Migration Of Pancreatic Ductal Adenocarcinoma Cells Research Articles

Rosmarinic Acid Decreases the Malignancy of Pancreatic Cancer Through Inhibiting Gli1 Signaling

BackgroundRosmarinic acid (RA) has been shown to exert anti-tumor effects on various types of cancer. However, its roles in the treatment of pancreatic ductal adenocarcinoma (PDAC) and the underlying mechanisms remain elusive. PurposeThe present study aimed to investigate the therapeutic effects of RA on PDAC as well as the underlying mechanisms. Study designEvaluation of the effects of RA on PDAC malignancy both in vitro and in vivo. MethodsCell counting kit 8 (CCK8) assay, colony formation assay, 5-Ethynyl-2′-deoxyuridine (EDU) incorporation assay, cell cycle analysis, and apoptosis assay were conducted to assess the inhibitory effect of RA on PDAC cell proliferation. Meanwhile, western blotting and RT-qPCR assay were performed to detect the target gene expression at protein and mRNA levels, respectively. Moreover, the in vivo anti-tumor activities of RA were assayed in an xenograft mouse model of PDAC. ResultsRA dramatically down-regulated Gli1 and its downstream targets. Further studies showed that RA prevents the nuclear translocation of Gli1, while promoting the degradation of cytosolic Gli1 via the proteasome pathway. Moreover, we observed that RA induced G1/S cell cycle arrest and apoptosis in the PDAC cells through regulating the expression of P21, P27, CDK2, Cyclin E, Bax, and Bcl-2, it inhibited the PDAC cell migration and invasion via E-cadherin and MMP-9. Notably, Gli1 overexpression markedly reversed the above RA-induced effects on PDAC cells, whereas Gli1 knockdown enhanced the effects. Additionally, the in vivo assays demonstrated that RA suppresses the tumor growth of PDAC presumably by inhibiting Gli1. ConclusionWe provided evidence that RA restrained the nuclear translocation of Gli1 and facilitates Gli1 degradation via proteasome pathway, reducing the malignancy of PDAC cells. These findings implicated RA as a therapeutic agent for PDAC.

NR2F1-AS1 Promotes Pancreatic Ductal Adenocarcinoma Progression Through Competing Endogenous RNA Regulatory Network Constructed by Sponging miRNA-146a-5p/miRNA-877-5p.

The role of NR2F1-AS1 in pancreatic ductal adenocarcinoma (PDAC) remains unknown. Therefore, we aimed to investigate the biological mechanism of NR2F1-AS1 in PDAC. The expression of NR2F1-AS1 was measured by using microarray data and real-time PCR. The effects of NR2F1-AS1 knockdown on proliferation, cell cycle progression, invasion in vitro and tumorigenesis in vivo were investigated. The mechanism of competitive endogenous RNAs was determined from bioinformatics analyses and validated by a dual-luciferase reporter gene assay. Potential target mRNAs from TargetScan 7.2 were selected for subsequent bioinformatics analysis. Key target mRNAs were further identified by screening hub genes and coexpressed protein-coding genes (CEGs) of NR2F1-AS1. NR2F1-AS1 was highly expressed in PDAC, and the overexpression of NR2F1-AS1 was associated with overall survival and disease-free survival. The knockdown of NR2F1-AS1 impaired PDAC cell proliferation, migration, invasion and tumorigenesis. NR2F1-AS1 competitively sponged miR-146a-5p and miR-877-5p, and low expression of the two miRNAs was associated with a poor prognosis. An integrative expression and survival analysis of the hub genes and CEGs demonstrated that the NR2F1-AS1–miR-146a-5p/miR-877-5p–GALNT10/ZNF532/SLC39A1/PGK1/LCO3A1/NRP2/LPCAT2/PSMA4 and CLTC ceRNA networks were linked to the prognosis of PDAC. In conclusion, NR2F1-AS1 overexpression was significantly associated with poor prognosis. NR2F1-AS1 functions as an endogenous RNA to construct a novel ceRNA network by competitively binding to miR-146a-5p/miR-877-5p, which may contribute to PDAC pathogenesis and could represent a promising diagnostic biomarker or potential novel therapeutic target in PDAC.

