Identification of microRNA-21 as a biomarker for chemoresistance and clinical outcome following adjuvant therapy in resectable pancreatic cancer

MiR-21 improves invasion and migration of drug-resistant lung adenocarcinoma cancer cell and transformation of EMT through targeting HBP1

This study was aimed at the investigation of the effects of miR-21 on drug resistance, invasion, migration, and epithelial-mesenchymal transition (EMT) of lung adenocarcinoma cells and the related molecular mechanisms. Cell viability of A549 cell line was measured by MTT assay. Wound healing assay and transwell assay were, respectively, employed to examine cell migration and invasion abilities. The cells were transfected with miR-21 mimic or inhibitor using Lipofectamine 3000. The target relationship between miR-21 and HBP1 was confirmed by luciferase reporter gene assay. Western blot and qRT-PCR were used to examine the expression of HBP1 and EMT-related molecules. Compared with A549 cells, drug resistance of A549/PTX cells and A549/DDP cells were obviously stronger. A549/PTX cells and A549/DDP cells had stronger ability of migration and invasion compared with parental A549 cells. Meanwhile, EMT of A549/PTX and A549/DDP was significantly higher than that of A549 cells. MiR-21 promoted migration, invasion, and EMT of human lung adenocarcinoma cancer cells. Our experiment also verified the target relationship between miR-21 and HBP1. MiR-21 may affect migration and invasion ability of drug-resistant lung adenocarcinoma cells by targeting HBP1, therefore modulating EMT.

microRNA based prognostic biomarkers in pancreatic Cancer

Despite tremendous research efforts focused on diagnosis and treatment, pancreatic ductal adenocarcinoma remains the third leading cause of cancer-related death in the United States, with a 5-year overall survival rate of less than 5%. Although resistance is rather complex, emerging evidence has demonstrated that epigenetic alterations (e.g. miRNA) have important roles in PDAC progression as well as resistance to therapy. Certain miRNAs have been identified as potential prognostic biomarkers in PDAC. In this review, we summarize the recent developments in miRNA research related to PDAC therapeutic resistance mechanisms and the potential of miRNAs as prognostic biomarkers for future clinical management of PDAC.

Urtica dioica extract suppresses miR-21 and metastasis-related genes in breast cancer

BACKGROUND

Breast cancer has a high prevalence among women worldwide. Tumor invasion and metastasis still remains an open issue that causes most of the therapeutic failures and remains the prime cause of patient mortality. Hence, there is an unmet need to develop the most effective therapeutic approach with the lowest side effects and highest cytotoxicity that will effectively arrest or eradicate metastasis.

METHODS

An MTT assay and scratch test were used to assess the cytotoxicity and migration effects of Urtica dioica on the breast cancer cells. The QRT-PCR was used to study the expression levels of miR-21, MMP1, MMP9, MMP13, CXCR4, vimentin, and E-cadherin.

RESULTS

The results of gene expression in tumoral groups confirmed the overexpression of miR-21, MMP1, MMP9, MMP13, vimentin, and CXCR4, and the lower expression of E-cadherin compared to control groups (P<0.05). Moreover, the results of the MTT assay show that Urtica dioica significantly inhibited breast cancer cell proliferation. Moreover, findings from the scratch assay exhibited the inhibitory effects of Urtica dioica on the migration of breast cancer cell lines.

CONCLUSION

Urtica dioica extract could inhibit cancer cell migration by regulating miR-21, MMP1, MMP9, MMP13, vimentin, CXCR4, and E-Cadherin. Moreover, our findings demonstrated that the extract could decrease miR-21 expression, which substantially lessens the overexpressed MMP1, MMP9, MMP13, vimentin, and CXCR4 and increases E-cadherin in the tumoral group.

Long noncoding RNA MALAT1 knockdown reverses chemoresistance to temozolomide via promoting microRNA-101 in glioblastoma

Glioblastoma (GBM) is the most common and lethal tumor of the central nervous system with highly infiltrative and resistant to chemotherapy. Temozolomide (TMZ) is widely used as the first-line treatment for the therapy of GBM. However, a considerable percentage inherent or acquired resistance in GBM accounts for many treatment failures of the TMZ chemotherapy. Therefore, a deeper understanding of the molecular characteristics underlying TMZ resistance and the identification of novel therapeutic target is urgent. Here, we show that MALAT1 was significantly upregulated in TMZ-resistant GBM cells. On the other hand, MALAT1 knockdown reduces TMZ resistance of GBM cells both in vitro and in vivo by inhibiting cell proliferation and promoting apoptosis. We also show that miR-101 overexpression reduced TMZ resistance of GBM cells and played an antagonistic role compared with MALAT1. Importantly, we demonstrate that MALAT1 promoted the chemoresistance through suppressing miR-101 signaling pathway via directly binding it in GBM cells. In conclusion, our study indicates that knockdown of MALAT1 reverses chemoresistance to TMZ via promoting miR-101 regulatory network in GBM and thus offers a novel prognostic marker and potential target for GBM TMZ-based chemotherapy.

Evaluation of several methodological challenges in circulating miRNA qPCR studies in patients with head and neck cancer

Circulating microRNAs (ci-miRNAs) in blood have emerged as promising diagnostic, prognostic and predictive biomarkers in cancer. Many clinical studies currently incorporate studies that assess ci-miRNAs. Validation of the clinical significance of candidate biomarker miRNAs has proven to be difficult, potentially resulting from vast discrepancies in the detection methodology as well as biological variability. In the current study, the influence of several methodological factors on ci-miRNA detection was evaluated as well as short-term biological variability in patients with head and neck cancer. RNA was isolated from 124 serum and plasma samples originating from patients with head and neck cancer and healthy volunteers. The miRNA levels were measured using RT-qPCR and the influence of pre-analytical factors, different normalization strategies and temporal reproducibility was assessed. RNA carriers improved ci-miRNA detection in serum and plasma specimens. A prolonged pre-processing time correlated with an increased hemolytic index in serum samples only. Hemolysis differentially affected the detection of individual miRNAs. Optimal normalization was achieved using the averaged detection values of spike-in cel-miR-39-3p and endogenous miR-16-5p. Comparing biological replicates from patients with head and neck cancer, the intra-individual miRNA levels were relatively stable (average interval 7 days). Differences in the ci-miRNA detection methodology and limitations of currently used technologies can greatly affect the results and may explain inconsistent outcomes between studies. Prior to the implementation of ci-miRNAs as useful clinical biomarkers, further advances in the standardization of the detection methodology and reduction of technical variability are needed.

MicroRNA-21 contributes to the discrimination of chemoresistance in metastatic gastric cancer

BACKGROUND

Multidrug resistance in gastric cancer greatly impedes the efficacy of chemotherapy.

OBJECTIVE

To explore the efficacy of microRNA-21 (mir-21) in distinguishing metastatic gastric cancer (MGC) with chemoresistance.

METHODS

From April 2012 to May 2015, 92 MGC patients were enrolled. Cisplatin and fluorouracil-based systemic chemotherapy was given, and patients' characteristics and follow-up data were collected. In addition, miR-21 expression was determined in tumor tissue and plasma.

