RUNX3 Controls a Metastatic Switch in Pancreatic Ductal Adenocarcinoma

Molecular targets regulating invasion and metastasis of pancreatic cancer

Pancreatic cancer is one of the most malignant tumors of the digestive system. Invasion and metastasis are important biological characteristics of pancreatic cancer and contribute greatly to the poor prognosis of the patients. Many lines of evidence have recently revealed that many molecules, genes and proteins regulate the invasion and metastasis of pancreatic cancer cells. Therefore, exploration and a deep understanding of the molecular mechanism accounting for the invasion and metastasis of pancreatic cancer can help find novel pancreatic cancer biomarkers, improve early diagnosis, develop novel and effective treatment strategies, and predict the prognosis. This review summarizes the latest progress in the research of molecular targets for pancreatic cancer and the mechanisms by which they participate in the invasion and metastasis of this aggressive malignancy.

Prognostic stratification of resected pancreatic ductal adenocarcinoma: Past, present, and future

Pancreatic ductal adenocarcinoma (PDAC) is the digestive cancer with the poorest prognosis, with a 5-year overall survival rate of 7%. Complete surgical resection followed by adjuvant chemotherapy is the only treatment with curative intent. However, many patients with an apparently localized disease who may undergo primary tumor resection already have micro-metastatic disease and will promptly develop metastases. Considering the significant rate of morbidity and mortality upon pancreatic surgery, the pre-operative identification of patients with an aggressive disease is therefore a major clinical issue. Although tumor size, differentiation, margins, and lymph node invasion are the main "classical" prognostic factors, they are not sufficient to fully predict early disease recurrence. In the last decade, multi-omics high-throughput analyses have provided a new insight into PDAC biology and have led to the description of multiple molecular subtypes, with a significant prognostic value for most of them, but that have not yet been transposed to routine clinical practice, mainly due to poor availability of tumor tissue material prior to surgical resection. In this review, we provide an overview of the current status of clinico-pathological and molecular biomarkers (tumor and blood) to predict early recurrence, and their implications for clinical practice and future research development.

Hmga2 is dispensable for pancreatic cancer development, metastasis, and therapy resistance

Expression of the chromatin-associated protein HMGA2 correlates with progression, metastasis and therapy resistance in pancreatic ductal adenocarcinoma (PDAC). Hmga2 has also been identified as a marker of a transient subpopulation of PDAC cells that has increased metastatic ability. Here, we characterize the requirement for Hmga2 during growth, dissemination, and metastasis of PDAC in vivo using conditional inactivation of Hmga2 in well-established autochthonous mouse models of PDAC. Overall survival, primary tumour burden, presence of disseminated tumour cells in the peritoneal cavity or circulating tumour cells in the blood, and presence and number of metastases were not significantly different between mice with Hmga2-wildtype or Hmga2-deficient tumours. Treatment of mice with Hmga2-wildtype and Hmga2-deficient tumours with gemcitabine did not uncover a significant impact of Hmga2-deficiency on gemcitabine sensitivity. Hmga1 and Hmga2 overlap in their expression in both human and murine PDAC, however knockdown of Hmga1 in Hmga2-deficient cancer cells also did not decrease metastatic ability. Thus, Hmga2 remains a prognostic marker which identifies a metastatic cancer cell state in primary PDAC, however Hmga2 has limited if any direct functional impact on PDAC progression and therapy resistance.

Pre-neoplastic pancreas cells enter a partially mesenchymal state following transient TGF-β exposure

Pancreatic ductal adenocarcinoma (PDAC) is a deadly disease and a major health problem in the United States. While the cytokine TGF-β has been implicated in PDAC development, it can exert both pro-tumorigenic and anti-tumorigenic effects that are highly context dependent and incompletely understood. Using three-dimensional (3D) cultures of KrasG12D-expressing mouse pancreatic epithelial cells we demonstrated that while exposure to exogenous TGF-β induced growth arrest of the KrasG12D cells, its subsequent removal allowed the cells to enter a hyper-proliferative, partially mesenchymal (PM), and progenitor-like state. This state was highly stable and was maintained by autocrine TGF-β signaling. While untreated KrasG12D cells formed cystic lesions in vivo, PM cells formed ductal structures resembling human PanINs, suggesting that they had attained increased oncogenic potential. Supporting this hypothesis, we determined that the PM cells share salient molecular and phenotypic features with the quasi-mesenchymal/squamous subtype of human PDAC, which has the worst prognosis of any of the recently identified subtypes. Transient pulses of TGF-β have been observed during pancreatitis, a major risk factor for PDAC. Our data suggest that transient TGF-β exposure is sufficient to induce the acquisition of stable PDAC-associated phenotypes in pre-neoplastic KrasG12D cells, providing novel molecular insight into the complex role of TGF-β in tumorigenesis.

Tumor microenvironment participates in metastasis of pancreatic cancer

Pancreatic cancer is a deadly disease with high mortality due to difficulties in its early diagnosis and metastasis. The tumor microenvironment induced by interactions between pancreatic epithelial/cancer cells and stromal cells is critical for pancreatic cancer progression and has been implicated in the failure of chemotherapy, radiation therapy and immunotherapy. Microenvironment formation requires interactions between pancreatic cancer cells and stromal cells. Components of the pancreatic cancer microenvironment that contribute to desmoplasia and immunosuppression are associated with poor patient prognosis. These components can facilitate desmoplasia and immunosuppression in primary and metastatic sites or can promote metastasis by stimulating angiogenesis/lymphangiogenesis, epithelial-mesenchymal transition, invasion/migration, and pre-metastatic niche formation. Some molecules participate in both microenvironment formation and metastasis. In this review, we focus on the mechanisms of pancreatic cancer microenvironment formation and discuss how the pancreatic cancer microenvironment participates in metastasis, representing a potential target for combination therapy to enhance overall survival.

Glycemic Variability Promotes Both Local Invasion and Metastatic Colonization by Pancreatic Ductal Adenocarcinoma

Background & Aims

Although nearly half of pancreatic ductal adenocarcinoma (PDAC) patients have diabetes mellitus with episodes of hyperglycemia, its tumor microenvironment is hypoglycemic. Thus, it is crucial for PDAC cells to develop adaptive mechanisms dealing with oscillating glucose levels. So far, the biological impact of such glycemic variability on PDAC biology remains unknown.

Methods

Murine PDAC cells were cultured in low- and high-glucose medium to investigate the molecular, biochemical, and metabolic influence of glycemic variability on tumor behavior. A set of in vivo functional assays including orthotopic implantation and portal and tail vein injection were used. Results were further confirmed on tissues from PDAC patients.

Results

Glycemic variability has no significant effect on PDAC cell proliferation. Hypoglycemia is associated with local invasion and angiogenesis, whereas hyperglycemia promotes metastatic colonization. Increased metastatic colonization under hyperglycemia is due to increased expression of runt related transcription factor 3 (Runx3), which further activates expression of collagen, type VI, alpha 1 (Col6a1), forming a glycemic pro-metastatic pathway. Through epigenetic machinery, retinoic acid receptor beta (Rarb) expression fluctuates according to glycemic variability, acting as a critical sensor relaying the glycemic signal to Runx3/Col6a1. Moreover, the signal axis of Rarb/Runx3/Col6a1 is pharmaceutically accessible to a widely used antidiabetic substance, metformin, and Rar modulator. Finally, PDAC tissues from patients with diabetes show an increased expression of COL6A1.