KDM6A Regulates Cell Plasticity and Pancreatic Cancer Progression by Noncanonical Activin Pathway.

Background & AimsInactivating mutations of KDM6A, a histone demethylase, were frequently found in pancreatic ductal adenocarcinoma (PDAC). We investigated the role of KDM6A (lysine demethylase 6A) in PDAC development.MethodsWe performed a pancreatic tissue microarray analysis of KDM6A protein levels. We used human PDAC cell lines for KDM6A knockout and knockdown experiments. We performed bromouridine sequencing analysis to elucidate the effects of KDM6A loss on global transcription. We performed studies with Ptf1aCre; LSL-KrasG12D; Trp53R172H/+; Kdm6afl/fl or fl/Y, Ptf1aCre; Kdm6afl/fl or fl/Y, and orthotopic xenograft mice to investigate the impacts of Kdm6a deficiency on pancreatic tumorigenesis and pancreatitis.ResultsLoss of KDM6A was associated with metastasis in PDAC patients. Bromouridine sequencing analysis showed up-regulation of the epithelial–mesenchymal transition pathway in PDAC cells deficient in KDM6A. Loss of KDM6A promoted mesenchymal morphology, migration, and invasion in PDAC cells in vitro. Mechanistically, activin A and subsequent p38 activation likely mediated the role of KDM6A loss. Inhibiting either activin A or p38 reversed the effect. Pancreas-specific Kdm6a-knockout mice pancreata showed accelerated PDAC progression, developed a more aggressive undifferentiated type of PDAC, and increased metastases in the background of Kras and p53 mutations. Kdm6a-deficient pancreata in a pancreatitis model had a delayed recovery with increased PDAC precursor lesions compared with wild-type pancreata.ConclusionsLoss of KDM6A accelerates PDAC progression and metastasis, most likely by a noncanonical p38-dependent activin A pathway. KDM6A also promotes pancreatic tissue recovery from pancreatitis. Activin A might be used as a therapeutic target for KDM6A-deficient PDACs.

The long non-coding RNA DKFZp434J0226 regulates the alternative splicing process through phosphorylation of SF3B6 in PDAC

BackgroundLong noncoding RNAs (lncRNAs), a type of pervasive genes that regulates various biological processes, are differentially expressed in different types of malignant tumors. The role of lncRNAs in the carcinogenesis of pancreatic ductal adenocarcinoma (PDAC) remains unclear. Here, we investigated the role of the lncRNA DKFZp434J0226 in PDAC.MethodsAberrantly expressed mRNAs and lncRNAs among six PDAC and paired non-tumorous tissues were profiled using microarray analysis. Quantitative real-time polymerase chain reaction was used to evaluate DKFZp434J0226 expression in PDAC tissues. CCK-8 assay, wound-healing assay, soft agar colony formation assay, and transwell assay were performed to assess the invasiveness and proliferation of PDAC cells. Furthermore, RNA pull-down, immunofluorescence, RNA immunoprecipitation, and western blotting assays were performed to investigate the association between DKFZp434J0226 and SF3B6. Tumor xenografts in mice were used to test for tumor formation in vivo.ResultsIn our study, 222 mRNAs and 128 lncRNAs were aberrantly expressed (≥ twofold change). Of these, 66 mRNAs and 53 lncRNAs were upregulated, while 75 lncRNAs and 156 mRNAs were downregulated. KEGG pathway analysis and the Gene ontology category indicated that these genes were associated with the regulation of mRNA alternative splicing and metabolic balance. Clinical analyses revealed that overexpression of DKFZp434J0226 was associated with worse tumor grading, frequent perineural invasion, advanced tumor-node-metastasis stage, and decreased overall survival and time to progression. Functional assays demonstrated that DKFZp434J0226 promoted PDAC cell migration, invasion, and growth in vitro and accelerated tumor proliferation in vivo. Mechanistically, DKFZp434J0226 interacted with the splicing factor SF3B6 and promoted its phosphorylation, which further regulated the alternative splicing of pre-mRNA.ConclusionsThis study indicates that DKFZp434J0226 regulates alternative splicing through phosphorylation of SF3B6 in PDAC and leads to an oncogenic phenotype in PDAC.

