Epithelial-mesenchymal transition (EMT) and activated extracellular signal-regulated kinase (p-Erk) in surgically resected pancreatic cancer

The SMYD3-MAP3K2 signaling axis promotes tumor aggressiveness and metastasis in prostate cancer

Aberrant activation of Ras/Raf/mitogen-activated protein kinase (MAPK) signaling is frequently linked to metastatic prostate cancer (PCa); therefore, the characterization of modulators of this pathway is critical for defining therapeutic vulnerabilities for metastatic PCa. The lysine methyltransferase SET and MYND domain 3 (SMYD3) methylates MAPK kinase kinase 2 (MAP3K2) in some cancers, causing enhanced activation of MAPK signaling. In PCa, SMYD3 is frequently overexpressed and associated with disease severity; however, its molecular function in promoting tumorigenesis has not been defined. We demonstrate that SMYD3 critically regulates tumor-associated phenotypes via its methyltransferase activity in PCa cells and mouse xenograft models. SMYD3-dependent methylation of MAP3K2 promotes epithelial-mesenchymal transition associated behaviors by altering the abundance of the intermediate filament vimentin. Furthermore, activation of the SMYD3-MAP3K2 signaling axis supports a positive feedback loop continually promoting high levels of SMYD3. Our data provide insight into signaling pathways involved in metastatic PCa and enhance understanding of mechanistic functions for SMYD3 to reveal potential therapeutic opportunities for PCa.

Chimeric antibody targeting unique epitope on onco-mucin16 reduces tumor burden in pancreatic and lung malignancies

Aberrantly expressed onco-mucin 16 (MUC16) and its post-cleavage generated surface tethered carboxy-terminal (MUC16-Cter) domain are strongly associated with poor prognosis and lethality of pancreatic (PC) and non-small cell lung cancer (NSCLC). To date, most anti-MUC16 antibodies are directed towards the extracellular domain of MUC16 (CA125), which is usually cleaved and shed in the circulation hence obscuring antibody accessibility to the cancer cells. Herein, we establish the utility of targeting a post-cleavage generated, surface-tethered oncogenic MUC16 carboxy-terminal (MUC16-Cter) domain by using a novel chimeric antibody in human IgG1 format, ch5E6, whose epitope expression directly correlates with disease severity in both cancers. ch5E6 binds and interferes with MUC16-associated oncogenesis, suppresses the downstream signaling pFAK(Y397)/p-p70S6K(T389)/N-cadherin axis and exert antiproliferative effects in cancer cells, 3D organoids, and tumor xenografts of both PC and NSCLC. The robust clinical correlations observed between MUC16 and N-cadherin in patient tumors and metastatic samples imply ch5E6 potential in targeting a complex and significantly occurring phenomenon of epithelial to mesenchymal transition (EMT) associated with disease aggressiveness. Our study supports evaluating ch5E6 with standard-of-care drugs, to potentially augment treatment outcomes in malignancies inflicted with MUC16-associated poor prognosis.

DNA Polymerase Theta Plays a Critical Role in Pancreatic Cancer Development and Metastasis

Pancreatic ductal adenocarcinoma (PDAC), due to its genomic heterogeneity and lack of effective treatment, despite decades of intensive research, will become the second leading cause of cancer-related deaths by 2030. Step-wise acquisition of mutations, due to genomic instability, is considered to drive the development of PDAC; the KRAS mutation occurs in 95 to 100% of human PDAC, and is already detectable in early premalignant lesions designated as pancreatic intraepithelial neoplasia (PanIN). This mutation is possibly the key event leading to genomic instability and PDAC development. Our study aimed to investigate the role of the error-prone DNA double-strand breaks (DSBs) repair pathway, alt-EJ, in the presence of the KRAS G12D mutation in pancreatic cancer development. Our findings show that oncogenic KRAS contributes to increasing the expression of Polθ, Lig3, and Mre11, key components of alt-EJ in both mouse and human PDAC models. We further confirm increased catalytic activity of alt-EJ in a mouse and human model of PDAC bearing the KRAS G12D mutation. Subsequently, we focused on estimating the impact of alt-EJ inactivation by polymerase theta (Polθ) deletion on pancreatic cancer development, and survival in genetically engineered mouse models (GEMMs) and cancer patients. Here, we show that even though Polθ deficiency does not fully prevent the development of pancreatic cancer, it significantly delays the onset of PanIN formation, prolongs the overall survival of experimental mice, and correlates with the overall survival of pancreatic cancer patients in the TCGA database. Our study clearly demonstrates the role of alt-EJ in the development of PDAC, and alt-EJ may be an attractive therapeutic target for pancreatic cancer patients.

Pathology and physiology of acid‑sensitive ion channels in the digestive system (Review)

As a major proton-gated cation channel, acid-sensitive ion channels (ASICs) can perceive large extracellular pH changes. ASICs play an important role in the occurrence and development of diseases of various organs and tissues including in the heart, brain, and gastrointestinal tract, as well as in tumor proliferation, invasion, and metastasis in acidosis and regulation of an acidic microenvironment. The permeability of ASICs to sodium and calcium ions is the basis of their physiological and pathological roles in the body. This review summarizes the physiological and pathological mechanisms of ASICs in digestive system diseases, which plays an important role in the early diagnosis, treatment, and prognosis of digestive system diseases related to ASIC expression.

Tumor‐targeted fluorescence labeling systems for cancer diagnosis and treatment

Conventional imaging techniques are available for clinical identification of tumor sites. However, detecting metastatic tumor cells that are spreading from primary tumor sites using conventional imaging techniques remains difficult. In contrast, fluorescence‐based labeling systems are useful tools for detecting tumor cells at the single‐cell level in cancer research. The ability to detect fluorescent‐labeled tumor cells enables investigations of the biodistribution of tumor cells for the diagnosis and treatment of cancer. For example, the presence of fluorescent tumor cells in the peripheral blood of cancer patients is a predictive biomarker for early diagnosis of distant metastasis. The elimination of fluorescent tumor cells without damaging normal tissues is ideal for minimally invasive treatment of cancer. To capture fluorescent tumor cells within normal tissues, however, tumor‐specific activated target molecules are needed. This review focuses on recent advances in tumor‐targeted fluorescence labeling systems, in which indirect reporter labeling using tumor‐specific promoters is applied to fluorescence labeling of tumor cells for the diagnosis and treatment of cancer. Telomerase promoter‐dependent fluorescence labeling using replication‐competent viral vectors produces fluorescent proteins that can be used to detect and eliminate telomerase‐positive tumor cells. Tissue‐specific promoter‐dependent fluorescence labeling enables identification of specific tumor cells. Vimentin promoter‐dependent fluorescence labeling is a useful tool for identifying tumor cells that undergo epithelial–mesenchymal transition (EMT). The evaluation of tumor cells undergoing EMT is important for accurately assessing metastatic potential. Thus, tumor‐targeted fluorescence labeling systems represent novel platforms that enable the capture of tumor cells for the diagnosis and treatment of cancer.

High expression of both desmoplastic stroma and epithelial to mesenchymal transition markers associate with shorter survival in pancreatic ductal adenocarcinoma

Desmoplastic stroma (DS) and the epithelial-to-mesenchymal transition (EMT) play a key role in pancreatic ductal adenocarcinoma (PDAC) progression. To date, however, the combined expression of DS and EMT markers, and their association with variations in survival within each clinical stage and degree of tumor differentiation is unknown. The purpose of this study was to investigate the association between expression of DS and EMT markers and survival variability in patients diagnosed with PDAC. We examined the expression levels of DS markers alpha smooth muscle actin (α-SMA), fibronectin, and vimentin, and the EMT markers epithelial cell adhesion molecule (EPCAM), pan-cytokeratin, and vimentin, by immunohistochemistry using a tissue microarray in a retrospective cohort of 25 patients with PDAC. The results were examined for association with survival by clinical stage and by degree of tumor differentiation. High expression of DS markers -α-SMA, fibronectin, and vimentin- was associated with decreased survival at intermediate and advanced clinical stages (p=0.006-0.03), as well as with both poorly and moderately differentiated tumor grades (p=0.01-0.02). Interestingly, the same pattern was observed for EMT markers, i.e., EPCAM, pan-cytokeratin, and vimentin (p=0.00008-0.03). High expression of DS and EMT markers within each clinical stage and degree of tumor differentiation was associated with lower PDAC survival. Evaluation of these markers may have a prognostic impact on survival time variation in patients with PDAC.

microRNA-21 Regulates Stemness in Pancreatic Ductal Adenocarcinoma Cells

Pancreatic ductal adenocarcinoma (PDAC) is the most common and aggressive type of pancreatic cancer (PCa) with a low survival rate. microRNAs (miRs) are endogenous, non-coding RNAs that moderate numerous biological processes. miRs have been associated with the chemoresistance and metastasis of PDAC and the presence of a subpopulation of highly plastic "stem"-like cells within the tumor, known as cancer stem cells (CSCs). In this study, we investigated the role of miR-21, which is highly expressed in Panc-1 and MiaPaCa-2 PDAC cells in association with CSCs. Following miR-21 knockouts (KO) from both MiaPaCa-2 and Panc-1 cell lines, reversed expressions of epithelial-mesenchymal transition (EMT) and CSCs markers were observed. The expression patterns of key CSC markers, including CD44, CD133, CX-C chemokine receptor type 4 (CXCR4), and aldehyde dehydrogenase-1 (ALDH1), were changed depending on miR-21 status. miR-21 (KO) suppressed cellular invasion of Panc-1 and MiaPaCa-2 cells, as well as the cellular proliferation of MiaPaCa-2 cells. Our data suggest that miR-21 is involved in the stemness of PDAC cells, may play roles in mesenchymal transition, and that miR-21 poses as a novel, functional biomarker for PDAC aggressiveness.

