Epithelial-mesenchymal Transition In Pancreatic Cancer Research Articles

Long non-coding RNA LINC00930 targeting miR-6792-3p/ZBTB16 regulates the proliferation and EMT of pancreatic cancer

Emerging evidence suggests the dysregulation of long non-coding RNAs (lncRNAs) involved in pancreatic cancer (PC). However, the function of LINC00930 in PC has not been elaborated. In this study, we found that LINC00930 was significantly down-regulated in PC cell lines and tissues, and associated with tumor size, lymphatic metastasis, TNM stage and poor prognosis. According to the bioinformatics database, the downregulation of LINC00930 was a common event in PC associated with prognosis and EMT. Overexpression of LINC00930 inhibited the aggressive cancer phenotypes including proliferation, metastasis and epithelial-mesenchymal transition (EMT) of PC in vitro and in vivo. Bioinformatics and dual-luciferase reporter assay indicated that miR-6792-3p could directly bind to LINC00930. Additionally, the Zinc finger and BTB domain containing 16 (ZBTB16) was significantly declined in PC, which was predicted to be the downstream gene of miR-6792-3p. MiR-6792-3p mimic rescued the decreased proliferation, metastasis and EMT caused by ZBTB16 in PC cells. The LINC00930/miR-6792-3p/ZBTB16 axis was associated with the malignant progression and process of PC. The relative expression of LINC00930 was negatively correlated with the expression of miR-6792-3p and was closely linked with ZBTB16 levels in PC. LINC00930 might serve as a potential prognostic biomarker and therapeutic target for PC.

ZNF263 cooperates with ZNF31 to promote the drug resistance and EMT of pancreatic cancer through transactivating RNF126.

The poor prognosis of pancreatic ductal adenocarcinoma (PDAC) is attribute to the aggressive local invasion, distant metastasis and drug resistance of PDAC patients, which was strongly accelerated by epithelial-mesenchymal transition (EMT). In current study, we systematically investigate the role of ZNF263/RNF126 axis in the initiation of EMT in PDAC in vitro and vivo. ZNF263 is firstly identified as a novel transactivation factor of RNF126. Both ZNF263 and RNF126 were overexpressed in PDAC tissues, which were associated with multiple advanced clinical stages and poor prognosis of PDAC patients. ZNF263 overexpression promoted cell proliferation, drug resistance and EMT in vitro via activating RNF126 following by the upregulation of Cyclin D1, N-cad, and MMP9, and the downregulation of E-cad, p21, and p27. ZNF263 silencing contributed to the opposite phenotype. Mechanistically, ZNF263 transactivated RNF126 via binding to its promoter. Further investigations revealed that ZNF263 interacted with ZNF31 to coregulate the transcription of RNF126, which in turn promoted ubiquitination-mediated degradation of PTEN. The downregulation of PTEN activated AKT/Cyclin D1 and AKT/GSK-3β/β-catenin signaling, thereby promoting the malignant phenotype of PDAC. Finally, the coordination of ZNF263 and RNF126 promotes subcutaneous tumor size and distant liver metastasis in vivo. ZNF263, as an oncogene, promotes proliferation, drug resistance and EMT of PDAC through transactivating RNF126.

Lymph node metastasis related gene BICC1 promotes tumor progression by promoting EMT and immune infiltration in pancreatic cancer

BackgroundPancreatic cancer (PC) is one of the most aggressive abdominal malignancies with a poor prognosis and it is urgent to find effective biomarkers for prediction. Although BICC1 expression is related to the survival, no evidence for its role in PC development has been found.MethodsWe used RNA-seq data to screen for molecular markers highly associated with lymph node metastasis. The Cancer Genome Atlas (TCGA) and International Cancer Genome Consortium (ICGC) public databases were used to analyze the expression and prognosis of Differential Expressed Genes (DEGs) in PC. R studio was used for visualization and functional analysis.ResultsBicC Family RNA Binding Protein 1 (BICC1) was a lymph node metastasis-related DEGs in PC patients. Our study found that BICC1 mRNA levels in the tumor tissue were significantly higher and associated with poorer prognosis. Enrichment analysis found that BICC1 was enriched primarily in the Epithelial Mesenchymal Transition (EMT) pathway. Using the ESTIMATE and CIBERSORT algorithms, we found that BICC1 was related to immune cell infiltration. As a regulator of multiple immune checkpoints, BICC1 was also involved in PC’s immune response.ConclusionsBICC1 has the potential to be a new marker in association with lymph node metastasis as well as immune infiltration of PC. In addition to being a prognostic indicator, it may also be a potential therapeutic target.

