor-α. Knockdown of microRNA-21 in bone marrow-derived cells showed increased tumor necrosis factor-α and decreased interleukin 10 in response to lipopolysaccharide. Target proteins were unaffected by knockdown as was extracellular signal-regulated kinase; however, the nuclear factor κB p65 subunit was increased after lipopolysaccharide in the microRNA-21 knockout cells. In contrast, there was little change in these parameters after cecal ligation and puncture induction between null and wild-type mice. MicroRNA-21 is beneficial to survival in mice following lipopolysaccharide peritonitis. Overexpression of microRNA-21 decreased tumor necrosis factor-α secretion, whereas suppression of microRNA-21 expression increased tumor necrosis factor-α and interleukin 6, and decreased interleukin 10 levels after lipopolysaccharide. Protein targets of microRNA-21 were not different following suppression of microRNA-21. Nuclear factor κB was increased by suppression of microRNA-21. These findings demonstrate microRNA-21 is beneficial in modulating the macrophage response to lipopolysaccharide peritonitis and an improved understanding of the anti-inflammatory effects of microRNA-21 may result in novel, targeted therapy against peritonitis and sepsis.