Tumor Microenvironment in Pancreatic Intraepithelial Neoplasia

Simple Summary

Pancreatic ductal adenocarcinoma (PDAC) is a very aggressive neoplasm with a poor survival rate. This is mainly due to late detection, which substantially limits therapy options. A better understanding of the early phases of pancreatic carcinogenesis is fundamental for improving patient prognosis in the future. In this article, we focused on the tumor microenvironment (TME), which provides the biological niche for the development of PDAC from its most common precursor lesions, PanIN (pancreatic intraepithelial neoplasias).

Abstract

Pancreatic ductal adenocarcinoma (PDAC) is one of the most aggressive tumors with a poor prognosis. A characteristic of PDAC is the formation of an immunosuppressive tumor microenvironment (TME) that facilitates bypassing of the immune surveillance. The TME consists of a desmoplastic stroma, largely composed of cancer-associated fibroblasts (CAFs), immunosuppressive immune cells, immunoregulatory soluble factors, neural network cells, and endothelial cells with complex interactions. PDAC develops from various precursor lesions such as pancreatic intraepithelial neoplasia (PanIN), intraductal papillary mucinous neoplasms (IPMN), mucinous cystic neoplasms (MCN), and possibly, atypical flat lesions (AFL). In this review, we focus on the composition of the TME in PanINs to reveal detailed insights into the complex restructuring of the TME at early time points in PDAC progression and to explore ways of modifying the TME to slow or even halt tumor progression.

Cell Lineage Infidelity in PDAC Progression and Therapy Resistance

Infidelity to cell fate occurs when differentiated cells lose their original identity and either revert to a more multipotent state or transdifferentiate into a different cell type, either within the same embryonic lineage or in an entirely different one. Whilst in certain circumstances, such as in wound repair, this process is beneficial, it can be hijacked by cancer cells to drive disease initiation and progression. Cell phenotype switching has been shown to also serve as a mechanism of drug resistance in some epithelial cancers. In pancreatic ductal adenocarcinoma (PDAC), the role of lineage infidelity and phenotype switching is still unclear. Two consensus molecular subtypes of PDAC have been proposed that mainly reflect the existence of cell lineages with different degrees of fidelity to pancreatic endodermal precursors. Indeed, the classical subtype of PDAC is characterised by the expression of endodermal lineage specifying transcription factors, while the more aggressive basal-like/squamous subtype is defined by epigenetic downregulation of endodermal genes and alterations in chromatin modifiers. Here, we summarise the current knowledge of mechanisms (genetic and epigenetic) of cell fate switching in PDAC and discuss how pancreatic organoids might help increase our understanding of both cell-intrinsic and cell-extrinsic factors governing lineage infidelity during the distinct phases of PDAC evolution.

Morphological Heterogeneity in Pancreatic Cancer Reflects Structural and Functional Divergence

Simple Summary

Pancreatic cancer has a poor prognosis, which is largely due to resistance to treatment. Tumor heterogeneity is a known cause for treatment failure and has been studied at the molecular level. Morphological heterogeneity is common but has not been investigated, despite the fact that pathology examination is an integral part of clinical diagnostics. This study assessed whether morphological heterogeneity reflects structural and functional diversity in key cancer biological processes. Using archival tissues from resected pancreatic cancer, we selected four common and distinct morphological phenotypes and demonstrated that these differed significantly for a panel of 26 structural and functional features of the cancer-cell and stromal compartments. The strong link between these features and morphological phenotypes allowed prediction of the latter based on the results for the panel of features. The findings of this study indicate that morphological heterogeneity reflects biological diversity and that its assessment may potentially provide clinically relevant information.

Abstract

Inter- and intratumor heterogeneity is an important cause of treatment failure. In human pancreatic cancer (PC), heterogeneity has been investigated almost exclusively at the genomic and transcriptional level. Morphological heterogeneity, though prominent and potentially easily assessable in clinical practice, remains unexplored. This proof-of-concept study aims at demonstrating that morphological heterogeneity reflects structural and functional divergence. From the wide morphological spectrum of conventional PC, four common and distinctive patterns were investigated in 233 foci from 39 surgical specimens. Twenty-six features involved in key biological processes in PC were analyzed (immuno-)histochemically and morphometrically: cancer cell proliferation (Ki67) and migration (collagen fiber alignment, MMP14), cancer stem cells (CD44, CD133, ALDH1), amount, composition and spatial arrangement of extracellular matrix (epithelial proximity, total collagen, collagen I and III, fibronectin, hyaluronan), cancer-associated fibroblasts (density, αSMA), and cancer-stroma interactions (integrins α2, α5, α1; caveolin-1). All features differed significantly between at least two of the patterns. Stromal and cancer-cell-related features co-varied with morphology and allowed prediction of the morphological pattern. In conclusion, morphological heterogeneity in the cancer-cell and stromal compartments of PC correlates with structural and functional diversity. As such, histopathology has the potential to inform on the operationality of key biological processes in individual tumors.

Tepotinib Inhibits the Epithelial-Mesenchymal Transition and Tumor Growth of Gastric Cancers by Increasing GSK3β, E-Cadherin, and Mucin 5AC and 6 Levels

Aberrant expression of mucins (MUCs) can promote the epithelial–mesenchymal transition (EMT), which leads to enhanced tumorigenesis. Carcinogenesis-related pathways involving c-MET and β-catenin are associated with MUCs. In this study, we characterized the expression of EMT-relevant proteins including MET, β-catenin, and E-cadherin in human gastric cancer (GC) cell lines, and further characterized the differential susceptibility of these cell lines compared with the c-MET inhibitor tepotinib. We assessed the antitumor activity of tepotinib in GC cell lines. The effects of tepotinib on cell viability, apoptotic cell death, EMT, and c-MET and β-catenin signaling were evaluated by 3-(4,5 dimethylthiazol-2-yl)-5-(3-carboxymethoxyphenyl-2-(4-sulfophenyl)-2H-tetrazolium (MTS), flow cytometry, Western blotting, and qRT-PCR. The antitumor efficacy was assessed in MKN45 xenograft mice. Tepotinib treatment induced apoptosis in c-MET-amplified SNU620, MKN45, and KATO III cells, but had no effect on c-MET-reduced MKN28 or AGS cells. Tepotinib treatment also significantly reduced the protein levels of phosphorylated and total c-MET, phosphorylated and total ERK, β-catenin, and c-MYC in SNU620 and MKN45 cells. In contrast, this drug was only slightly active against KATO III cells. Notably, tepotinib significantly reduced the expression of EMT-promoting genes such as MMP7, COX-2, WNT1, MUC5B, and c-MYC in c-MET-amplified GC cells and increased the expression of EMT-suppressing genes such as MUC5AC, MUC6, GSK3β, and E-cadherin. In a mouse model, tepotinib exhibited good antitumor growth activity along with increased E-cadherin and decreased phosphorylated c-MET (phospho-c-MET) protein levels. Collectively, these results suggest that tepotinib suppresses tumor growth and migration by negatively regulating c-MET-induced EMT. These findings provide new insights into the mechanism by which MUC5AC and MUC6 contribute to GC progression.

From Genetic Alterations to Tumor Microenvironment: The Ariadne's String in Pancreatic Cancer

The threatening notoriety of pancreatic cancer mainly arises from its negligible early diagnosis, highly aggressive progression, failure of conventional therapeutic options and consequent very poor prognosis. The most important driver genes of pancreatic cancer are the oncogene KRAS and the tumor suppressors TP53, CDKN2A, and SMAD4. Although the presence of few drivers, several signaling pathways are involved in the oncogenesis of this cancer type, some of them with promising targets for precision oncology. Pancreatic cancer is recognized as one of immunosuppressive phenotype cancer: it is characterized by a fibrotic-desmoplastic stroma, in which there is an intensive cross-talk between several cellular (e.g., fibroblasts, myeloid cells, lymphocytes, endothelial, and myeloid cells) and acellular (collagen, fibronectin, and soluble factors) components. In this review; we aim to describe the current knowledge of the genetic/biological landscape of pancreatic cancer and the composition of its tumor microenvironment; in order to better direct in the intrinsic labyrinth of this complex tumor type. Indeed; disentangling the genetic and molecular characteristics of cancer cells and the environment in which they evolve may represent the crucial step towards more effective therapeutic strategies

Musashi2 promotes EGF-induced EMT in pancreatic cancer via ZEB1-ERK/MAPK signaling

Background

Our previous study showed Musashi2 (MSI2) promoted chemotherapy resistance and pernicious biology of pancreatic cancer (PC) by down-regulating Numb and p53. We further explored the novel molecular mechanism involving its oncogenic role in PC development.

