miRNA-181b increases the sensitivity of pancreatic ductal adenocarcinoma cells to gemcitabine in vitro and in nude mice by targeting BCL-2

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.

Extracellular Vesicular miRNA in Pancreatic Cancer: From Lab to Therapy

Pancreatic cancer is a prevalent lethal gastrointestinal cancer that generally does not show any symptoms until it reaches advanced stages, resulting in a high mortality rate. People at high risk, such as those with a family history or chronic pancreatitis, do not have a universally accepted screening protocol. Chemotherapy and radiotherapy demonstrate limited effectiveness in the management of pancreatic cancer, emphasizing the urgent need for innovative therapeutic strategies. Recent studies indicated that the complex interaction among pancreatic cancer cells within the dynamic microenvironment, comprising the extracellular matrix, cancer-associated cells, and diverse immune cells, intricately regulates the biological characteristics of the disease. Additionally, mounting evidence suggests that EVs play a crucial role as mediators in intercellular communication by the transportation of different biomolecules, such as miRNA, proteins, DNA, mRNA, and lipids, between heterogeneous cell subpopulations. This communication mediated by EVs significantly impacts multiple aspects of pancreatic cancer pathogenesis, including proliferation, angiogenesis, metastasis, and resistance to therapy. In this review, we delve into the pivotal role of EV-associated miRNAs in the progression, metastasis, and development of drug resistance in pancreatic cancer as well as their therapeutic potential as biomarkers and drug-delivery mechanisms for the management of pancreatic cancer.

Differential Sensitivity to Ionizing Radiation in Gemcitabine-Resistant and Paclitaxel-Resistant Pancreatic Cancer Cells

PURPOSE

Chemoresistance remains a major challenge in treating pancreatic ductal adenocarcinoma (PDAC). Although chemoradiation has proven effective in other tumor types, such as head and neck squamous cell carcinoma, its role in PDAC and effect on acquired chemoresistance have yet to be fully explored. In this study, we investigated the sensitivity of gemcitabine-resistant (GR) and paclitaxel-resistant (PR) PDAC cells to ionizing radiation (IR) and their underlying mechanisms.

METHODS AND MATERIALS

GR and PR clones were generated from PANC-1, PATU-T, and SUIT2-007 pancreatic cancer cell lines. Cell survival after radiation was assessed using clonogenic assay, sulforhodamine B assay, apoptosis, and spheroid growth by bioluminescence. Radiation-induced DNA damage was assessed using Western blot, extra-long polymerase chain reaction, reactive oxygen species production, and immunofluorescence. Autophagy and modulation of the Hippo signaling pathway were investigated using proteomics, Western blot, immunofluorescence, and reverse-transcription quantitative polymerase chain reaction.

RESULTS

In both 2- and 3-dimensional settings, PR cells were more sensitive to IR and showed decreased β-globin amplification, indicating more DNA damage accumulation compared with GR or wild-type cells after 24 hours. Proteomic analysis of PR PATU-T cells revealed that the protein MST4, a kinase involved in autophagy and the Hippo signaling pathway, was highly downregulated. A differential association was found between autophagy and radiation treatment depending on the cell model. Interestingly, increased yes-associated protein nuclear localization and downstream Hippo signaling pathway target gene expression were observed in response to IR.

CONCLUSIONS

This was the first study investigating the potential of IR in targeting PDAC cells with acquired chemoresistance. Our results demonstrate that PR cells exhibit enhanced sensitivity to IR due to greater accumulation of DNA damage. Additionally, depending on the specific cellular context, radiation-induced modulation of autophagy and the Hippo signaling pathway emerged as potential underlying mechanisms, findings with potential to inform personalized treatment strategies for patients with acquired chemoresistance.

miRNAs Role in Wilms tumor pathogenesis: Signaling pathways interplay

Wilms' tumors (WTs) are the most common type of kidney tumor in children, and a negative outlook is generally associated with widespread anaplastic. MicroRNAs (miRNAs) are crucial in the development of WT by regulating the expression of specific genes. There is an increasing amount of research that connects the dysregulation of miRNAs to the development of various renal illnesses. The conditions encompassed are renal fibrosis, renal cancers, and chronic and polycystic kidney disease. Dysregulation of several important miRNAs, either oncogenic or tumor-suppressing, has been found in WT. The present state of knowledge on the involvement of dysregulated miRNAs in the progression of WT is summarized in this review.

Microbiome and MicroRNA or Long Non-Coding RNA-Two Modern Approaches to Understanding Pancreatic Ductal Adenocarcinoma

Pancreatic ductal adenocarcinoma (PDAC) is one of humans' most common and fatal neoplasms. Nowadays, a number of PDAC studies are being conducted in two different fields: non-coding RNA (especially microRNA and long non-coding RNA) and microbiota. It has been recently discovered that not only does miRNA affect particular bacteria in the gut microbiome that can promote carcinogenesis in the pancreas, but the microbiome also has a visible impact on the miRNA. This suggests that it is possible to use the combined impact of the microbiome and noncoding RNA to suppress the development of PDAC. Nevertheless, insufficient research has focused on bounding both approaches to the diagnosis, treatment, and prevention of pancreatic ductal adenocarcinoma. In this article, we summarize the recent literature on the molecular basis of carcinogenesis in the pancreas, the two-sided impact of particular types of non-coding RNA and the pancreatic cancer microbiome, and possible medical implications of the discovered phenomenon.

