MicroRNA-34b inhibits pancreatic cancer metastasis through repressing Smad3

Using microRNAs Networks to Understand Pancreatic Cancer-A Literature Review

Pancreatic cancer is a severe disease, challenging to diagnose and treat, and thereby characterized by a poor prognosis and a high mortality rate. Pancreatic ductal adenocarcinoma (PDAC) represents approximately 90% of pancreatic cancer cases, while other cases include neuroendocrine carcinoma. Despite the growing knowledge of the pathophysiology of this cancer, the mortality rate caused by it has not been effectively reduced. Recently, microRNAs have aroused great interest among scientists and clinicians, as they are negative regulators of gene expression, which participate in many processes, including those related to the development of pancreatic cancer. The aim of this review is to show how microRNAs (miRNAs) affect key signaling pathways and related cellular processes in pancreatic cancer development, progression, diagnosis and treatment. We included the results of in vitro studies, animal model of pancreatic cancer and those performed on blood, saliva and tumor tissue isolated from patients suffering from PDAC. Our investigation identified numerous dysregulated miRNAs involved in KRAS, JAK/STAT, PI3/AKT, Wnt/β-catenin and TGF-β signaling pathways participating in cell cycle control, proliferation, differentiation, apoptosis and metastasis. Moreover, some miRNAs (miRNA-23a, miRNA-24, miRNA-29c, miRNA-216a) seem to be engaged in a crosstalk between signaling pathways. Evidence concerning the utility of microRNAs in the diagnosis and therapy of this cancer is poor. Therefore, despite growing knowledge of the involvement of miRNAs in several processes associated with pancreatic cancer, we are beginning to recognize and understand their role and usefulness in clinical practice.

Illuminating the pathogenic role of SARS-CoV-2: Insights into competing endogenous RNAs (ceRNAs) regulatory networks

The appearance of SARS-CoV-2 in 2019 triggered a significant economic and health crisis worldwide, with heterogeneous molecular mechanisms that contribute to its development are not yet fully understood. Although substantial progress has been made in elucidating the mechanisms behind SARS-CoV-2 infection and therapy, it continues to rank among the top three global causes of mortality due to infectious illnesses. Non-coding RNAs (ncRNAs), being integral components across nearly all biological processes, demonstrate effective importance in viral pathogenesis. Regarding viral infections, ncRNAs have demonstrated their ability to modulate host reactions, viral replication, and host-pathogen interactions. However, the complex interactions of different types of ncRNAs in the progression of COVID-19 remains understudied. In recent years, a novel mechanism of post-transcriptional gene regulation known as "competing endogenous RNA (ceRNA)" has been proposed. Long non-coding RNAs (lncRNAs), circular RNAs (circRNAs), and viral ncRNAs function as ceRNAs, influencing the expression of associated genes by sequestering shared microRNAs. Recent research on SARS-CoV-2 has revealed that disruptions in specific ceRNA regulatory networks (ceRNETs) contribute to the abnormal expression of key infection-related genes and the establishment of distinctive infection characteristics. These findings present new opportunities to delve deeper into the underlying mechanisms of SARS-CoV-2 pathogenesis, offering potential biomarkers and therapeutic targets. This progress paves the way for a more comprehensive understanding of ceRNETs, shedding light on the intricate mechanisms involved. Further exploration of these mechanisms holds promise for enhancing our ability to prevent viral infections and develop effective antiviral treatments.

Functional and Potential Therapeutic Implication of MicroRNAs in Pancreatic Cancer

The alarmingly low five-year survival rate for pancreatic cancer presents a global health challenge, contributing to about 7% of all cancer-related deaths. Late-stage diagnosis and high heterogeneity are the biggest hurdles in treating pancreatic cancer. Thus, there is a pressing need to discover novel biomarkers that could help in early detection as well as improve therapeutic strategies. MicroRNAs (miRNAs), a class of short non-coding RNA, have emerged as promising candidates with regard to both diagnostics and therapeutics. Dysregulated miRNAs play pivotal roles in accelerating tumor growth and metastasis, orchestrating tumor microenvironment, and conferring chemoresistance in pancreatic cancer. The differential expression profiles of miRNAs in pancreatic cancer could be utilized to explore novel therapeutic strategies. In this review, we also covered studies on recent advancements in various miRNA-based therapeutics such as restoring miRNAs with a tumor-suppressive function, suppressing miRNA with an oncogenic function, and combination with chemotherapeutic drugs. Despite several challenges in terms of specificity and targeted delivery, miRNA-based therapies hold the potential to revolutionize the treatment of pancreatic cancer by simultaneously targeting multiple signaling pathways.

Investigating the regulatory role of miRNAs as silent conductors in the management of pathogenesis and therapeutic resistance of pancreatic cancer

Pancreatic cancer (PC) has the greatest mortality rate of all the main malignancies. Its advanced stage and poor prognosis place it at the bottom of all cancer sites. Hence, emerging biomarkers can enable precision medicine where PC therapy is tailored to each patient. This highlights the need for new, highly sensitive and specific biomarkers for early PC diagnosis. Prognostic indicators are also required to stratify PC patients. To avoid ineffective treatment, adverse events, and expenses, biomarkers are also required for patient monitoring and identifying responders to treatment. There is substantial evidence that microRNAs (miRs, miRNAs) play a critical role in regulating mRNA and, as a consequence, protein expression in normal and malignant tissues. Deregulated miRNA profiling in PC can help with diagnosis, treatment planning, and prognosis. Furthermore, knowledge of the primary effector genes and downstream pathways in PC can help pinpoint potential miRNAs for use in treatment. Different miRNA expression profiles may serve as diagnostic, prognostic markers, and therapeutic targets across the spectrum of malignant pancreatic illness. Dysregulation of miRNAs has been linked to the malignant pathophysiology of PC through affecting many cellular functions such as increasing invasive and proliferative prospect, supporting angiogenesis, cell cycle aberrance, apoptosis elusion, metastasis promotion, and low sensitivity to particular treatments. Accordingly, in the current review, we summarize the recent advances in the roles of oncogenic and tumor suppressor (TS) miRNAs in PC and discuss their potential as worthy diagnostic and prognostic biomarkers for PC, as well as their significance in PC pathogenesis and anticancer drug resistance.

A systems genomics approach to uncover patient-specific pathogenic pathways and proteins in ulcerative colitis

We describe a precision medicine workflow, the integrated single nucleotide polymorphism network platform (iSNP), designed to determine the mechanisms by which SNPs affect cellular regulatory networks, and how SNP co-occurrences contribute to disease pathogenesis in ulcerative colitis (UC). Using SNP profiles of 378 UC patients we map the regulatory effects of the SNPs to a human signalling network containing protein-protein, miRNA-mRNA and transcription factor binding interactions. With unsupervised clustering algorithms we group these patient-specific networks into four distinct clusters driven by PRKCB, HLA, SNAI1/CEBPB/PTPN1 and VEGFA/XPO5/POLH hubs. The pathway analysis identifies calcium homeostasis, wound healing and cell motility as key processes in UC pathogenesis. Using transcriptomic data from an independent patient cohort, with three complementary validation approaches focusing on the SNP-affected genes, the patient specific modules and affected functions, we confirm the regulatory impact of non-coding SNPs. iSNP identified regulatory effects for disease-associated non-coding SNPs, and by predicting the patient-specific pathogenic processes, we propose a systems-level way to stratify patients.