Methods

We investigated the potential role and mechanism of MSI2 in EGF-induced EMT in PC in vitro and vivo.

Results

EGF enhanced EGFR (epidermal growth factor receptor) phosphorylation, induced EMT and activated ZEB1-ERK/MAPK signaling in 2 PC cells. However, MSI2 silencing reversed EGF stimulated function, including inhibiting EGF-promoted EMT-like cell morphology and EGF-enhanced cell invasion and migration. Meanwhile, MSI2 silencing inhibited EGF-enhanced EGFR phosphorylation at tyrosine 1068 and reversed EGF-induced change of the key proteins in EMT and ZEB1-ERK/MAPK signaling (ZEB1, E-cad, ZO-1, β-catenin, pERK and c-Myc). Additionally, MSI2 was co-stained and co-immunoprecipitated with ZEB1, pERK and c-Myc in PC cells by IF and co-IP, implying a close interaction between them. In vivo, MSI2 silencing inhibited pancreatic tumor size in situ and distant liver metastases. A close relationship of MSI2 with EMT and ZEB1-ERK/MAPK signaling were also observed in vivo and human PC samples, which coordinately promoted the poor prognosis of PC patients.

Conclusions

MSI2 promotes EGF-induced EMT in PC via ZEB1-ERK/MAPK signaling.

Three-microRNA expression signature predicts survival in triple-negative breast cancer

Triple-negative breast cancer (TNBC) is a specific type of breast cancer with poor overall survival (OS) time. Previous studies revealed that microRNAs (miRNAs/miRs) serve important roles in the pathogenesis, progression and prognosis of TNBC. The present study analyzed the miRNA expression and clinical data of patients with TNBC downloaded from The Cancer Genome Atlas. A total of 194 differentially expressed miRNAs were identified between TNBC and matched normal tissues using the cut-off criteria of P<0.05 and |log2 fold change|>2. Of these miRNAs, 65 were downregulated and 129 were upregulated. Using Kaplan-Meier survival analysis, a total of 77 miRNAs that were closely associated with OS time were identified (P<0.05). The intersection of the 77 miRNAs and 194 differentially expressed miRNAs revealed six miRNAs. Log-rank tests based on survival curves were performed and two miRNAs were eliminated. The prognostic value of the remaining four miRNAs was evaluated with a Cox proportional hazards model using multiple logistic regression with forward stepwise selection of variables. Three miRNAs (miR-21-3p, miR-659-5p and miR-200b-5p) were subsequently identified as independent risk factors associated with OS time in the model. Gene Ontology and Kyoto Encyclopedia of Genes and Genomes pathway enrichment analyses revealed that the target genes of these three miRNAs were mainly involved in ‘cell protein metabolism’, ‘RNA transcriptional regulation’, ‘cell migration’, ‘MAPK signaling pathway’, ‘ErbB signaling pathway’, ‘prolactin signaling pathway’ and ‘adherens junctions’. Taken together, the results obtained in the present study suggested that the three-miRNA signature may serve as a prognostic biomarker for patients with TNBC.

Visualization of epithelial-mesenchymal transition in an inflammatory microenvironment-colorectal cancer network

Epithelial-mesenchymal transition (EMT) is a biological process by which epithelial cells acquire mesenchymal characteristics. In malignant tumors, EMT is crucial for acquisition of a mesenchymal phenotype with invasive and metastatic properties, leading to tumor progression. An inflammatory microenvironment is thought to be responsible for the development and progression of colorectal cancer (CRC); however, the precise role of inflammatory microenvironments in EMT-related CRC progression remains unclear. Here, we show the spatiotemporal visualization of CRC cells undergoing EMT using a fluorescence-guided EMT imaging system in which the mesenchymal vimentin promoter drives red fluorescent protein (RFP) expression. An inflammatory microenvironment including TNF-α, IL-1β, and cytokine-secreting inflammatory macrophages induced RFP expression in association with the EMT phenotype in CRC cells. In vivo experiments further demonstrated the distribution of RFP-positive CRC cells in rectal and metastatic tumors. Our data suggest that the EMT imaging system described here is a powerful tool for monitoring EMT in inflammatory microenvironment-CRC networks.

Targeting Epithelial Mesenchymal Plasticity in Pancreatic Cancer: A Compendium of Preclinical Discovery in a Heterogeneous Disease

Pancreatic Ductal Adenocarcinoma (PDAC) is a particularly insidious and aggressive disease that causes significant mortality worldwide. The direct correlation between PDAC incidence, disease progression, and mortality highlights the critical need to understand the mechanisms by which PDAC cells rapidly progress to drive metastatic disease in order to identify actionable vulnerabilities. One such proposed vulnerability is epithelial mesenchymal plasticity (EMP), a process whereby neoplastic epithelial cells delaminate from their neighbours, either collectively or individually, allowing for their subsequent invasion into host tissue. This disruption of tissue homeostasis, particularly in PDAC, further promotes cellular transformation by inducing inflammatory interactions with the stromal compartment, which in turn contributes to intratumoural heterogeneity. This review describes the role of EMP in PDAC, and the preclinical target discovery that has been conducted to identify the molecular regulators and effectors of this EMP program. While inhibition of individual targets may provide therapeutic insights, a single ‘master-key’ remains elusive, making their collective interactions of greater importance in controlling the behaviours’ of heterogeneous tumour cell populations. Much work has been undertaken to understand key transcriptional programs that drive EMP in certain contexts, however, a collaborative appreciation for the subtle, context-dependent programs governing EMP regulation is needed in order to design therapeutic strategies to curb PDAC mortality.

TGF-β signaling promotes tube-structure-forming growth in pancreatic duct adenocarcinoma

Tube-forming growth is an essential histological feature of pancreatic duct adenocarcinoma (PDAC) and of the pancreatic duct epithelium; nevertheless, the nature of the signals that start to form the tubular structures remains unknown. Here, we showed the clonal growth of PDAC cell lines in a three-dimensional (3D) culture experiment that modeled the clonal growth of PDAC. At the beginning of this study, we isolated the sphere- and tube-forming clones from established mouse pancreatic cancer cell lines via limiting dilution culture using collagen gel. Compared with cells in spherical structures, the cells in the formed tubes exhibited a lower CK19 expression in 3D culture and in the tumor that grew in the abdominal cavity of nude mice. Conversely, the expression of the transforming growth factor β (TGF-β)-signaling target mRNAs was higher in the formed tube vs the spherical structures, suggesting that TGF-β signaling is more active in the tube-forming process than the sphere-forming process. Treatment of sphere-forming clones with TGF-β1 induced tube-forming growth, upregulated the TGF-β-signaling target mRNAs, and yielded electron microscopic findings of a fading epithelial phenotype. In contrast, the elimination of TGF-β-signaling activation by treatment with inhibitors diminished the tube-forming growth and suppressed the expression of the TGF-β-signaling target mRNAs. Moreover, upregulation of the Fn1, Mmp2, and Snai1 mRNAs, which are hallmarks of tube-forming growth in PDAC, was demonstrated in a mouse model of carcinogenesis showing rapid progression because of the aggressive invasion of tube-forming cancer. Our study suggests that the tube-forming growth of PDAC relies on the activation of TGF-β signaling and highlights the importance of the formation of tube structures.

Gemcitabine-induced epithelial-mesenchymal transition-like changes sustain chemoresistance of pancreatic cancer cells of mesenchymal-like phenotype

Growing body of evidence suggests that epithelial-mesenchymal transition (EMT) is a critical process in tumor progression and chemoresistance in pancreatic cancer (PC). The aim of this study was to analyze the role of EMT-like changes in acquisition of resistance to gemcitabine in pancreatic cells of the mesenchymal or epithelial phenotype. Therefore, chemoresistant BxPC-3, Capan-2, Panc-1, and MiaPaca-2 cells were selected by chronic exposure to increasing concentrations of gemcitabine. We show that gemcitabine-resistant Panc-1 and MiaPaca-2 cells of mesenchymal-like phenotype undergo further EMT-like molecular changes mediated by ERK-ZEB-1 pathway, and that inhibition of ERK1/2 phosphorylation or ZEB-1 expression resulted in a decrease in chemoresistance. Conversely, gemcitabine-resistant BxPC-3 and Capan-2 cells of epithelial-like phenotype did not show such typical EMT-like molecular changes although the expression of the tight junction marker occludin could be found decreased. In pancreatic cancer patients, high ZEB-1 expression was associated with tumor invasion and tumor budding. In addition, tumor budding was essentially observed in patients treated with neoadjuvant chemotherapy. These findings support the notion that gemcitabine treatment induces EMT-like changes that sustain invasion and chemoresistance in PC cells.