Conclusions

Glycemic variability promotes both local invasion and metastatic colonization of PDAC. A pro-metastatic signal axis Rarb/Runx3/Col6a1 whose activity is controlled by glycemic variability is identified. The therapeutic relevance of this pathway needs to be explored in PDAC patients, especially in those with diabetes.

Intracellular and extracellular TGF-β signaling in cancer: some recent topics

Transforming growth factor (TGF)-β regulates a wide variety of cellular responses, including cell growth arrest, apoptosis, cell differentiation, motility, invasion, extracellular matrix production, tissue fibrosis, angiogenesis, and immune function. Although tumor-suppressive roles of TGF-β have been extensively studied and well-characterized in many cancers, especially at early stages, accumulating evidence has revealed the critical roles of TGF-β as a pro-tumorigenic factor in various types of cancer. This review will focus on recent findings regarding epithelial-mesenchymal transition (EMT) induced by TGF-β, in relation to crosstalk with some other signaling pathways, and the roles of TGF-β in lung and pancreatic cancers, in which TGF-β has been shown to be involved in cancer progression. Recent findings also strongly suggested that targeting TGF-β signaling using specific inhibitors may be useful for the treatment of some cancers. TGF-β plays a pivotal role in the differentiation and function of regulatory T cells (Tregs). TGF-β is produced as latent high molecular weight complexes, and the latent TGF-β complex expressed on the surface of Tregs contains glycoprotein A repetitions predominant (GARP, also known as leucine-rich repeat containing 32 or LRRC32). Inhibition of the TGF-β activities through regulation of the latent TGF-β complex activation will be discussed.

Advances in the Genetics and Biology of Pancreatic Cancer

Pancreatic ductal adenocarcinoma (PDA) remains one of the most devastating diagnoses in modern medicine. While the clinical management of the disease has improved, the complex biologic underpinnings of PDA enable both its aggressive nature and slow clinical translational progress. In this review, we provide an overview of the key features of PDA genetics and biology, highlighting translational challenges and providing a framework for improved diagnostic and therapeutic approaches.

Understanding Disease Biology and Informing the Management of Pancreas Cancer With Preclinical Model Systems

Recent advances in cytotoxic therapies for pancreatic ductal adenocarcinoma (PDA) are overshadowed by stalled clinical progress of more targeted strategies, the vast majority of which have failed in clinical trials. Inability to translate preclinical promise into clinical efficacy derives, in part, from imperfect disease modeling and mismatches between preclinical and clinical study design and execution. Into these gaps fall our patients who enter the clinical trial landscape expectantly and bear the brunt of its inadequacies. If improving patient survival is paramount, then it must be acknowledged that the failure of a phase III trial represents a larger failure of all of the work that preceded it. Repeated failures suggest a need to reappraise the current preclinical-to-clinical apparatus. Exceptional models of PDA are now available to researchers, and the first steps toward a new era of success can begin with improved selection and application of these systems. We discuss the key features of the major preclinical platforms for PDA and propose a paradigm for rigorous interrogation of prospective therapies.

Treatment of pancreatic head cancer with obstructive jaundice by endoscopy ultrasonography-guided gastrojejunostomy: A case report and literature review

RATIONALE

Ultrasonography-guided gastrojejunostomy (EUS-GJ) might be a safe, innovative and minimally invasive interventional treatment for patients with gastric outlet obstruction (GOO) as an alternative to the surgical approach. To date, few cases have been reported in the literature.

PATIENT CONCERNS

A case of pancreatic head carcinoma with obstructive jaundice occurred in a 78-year-old man with a prior history of pancreatic head cancer. Biliary stent placement was conducted 1 year earlier.

DIAGNOSES

The patient was diagnosed with pancreatic cancer, pulmonary infection, pyloric obstruction, and biliary stent implantation.

INTERVENTIONS

EUS-GJ was performed. The wire and a double-balloon catheter reached the position of stenosis, then a double mushroom head bracket was released under EUS. The position was confirmed via X-ray.

OUTCOMES

The symptoms of obstruction were alleviated. No recurrence of obstruction, bleeding, perforation, and other complications occurred for the following 1.5 months while he died because of whole body spread of pancreatic cancer.

LESSONS

EUS-GJ may be reliable and effective for patients with GOO.

RUNX3 as a Potential Predictor of Metastasis in Human Pancreatic Cancer

BACKGROUND/AIM

In genetically engineered murine models of pancreatic ductal adenocarcinomas (PDAC), high levels of Runx3 increase the metastatic potential of cancer cells. In this study we evaluated the role of Runx3 in human pancreatic cancer.

MATERIALS AND METHODS

Runx3 was retrospectively assessed by immunohistochemistry in seventy-eight tumor samples of patients who underwent surgical resection for PDCA and were followed at least for 24 months.

RESULTS

Thirty-two cases resulted completely negative for Runx3; forty-six showed highly variable expression. We established an optimal cut-off value of Runx3 in predicting distant metastasis equal to 0.04. The odds ratio (ORs) for development of distant metastases at multivariate analysis for patients having Runx3 ≥0.04 was 4.26 (p=0.043) and 4.68 (p=0.032) after adjusting for residual tumor and treatment, respectively; OR for development of metastases in multiple sites was 4.28 (p=0.025) for Runx3 ≥0.04.

CONCLUSION

Our results support the ability of Runx3 to contribute to the dissemination of human PDAC thus confirming the observations from murine models.

Genetically Engineered Mouse Models of K-Ras-Driven Lung and Pancreatic Tumors: Validation of Therapeutic Targets

K-RAS signaling has been intensely studied for over 40 years. Yet, as of today, no drugs have been approved to treat K-RAS mutant cancers. Since the turn of the century, scientists have used genetically engineered mouse (GEM) models to reproduce K-RAS mutant cancers in a laboratory setting to elucidate those molecular events responsible for the onset and progression of these tumors and to identify suitable therapies. In this review, we outline a brief description of available GEM models for two tumor types known to be driven by K-RAS mutations: lung adenocarcinoma and pancreatic ductal adenocarcinoma. In addition, we summarize a series of studies that have used these GEM tumor models to validate, either by genetic or pharmacological approaches, the therapeutic potential of a variety of targets, with the ultimate goal of translating these results to the clinical setting.