TGF-β1 induced proliferation, migration, and ECM accumulation through the SNHG11/miR-34b/LIF pathway in human pancreatic stellate cells

Chronic pancreatitis (CP) is a chronic inflammatory and fibrotic disease of the pancreas, and activated pancreatic stellate cells (PSCs) play a vital role in the progression of pancreatic fibrosis in CP. It has been reported that long non-coding RNA small nucleolar RNA host gene 11 (SNHG11) is highly expressed in chronic pancreatitis (CP) patients. However, the role of SNHG11 in CP progression is unclear. The purport of the study was to survey the role of SNHG11 in CP. We employed transforming growth factor (TGF)-beta1 (TGF-β1) to activate human pancreatic stellate cells (PSCs). Expression of SNHG11 was assessed with qRT-PCR. Loss-of-function experiments were executed to evaluate the effects of SNHG11 on the proliferation and migration of TGF-β1-treated PSCs. Some protein levels were detected by western blotting. The regulatory mechanism of SNHG11 was verified by the dual-luciferase reporter and RIP assays. As a result, SNHG11 was upregulated in plasma of CP patients and TGF-β1-treated PSCs. Also, SNHG11 inhibition reduced TGF-β1-induced proliferation, migration, and ECM accumulation in PSCs. Mechanistically, SNHG11 regulated leukemia inhibitory factor (LIF) expression by sponging miR-34b. Furthermore, miR-34b inhibitor abolished SNHG11 silencing-mediated effects on TGF-β1-treated PSC proliferation, migration, and ECM accumulation. LIF overexpression counteracted the repressive influence of miR-34b mimic on proliferation, migration, and ECM accumulation of TGF-β1-treated PSCs. In conclusion, SNHG11 knockdown reduced TGF-β1-induced PSC proliferation, migration, and ECM accumulation by the miR-34b/LIF axis.

Epithelial to Mesenchymal Transition: Key Regulator of Pancreatic Ductal Adenocarcinoma Progression and Chemoresistance

Simple Summary

Pancreatic ductal adenocarcinoma’s (PDAC) dismal prognosis is associated with its aggressive biological behavior and resistance to chemotherapy. Epithelial to mesenchymal transition (EMT) has been recognized as a key driver of PDAC progression and development of drug resistance. EMT is a transient and reversible process leading to transdifferentiation of epithelial cells into a more mesenchymal phenotype. It is regulated by multiple signaling pathways that control the activity of a transcription factors network. Activation of EMT in pre-invasive stages of PDAC has been accused for early dissemination. Furthermore, it contributes to the development of intratumoral heterogeneity and drug resistance. This review summarizes the available data regarding signaling networks regulating EMT and describes the integral role of EMT in different aspects of PDAC pathogenesis.

Abstract

Pancreatic ductal adenocarcinoma (PDAC) is one of the deadliest malignancies, characterized by aggressive biological behavior and a lack of response to currently available chemotherapy. Emerging evidence has identified epithelial to mesenchymal transition (EMT) as a key driver of PDAC progression and a central regulator in the development of drug resistance. EMT is a reversible transdifferentiation process controlled by complex interactions between multiple signaling pathways such as TGFb, Wnt, and Notch, which converge to a network of specific transcription factors. Activation of EMT transcriptional reprogramming converts cancer cells of epithelial differentiation into a more mesenchymal phenotypic state. EMT occurrence in pre-invasive pancreatic lesions has been implicated in early PDAC dissemination. Moreover, cancer cell phenotypic plasticity driven by EMT contributes to intratumoral heterogeneity and drug tolerance and is mechanistically associated with the emergence of cells exhibiting cancer stem cells (CSCs) phenotype. In this review we summarize the available data on the signaling cascades regulating EMT and the molecular isnteractions between pancreatic cancer and stromal cells that activate them. In addition, we provide a link between EMT, tumor progression, and chemoresistance in PDAC.

Non-coding RNAs in pancreatic ductal adenocarcinoma: New approaches for better diagnosis and therapy

Pancreatic ductal adenocarcinoma (PDAC) is one of the most aggressive malignancies with a 5-year survival rate less than 8%, which has remained unchanged over the last 50 years. Early detection is particularly difficult due to the lack of disease-specific symptoms and a reliable biomarker. Multimodality treatment including chemotherapy, radiotherapy (used sparingly) and surgery has become the standard of care for patients with PDAC. Carbohydrate antigen 19-9 (CA 19-9) is the most common diagnostic biomarker; however, it is not specific enough especially for asymptomatic patients. Non-coding RNAs are often deregulated in human malignancies and shown to be involved in cancer-related mechanisms such as cell growth, differentiation, and cell death. Several micro, long non-coding and circular RNAs have been reported to date which are involved in PDAC. Aim of this review is to discuss the roles and functions of non-coding RNAs in diagnosis and treatments of PDAC.

The risk of pancreatic adenocarcinoma following SARS-CoV family infection

COVID 19 disease has become a global catastrophe over the past year that has claimed the lives of over two million people around the world. Despite the introduction of vaccines against the disease, there is still a long way to completely eradicate it. There are concerns about the complications following infection with SARS-CoV-2. This research aimed to evaluate the possible correlation between infection with SARS-CoV viruses and cancer in an in-silico study model. To do this, the relevent dataset was selected from GEO database. Identification of differentially expressed genes among defined groups including SARS-CoV, SARS-dORF6, SARS-BatSRBD, and H1N1 were screened where the |Log FC| ≥ 1and p < 0.05 were considered statistically significant. Later, the pathway enrichment analysis and gene ontology (GO) were used by Enrichr and Shiny GO databases. Evaluation with STRING online was applied to predict the functional interactions of proteins, followed by Cytoscape analysis to identify the master genes. Finally, analysis with GEPIA2 server was carried out to reveal the possible correlation between candidate genes and cancer development. The results showed that the main molecular function of up- and down-regulated genes was "double-stranded RNA binding" and actin-binding, respectively. STRING and Cytoscape analysis presented four genes, PTEN, CREB1, CASP3, and SMAD3 as the key genes involved in cancer development. According to TCGA database results, these four genes were up-regulated notably in pancreatic adenocarcinoma. Our findings suggest that pancreatic adenocarcinoma is the most probably malignancy happening after infection with SARS-CoV family.