MBD3 as a Potential Biomarker for Colon Cancer: Implications for Epithelial-Mesenchymal Transition (EMT) Pathways.

The tumor EMT is a crucial event in tumor pathogenesis and progression. Previous research has established MBD3's significant role in pancreatic cancer EMT. However, MBD3's precise role in colon cancer remains unclear and warrants further investigation. Pan-cancer analysis revealed MBD3's differential expression in various tumors and its significant association with tumor occurrence, growth, and progression. Moreover, analysis of single-cell sequencing and clinical data for colon cancer revealed MBD3 expression's negative correlation with clinical indicators such as survival prognosis. Functional enrichment analysis confirmed the association between MBD3 and EMT in colon cancer. Pathological examinations, western blotting, and qRT-PCR in vitro and in vivo validated MBD3's differential expression in colon cancer. Transwell, CCK-8, clone formation, and in vivo tumorigenesis experiments confirmed MBD3's impact on migration, invasion, and proliferation. Our findings demonstrate MBD3 as a potential prognostic marker and therapeutic target for colon cancer.

Hsa_circRNA_001859 regulates pancreatic cancer progression and epithelial-mesenchymal transition through the miR-21-5p/SLC38A2 pathway.

This study attempts to investigate whether hsa_circRNA_001859 (circ_001859) could regulate the proliferation and invasion of pancreatic cancer through the miR-21-5p/SLC38A2 pathway. GSE79634 microarray was analyzed with R package. The expression of circ_001859 in pancreatic cancer tissues and cells was verified by qRT-PCR. After the overexpression of circ_001859, cell proliferation, cell migration and invasion were verified by colony formation and transwell assay. The targeting relationship between miR-21-5p and circ_001859 was predicted by TargetScan and was verified by dual luciferase reporter assay, RNA pull down and qRT-PCR. The effect of miR-21-5p on cell proliferation, migration and invasion were investigated by colony formation and transwell assay respectively. Similarly, the targeting relationship between miR-21-5p and SLC38A2 was predicted by TargetScan and was verified by dual luciferase reporter assay, western blot and qRT-PCR. The effect of SLC38A2 on cell proliferation was investigated by colony formation. Circ_001859 was lowly expressed in pancreatic cancer tissues and cells. In vitro assays showed that overexpression of circ_001859 could inhibit the proliferation, migration and invasion of pancreatic cancer. In addition, this effect was also confirmed in xenograft transplantation model. Circ_001859 could be bind to miR-21-5p and sponge its expression in pancreatic cancer cells. Overexpression of miR-21-5p enhanced the proliferation, migration and invasion ability of pancreatic cancer cells, while the inhibition of miR-21-5p expression suppressed these abilities. Moreover, miR-21-5p directly targeted at SLC38A2 and inhibited SLC38A2 expression levels while circ_001859 up-regulated SLC38A2 levels. SLC38A2 expression knockdown enhanced cell proliferation but SLC38A2 overexpression resulted in decreased proliferation, and effects of SLC38A2 could be rescued by miR-21-5p and circ_001859. In addition, both QRT-PCR and immunofluorescence confirmed that circ_001859 could regulate tumor epithelial-mesenchymal transition (EMT) through the miR-21-5p/SLC38A2 pathway. This study suggests that circ_001859 may inhibit the proliferation, invasion and EMT of pancreatic cancer through the miR-21-5p/SLC38A2 pathway.

Downregulation of circ-STK39 suppresses pancreatic cancer progression by sponging mir-140-3p and regulating TRAM2-mediated epithelial-mesenchymal transition.