SMAD4 Gene Mutation Renders Pancreatic Cancer Resistance to Radiotherapy through Promotion of Autophagy

Purpose: Understanding the mechanism of radioresistance could help develop strategies to improve therapeutic response of patients with PDAC. The SMAD4 gene is frequently mutated in pancreatic cancer. In this study, we investigated the role of SMAD4 deficiency in pancreatic cancer cells' response to radiotherapy.Experimental Design: We downregulated SMAD4 expression with SMAD4 siRNA or SMAD4 shRNA and overexpressed SMAD4 in SMAD4 mutant pancreatic cancer cells followed by clonogenic survival assay to evaluate their effects on cell radioresistance. To study the mechanism of radioresistance, the effects of SMAD4 loss on reactive oxygen species (ROS) and autophagy were determined by flow cytometry and immunoblot analysis, respectively. Furthermore, we measured radioresistance by clonogenic survival assay after treatment with autophagy inhibitor (Chloroquine) and ROS inhibitor (N-acetyl-l-cysteine) in SMAD4-depleted pancreatic cancer cells. Finally, the effects of SMAD4 on radioresistance were also confirmed in an orthotopic tumor model derived from SMAD4-depleted Panc-1 cells.Results:SMAD4-depleted pancreatic cancer cells were more resistant to radiotherapy based on clonogenic survival assay. Overexpression of wild-type SMAD4 in SMAD4-mutant cells rescued their radiosensitivity. Radioresistance mediated by SMAD4 depletion was associated with persistently higher levels of ROS and radiation-induced autophagy. Finally, SMAD4 depletion induced in vivo radioresistance in Panc-1-derived orthotopic tumor model (P = 0.038). More interestingly, we observed that the protein level of SMAD4 is inversely correlated with autophagy in orthotopic tumor tissue samples.Conclusions: Our results demonstrate that defective SMAD4 is responsible for radioresistance in pancreatic cancer through induction of ROS and increased level of radiation-induced autophagy. Clin Cancer Res; 24(13); 3176-85. ©2018 AACR.

Loss of KDM6A Activates Super-Enhancers to Induce Gender-Specific Squamous-like Pancreatic Cancer and Confers Sensitivity to BET Inhibitors

KDM6A, an X chromosome-encoded histone demethylase and member of the COMPASS-like complex, is frequently mutated in a broad spectrum of malignancies and contributes to oncogenesis with poorly characterized mechanisms. We found that KDM6A loss induced squamous-like, metastatic pancreatic cancer selectively in females through deregulation of the COMPASS-like complex and aberrant activation of super-enhancers regulating ΔNp63, MYC, and RUNX3 oncogenes. This subtype of tumor developed in males had concomitant loss of UTY and KDM6A, suggesting overlapping roles, and points to largely demethylase independent tumor suppressor functions. We also demonstrate that KDM6A-deficient pancreatic cancer is selectively sensitive to BET inhibitors, which reversed squamous differentiation and restrained tumor growth in vivo, highlighting a therapeutic niche for patient tailored therapies.

The evolution into personalized therapies in pancreatic ductal adenocarcinoma: challenges and opportunities

INTRODUCTION

Pancreatic ductal adenocarcinoma (PDAC) is projected to be the second leading cause of cancer related mortality in the United States in 2030, with a 5-year overall survival of less than 10% despite decades of extensive research. Pancreatic cancer is marked by the accumulation of complex molecular changes, complex tumor-stroma interaction, and an immunosuppressive tumor microenvironment. PDAC has proven to be resistant to many cytotoxic, targeted and immunologic treatment approaches. Areas covered: In this paper, we review the major areas of research in PDAC, with highlights on the challenges and areas of opportunity for personalized treatment approaches. Expert commentary: The focus of research in pancreatic cancer has moved away from developing conventional cytotoxic combinations. The marked advances in understanding the molecular biology of this disease especially in the areas of the microenvironment, metabolism, and DNA repair have opened new opportunities for developing novel treatment strategies. Improved understanding of molecular abnormalities allows the development of personalized treatment approaches.

Functional Analyses of RUNX3 and CaMKIINα in Ovarian Cancer Cell Lines Reveal Tumor-Suppressive Functions for CaMKIINα and Dichotomous Roles for RUNX3 Transcript Variants

(1) Background: Epithelial ovarian cancer (EOC) is the most lethal cancer of the female reproductive system. In an earlier study, we identified multiple genes as hypermethylated in tumors of patients with poor prognosis. The most promising combination of markers to predict a patient’s outcome was CaMKIINα and RUNX3. Aim of this study was to functionally validate the importance of both genes. (2) Methods: IC₅₀ measurements, cell cycle distribution-, proliferation, and migration experiments were conducted after transgene overexpression in two EOC cell lines. (3) Results: We showed that CaMKIINα has tumor suppressive functions in vitro and reduces proliferation, migration, and colony formation. However, it had no effect on the reversion of the resistance to cisplatin. RUNX3 exhibited dualistic functions related to cisplatin sensitivity and migration capacity, depending on the respective transcript variant (TV). A2780 cells expressing RUNX3 TV2—the promoter of which harbors a CpG (5′-C-phosphate-G-3′) island and is potentially inactivated by hypermethylation—exhibited increased cisplatin sensitivity and reduced migration properties. However, RUNX3 TV1, not affected by CpG island methylation could be characterized as mediating resistance and enhancing migration in A2780. The higher resistance of RUNX3 TV1 transfected cells correlates with a reduction of cell proliferation. Moreover, RUNX3 TV1 expressing cells exhibit a reduced cell cycle arrest at the gap-2 or mitosis phase (G2/M) under cisplatin treatment comparable to resistant A2780 subcultures. (4) Conclusion: It appears that CaMKIINα and RUNX3 TV2 can reduce the malignant potential of EOC cells.

Characterization of RON protein isoforms in pancreatic cancer: implications for biology and therapeutics

The RON tyrosine kinase receptor is under investigation as a novel target in pancreatic cancer. While RON mutations are uncommon, RON isoforms are produced in cancer cells via a variety of mechanisms. In this study we sought to: 1) characterize RON isoform expression in pancreatic cancer, 2) investigate mechanisms that regulate isoform expression, and 3) determine how various isoforms effect gene expression, oncogenic phenotypes and responses to RON directed therapies. We quantified RON transcripts in human pancreatic cancer and found expression levels 2500 fold that of normal pancreas with RON isoform expression comprising nearly 50% of total transcript. RNA seq studies revealed that the short form (sfRON) and P5P6 isoforms which have ligand independent activity, induce markedly different patterns of gene expression than wild type RON. We found that transcription of RON isoforms is regulated by promoter hypermethylation as the DNA demethylating agent 5-aza-2′-deoxycytidine decreased all RON transcripts in a subset of pancreatic cancer cell lines. The viability of sfRON-expressing HPDE cells was reduced by a RON specific small molecule inhibitor, while a therapeutic monoclonal antibody had no demonstrable effects. In summary, RON isoforms may comprise half of total RON transcript in human pancreatic cancer and their expression is regulated at least in part by promoter hypermethylation. RON isoforms activate distinct patterns of gene expression, have transforming activity and differential responses to RON directed therapies. These findings further our understanding of RON biology in pancreatic cancer and have implications for therapeutic strategies to target RON activity.

A genetic roadmap of pancreatic cancer: still evolving

A diagnosis of pancreatic ductal adenocarcinoma (PDA) is often fatal. PDA is widely recognised as one of the 'incurable cancers' because therapies against this tumour type are generally ineffective. The fatal nature of this tumour is due to its aggressive clinical course. Pancreatic cancer commonly presents at the metastatic stage; even in cases where tumours are localised to the pancreas at diagnosis, metastatic seeds have often been invariably been spawned off, frustrating surgical attempts to cure the cancer. The key principles of pancreatic cancer mutational development were outlined nearly two decades ago using the genetics of precursor lesions to position the various stages of tumour progression. Since then, there has been a cavalcade of new data. How these recent studies impact the classical perceptions of pancreatic cancer development is a work in progress. Given that significant improvements in patient outcomes are not in sight for this disease, it is likely that broadening the current perspectives and acquiring deeper biological insights into the morphogenetic route of tumour development will be needed to foster new strategies for more effective cancer control.