RESULTS

Sixty-seven patients responded to chemotherapy, and chemotherapy resistance was observed in 25 patients. miR-21 expression in tumor tissue and plasma was significantly elevated in the chemotherapy-resistant group (CRG) compared to the chemotherapy-sensitive group (CSG) (p< 0.001). miR-21 expression in tissue was associated with tumor differentiation (p= 0.042), and plasma miR-21 was correlated with gender (p= 0.016), tumor differentiation (p= 0.003), and number of metastatic sites (p< 0.001). Receiver operating characteristic (ROC) analysis indicated that miR-21 in tissue yielded an area under the ROC curve (AUC) of 0.830 (95%CI: 0.737-0.900, sensitivity: 88.0%, specificity: 68.7%) in distinguishing CRG from CSG; and plasma miR-21 yielded an AUC of 0.759 (95%CI: 0.658-0.842, sensitivity: 52.0%, specificity: 88.1%) in distinguishing CRG form CSG. Log-rank test and Cox proportional hazard regression analysis indicated that patients with higher miR-21 expression in tissue and plasma experienced shorter overall survival (P< 0.001).

CONCLUSION

miR-21 could serve as a potential biomarker to identify MGC with chemoresistance.

Advanced EUS Guided Tissue Acquisition Methods for Pancreatic Cancer

Pancreas cancer is a lethal cancer as the majority patients are diagnosed at an advanced incurable stage. Despite improvements in diagnostic modalities and management strategies, including surgery and chemotherapies, the outcome of pancreas cancer remains poor. Endoscopic ultrasound (EUS) is an important imaging tool for pancreas cancer. For decades, resected pancreas cancer and other cancer specimens have been used to identify tissue biomarkers or genomics for precision therapy; however, only 20% of patients undergo surgery, and thus, this framework is not useful for unresectable pancreas cancer. With advancements in needle technologies, tumor specimens can be obtained at the time of tissue diagnosis. Tumor tissue can be used for development of personalized cancer treatment, such as performing whole exome sequencing and global genomic profiling of pancreas cancer, development of tissue biomarkers, and targeted mutational assays for precise chemotherapy treatment. In this review, we discuss the recent advances in tissue acquisition of pancreas cancer.

miR-1266 Contributes to Pancreatic Cancer Progression and Chemoresistance by the STAT3 and NF-κB Signaling Pathways

Pancreatic cancer is characterized by chemoresistance after several cycles of chemotherapy, which is a major issue responsible for treatment failure of pancreatic cancer. Therefore, it is necessary to explore the specific mechanism underlying chemotherapeutic resistance to overcome this issue. Here we report that miR-1266 is dramatically elevated and correlates with poor survival and chemotherapy response in pancreatic cancer patients. Upregulation of miR-1266 enhanced the chemoresistance of pancreatic cancer cells to gemcitabine (GEM) in vitro and in vivo; conversely, inhibition of miR-1266 yielded the opposite effect. Importantly, silencing of miR-1266 restored the sensitivity of pancreatic cancer cells to GEM in a dose-dependent manner in vivo. Furthermore, our results demonstrate that miR-1266 promotes resistance of pancreatic cancer cells to GEM by targeting multiple negative regulators of the STAT3 and NF-κB pathways, including SOCS3, PTPN11, ITCH, and TNIP1, leading to constitutive activation of STAT3 and NF-κB signaling. Thus, our findings clarify a novel mechanism by which miR-1266 induces chemotherapeutic resistance in pancreatic cancer, indicating that miR-1266 may be used as chemotherapeutic response indicator. Antagomir-1266 as a chemotherapeutic sensitizer, in combination with GEM, may serve as a rational regimen in the treatment of chemotherapy-resistant pancreatic cancer.

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.

Downregulation of miR-874-3p promotes chemotherapeutic resistance in colorectal cancer via inactivation of the Hippo signaling pathway

Overcoming resistance to chemotherapy is an arduous challenge in the treatment of colorectal cancer (CRC), particularly since the underlying molecular mechanisms remain obscure. In the present study, we reported that miR-874-3p was markedly downregulated in CRC tissues compared with that in adjacent normal colorectal epithelial tissues. Upregulation of miR-874-3p attenuated the chemoresistance of CRC cells to 5-fluorouracil (5-FU) in vitro and in vivo. Conversely, inhibition of miR-874-3p yielded an opposite effect. Furthermore, our results demonstrated that miR-874-3p directly inhibited the expression of transcriptional co-activators YAP and TAZ of the Hippo signaling pathway, resulting in the inactivation of the TEAD transcription. Thus, our findings clarify a novel mechanism by which miR-874-3p restores chemotherapeutic sensitivity of CRC to 5-FU, indicating that offering miR-874-3p mimics in combination with 5-FU may serve as a new therapeutic strategy to circumvent the chemoresistance in CRC.

MiR-608 regulating the expression of ribonucleotide reductase M1 and cytidine deaminase is repressed through induced gemcitabine chemoresistance in pancreatic cancer cells

PURPOSE

Gemcitabine resistance is the main problem in pancreatic adenocarcinoma patients. Hence, we aimed to identify the correlation between expression of RRM1 and CDA as the resistance genes and their predicted targeting miR-608 in the resistant pancreatic cancer cell lines to gemcitabine.

METHODS

Dual luciferase assay was performed to determine whether both RRM1 and CDA are targeted by miR-608 in 293T and pancreatic cancer cell lines. AsPC-1 and MIA PaCa-2 cell lines became gradually resistant to gemcitabine by exposing to the increasing doses of gemcitabine. After RNA and miRNAs extraction and cDNA conversion, the expressions of RRM1, CDA and miR-608 in all cell lines were studied by quantitative PCR. Pre-miR-608 transfection to the cell lines was done by calcium phosphate method. MTT assay was performed for analyzing the chemo sensitivity of different cell lines to gemcitabine.

RESULTS

Luciferase assays showed that miR-608 targeted RRM1 and CDA genes in 293T, AsPC-1 and MIA PaCa-2 cell lines. Compared to parental cell line, resistant MIA PaCa-2 and AsPC-1 cells demonstrated increased expression of RRM1 and CDA. On the other hand the expression of miR-608 in resistant MIA PaCa-2 and AsPC-1 cells was lower than parental cells. Furthermore, transfection of MIA PaCa-2 and AsPC-1 cells by miR-608 lead to decreased expression of RRM1 and CDA and lowered viability of the cells in comparison with scrambled microRNA transfected cells.

CONCLUSION

During resistance induction in pancreatic cancer cells, miR-608 which is targeting RRM1 and CDA is downregulated which leads to upregulation of these genes.

microRNAs Make the Call in Cancer Personalized Medicine

Since their discovery and the advent of RNA interference, microRNAs have drawn enormous attention because of their ubiquitous involvement in cellular pathways from life to death, from metabolism to communication. It is also widely accepted that they possess an undeniable role in cancer both as tumor suppressors and tumor promoters modulating cell proliferation and migration, epithelial-mesenchymal transition and tumor cell invasion and metastasis. Moreover, microRNAs can even affect the tumor surrounding environment influencing angiogenesis and immune system activation and recruitment. The tight association of microRNAs with several cancer-related processes makes them undoubtedly connected to the effect of specific cancer drugs inducing either resistance or sensitization. In this context, personalized medicine through microRNAs arose recently with the discovery of single nucleotide polymorphisms in the target binding sites, in the sequence of the microRNA itself or in microRNA biogenesis related genes, increasing risk, susceptibility and progression of multiple types of cancer in different sets of the population. The depicted scenario implies that the overall variation displayed by these small non-coding RNAs have an impact on patient-specific pharmacokinetics and pharmacodynamics of cancer drugs, pushing on a rising need of personalized treatment. Indeed, microRNAs from either tissues or liquid biopsies are also extensively studied as valuable biomarkers for disease early recognition, progression and prognosis. Despite microRNAs being intensively studied in recent years, a comprehensive review describing these topics all in one is missing. Here we report an up-to-date and critical summary of microRNAs as tools for better understanding personalized cancer biogenesis, evolution, diagnosis and treatment.