Crosstalk between miRNAs and signaling pathways involved in pancreatic cancer and pancreatic ductal adenocarcinoma

Pancreatic cancer (PC) is the seventh leading cause of cancer-related deaths worldwide with 5-year survival rates below 8%. Most patients with PC and pancreatic ductal adenocarcinoma (PDAC) die after relapse and cancer progression as well as resistance to treatment. Pancreatic tumors contain a high desmoplastic stroma that forms a rigid mass and has a potential role in tumor growth and metastasis. PC initiates from intraepithelial neoplasia lesions leading to invasive cancer through various pathways. These lesions harbor particular changes in signaling pathways involved in the tumorigenesis process. These events affect both the epithelial cells, including the tumor and the surrounding stroma, and eventually lead to the formation of complex signaling networks. Genetic studies of PC have revealed common molecular features such as the presence of mutations in KRAS gene in more than 90% of patients, as well as the inactivation or deletion mutations of some tumor suppressor genes including TP53, CDKN2A, and SMAD4. In recent years, studies have also identified different roles of microRNAs in PC pathogenesis as well as their importance in PC diagnosis and treatment, and their involvement in various signaling pathways. In this study, we discussed the most common pathways involved in PC and PDAC as well as their role in tumorigenesis and progression. Furthermore, the miRNAs participating in the regulation of these signaling pathways in PC progression are summarized in this study. Therefore, understanding more about pathways involved in PC can help with the development of new and effective therapies in the future.

Piperlongumine inhibits the growth of non-small cell lung cancer cells via the miR-34b-3p/TGFBR1 pathway

BACKGROUND

Non-small cell lung cancer is a common type of lung cancer. Piperlongumine (PL), which is extracted from the roots of piperaceae plant, long pepper, and peppercorn, is an alkaloid amide that inhibits tumor growth and metastasis. However, whether it affects lung cancer cells remains unclear.

METHODS

We assessed the effects of PL on the proliferation and apoptosis of A549 and H1299 NSCLC cell lines.

RESULTS

PL was mildly toxic to normal human bronchial epithelial cells and significantly suppressed growth and facilitated apoptosis of A549 and H1299 cells. It also upregulated microRNA (miR)-34b-3p and downregulated the transforming growth factor beta type I receptor (TGFBR1). The dual-luciferase reporter assay showed that TGFBR1 is a target gene of miR-34b-3p. Silencing of miR-34b-3p or overexpression of TGFBR1 partially attenuated the effects of PL on A549 and H1299 cells.

CONCLUSIONS

PL inhibits proliferation and induces apoptosis of A549 and H1299 cells by upregulating miR-34b-3p and modulating TGFBR1 signaling pathway.

A traditional Chinese medicine formula inhibits tumor growth in mice and regulates the miR-34b/c-Met/β-catenin pathway

ETHNOPHARMACOLOGY RELEVANCE

Si-Jun-Zi-Tang (SJZT) is a traditional Chinese medicine formula used to treat chronic and debilitating diseases including melanoma. SJZT-based therapies have achieved good clinical outcomes in melanoma management. However, the pharmacological basis of SJZT for its clinical use in melanoma treatment is not fully understood.

AIM OF THE STUDY

To investigate the anti-melanoma effects and mechanism of action of an ethanolic extract of SJZT.

MATERIALS AND METHODS

SJZT was extracted using 50% ethanol. A murine B16 melanoma-bearing mouse model was employed to investigate the anti-melanoma effects of SJZT. microRNA (miRNA) and mRNA levels were examined by RT-qPCR, and protein levels were measured by Western blotting.

RESULTS

SJZT significantly inhibited B16 tumor growth in mice. Mechanistic investigations revealed that SJZT elevated miR-34b (a tumor suppressing miRNA), and lowered c-Met (a miR-34b target gene) and β-catenin (a downstream molecule of c-Met signaling) expression levels in the B16 tumors.

CONCLUSIONS

In this study we found, for the first time, that SJZT exerts anti-melanoma effects and regulates the miR-34b/c-Met/β-catenin pathway in a melanoma mouse model. Our findings provide pharmacological justifications for the clinical use of SJZT in treating melanoma.

Exosomal miR-34b inhibits proliferation and the epithelial-mesenchymal transition by targeting Notch2 in ovarian cancer

Exosomal microRNA (miR) can affect signaling pathways in various physiological and pathological conditions, including ovarian cancer (OC). miR-34b, the first microRNA targeted in a human clinical trial for cancer treatment, exhibited decreased expression in several cancer types. However, the biological function of exosomal miR-34b in OC has not been elucidated. In the present study, using reverse transcription-quantitative PCR, it was reported that exosomal miR-34b is downregulated in OC cells. Exosomal miR-34b reduced cell proliferation and epithelial-mesenchymal transition (EMT) in the OC cell line SKOV3. In addition, it was confirmed that Notch2, which is upregulated in SKOV3 cells, is a target of miR-34b. Moreover, exosomal miR-34b and Notch2 levels were found to be negatively correlated. The present data highlights the importance of exosomal miR-34b-mediated inhibition of cell proliferation and EMT, suggesting that exosomal miR-34b has value as a diagnostic biomarker and a potential molecular target for the treatment of OC.

Prognostic value of microRNAs in pancreatic cancer: a meta-analysis

BACKGROUND

The prognostic impact of microRNA (miRNA) expression levels in pancreatic cancer (PC) has been estimated for years, but the outcomes are controversial and heterogeneous. Therefore, we comprehensively reviewed the evidence collected on miRNA expression in PC to determine this effect.

RESULTS

PC patients with high miR-21 (HR=2.61, 95%CI=1.68-4.04), miR-451a (HR=2.23, 95%CI=1.23-4.04) or miR-1290 (HR=1.43, 95%CI=1.04-1.95) levels in blood had significantly poorer OS (P<0.05). Furthermore, PC patients with high miR-10b (HR=1.73, 95%CI=1.09-2.76), miR-17-5p (HR=1.91, 95%CI=1.30-2.80), miR-21 (HR=1.90, 95%CI=1.61-2.25), miR-23a (HR=2.18, 95%CI=1.52-3.13), miR-155 (HR=2.22, 95%CI=1.27-3.88), miR-203 (HR=1.65, 95%CI=1.14-2.40), miR-221 (HR=1.72, 95%CI=1.08-2.74), miR-222 levels (HR=1.72, 95%CI=1.02-2.91) or low miR-29c (HR=1.39, 95%CI=1.08-1.79), miR-126 (HR=1.55, 95%CI=1.23-1.95), miR-218 (HR=2.62, 95%CI=1.41-4.88) levels in tissues had significantly shorter OS (P<0.05).

CONCLUSIONS

In summary, blood miR-21, miR-451a, miR-1290 and tissue miR-10b, miR-17-5p, miR-21, miR-23a, miR-29c, miR-126, miR-155, miR-203, miR-218, miR-221, miR-222 had significant prognostic value.

METHODS

We searched PubMed, EMBASE, Web of Science and Cochrane Database of Systematic Reviews to recognize eligible studies, and 57 studies comprising 5445 PC patients and 15 miRNAs were included to evaluate the associations between miRNA expression levels and overall survival (OS) up to June 1, 2019. Summary hazard ratios (HR) with 95% confidence intervals (CI) were calculated to assess the effect.