Pancreatic Cancer: Molecular Characterization, Clonal Evolution and Cancer Stem Cells

Pancreatic Ductal Adenocarcinoma (PDAC) is the fourth most common cause of cancer-related death and is the most lethal of common malignancies with a five-year survival rate of <10%. PDAC arises from different types of non-invasive precursor lesions: intraductal papillary mucinous neoplasms, mucinous cystic neoplasms and pancreatic intraepithelial neoplasia. The genetic landscape of PDAC is characterized by the presence of four frequently-mutated genes: KRAS, CDKN2A, TP53 and SMAD4. The development of mouse models of PDAC has greatly contributed to the understanding of the molecular and cellular mechanisms through which driver genes contribute to pancreatic cancer development. Particularly, oncogenic KRAS-driven genetically-engineered mouse models that phenotypically and genetically recapitulate human pancreatic cancer have clarified the mechanisms through which various mutated genes act in neoplasia induction and progression and have led to identifying the possible cellular origin of these neoplasias. Patient-derived xenografts are increasingly used for preclinical studies and for the development of personalized medicine strategies. The studies of the purification and characterization of pancreatic cancer stem cells have suggested that a minority cell population is responsible for initiation and maintenance of pancreatic adenocarcinomas. The study of these cells could contribute to the identification and clinical development of more efficacious drug treatments.

Survival of pancreatic cancer cells lacking KRAS function

Activating mutations in the proto-oncogene KRAS are a hallmark of pancreatic ductal adenocarcinoma (PDAC), an aggressive malignancy with few effective therapeutic options. Despite efforts to develop KRAS-targeted drugs, the absolute dependence of PDAC cells on KRAS remains incompletely understood. Here we model complete KRAS inhibition using CRISPR/Cas-mediated genome editing and demonstrate that KRAS is dispensable in a subset of human and mouse PDAC cells. Remarkably, nearly all KRAS deficient cells exhibit phosphoinositide 3-kinase (PI3K)-dependent mitogen-activated protein kinase (MAPK) signaling and induced sensitivity to PI3K inhibitors. Furthermore, comparison of gene expression profiles of PDAC cells retaining or lacking KRAS reveal a role of KRAS in the suppression of metastasis-related genes. Collectively, these data underscore the potential for PDAC resistance to even the very best KRAS inhibitors and provide insights into mechanisms of response and resistance to KRAS inhibition.

Pancreatic cancer cells may develop resistance to KRAS inhibitors due to activation of compensatory pathways. In this study, the authors demonstrate that KRAS is dispensable in a subset of pancreatic cancer and that PI3K signalling may have an important role in mediating tumor growth following KRAS inhibition.

Roles of RUNX in Solid Tumors

All RUNX genes have been implicated in the development of solid tumors, but the role each RUNX gene plays in the different tumor types is complicated by multiple interactions with major signaling pathways and tumor heterogeneity. Moreover, for a given tissue type, the specific role of each RUNX protein is distinct at different stages of differentiation. A regulatory function for RUNX in tissue stem cells points sharply to a causal effect in tumorigenesis. Understanding how RUNX dysregulation in cancer impinges on normal biological processes is important for identifying the molecular mechanisms that lead to malignancy. It will also indicate whether restoration of proper RUNX function to redirect cell fate is a feasible treatment for cancer. With the recent advances in RUNX research, it is time to revisit the many mechanisms/pathways that RUNX engage to regulate cell fate and decide whether cells proliferate, differentiate or die.

Reprogramming Enhancers to Drive Metastasis

Acquired molecular changes can promote the spreading of primary tumor cells to distant tissues. In this issue of Cell, Roe et al. show that metastatic progression of pancreatic cancer involves large-scale enhancer reprogramming by Foxa1, which activates transcriptional program specifying early endodermal stem cells.

PDAC-derived exosomes enrich the microenvironment in MDSCs in a SMAD4-dependent manner through a new calcium related axis

Tumor genetics and escape from immune surveillance concur in the poor prognosis of PDAC. In this study an experimental model was set up to verify whether SMAD4, deleted in about 55% PDAC and associated with poor prognosis, is involved in determining immunosuppression through Exosomes (Exo). Potential mechanisms and mediators underlying SMAD4-dependent immunosuppression were evaluated by studying intracellular calcium (Fluo-4), Exo-miRNAs (microarray) and Exo-proteins (SILAC). Two PDAC cell lines expressing (BxPC3-SMAD4+) or not-expressing (BxPC3) SMAD4 were used to prepare Exo-enriched conditioned media, employed in experiments with blood donors PBMCs. Exo expanded myeloid derived suppressor cells (gMDSC and mMDSC, flow cytometry) and altered intracellular calcium fluxes in an SMAD4 dependent manner. BxPC3-SMAD4+, but mainly BxPC3 Exo, increased calcium fluxes of PBMCs (p = 0.007) and this increased intracellular calcium trafficking characterized mMDSCs. The analysis of de-regulated Exo-miRNAs and transfection experiments revealed hsa-miR-494-3p and has-miR-1260a as potential mediators of SMAD4-associated de-regulated calcium fluxes. Eleven main biological processes were identified by the analysis of SMAD4-associated de-regulated Exo-proteins, including translation, cell adhesion, cell signaling and glycolysis. A reverse Warburg effect was observed by treating PBMCs with PDAC-derived Exo: BxPC3 Exo induced a higher glucose consumption and lactate production than BxPC3-SMAD4+ Exo. Conclusion: PDAC-derived Exo from cells with, but mainly from those without SMAD4 expression, create an immunosuppressive myeloid cell background by increasing calcium fluxes and glycolysis through the transfer of SMAD4-related differentially expressed miRNAs and proteins.

Combination immunohistochemistry for SMAD4 and Runt-related transcription factor 3 may identify a favorable prognostic subgroup of pancreatic ductal adenocarcinomas

Purposes

SMAD4/DPC4 mutations have been associated with aggressive behavior in pancreatic ductal adenocarcinomas (PDAC), and it has recently been suggested that RUNX3 expression combined with SMAD4 status may predict the metastatic potential of PDACs. We evaluated the prognostic utility of SMAD4/RUNX3 status in human PDACs by immunohistochemistry.

Materials and Methods

Immunohistochemical stains were performed for SMAD4 and RUNX3 on 210 surgically resected PDACs, and the results were correlated with the clinicopathological features.

Results

Loss of SMAD4 expression was associated with poor overall survival (OS) (p = 0.015) and progression-free survival (PFS) (p = 0.044). Nuclear RUNX3 expression was associated with decreased OS (p = 0.010) and PFS (p = 0.009), and more frequent in poorly differentiated PDACs (p = 0.037). On combining RUNX3/SMAD4 status, RUNX3-/SMAD4+ PDACs demonstrated longer OS (p = 0.008, median time; RUNX3-/SMAD4+ 34 months, others 17 months) and PFS (p = 0.009, median time; RUNX3-/SMAD4+ 29 months, others 8 months) compared to RUNX3+/SMAD4+ and SMAD4- groups; RUNX3-/SMAD4+ was a significant independent predictive factor for both OS [p = 0.025, HR 1.842 (95% CI 1.079-3.143)] and PFS [p = 0.020, HR 1.850 (95% CI 1.100-3.113)].