ELK3 Mediated by ZEB1 Facilitates the Growth and Metastasis of Pancreatic Carcinoma by Activating the Wnt/β-Catenin Pathway.

Rapid progression and metastasis are the major causes of death in patients with pancreatic ductal adenocarcinoma (PDAC). ELK3, a member of the ternary complex factor (TCF), has been associated with the initiation and progression of various cancers. However, the role of ELK3 in PDAC is not yet fully understood. Online databases and immunohistochemistry were used to analyze the ELK3 levels in PDAC tissues. The function of ELK3 was confirmed by a series of in vivo and in vitro studies. Western blotting and immunofluorescence were used to detect the molecular mechanisms of PDAC. ChIP-qPCR was used to study the mechanism responsible for the elevation of ELK3 expression in PDAC. The ELK3 levels were higher in PDAC tissues than in adjacent normal tissues. Functionally, we demonstrated that ELK3 acted as an oncogene to promote PDAC tumorigenesis and metastasis. Further study suggested that ELK3 promoted PDAC cell migration and invasion by activating the Wnt/β-catenin pathway, and proved that ZEB1 could directly bind to the promoter of ELK3 to increase its transcription. Finally, both were associated with the patients’ clinicopathological features and worse overall survival. Conclusively, our findings enrich the role of ELK3 in PDAC, and provide potential avenues for exploring more effective biomarkers and therapeutic strategies for the treatment of PDAC.

Downregulated expression of IL‑28RA is involved in the pathogenesis of pancreatic ductal adenocarcinoma.

Pancreatic cancer ranks seventh in terms of cancer‑related mortality in men and women worldwide, where the most common subtype is pancreatic ductal adenocarcinoma (PDAC). To date, the pathogenesis of PDAC remains incompletely understood and the prognosis of PDAC is poor. In the present study, the expression of interleukin‑28 receptorα subunit (IL‑28RA) in PDAC tissues was detected using immunofluorescence staining and western blotting. IL‑28RA recombinant plasmids and control pCMV6‑entrymammalian expression plasmid, short hairpin (sh)IL‑28RA plasmids and control pRS scrambled shRNA vector purchased were used to produce stably transfected PANC‑1 cells overexpressing IL‑28RA or with IL‑28RA expression knocked down. MTS assays were used to measure cell viability and wound healing assay was used to assess the cell migratory ability invitro. Flow cytometry analysis was performed to determine the proportion of cells in each phase of the cell cycle whereas total protein and phosphorylated protein levels were assessed using western blotting. Xenograft models of subcutaneous tumors were established by injecting PANC‑1 cells hypodermically into nude mice to investigate the effect of IL‑28RA on tumorigenesis and tumor growth. The results showed that the expression of IL‑28RA in PDAC tissues was lower compared with that in normal tissues. IL‑28RA overexpression invitro resulted in the activation of the IL‑28RA pathway, which reduced cell viability and decreased the proportion of cells in the G2/M phase by reducing cyclin B1 expression. In addition, IL‑28RA overexpression inhibited migration of PDAC cells. By contrast, an increased proportion of cells in G2/M phase, upregulated cyclin B1 expression and enhanced cell viability and migratory ability along with inhibition of the IL‑28RA pathway were observed in PANC‑1 cells following IL‑28RA knockdown. The inhibitory effect of IL‑28RA was observed by tumor size in a nude mouse model induced by PANC‑1 cells with stable IL‑28RA overexpression or knockdown. The tumor size induced by PANC‑1 cells with stable IL‑28RA overexpression were smaller, whilst larger tumors induced by PANC‑1 cells were observed following stable IL‑28RA knockdown, when compared to control. Further studies showed that the effect of IL‑28RA on PDAC cells was exerted by regulating the phosphorylation levels of STAT1 and AKT. In conclusion, lower IL‑28RA expression may contribute to the pathogenesis of PDAC, where results from the present may provide further insights into the progression of PDAC, in addition to highlighting potentially novel therapeutic targets for this disease.