Pancreatic cancer (PC) is amongst the most lethal gastrointestinal tumors, which is the seventh leading reason of cancer-related mortality worldwide. Previous studies have indicated that circular RNAs (circRNAs), which is a new type of endogenous noncoding RNA (ncRNA), can mediate tumor progression in diverse tumor types including PC. Whereas precise roles regarding circRNAs and their underlying regulatory mechanisms in PC remain unknown. In the current study, we employed next generation sequencing (NGS) to characterize abnormally expressed circRNAs among PC tissues. Next, we assessed expression levels of one identified circRNA, circ-STK39, in PC cell lines and tissues. Then, using bioinformatics analysis, luciferase reporter, Transwell migration, EdU and CCK-8 assays, we examined the regulatory mechanisms and targets of circ-STK39. Finally, our group explored the circ-STK39 role in PC tumor growth and metastasis in vivo. Our team discovered that circ-STK39 expression increased in PC tissues and cells, suggesting that circ-STK39 may have a role in PC progression. Downregulation of circ-STK39 inhibited PC proliferation and migration. Bioinformatics and luciferase reporter outcomes demonstrated that TRAM2 and miR-140-3p were circ-STK39 downstream targets. TRAM2 overexpression reversed the miR-140-3p overexpression effects upon migration, proliferation and the epithelial-mesenchymal transition (EMT). In this regard, we showed that circ-STK39 downregulation led to decreased migration, proliferation and the EMT of PC via the miR-140-3p/TRAM2 axis.

EGR1 induces EMT in pancreatic cancer via a P300/SNAI2 pathway

BackgroundThe prognosis of pancreatic cancer patients remains relatively poor. Although some patients would receive surgical resection, distant metastasis frequently occurs within one year. Epithelial-mesenchymal transition (EMT), as a pathological mechanism in cancer progression, contributed to the local and distant metastasis of pancreatic cancer.MethodsTissue microarray analysis and immunohistochemistry assays were used to compare the expression of EGR1 in pancreatic cancer and normal pancreatic tissues. Transwell chambers were used to evaluated the migration and invasion ability of cancer cells. Immunofluorescence was utilized to assess the expression of E-cadherin. ChIP-qPCR assay was applied to verify the combination of EGR1 and SNAI2 promoter sequences. Dual-luciferase reporter assay was used to detect the gene promoter activation. Co-IP assay was conducted to verify the interaction of EGR1 and p300/CBP.ResultsEGR1 was highly expressed in pancreatic cancer rather than normal pancreatic tissues and correlated with poor prognosis and cancer metastasis. EGR1 was proved to enhance the migration and invasion ability of pancreatic cells. Besides, EGR1 was positively correlated with EMT process in pancreatic cancer, via a SNAI2-dependent pathway. P300/CBP was found to play an auxiliary role in the transcriptional activation of the SNAI2 gene by EGR1. Finally, in vivo experiments also proved that EGR1 promoted liver metastasis of pancreatic cancer.ConclusionOur findings implied the EMT-promoting effect of EGR1 in pancreatic cancer and revealed the intrinsic mechanism. Blocking the expression of EGR1 may be a new anticancer strategy for pancreatic cancer.Graphical

Histone Modifications Represent a Key Epigenetic Feature of Epithelial-to-Mesenchyme Transition in Pancreatic Cancer

Pancreatic cancer is one of the most lethal malignant diseases due to its high invasiveness, early metastatic properties, rapid disease progression, and typically late diagnosis. Notably, the capacity for pancreatic cancer cells to undergo epithelial-mesenchymal transition (EMT) is key to their tumorigenic and metastatic potential, and is a feature that can explain the therapeutic resistance of such cancers to treatment. Epigenetic modifications are a central molecular feature of EMT, for which histone modifications are most prevalent. The modification of histones is a dynamic process typically carried out by pairs of reverse catalytic enzymes, and the functions of these enzymes are increasingly relevant to our improved understanding of cancer. In this review, we discuss the mechanisms through which histone-modifying enzymes regulate EMT in pancreatic cancer.

S100 family proteins are linked to organoid morphology and EMT in pancreatic cancer

Epithelial-mesenchymal transition (EMT) is a continuum that includes epithelial, partial EMT, and mesenchymal states, each of which is associated with cancer progression, invasive capabilities, and ultimately, metastasis. We used a lineage-traced sporadic model of pancreatic cancer to generate a murine organoid biobank from primary and secondary tumors, including sublines that underwent partial EMT and complete EMT. Using an unbiased proteomics approach, we found that organoid morphology predicts the EMT state, and the solid organoids are associated with a partial EMT signature. We also observed that exogenous TGFβ1 induces solid organoid morphology that is associated with changes in the S100 family, complete EMT, and the formation of high-grade tumors. S100A4 may be a useful biomarker for predicting EMT state, disease progression, and outcome in patients with pancreatic cancer.