Conclusions

SMAD4-positivity with RUNX3-negativity was a significant independent predictive factor for favorable OS and PFS in PDAC. This is the first and large clinicopathological study of RUNX3/SMAD4 expression status in human PDAC. Combination immunohistochemistry for SMAD4 and RUNX3 may help identify a favorable prognostic subgroup of PDAC.

Acinar-to-Ductal Metaplasia Induced by Transforming Growth Factor Beta Facilitates KRASG12D-driven Pancreatic Tumorigenesis

BACKGROUND & AIMS

Transforming growth factor beta (TGFβ) acts either as a tumor suppressor or as an oncogene, depending on the cellular context and time of activation. TGFβ activates the canonical SMAD pathway through its interaction with the serine/threonine kinase type I and II heterotetrameric receptors. Previous studies investigating TGFβ-mediated signaling in the pancreas relied either on loss-of-function approaches or on ligand overexpression, and its effects on acinar cells have so far remained elusive.

METHODS

We developed a transgenic mouse model allowing tamoxifen-inducible and Cre-mediated conditional activation of a constitutively active type I TGFβ receptor (TβRICA) in the pancreatic acinar compartment.

RESULTS

We observed that TβRICA expression induced acinar-to-ductal metaplasia (ADM) reprogramming, eventually facilitating the onset of KRASG12D-induced pre-cancerous pancreatic intraepithelial neoplasia. This phenotype was characterized by the cellular activation of apoptosis and dedifferentiation, two hallmarks of ADM, whereas at the molecular level, we evidenced a modulation in the expression of transcription factors such as Hnf1β, Sox9, and Hes1.

CONCLUSIONS

We demonstrate that TGFβ pathway activation plays a crucial role in pancreatic tumor initiation through its capacity to induce ADM, providing a favorable environment for KRASG12D-dependent carcinogenesis. Such findings are highly relevant for the development of early detection markers and of potentially novel treatments for pancreatic cancer patients.

Runx3 plays a critical role in restriction-point and defense against cellular transformation

The restriction (R)-point decision is fundamental to normal differentiation and the G₁-S transition, and the decision-making machinery is perturbed in nearly all cancer cells. The mechanisms underlying the cellular context-dependent R-point decision remain poorly understood. We found that the R-point was dysregulated in Runx3^-/-mouse embryonic fibroblasts (MEFs), which formed tumors in nude mice. Ectopic expression of Runx3 restored the R-point and abolished the tumorigenicity of Runx3^-/-MEFs and K-Ras-activated Runx3^-/-MEFs (Runx3^-/-;K-Ras^G12D/+). During the R-point, Runx3 transiently formed a complex with pRb and Brd2 and induced Cdkn1a (p21^{Waf1/Cip1/Sdi1}; p21), a key regulator of the R-point transition. Cyclin D-CDK4/6 promoted dissociation of the pRb-Runx3-Brd2 complex, thus turning off p21 expression. However, cells harboring oncogenic K-Ras maintained the pRb-Runx3-Brd2 complex and p21 expression even after introduction of Cyclin D1. Thus, Runx3 plays a critical role in R-point regulation and defense against cellular transformation.

RUNX1 promote invasiveness in pancreatic ductal adenocarcinoma through regulating miR-93

Runt-related transcription factor 1(RUNX1), a key factor in hematopoiesis that mediates specification and homeostasis of hematopoietic stem and progenitor cells (HSPCs), is also overexpressed in several solid human cancers, and correlated with tumor progression. However, the expression and function of RUNX1 in pancreatic ductal adenocarcinoma were still unclear. Here, we show that RUNX1 is highly expressed in pancreatic adenocarcinoma tissues and knocking down of RUNX1 attenuated aggressiveness in pancreatic cell lines. Moreover, we found that RUNX1 could negatively regulate the expression of miR-93. Bioinformatics method showed that there are two binding sites in the the promotor region of miR-93 precursor and through ChIP-qPCR and firefly luciferase reporter assay, we vertified that these two binding sites each have transcriptive activity in one pancreatic cell lines. This result supported our presumption that RUNX1 regulate miR-93 through binding to the promotor region of miR-93. Besides, the expression and function of miR-93 is quite the opposite, miR-93 overexpression suppresses migration and invasiveness in pancreatic cell lines supporting that RUNX1 negatively regulated miR-93. Our findings provided evidence regarding the role of RUNX1 as an oncogene through the inhibition of miR-93. Targeting RUNX1 can be a potential therapeutic strategy in pancreatic cancer.

Clinicopathological significance of SMAD4 loss in pancreatic ductal adenocarcinomas: a systematic review and meta-analysis

Pancreatic ductal adenocarcinoma (PDAC) is one of the leading causes of cancer mortality. Although advances have been made in understanding the pathogenesis of PDAC, the outcome still remains poor. The aim of this study is to conduct a meta-analysis to evaluate the precise association between SMAD4 loss and clinicopathological significance in PDAC. A literature search was made in PubMed, Web of Science, Google scholar, and EMBASE for related publications. The data were extracted and assessed by two reviewers independently. Analysis of pooled data was performed, Odds Ratio or Hazard Ratio with corresponding confidence intervals was calculated and summarized. 12 relevant articles were included for full review in detail and meta-analysis. The frequency of SMAD4 protein loss was significantly increased in PDAC than in nonmalignant pancreatic tissue, Odd Ratio was 0.05 with 95% confidence interval 0.01-0.23, p<0.0001. SMAD4 loss was significantly associated with poor overall survival in patients with PDAC, Hazard Ratio was 0.61 with 95% confidence interval 0.38-0.99, p=0.05. SMAD4 loss was not correlated with the size, grades, and lymph node metastasis of PDAC. In conclusion, SMAD4 is a biomarker for the diagnosis of PDAC. SMAD4 loss is significantly related to poor prognosis in patients with PDAC.

BLIMP1 Induces Transient Metastatic Heterogeneity in Pancreatic Cancer

Pancreatic ductal adenocarcinoma (PDAC) is one of the most metastatic and deadly cancers. Despite the clinical significance of metastatic spread, our understanding of molecular mechanisms that drive PDAC metastatic ability remains limited. By generating a genetically engineered mouse model of human PDAC, we uncover a transient subpopulation of cancer cells with exceptionally high metastatic ability. Global gene expression profiling and functional analyses uncovered the transcription factor BLIMP1 as a driver of PDAC metastasis. The highly metastatic PDAC subpopulation is enriched for hypoxia-induced genes, and hypoxia-mediated induction of BLIMP1 contributes to the regulation of a subset of hypoxia-associated gene expression programs. These findings support a model in which upregulation of BLIMP1 links microenvironmental cues to a metastatic stem cell character.Significance: PDAC is an almost uniformly lethal cancer, largely due to its tendency for metastasis. We define a highly metastatic subpopulation of cancer cells, uncover a key transcriptional regulator of metastatic ability, and define hypoxia as an important factor within the tumor microenvironment that increases metastatic proclivity. Cancer Discov; 7(10); 1184-99. ©2017 AACR.See related commentary by Vakoc and Tuveson, p. 1067This article is highlighted in the In This Issue feature, p. 1047.