Notch and its oncogenic activity in human malignancies

BACKGROUND

Increasing evidence has demonstrated that Notch signaling is deregulated in human hematological malignancies and solid tumors. This signaling has a protumorigenic effect but may also act as a tumor suppressor. How induction of a single pathway gives rise to the opposite effects in different cell types is still unknown.

METHODS

This review article includes available data from peer-reviewed publications associated with the role of Notch signaling during cancer pathogenesis.

RESULTS

Numerous reports have indicated that alterations in Notch signaling and its oncogenic activity were originally associated with the pathogenesis of T‑cell acute lymphoblastic leukemia/lymphoma (T-ALL), an aggressive hematologic tumor affecting children and adolescents. The possibility that Notch could play a significant role in human breast cancer development comes from studies on mouse mammary tumor virus-induced cancer. Numerous findings over the past several years have indicated that alterations in Notch signaling are also responsible for ovarian cancer development. Mention should also be made of the connection between expression of Notch 3 and increased resistance to chemotherapy, which remains a major obstacle to successful treatment. Notch as an oncogenic factor is also involved in the development of colon cancer, lung carcinoma and Kaposi's sarcoma.

CONCLUSION

Notch is a binary cell fate determinant and its overexpression has been described as oncogenic in a wide array of human malignancies. This finding led to interest in therapeutically targeting this pathway, especially by the use of gamma-secretase inhibitors (GSIs) blocking the cleavage of Notch receptors at the cell membrane by the inhibition of Notch intracellular domain (NICD) releasing. Preclinical cancer models have revealed that GSIs suppress the growth of cancers such as pancreatic, breast and lung cancer.

Future role of endoscopic ultrasound in personalized management of pancreatic cancer

Pancreatic ductal adenocarcinoma (PDAC) is aggressive and lethal with the majority of cases presenting with advanced unresectable disease due to delayed diagnosis. Despite improvement in surgery, chemotherapies, and intensive care medicine, the outcome of PDAC remains poor, which may relate to the tumor biology. Recent data suggest that PDAC is a "systemic cancer" with complex molecular or genomics derangement with marked heterogeneity. The ability to characterize the PDAC better by detailed evaluation of tissue biomarkers or genomics allows for improved prediction of prognosis and stratification of treatment, a concept known as "personalized cancer therapy." Using tissue from resected PDAC specimens has several weaknesses and is only possible in 20% of patients with PDAC. Endoscopic ultrasound (EUS)-guided biopsy overcomes these weaknesses, and with recent advancements in needle technology, tissue can be obtained for personalized cancer therapy for all patients with PDAC. This review aims to outline our current understanding of the molecular biology of PDAC specifically focusing on how EUS-guided biopsy may play a fundamental role in tissue acquisition, allowing for assessment and stratify therapy according to the individual cancer biology as we move toward the era of precision medicine.

MicroRNA-21 as a prognostic biomarker in patients with pancreatic cancer - A systematic review and meta-analysis

OBJECTIVES

The aim of this systematic review and meta-analysis is to summarize the current knowledge regarding microRNA-21 and to evaluate its prognostic impact in patients with pancreatic cancer.

METHODS

We conducted an electronic literature search to identify all published studies in PubMed/MEDLINE, Scopus and Google Scholar databases from 2000 until August 2016.

RESULTS

A total of 17 studies involving 1471 patients met the inclusion criteria for the quantitative synthesis. The microRNA-21 upregulation was significantly associated with poorer overall survival, disease-free survival, and progression-free survival. The subgroup analysis revealed that microRNA-21 overexpression has a significant higher prognostic value for patients who receive adjuvant chemotherapy. Increased microRNA-21 was associated with a statistically significant higher rate of metastatic lymph nodes and poorly differentiated tumors.

CONCLUSIONS

MicroRNA-21 upregulation in pancreatic cancer is associated with a significantly poorer overall survival, disease-free survival, and progression-free survival. MicroRNA-21 may be a useful prognostic biomarker, allowing stratification for chemotherapy administration, and being a component of precision medicine in patients with pancreatic cancer.

miRNA profiling for diagnosis, prognosis and stratification of cancer treatment in cholangiocarcinoma

Cholangiocarcinoma (CCA) is a lethal malignancy originating from the biliary tract epithelium. Most patients are diagnosed at an advanced stage. Even after resection with curative intent, prognosis remains poor. Previous studies have reported the evolving role of miRNAs as novel biomarkers in cancer diagnosis, prognostication and chemotherapy response. Various miRNAs, such as miR-21, miR-26, miR-122 and miR-150, have been identified as possible blood-based biomarkers for noninvasive diagnosis of CCA. Moreover, epithelial-mesenchymal transition (EMT)- and angiogenesis-associated miRNAs have been implicated in tumor cell dissemination and are able to determine clinical outcome. In fact, miRNAs involved in cell survival might even determine chemotherapy response. This review provides an overview of known miRNAs as CCA-specific biomarkers.

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.

NO• and Pancreatic Cancer: A Complex Interaction with Therapeutic Potential

SIGNIFICANCE

Pancreatic tumors express high level of nitric oxide synthases (NOSs) in particular inducible (iNOS/NOS2) and endothelial (eNOS/NOS3) forms. However, the role of nitric oxide (NO^•) in the development and progression of pancreatic cancer is not clearly defined. Delineating the NO^•-induced signaling in pancreatic cancer and its potential contribution in disease aggressiveness may provide therapeutic targets to improve survival in this lethal malignancy. Recent Advances: An increased expression of NOS2/iNOS in tumors is associated with poorer survival in early stage resected patients with pancreatic ductal adenocarcinoma (PDAC). Furthermore, genetic deletion of NOS2 enhanced survival in mice with autochthonous PDAC. Additionally, targeting NOS3/eNOS reduced the abundance of precursor lesions in mice, which trended toward improved survival.

CRITICAL ISSUES

The extremely poor prognosis in pancreatic cancer is due to the late diagnosis and lack of effective therapy in advanced disease. One of the most critical issues is to decipher the underlying mechanism of disease aggressiveness and therapeutic resistance for identifying potential therapeutic target and effective treatment. Given the evidence of a strong association between inflammation and pancreatic cancer and clinical evidence, which suggests an association between NOS2 and disease aggressiveness, it is critical to define the role of NO^• signaling in this lethal malignancy.

FUTURE DIRECTIONS

Recent preclinical and clinical evidences indicate a potential therapeutic significance of targeting NO^• signaling in pancreatic cancer. With the emergence of new preclinical models, including the patient-derived organoids, further preclinical evaluation using clinically tested NOS inhibitors is needed for designing future clinical investigation. Antioxid. Redox Signal. 26, 1000-1008.