Nanoparticle-Mediated Therapy with miR-198 Sensitizes Pancreatic Cancer to Gemcitabine Treatment through Downregulation of VCP-Mediated Autophagy

Pancreatic ductal adenocarcinoma (PDAC) remains an extremely aggressive disease characterized by rapidly acquired multi-drug resistance, including to first-line chemotherapeutic agent gemcitabine. Autophagy is a process that is often exploited by cancer and is one of several intrinsic factors associated with resistance to gemcitabine. We have previously found that miR-198 acts as a tumor suppressor in PDAC through the targeting of factors including Valosin-containing protein (VCP). VCP has been reported to play an important role in autophagic flux. In this study, we investigated whether the repression of VCP through miR-198 administration disrupts the autophagy process and sensitizes PDAC cells to gemcitabine treatment in vitro. Moreover, we used LGA-PEI (LPNP) nanoparticles to effectively administer miR-198 to tumors in vivo, inducing tumor sensitization to gemcitabine and leading to a significant reduction in tumor burden and metastases and a concomitant downregulation of VCP expression and autophagy maturation. Our results indicate a potential therapeutic strategy for targeting gemcitabine resistant PDAC and establishes the use of LPNPs for effective therapeutic delivery of nucleic acids in vitro and in vivo.

Noncoding RNAs: an emerging modulator of drug resistance in pancreatic cancer

Pancreatic cancer is the eighth leading cause of cancer-related deaths worldwide. Chemotherapy including gemcitabine, 5-fluorouracil, adriamycin and cisplatin, immunotherapy with immune checkpoint inhibitors and targeted therapy have been demonstrated to significantly improve prognosis of pancreatic cancer patients with advanced diseases. However, most patients developed drug resistance to these therapeutic agents, which leading to shortened patient survival. The detailed molecular mechanisms contributing to pancreatic cancer drug resistance remain largely unclear. The growing evidences have shown that noncoding RNAs (ncRNAs), including microRNAs (miRNAs), long noncoding RNAs (lncRNAs) and circular RNAs (circRNAs), are involved in pancreatic cancer pathogenesis and development of drug resistance. In the present review, we systematically summarized the new insight on of various miRNAs, lncRNAs and circRNAs on drug resistance of pancreatic cancer. These results demonstrated that targeting the tumor-specific ncRNA may provide novel options for pancreatic cancer treatments.

Circulating miRNA Expression Profiles and Machine Learning Models in Association with Response to Irinotecan-Based Treatment in Metastatic Colorectal Cancer

Colorectal cancer represents a leading cause of cancer-related morbidity and mortality. Despite improvements, chemotherapy remains the backbone of colorectal cancer treatment. The aim of this study is to investigate the variation of circulating microRNA expression profiles and the response to irinotecan-based treatment in metastatic colorectal cancer and to identify relevant target genes and molecular functions. Serum samples from 95 metastatic colorectal cancer patients were analyzed. The microRNA expression was tested with a NucleoSpin miRNA kit (Machnery-Nagel, Germany), and a machine learning approach was subsequently applied for microRNA profiling. The top 10 upregulated microRNAs in the non-responders group were hsa-miR-181b-5p, hsa-miR-10b-5p, hsa-let-7f-5p, hsa-miR-181a-5p, hsa-miR-181d-5p, hsa-miR-301a-3p, hsa-miR-92a-3p, hsa-miR-155-5p, hsa-miR-30c-5p, and hsa-let-7i-5p. Similarly, the top 10 downregulated microRNAs were hsa-let-7d-5p, hsa-let-7c-5p, hsa-miR-215-5p, hsa-miR-143-3p, hsa-let-7a-5p, hsa-miR-10a-5p, hsa-miR-142-5p, hsa-miR-148a-3p, hsa-miR-122-5p, and hsa-miR-17-5p. The upregulation of microRNAs in the miR-181 family and the downregulation of those in the let-7 family appear to be mostly involved with non-responsiveness to irinotecan-based treatment.

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.

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.

Noncoding RNAs in drug-resistant pancreatic cancer: A review

Pancreatic cancer is the fourth-leading cause of cancer-related deaths and is expected to be the second-leading cause of cancer-related deaths in Europe and the United States by 2030. The high fatality rate of pancreatic cancer is ascribed to untimely diagnosis, early metastasis and limited responses to both chemotherapy and radiotherapy. Although gemcitabine, 5-fluorouracil and some other drugs can profoundly improve patient prognosis, most pancreatic cancer patients eventually develop drug resistance, leading to poor clinical outcomes. The underlying mechanisms of pancreatic cancer drug resistance are complicated and inconclusive. Interestingly, accumulating evidence has demonstrated that different noncoding RNAs (ncRNAs), such as microRNAs (miRNAs), long noncoding RNAs (lncRNAs) and circular RNAs (circRNAs), play a crucial role in pancreatic cancer resistance to chemotherapy reagents. In this paper, we systematically summarize the molecular mechanism underlying the influence of ncRNAs on the generation and development of drug resistance in pancreatic cancer and discuss the potential role of ncRNAs as prognostic markers and new therapeutic targets for pancreatic cancer.

microRNA-181 serves as a dual-role regulator in the development of human cancers

MicroRNAs (miRNAs) as the regulatory short noncoding RNAs are involved in a wide array of cellular and molecular processes. They negatively regulate gene expression and their dysfunction is correlated with cancer development through modulation of multiple signaling pathways. Therefore, these molecules could be considered as novel biomarkers and therapeutic targets for more effective management of human cancers. Recent studies have demonstrated that the miR-181 family is dysregulated in various tumor tissues and plays a pivotal role in carcinogenesis. They have been shown to act as oncomirs or tumor suppressors considering their mRNA targets and to be involved in cell proliferation, apoptosis, autophagy, angiogenesis and drug resistance. Additionally, these miRNAs have been demonstrated to exert their regulatory effects through modulating multiple signaling pathways including PI3K/AKT, MAPK, TGF-b, Wnt, NF-κB, Notch pathways. Given that, in this review, we briefly summarise the recent studies that have focused on the roles of miRNA-181 family as the multifunctional miRNAs in tumorigenesis and cancer development. These miRNAs may serve as diagnostic and prognostic biomarkers or therapeutic targets in human cancer gene therapy.