MicroRNAs mediate the anti-tumor and protective effects of ginsenosides

MicroRNAs (miRs(, as short non-coding RNAs, regulate important biological processes and mainly are associated with regulation of gene expression. The miRs are beneficial targets for diagnosis of various disorders, particularly cancer, since their expression profile undergoes alterations in pathological conditions. The numerous drugs have been designed with the capability of targeting miRs for treating pathological conditions. On the other hand, the application of naturally occurring compounds has been increased due to their minimal side effects and valuable biological and therapeutic activities. Ginsenosides are able to act as anti-tumor agents via either increasing or decreasing the expression level of miRs. Ginsenosides affect the expression profile of miRNAs to induce their protective impacts. Angiogenesis as a key factor in the progression of cancer can be suppressed by ginsenosides which is mediated by miR regulation. The aim of this review is to shed some light on the protective and anti-tumor activities of ginsenosides mediated by miRNAs.

Proteogenomic Network Analysis of Context-Specific KRAS Signaling in Mouse-to-Human Cross-Species Translation

The highest frequencies of KRAS mutations occur in colorectal carcinoma (CRC) and pancreatic ductal adenocarcinoma (PDAC). The ability to target downstream pathways mediating KRAS oncogenicity is limited by an incomplete understanding of the contextual cues modulating the signaling output of activated K-RAS. We performed mass spectrometry on mouse tissues expressing wild-type or mutant Kras to determine how tissue context and genetic background modulate oncogenic signaling. Mutant Kras dramatically altered the proteomes and phosphoproteomes of preneoplastic and neoplastic colons and pancreases in a context-specific manner. We developed an approach to statistically humanize the mouse networks with data from human cancer and identified genes within the humanized CRC and PDAC networks synthetically lethal with mutant KRAS. Our studies demonstrate the context-dependent plasticity of oncogenic signaling, identify non-canonical mediators of KRAS oncogenicity within the KRAS-regulated signaling network, and demonstrate how statistical integration of mouse and human datasets can reveal cross-species therapeutic insights.

MicroRNA in Pancreatic Cancer: From Biology to Therapeutic Potential

Pancreatic cancer is one of the most aggressive malignancies, accounting for more than 45,750 deaths annually in the U.S. alone. The aggressive nature and late diagnosis of pancreatic cancer, coupled with the limitations of existing chemotherapy, present the pressing need for the development of novel therapeutic strategies. Recent reports have demonstrated a critical role of microRNAs (miRNAs) in the initiation, progression, and metastasis of cancer. Furthermore, aberrant expressions of miRNAs have often been associated with the cause and consequence of pancreatic cancer, emphasizing the possible use of miRNAs in the effective management of pancreatic cancer patients. In this review, we provide a brief overview of miRNA biogenesis and its role in fundamental cellular process and miRNA studies in pancreatic cancer patients and animal models. Subsequent sections narrate the role of miRNA in, (i) cell cycle and proliferation; (ii) apoptosis; (iii) invasions and metastasis; and (iv) various cellular signaling pathways. We also describe the role of miRNA's in pancreatic cancer; (i) diagnosis; (ii) prognosis and (iii) therapeutic intervention. Conclusion section describes the gist of review with future directions.

HDL protects against myocardial ischemia reperfusion injury via miR-34b and miR-337 expression which requires STAT3

Purpose

High density lipoprotein (HDL) protects against myocardial infarction via mechanisms that remain unclear. STAT3 (signal transducer and activator of transcription 3) plays a key role in HDL-induced cardioprotection. In the heart, microRNAs (miRNAs) are involved in ischemia reperfusion injury. We therefore investigated whether the cardioprotective effect of HDL modulates miRNAs as a downstream target of STAT3 activation.

Methods

STAT3 cardiomyocyte deficient mice (STAT3-KO) and wildtype littermates (STAT3-WT) were submitted to left coronary ligature and reperfused (IR) with or without injection of HDL. Infarct size (IS) was determined and cardiac miRNA expression was evaluated after reperfusion in sham, IR and IR+HDL hearts by microarray analysis.

In vitro, neonatal rat ventricular cardiomyocytes were submitted to hypoxia with or without HDL incubation. Cell viability and miRNA expression were analysed.

Results

In vivo, HDL reduced IS from 40.5±4.3% to 24.4±2.1% (p<0.05) in STAT3-WT mice. HDL failed to protect in STAT3-KO mice. In STAT3-WT mice, both miR-34b and miR-337 were increased in IR compared to sham and IR+HDL groups (p<0.05). These miRNAs were not modulated in STAT3-KO mice. In vitro, incubation with HDL improved cell viability against hypoxia (p<0.05). The expression of miR-34b and miR-337 was increased by hypoxia and reduced by HDL treatment (p<0.05). In cardiomyocytes transfected with miRNA mimics, HDL failed to improve cell viability against hypoxia.

Conclusions

Our study, performed both in vivo and in vitro, delineates a novel cardioprotective signalling pathway activated by HDL, involving STAT3-mediated decrease of miR-34b and miR-337 expression.

Dysregulation of key microRNAs in pancreatic cancer development

Pancreatic cancer (PC) is mentioned as one of the fourth major cause of cancer-related deaths and also is considered as one of the most malignancies worldwide. Sadly, widely metastasis is frequently observed at the time of PC detection and there are, thereby, almost poor prognosis and ineffective treatment in PC patients. microRNAs (miRNAs), a group of short non-coding RNAs, regulate various cellular and developmental mechanisms, such as cell growth, proliferation, apoptosis, differentiation and angiogenesis. Also, they have essential roles even on the progression of different human and animal diseases. In recent years, extensive studies confirmed the important role of miRNAs in various steps of PC developments, including; tumor initiation, invasion and metastasis, which can use valuably for cancer detection, prognosis and therapy. Therefore, the present study reviewed the new recent investigations in miRNAs involvement in the biology of PC associated with their clinical implications.

MicroRNAs in pancreatic cancer diagnosis and therapy

Pancreatic cancer remains a disease with very poor prognosis (only 5-6% of patients are still alive after five years). Attempts to improve the results of treatment of pancreatic cancer focus on a better understanding of the pathogenesis, and non-invasive diagnostic methods (genetic testing from peripheral blood), which would create the possibility of early diagnosis and early surgical treatment before the onset of metastasis. New hopes for the improvement of early diagnosis and treatment of pancreatic ductal adenocarcinoma (PDAC) are associated with genetic testing of microRNA expression changes. A large body of evidence has revealed that microRNAs are aberrantly expressed in the serum and in cancer tissues and elicit oncogenic or tumour-suppressive functions. Selected microRNAs can distinguish pancreatic ductal adenocarcinoma from non-cancerous lesions of the pancreas. This review focuses on the involvement of microRNAs in the early diagnosis of pancreatic cancer. Research results related to the development of a novel therapeutic strategy based on the modulation of microRNA expressions for a better outcome in patients with pancreatic cancer are also presented.