Effects of microRNA-183 on epithelial-mesenchymal transition, proliferation, migration, invasion and apoptosis in human pancreatic cancer SW1900 cells by targeting MTA1

OBJECTIVE

This study aims to explore effects of miR-183 on epithelial-mesenchymal transition (EMT) and invasion by targeting MTA1 in human pancreatic cancer (PC) cells.

METHODS

Totally, 108 PC patients admitted in Wenzhou Central Hospital and Wenzhou People's Hospital, The Dingli Clinical Institute of Wenzhou Medical University from March 2010 to March 2014 were enrolled. qRT-PCR and immunohistochemistry were applied to examine expression of MTA1 mRNA and protein. Samples were divided into 6 groups: blank, NC, miR-183 mimics, miR-183 inhibitors, MTA1-siRNA and miR-183 inhibitors +MTA1-siRNA groups. CCK8 method was employed for determining cell proliferation rate, flow cytometry for cell apoptosis rate, scratch test for cell migration and Transwell assay for cell invasion. qRT-PCR and Western blotting were used to determine expression of MTA1, E-cadherin and Vimentin mRNA and protein.

RESULTS

Positive expression rate of MTA1 was upregulated in PC tissues, and expression of miR-183 and MTA1 was associated with differentiation, migration, tumor size, TNM. The miR-183 mimics and MTA1-siRNA groups showed a decrease in proliferation, migration and invasion, whereas increased apoptosis, in comparison with blank and NC groups, as expression of MTA1 and Vimentin mRNA and protein were reduced, expression of E-cadherin mRNA and protein was elevated. Compared to blank and NC groups, the miR-183 inhibitors group exhibited enhanced proliferation, migration and invasion and inhibited apoptosis; increased expressions of MTA1 and Vimentin mRNA and protein and decreased expressions of E-cadherin mRNA and protein.

CONCLUSION

Our study supported that miR-183 could repress EMT and invasion of human PC cells through inhibition of MTA1 expression.

miRNAs: micro-managers of anticancer combination therapies

Angiogenesis is one of the hallmarks of cancer progression and as such has been considered a target of therapeutic interest. However, single targeted agents have not fully lived up to the initial promise of anti-angiogenic therapy. Therefore, it has been suggested that combining therapies and agents will be the way forward in the oncology field. In recent years, microRNAs (miRNAs) have received considerable attention as drivers of tumor development and progression, either acting as tumor suppressors or as oncogenes (so-called oncomiRs), as well as in the process of tumor angiogenesis (angiomiRs). Not only from a functional, but also from a therapeutic view, miRNAs are attractive tools. Thus far, several mimics and antagonists of miRNAs have entered clinical development. Here, we review the provenance and promise of miRNAs as targets as well as therapeutics to contribute to anti-angiogenesis-based (combination) treatment of cancer.

Impact of BRAF kinase inhibitors on the miRNomes and transcriptomes of melanoma cells

BACKGROUND

Melanoma is an aggressive skin cancer with increasing incidence worldwide. The development of BRAF kinase inhibitors as targeted treatments for patients with BRAF-mutant tumours contributed profoundly to an improved overall survival of patients with metastatic melanoma. Despite these promising results, the emergence of rapid resistance to targeted therapy remains a serious clinical issue.

METHODS

To investigate the impact of BRAF inhibitors on miRNomes and transcriptomes, we used in vitro melanoma models consisting of BRAF inhibitor-sensitive and -resistant cell lines generated in our laboratory. Subsequently, microarray analyses were performed followed by RT-qPCR validations.

RESULTS

Regarding miRNome and transcriptome changes, the long-term effects of BRAF inhibition differed in a cell line-specific manner with the two different BRAF inhibitors inducing comparable responses in three melanoma cell lines. Despite this heterogeneity, several miRNAs (e.g. miR-92a-1-5p, miR-708-5p) and genes (e.g. DOK5, PCSK2) were distinctly differentially expressed in drug-resistant versus -sensitive cell lines. Analyses of coexpressed miRNAs, as well as inversely correlated miRNA-mRNA pairs, revealed a low MITF/AXL ratio in two drug-resistant cell lines that might be regulated by miRNAs.

CONCLUSION

Several genes and miRNAs were differentially regulated in the drug-resistant and -sensitive cell lines and might be considered as prognostic and/or diagnostic resistance biomarkers in melanoma drug resistance.

GENERAL SIGNIFICANCE

Thus far, only little information is available on the significance and role of miRNAs with respect to kinase inhibitor treatments and emergence of drug resistance. In this study, promising miRNAs and genes were identified and associated to BRAF inhibitor-mediated resistance in melanoma. This article is part of a Special Issue entitled "Biochemistry of Synthetic Biology - Recent Developments" Guest Editor: Dr. Ilka Heinemann and Dr. Patrick O'Donoghue.

Insights into the involvement of noncoding RNAs in 5-fluorouracil drug resistance

5-Fluorouracil is a classic chemotherapeutic drug that is widely used to treat various cancers. However, patients often exhibit primary or acquired drug resistance during treatment with 5-fluorouracil chemotherapy. 5-Fluorouracil resistance is a multifactorial event that involves abnormal enzyme metabolism, transport deregulation, cell cycle disorders, apoptosis resistance, and mismatch repair deficiency. Despite advancements in bioresearch technologies in the past several decades, the molecular mechanisms of 5-fluorouracil resistance have not been completely clarified. Recently, microarray analyses have shown that noncoding RNAs (i.e. microRNAs and long noncoding RNAs) play a vital role in 5-fluorouracil resistance in multiple cancer cell lines. These noncoding RNAs can function as oncogenes or tumor suppressors, contributing to 5-fluorouracil drug resistance. In this review, we discuss the effects of microRNAs on 5-fluorouracil sensitivity via targeting of metabolic enzymes, the cell cycle, apoptosis, autophagy, the epithelial–mesenchymal transition, and cancer stem cells. In particular, we focus on summarizing current knowledge on the molecular mechanisms through which long noncoding RNAs mediate 5-fluorouracil drug resistance. Moreover, we describe the specific microRNAs that may function as markers for prediction of chemotherapeutic response to 5-fluorouracil. This review will help to improve the current understanding of how to reverse 5-fluorouracil resistance and may facilitate the establishment of new strategies for alleviating drug resistance in the future.

MiR-143 Targeting TAK1 Attenuates Pancreatic Ductal Adenocarcinoma Progression via MAPK and NF-κB Pathway In Vitro

BACKGROUND

Transforming growth factor (TGF)-β-activated kinase 1 (TAK1) is one of the major regulators of inflammation-induced cancer cell growth and progression. MiR-143 dysregulation is a common event in a variety of human diseases including pancreatic ductal adenocarcinoma (PDA).

AIMS

To identify the interaction between TAK1 and miR-143 in PDA.

METHODS

Data mining of TAK1 expression in PDA patient gene profiling was conducted. QRT-PCR and western blot were performed to detect the expression of TAK1 in PDA tissues and cell lines. Ectopic miR-143 and TAK1 were introduced to PDA cells. Cell growth, apoptosis and migration were examined. Xenograft models were used to examine the function of TAK1 in vivo. Western blot and luciferase assay were carried out to investigate the direct target of miR-143.