miR-181b/Oncostatin m axis inhibits prostate cancer bone metastasis via modulating osteoclast differentiation

The activation of osteoblasts is significantly correlated to prostate tumor bone metastasis and bone loss. Oncostatin M (OSM) could promote breast cancer metastasis to bone. However, its role and mechanism in prostate cancer bone metastasis remain unclear. MicroRNAs (miRNAs) could play important roles in cancers via post-transcriptionally regulating target genes via binding to specific sequences in the 3' UTR of downstream target genes. In the present study, we performed microarray profiling analyses to identify differentially-expressed miRNAs in preosteoclast before and after osteoclast differentiation that could target OSM. miR-181b-5p was downregulated during Raw264.7 cells differentiation into osteoclast. By direct targeting OSM 3' UTR, miR-181b-5p inhibited OSM messenger RNA expression and protein levels, subsequently decreasing IL-6 and AREG and increasing OPG, while OSM overexpression exerted an opposing effect. More importantly, co-culture with miR-181b-5p-overexpressing differentiated Raw264.7 cells suppressed proliferation, migration, and invasion of mouse prostate cancer RM-1 cells, while co-culture with OSM-overexpressing Raw264.7 cells led to opposing cellular effects. More importantly, the effects of miR-181b-5p on osteoclastogenic factors and RM-1 cells could be significantly reversed by OSM overexpression. In summary, miR-181b-5p/OSM axis could be a viable therapeutic target for patients with surgically removed primary tumors to reduce bone metastasis and prevent bone loss.

miRNA and Gene Expression in Pancreatic Ductal Adenocarcinoma

Pancreatic ductal adenocarcinoma (PDAC) remains a challenging disease that is mostly diagnosed late in the course of the illness. Unlike other cancers in which measurable successes have been achieved with traditional chemotherapy, targeted therapy, and, recently, immunotherapy, PDAC has proved to be poorly responsive to these treatments, with only marginal to modest incremental benefits using conventional cytotoxic therapy. There is, therefore, a great unmet need to develop better therapies based on improved understanding of biology and identification of predictive and prognostic biomarkers that would guide therapy. miRNAs are small noncoding RNAs that regulate the expression of some key genes by targeting their 3'-untranslated mRNA region. Aberrant expression of miRNAs has been linked to the development of various malignancies, including PDAC. A series of miRNAs have been identified as potential tools for early diagnosis, prediction of treatment response, and prognosis of patients with PDAC. In this review, we present a summary of the miRNAs that have been studied in PDAC in the context of disease biology.

Pancreatic cancer chemo-resistance is driven by tumor phenotype rather than tumor genotype

Pancreatic Ductal Adenocarcinoma (PDAC) is one of the deadliest forms of cancer. A major reason for this situation is the fact that these tumors are already resistant or become rapidly resistant to all conventional therapies. Like any transformation process, initiation and development of PDCA are driven by a well known panel of genetic alterations, few of them are shared with most cancers, but many mutations are specific to PDAC and are partially responsible for the great inter-tumor heterogeneity. Importantly, this knowledge has been inefficient in predicting response to anticancer therapy, or in establishing diagnosis and prognosis. Hence, the pre-existing or rapidly acquired resistance of pancreatic cancer cells to therapeutic drugs rely on other parameters and features developed by the cells and/or the micro-environment, that are independent of their genetic profiles. This review sheds light on all major phenotypic, non genetic, alterations known to play important roles in PDAC cells resistance to treatments and therapeutic escape.

MiR-181b-5p modulates chemosensitivity of glioma cells to temozolomide by targeting Bcl-2

Chemotherapy is the main postsurgical and adjuvant therapy for glioma, and intrinsic or acquired temozolomide (TMZ) resistance may result in poor prognosis. The miR-181 family was discovered to play an important role in regulating biological functions in glioma, and miR-181b is less expressed in human gliomas as a tumor-suppressive miRNA. The aim of this study was to explore the molecular mechanism of miR-181b-5p and its target gene on modulating TMZ chemosensitivity in glioma cells. The enhanced chemosensitivity effect of miR-181b-5p to TMZ in glioma cells U87MG and U251 was detected by MTT method. Dual luciferase reporter assay, quantitative real-time PCR (qRT-PCR) and Western blotting were performed to demonstrate that miR-181b-5p directly targets Bcl-2 to reduce the expression. Transwell and flow cytometry assays showed that combination of miR-181b-5p and TMZ exerted stronger effects on inhibiting U87MG cells proliferation, migration and invasion as well as promoting apoptosis and S phase arrest than miR-181b-5p and TMZ alone. The same tendency was observed in the upregulation of apoptosis-related protein Bax and downregulation of cycle-related proteins CyclinD1 and CDK4. In vivo experiments indicated that miR-181b-5p could enhance the tumor-suppressive effect of TMZ. In conclusion, our findings indicate that upregulation of miR-181b-5p targets Bcl-2 directly and may function as an important modifier to sensitize glioma cells to TMZ.