ROBO2 hampers malignant biological behavior and predicts a better prognosis in pancreatic adenocarcinoma

Background Pancreatic ductal adenocarcinoma (PDAC) is a fatalmalignant cancer with extremely poor prognosis and high mortality. Genome wide studies show that Slit/Robo signaling pathway takes a major effect in the oncogenesis and progression of pancreatic cancer. However, the function and mechanism of ROBO2 in the development of PDAC remains unclear. Methods In present study, we use Western blot and real-time polymerase chain reaction (RT-PCR) to detect the expression of ROBO2 in pancreatic cell lines. Cell proliferation,Transwellmigration and invasion were conducted inAsPC-1, MIA PaCa-2 and PANC-1cell lines. RNA sequencing, bioinformatics analysisand Western blot were used to explore its mechanism and potential target molecules. The expression of ROBO2 in 95 tumor tissues was detected by immunohistochemistry. Results ROBO2 expression was downregulated in PDAC cell lines and tissue samples. A high expression of ROBO2 was associated with better prognosis. Upregulation of ROBO2 inhibited PDAC cell proliferation, migration, and invasion. However, we found theoppositeresults in the ROBO2 downregulation group. In addition, the function of ROBO2 on cell proliferation was further affirmed by the animal model. Finally, the results of RNA sequencing indicated that ROBO2 partly promoted the antitumor activity by inhibiting ECM1 in PDAC. Conclusions Our work suggests that ROBO2 inhibits tumor progression in PDAC and may serve as a predictive biomarker and therapeutic target in PDAC.

CDK5 positively regulates Notch1 signaling in pancreatic cancer cells by phosphorylation.

The marked overexpression of cyclin‐dependent kinase 5 (CDK5) or Notch1 receptor, which plays critical roles in pancreatic ductal adenocarcinoma (PDAC) development, has been detected in numerous PDAC cell lines and tissues. Although, a previous study has demonstrated that CDK5 inhibition disrupts Notch1 functions in human umbilical vein endothelial cells, the mechanism underlying Notch1 activation regulated by CDK5 remains unclear. Herein, we identified a physical interaction between CDK5 and Notch1 in PDAC cells, with the Notch1 peptide phosphorylated by CDK5/p25 kinase. CDK5 blockade resulted in the profound inhibition of Notch signaling. Accordingly, CDK5 inhibition sensitized PDAC cell proliferation and migration following Notch inhibition. In conclusion, CDK5 positively regulates Notch1 function via phosphorylation, which in turn promotes cell proliferation and migration. The combinational inhibition of CDK5 and Notch signaling may be an effective strategy in the treatment of PDAC.

Recent, Bioelectricity-Related Articles Selected by Ann M. Rajnicek, Media Editor of Bioelectricity.

Recent, Bioelectricity-Related Articles Selected by Ann M. Rajnicek, Media Editor of Bioelectricity.

Betulinic Acid Affects the Energy-Related Proteomic Profiling in Pancreatic Ductal Adenocarcinoma Cells.

Pancreatic ductal adenocarcinoma (PDAC) is an aggressive disease with a 5-year survival rate of <8%. Therefore, finding new treatment strategies against PDAC cells is an imperative issue. Betulinic acid (BA), a plant-derived natural compound, has shown great potential to combat cancer owing to its versatile physiological functions. In this study, we observed the impacts of BA on the cell viability and migratory ability of PDAC cell lines, and screened differentially expressed proteins (DEPs) by an LC-MS/MS-based proteomics analysis. Our results showed that BA significantly inhibited the viability and migratory ability of PDAC cells under a relatively low dosage without affecting normal pancreatic cells. Moreover, a functional analysis revealed that BA-induced downregulation of protein clusters that participate in mitochondrial complex 1 activity and oxidative phosphorylation, which was related to decreased expressions of RNA polymerase mitochondrial (POLRMT) and translational activator of cytochrome c oxidase (TACO1), suggesting that the influence on mitochondrial function explains the effect of BA on PDAC cell growth and migration. In addition, BA also dramatically increased Apolipoprotein A1 (APOA1) expression and decreased NLR family CARD domain-containing protein 4 (NLRC4) expression, which may be involved in the dampening of PDAC migration. Notably, altered expression patterns of APOA1 and NLRC4 indicated a favorable clinical prognosis of PDAC. Based on these findings, we identified potential proteins and pathways regulated by BA from a proteomics perspective, which provides a therapeutic window for PDAC.