NamiRNA-enhancer network of miR-492 activates the NR2C1-TGF-β/Smad3 pathway to promote epithelial-mesenchymal transition of pancreatic cancer.

Pancreatic cancer (PaCa) is one of the most fatal malignancies of the digestive system, and most patients are diagnosed at advanced stages due to the lack of specific and effective tumor-related biomarkers for the early detection of PaCa. miR-492 has been found to be upregulated in PaCa tumor tissue and may serve as a potential therapeutic target. However, the molecular mechanisms by which miR-492 promotes PaCa tumor growth and progression are unclear. In this study, we first found that miR-492 in enhancer loci activated neighboring genes (NR2C1/NDUFA12/TMCC3) and promoted PaCa cell proliferation, migration, and invasion in vitro. We also observed that miR-492-activating genes significantly enriched the TGF-β/Smad3 signaling pathway in PaCa to promote epithelial-mesenchymal transition (EMT) during tumorigenesis and development. Using CRISPR-Cas9 and ChIP assays, we further observed that miR-492 acted as an enhancer trigger, and that antagomiR-492 repressed PaCa tumorigenesis in vivo, decreased the expression levels of serum TGF-β, and suppressed the EMT process by downregulating the expression of NR2C1. Our results demonstrate that miR-492, as an enhancer trigger, facilitates PaCa progression via the NR2C1-TGF-β/Smad3 pathway.

Intracellular C3 Modulates EMT via the Akt/Smad Pathway in Pancreatic Cancer Cells.

We aimed to explore the role of intracellular C3 in pancreatic ductal adenocarcinoma (PDAC). We evaluated C3 expression in PDAC using a gene expression database and tissue microarray. To clarify the role of C3 expression in PDAC, we conducted knockdown experiments using C3 short hairpin RNA (shRNA) in BxPC-3 cells. Differences in protein expression and cell behaviours were analysed. C3 was highly expressed in PDAC and correlated with cancer metastasis. In vitro experiments using BxPX-3 cells showed that C3 and its active form, C3a, were expressed in tumour cells. C3 knockdown reduced cell migration and invasion by inhibiting Akt/Smad pathway activation. TNF-α, not IL-6, enhanced C3 expression in this PDAC cell line. Intracellular C3 may regulate epithelial-mesenchymal transition in pancreatic cancer.

Long Noncoding RNA and Circular RNA: Two Rising Stars in Regulating Epithelial-Mesenchymal Transition of Pancreatic Cancer.

Pancreatic ductal adenocarcinoma (PDAC) is a highly malignant tumor with especially poor prognosis. However, the molecular mechanisms of pancreatic oncogenesis and malignant progression are not fully elucidated. Epithelial-mesenchymal transition (EMT) process is important to drive pancreatic carcinogenesis. Recently, long noncoding RNAs (lncRNAs) and circular RNAs(circRNAs) have been characterized to participate in EMT in PDAC, which can affect the migration and invasion of tumor cells by playing important roles in epigenetic processes, transcription, and post-transcriptional regulation. LncRNAs can act as competing endogenous RNAs (ceRNA) to sequester target microRNAs(miRNAs), bind to the genes which localize physically nearby, and directly interact with EMT-related proteins. Currently known circRNAs mostly regulate the EMT process in PDAC also by acting as a miRNA sponge, directly affecting the protein degradation process. Therefore, exploring the functions of lncRNAs and circRNAs in EMT during pancreatic cancer might help pancreatic cancer treatments.

Urokinase plasminogen activator induces epithelial-mesenchymal and metastasis of pancreatic cancer through plasmin/MMP14/TGF-β axis, which is inhibited by 4-acetyl-antroquinonol B treatment