RESULTS

PDA patient gene profiling data (GSE15471 and GSE16515) showed that TAK1 mRNA was aberrantly up-regulated in PDA tissues. TAK1 protein levels were overexpressed in PDA tissues and cell lines. Overexpression of TAK1 was strongly associated with positive lymph node metastasis. Inhibition of TAK1 suppressed cell growth, migration, and induced cell apoptosis in vitro and in vivo. Further studies demonstrated that TAK1 was a direct target gene of miR-143. MiR-143 also inhibited PDA cells proliferation and migration, induced apoptosis and G₁/S arrest. Moreover, TAK1 depletion inactivated MAPK and NF-κB pathway, mimicking the function of miR-143.

CONCLUSIONS

The study highlights that miR-143 acts as a tumor suppressor in PDA through directly targeting TAK1, and their functional regulation may provide potential therapeutic strategies in clinics.

Enhancing Drug Efficacy and Therapeutic Index through Cheminformatics-Based Selection of Small Molecule Binary Weapons That Improve Transporter-Mediated Targeting: A Cytotoxicity System Based on Gemcitabine

The transport of drug molecules is mainly determined by the distribution of influx and efflux transporters for which they are substrates. To enable tissue targeting, we sought to develop the idea that we might affect the transporter-mediated disposition of small-molecule drugs via the addition of a second small molecule that of itself had no inhibitory pharmacological effect but that influenced the expression of transporters for the primary drug. We refer to this as a “binary weapon” strategy. The experimental system tested the ability of a molecule that on its own had no cytotoxic effect to increase the toxicity of the nucleoside analog gemcitabine to Panc1 pancreatic cancer cells. An initial phenotypic screen of a 500-member polar drug (fragment) library yielded three “hits.” The structures of 20 of the other 2,000 members of this library suite had a Tanimoto similarity greater than 0.7 to those of the initial hits, and each was itself a hit (the cheminformatics thus providing for a massive enrichment). We chose the top six representatives for further study. They fell into three clusters whose members bore reasonable structural similarities to each other (two were in fact isomers), lending strength to the self-consistency of both our conceptual and experimental strategies. Existing literature had suggested that indole-3-carbinol might play a similar role to that of our fragments, but in our hands it was without effect; nor was it structurally similar to any of our hits. As there was no evidence that the fragments could affect toxicity directly, we looked for effects on transporter transcript levels. In our hands, only the ENT1-3 uptake and ABCC2,3,4,5, and 10 efflux transporters displayed measurable transcripts in Panc1 cultures, along with a ribonucleoside reductase RRM1 known to affect gemcitabine toxicity. Very strikingly, the addition of gemcitabine alone increased the expression of the transcript for ABCC2 (MRP2) by more than 12-fold, and that of RRM1 by more than fourfold, and each of the fragment “hits” served to reverse this. However, an inhibitor of ABCC2 was without significant effect, implying that RRM1 was possibly the more significant player. These effects were somewhat selective for Panc cells. It seems, therefore, that while the effects we measured were here mediated more by efflux than influx transporters, and potentially by other means, the binary weapon idea is hereby fully confirmed: it is indeed possible to find molecules that manipulate the expression of transporters that are involved in the bioactivity of a pharmaceutical drug. This opens up an entirely new area, that of chemical genomics-based drug targeting.

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

Background

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

Methods

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

Results

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

Conclusion

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

Electronic supplementary material

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

RNA Biomarkers: Frontier of Precision Medicine for Cancer

As an essential part of central dogma, RNA delivers genetic and regulatory information and reflects cellular states. Based on high-throughput sequencing technologies, cumulating data show that various RNA molecules are able to serve as biomarkers for the diagnosis and prognosis of various diseases, for instance, cancer. In particular, detectable in various bio-fluids, such as serum, saliva and urine, extracellular RNAs (exRNAs) are emerging as non-invasive biomarkers for earlier cancer diagnosis, tumor progression monitor, and prediction of therapy response. In this review, we summarize the latest studies on various types of RNA biomarkers, especially extracellular RNAs, in cancer diagnosis and prognosis, and illustrate several well-known RNA biomarkers of clinical utility. In addition, we describe and discuss general procedures and issues in investigating exRNA biomarkers, and perspectives on utility of exRNAs in precision medicine.

Role of Host miRNA Hsa-miR-139-3p in HPV-16-Induced Carcinomas

Purpose: Human papillomavirus 16 (HPV-16) is an important risk factor in head and neck cancer (HNC). Studies suggest that miRNAs play an important role in cancer; however, their role in HPV-mediated oncogenesis remains largely unknown. We investigated the role of miRNAs with HPV-16 as putative target in HPV-16-mediated cancers.Experimental Design: Using in silico tools, we identified miRNAs with putative binding sequences on HPV-16 miRNAs. Hsa-miR-139-3p was identified as best candidate miRNA by luciferase reporter assay and was found to be significantly downregulated in HPV-16-positive tissues and cell lines. Overexpression/inhibition studies were performed to determine the role of miRNA in regulating oncogenic pathways.Results: Hsa-miR-139-3p was found to target high-risk HPV-16 oncogenic proteins and revive major tumor suppressor proteins (p53, p21, and p16). This resulted in inhibition of cell proliferation and cell migration, cell-cycle arrest at G₂-M phase and increased cell death of HPV-16-positive cells. Analysis of The Cancer Genome Atlas (TCGA) data showed decreased expression of Hsa-miR-139-3p in HPV-16-positive HNC and cervical cancer cases, and its higher expression correlated with better survival outcome in both cases. Increased DNA methylation of Hsa-miR-139-3p harboring gene PDE2A at its promoter/CpG islands was observed in HPV-16-positive tissues and cell lines, which further correlated with Hsa-miR-139-3p expression, suggesting its role in regulating Hsa-miR-139-3p expression. Furthermore, we observed an increased sensitization of Hsa-miR-139-3p overexpressed HPV-16-positive cells to chemotherapeutic drugs (cisplatin and 5-fluorouracil).Conclusions: HPV-16-mediated downregulation of Hsa-miR-139-3p may promote oncogenesis in HNC and cervical cancer. Clin Cancer Res; 23(14); 3884-95. ©2017 AACR.

Pancreatic cancer: Stroma and its current and emerging targeted therapies

Pancreatic ductal adenocarcinoma (PDAC) is one of the most lethal human malignancies with a 5-year survival rate of 8%. Dense, fibrotic stroma associated with pancreatic tumors is a major obstacle for drug delivery to the tumor bed and plays a crucial role in pancreatic cancer progression. Targeting stroma is considered as a potential therapeutic strategy to improve anti-cancer drug efficacy and patient survival. Although numerous stromal depletion therapies have reached the clinic, they add little to overall survival and are often associated with toxicity. Furthermore, increasing evidence suggests the anti-tumor properties of stroma. Its complete ablation enhanced tumor progression and reduced survival. Consequently, efforts are now focused on developing stromal-targeted therapies that normalize the reactive stroma and avoid the extremes: stromal abundance vs. complete depletion. In this review, we summarized the state of current and emerging anti-stromal targeted therapies, with major emphasis on the role of miRNAs in PDAC stroma and their potential use as novel therapeutic agents to modulate PDAC tumor-stromal interactions.