Role of stromal activin A in human pancreatic cancer and metastasis in mice

Pancreatic ductal adenocarcinoma (PDAC) has extensive stromal involvement and remains one of the cancers with the highest mortality rates. Activin A has been implicated in colon cancer and its stroma but its role in the stroma of PDAC has not been elucidated. Activin A expression in cancer and stroma was assessed in human PDAC tissue microarrays (TMA). Activin A expression in human TMA is significantly higher in cancer samples, with expression in stroma correlated with shorter survival. Cultured pancreatic stellate cells (PSC) were found to secrete high levels of activin A resulting in PDAC cell migration that is abolished by anti-activin A neutralizing antibody. KPC mice treated with anti-activin A neutralizing antibody were evaluated for tumors, lesions and metastases quantified by immunohistochemistry. KPC mice with increased tumor burden express high plasma activin A. Treating KPC mice with an activin A neutralizing antibody does not reduce primary tumor size but decreases tumor metastases. From these data we conclude that PDAC patients with high activin A expression in stroma have a worse prognosis. PSCs secrete activin A, promoting increased PDAC migration. Inhibition of activin A in mice decreased metastases. Hence, stroma-rich PDAC patients might benefit from activin A inhibition.

Hydrogel Models with Stiffness Gradients for Interrogating Pancreatic Cancer Cell Fate.

Pancreatic ductal adenocarcinoma (PDAC) is the most common type of pancreatic cancer and has seen only modest improvements in patient survival rate over the past few decades. PDAC is highly aggressive and resistant to chemotherapy, owing to the presence of a dense and hypovascularized fibrotic tissue, which is composed of stromal cells and extracellular matrices. Increase deposition and crosslinking of matrices by stromal cells lead to a heterogeneous microenvironment that aids in PDAC development. In the past decade, various hydrogel-based, in vitro tumor models have been developed to mimic and recapitulate aspects of the tumor microenvironment in PDAC. Advances in hydrogel chemistry and engineering should provide a venue for discovering new insights regarding how matrix properties govern PDAC cell growth, migration, invasion, and drug resistance. These engineered hydrogels are ideal for understanding how variation in matrix properties contributes to the progressiveness of cancer cells, including durotaxis, the directional migration of cells in response to a stiffness gradient. This review surveys the various hydrogel-based, in vitro tumor models and the methods to generate gradient stiffness for studying migration and other cancer cell fate processes in PDAC.

Pancreatic stellate cells regulate branched-chain amino acid metabolism in pancreatic cancer

BackgroundPancreatic ductal adenocarcinoma (PDAC) is the most lethal malignancy: it has a 5-year survival rate of less than 9%. Although surgical resection is an effective treatment for PDAC, only a small number of patients can have their tumors surgically removed. Thus, an urgent need to find new therapeutic targets for PDAC exists. Understanding the molecular mechanism of PDAC development is essential for the treatment of this malignancy. This research aimed to study the mechanisms of pancreatic stellate cells (PSCs), which regulate branched-chain amino acid (BCAA) metabolism in PDAC.MethodsDifferentially expressed proteins were detected via nanoliquid chromatography coupled to mass spectrometry (nano-LC-MS/MS). Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway enrichment methods were used to find the valine-leucine-isoleucine (BCAA) degradation pathway. The levels of BCAAs in the sera and tissues of patients with PDAC were measured by using nuclear magnetic resonance (NMR). The functions of BCAA concentrations and the effects of activated pancreatic stellate cells (aPSCs) were also evaluated by performing Cell Counting Kit-8, colony formation, and wound healing assays.ResultsA total of 1,519 proteins with significantly differential expression were discovered in PDAC and adjacent tissues by using nano-LC-MS/MS. KEGG pathway enrichment analysis identified the BCAA degradation pathway. The content of BCAA in PDAC clinical samples was up-regulated. However, the addition of different concentrations of BCAA to PDAC cell culture medium failed to promote the proliferation and migration of PDAC cells. Given that analysis based on The Cancer Genome Atlas database showed that the number of aPSCs gradually increased with the progression of PDAC, the effects of aPSCs on PDAC cells were explored. After coculture with aPSCs, PDAC cell proliferation showed a significant increase, and the proteins involved in the BCAA degradation pathway in PDAC cells had also changed.ConclusionsaPSCs could regulate BCAA metabolism to enhance the progression of PDAC, indicating that the regulation of BCAA metabolism may serve as a new therapeutic direction for PDAC.