Rigidity controls human desmoplastic matrix anisotropy to enable pancreatic cancer cell spread via extracellular signal-regulated kinase 2

It is predicted that pancreatic ductal adenocarcinoma (PDAC) will become the second most lethal cancer in the US by 2030. PDAC includes a fibrous-like stroma, desmoplasia, encompassing most of the tumor mass, which is produced by cancer-associated fibroblasts (CAFs) and includes their cell-derived extracellular matrices (CDMs). Since elimination of desmoplasia has proven detrimental to patients, CDM reprogramming, as opposed to stromal ablation, is therapeutically desirable. Hence, efforts are being made to harness desmoplasia's anti-tumor functions. We conducted biomechanical manipulations, using variations of pathological and physiological substrates in vitro, to culture patient-harvested CAFs and generate CDMs that restrict PDAC growth and spread. We posited that extrinsic modulation of the environment, via substrate rigidity, influences CAF's cell-intrinsic forces affecting CDM production. Substrates used were polyacrylamide gels of physiological (~1.5 kPa) or pathological (~7 kPa) stiffnesses. Results showed that physiological substrates influenced CAFs to generate CDMs similar to normal/control fibroblasts. We found CDMs to be softer than the corresponding underlying substrates, and CDM fiber anisotropy (i.e., alignment) to be biphasic and informed via substrate-imparted morphological CAF aspect ratios. The biphasic nature of CDM fiber anisotropy was mathematically modeled and proposed a correlation between CAF aspect ratios and CDM alignment; regulated by extrinsic and intrinsic forces to conserve minimal free energy. Biomechanical manipulation of CDMs, generated on physiologically soft substrates, leads to reduction in nuclear translocation of pERK1/2 in KRAS mutated pancreatic cells. ERK2 was found essential for CDM-regulated tumor cell spread. In vitro findings correlated with in vivo observations; nuclear pERK1/2 is significantly high in human PDAC samples. The study suggests that altering underlying substrates enable CAFs to remodel CDMs and restrict pancreatic cancer cell spread in an ERK2 dependent manner.

Quasimesenchymal phenotype predicts systemic metastasis in pancreatic ductal adenocarcinoma

Metastasis following surgical resection is a leading cause of mortality in pancreatic ductal adenocarcinoma. Epithelial-mesenchymal transition is thought to play an important role in metastasis, although its clinical relevance in metastasis remains uncertain. We evaluated a panel of RNA in-situ hybridization probes for epithelial-mesenchymal transition-related genes expressed in circulating tumor cells. We assessed the predictive value of this panel for metastasis in pancreatic ductal adenocarcinoma and, to determine if the phenotype is generalizable between cancers, in colonic adenocarcinoma. One hundred fifty-eight pancreatic ductal adenocarcinomas and 205 colonic adenocarcinomas were classified as epithelial or quasimesenchymal phenotype using dual colorimetric RNA-in-situ hybridization. SMAD4 expression on pancreatic ductal adenocarcinomas was assessed by immunohistochemistry. Pancreatic ductal adenocarcinomas with quasimesenchymal phenotype had a significantly shorter disease-specific survival (P = 0.031) and metastasis-free survival (P = 0.0001) than those with an epithelial phenotype. Pancreatic ductal adenocarcinomas with SMAD4 loss also had lower disease-specific survival (P = 0.041) and metastasis-free survival (P = 0.001) than those with intact SMAD4. However, the quasimesenchymal phenotype proved a more robust predictor of metastases-area under the curve for quasimesenchymal = 0.8; SMAD4 = 0.6. The quasimesenchymal phenotype also predicted metastasis-free survival (P = 0.004) in colonic adenocarcinoma. Epithelial-mesenchymal transition defined two phenotypes with distinct metastatic capabilities-epithelial phenotype tumors with predominantly organ-confined disease and quasimesenchymal phenotype with high risk of metastatic disease in two epithelial malignancies. Collectively, this work validates the relevance of epithelial-mesenchymal transition in human gastrointestinal tumors.

Inhibition of ERK1/2 in cancer-associated pancreatic stellate cells suppresses cancer-stromal interaction and metastasis

Background

Extracellular signal-regulated kinases (ERKs) have been related to multiple cancers, including breast cancer, hepatocellular cancer, lung cancer and colorectal cancer. ERK1/2 inhibitor can suppress growth of KRAS-mutant pancreatic tumors by targeting cancer cell. However, no studies have shown the expression of ERK1/2 on pancreatic stromal and its effect on pancreatic cancer–stromal interaction.

Methods

Immunohistochemistry and western blotting were performed to detect the expression of p-ERK1/2 in pancreatic tissues and cells. Cell viability assay was used to study IC50 of ERK inhibitor on pancreatic cancer cells (PCCs) and primary cancer-associated pancreatic stellate cells (PSCs). Transwell migration, invasion, cell viability assay, senescence β-galactosidase staining were performed to determine the effect of ERK inhibitor on PCCs and PSCs in vitro and in vivo. The expression of key factors involved in autophagy and epithelial-to-mesenchymal transition (EMT) process were evaluated by western blotting. The expression of key factors related to cell invasiveness and malignancy were confirmed by qRT-PCR. Co-transplantation of PCC Organoid and PSC using a splenic xenograft mouse model was used to evaluated combined treatment of ERK inhibitor and autophagy inhibitor.

Results

Immunohistochemical staining in pancreatic tumor samples and transgenetic mice detected p-ERK1/2 expression in both cancer cells and stromal cells. In pancreatic tissues, p-ERK1/2 was strongly expressed in cancer-associated PSCs compared with cancer cells and normal PSCs. PSCs were also significantly more sensitive to ERK1/2 inhibitor treatment. Inhibition of ERK1/2 suppressed EMT transition in HMPCCs, upregulated cellular senescence markers, activated autophagy in cancer-associated PSCs; and suppressed cancer–stromal interaction, which enhanced invasiveness and viability of cancer cells. We also found that chloroquine, an autophagy inhibitor, suppressed ERK inhibition-induced autophagy and promoted PSC cellular senescence, leading to significantly decreased cell proliferation. The combination of an ERK inhibitor and autophagy inhibitor suppressed liver metastasis in a splenic pancreatic cancer organoid xenograft mouse model.

Conclusions

These data indicate that inhibition of ERK1/2 in cancer-associated pancreatic stellate cells suppresses cancer–stromal interaction and metastasis.

Electronic supplementary material

The online version of this article (10.1186/s13046-019-1226-8) contains supplementary material, which is available to authorized users.

Loss of Disabled-2 Expression in Pancreatic Cancer Progression

Pancreatic ductal adenocarcinoma (PDAC) is a highly aggressive cancer type characterized by rapid metastasis and resistance to chemotherapy, properties that are shared by cancer stem cells (CSCs). In pancreatic cancer, tumor cells which possess the properties of CSCs also phenotypically resemble cells that have undergone epithelial-to-mesenchymal transition or EMT. Disabled-2 (Dab2) is a multifunctional scaffold protein frequently downregulated in cancer that has been linked to the process of EMT. However, the role of Dab2 in pancreatic cancer development and progression remains unclear. Downregulation of Dab2 expression in pancreatic cancer cell lines was found to trigger induction of genes characteristic of EMT and the CSC phenotype, while overexpression of Dab2 in the Panc1 cell line blocked the process of TGFβ-stimulated EMT. In addition, selective inhibition of the TGFβRI/RII receptors was found to reverse genes altered by Dab2 downregulation. Dab2 mRNA expression was found to be decreased in PDAC tumor samples, as compared to levels observed in normal pancreatic tissue. Methylation of the Dab2 gene promoter was demonstrated in Stage I PDAC tumors and in the MiaPaCa2 cell line, suggesting that promoter methylation may silence Dab2 expression early in pancreatic cancer progression. These results suggest that Dab2 may function as a tumor suppressor in pancreatic cancer by modulation of the TGFβ-stimulated EMT and CSC phenotype.

Crumbs3 is a critical factor that regulates invasion and metastasis of colon adenocarcinoma via the specific interaction with FGFR1

Epithelial cell polarity regulator Crumbs3 (Crb3), a mammalian homolog within the Drosophila Crb gene family, was initially identified as an essential embryonic development factor. It is recently implicated in tumor suppression, though its specific functions are controversial. We here demonstrate that Crb3 strongly promotes tumor invasion and metastasis of human colon adenocarcinoma cells. Crb3 centrality to tumor migration was supported by strong expression at invasive front and metastatic foci of colonic adenocarcinoma of the patient tissues. Accordingly, two different Crb3‐knockout (KO) lines, Crb3‐KO (Crb3 −/−) DLD‐1 and Crb3‐KO WiDr from human colonic adenocarcinomas, were generated by the CRISPR‐Cas9 system. Crb3‐KO DLD‐1 cells exhibited loss of cellular mobility in vitro and dramatic suppression of liver metastases in vivo in contrast to the wild type of DLD‐1. Unlike DLD‐1, Crb3‐KO WiDr mobility and metastasis were unaffected, which were similar to wild‐type WiDr. Proteome analysis of Crb3‐coimmunopreciptated proteins identified different respective fibroblast growth factor receptor (FGFR) isotypes specifically bound to Crb3 isoform a through their intracellular domain. In DLD‐1, Crb3 showed membranous localization of FGFR1 leading to its functional activation, whereas Crb3 bound to cytoplasmic FGFR4 in WiDr without FGFR1 expression, leading to cellular growth. Correlative expression between Crb3 and FGFR1 was consistently detected in primary and metastatic colorectal cancer patient tissues. Taking these together, Crb3 critically accelerates cell migration, namely invasion and metastasis of human colon cancers, through specific interaction to FGFR1 on colon cancer cells.