Enhancer Reprogramming Promotes Pancreatic Cancer Metastasis

Pancreatic ductal adenocarcinoma (PDA) is one of the most lethal human malignancies, owing in part to its propensity for metastasis. Here, we used an organoid culture system to investigate how transcription and the enhancer landscape become altered during discrete stages of disease progression in a PDA mouse model. This approach revealed that the metastatic transition is accompanied by massive and recurrent alterations in enhancer activity. We implicate the pioneer factor FOXA1 as a driver of enhancer activation in this system, a mechanism that renders PDA cells more invasive and less anchorage-dependent for growth in vitro, as well as more metastatic in vivo. In this context, FOXA1-dependent enhancer reprogramming activates a transcriptional program of embryonic foregut endoderm. Collectively, our study implicates enhancer reprogramming, FOXA1 upregulation, and a retrograde developmental transition in PDA metastasis.

UnPAKing RUNX3 functions-Both sides of the coin

Post translational modifications of RUNX3 have been shown to play an important role in directing RUNX3 functions. In this review we highlight the phosphorylation dependent functions of RUNX3 as regulated by PAK1 and its implications on tumorigenesis.

The Role of Consolidation Chemoradiotherapy in Locally Advanced Pancreatic Cancer Receiving Chemotherapy: An Updated Systematic Review and Meta-Analysis

Purpose

The role of consolidation chemoradiation (CCRT) after systemic chemotherapy in locally advanced pancreatic cancer (LAPC) is still controversial. We aim to evaluate the effectiveness of CCRT in LAPC using systematic review and meta-analysis of prospective studies.

Materials and Methods

Prospective clinical trials of LAPC receiving chemotherapy with or without subsequent CCRT were included in the analysis. We systematically searched in PubMed, MEDLINE, Embase, and Web of Science. The primary outcome of interest was 1-year survival. Secondary endpoints were median overall survival, progression-free survival, toxicity, and resection rate.

Results

Forty-one studies with 49 study arms were included with a total of 1,018 patients receiving CCRT after induction chemotherapy (ICT) and 954 patients receiving chemotherapy alone. CCRT after ICT did not improve 1-year survival significantly in LAPC patients compared with chemotherapy alone (58% vs. 52%). ICT lasted for at least 3 months revealed significantly improved survival of additional CCRT to LAPC patients compared to chemotherapy alone (65% vs. 52%). A marginal survival benefit of consolidation CCRT was noted in studies using maintenance chemotherapy (59% vs. 52%), and fluorouracil-based CCRT (64% vs. 52%), as well as in studies conducted after the 2010 (64% vs. 55%).

Conclusion

The survival benefit of ICT+CCRT over chemotherapy alone in treating LAPC was noted when ICT lasted for at least 3 months. Fluorouracil-based CCRT, and maintenance chemotherapy were associated with improved clinical outcomes.

Never let it go: Stopping key mechanisms underlying metastasis to fight pancreatic cancer

Pancreatic ductal adenocarcinoma (PDAC) is an extremely aggressive neoplasm, predicted to become the second leading cause of cancer-related deaths before 2030. This dismal trend is mainly due to lack of effective treatments against its metastatic behavior. Therefore, a better understanding of the key mechanisms underlying metastasis should provide new opportunities for therapeutic purposes. Genomic analyses revealed that aberrations that fuel PDAC tumorigenesis and progression, such as SMAD4 loss, are also implicated in metastasis. Recently, microRNAs have been shown to play a regulatory role in the metastatic behavior of many tumors, including PDAC. In particular, miR-10 and miR-21 have appeared as master regulators of the metastatic program, while members of the miR-200 family are involved in the epithelial-to-mesenchymal switch, favoring cell migration and invasiveness. Several studies have also found a close relationship between cancer stem cells (CSCs) and biological features of metastasis, and the CSC markers ALDH1, ABCG2 and c-Met are expressed at high levels in metastatic PDAC cells. Emerging evidence reveals that exosomes are involved in the modulation of the tumor microenvironment and can initiate PDAC pre-metastatic niche formation in the liver and lungs. In this review, we provide an overview of the role of all these pivotal factors in the metastatic behavior of PDAC, and discuss their potential exploitation in the clinic to improve current therapeutics and identify new drug targets.

Recurrent noncoding regulatory mutations in pancreatic ductal adenocarcinoma

The contributions of coding mutations to tumorigenesis are relatively well known; however, little is known about somatic alterations in noncoding DNA. Here we describe GECCO (Genomic Enrichment Computational Clustering Operation) to analyze somatic noncoding alterations in 308 pancreatic ductal adenocarcinomas (PDAs) and identify commonly mutated regulatory regions. We find recurrent noncoding mutations to be enriched in PDA pathways, including axon guidance and cell adhesion, and newly identified processes, including transcription and homeobox genes. We identified mutations in protein binding sites correlating with differential expression of proximal genes and experimentally validated effects of mutations on expression. We developed an expression modulation score that quantifies the strength of gene regulation imposed by each class of regulatory elements, and found the strongest elements were most frequently mutated, suggesting a selective advantage. Our detailed single-cancer analysis of noncoding alterations identifies regulatory mutations as candidates for diagnostic and prognostic markers, and suggests new mechanisms for tumor evolution.

The Impact of SMAD4 Loss on Outcome in Patients with Advanced Pancreatic Cancer Treated with Systemic Chemotherapy

The role of the tumor suppressor mothers against decapentaplegic homolog 4 (SMAD4) has not yet been defined in patients (pts) with advanced pancreatic cancer (aPC). This translational research study was designed to evaluate the impact of tumoral SMAD4 loss on clinicopathological parameters and outcome in PC patients receiving palliative chemotherapy. Using immunohistochemistry, we examined SMAD4 expression in tumor tissue of 143 aPC pts treated within completed prospective clinical and biomarker trials. In uni- and multivariate analyses, SMAD4 expression status was correlated to clinicopathological patient characteristics and outcome. At chemotherapy initiation, 128 pts had metastatic PC; most pts (n = 99) received a gemcitabine-based regimen. SMAD4 loss was detected in 92 pts (64%); patient characteristics such as gender, age, tumor grading, disease stage or number of metastatic sites had no significant impact on tumoral SMAD4 status. In univariate analyses, SMAD4 loss had no impact on overall survival (hazard ratio (HR) 1.008, p = 0.656); however, we observed a prolonged progression-free survival (HR 1.565, p = 0.038) in pts with tumoral SMAD4 loss. This finding was confirmed in multivariate analyses (HR 1.790, p = 0.040), but only for gemcitabine-treated pts. In contrast to previous studies in resectable PC, loss of SMAD4 expression was not associated with a negative outcome in patients with advanced PC receiving systemic chemotherapy.

Molecular Events in the Natural History of Pancreatic Cancer

Pancreatic ductal adenocarcinoma (PDAC) is among the deadliest epithelial malignancies. Improvements in our understanding of PDAC carcinogenesis will hopefully improve its detection, management, and outcomes, as has been achieved with other malignancies. Here we review the literature on the natural history of PDAC, including its cell of origin, the initiating somatic mutational events, pathways deranged in the mature tumor, its biological heterogeneity, and the relationship of the primary tumor with metastases. We also suggest areas for further research and highlight translatable findings that are beginning to make clinical inroads.