Four potential microRNAs affect the progression of pancreatic ductal adenocarcinoma by targeting MET via the PI3K/AKT signaling pathway.

Pancreatic ductal adenocarcinoma (PDAC) is the most common tumor subtype of pancreatic cancer, which exhibits poor patient prognosis due to the lack of effective biomarkers in the diagnosis and treatment. The present study aimed to identify the potential biomarkers of PDAC carcinogenesis and progression using three microarray datasets, GSE15471, GSE16515 and GSE28735, which were downloaded from the Gene Expression Omnibus database. The datasets were analyzed to screen out differentially expressed genes (DEGs) in PDAC tissues and adjacent normal tissues. A total of 143 DEGs were identified, including 132 upregulated genes and 11 downregulated genes. Gene Ontology and Kyoto Encyclopedia of Genes and Genomes functional and signaling pathway enrichment analyses were performed on the DEGs, and the Search Tool for the Retrieval of Interacting Genes/Proteins database was used to construct a protein-protein interaction network. The main functions of DEGs include extracellular matrix degradation, and regulation of matrix metalloproteinase activity and the PI3K-Akt signaling pathway. The five hub genes were subsequently screened using Cytoscape software, and survival analysis demonstrated that abnormal expression levels of the hub genes was associated with poor disease-free survival and overall survival. Biological experiments were performed to confirm whether mesenchymal-to-epithelial transition (MET) factors promote the proliferation, migration and invasion of PDAC cells via the PI3K/AKT signaling pathway. In addition, six MET-targeted microRNAs (miRNAs) were identified, four of which had conserved binding sites with MET. Based on the signaling pathway enrichment analysis of these miRNAs, it is suggested that they can affect the progression of PDAC by targeting MET via the PI3K/AKT signaling pathway. In conclusion, the hub genes and miRNAs that were identified in the present study contribute to the molecular mechanisms of PDAC carcinogenesis and progression. They also provide candidate biomarkers for early diagnosis and treatment of patients with PDAC.

KLHDC7B-DT aggravates pancreatic ductal adenocarcinoma development via inducing cross-talk between cancer cells and macrophages.

Tumor microenvironment (TME) exerts key roles in pancreatic ductal adenocarcinoma (PDAC) development. However, the factors regulating the cross-talk between PDAC cells and TME are largely unknown. In the present study, we identified a long noncoding RNA (lncRNA) KLHDC7B divergent transcript (KLHDC7B-DT), which was up-regulated in PDAC and correlated with poor survival of PDAC patients. Functional assays demonstrated that KLHDC7B-DT enhanced PDAC cell proliferation, migration, and invasion. Mechanistically, KLHDC7B-DT was found to directly bind IL-6 promoter, induce open chromatin structure at IL-6 promoter region, activate IL-6 transcription, and up-regulate IL-6 expression and secretion. The expression of KLHDC7B-DT was positively correlated with IL-6 in PDAC tissues. Via inducing IL-6 secretion, KLHDC7B-DT activated STAT3 signaling in PDAC cells in an autocrine manner. Furthermore, KLHDC7B-DT also activated STAT3 signaling in macrophages in a paracrine manner, which induced macrophage M2 polarization. KLHDC7B-DT overexpressed PDAC cells-primed macrophages promoted PDAC cell proliferation, migration, and invasion. Blocking IL-6/STAT3 signaling reversed the effects of KLHDC7B-DT on macrophage M2 polarization and PDAC cell proliferation, migration, and invasion. In conclusion, KLHDC7B-DT enhanced malignant behaviors of PDAC cells via IL-6-induced macrophage M2 polarization and IL-6-activated STAT3 signaling in PDAC cells. The cross-talk between PDAC cells and macrophages induced by KLHDC7B-DT represents potential therapeutic target for PDAC.