EZH2-Mediated microRNA-139-5p Regulates Epithelial-Mesenchymal Transition and Lymph Node Metastasis of Pancreatic Cancer

Pancreatic cancer (PC) is one of the most aggressive cancers presenting with high rates of invasion and metastasis, and unfavorable prognoses. The current study aims to investigate whether EZH2/miR-139-5p axis affects epithelial-mesenchymal transition (EMT) and lymph node metastasis (LNM) in PC, and the mechanism how EZH2 regulates miR-139-5p. Human PC and adjacent normal tissues were collected to determine expression of EZH2 and miR-139-5p, and their relationship with clinicopathological features of PC. Human PC cell line was selected, and treated with miR-139-5p mimics/inhibitors, EZH2 vector or shEZH2 in order to validate the regulation of EZH2-mediated miR-139-5p in PC cells. Dual-luciferase report gene assay and chromatin immunoprecipitation assay were employed to identify the relationship between miR-139-5p and EZH2. RT-qPCR and Western blot analysis were conducted to determine the expression of miR-139-5p, EZH2 and EMT-related markers and ZEB1/2. Tumor formation ability and in vitro cell activity were also analyzed. Highly-expressed EZH2 and poorly-expressed miR-139-5p were detected in PC tissues, and miR-139-5p and EZH2 expressions were associated with patients at Stage III/IV, with LNM and highly-differentiated tumors. EZH2 suppressed the expression of miR-139-5p through up-regulating Histone 3 Lysine 27 Trimethylation (H3K27me3). EMT, cell proliferation, migration and invasion were impeded, and tumor formation and LNM were reduced in PC cells transfected with miR-139-5p mimics and shEZH2. MiR-139-5p transcription is inhibited by EZH2 through up-regulating H3K27me3, thereby down-regulation of EZH2 and up-regulation of miR-139-5p impede EMT and LNM in PC. In addition, the EZH2/miR-139-5p axis presents as a promising therapeutic strategy for the treatment of PC.

Which patients with para-aortic lymph node (LN16) metastasis will truly benefit from curative pancreaticoduodenectomy for pancreatic head cancer?

In patients with cancer of the pancreatic head, metastasis to para-aortic lymph nodes (LN16) is considered distant metastasis and a poor prognostic marker. However, the incidence of LN16 involvement in pancreatic head cancer is high, and it is unclear whether all such patients have poor surgical outcomes. We investigated the significance of LN16 involvement in resectable pancreatic head cancer by retrospectively analyzing 579 ductal adenocarcinoma patients treated with para-aortic lymph node dissection at two high-volume Chinese centers. Depending upon tumor location, the incidence of LN16 metastasis and the correlation between LN16 involvement and involvement of Group 1 or 2 lymph nodes significantly differed. Metastasis to LN16 indicated a high serum tumor burden and a poor prognosis, though LN16-positive patients with a lymph node ratio (LNR) < 0.25 may still benefit from radical surgery. Survival analysis of LN16-positive patients with resectable pancreatic head cancer revealed that tumor size, tumor differentiation, and tumor location are independent prognostic factors. We also found that preoperative serum CA125 < 18.62 U/ml and the level of JAK2 signaling are both indicators of who may benefit from curative surgical resection for pancreatic head cancer.

S-adenosylmethionine and methylthioadenosine inhibit cancer metastasis by targeting microRNA 34a/b-methionine adenosyltransferase 2A/2B axis

MicroRNA-34a (miR-34a) is down-regulated in colorectal cancers (CRC) and required for interleukin-6 (IL-6)-induced CRC metastasis. Mice lacking miR-34a developed more invasive cancer in a colitis-associated cancer model. In the same model, S-adenosylmethionine (SAMe) and methylthioadenosine (MTA) inhibited IL-6/STAT3 and lowered tumor burden. SAMe and MTA reduce the expression of methionine adenosyltransferase 2A (MAT2A) and there are consensus binding sites for miR-34a/b in the MAT2A 3’UTR. Here we examined whether SAMe/MTA influence miR-34a/b expression and cancer metastasis. We found SAMe and MTA raised miR-34a/b expression in CRC cell lines, inhibited migration and invasion in vitro and liver metastasis in vivo. Like CRC, MAT2A and MAT2B expression is induced in human pancreas and prostate cancers. Treatment with SAMe, MTA, miR-34a or miR-34b inhibited MAT2A expression mainly at the protein level. MAT2B protein level also fell because MAT2A and MAT2B enhance each other’s protein stability. Overexpressing miR-34a or miR-34b inhibited while MAT2A or MAT2B enhanced CRC migration and invasion. Co-expressing either miR-34a/b had minimal to no effect on MAT2A/MAT2B’s ability to increase migration, invasion and growth. Taken together, MAT2A and MAT2B are important targets of miR-34a/b and SAMe and MTA target this axis, suppressing MAT2A/MAT2B while raising miR-34a/b expression, inhibiting cancer metastasis.

Pancreatic Ductal Adenocarcinoma: Current and Evolving Therapies

Pancreatic ductal adenocarcinoma (PDAC), which constitutes 90% of pancreatic cancers, is the fourth leading cause of cancer-related deaths in the world. Due to the broad heterogeneity of genetic mutations and dense stromal environment, PDAC belongs to one of the most chemoresistant cancers. Most of the available treatments are palliative, with the objective of relieving disease-related symptoms and prolonging survival. Currently, available therapeutic options are surgery, radiation, chemotherapy, immunotherapy, and use of targeted drugs. However, thus far, therapies targeting cancer-associated molecular pathways have not given satisfactory results; this is due in part to the rapid upregulation of compensatory alternative pathways as well as dense desmoplastic reaction. In this review, we summarize currently available therapies and clinical trials, directed towards a plethora of pathways and components dysregulated during PDAC carcinogenesis. Emerging trends towards targeted therapies as the most promising approach will also be discussed.

miRNA-708 functions as a tumour suppressor in hepatocellular carcinoma by targeting SMAD3

Hepatocellular carcinoma (HCC) is the most frequent subtype of primary liver cancer and the third most common cause of cancer-associated mortality worldwide. Previous studies have reported that microRNAs (miRNAs) serve key roles in the carcinogenesis and progression of HCC by regulating gene expression. The present study investigated the expression patterns, biological roles and underlying mechanisms of miRNA-708 (miR-708) in HCC. The expression levels of miR-708 in HCC tissue samples and cell lines were examined. Cell proliferation, migration and invasion assays were used to evaluate the effect of miR-708 on HCC cells. In addition, bioinformatic and western blotting analyses, and dual luciferase reporter assays were performed to investigate the direct gene target of miR-708. The results of the present study demonstrated that miR-708 expression was significantly decreased in HCC tissue samples and cell lines. In addition, the expression level of miR-708 was associated with increased HCC tumour stage. Furthermore, ectopic expression of miR-708 suppressed HCC cell proliferation, migration and invasion. The results of the present study also indicated that miR-708 targets SMAD family member 3 directly in vitro. The results of the present study indicated that miR-708 may be a novel target for future HCC therapy.