What's new?

Epithelial cell polarity regulator Crumbs3 (Crb3) was initially identified as an essential embryonic development factor. More recently, it has been implicated in tumor suppression, though its specific functions remain controversial. Here, the authors demonstrate that Crb3 strongly promotes tumor invasion and metastasis of human colon adenocarcinoma cells. They identify among the binding partners of Crb3 the FGF receptors family, which is pivotal to tumor cell dynamics including proliferation, migration, and differentiation. Crb3 colocalizes with FGFR1 to activate downstream signaling and critically accelerate tumor migration and metastasis of human colon cancers.

Long noncoding RNA XIST regulates the EGF receptor to promote TGF-β1-induced epithelial-mesenchymal transition in pancreatic cancer

BACKGROUND

This study focuses on the lncRNA XIST (X inactive-specific transcript), an lncRNA involved in multiple human cancers, and investigates the functional significance of XIST and the molecular mechanisms underlying the epithelial-mesenchymal transition (EMT) in pancreatic cancer (PC).

METHODS

Clinical specimens from 25 patients as well as 5 human PC cell lines were analyzed for XIST, YAP, and microRNA(miR)-34a by quantitative real-time PCR (qRT-PCR) and immunohistochemistry. To investigate how XIST influences cell proliferation, invasiveness, and apoptosis in PC, we performed the CCK-8 assays, Transwell assays, and flow cytometry. Luciferase reporter assays, qRT-PCR, and Western blot were applied to prove that miR-34a directly binds to XIST.

RESULTS

Up-regulation of XIST and Yes associated protein (YAP) and down-regulation of miR-34a were consistently observed in the clinical specimens and PC cell lines. Silencing XIST reduced the expression of YAP and suppressed transforming growth factor (TGF)-β1-induced EMT, while over-expression of XIST increased the expression of YAP and promoted EMT. In addition, inhibition of epidermal growth factor receptor (EGFR) hampered the XIST-promoted EMT. The results from the luciferase reporter assays confirmed that miR-34a directly targets XIST and suggested that XIST regulates cell proliferation, invasiveness, and apoptosis in PC by sponging miR-34a.

CONCLUSIONS

XIST promotes TGF-β1-induced EMT by regulating the miR-34a-YAP-EGFR axis in PC.

Clinical and Prognostic Significance of the Epithelial-Mesenchymal Transition in Stage IA Lung Adenocarcinoma: A Propensity Score-Matched Analysis

BACKGROUND

The epithelial-mesenchymal transition (EMT) describes the process through which cells lose epithelial characteristics and gain a mesenchymal phenotype. The EMT contributes to tumor invasion and cancer progression, and is associated with metastasis and poor survival of patients with non-small-cell lung cancer. However, little is known about the relationships between the EMT and the clinicopathologic characteristics of patients with stage IA lung adenocarcinoma.

PATIENTS AND METHODS

We conducted immunohistochemical analysis of the expression of the EMT markers E-cadherin and vimentin of specimens acquired from 183 consecutive patients with stage IA lung adenocarcinoma. The clinicopathologic significance of the association of the EMT status with E-cadherin and vimentin expression was analyzed after propensity score matching.

RESULTS

E-cadherin and vimentin were detected in 68.3% and 18.6% of stage IA lung adenocarcinomas, respectively. The presence of cells with EMT conversion was associated with older patient age. A propensity score-matched cohort (128 patients) was used for further analyses. Computed tomography revealed that tumors with EMT conversion showed solid-dominant nodules compared to those without conversion. Survival analysis after propensity score matching showed that the EMT correlated with poor disease-free survival (hazard ratio = 2.57, P = .0451) and overall survival (hazard ratio = 4.23, P = .0471). Multivariate analysis revealed that the EMT was an independent predictor of shorter disease-free survival.

CONCLUSION

The EMT was a significant predictor of poor prognosis of patients with stage IA lung adenocarcinoma. The EMT status may serve as an indicator for administering adjuvant therapy.

Stromal fibronectin expression in patients with resected pancreatic ductal adenocarcinoma

BACKGROUND

Pancreatic ductal adenocarcinoma (PDAC) is characterized by an extremely dense stroma, which has a fundamental role in tumor progression. Fibronectin (FN1) is the main constituent of the tumor stroma in pancreatic cancer. This study aimed to explore the association between FN1 and clinicopathological characteristics and disease survival.

METHODS

Formalin-fixed paraffin-embedded tissue samples from 138 patients with PDAC were constructed into a tissue microarray, followed by immunohistochemical analysis with a recombinant monoclonal FN1 antibody. Chi-square test or Fisher's exact test were used for comparison of FN1 expression and relevant clinicopathological parameters. Kaplan-Meier survival curves and Cox regression analyses were used to assess the association between FN1 and survival.

RESULTS

FN1 was detected in the stromal compartment in most cases (117/138, 84.8%). Compared to the low FN1 expression group, the high FN1 expression group had significantly larger tumor size (P = 0.002), more advanced T stage (P = 0.039) and N stage (P = 0.009), and also worse AJCC stage (P = 0.003). However, stromal FN1 expression was not associated with disease-free survival or overall survival.

CONCLUSIONS

This study suggests that high stromal FN1 expression is associated with aggressive tumor characteristics in patients with resected PDAC. However, no association between FN1 expression and survival was found.

Src kinase inhibition restores E-cadherin expression in dasatinib-sensitive pancreatic cancer cells

The Src family of non-receptor tyrosine kinases are frequently activated in pancreatic ductal adenocarcinoma (PDAC), contributing to disease progression through downregulation of E-cadherin and induction of epithelial-to-mesenchymal transition (EMT). The purpose of this study was to examine the efficacy of Src kinase inhibition in restoring E-cadherin levels in PDAC. Immunohistochemical analysis of human PDAC samples showed Src activation is inversely correlated with E-cadherin levels. Protein and mRNA levels of E-cadherin, the gene expression of its various transcriptional repressors (Zeb1, Snail, Slug, LEF-1, TWIST), and changes in sub-cellular localization of E-cadherin/β-catenin in PDAC cells were characterized in response to treatment with the Src inhibitor, dasatinib (DST). DST repressed Slug mRNA expression, promoted E-cadherin transcription, and increased total and membranous E-cadherin/β-catenin levels in drug-sensitive PDAC cells (BxPC3 and SW1990), however no change was observed in drug-resistant PANC1 cells. BxPC3, PANC1, and MiaPaCa-2 flank tumor xenografts were treated with DST to examine changes in E-cadherin levels in vivo. Although DST inhibited Src phosphorylation in all xenograft models, E-cadherin levels were only restored in BxPC3 xenograft tumors. These results suggest that Src kinase inhibition reverses EMT in drug-sensitive PDAC cells through Slug-mediated repression of E-cadherin and identifies E-cadherin as potential biomarker for determining response to DST treatment.

β-Sitosterol and Gemcitabine Exhibit Synergistic Anti-pancreatic Cancer Activity by Modulating Apoptosis and Inhibiting Epithelial-Mesenchymal Transition by Deactivating Akt/GSK-3β Signaling

β-sitosterol (BS), a major bioactive constituent present in plants, has shown potent anti-cancer activity against many human cancer cells, but its activity in pancreatic cancer (PC) cells has rarely been reported. Gemcitabine (GEM) is one of the first-line drugs for PC therapy, however, the treatment effect is not sustained due to prolonged drug resistance. In this study, we firstly studied the anti-PC activity and the mechanism of BS alone and in combination with GEM in vitro and in vivo. BS effectively inhibited the growth of PC cell lines by inhibiting proliferation, inducing G0/G1 phase arrest and apoptosis, suppressed the NF- kB activity, and increased expression of the protein Bax but decreased expression of the protein Bcl-2. Moreover, BS inhibited migration and invasion and downregulated epithelial–mesenchymal transition (EMT) markers and AKT/GSK-3β signaling pathways. Furthermore, the combination of BS and GEM exhibited a significant synergistic effect in MIAPaCa-2 and BXPC-3 cells. More importantly, the combined treatment with BS and GEM lead to significant growth inhibition of PC xenografts. Overall, our data revealed a promising treatment option for PC by the combination therapy of BS and GEM.