BackgroundThe current standard therapy for metastatic pancreatic cancer is ineffective, necessitating a new treatment approach for prognosis improvement. The urokinase-plasmin activator (uPA) is a critical factor in epithelial-mesenchymal transition (EMT) and cancer metastasis, but its underlying mechanisms in pancreatic cancer remains elusive. MethodsWe investigated uPA expression in our pancreatic cancer cohort. A bioinformatics approach was used to further determine the role of uPA in pancreatic cancer. We employed MiaPaCa-2 and PANC-1 cell lines to investigate how uPA regulates EMT and metastasis in pancreatic cancer and present a novel approach aimed at inhibiting uPA in pancreatic cancer. ResultsWe observed that higher uPA mRNA expression was significantly associated with overall-poor survival and progression-free survival in pancreatic cancer. uPA was highly expressed in tumor tissue. Gene set enrichment analysis revealed a positive association between uPA mRNA expression and EMT and transforming growth factor β (TGF-β) signaling pathways. Moreover, shRNA-mediated uPA gene knockdown reduced plasmin, MMP14, and TGF-β activation, leading to the inhibition of PANC-1 cells’ EMT marker expression, migration, invasion, and cell viability. Notably, 4-acetyl-antroquinonol B (4-AAQB) treatment suppressed MiaPaCa-2 and PANC-1 cell migratory and invasive abilities by inhibiting the uPA/MMP14/TGF-β axis through upregulation of miR-181d-5p. In the xenograft mouse model of orthotropic pancreatic cancer, 4-AAQB treatment has reduced tumor growth and metastasis rate by deactivating uPA and improving the survival of the mice model. ConclusionAccordingly, to extent of our knowledge and previous studies, we demonstrated that 4-AAQB is an anti Pan-Cancer drug, and may inhibit pancreatic cancer EMT and metastasis and serve as a new therapeutic approach for patients with late-stage pancreatic cancer.

MiR-1301-3p Inhibits Epithelial-Mesenchymal Transition via Targeting RhoA in Pancreatic Cancer.

Micro(mi)RNAs play an essential role in the epithelial-mesenchymal transition (EMT) process in human cancers. This study aimed to uncover the regulatory mechanism of miR-1301-3p on EMT in pancreatic cancer (PC). The miRNA profilings from Gene Expression Omnibus data sets (GSE31568, GSE41372, and GSE32688) demonstrated the downregulation of miR-1301-3p in PC tissues, which was validated with 72 paired PC tissue samples through qRT-PCR detection. The low level of miR-1301-3p was associated with a poor prognosis for PC patients from the PC cohort of The Cancer Genome Atlas and the validation cohort. Gene Ontology analyses indicated that the target genes of miR-1301-3p were involved in cell cycle and adherent junction regulation. In vitro assays revealed that miR-1301-3p suppressed the proliferation and migration abilities of PC cells. Western blotting and luciferase reporter assays suggested that miR-1301-3p inhibited RhoA expression by targeting its 3′-untranslated region; RhoA upregulated N-cadherin and vimentin levels; however, it downregulated the E-cadherin level. In conclusion, our study showed that miR-1301-3p could serve as a prognostic biomarker for PC and suppress PC cell malignancy by targeting the RhoA-induced EMT process.

LINC01128 facilitates the progression of pancreatic cancer through up-regulation of LDHA by targeting miR-561-5p

BackgroundLong non-coding RNAs (lncRNAs) regulate tumor development and metastasis in several types of cancers through various molecular mechanisms. However, the biological role of most lncRNAs in pancreatic cancer (PC) remains unclear. Here, we explored the expression, biological functions, and molecular mechanism of LINC01128 in PC.MethodsQuantitive reverse transcription PCR was used to detect the expression level of LINC01128 in PC tissues and different PC cell lines. A loss-of-function and gain-of-function experiment was used to explore the biological effects of LINC01128 on PC carcinogenesis in vitro and in vivo. Western blot analysis, subcellular fractionation experiment, luciferase reporter gene assay, and MS2-RNA immunoprecipitation experiment were used to study the potential molecular mechanism of LINC01128 during carcinogenesis.ResultsThe expression of LINC01128 was upregulated in PC tissues and cell lines, and overexpression of LINC01128 was significantly related to the poor prognosis of patients with PC. Furthermore, silencing LINC01128 significantly inhibited the proliferation, migration, invasion, and epithelial-mesenchymal transition (EMT) of PC cells in vitro and tumor growth in vivo, while LINC01128 overexpression promoted these processes. Further research showed that LINC01128 acted as a sponge for microRNA miR-561-5p, and lactate dehydrogenase A (LDHA) was the downstream target gene of miR-561-5p. It was also revealed that the expression of miR-561-5p in PC was decreased, and a negative correlation between miR-561-5p and LINC01128 was revealed. Based on rescue experiments, LDHA overexpression partially restored the inhibitory effect of LINC01128 knockdown on proliferation, migration, and invasion of PC cells.ConclusionsLINC01128 promotes the proliferation, migration, invasion, and EMT of PC by regulating the miR-561-5p/LDHA axis, suggesting LINC01128 may be a new prognostic marker and therapeutic target in PC.