Ginsenoside Rd attenuates breast cancer metastasis implicating derepressing microRNA-18a-regulated Smad2 expression

Metastasis remains a major cause of mortality and poor prognosis in breast cancer patients. Anti-metastatic therapies are in great need to achieve optimal clinical outcome in breast cancer patients. Panax Notoginseng Saponins (PNS) has previously been shown to inhibit breast cancer metastasis in mouse. Here the potential anti-metastatic effect of one of the chemical compounds of PNS, ginsenoside Rd (Rd), was further evaluated in mouse mammary carcinoma 4T1 cells. The results revealed that Rd treatment dose-dependently suppressed cell migration and invasion in cultured 4T1 cells. In 4T1 cell-inoculated mice, Rd treatment led to decreased number of tumor lesions in lungs in both spontaneous and experimental metastasis models. Rd treatment resulted in increased expression of Smad2 in cultured 4T1 cells and in tumors grown from inoculated 4T1 cells. Rd treatment decreased the expression of microRNA (miR)-18a in cultured 4T1 cells and in tumors derived from inoculated 4T1 cells. Smad2 was further verified to be a direct target of miR-18a in 4T1 cells. The significant impact of Rd on counteracting miR-18a-medidated downregulation of Smad2 expression was also demonstrated. Together, the current work shows for the first time that Rd treatment attenuates breast cancer metastasis in part through derepressing miR-18a-mediated Smad2 expression regulation.

The Role of MicroRNAs and Their Targets in Osteoarthritis

Micro ribonucleic acid (microRNA) regulation and expression has become an emerging field in determining the mechanisms regulating a variety of inflammation-mediated diseases. Several studies have focused on specific microRNAs that are differentially expressed in cases of osteoarthritis. Furthermore, several targets of these miRNAs important in disease progression have also been identified. In this review, we focus on microRNA biogenesis, regulation, detection, and quantification with an emphasis on cellular localization and how these concepts may be linked to disease processes such as osteoarthritis. Next, we review the relationships of specific microRNAs to certain features and risk factors associated with osteoarthritis such as inflammation, obesity, autophagy, and cartilage homeostasis. We also identify certain microRNAs that are differentially expressed in osteoarthritis but have unidentified targets and functions in the disease state. Lastly, we identify the potential use of microRNAs for therapeutic purposes and also mention certain remedies that regulate microRNA expression.

Identification of a microRNA (miR-663a) induced by ER stress and its target gene PLOD3 by a combined microRNome and proteome approach

INTRODUCTION

MicroRNAs (miRs) regulate gene expression to support important physiological functions. Significant evidences suggest that miRs play a crucial role in many pathological events and in the cell response to various stresses.

METHODS

With the aim to identify new miRs induced by perturbation of intracellular calcium homeostasis, we analysed miR expression profiles of thapsigargin (TG)-treated cells by microarray. In order to identify miR-663a-regulated genes, we evaluated proteomic changes in miR-663a-overexpressing cells by two-dimensional differential in-gel electrophoresis coupled to mass spectrometric identification of the differentially represented proteins. Microarray and proteomic analyses were supported by biochemical validation.

RESULTS

Results of microarray revealed 24 differentially expressed miRs; among them, miR-663a turned out to be by ER stress and under the control of the PERK pathway of the unfolded protein response. Proteomic analysis revealed that PLOD3, which is the gene encoding for collagen-modifying lysyl hydroxylase 3 (LH3), is regulated by miR-663a. Luciferase reporter assays demonstrated that miR-663a indeed reduces LH3 expression by targeting to 3'-UTR of PLOD3 mRNA. Interestingly, miR-663a inhibition of LH3 expression generates reduced extracellular accumulation of type IV collagen, thus suggesting the involvement of miR-663a in modulating collagen 4 secretion in physiological conditions and in response to ER stress.

CONCLUSION

The finding of the ER stress-induced PERK-miR-663a pathway may have important implications in the understanding of the molecular mechanisms underlying the function of this miR in normal and/or pathological conditions.

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.

Clinical significance of microRNA-34b expression in pediatric acute leukemia

The present study aimed to explore the function of miR‑34b promoter methylation in cell proliferation in children's acute leukemia. Quantitative PCR and methylation‑specific PCR were performed to measure the levels of miR‑34b and its promoter methylation in normal cells, eight leukemia cell lines as well as primary leukemic cells isolated from patients newly diagnosed with acute lymphoblastic leukemia (ALL), acute myeloid leukemia (AML) and mixed lymphocytic lymphoma. miR‑34b levels in leukemia cell lines and primary leukemic cells were significantly lower than those in normal cells. The miR‑34b promoter was found to be methylated in all leukemia cell lines, 24 of 31 ALL patients and 8 of 19 AML patients, but not in the 23 normal controls. miR‑34b expression and methylation of its promoter were not associated with most clinical parameters assessed; however, miR‑34b levels in prednisone‑sensitive ALL were significantly different from those in insensitive ALL. A cell counting kit‑8 assay showed that transfection of miR‑34b mimics into K562 cells inhibited their proliferation. Furthermore, treatment with the demethylating agent 5‑aza‑2‑deoxycytidine significantly enhanced miR‑34b expression levels and decreased the methylation status of its promoter in HL‑60 and K562 cells. In conclusion, the results of the present study indicated that in pediatric leukemia cells and leukemia cell lines, the expression of miR‑34b is inhibited by methylation of its promoter, which impairs the restraining effects of miR‑34b on cell proliferation. It was also indicated that the expression of miR‑34b in ALL patients may affect their response to early treatments.

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.

Emerging roles of microRNAs in pancreatic cancer diagnosis, therapy and prognosis (Review)

Pancreatic cancer is one of the leading causes of cancer related death. Increasing incidence and mortality indicates a lack of detection and post diagnostic management of this disease. Recent evidences suggest that, miRNAs are very attractive target molecules that can serve as biomarkers for predicting development and progression of pancreatic cancer. Furthermore, miRNAs are also promising therapeutic targets for pancreatic cancer. The objective of the present review is to discuss the significance of miRNA in pancreatic cancer development, diagnosis, therapy and prognosis. We extracted and compiled the useful information from PubMed database, which satisfied our criteria for analysis of miRNAs in pancreatic cancer diagnosis, therapy and prognosis. A summary of the most important miRNAs known to regulate pancreatic tumorigenesis is provided. The review also provides a collection of evidence that show miRNA profiles of biofluids hold much promise for use as biomarkers to predict and detect development of pancreatic cancer in its early stages. Identification of key miRNA networks in pancreatic cancer will provide long-awaited diagnostic/therapeutic/prognostic tools for early detection, better treatment options, and extended life expectancy and quality of life in PDAC patients.