The Emerging Role of miRNAs and Their Clinical Implication in Biliary Tract Cancer

Biliary tract cancers are aggressive malignancies that include gallbladder cancer and tumors of intra- and extrahepatic ducts and have a poor prognosis. Surgical resection remains the main curative therapy. Nevertheless, numerous patients experience recurrence even after radical surgery. This scenario drives the research to identify biliary tract cancer biomarkers despite the limited progress that has been made. Recently, a large number of studies have demonstrated that deregulated expression of microRNAs is closely associated with cancer development and progression. In this review, we highlight the role and importance of microRNAs in biliary tract cancers with an emphasis on utilizing circulating microRNAs as potential biomarkers. Additionally, we report several single-nucleotide polymorphisms in microRNA genes that are associated with the susceptibility of biliary tract tumors.

Exosomes-mediate microRNAs transfer in breast cancer chemoresistance regulation

Breast cancer is the most common and fatal type of cancer in women worldwide due to the metastatic process and resistance to treatment. Despite advances in molecular knowledge, little is known regarding resistance to chemotherapy. One highlighted aspect is the DNA damage response (DDR) pathway that is activated upon genotoxic damage, controlling the cell cycle arrest or DNA repair activation. Recently, studies have showed that cancer stem cells (CSCs) could promote chemoresistance through DDR pathway. Furthermore, it is known that the epithelial-mesenchymal transition (EMT) can generate cells with CSCs characteristics and therefore regulate the chemoresistance process. The exosomes are microvesicles filled with RNAs, proteins and microRNAs (miRNAs) that can be released by many cell types, including tumor cells and CSCs. The exosomes content may be cell-to-cell transferable and it could control a wide range of pathways during tumor development and metastasis. A big challenge for modern medicine is to determine the reasons why patients do not respond to chemotherapy treatments and also guide the most appropriate therapy for each one. Considering that the CSCs are able to stimulate the formation of a more aggressive tumor phenotype with migration and metastasis ability, resistance to treatment and disease recurrence, as well as few studies capable to determine clearly the interaction of breast CSCs with its microenvironment, the present review summarize the possibility that exosomes-mediate miRNAs transfer and regulate chemoresistance in breast tumor cells and CSCs, to clarify the complexity of breast cancer progression and therapy.

Changes in microRNA (miRNA) expression during pancreatic cancer development and progression in a genetically engineered KrasG12D;Pdx1-Cre mouse (KC) model

Differential expression of microRNAs (miRNAs) has been demonstrated in various cancers, including pancreatic cancer (PC). Due to the lack of tissue samples from early-stages of PC, the stage-specific alteration of miRNAs during PC initiation and progression is largely unknown. In this study, we investigated the global miRNA expression profile and their processing machinery during PC progression using the Kras^G12D;Pdx1-Cre (KC) mouse model. At 25 weeks, the miRNA microarray analysis revealed significant downregulation of miR-150, miR-494, miR-138, miR-148a, miR-216a, and miR-217 and upregulation of miR-146b, miR-205, miR-31, miR-192, and miR-21 in KC mice compared to controls. Further, expression of miRNA biosynthetic machinery including Dicer, Exportin-5, TRKRA, and TARBP2 were downregulated, while DGCR8 and Ago2 were upregulated in KC mice. In addition, from 10 to 50 weeks of age, stage-specific expression profiling of miRNA in KC mice revealed downregulation of miR-216, miR-217, miR-100, miR-345, miR-141, miR-483-3p, miR-26b, miR-150, miR-195, Let-7b and Let-96 and upregulation of miR-21, miR-205, miR-146b, miR-34c, miR-1273, miR-223 and miR-195 compared to control mice. Interestingly, the differential expression of miRNA in mice also corroborated with the miRNA expression in human PC cell lines and tissue samples; ectopic expression of Let-7b in CD18/HPAF and Capan1 cells resulted in downregulation of KRAS and MSST1 expression. Overall, the present study aids an understanding of miRNA expression patterns during PC pathogenesis and helps to facilitate the identification of promising and novel early diagnostic/prognostic markers and therapeutic targets.

FOLFIRINOX and translational studies: Towards personalized therapy in pancreatic cancer

Pancreatic cancer is an extremely aggressive disease; although progress has been made in the last few years, the prognosis of these patients remains dismal. FOLFIRINOX is now considered a standard treatment in first-line setting, since it demonstrated an improved overall and progression-free survival vs gemcitabine alone. However, the enthusiasm over the benefit of this three-drug regimen is tempered by the associated increased toxicity profile, and many efforts have been made to improve the feasibility of this schedule. After a more recent phase III trial showing an improved outcome over gemcitabine, the combination of gemcitabine/nab-paclitaxel emerged as another standard first-line treatment. However, this treatment is also associated with more side effects. In addition, despite initial promising data on the predictive role of SPARC levels, recent studies showed that these levels are not associated with nab-paclitaxel efficacy. The choice to use this treatment over FOLFIRINOX is therefore a topic of debate, also because no validated biomarkers to guide FOLFIRINOX treatment are available. In the era of actionable mutations and target agents it would be desirable to identify molecular factors or biomarkers to predict response to therapy in order to maximize the efficacy of treatment and avoid useless toxic effects for non-responding patients. However, until today the milestone of treatment for pancreatic cancer remains chemotherapy combinations, without predictive or monitoring tools existing to optimize therapy. This review analyzes the state-of-the-art treatments, promises and limitations of targeted therapies, ongoing trials and future perspectives, including potential role of microRNAs as predictive biomarkers.

The potential diagnostic value of serum microRNA signature in patients with pancreatic cancer

Biomarkers for early diagnosis of patients with pancreatic cancer (PC) are needed. Our aim was to identify panels of miRNAs in serum in combination with CA 19-9 for use in the diagnosis of PC. Four hundred seventeen patients with PC were included prospectively from Denmark (n = 306) and Germany (n = 111). Controls included 59 patients with chronic pancreatitis (CP) and 248 healthy subjects (HS). MiRNAs were analyzed in pretreatment serum samples from 3 cohorts: discovery cohort (754 human miRNAs, TaqMan(®) Human MicroRNA assay, Applied Biosystem; PC n = 133, controls n = 72); training cohort (34 miRNAs, real-time qPCR using the Fluidigm BioMark™ System; PC n = 198, controls n = 184); validation cohort (13 miRNAs, real-time qPCR using the Fluidigm BioMark™ System; PC n = 86, controls n = 51). We found that 34 miRNAs in serum from PC patients in the discovery cohort were expressed differently than in controls. These miRNAs were tested in the training cohort, and four diagnostic panels were constructed that included 5 or 12 miRNAs (miR-16, -18a, -20a, -24, -25, -27a, -29c, -30a.5p, -191, -323.3p, -345 and -483.5p). Diagnostic accuracy of detecting PC in the training cohort was AUC (Index I 0.85; II 0.87; III 0.85; IV 0.95; CA 19-9 0.93); specificity (I 0.71; II 0.76; III 0.66; IV 0.90 (fixed sensitivity at 0.85); CA 19-9 0.93). Combining serum CA 19-9 and Index II best discriminated Stages I and II PC from HS [AUC 0.93 (0.90-0.96), sensitivity 0.77 (0.69-0.84), specificity 0.94 (0.90-0.96) and accuracy 0.88 (0.84-0.91)]. In conclusion, we identified four diagnostic panels based on 5 or 12 miRNAs in serum that could distinguish patients with PC from HS and CP.