For robust big data analyses: a collection of 150 important pro-metastatic genes

Metastasis is the greatest contributor to cancer-related death. In the era of precision medicine, it is essential to predict and to prevent the spread of cancer cells to significantly improve patient survival. Thanks to the application of a variety of high-throughput technologies, accumulating big data enables researchers and clinicians to identify aggressive tumors as well as patients with a high risk of cancer metastasis. However, there have been few large-scale gene collection studies to enable metastasis-related analyses. In the last several years, emerging efforts have identified pro-metastatic genes in a variety of cancers, providing us the ability to generate a pro-metastatic gene cluster for big data analyses. We carefully selected 285 genes with in vivo evidence of promoting metastasis reported in the literature. These genes have been investigated in different tumor types. We used two datasets downloaded from The Cancer Genome Atlas database, specifically, datasets of clear cell renal cell carcinoma and hepatocellular carcinoma, for validation tests, and excluded any genes for which elevated expression level correlated with longer overall survival in any of the datasets. Ultimately, 150 pro-metastatic genes remained in our analyses. We believe this collection of pro-metastatic genes will be helpful for big data analyses, and eventually will accelerate anti-metastasis research and clinical intervention.

Five-Year Actual Overall Survival in Resected Pancreatic Cancer: A Contemporary Single-Institution Experience from a Multidisciplinary Perspective

BACKGROUND

Successful surgical resection combined with effective perioperative therapy is essential for maximizing long-term survival for pancreatic adenocarcinoma.

PATIENTS AND METHODS

All patients with pancreatic adenocarcinoma who underwent curative resection at our institution from January 2003 to May 2010 were reviewed. Demographic and clinical details were retrospectively collected from medical records and cancer registry data.

RESULTS

Overall, 176 patients were included in the analysis (148 with de novo resectable disease and 28 with borderline resectable disease at presentation). Among 106 patients who received all perioperative therapy at our institution, 94% received neoadjuvant and/or adjuvant treatment in addition to resection. Actual all-cause 5-year overall survival (OS) for all 176 patients was 30.7%, with a median OS of 33.9 months [95% confidence interval (CI) 28.1-39.6 months]. For patients who received all perioperative therapy at our institution, actual all-cause 5-year disease-free survival (DFS) was 32.1%, with a median DFS of 28.8 months (95% CI 20.1-43.6 months). Of these patients, 67/106 (63%) recurred: 8 (8%) locoregional only; 52 (49%) systemic only; and 7 (7%) combined recurrence. No difference in survival rates or recurrence patterns was seen between resectable and borderline resectable patients. In multivariate analysis, tumor differentiation (poor vs. non-poor) and lymph node ratio >20% produced a useful clinical model.

CONCLUSION

The actual OS rates for resected pancreatic cancer shown in this study are reflective of those currently achievable at a tertiary medical center dedicated to this patient population. In considering these results, both frequency and type of adjuvant/neoadjuvant therapy administered in the context of the clinical experience/management techniques of providers administering these treatments will be discussed.

The Emerging Roles of RUNX Transcription Factors in Epithelial-Mesenchymal Transition

Epithelial-mesenchymal transition (EMT) is an evolutionary conserved morphogenetic program necessary for the shaping of the body plan during development. It is guided precisely by growth factor signaling and a dedicated network of specialised transcription factors. These are supported by other transcription factor families serving auxiliary functions during EMT, beyond their general roles as effectors of major signaling pathways. EMT transiently induces in epithelial cells mesenchymal properties, such as the loss of cell-cell adhesion and a gain in cell motility. Together, these newly acquired properties enable their migration to distant sites where they eventually give rise to adult epithelia. However, it is now recognized that EMT contributes to the pathogenesis of several human diseases, notably in tissue fibrosis and cancer metastasis. The RUNX family of transcription factors are important players in cell fate determination during development, where their spatio-temporal expression often overlaps with the occurrence of EMT. Furthermore, the dysregulation of RUNX expression and functions are increasingly linked to the aberrant induction of EMT in cancer. The present chapter reviews the current knowledge of this emerging field and the common themes of RUNX involvement during EMT, with the intention of fostering future research.

Runx3 and Cell Fate Decisions in Pancreas Cancer

The RUNX family transcription factors are critical regulators of development and frequently dysregulated in cancer. RUNX3, the least well characterized of the three family members, has been variously described as a tumor promoter or suppressor, sometimes with conflicting results and opinions in the same cancer and likely reflecting a complex role in oncogenesis. We recently identified RUNX3 expression as a crucial determinant of the predilection for pancreatic ductal adenocarcinoma (PDA) cells to proliferate locally or promulgate throughout the body. High RUNX3 expression induces the production and secretion of soluble factors that support metastatic niche construction and stimulates PDA cells to migrate and invade, while simultaneously suppressing proliferation through increased expression of cell cycle regulators such as CDKN1A/p21 ^WAF1/CIP1 . RUNX3 expression and function are coordinated by numerous transcriptional and post-translational inputs, and interactions with diverse cofactors influence whether the resulting RUNX3 complexes enact tumor suppressive or tumor promoting programs. Understanding these exquisitely context-dependent tumor cell behaviors has the potential to inform clinical decision-making including the most appropriate timing and sequencing of local vs. systemic therapies.

Runx3 in Immunity, Inflammation and Cancer

In this chapter we summarize the pros and cons of the notion that Runx3 is a major tumor suppressor gene (TSG). Inactivation of TSGs in normal cells provides a viability/growth advantage that contributes cell-autonomously to cancer. More than a decade ago it was suggested that RUNX3 is involved in gastric cancer development, a postulate extended later to other epithelial cancers portraying RUNX3 as a major TSG. However, evidence that Runx3 is not expressed in normal gastric and other epithelia has challenged the RUNX3-TSG paradigm. In contrast, RUNX3 is overexpressed in a significant fraction of tumor cells in various human epithelial cancers and its overexpression in pancreatic cancer cells promotes their migration, anchorage-independent growth and metastatic potential. Moreover, recent high-throughput quantitative genome-wide studies on thousands of human samples of various tumors and new investigations of the role of Runx3 in mouse cancer models have unequivocally demonstrated that RUNX3 is not a bona fide cell-autonomous TSG. Importantly, accumulating data demonstrated that RUNX3 functions in control of immunity and inflammation, thereby indirectly influencing epithelial tumor development.

The role of hypoxia in pancreatic cancer: a potential therapeutic target?

One of the key factors that correlates with poor survival of patients with pancreatic cancer is the extent of hypoxic areas within the tumor tissue. The adaptation of pancreatic cancer cells to limited oxygen delivery promotes the induction of an invasive and treatment-resistant phenotype, triggering metastases at an early stage of tumor development, which resist in most cases adjuvant therapies following tumor resection. In this article, the authors summarize the evidence demonstrating the significance of hypoxia in pancreatic cancer pathogenesis and discuss the possible hypoxia-induced mechanisms underlying its aggressive nature. We then conclude with promising strategies that target hypoxia-adapted pancreatic cancer cells.