miRNA-mRNA crosstalk in esophageal cancer: From diagnosis to therapy

The asymptomatic nature of esophageal cancer (EC) at early stages results in late clinical presentation leading to poor prognosis and limited success of therapeutic modalities. Efforts to identify diagnostic/prognostic markers have proven to be unsuccessful for translation into clinics. Hence, there is a pressing need for establishment of novel non-invasive biomarker for early diagnosis/better prognosis of EC. Recently, alteration in microRNA (miRNA) expression has emerged as an important hallmark of cancer. This review summarizes the differential expression of miRNAs in EC and addresses how their aberrant expression influences crucial biological processes such as apoptosis, cell proliferation, invasion and metastasis. Additionally, this review highlights the current status of circulating miRNA based diagnostic/prognostic markers. An effort has been made to find a connection between different miRNAs involved in EC and a detailed analysis has been done to screen out micoRNAs involved in prognosis and multidrug resistance. Further, investigation of these miRNAs would not only provide a gene therapy based strategy to prevent/treat cancer but also to reverse multidrug resistance leading to decreased requirement of harmful chemotherapeutic drugs.

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

BACKGROUND

Reports have described the prognostic relevance of microRNAs (miRNAs) in patients treated for pancreatic ductal adenocarcinoma (PDAC). However, many of these include small numbers of patients. To increase statistical power and improve translation, we performed a systematic review and meta-analysis to determine a pooled conclusion. We examined the impact of miRNAs on overall survival (OS) and disease-free survival (DFS) in PDAC.

METHODS

Eligible studies were identified and quality assessed using multiple search strategies (last search December 2014). Data were collected from studies correlating clinical outcomes with dysregulated tumoural or blood miRNAs. Studies were pooled, and combined hazard ratios (HRs) with 95% confidence intervals (CIs) were used to estimate strength of the associations.

RESULTS

Twenty studies involving 1525 patients treated for PDAC were included. After correcting for publication bias, OS was significantly shortened in patients with high tumoural miR-21 (adjusted HR = 2.48; 1.96-3.14). This result persisted when only studies adjusting for adjuvant chemotherapy were combined (adjusted HR = 2.72; 1.91-3.89). High miR-21 also predicted reduced DFS (adjusted HR = 3.08; 1.78-5.33). Similarly, we found significant adjusted HRs for poor OS for high miR-155, high miR-203, and low miR-34a; and unadjusted HRs for high miR-222 and high miR-10b. The small number of studies, limited number of miRNAs and paucity of multivariate analyses are the limitations of our study.

CONCLUSIONS

This is the first rigorous pooled analysis assessing miRNAs as prognostic biomarkers in PDAC. Tumoural miR-21 overexpression emerged as an important predictor of poor prognosis after PDAC resection independent of other clinicopathologic factors, including adjuvant chemotherapy use.

Noncoding RNAs as potential biomarkers to predict the outcome in pancreatic cancer

Pancreatic ductal adenocarcinoma (PDAC), a common digestive system cancer, is highly malignant and has a poor disease outcome. Currently, all available examination and detection methods cannot accurately predict the clinical outcome. Therefore, it is extremely important to identify novel molecular biomarkers for personalized medication and to significantly improve the overall outcome. The “noncoding RNAs” (ncRNAs) are a group of RNAs that do not code for proteins, and they are categorized as structural RNAs and regulatory RNAs. It has been shown that microRNAs and long ncRNAs function as regulatory RNAs to affect the progression of various diseases. Many studies have confirmed a role for ncRNAs in the progression of PDAC during the last few years. Because of the significant role of ncRNAs in PDAC, ncRNA profiling may be used to predict PDAC outcome with high accuracy. This review comprehensively analyzes the value of ncRNAs as potential biomarkers to predict the outcome in PDAC and the possible mechanisms thereof.

MiR-1178 promotes the proliferation, G1/S transition, migration and invasion of pancreatic cancer cells by targeting CHIP

CHIP, a co-chaperone protein that interacts with Hsc/Hsp70, has been shown to be under-expressed in pancreatic cancer cells and has demonstrated a potential tumor suppressor property. Nevertheless, the underlying mechanisms of CHIP regulation in pancreatic cancer cells remain unknown. In this study, we found that miR-1178 decreased the translation of the CHIP protein by targeting the 3′-UTR region. We observed that over-expression of miR-1178 facilitated the proliferation, G1/S transition, migration and invasion of pancreatic cancer cells. Conversely, the inhibition of miR-1178 expression significantly suppressed these phenotypes. Furthermore, CHIP over-expression abrogated miR-1178-induced cell proliferation and invasion. Our data suggest that miR-1178 acts as an oncomiR in pancreatic cancer cells by inhibiting CHIP expression.

Contribution of bioinformatics prediction in microRNA-based cancer therapeutics

Despite enormous efforts, cancer remains one of the most lethal diseases in the world. With the advancement of high throughput technologies massive amounts of cancer data can be accessed and analyzed. Bioinformatics provides a platform to assist biologists in developing minimally invasive biomarkers to detect cancer, and in designing effective personalized therapies to treat cancer patients. Still, the early diagnosis, prognosis, and treatment of cancer are an open challenge for the research community. MicroRNAs (miRNAs) are small non-coding RNAs that serve to regulate gene expression. The discovery of deregulated miRNAs in cancer cells and tissues has led many to investigate the use of miRNAs as potential biomarkers for early detection, and as a therapeutic agent to treat cancer. Here we describe advancements in computational approaches to predict miRNAs and their targets, and discuss the role of bioinformatics in studying miRNAs in the context of human cancer.

Insights into the Role of microRNAs in Pancreatic Cancer Pathogenesis: Potential for Diagnosis, Prognosis, and Therapy

Pancreatic cancer is a highly lethal malignancy and a fourth leading cause of cancer-related death in the United States. Poor survival of pancreatic cancer patients is largely because of its asymptomatic progression to advanced stage against which no effective therapy is currently available. Over the years, we have developed significant knowledge of molecular progression of pancreatic cancer and identified several genetic and epigenetic aberrations to be involved in its etiology and aggressive behavior. In that regard, recent lines of evidence have suggested important roles of microRNAs (miRNAs/miRs) in pancreatic cancer pathogenesis. microRNAs belonging to a family of small, noncoding RNAs are able to control diverse biological processes due to their ability to regulate gene expression at the posttranscriptional level. Accordingly, dysregulation of miRNAs can lead to several disease conditions, including cancer. There is a long list of microRNAs that exhibit aberrant expression in pancreatic cancer and serve as key microplayers in its initiation, progression, metastasis, and chemoresistance. These findings have suggested that microRNAs could be exploited as novel biomarkers for diagnostic and prognostic assessments of pancreatic cancer and as targets for therapy. This book chapter describes clinical problems associated with pancreatic cancer, roles that microRNAs play in various aspects of pancreatic cancer pathogenesis, and envision opportunities for potential use of microRNAs in pancreatic cancer management.