The role of microRNAs in resistance to targeted treatments of non-small cell lung cancer

PURPOSE

Non-small cell lung cancer (NSCLC), accounting for the most of lung cancers, is usually diagnosed in advanced stage. Targeted treatments boost advanced NSCLC patients with certain mutations, but early drug resistance blocks the advantages of target medicine. MicroRNAs (miRNAs) are regarded as a cluster of small noncoding and posttranscriptionally negative regulating RNAs. We want to explore the role of miRNAs in resistance to targeted treatments of NSCLC to improve the prognosis.

METHODS

We reviewed recent studies about miRNAs and targeted treatment resistance in NSCLC and classified resistance into two types: EGFR-TKIs resistance and ALK-TKIs resistance.

RESULTS AND CONCLUSION

Recent studies indicate that miRNAs involve in drug resistance possession in positive and negative manners. Inhibiting expression of certain miRNAs that promote drug resistance and increasing expression of miRNAs that reverse drug resistance may illuminate novel prospect of adjuvant targeted treatments in NSCLC.

Evidence for the role of microRNA 374b in acquired cisplatin resistance in pancreatic cancer cells

Recent evidence has implicated microRNAs (miRNAs) as potentially significant players in the acquisition of cancer-drug resistance in pancreatic and other cancers. To evaluate the potential contribution of miRNAs in acquired resistance to cisplatin in pancreatic cancer, we compared levels of more than 2000 human miRNAs in a cisplatin-resistant cell line (BxPC3-R) derived from parental (BxPC3) cells by step-wise exposure to increasing concentrations of the drug over more than 20 passages. The acquired drug resistance was accompanied by significant changes in the expression of 57 miRNAs, of which 23 were downregulated and 34 were upregulated. Employing a hidden Markov model (HMM) algorithm, we identified downregulation of miR-374b as likely being directly involved in acquisition of the drug-resistant phenotype. Consistent with this prediction, ectopic overexpression of miR-374b in the resistant BxPC3-R cells restored cisplatin sensitivity to levels approaching those displayed by the BxPC3 parental cells. The results are consistent with a growing body of evidence implicating miRNAs in acquired cancer-drug resistance and with the potential therapeutic value of these small regulatory RNAs in blocking and/or reversing the process.

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.

Circulating MicroRNAs as Biomarkers in Biliary Tract Cancers

Biliary tract cancers (BTCs) are a group of highly aggressive malignant tumors with a poor prognosis. The current diagnosis is based mainly on imaging and intraoperative exploration due to brush cytology havinga low sensitivity and the standard markers, such as carcinoembryonic antigen (CEA) and carbohydrate 19-9 (CA19-9), not having enough sensitivity nor specificity to be used in a differential diagnosis and early stage detection. Thus, better non-invasive methods that can distinguish between normal and pathological tissue are needed. MicroRNAs (miRNAs) are small, single-stranded non-coding RNA molecules of ~20–22 nucleotides that regulate relevant physiological mechanisms and can also be involved in carcinogenesis. Recent studies have demonstrated that miRNAs are detectable in multiple body fluids, showing great stability, either free or trapped in circulating microvesicles, such as exosomes. miRNAs are ideal biomarkers that may be used in screening and prognosis in biliary tract cancers, aiding also in the clinical decisions at different stages of cancer treatment. This review highlights the progress in the analysis of circulating miRNAs in serum, plasma and bile as potential diagnostic and prognostic markers of BTCs.

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.

Prognostic value of microRNA-21 in pancreatic ductal adenocarcinoma: a meta-analysis

BACKGROUND

Recently, microRNA-21 (miR-21) has been reported to be associated with prognosis of pancreatic ductal adenocarcinoma (PDAC). The present studies aimed to evaluate the prognostic value of miR-21 for PDAC with meta-analysis.

METHODS

A systematic search in the PubMed and other databases was conducted to identify eligible studies. The pooled hazard ratios (HRs) with 95% confidence interval (CI) were calculated. The meta-analysis was conducted using the STATA 12.0 software.

RESULTS

A total of 12 articles (13 studies) which included 963 cases were selected for the meta-analysis. Elevated miR-21 expression was significantly predictive of poor overall survival (HR = 2.05, 95% CI 1.71-2.46, P < 0.001). In the subgroup analyses, similar results were observed in Asian (HR = 2.09, 95% CI 1.62-2.71, P < 0.001) and Caucasian (HR = 2.36, 95% CI 1.53-3.65, P < 0.001); in tissue sample (HR = 2.14, 95% CI 1.73-2.65, P < 0.001) and serum sample (HR = 1.84, 95% CI 1.30-2.60, P = 0.001); with quantitative real-time polymerase chain reaction assay method (HR = 2.31, 95% CI 1.86-2.86, P < 0.001); and in patients receiving adjuvant chemotherapy (HR = 2.37, 95% CI 1.88-3.00, P < 0.001). The association between miR-21 expression level and lymph node metastasis was statistically significant (OR = 1.45, 95% CI 1.02-2.06, P = 0.038). However, no significant relationship between miR-21 expression level and sex or vascular invasion or neural infiltration was observed (P > 0.05).

CONCLUSIONS

Our meta-analysis indicated that elevated miR-21 expression level can predict poor prognosis in patients with PDAC.

MicroRNA-21 induces 5-fluorouracil resistance in human pancreatic cancer cells by regulating PTEN and PDCD4

Pancreatic cancer patients are often resistant to chemotherapy treatment, which results in poor prognosis. The objective of this study was to delineate the mechanism by which miR-21 induces drug resistance to 5-fluorouracil (5-FU) in human pancreatic cancer cells (PATU8988 and PANC-1). We report that PATU8988 cells resistant to 5-FU express high levels of miR-21 in comparison to sensitive primary PATU8988 cells. Suppression of miR-21 expression in 5-Fu-resistant PATU8988 cells can alleviate its 5-FU resistance. Meanwhile, lentiviral vector-mediated overexpression of miR-21 not only conferred resistance to 5-FU but also promoted proliferation, migration, and invasion of PATU8988 and PANC-1 cells. The proresistance effects of miR-21 were attributed to the attenuated expression of tumor suppressor genes, including PTEN and PDCD4. Overexpression of PTEN and PDCD4 antagonized miR-21-induced resistance to 5-FU and migration activity. Our work demonstrates that miR-21 can confer drug resistance to 5-FU in pancreatic cancer cells by regulating the expression of tumor suppressor genes, as the target genes of miR-21, PTEN and PDCD4 can rescue 5-FU sensitivity and the phenotypic characteristics disrupted by miR-21.

Comprehensive molecular tumor profiling in radiation oncology: How it could be used for precision medicine

New technologies enabling the analysis of various molecules, including DNA, RNA, proteins and small metabolites, can aid in understanding the complex molecular processes in cancer cells. In particular, for the use of novel targeted therapeutics, elucidation of the mechanisms leading to cell death or survival is crucial to eliminate tumor resistance and optimize therapeutic efficacy. While some techniques, such as genomic analysis for identifying specific gene mutations or epigenetic testing of promoter methylation, are already in clinical use, other "omics-based" assays are still evolving. Here, we provide an overview of the current status of molecular profiling methods, including promising research strategies, as well as possible challenges, and their emerging role in radiation oncology.