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.

miR-34 increases in vitro PANC-1 cell sensitivity to gemcitabine via targeting Slug/PUMA

miR-34 was deregulated in tumor tissues compared with corresponding noncancerous tissue samples. Furthermore, miR-34 may contribute to cancer-stromal interaction associated with cancer progression. However, whether miR-34 could decrease chemoresistance of cancer cells to chemotherapeutic agent remains unclear. In our study, we examined whether overexpression of miR-34 could sensitize gemcitabine -mediated apoptosis in human pancreatic cancer PANC-1 cells. We found that miR-34 markedly induced gemcitabine -mediated apoptosis in PANC-1 cells. miR-34 induced down-regulation of Slug expression and upregulation of p53 up-regulated modulator of apoptosis (PUMA) expression. The over-expression of Slug or downregulation of PUMA by Slug cDNA or PUMA siRNA transfection markedly blocked miR-34-induced gemcitabine sensitization. Furthermore, miR-34 induced PUMA expression by downregulation of Slug. Taken together, our study demonstrates that miR-34 enhances sensitization against gemcitabine-mediated apoptosis through the down-regulation of Slug expression, and up-regulation of Slug-dependent PUMA expression.

miR-125a-3p is responsible for chemosensitivity in PDAC by inhibiting epithelial-mesenchymal transition via Fyn

BACKGROUND

Pancreatic ductal adenocarcinoma (PDAC) is one of the most lethal cancers and resistance to cytotoxic chemotherapy is the major cause of mortality in PDAC patients. miR-125a-3p was found to be down-regulated in PDAC cells; however, the function of miR-125a-3p in PDAC has been elusive. Here, we explored the role of miR-125a-3p in chemosensitivity in PDAC cells.

METHODS

We used qRT-PCR to detect miR-125a-3p expression in two PDAC cell lines. And we measured cell viability and apoptosis by MTT assay and flow cytometry, respectively. Scratch wound healing assay and transwell invasion assay were used to test the effects of miR-125a-3p and Fyn on cell EMT process. In addition, we validated the interaction of miR-125a-3p and Fyn by dual luciferase reporter assay. qRT-PCR and western blot were used to detect the mRNA and protein expressions of E-cadhrein, N-cadhrein, Snail and Fyn.

RESULTS

We found that miR-125a-3p was down-regulated in a time-dependent manner following treatment with gemcitabine in PDAC cells. Meanwhile, we found that overexpression of miR-125a-3p significantly increased chemosensitivity to gemcitabine and suppressed epithelial-mesenchymal transition (EMT) of PDAC cells. Mechanistically, miR-125a-3p directly targeted Fyn and decreased the expression of Fyn that functions to promote EMT process in PDAC. Furthermore, overexpression of Fyn could partially reverse the effects of miR-125a-3p on chemosensitivity to gemcitabine.

CONCLUSION

Our study is the first to show that miR-125a-3p is responsible for chemosensitivity in PDAC and could inhibit epithelial-mesenchymal transition by directly targeting Fyn. This provides a novel potential therapeutic strategy to overcome chemoresistance in PDAC.

MicroRNA-1291 targets the FOXA2-AGR2 pathway to suppress pancreatic cancer cell proliferation and tumorigenesis

Pancreatic cancer is the fourth leading cause of cancer death in the United States. Better understanding of pancreatic cancer biology may help identify new oncotargets towards more effective therapies. This study investigated the mechanistic actions of microRNA-1291 (miR-1291) in the suppression of pancreatic tumorigenesis. Our data showed that miR-1291 was downregulated in a set of clinical pancreatic carcinoma specimens and human pancreatic cancer cell lines. Restoration of miR-1291 expression inhibited pancreatic cancer cell proliferation, which was associated with cell cycle arrest and enhanced apoptosis. Furthermore, miR-1291 sharply suppressed the tumorigenicity of PANC-1 cells in mouse models. A proteomic profiling study revealed 32 proteins altered over 2-fold in miR-1291-expressing PANC-1 cells that could be assembled into multiple critical pathways for cancer. Among them anterior gradient 2 (AGR2) was reduced to the greatest degree. Through computational and experimental studies we further identified that forkhead box protein A2 (FOXA2), a transcription factor governing AGR2 expression, was a direct target of miR-1291. These results connect miR-1291 to the FOXA2-AGR2 regulatory pathway in the suppression of pancreatic cancer cell proliferation and tumorigenesis, providing new insight into the development of miRNA-based therapy to combat pancreatic cancer.

MicroRNA-410-3p attenuates gemcitabine resistance in pancreatic ductal adenocarcinoma by inhibiting HMGB1-mediated autophagy

Gemcitabine-based chemotherapy is the most common treatment option for pancreatic ductal adenocarcinoma (PDAC). However, it offers little therapeutic value in many cases due to the rapid development of chemoresistance. MicroRNAs (miRNAs) have been found to play pivotal roles in the chemotherapeutic resistance of PDAC. We found that miR-410-3p was significantly down-regulated in human pancreatic cancer xenograft (HPCx) tumor tissues from gemcitabine-treated mice. Low miR-410-3p expression correlated with gemcitabine resistance in HPCx tumors and PDAC cells as well as poor prognosis in PDAC patients. We also found that miR-410-3p attenuated the gemcitabine resistance of PDAC by targeting the 3'-UTR of HMGB1. Moreover, our study clearly demonstrated that miR-410-3p enhanced chemosensitivity to gemcitabine via inhibiting HMGB1-induced autophagy during chemotherapy in PDAC cells. Our study suggests that miR-410-3p expression may be a useful indicator of the potential for chemoresistance to gemcitabine and provide a potential new therapeutic target for chemoresistance in PDAC.