Epithelial-mesenchymal transition in pancreatic cancer: Is it a clinically significant factor?

Pancreatic cancer is one of the most aggressive solid malignancies. This aggressiveness is partly attributable to extensive local tumor invasion and early systemic dissemination as well as resistance to chemotherapy. Epithelial-mesenchymal transition (EMT) plays fundamental roles in embryonic development and in the differentiation of normal tissues and organs. EMT also plays critical roles in tumor formation, dissemination and drug resistance in pancreatic cancer. Emerging data suggest that inhibiting EMT may reverse the EMT phenotype and enhance the efficacy of chemotherapeutic agents against pancreatic cancer cells. Thus, an understanding of the molecular biology of EMT in pancreatic cancer may provide insights into the mechanisms of tumor invasion and metastatic progression and facilitate the development of alternative therapeutic approaches to improve the treatment outcomes for patients suffering from pancreatic cancer.

Stathmin destabilizing microtubule dynamics promotes malignant potential in cancer cells by epithelial-mesenchymal transition

BACKGROUND

Stathmin is a ubiquitous cytosolic regulatory phosphoprotein and is overexpressed in different human malignancies. The main physiological function of stathmin is to interfere with microtubule dynamics by promoting depolymerization of microtubules or by preventing polymerization of tubulin heterodimers. Stathmin plays important roles in regulating many cellular functions as a result of its microtubule-destabilizing activity. Currently, the critical roles of stathmin in cancer cells, as well as in lymphocytes have been valued. This review discusses stathmin and microtubule dynamics in cancer development, and hypothesizes their possible relationship with epithelial-mesenchymal transition (EMT).

DATA SOURCES

A PubMed search using such terms as "stathmin", "microtubule dynamics", "epithelial-mesenchymal transition", "EMT", "malignant potential" and "cancer" was performed to identify relevant studies published in English. More than 100 related articles were reviewed.

RESULTS

The literature clearly documented the relationship between stathmin and its microtubule-destabilizing activity of cancer development. However, the particular mechanism is poorly understood. Microtubule disruption is essential for EMT, which is a crucial process during cancer development. As a microtubule-destabilizing protein, stathmin may promote malignant potential in cancer cells by initiating EMT.

CONCLUSIONS

We propose that there is a stathmin-microtubule dynamics-EMT (S-M-E) axis during cancer development. By this axis, stathmin together with its microtubule-destabilizing activity contributes to EMT, which stimulates the malignant potential in cancer cells.

MicroRNAs in pancreatic malignancy: progress and promises

Despite progress in recent years, pancreatic cancer still remains a major clinical challenge. Its incidence and mortality rates have been on consistent rise underscoring the critical need for novel diagnostic, prognostic and therapeutic tools for its effective management. Recent studies have demonstrated that microRNAs (miRNAs/miRs) are deregulated in a variety of malignancies, including pancreatic cancer, and play a significant role in the initiation, progression and metastasis. Furthermore, their vital involvement in the therapeutic resistance of cancer has also been established. Hence, there has been enormous interest worldwide in investigating the roles of miRNAs in pancreatic cancer pathogenesis and exploiting their utility for clinical benefit. In this review, we summarize current knowledge on the role of miRNAs in pancreatic cancer and discuss their potential use as diagnostic and prognostic biomarkers, and as novel targets for development of effective therapeutic strategies.

Expression of microRNA-218 in human pancreatic ductal adenocarcinoma and its correlation with tumor progression and patient survival

BACKGROUND

Our aim was to analyze clinicopathologic and prognostic values of microRNA (miR)-218 in pancreatic ductal adenocarcinima (PDAC).

METHODS

TaqMan quantitative RT-PCR was used to determine the expression of miR-218 in human PDAC cells and tissue samples. The association of miR-218 expression with clinicopathologic variables was analyzed. Kaplan-Meier survival analysis was performed to analyze the association of miR-218 expression with recurrence-free survival or overall survival of patients. Univariate and multivariate Cox regression analyses were performed.

RESULTS

The relative level of miR-218 in PDAC cells was significantly lower than that in normal human pancreatic duct epithelial cell line. Also, the mean level of miR-218 in PDAC tissues was significantly lower than that in normal pancreatic tissues. Statistical analyses indicated that low miR-218 expression was closely associated with poor tumor differentiation, advanced tumor stage, higher incidence of lymph node metastasis, and tumor recurrence. Kaplan-Meier survival analyses showed that patients with low miR-218 expression had lower recurrence-free and overall survival than those with high miR-218 expression. Univariate and multivariate Cox regression analyses showed that miR-218 might be an independent prognostic factor.

CONCLUSION

Reduced miR-218 in PDAC tissues was correlated with tumor progression, and might be an independent poor prognostic factor for patients.

Large oncosomes mediate intercellular transfer of functional microRNA

Prostate cancer cells release atypically large extracellular vesicles (EVs), termed large oncosomes, which may play a role in the tumor microenvironment by transporting bioactive molecules across tissue spaces and through the blood stream. In this study, we applied a novel method for selective isolation of large oncosomes applicable to human platelet-poor plasma, where the presence of caveolin-1-positive large oncosomes identified patients with metastatic disease. This procedure was also used to validate results of a miRNA array performed on heterogeneous populations of EVs isolated from tumorigenic RWPE-2 prostate cells and from isogenic non-tumorigenic RWPE-1 cells. The results showed that distinct classes of miRNAs are expressed at higher levels in EVs derived from the tumorigenic cells in comparison to their non-tumorigenic counterpart. Large oncosomes enhanced migration of cancer-associated fibroblasts (CAFs), an effect that was increased by miR-1227, a miRNA abundant in large oncosomes produced by RWPE-2 cells. Our findings suggest that large oncosomes in the circulation report metastatic disease in patients with prostate cancer, and that this class of EV harbors functional molecules that may play a role in conditioning the tumor microenvironment.

Endoplasmic reticulum stress signaling: the microRNA connection

The endoplasmic reticulum (ER)-induced unfolded protein response (ERUPR) is an adaptive mechanism that is activated upon accumulation of misfolded proteins in the ER and aims at restoring ER homeostasis. The ERUPR is transduced by three major ER-resident stress sensors, namely PKR-like endoplasmic reticulum kinase (PERK), activating transcription factor 6 (ATF6), and inositol requiring enzyme 1 (IRE1). Activation of these ER stress sensors leads to transcriptional reprogramming of the cells. Recently, microRNAs (miRNAs), small noncoding RNAs that generally repress gene expression, have emerged as key regulators of ER homeostasis and important players in ERUPR-dependent signaling. Moreover, the miRNAs biogenesis machinery appears to also be regulated upon ER stress. Herein we extensively review the relationships existing between “canonical” ERUPR signaling, control of ER homeostasis, and miRNAs. We reveal an intricate signaling network that might confer specificity and selectivity to the ERUPR in tissue- or stress-dependent fashion. We discuss these issues in the context of the physiological and pathophysiological roles of ERUPR signaling.