Tenascin C, Fibronectin, and Tumor-Stroma Ratio in Pancreatic Ductal Adenocarcinoma

OBJECTIVES

Pancreatic ductal adenocarcinoma (PDAC) is characterized by abundant stroma with increased expression of tenascin C and fibronectin. Their role and tumor-stroma ratio in PDAC are not well known. The aim of this study was to evaluate tenascin C and fibronectin expression and tumor-stroma ratio and their prognostic relevance in PDAC.

METHODS

Ninety-five resected PDACs were immunohistochemically stained for tenascin C and fibronectin, and the expression was separately assessed in tumor bulk and front. Tumor-stroma ratio was determined with sections stained with hematoxylin-eosin.

RESULTS

Tenascin C and fibronectin were abundantly expressed in the stroma of PDAC, but absent in adjacent normal pancreatic tissue. Fibronectin expression of the bulk was associated with high T class (P = 0.045). In the main analysis, tenascin C and fibronectin expression and tumor-stroma ratio were not associated with patient survival. In a subgroup analysis of early-stage PDAC (T1-T2 tumors), high tenascin C expression in the tumor bulk was associated with poor prognosis (hazard ratio, 8.23; 95% confidence interval, 2.71-24.96).

CONCLUSIONS

Tenascin C and fibronectin are abundantly expressed in PDAC, but they seem to have no major association with patient survival. However, in early-stage PDAC, tenascin C expression of the tumor bulk may have prognostic impact. Tumor-stroma ratio has no prognostic value in PDAC.

MicroRNA-494 acts as a tumor suppressor in pancreatic cancer, inhibiting epithelial-mesenchymal transition, migration and invasion by binding to SDC1

Pancreatic cancer (PC) is the fourth most common cause of cancer‑related mortality in the industrialized world. Emerging evidence indicates that a variety of microRNAs (miRNAs or miRs) are involved in the development of PC. The aim of the present study was to elucidate the mechanisms through which miR‑494 affects the epithelial‑mesenchymal transition (EMT) and invasion of PC cells by binding to syndecan 1 (SDC1). PC tissues and pancreatitis tissues were collected, and the regulatory effects of miR‑494 on SDC1 were validated using bioinformatics analysis and a dual‑luciferase report gene assay. The cell line with the highest SDC1 expression was selected for use in the following experiments. The role of miR‑494 in EMT was assessed by measuring the expression of SDC1, E‑cadherin and vimentin. Cell proliferation was assessed using a cell counting kit (CCK)‑8 assay, migration was measured using a scratch test, invasion was assessed with a Transwell assay and apoptosis was detected by flow cytometry. Finally, a xenograft tumor model was constructed in nude mice to observe tumor growth in vivo. We found that SDC1 protein expression was significantly higher in the PC tissues. SDC1 was verified as a target gene of miR‑494. The SW1990 cell line was selected for use in further experiments as it had the lowest miR‑494 expression and the highest SDC1 expression. Our results also demonstrated that miR‑494 overexpression and SDC1 silencing significantly decreased the mRNA and protein expression of SDC1 and vimentin in SW1990 cells, while it increased E‑cadherin expression and apoptosis, and inhibited cell growth, migration, invasion and tumor growth. On the whole, the findings of this study demonstrated that miR‑494 is able to downregulate SDC1 expression, thereby inhibiting the progression of PC. These findings reveal a novel mechanism through which miR‑494 affects the development of PC and may thus provide a basis for the application of miR‑494 in pancreatic oncology.

Melatonin inhibits osteosarcoma stem cells by suppressing SOX9-mediated signaling

AIMS

Melatonin (N-acetyl-5-methoxytryptamine) has been reported to suppress epithelial-mesenchymal transition and cancer stem cells in some types of cancer. However, the effects of melatonin on the osteosarcoma stem cells, epithelial-mesenchymal transition and metastasis of osteosarcoma are still not clear. The present study was conducted to dissect the activity of melatonin on the osteosarcoma stem cells and the underlying mechanisms.

MAIN METHODS

MTT, wound healing, transwell assay and western blotting were conducted to determine the effect of melatonin on osteosarcoma cell invasion and migration and downregulation of SOX9-mediated signaling. Tumor spheroid assay and FACS analysis were performed to analyze the inhibition of the osteosarcoma stem cells. In vivo model for tumor formation and metastasis from single cell clone was used to evaluate the suppression of osteosarcoma stem cells by melatonin.

KEY FINDINGS

We demonstrated that melatonin potently suppresses the migration and invasion of osteosarcoma cells. Furthermore, melatonin significantly inhibits the sarcosphere formation of osteosarcoma stem cells and regulates EMT markers of osteosarcoma cells. In vivo mice model showed that melatonin significantly inhibits the initiation and metastasis of osteosarcoma. SOX9 is the key transcription factor mediating the effect of melatonin. Melatonin inhibited of cancer stem cell by down-regulation of SOX9-mediated signaling pathway in osteosarcoma.

SIGNIFICANCE

Collectively, these results deepen the understanding of the biological functions of melatonin and provide new insights for the intervention of osteosarcoma stem cells.

Poorly differentiated ductal adenocarcinoma of the pancreas with rapid progression in a young man

Pancreatic cancer in young adults is very rare. We report a case of young-onset poorly differentiated pancreatic ductal adenocarcinoma with rapid progression and poor prognosis in a 31-year-old Japanese man with no obvious family history of malignancy. Preoperative examinations revealed a mass lesion in the body of the pancreas, accompanied by a slightly dilated main pancreatic duct distal to the mass lesion. Pancreatic cancer with acute pancreatitis was suspected because of an elevation of serum pancreatic enzyme and tumor marker, along with imaging findings. Distal pancreatectomy with resection of the common hepatic artery and splenectomy along with lymph node dissection was performed. Microscopically, the tumor was mainly composed of poorly differentiated ductal adenocarcinoma. The postoperative course was uneventful, but the patient had multiple liver metastases 2 months postoperatively, in spite of adjuvant chemotherapy, and died 8 months postoperatively. This case may represent a rare instance of young-onset poorly differentiated ductal adenocarcinoma with rapid progression and may indicate potential risk factors of pancreatic cancer in young adults.

HS-173, a novel PI3K inhibitor suppresses EMT and metastasis in pancreatic cancer

Pancreatic cancer is one of the most aggressive solid malignancies prone to metastasis. Epithelial-mesenchymal transition (EMT) contributes to cancer invasiveness and drug resistance. In this study, we investigated whether HS-173, a novel PI3K inhibitor blocked the process of EMT in pancreatic cancer. HS-173 inhibited the growth of pancreatic cancer cells in a dose- and time-dependent manner. Moreover, it significantly suppressed the TGF-β-induced migration and invasion, as well as reversed TGF-β-induced mesenchymal cell morphology. Also, HS-173 reduced EMT by increasing epithelial markers and decreasing the mesenchymal markers by blocking the PI3K/AKT/mTOR and Smad2/3 signaling pathways in pancreatic cancer cells. In addition, HS-173 clearly suppressed tumor growth without drug toxicity in both xenograft and orthotopic mouse models. Furthermore, to explore the anti-metastatic effect of HS-173, we established pancreatic cancer metastatic mouse models and found that it significantly inhibited metastatic dissemination of the primary tumor to liver and lung. Taken together, our findings demonstrate that HS-173 can efficiently suppress EMT and metastasis by inhibiting PI3K/AKT/mTOR and Smad2/3 signaling pathways, suggesting it can be a potential candidate for the treatment of advanced stage pancreatic cancer.

Targeting tumor-associated macrophages to combat pancreatic cancer

The tumor microenvironment is replete with cells that evolve with and provide support to tumor cells during the transition to malignancy. The hijacking of the immune system in the pancreatic tumor microenvironment is suggested to contribute to the failure to date to produce significant improvements in pancreatic cancer survival by various chemotherapeutics. Regulatory T cells, myeloid derived suppressor cells, and fibroblasts, all of which constitute a complex ecology microenvironment, can suppress CD8+ T cells and NK cells, thus inhibiting effector immune responses. Tumor-associated macrophages (TAM) are versatile immune cells that can express different functional programs in response to stimuli in tumor microenvironment at different stages of pancreatic cancer development. TAM have been implicated in suppression of anti-tumorigenic immune responses, promotion of cancer cell proliferation, stimulation of tumor angiogenesis and extracellular matrix breakdown, and subsequent enhancement of tumor invasion and metastasis. Many emerging agents that have demonstrated efficacy in combating other types of tumors via modulation of macrophages in tumor microenvironments are, however, only marginally studied for pancreatic cancer prevention and treatment. A better understanding of the paradoxical roles of TAM in pancreatic cancer may pave the way to novel preventive and therapeutic approaches. Here we give an overview of the recruitment and differentiation of macrophages, TAM and pancreatic cancer progression and prognosis, as well as the potential preventive and therapeutic targets that interact with TAM for pancreatic cancer prevention and treatment.

Tumor budding is a prognostic factor linked to epithelial mesenchymal transition in pancreatic ductal adenocarcinoma. Study report and literature review

BACKGROUND

Pancreatic ductal adenocarcinoma (PDAC) has a devastatingly poor prognosis. Surgical resection is undertaken in only 20% of patients. Most of well-known prognostic factors reflect tumor stage more than its biology. So it is important to identify new biological indicators related to survival in order to develop new therapies.