Cancer Hallmarks and MicroRNAs: The Therapeutic Connection

Human cancers are characterized by a number of hallmarks, including sustained proliferative signaling, evasion of growth suppressors, activated invasion and metastasis, replicative immortality, angiogenesis, resistance to cell death, and evasion of immune destruction. As microRNAs (miRNAs) are deregulated in virtually all human cancers, they show involvement in each of the cancer hallmarks as well. In this chapter, we describe the involvement of miRNAs in cancer from a cancer hallmarks and targeted therapeutics point of view. As no miRNA-based cancer therapeutics are available to date, and the only clinical trial on miRNA-based cancer therapeutics (MRX34) was terminated prematurely due to serious adverse events, we are focusing on protein-coding miRNA targets for which targeted therapeutics in oncology are already approved by the FDA. For each of the cancer hallmarks, we selected major protein-coding players and describe the miRNAs that target them.

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

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

MiR-451 Promotes Cell Proliferation and Metastasis in Pancreatic Cancer through Targeting CAB39

Emerging evidence shows that microRNAs (miRNAs) play important roles in the regulation of various biological and pathologic processes in human cancers and the aberrant expression of miRNAs contributes to the tumor development. In this study, our findings indicate that miR-451 is significantly overexpressed in pancreatic cancer tissues and cell lines and elevated expression of miR-451 contributes to promoted cell viability (in vitro and in vivo). Moreover, overexpression of miR-451 is closely linked to poor prognosis and lymphatic metastasis. Inhibition of miR-451 dramatically suppresses cell viability and invasion, promotes cell apoptosis, and induces cell cycle arrest. Furthermore, miR-451 directly targets CAB39 and negatively regulates its expression and inhibition of CAB39 contributes to the promoted cell viability and invasion. Our findings improve our understanding of the function of miR-451 in the identification and therapy of pancreatic cancer.

MicroRNA-181b inhibits glycolysis in gastric cancer cells via targeting hexokinase 2 gene

Cancer cells usually utilize glucose as a carbon source for aerobic glycolysis, which is named as ``Warburg effect''. Recent studies have shown that MicroRNAs (miRNAs), a class of short and non-coding RNAs, play a role in the regulation of metabolic reprograming in cancer cells. In the present study, we report that miR-181b negatively regulates glycolysis in gastric cancer cells. Over-expression of miR-181b mimics reduces the glucose uptake and lactate production, while increasing the cellular ATP levels in NCI-N87 and MGC80-3 cells. At the molecular level, miR-181b directly inhibits the expression level of hexokinase 2 (HK2), a key enzyme that catalyzes the first step of glycolysis, through targeting its 3'-untranslated region. In addition, miR-181b represses cell proliferation and migration and is dramatically down-regulated in human gastric cancers. Therefore, our data disclose a novel function of miR-181b in reprogramming the metabolic process in gastric cancer.

MicroRNA-181b is downregulated in non-small cell lung cancer and inhibits cell motility by directly targeting HMGB1

The expression of microRNA-181b (miR-181b) has been investigated in various human cancers. However, the expression and functions of miR-181b in non-small cell lung cancer (NSCLC) are yet to be studied. In the present study, miR-181b expression in NSCLC tissues and cell lines was analyzed by quantitative polymerase chain reaction, and was shown to be recurrently downregulated. Following transfection of the H23 and H522 NSCLC cells lines with miR-181b, cell migration and cell invasion assays were performed to evaluate the effect of miR-181b overexpression on the cell motility. It was demonstrated that overexpression of miR-181b inhibited the migration and invasion of NSCLC cells. Subsequently, bioinformatics analysis, western blotting and luciferase reporter assays were conducted to investigate the mechanism underlying the miR-181b-mediated inhibition of NSCLC cell motility. It was found that miR-181b directly targeted high-mobility group box-1 (HMGB1) in NSCLC cells. These results reveal a novel therapeutic target, the miR-181b/HMGB1 axis, in NSCLC. Treatment approaches targeting this axis will be beneficial to prevent NSCLC from becoming invasive.

Combining miRNA and mRNA Expression Profiles in Wilms Tumor Subtypes

Wilms tumor (WT) is the most common childhood renal cancer. Recent findings of mutations in microRNA (miRNA) processing proteins suggest a pivotal role of miRNAs in WT genesis. We performed miRNA expression profiling of 36 WTs of different subtypes and four normal kidney tissues using microarrays. Additionally, we determined the gene expression profile of 28 of these tumors to identify potentially correlated target genes and affected pathways. We identified 85 miRNAs and 2107 messenger RNAs (mRNA) differentially expressed in blastemal WT, and 266 miRNAs and 1267 mRNAs differentially expressed in regressive subtype. The hierarchical clustering of the samples, using either the miRNA or mRNA profile, showed the clear separation of WT from normal kidney samples, but the miRNA pattern yielded better separation of WT subtypes. A correlation analysis of the deregulated miRNA and mRNAs identified 13,026 miRNA/mRNA pairs with inversely correlated expression, of which 2844 are potential interactions of miRNA and their predicted mRNA targets. We found significant upregulation of miRNAs-183, -301a/b and -335 for the blastemal subtype, and miRNAs-181b, -223 and -630 for the regressive subtype. We found marked deregulation of miRNAs regulating epithelial to mesenchymal transition, especially in the blastemal subtype, and miRNAs influencing chemosensitivity, especially in regressive subtypes. Further research is needed to assess the influence of preoperative chemotherapy and tumor infiltrating lymphocytes on the miRNA and mRNA patterns in WT.