Crosstalk between Macrophages and Endothelial Cells in the Tumor Microenvironment

Crosstalk between Macrophages and Endothelial Cells in the Tumor Microenvironment

PALB2 upregulation is associated with a poor prognosis in pancreatic ductal adenocarcinoma.

During DNA repair, BRCA1 and BRCA2 interact with the tumor suppressor partner and localizer of BRCA2 (PALB2). PALB2 mutations are associated with an increased risk of breast and ovarian carcinoma, and upregulated PALB2 expression is associated with poor clinical outcomes. The present study investigated the role and prognostic value of PALB2 in pancreatic ductal adenocarcinoma (PDAC). PALB2 expression was inhibited using a small interfering RNA in PDAC cell lines, and the subsequent effects on cell proliferation and migration were investigated. Tissue microarrays from 157 patients undergoing a pancreaticoduodenectomy for PDAC were analyzed via immunohistochemistry, and PALB2 expression was compared with patient outcomes using Kaplan-Meier curves and the multivariate Cox regression model. PALB2-knockdown in PDAC cells had little effect on cell proliferation, but significantly decreased cell migration. Relatively high PALB2 expression was observed in PDAC tissues compared with in peritumoral tissues. Overall survival (OS) was negatively associated with PALB2 expression. TNM stage and PALB2 expression were identified as independent prognostic factors associated with OS via multivariate analysis. Overall, the present study demonstrated that PDAC cell migration was dependent on PALB2, which was further supported by the finding that elevated PALB2 expression in PDAC tissues was associated with poor survival in patients with PDAC. Therefore, PALB2 may serve as a novel prognostic marker in PDAC, which may aid with the development of therapeutic strategies for the disease.

Repression of circRNA_000684 inhibits malignant phenotypes of pancreatic ductal adenocarcinoma cells via miR-145-mediated KLF5

BackgroundCircular RNAs (circRNAs) are aberrantly expressed in pancreatic ductal adenocarcinoma (PDAC). In the current study, we investigated how circRNA_000684 affected the progression of PDAC, and how it regulated kruppel-like factor 5 (KLF5) and microRNA (miR)-145. MethodsDifferentially expressed circRNAs, miRs and genes related to PDAC as well as their targeting relationship were predicted using bioinformatics analyses. Binding relationships among circRNA_000684, miR-145 and KLF5 were verified using dual-luciferase reporter gene assay, RIP and RNA pull-down assay, respectively. The effects of circRNA_000684, miR-145, KLF5 on the malignant phenotypes of PDAC cells and human umbilical vein endothelial cell (HUVEC) angiogenesis were assessed using loss- and gain-of function experiments by CCK-8 assay, scratch test, Transwell and tube formation assays. RT-qPCR and Western blot analysis were used to determine MCM2, MMP2 and MMP9 and VEGFA expression. In addition, the roles of circRNA_000684, miR-145, and KLF5 in tumor growth were validated through in vivo experiments. ResultsExpression of CircRNA_000684 and KLF5 was upregulated, whereas miR-145 expression was downregulated in PDAC tissues and cells. CircRNA_000684 repression or miR-145 elevation inhibited the proliferation, invasion and migration of PDAC cells and HUVEC angiogenesis, as evidenced by lower levels of MCM2, MMP2 and MMP9 and VEGFA. CircRNA_000684 negatively regulated miR-145 expression, while miR-145 negatively regulated KLF5. In-vivo, circRNA_000684 elevation or miR-145 repression promoted tumor growth. ConclusionTaken together, the present study provided evidence clarifying that circRNA_000684 could downregulate miR-145 expression and elevate KLF5 to promote the progression of PDAC.

Ubiquitin-specific protease 14 (USP14) promotes proliferation and metastasis in pancreatic ductal adenocarcinoma.