OBJECTIVE

To determine the relation between tumor budding and Epithelial Mesenchymal Transition (EMT) and to evaluate their impact on survival for patients after resection of PDAC.

METHODS

We herein report a retrospective study of 50 patients with resected PDAC. Tumor budding, immunohistochemical expression of vimentin and other standard factors were correlated with survival using the Kaplan-Meier method and Cox multivariable survival analysis. For tumor budding assessment, an inter-observer variability study was performed using 100 images of tumor slides stained with Hematoxylin & Eosin and Pan-Cytokeratin.

RESULTS

Tumor budding was present in all tumors. A substantial agreement between six pathologists was established in distinguishing high-grade from low-grade budding (κ = 0.6 and 0.73 for H&E and PCK images respectively). High-grade budding was identified in 56% of tumors (28/50). It was an adverse prognostic factor independent of tumor size, resection margins status, nodal status and vascular invasion (p = 0.008). Tumor budding was significantly associated with vimentin expression (p = 0.002).

CONCLUSIONS

The association of tumor budding with vimentin expression supported the idea that EMT is a key process in PDAC responsible for progression and drug resistance. Consequently, the elucidation of EMT molecular biology and development of new targeted therapy may improve disease outcome.

Prognostic significance of E-cadherin and ZEB1 expression in intraductal papillary mucinous neoplasm

There is an urgent need to investigate the genetic changes that occur in intraductal papillary mucinous neoplasm (IPMN), which is a well-known precursor of pancreatic cancer. In this study, gene expression profiling was performed by removing unwanted variation to determine the differentially expressed genes (DEGs) associated with malignant progression of IPMN. Among the identified DEGs, zinc finger E-box binding homeobox 1 (ZEB1) and E-cadherin, a crucial regulator of epithelial-to-mesenchymal transition (EMT), was validated among identified DEGs.

A total of 76 fresh-frozen tissues were used for gene expression profiling and formalin-fixed, paraffin-embedded blocks from 87 patients were obtained for immunohistochemical analysis. Loss of E-cadherin expression (p = 0.023, odd ratio [OR] = 4.923) and expression of ZEB1 in stromal cells (stromal ZEB1, p < 0.001, OR = 26.800) were significantly correlated with degree of dysplasia. The hazard of death was significantly increased in patients with loss of E-cadherin expression (hazard ratio [HR] = 13.718, p = 0.004), expression of epithelial ZEB1 (HR = 19.117, p = 0.001), and stromal ZEB1 (HR = 6.373, p = 0.043).

Based on the results of this study, loss of E-cadherin and expression of stromal ZEB1 are associated with increased risk of malignant progression. Epithelial and stromal ZEB1, as well as E-cadherin may be strong predictors of survival in patients with IPMN. Our finding suggests that these EMT markers may be utilized as potential prognosticators and may be used to improve and personalize treatment of IPMN.

Vimentin Is Required for Lung Adenocarcinoma Metastasis via Heterotypic Tumor Cell-Cancer-Associated Fibroblast Interactions during Collective Invasion

Purpose: Vimentin is an epithelial-to-mesenchymal transition (EMT) biomarker and intermediate filament protein that functions during cell migration to maintain structure and motility. Despite the abundance of clinical data linking vimentin to poor patient outcome, it is unclear if vimentin is required for metastasis or is a correlative biomarker. We developed a novel genetically engineered mouse model (GEMM) to probe vimentin in lung adenocarcinoma metastasis.Experimental Design: We used the LSL-Kras^G12D/Lkb1^fl/fl/Vim^-/- model (KLV^-/-), which incorporates a whole-body knockout of vimentin and is derived from the Cre-dependent LSL-Kras^G12D/Lkb1^fl/fl model (KLV^+/+). We compared the metastatic phenotypes of the GEMMs and analyzed primary tumors from the KLV models and lung adenocarcinoma patients to assess vimentin expression and function.Results: Characterization of KLV^+/+ and KLV^-/- mice shows that although vimentin is not required for primary lung tumor growth, vimentin is required for metastasis, and vimentin loss generates lower grade primary tumors. Interestingly, in the KLV^+/+ mice, vimentin was not expressed in tumor cells but in cancer-associated fibroblasts (CAFs) surrounding collective invasion packs (CIPs) of epithelial tumor cells, with significantly less CIPs in KLV^-/- mice. CIPs correlate with tumor grade and are vimentin-negative and E-cadherin-positive, indicating a lack of cancer cell EMT. A similar heterotypic staining pattern was observed in human lung adenocarcinoma samples. In vitro studies show that vimentin is required for CAF motility to lead tumor cell invasion, supporting a vimentin-dependent model of collective invasion.Conclusions: These data show that vimentin is required for lung adenocarcinoma metastasis by maintaining heterotypic tumor cell-CAF interactions during collective invasion. Clin Cancer Res; 24(2); 420-32. ©2017 AACR.

Aminopeptidase A initiates tumorigenesis and enhances tumor cell stemness via TWIST1 upregulation in colorectal cancer

Metastasis accounts for the high mortality rate associated with colorectal cancer (CRC), but metastasis regulators are not fully understood. To identify a novel gene involved in tumor metastasis, we used oligonucleotide microarrays, transcriptome distance analyses, and machine learning algorithms to determine links between primary and metastatic colorectal cancers. Aminopeptidase A (APA; also known as ENPEP) was selected as our focus because its relationship with colorectal cancer requires clarification. Higher APA mRNA levels were observed in patients in advanced stages of cancer, suggesting a correlation between ENPEP and degree of malignancy. Our data also indicate that APA overexpression in CRC cells induced cell migration, invasion, anchorage-independent capability, and mesenchyme-like characteristics (e.g., EMT markers). We also observed TWIST induction in APA-overexpressing SW480 cells and TWIST down-regulation in HT29 cells knocked down with APA. Both APA silencing and impaired APA activity were found to reduce migratory capacity, cancer anchorage, stemness properties, and drug resistance in vitro and in vivo. We therefore suggest that APA enzymatic activity affects tumor initiation and cancer malignancy in a TWIST-dependent manner. Results from RT-qPCR and the immunohistochemical staining of specimens taken from CRC patients indicate a significant correlation between APA and TWIST. According to data from SurvExpress analyses of TWIST1 and APA mRNA expression profiles, high APA and TWIST expression are positively correlated with poor CRC prognosis. APA may act as a prognostic factor and/or therapeutic target for CRC metastasis and recurrence.

Expression of the scaffold connector enhancer of kinase suppressor of Ras 1 (CNKSR1) is correlated with clinical outcome in pancreatic cancer

Background

Despite the near universal occurrence of activating codon 12 KRAS somatic variants in pancreatic cancer, there is considerable heterogeneity in the molecular make-up, MAPK/ERK pathway activation states, and clinical outcome in this disease. We analyzed the expression levels of CNKSR1, a scaffold that influences MAPK/ERK pathway activity, in clinical pancreas cancer specimens and their impact on survival of patients with pancreatic cancer.

Methods

Immunohistochemical staining for CNKSR1 expression was performed on 120 specimens from three independent pancreatic cancer tissue registries, phospho-ERK levels were measured in 86 samples. Expression was divided into CNKSR1 low and CNKSR1 high and correlated with clinicopathological variables including overall survival using multivariate Cox proportional hazard ratio models.

Results

CNKSR1 expression was increased in tumors compared to matched normal uninvolved resection specimens (p = 0.004). 28.3% (34/120) of patient specimens stained as CNKSR1 low compared to 71.7% (86/120) of specimens which stained as CNKSR1 high. High CNKSR1 expression was more prevalent in low grade tumors (p = 0.04). In multivariate analysis, low CNKSR1 expression status was independently correlated with decreased overall survival (HR = 2.146; 95% CI 1.34 to 3.43). When stratifying primary, non-metastatic tumor biopsies by CNKSR1 expression, resection was associated with improved survival in patients with high CNKSR1 expression (p < 0.0001) but not low CNKSR1 expression (p = 0.3666). Pancreatic tumors with nuclear in addition to cytoplasmic CNKSR1 staining (32/107) showed increased nuclear phospho-ERK expression compared to tumor with cytoplasmic CNKSR1 staining only (p = 0.017).

Conclusion

CNKSR1 expression is increased in pancreatic tissue specimens and was found to be an independent prognostic marker of overall survival. CNKSR1 may help to identify patient subgroups with unfavorable tumor biology in order to improve risk stratification and treatment selection. Cellular distribution of CNKSR1 was correlated with nuclear pERK expression.