Developments in miRNA gene signaling pathways in pancreatic cancer

Pancreatic cancer is a devastating malignancy that ranks as the fourth leading cause of cancer-related deaths worldwide. Dismal prognosis is mainly attributable to limited knowledge of the molecular pathogenesis of the disease. miRNAs have been found to be deregulated in pancreatic cancer, affecting several steps of initiation and aggressiveness of the disease by regulating important signaling pathways, such as the KRAS and Notch pathways. Moreover, the effect of miRNAs on regulating cell cycle events and expression of transcription factors has gained a lot of attention. Recent studies have highlighted the application of miRNAs as biomarkers and therapeutic tools. The current review focuses on latest advances with respect to the roles of miRNAs in pancreatic ductal adenocarcinoma associated signaling pathways and miRNA-based therapeutics.

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.

Construction and analysis of three networks of genes and microRNAs in adenocarcinoma

Adenocarcinoma is one of the most serious diseases that threaten human health. Numerous studies have investigated adenocarcinoma and have obtained a considerable amount of data regarding genes and microRNA (miRNA) in adenocarcinoma. However, studies have only focused on one or a small number of genes and miRNAs, and the data is stored in a scattered form, making it challenging to summarize and assess the associations between the genes and miRNAs. In the present study, three networks of genes and miRNAs in adenocarcinoma were focused on. This enabled the construction of networks of elements involved in adenocarcinoma and the analysis of these networks, rather than only discussing one gene. Transcription factors (TFs), miRNAs, and target and host genes of miRNAs in adenocarcinoma, and the regulatory associations between these elements were identified in the present study. These elements and associations were then used to construct three networks, which consisted of the differentially-expressed, associated and global networks. The similarities and differences between the three networks were compared and analyzed. In total, 3 notable TFs, consisting of TP53, phosphatase and tensin homolog and SMAD4, were identified in adenocarcinoma. These TFs were able to regulate the differentially-expressed genes and the majority of the differentially-expressed miRNAs. Certain important regulatory associations were also found in adenocarcinoma, in addition to self-regulating associations between TFs and miRNAs. The upstream and downstream elements of the differentially-expressed genes and miRNAs were recorded, which revealed the regulatory associations between genes and miRNAs. The present study clearly revealed components of the pathogenesis of adenocarcinoma and the regulatory associations between the elements in adenocarcinoma. The present study may aid the investigation of gene therapy in adenocarcinoma and provides a theoretical basis for studies of gene therapy methods as a treatment for adenocarcinoma.

MicroRNA Signaling Pathway Network in Pancreatic Ductal Adenocarcinoma

Pancreatic ductal adenocarcinoma (PDAC) is considered to be the most lethal and aggressive malignancy with high mortality and poor prognosis. Their responses to current multimodal therapeutic regimens are limited. It is urgently needed to identify the molecular mechanism underlying pancreatic oncogenesis. Twelve core signaling cascades have been established critical in PDAC tumorigenesis by governing a wide variety of cellular processes. MicroRNAs (miRNAs) are aberrantly expressed in different types of tumors and play pivotal roles as post-transcriptional regulators of gene expression. Here, we will describe how miRNAs regulate different signaling pathways that contribute to pancreatic oncogenesis and progression.

Roles of microRNA-146a and microRNA-181b in regulating the secretion of tumor necrosis factor-α and interleukin-1β in silicon dioxide-induced NR8383 rat macrophages

Despite increasing evidence to suggest that microRNA (miR)-146a and miR-181b are involved in the regulation of immune responses and tumor progression, their roles in silicosis remain to be fully elucidated. Therefore, the present study examined the roles of miR-146a and miR-181b in inflammatory responses, and their effect on the expression of the tumor necrosis factor-α (TNF-α) and interleukin-1β (IL-1β) inflammatory chemokines in silicon dioxide (SiO₂)-induced NR8383 rat macrophages. Alterations in the expression levels of miR-146a and miR-181b in rats with silicosis have been previously investigated using miRNA arrays. In the present study, the expression levels of miR-146a and miR-181b were assessed using reverse transcription-quantitative polymerase chain reaction (RT-qPCR). The NR8383 cells were transfected with miRNA-146a and miR-181b mimics or inhibitors, and the cells and culture supernatants were collected following SiO₂ treatment for 12 h. The expression levels of TNF-α and IL-1β were detected using western blotting, RT-qPCR and ELISA. Analysis of variance and Student's two-tailed t-test were used to perform statistical analyses. The expression level of miR-146a was significantly increased, while the expression level of miR-181b was significantly decreased in the fibrotic lungs of the rats with silicosis, compared with the levels in the normal rats. It was observed that, following treatment of the NR8383 cells with SiO₂ for 12 h, the levels of TNF-α were significantly increased following miR-181b knockdown and the levels of IL-1β were significantly increased following miR-146a knockdown, compared with the inhibitor-treated controls (P<0.05). By contrast, miR-181b mimic transfection led to a significant reduction in the levels of TNF-α (P<0.05), and miR-146a mimics were responsible for the decrease in IL-1β (P<0.05). The results of the present study provide evidence supporting the roles of miR-146a and miR-181b in the pathogenesis of silicosis, and suggest that they may be candidate therapeutic target in this disease.

miRNAs in pancreatic cancer: therapeutic potential, delivery challenges and strategies

Pancreatic ductal adenocarcinoma (PDAC) is a severe pancreatic malignancy and is predicted to victimize 1.5% of men and women during their lifetime (Cancer statistics: SEER stat fact sheet, National Cancer Institute, 2014). miRNAs have emerged as a promising prognostic, diagnostic and therapeutic tool to fight against pancreatic cancer. miRNAs could modulate gene expression by imperfect base-pairing with target mRNA and hence provide means to fine-tune multiple genes simultaneously and alter various signaling pathways associated with the disease. This exceptional miRNA feature has provided a paradigm shift from the conventional one drug one target concept to one drug multiple target theory. However, in vivo miRNA delivery is not fully realized due to challenges posed by this special class of therapeutic molecules, which involves thorough understanding of the biogenesis and physicochemical properties of miRNA and delivery carriers along with the pathophysiology of the PDAC. This review highlights the delivery strategies of miRNA modulators (mimic/inhibitor) in cancer with special emphasis on PDAC since successful delivery of miRNA in vivo constitutes the major challenge in clinical translation of this promising class of therapeutics.