The inhibitory effect of LINC00261 upregulation on the pancreatic cancer EMT process is mediated by KLF13 via the mTOR signaling pathway.

The long noncoding RNA LINC00261 was reported to be involved in carcinogenesis and has been validated as a tumor suppressor in pancreatic cancer (PC); however, how LINC00261 is regulated has not been fully examined. Here, we attempted to investigate the upstream and downstream targets of LINC00261 in PC. LINC00261 expression in PC tissues was examined by the Gene Expression Omnibus (GEO) datasets and the Gene Expression Profiling Interactive Analysis (GEPIA) database. The quantitative reverse transcription polymerase chain reaction (qRT-PCR) assays were performed to detect the expression level of LINC00261 in PC cells. The location of LINC00261 in PC cells was identified by RNA fluorescence in situ hybridization (RNA-FISH). Cell Counting Kit-8 (CCK-8), cell apoptosis assay, transwell invasion and migration assays testified the critical role of LINC00261 in PC. The luciferase reporter assay was applied to confirm the binding of LINC00261 to its upstream transcription factor KLF13. The changes in LINC00261 related target protein levels were analyzed by Western blotting assay. LINC00261 was significantly lower in PC tissues and was mainly concentrated in the nucleus. Overexpression of LINC00261 inhibited the invasion and migration of PC cells. Mechanistically, transcription factor KLF13 was confirmed to inhibit the epithelial-mesenchymal transition (EMT) process of PC cells by promoting the transcription of LINC00261 and suppressing the expression of metastasis-associated proteins, such as matrix metalloproteinase MMP2 and vimentin, thus inhibiting the metastasis of PC. LINC00261 regulates PC cell metastasis through the "KLF13-LINC00261-mTOR-P70S6K1-S6" signaling pathway, which provides a significant set of potential PC therapeutic targets.

Long Non-Coding RNAs in Epithelial-Mesenchymal Transition of Pancreatic Cancer.

Non-coding RNAs (ncRNAs), or RNA molecules that do not code for proteins, are generally categorized as either small or long ncRNA (lncRNA) and are involved in the pathogenesis of several diseases including many cancers. Identification of a large number of ncRNAs could help to elucidate previously unknown mechanisms in phenotype regulation. Some ncRNAs are encapsulated by extracellular vesicles (EVs) and transferred to recipient cells to regulate cellular processes, including epigenetic and post-transcriptional regulations. Recent studies have uncovered novel molecular mechanisms and functions of lncRNAs in pancreatic ductal adenocarcinoma (PDAC), one of the most intractable cancers that is highly invasive and metastatic. As the epithelial-mesenchymal transition (EMT) triggers tumor cell invasion and migration, clarification of the roles of lncRNA in EMT and tumor cell stemness would be critical for improving diagnostic and therapeutic approaches in metastatic cancers. This review provides an overview of relevant studies on lncRNA and its involvement with EMT in PDAC. Emerging knowledge offers evidence for the dysregulated expression of lncRNAs and essential insights into the potential contribution of both lncRNAs and EVs in the pathogenesis of PDAC. Future directions and new clinical applications for PDAC are also discussed.

Circ_0092367 Inhibits EMT and Gemcitabine Resistance in Pancreatic Cancer via Regulating the miR-1206/ESRP1 Axis.

Gemcitabine is the first-line treatment for patients with pancreatic cancer (PC), yet most patients develop resistance to gemcitabine. Recent studies showed that circular RNAs (circRNAs) have important regulatory roles in PC progression and chemoresistance. In this study, the ability of circRNA circ_0092367 to enhance gemcitabine efficacy was tested and the underlying molecular mechanism of circ_0092367 was investigated. The expression levels of circ_0092367, miR-1206, and ESRP1 were measured using qRT-PCR experiments. The effects of circ_0092367, miR-1206, and ESRP1 on PC cell lines exposed to gemcitabine were examined by CCK-8 assays. We performed luciferase assays to determine the relationship between circ_0092367 and miR-1206 and between miR-1206 and ESRP1. We demonstrated that circ_0092367 was significantly downregulated in PC tissues and cell lines, and a high expression of circ_0092367 was associated with improved survival in patients with PC. Gain- and loss-of-function assays revealed that circ_0092367 inhibited epithelial–mesenchymal transition (EMT) phenotypes and sensitized PC cells to gemcitabine treatment in vitro and in vivo. Cytoplasmic circ_0092367 could directly repress the levels of miR-1206 and thus upregulate the expression of ESRP1, thereby inhibiting EMT and enhancing the sensitivity of PC cells to gemcitabine treatment. Our findings show that circ_0092367 plays a crucial role in sensitizing PC cells to gemcitabine by modulating the miR-1206/ESRP1 axis, highlighting its potential as a valuable therapeutic target in PC patients.