MicroRNA Targeted Therapeutic Approach for Pancreatic Cancer

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

MicroRNA in pancreatic ductal adenocarcinoma and its precursor lesions

Pancreatic ductal adenocarcinoma (PDAC) is the 4^th deadliest cancer in the United States, due to its aggressive nature, late detection, and resistance to chemotherapy. The majority of PDAC develops from 3 precursor lesions, pancreatic intraepithelial lesions (PanIN), intraductual papillary mucinous neoplasm (IPMN), and mucinous cystic neoplasm. Early detection and surgical resection can increase PDAC 5-year survival rate from 6% for Stage IV to 50% for Stage I. To date, there are no reliable biomarkers that can detect PDAC. MicroRNAs (miRNA) are small noncoding RNAs (18-25 nucleotides) that regulate gene expression by affecting translation of messenger RNA (mRNA). A large body of evidence suggests that miRNAs are dysregulated in various types of cancers. MiRNA has been profiled as a potential biomarker in pancreatic tumor tissue, blood, cyst fluid, stool, and saliva. Four miRNA biomarkers (miR-21, miR-155, miR-196, and miR-210) have been consistently dysregulated in PDAC. MiR-21, miR-155, and miR-196 have also been dysregulated in IPMN and PanIN lesions suggesting their use as early biomarkers of this disease. In this review, we explore current knowledge of miRNA sampling, miRNA dysregulation in PDAC and its precursor lesions, and advances that have been made in using miRNA as a biomarker for PDAC and its precursor lesions.

Molecular targets for the treatment of pancreatic cancer: Clinical and experimental studies

Pancreatic cancer is the fourth most common cause of cancer deaths worldwide. Although recent therapeutic developments for patients with pancreatic cancer have provided survival benefits, the outcomes for patients with pancreatic cancer remain unsatisfactory. Molecularly targeted cancer therapy has advanced in the past decade with the use of a number of pathways as candidates of therapeutic targets. This review summarizes the molecular features of this refractory disease while focusing on the recent clinical and experimental findings on pancreatic cancer. It also discusses the data supporting current standard clinical outcomes, and offers conclusions that may improve the management of pancreatic cancer in the future.

The Role of MicroRNAs in Resistance to Current Pancreatic Cancer Treatment: Translational Studies and Basic Protocols for Extraction and PCR Analysis

Pancreatic ductal adenocarcinoma (PDAC) is a common cause of cancer death and has the worst prognosis of any major malignancy, with less than 5 % of patients alive 5-years after diagnosis. The therapeutic options for metastatic PDAC have changed in the past few years from single agent gemcitabine treatment to combination regimens. Nowadays, FOLFIRINOX or gemcitabine with nab-paclitaxel are new standard combinations in frontline metastatic setting in PDAC patients with good performance status. MicroRNAs (miRNA) are small, noncoding RNA molecules affecting important cellular processes such as inhibition of apoptosis, cell proliferation, epithelial-to-mesenchymal transition (EMT), metastases, and resistance to common cytotoxic and anti-signaling therapy in PDAC. A functional association between miRNAs and chemoresistance has been described for several common therapies. Therefore, in this review, we summarize the current knowledge on the role of miRNAs in the resistance to current anticancer treatment used for patients affected by metastatic PDAC.

MiR-194, commonly repressed in colorectal cancer, suppresses tumor growth by regulating the MAP4K4/c-Jun/MDM2 signaling pathway

Tumor growth cascade is a complicated and multistep process with numerous obstacles. Until recently, evidences have shown the involvement of microRNAs (miRNAs) in tumorigenesis and tumor progression of various cancers, including colorectal cancer (CRC). In this study, we explored the role of miR-194 and its downstream pathway in CRC. We acquired data through miRNA microarray profiles, showing that the expression of miR-194 was significantly suppressed in CRC tissues compared with corresponding noncancerous tissues. Decreased miR-194 expression was obviously associated with tumor size and tumor differentiation, as well as TNM stage. Both Kaplan-Meier and multivariate survival analysis showed that downregulated miR-194 was associated with overall survival. Moreover, functional assays indicated that overexpression of miR-194 in CRC cell lines inhibited cell proliferation both in vitro and in vivo. In addition, using dual-luciferase reporter gene assay, we found MAP4K4 was the direct target of miR-194. Silencing of MAP4K4 resulted in similar biological behavior changes to that of overexpression of miR-194. We also observed through Human Gene Expression Array that MDM2 was one of the downstream targets of MAP4K4. Knockdown of MAP4K4 downregulated MDM2 expression through transcription factor c-Jun binding to the -1063 to -1057 bp of the promoter. These results suggest that miR-194, regulating the MAP4K4/c-Jun/MDM2 signaling pathway, might act as a tumor suppressor and serve as a novel target for CRC prevention and therapy.

MicroRNA-100 and microRNA-21 as markers of survival and chemotherapy response in pancreatic ductal adenocarcinoma UICC stage II

Background

Pancreatic ductal adenocarcinoma (PDAC) remains a highly chemoresistant tumor entity for which no reliable molecular targets exist to predict or influence the success of chemotherapy. Recently, we identified a panel of microRNAs associated with induced gemcitabine chemoresistance in human PDAC cell lines. This clinical study evaluates these microRNAs and associated molecular markers as prognostic markers of outcome in 98 PDAC patients Union Internationale Contre le Cancer (UICC) stage II undergoing curative surgery with adjuvant gemcitabine chemotherapy. The primary end points of this study are recurrence-free survival and overall survival.

Results

Poor response to chemotherapy was significantly correlated to overexpression of microRNA-21 (p = 0.029), microRNA-99a (p = 0.037), microRNA-100 (p = 0.028), and microRNA-210 (p = 0.021) in tissue samples of PDAC patients UICC stage II. Upregulation of these microRNAs was associated with a significantly shorter overall survival and recurrence-free survival (p < 0.05). Overexpression of phosphatase and tensin homolog (PTEN) (p = 0.039) and low expression of multidrug resistance (MDR)-1 (p = 0.043) and breast cancer resistance protein (BCRP)-1 (p = 0.038) were significantly correlated to improved response to adjuvant chemotherapy. Adjuvant gemcitabine treatment (p < 0.0001) and low tumor grading (p = 0.047) were correlated to better outcome. MicroRNA-100, microRNA-21, and its targets PTEN and MDR-1 were independent factors of survival in multivariate analysis.

Conclusions

Multivariate survival analyses identified microRNA-21 and microRNA-100 as unfavorable prognostic factors in resected and adjuvant treated PDAC UICC stage II patients.

miRNAs As Diagnostic and Prognostic Biomarkers in Pancreatic Ductal Adenocarcinoma and Its Precursor Lesions: A Review

Pancreatic ductal adenocarcinoma (PDAC), a rare but lethal tumor, is difficult to diagnose without performing an invasive procedure. miRNAs are known to be deregulated in PDAC patients, and recent studies have shown that they can be used as diagnostic and prognostic of the disease. The detection of miRNAs in samples acquired through minimally or noninvasive procedures, such as serum, plasma, and saliva, can have a positive impact on the clinical management of these patients. This article is a comprehensive review of the major studies that have evaluated the expression of miRNAs as biomarkers in pancreatic cancer and its premalignant lesions.