MiR-181b-5p downregulates NOVA1 to suppress proliferation, migration and invasion and promote apoptosis in astrocytoma

MicroRNAs (miRNAs) are small, short noncoding RNAs that modulate the expression of numerous genes by targeting their mRNA. Numerous abnormal miRNA expression patterns are observed in various human malignancies, and certain miRNAs can act as oncogenes or tumor suppressors. Astrocytoma, the most common neuroepithelial cancer, represents the majority of malignant brain tumors in humans. In our previous studies, we found that the downregulation of miR-181b-5p in astrocytomas is associated with a poor prognosis. The aim of the present study was to investigate the functional role of miR-181b-5p and its possible target genes. miR-181b-5p was significantly downregulated in astrocytoma specimens, and the reduced expression of miR-181b-5p was inversely correlated with the clinical stage. The ectopic expression of miR-181b-5p inhibited proliferation, migration and invasion and induced apoptosis in astrocytoma cancer cells in vitro. The NOVA1 (neuro-oncological ventral antigen 1) gene was further identified as a novel direct target of miR-181b-5p. Specifically, miR-181b-5p bound directly to the 3'-untranslated region (UTR) of NOVA1 and suppressed its expression. In clinical specimens, NOVA1 was overexpressed, and its protein levels were inversely correlated with miR-181b-5p expression. Furthermore, the changing level of NOVA1 was significantly associated with a poor survival outcome. Similar to restoring miR-181b-5p expression, downregulating NOVA1 inhibited cell growth, migration and invasion. Overexpression of NOVA1 reversed the inhibitory effects of miR-181b-5p. Our results indicate that miR-181b-5p is a tumor suppressor in astrocytoma that inhibits tumor progression by targeting NOVA1. These findings suggest that miR-181b-5p may serve as a novel therapeutic target for astrocytoma.

MicroRNAs: novel players in cancer diagnosis and therapies

First discovered in 1993, microRNAs (miRNAs) have been one of the hottest research areas over the past two decades. Oftentimes, miRNAs levels are found to be dysregulated in cancer patients. The potential use of miRNAs in cancer therapies is an emerging and promising field, with research finding miRNAs to play a role in cancer initiation, tumor growth, and metastasis. Therefore, miRNAs could become an integral part from cancer diagnosis to treatment in future. This review aims to examine current novel research work on the potential roles of miRNAs in cancer therapies, while also discussing several current challenges and needed future research.

Aberrant MicroRNAs in Pancreatic Cancer: Researches and Clinical Implications

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

MicroRNA profiling implies new markers of chemoresistance of triple-negative breast cancer

Objective

Triple-negative breast cancer (TNBC) patients with truly chemosensitive disease still represent a minority among all TNBC patients. The aim of the present study is to identify microRNAs (miRNAs) that correlate with TNBC chemoresistance.

Methods

In this study, we conducted miRNAs profile comparison between triple-negative breast cancer (TNBCs) and normal breast tissues by microRNA array. Quantitative real-time PCR (qRT-PCR) was utilized to confirm the specific deregulated miRNAs change trend. We used starBase 2.1 and GOrilla to predict the potential targets of the specific miRNAs. Cells viability and apoptosis assays were employed to determine the effect of alteration of the specific miRNAs in TNBC cells on the chemosensitivity.

Results

We identified 11 specific deregulated miRNAs, including 5 up-regulated miRNAs (miR-155-5p, miR-21-3p, miR-181a-5p, miR-181b-5p, and miR-183-5p) and 6 down-regulated miRNAs (miR-10b-5p, miR-451a, miR-125b-5p, miR-31-5p, miR-195-5p and miR-130a-3p). Thereafter, this result was confirmed by qRT-PCR. We predicted the potential targets of the candidate miRNAs and found that they are involved in cancer-associated pathways. For the first time, we found that miR-130a-3p and miR-451a were down-regulated in TNBC. 9 of the 11 specific deregulated miRNAs were found to be associated with chemoresistance. In vitro assays, we found that up-regulation of either miR-130a-3p or miR-451a in MDA-MB-231 cells significantly changed the cells sensitivity to doxorubicin. The results suggest that TNBC chemotherapy might be affected by a cluster of miRNAs.

Conclusion

The abnormal expression miRNAs in TNBC are mainly chemoresistance related. This might be part of reason that TNBC likely to evade from chemotherapy resulting in early relapse and high risk of death. To alter their expression status might be a potential therapeutic strategy to improve the outcome of chemotherapy for TNBC patients.