Angiogenic gene signature in human pancreatic cancer correlates with TGF-beta and inflammatory transcriptomes

Pancreatic ductal adenocarcinomas (PDACs) are hypovascular, but overexpress pro-angiogenic factors and exhibit regions of microvasculature. Using RNA-seq data from The Cancer Genome Atlas (TCGA), we previously reported that ∼12% of PDACs have an angiogenesis gene signature with increased expression of multiple pro-angiogenic genes. By analyzing the recently expanded TCGA dataset, we now report that this signature is present in ∼35% of PDACs but that it is mostly distinct from an angiogenesis signature present in pancreatic neuroendocrine tumors (PNETs). These PDACs exhibit a transcriptome that reflects active TGF-β signaling, and up-regulation of several pro-inflammatory genes, and many members of JAK signaling pathways. Moreover, expression of SMAD4 and HDAC9 correlates with endothelial cell abundance in PDAC tissues. Concomitantly targeting the TGF-β type I receptor (TβRI) kinase with SB505124 and JAK1-2 with ruxolitinib suppresses JAK1 phosphorylation and blocks proliferative cross-talk between human pancreatic cancer cells (PCCs) and human endothelial cells (ECs), and these anti-proliferative effects were mimicked by JAK1 silencing in ECs. By contrast, either inhibitor alone does not suppress their enhanced proliferation in 3D co-cultures. These findings suggest that targeting both TGF-β and JAK1 signaling could be explored therapeutically in the 35% of PDAC patients whose cancers exhibit an angiogenesis gene signature.

Epithelial-to-mesenchymal transition confers pericyte properties on cancer cells

Carcinoma cells can acquire increased motility and invasiveness through epithelial-to-mesenchymal transition (EMT). However, the significance of EMT in cancer metastasis has been controversial, and the exact fates and functions of EMT cancer cells in vivo remain inadequately understood. Here, we tracked epithelial cancer cells that underwent inducible or spontaneous EMT in various tumor transplantation models. Unlike epithelial cells, the majority of EMT cancer cells were specifically located in the perivascular space and closely associated with blood vessels. EMT markedly activated multiple pericyte markers in carcinoma cells, in particular PDGFR-β and N-cadherin, which enabled EMT cells to be chemoattracted towards and physically interact with endothelium. In tumor xenografts generated from carcinoma cells that were prone to spontaneous EMT, a substantial fraction of the pericytes associated with tumor vasculature were derived from EMT cancer cells. Depletion of such EMT cells in transplanted tumors diminished pericyte coverage, impaired vascular integrity, and attenuated tumor growth. These findings suggest that EMT confers key pericyte attributes on cancer cells. The resulting EMT cells phenotypically and functionally resemble pericytes and are indispensable for vascular stabilization and sustained tumor growth. This study thus proposes a previously unrecognized role for EMT in cancer.

Mutant p53 Together with TGFβ Signaling Influence Organ-Specific Hematogenous Colonization Patterns of Pancreatic Cancer

Purpose: TP53 and the TGFβ pathway are major mediators of pancreatic cancer metastasis. The mechanisms by which they cause hematogenous metastasis have not been fully explored.Experimental Design:KPC (LSL-KRAS^G12D/+;LSL-Trp53^R172H/+; Ptf1a^Cre/+) mice were generated, and the frequency and morphology of organ-specific hematogenous metastases compared with that seen in KPTC and KTC littermates (Tgfbr2^+/-). Key findings were validated in primary cells from each genotype and samples of human pancreatic cancer liver metastases.Results: The frequency of hematogenous metastasis in KPTC mice was significantly lower than for KPC mice (41% vs. 68%, P < 0.05), largely due to a reduction in liver metastases. No differences were found between KPC and KPTC lung metastases, whereas liver metastases in KPTC mice showed a profound extravasation deficiency characterized by sinusoidal growth and lack of desmoplastic stroma. Analogous findings were confirmed in liver samples from patients indicating their clinical relevance. Portal vein colonization as a direct mode of access to the liver was observed in both mice and humans. Secretome analyses of KPC cells revealed an abundance of secreted prometastatic mediators including Col6A1 and Lcn2 that promoted early steps of metastatic colonization. These mediators were overexpressed in primary tumors but not metastases, suggesting that the ability to colonize is, in part, developed within the primary site, a phenomenon we refer to as the "Cinderella effect."Conclusions: These findings establish a novel paradigm for understanding pancreatic cancer metastasis and the observed clinical latencies of liver versus lung metastases specifically. Clin Cancer Res; 23(6); 1607-20. ©2016 AACR.

An in vivo multiplexed small-molecule screening platform

Phenotype-based small-molecule screening is a powerful method to identify molecules that regulate cellular functions. However, such screens are generally performed in vitro under conditions that do not necessarily model complex physiological conditions or disease states. Here, we use molecular cell barcoding to enable direct in vivo phenotypic screening of small-molecule libraries. The multiplexed nature of this approach allows rapid in vivo analysis of hundreds to thousands of compounds. Using this platform, we screened >700 covalent inhibitors directed toward hydrolases for their effect on pancreatic cancer metastatic seeding. We identified multiple hits and confirmed the relevant target of one compound as the lipase ABHD6. Pharmacological and genetic studies confirmed the role of this enzyme as a regulator of metastatic fitness. Our results highlight the applicability of this multiplexed screening platform for investigating complex processes in vivo.

Pancreatic cancer biology and genetics from an evolutionary perspective

Cancer is an evolutionary disease, containing the hallmarks of an asexually reproducing unicellular organism subject to evolutionary paradigms. Pancreatic ductal adenocarcinoma (hereafter referred to as pancreatic cancer) is a particularly robust example of this phenomenon. Genomic features indicate that pancreatic cancer cells are selected for fitness advantages when encountering the geographic and resource-depleted constraints of the microenvironment. Phenotypic adaptations to these pressures help disseminated cells to survive in secondary sites, a major clinical problem for patients with this disease. In this Review we gather the wide-ranging aspects of pancreatic cancer research into a single concept rooted in Darwinian evolution, with the goal of identifying novel insights and opportunities for study.

Neo-cartilage engineered from primary chondrocytes is epigenetically similar to autologous cartilage, in contrast to using mesenchymal stem cells

OBJECTIVES

To compare the epigenetic landscape of 3D cell models of human primary articular chondrocytes (hPACs) and human bone-marrow derived mesenchymal stem cells (hBMSCs) and their respective autologous articular cartilage.

DESIGN

Using Illumina Infinium HumanMethylation450 BeadChip arrays, the DNA methylation landscape of the different cell sources and autologous cartilage was determined. Pathway enrichment was analyzed using DAVID.

RESULTS

Principal Component Analysis (PCA) of methylation data revealed separate clustering of hBMSC samples. Between hBMSCs and autologous cartilage 86,881 cytosine-phosphate-guanine dinucleotides (CpGs) (20.2%), comprising 3,034 differentially methylated regions (DMRs; Δβ > 0.1; with the same direction of effect), were significantly differentially methylated. In contrast, between hPACs and autologous cartilage only 5,706 CpGs (1.33%) were differentially methylated. Of interest was the finding of the transcriptionally active, hyper-methylation of a Cartilage Intermediate Layer Protein (CILP) annotated DMR (Δβ = 0.16) in PAC-cartilage, corresponding to a profound decrease in CILP expression after in vitro culturing of hPACs as compared to autologous cartilage.

CONCLUSIONS

In vitro engineered neo-cartilage tissue from primary chondrocytes, hPACs, exhibits a DNA methylation landscape that is almost identical (99% similarity) to autologous cartilage, in contrast to neo-cartilage engineered from bone marrow-derived mesenchymal stem cells (MSCs). Although hBMSCs are widely used for cartilage engineering purposes the effects of these vast differences on cartilage regeneration and long term consequences of implantation, are not known. The use of hBMSCs or hPACs for future cartilage tissue regeneration purposes should therefore be investigated in more depth in future endeavors to better understand the consequences of the differential methylome on neo-cartilage.