ASIC1 and ASIC3 contribute to acidity-induced EMT of pancreatic cancer through activating Ca2+/RhoA pathway

Extracellular acid can have important effects on cancer cells. Acid-sensing ion channels (ASICs), which emerged as key receptors for extracellular acidic pH, are differently expressed during various diseases and have been implicated in underlying pathogenesis. This study reports that ASIC1 and ASIC3 are mainly expressed on membrane of pancreatic cancer cells and upregulated in pancreatic cancer tissues. ASIC1 and ASIC3 are responsible for an acidity-induced inward current, which is required for elevation of intracellular Ca²⁺ concentration ([Ca²⁺]i). Inhibition of ASIC1 and ASIC3 with siRNA or pharmacological inhibitor significantly decreased [Ca²⁺]i and its downstream RhoA during acidity and, thus, suppressed acidity-induced epithelial–mesenchymal transition (EMT) of pancreatic cancer cells. Meanwhile, downregulating [Ca²⁺]i with calcium chelating agent BAPTA-AM or knockdown of RhoA with siRNA also significantly repressed acidity-induced EMT of pancreatic cancer cells. Significantly, although without obvious effect on proliferation, knockdown of ASIC1 and ASIC3 in pancreatic cancer cells significantly suppresses liver and lung metastasis in xenograft model. In addition, ASIC1 and ASIC3 are positively correlated with expression of mesenchymal marker vimentin, but inversely correlated with epithelial marker E-cadherin in pancreatic cancer cells. In conclusion, this study indicates that ASICs are master regulator of acidity-induced EMT. In addition, the data demonstrate a functional link between ASICs and [Ca²⁺]i/RhoA pathway, which contributes to the acidity-induced EMT.

miR-202 Diminishes TGFβ Receptors and Attenuates TGFβ1-Induced EMT in Pancreatic Cancer

Previous studies in our laboratory identified that 3-deazaneplanocin A (DZNep), a carbocyclic adenosine analog and histone methyl transferase inhibitor, suppresses TGFβ-induced epithelial-to-mesenchymal (EMT) characteristics. In addition, DZNep epigenetically reprograms miRNAs to regulate endogenous TGFβ1 levels via miR-663/4787-mediated RNA interference (Mol Cancer Res. 2016 Sep 13. pii: molcanres.0083.2016) (1). Although DZNep also attenuates exogenous TGFβ-induced EMT response, the mechanism of this inhibition was unclear. Here, DZNep induced miR-202-5p to target both TGFβ receptors, TGFBR1 and TGFBR2, for RNA interference and thereby contributes to the suppression of exogenous TGFβ-induced EMT in pancreatic cancer cells. Lentiviral overexpression of miR-202 significantly reduced the protein levels of both TGFβ receptors and suppressed TGFβ signaling and EMT phenotypic characteristics of cultured parenchymal pancreatic cancer cells. Consistently, transfection of anti-miRNAs against miR-202-5p resulted in increased TGFBR1 and TGFBR2 protein expressions and induced EMT characteristics in these cells. In stellate pancreatic cells, miR-202 overexpression slowed growth as well as reduced stromal extracellular membrane matrix protein expression. In orthotopic pancreatic cancer mouse models, both immunodeficient and immunocompetent, miR-202 reduced tumor burden and metastasis. Together, these findings demonstrate an alternative mechanism of DZNep in suppressing TGFβ signaling at the receptor level and uncover the EMT-suppressing role of miR-202 in pancreatic cancer.Implications: These findings support the possibility of combining small molecule-based (e.g., DZNep analogs) or large molecule-based (e.g., miRNAs) epigenetic modifiers with conventional nucleoside analogs (e.g., gemcitabine, capecitabine) to improve the antimetastatic potential of current pancreatic cancer therapy. Mol Cancer Res; 15(8); 1029-39. ©2017 AACR.

Increased semaphorin 3c expression promotes tumor growth and metastasis in pancreatic ductal adenocarcinoma by activating the ERK1/2 signaling pathway

Pancreatic cancer is characterized by neural alterations and aberrant expression of neural-specific factors. Semaphorins have been recognized as key contributors in axon guidance, the immune response and tumor progression. Recent studies have suggested the involvement of Semaphorin 3c (sema3c) in tumorigenesis and metastasis in numerous types of cancer, however, the clinical significance of sema3c and its role in the growth and metastasis of pancreatic ductal adenocarcinoma (PDAC) remain unclear. In this study, we found that aberrant sema3c expression was positively associated with a particular tumor stage and correlated with poor survival of PDAC patients. Knockdown of sema3c attenuated proliferation, migration, invasion and epithelial-mesenchymal transition (EMT) in a pancreatic cancer cell line and reduced PDAC cell tumorigenesis upon xenotransplantation into NOD/SCID mice. Overexpression of sema3c produced the opposite effects and promoted the extracellular signal-regulated kinase (ERK)1/2 signaling pathway. Overall, our findings demonstrate that aberrant expression of sema3c is correlated with poor prognosis of PDAC patients and promotes tumor growth and metastasis by activating ERK1/2 signaling pathway.

Inhibition of S-Adenosylmethionine-Dependent Methyltransferase Attenuates TGFβ1-Induced EMT and Metastasis in Pancreatic Cancer: Putative Roles of miR-663a and miR-4787-5p

The identification of epigenetic reversal agents for use in combination chemotherapies to treat human pancreatic ductal adenocarcinomas (PDAC) remains an unmet clinical need. Pharmacologic inhibitors of Enhancer of Zeste Homolog 2 (EZH2) are emerging as potential histone methylation reversal agents for the treatment of various solid tumors and leukemia; however, the surprisingly small set of mRNA targets identified with EZH2 knockdown suggests novel mechanisms contribute to their antitumorigenic effects. Here, 3-deazaneplanocin-A (DZNep), an inhibitor of S-adenosyl-L-homocysteine hydrolase and EZH2 histone lysine-N-methyltransferase, significantly reprograms noncoding microRNA (miRNA) expression and dampens TGFβ1-induced epithelial-to-mesenchymal (EMT) signals in pancreatic cancer. In particular, miR-663a and miR-4787-5p were identified as PDAC-downregulated miRNAs that were reactivated by DZNep to directly target TGFβ1 for RNA interference. Lentiviral overexpression of miR-663a and miR-4787-5p reduced TGFβ1 synthesis and secretion in PDAC cells and partially phenocopied DZNep's EMT-resisting effects, whereas locked nucleic acid (LNA) antagomiRNAs counteracted them. DZNep, miR-663a, and miR-4787-5p reduced tumor burden in vivo and metastases in an orthotopic mouse pancreatic tumor model. Taken together, these findings suggest the epigenetic reprogramming of miRNAs by synthetic histone methylation reversal agents as a viable approach to attenuate TGFβ1-induced EMT features in human PDAC and uncover putative miRNA targets involved in the process.

IMPLICATIONS

The findings support the potential for synthetic histone methylation reversal agents to be included in future epigenetic-chemotherapeutic combination therapies for pancreatic cancer. Mol Cancer Res; 14(11); 1124-35. ©2016 AACR.

Tackling Cancer Stem Cells via Inhibition of EMT Transcription Factors

Cancer stem cell (CSC) has become recognized for its role in both tumorigenesis and poor patient prognosis in recent years. Traditional therapeutics are unable to effectively eliminate this group of cells from the bulk population of cancer cells, allowing CSCs to persist posttreatment and thus propagate into secondary tumors. The therapeutic potential of eliminating CSCs, to decrease tumor relapse, has created a demand for identifying mechanisms that directly target and eliminate cancer stem cells. Molecular profiling has shown that cancer cells and tumors that exhibit the CSC phenotype also express genes associated with the epithelial-to-mesenchymal transition (EMT) feature. Ample evidence has demonstrated that upregulation of master transcription factors (TFs) accounting for the EMT process such as Snail/Slug and Twist can reprogram cancer cells from differentiated to stem-like status. Despite being appealing therapeutic targets for tackling CSCs, pharmacological approaches that directly target EMT-TFs remain impossible. In this review, we will summarize recent advances in the regulation of Snail/Slug and Twist at transcriptional, translational, and posttranslational levels and discuss the clinical implication and application for EMT blockade as a promising strategy for CSC targeting.

Molecular signatures of mu opioid receptor and somatostatin receptor 2 in pancreatic cancer

Pancreatic ductal adenocarcinoma (PDAC), a particularly aggressive malignancy, has been linked to atypical levels, certain mutations, and aberrant signaling of G-protein-coupled receptors (GPCRs). GPCRs have been challenging to target in cancer because they organize into complex networks in tumor cells. To dissect such networks with nanometer-scale precision, here we combine traditional biochemical approaches with superresolution microscopy methods. A novel interaction specific to PDAC is identified between mu opioid receptor (MOR) and somatostatin receptor 2 (SSTR2). Although MOR and SSTR2 did not colocalize in healthy pancreatic cells or matching healthy patient tissues, the pair did significantly colocalize in pancreatic cancer cells, multicellular tumor spheroids, and cancerous patient tissues. Moreover, this association in pancreatic cancer cells correlated with functional cross-talk and increased metastatic potential of cells. Coactivation of MOR and SSTR2 in PDAC cells led to increased expression of mesenchymal markers and decreased expression of an epithelial marker. Together these results suggest that the MOR-SSTR2 heteromer may constitute a novel therapeutic target for PDAC.