Anandamide attenuates Th-17 cell-mediated delayed-type hypersensitivity response by triggering IL-10 production and consequent microRNA induction

Endogenous cannabinoids [endocannabinoids] are lipid signaling molecules that have been shown to modulate immune functions. However, their role in the regulation of Th17 cells has not been studied previously. In the current study, we used methylated Bovine Serum Albumin [mBSA]-induced delayed type hypersensitivity [DTH] response in C57BL/6 mice, mediated by Th17 cells, as a model to test the anti-inflammatory effects of endocannabinoids. Administration of anandamide [AEA], a member of the endocannabinoid family, into mice resulted in significant mitigation of mBSA-induced inflammation, including foot pad swelling, cell infiltration, and cell proliferation in the draining lymph nodes [LN]. AEA treatment significantly reduced IL-17 and IFN-γ production, as well as decreased RORγt expression while causing significant induction of IL-10 in the draining LNs. IL-10 was critical for the AEA-induced mitigation of DTH response inasmuch as neutralization of IL-10 reversed the effects of AEA. We next analyzed miRNA from the LN cells and found that 100 out of 609 miRNA species were differentially regulated in AEA-treated mice when compared to controls. Several of these miRNAs targeted proinflammatory mediators. Interestingly, many of these miRNA were also upregulated upon in vitro treatment of LN cells with IL-10. Together, the current study demonstrates that AEA may suppress Th-17 cell–mediated DTH response by inducing IL-10 which in turn triggers miRNA that target proinflammatory pathways.

miR-181 subunits enhance the chemosensitivity of temozolomide by Rap1B-mediated cytoskeleton remodeling in glioblastoma cells

Glioblastoma multiforme (GBM) is the most malignant and frequent brain tumor, with an aggressive growth pattern and poor prognosis despite best treatment modalities. Although chemotherapy with temozolomide (TMZ) may restrain tumor growth for some months, TMZ resistance is also common and accounts for many treatment failures. Research into microRNA's role in GBM has shown that microRNAs play a key regulatory role in the GBM, making it a potential therapeutic target. In this study, we demonstrated that the lower expression of miR-181a/b/c/d subunits contributes to astrocytoma tumorigenesis, and their overexpression could inhibit the invasive proliferation of glioblastoma cells by targeting Rap1B-mediated cytoskeleton remodeling and related molecular (Cdc42, RhoA and N-cadherin) changes, suggesting that miR-181 was a critical regulator and might be an important target for glioblastoma treatment. TMZ as a standard chemotherapeutic agent for GBM inhibited the Rap1B expression and actin cytoskeleton remodeling to exert its cell killing by upregulating miR-181a/b/c/d subunits; conversely, each miR-181a/b/c/d subunit enhanced the chemosensitivity of TMZ in glioblastoma cells.

Prospects of miRNA-based therapy for pancreatic cancer

Pancreatic cancer (PC) is the fourth leading cause of cancer related deaths in the U.S., with a less than 6% five-year survival rate. Treatment is confounded by advanced stage of disease at presentation, frequent metastasis to distant organs at the time of diagnosis and resistance to conventional chemotherapy. In addition, the molecular pathogenesis of the disease is unclear. The extensive study of miRNAs over the past several years has revealed that miRNAs are frequently de-regulated in pancreatic cancer and contribute to the pathogenesis and aggressiveness of the disease. Several studies have tackled the practical difficulties in the application of miRNAs as viable therapeutic and diagnostic tools. Given that a single miRNA can affect a myriad of cellular processes, successful targeting of miRNAs as therapeutic agents could likely yield dramatic results. The current review attempts to summarize the advances in the field and assesses the prospects for miRNA profiling and targeting in aiding PC treatment.

miR-181b promotes cell proliferation and reduces apoptosis by repressing the expression of adenylyl cyclase 9 (AC9) in cervical cancer cells

MicroRNAs are a class of small, endogenous, non-coding RNAs that function as post-transcriptional regulators. In this study, we found that miR-181b promoted cell proliferation and inhibited cell apoptosis in cervical cancer cells. And we validated a new miR-181b target gene, adenylyl cyclase 9 (AC9). miR-181b restricted cAMP production by post-transcriptionally downregulating AC9 expression. Phenotypic experiments indicated that miR-181b and AC9 exerted opposite effects on cell proliferation and apoptosis.

Involvement of microRNA-181b in the gemcitabine resistance of pancreatic cancer cells

BACKGROUND/OBJECTIVES

MicroRNAs (miRs) have been shown to regulate the sensitivity to several chemotherapeutic agents in various types of cancers. MiR-181b is one of such regulators, yet its importance in pancreatic cancer is not determined so far. The aim of this study was to investigate the relationship between microRNA (miR)-181b expression and gemcitabine resistance in pancreatic cancer cells.

METHODS

The effects of overexpression or knockdown of miR-181b on four pancreatic cancer cell lines exposed to gemcitabine were examined. The induction of apoptosis and the changes of the cylindromatosis (CYLD) protein were examined. Furthermore, the effect of small interference RNA for CYLD (siCYLD) on cell viability and the relationship between CYLD and nuclear factor kappa B (NF-κB) were investigated.

RESULTS

The expression of miR-181b was higher in BxPC3, Panc1 and PSN1 cells compared with MiaPaCa2 cells. Pre-miR-181b transfection into MiaPaCa2 cells increased their gemcitabine resistance, whereas anti-miR-181b transfection into the other pancreatic cancer cell lines reduced their resistance to gemcitabine and led to the induction of apoptosis. The protein levels of CYLD were increased by anti-miR-181b in Panc1 and PSN1 cells. Inhibition of CYLD increased the NF-κB activity and gemcitabine resistance in Panc1 and PSN1 cells.

CONCLUSIONS

The present study demonstrated that miR-181b was associated with the resistance of pancreatic cancer cells to gemcitabine, and verified that miR-181b enhances the activity of NF-κB by inhibiting CYLD, leading to the resistance to gemcitabine. Our results suggest that miR-181b is a potential target for decreasing gemcitabine resistance.