Yap1-2 Isoform Is the Primary Mediator in TGF-β1 Induced EMT in Pancreatic Cancer.

Pancreatic ductal adenocarcinoma (PDAC) is the most aggressive human malignancy and intrinsically resistant to conventional therapies. YAP1, as a key downstream effector of the Hippo pathway, plays an important role in tumorigenesis including PDAC. Alternative mRNA splicing of YAP1 results in at least 8 protein isoforms, which are divided into two subgroups (YAP1-1 and YAP1-2) based on the presence of either a single or double WW domains. We investigated the functions and regulatory mechanisms of YAP1-1 and YAP1-2 in PDAC cells induced by TGF-β to undergo epithelial-to-mesenchymal transition (EMT). CRISPR-Cas9 and shRNA were used to silence YAP1 expression in pancreatic cancer cells. Re-constituted lentivirus mediated overexpression of each single YAP1 isoform was generated in the parental knockout L3.6 cells. EMT was induced by treatment with TGF-β, EGF and bFGF in parental and the constructed stable cell lines. Western blot and qPCR were used to detect the expression of EMT markers. Scratch wound healing and transwell assays were used to detect cell migration. The stability and subcellular localization of YAP1 proteins were determined by Western blot analysis, immunofluorescence, as well as ubiquitination assays. We showed that TGF-β, EGF and bFGF all significantly promoted EMT in PDAC cells, which was inhibited by knockdown of YAP1 expression. Interestingly, YAP1-1 stable cells exhibited a stronger migratory ability than YAP1-2 cells under normal culture condition. However, upon TGF-β treatment, L3.6-YAP1-2 cells exhibited a stronger migratory ability than L3.6-YAP1-1 cells. Mechanistically, TGF-β treatment preferentially stabilizes YAP1-2 and enhances its nuclear localization. Furthermore, TGF-β-induced EMT and YAP1-2 activity were both blocked by inhibition of AKT signaling. Our results showed that both YAP1-1 and YAP1-2 isoforms are important mediators in the EMT process of pancreatic cancer. However, YAP1-2 is more important in mediating TGF-β-induced EMT, which requires AKT signaling.

Silencing of circRNA circ_0001666 Represses EMT in Pancreatic Cancer Through Upregulating miR-1251 and Downregulating SOX4.

BackgroundPancreatic cancer (PC) is an aggressive malignancy and has a poor prognosis. Although emerging research has revealed that circular RNAs (circRNAs) are crucial modulators that control tumor development and metastasis, their functional involvement in PC has not been well characterized. Here, we examined whether and how circRNA circ_0001666 governs epithelial-mesenchymal transition (EMT) in PC.MethodsWe investigated the effects of circ_0001666 on EMT and PC cell invasion by gain- and loss-of-function assays. We also explored the mechanisms underlying the functions of circ_0001666 in PC cells.ResultsWe found that circ_0001666 is highly expressed in PC tissues and PC cell lines. Patients with high circ_0001666 expression had shorter survival times. In vitro and in vivo experiments have demonstrated that upregulation of circ_0001666 facilitates PC cell proliferation, EMT and invasiveness, whereas knockdown of circ_0001666 exhibits opposite functions. Moreover, circ_0001666 is able to bind to miR-1251, thus increasing the expression of SOX4, which is a direct downstream effector of miR-1251. The oncogenic effects of circ_0001666 on EMT and PC cell invasion were rescued by miR-1251 overexpression.ConclusionsThese results suggested that circ_0001666 acts as an oncogenic circRNA to promote EMT and invasion of PC cells through sponging miR-1251, and indicated that circ_0001666 could be explored as a potential therapeutic target for PC.