Previous studies have shown aberrant expression of ubiquitin-specific protease 14 (USP14) in multiple malignancies, suggesting an important role of USP14 in tumorigenesis. However, the functional role of USP14 in pancreatic ductal adenocarcinoma (PDAC) has never been elucidated. In this study, we found that USP14 was remarkably upregulated in PDAC tissues compared with normal pancreatic tissues. Notably, Kaplan-Meier curves showed that high expression of USP14 predicted significantly worse prognosis in PDAC patients than low expression of USP14. To determine whether USP14 could regulate the proliferation, apoptosis and metastasis of PDAC cells, we knocked down endogenous USP14 or overexpressed exogenous USP14 in Panc-1 and BxPC-3 cells. Using MTT assays, colony formation analyses, flow cytometry assays, and cell invasion and migration assays, we found that knockdown of USP14 attenuated proliferation, induced apoptosis and restrained invasion and migration of PDAC cells. Overexpression of USP14 could enhance proliferation, prevent apoptosis and promote invasion and migration of PDAC cells. In addition, USP14 could regulate the expression of cyclin D1, PCNA and E-cadherin, three important carcinogenic factors, in PDAC cells. These findings suggest that USP14 might play an important role in promoting the tumorigenesis of PDAC and thus be a promising therapeutic target to prevent PDAC progression.

CircFOXK2 Promotes Tumor Growth and Metastasis of Pancreatic Ductal Adenocarcinoma via Complexing with RNA Binding Proteins and Sponging MiR-942

Abstract Objective Circular RNA (circRNA) is a novel class of non-coding RNAs that regulate gene expression. However, the role of circRNAs in pancreatic ductal adenocarcinoma (PDAC) is largely unknown. Design We performed circRNA sequencing of non-tumor HPDE and PDAC cells. We investigated the functions of circFOXK2 in PDAC by gain-of-function and loss-of-function assays. Bioinformatics analysis, luciferase assay and microRNA pulldown assays were performed to identify circFOXK2 interacting-miRNAs. To further investigate the mechanism, we performed circRNA-pulldown and mass spectrometry to identify circFOXK2-interacting proteins in PDAC. Results We identified 169 differentially expressed circRNAs in PDAC cells. We validated that one of the circRNAs circFOXK2 was significantly up-regulated in PDAC cells and in 63 % of primary tumor (53 out of 84). Gain-of-function and loss-of-function assays demonstrated that circFOXK2 promoted PDAC cell growth, migration and invasion. CircFOXK2 was also involved in cell cycle progression and apoptosis. circFOXK2 functioned as sponge for miR-942, and in turn promoted the expression of miR-942 targets ANK1, GDNF and PAX6. Furthermore, circFOXK2 interacted with 94 proteins, which were involved in cell adhesion and mRNA splicing. Among these circFOXK2-interacting proteins, YBX1 and hnRNPK were validated by RNA immunoprecipitation. Importantly, circFOKX2 interacted with YBX1 and hnRNPK targets NUF2 and PDXK in PDAC cells. Knockdown of circFOXK2 reduced the binding of YBX1 and hnRNPK to NUF2 and PDXK, and in turn decreased their expressions in PDAC cells. Conclusion We identified that circFOXK2 promoted PDAC cells growth and metastasis. Also, circFOXK2 complexed with YBX1 and hnRNPK to promote the expressions of oncogenic proteins. Significance of this study What is already known on this subject? Differentially expressed circRNAs are involved in carcinogenesis of many cancers. CircRNAs function as microRNA sponges to regulate gene expression. The roles of circRNAs in PDAC progression is largely unknown. What are the new findings? circFOXK2 is upregulated in PDAC primary tumors. circFOXK2 promotes PDAC tumor growth and liver metastasis. circFOXK2 functions as sponges for miR-942 to promote the expressions of oncogenic ANK1, GDNF and PAX6. circFOXK2 complexes with YBX1 and hnRNPK to promote the expressions of oncogenic proteins in PDAC. How might it impact on clinical practice in the foreseeable future? circFOXK2 upregulation in PDAC may function as a novel biomarker for diagnosis. circFOXK2 may be a novel therapeutic target in treating PDAC.