Nr5a2 heterozygosity sensitises to, and cooperates with, inflammation in KRas(G12V)-driven pancreatic tumourigenesis

Exploring the distribution of polymorphism across diverse breeds Worldwide in the bovine NR5A2 gene and its correlation with number of mature follicles and corpus albicans

The Nuclear receptor subfamily 5 group A member 2 (NR5A2) gene plays a pivotal role in ovarian development, ovulation, and reproductive traits. There is a lack of studies on its impact on ovarian traits and reproductive traits in cattle. This study aimed to explore NR5A2 gene polymorphisms associations with reproductive traits and investigate the distribution of NR5A2 gene polymorphisms across diverse bovine breeds worldwide. We identified a novel 17-bp deletion within the NR5A2 gene specifically in Chinese Holstein cows (n = 1033) leading to the observation of two genotypes DD and ID. Subsequent association analysis revealed a significant correlation between the 'ID' genotype at this locus and a larger number of corpus albicans (p = 0.042) in diestrus, as well as a higher number of mature follicles (p = 0.038) in estrus. In addition, we also found that the distribution of this deletion exhibits strong regionality across different cattle breeds globally. These findings indicate that the 17-bp deletion mutation within the NR5A2 gene is significantly associated with an increased corpus luteum diameter and a greater number of mature follicles, suggesting its potential utility as a valuable DNA marker for enhancing cow fertility.

A common CTRB misfolding variant associated with pancreatic cancer risk causes ER stress and inflammation in mice

Objective

Genome wide association studies have identified an exon 6 CTRB2 deletion variant that associates with increased risk of pancreatic cancer. To acquire evidence on its causal role, we developed a new mouse strain carrying an equivalent variant in Ctrb1 , the mouse orthologue of CTRB2 .

Design

We used CRISPR/Cas9 to introduce a 707bp deletion in Ctrb1 encompassing exon 6 ( Ctrb1 Δexon6 ). This mutation closely mimics the human deletion variant. Mice carrying the mutant allele were extensively profiled at 3 months to assess their phenotype.

Results

Ctrb1 Δexon6 mutant mice express a truncated CTRB1 that accumulates in the ER. The pancreas of homozygous mutant mice displays reduced chymotrypsin activity and total protein synthesis. The histological aspect of the pancreas is inconspicuous but ultrastructural analysis shows evidence of dramatic ER stress and cytoplasmic and nuclear inclusions. Transcriptomic analyses of the pancreas of mutant mice reveals acinar program down-regulation and increased activity of ER stress-related and inflammatory pathways. Heterozygous mice have an intermediate phenotype. Agr2 is one of the most up-regulated genes in mutant pancreata. Ctrb1 Δexon6 mice exhibit impaired recovery from acute caerulein-induced pancreatitis. Administration of TUDCA or sulindac partially alleviates the phenotype. A transcriptomic signature derived from the mutant pancreata is significantly enriched in normal human pancreas of CTRB2 exon 6 deletion variant carriers from the GTEx cohort.

Conclusions

This mouse strain provides formal evidence that the Ctrb1 Δexon6 variant causes ER stress and inflammation in vivo , providing an excellent model to understand its contribution to pancreatic ductal adenocarcinoma development and to identify preventive strategies.

SUMMARY BOX

What is already known about this subject?: - CTRB2 is one of the most abundant proteins produced by human pancreatic acinar cells. - A common exon 6 deletion variant in CTRB2 has been associated with an increased risk of pancreatic ductal adenocarcinoma. - Misfolding of digestive enzymes is associated with pancreatic pathology.What are the new findings?: - We developed a novel genetic model that recapitulates the human CTRB2 deletion variant in the mouse orthologue, Ctrb1 . - Truncated CTRB1 misfolds and accumulates in the ER; yet, mutant mice display a histologically normal pancreas at 3 months age.- CTRB1 and associated chaperones colocalize in the ER, the cytoplasm, and the nucleus of acinar cells.- Transcriptomics analysis reveals reduced activity of the acinar program and increased activity of pathways involved in ER stress, unfolded protein response, and inflammation.- Mutant mice are sensitized to pancreatic damage and do not recover properly from a mild caerulein-induced pancreatitis.- TUDCA administration partially relieves the ER stress in mutant mice.How might it impact on clinical practice in the foreseeable future?: - The new mouse model provides a tool to identify the mechanisms leading to increased pancreatic cancer risk in CTRB2 exon 6 carriers. - The findings suggest that drugs that cause ER stress relief and/or reduce inflammation might provide preventive opportunities.

Diagnostic and Prognostic Markers for Pancreatitis and Pancreatic Ductal Adenocarcinoma

Diagnostic markers are desperately needed for the early detection of pancreatic ductal adenocarcinoma (PDA). We describe sets of markers expressed in temporal order in mouse models during pancreatitis, PDA initiation and progression. Cell type specificity and the differential expression of PDA markers were identified by screening single cell (sc) RNAseq from tumor samples of a mouse model for PDA (KIC) at early and late stages of PDA progression compared to that of a normal pancreas. Candidate genes were identified from three sources: (1) an unsupervised screening of the genes preferentially expressed in mouse PDA tumors; (2) signaling pathways that drive PDA, including the Ras pathway, calcium signaling, and known cancer genes, or genes encoding proteins that were identified by differential mass spectrometry (MS) of mouse tumors and conditioned media from human cancer cell lines; and (3) genes whose expression is associated with poor or better prognoses (PAAD, oncolnc.org). The developmental progression of PDA was detected in the temporal order of gene expression in the cancer cells of the KIC mice. The earliest diagnostic markers were expressed in epithelial cancer cells in early-stage, but not late-stage, PDA tumors. Other early markers were expressed in the epithelium of both early- and late-state PDA tumors. Markers that were expressed somewhat later were first elevated in the epithelial cancer cells of the late-stage tumors, then in both epithelial and mesenchymal cells, or only in mesenchymal cells. Stromal markers were differentially expressed in early- and/or late-stage PDA neoplasia in fibroblast and hematopoietic cells (lymphocytes and/or macrophages) or broadly expressed in cancer and many stromal cell types. Pancreatitis is a risk factor for PDA in humans. Mouse models of pancreatitis, including caerulein treatment and the acinar-specific homozygous deletion of differentiation transcription factors (dTFs), were screened for the early expression of all PDA markers identified in the KIC neoplasia. Prognostic markers associated with a more rapid decline were identified and showed differential and cell-type-specific expression in PDA, predominately in late-stage epithelial and/or mesenchymal cancer cells. Select markers were validated by immunohistochemistry in mouse and human samples of a normal pancreas and those with early- and late-stage PDA. In total, we present 2165 individual diagnostic and prognostic markers for disease progression to be tested in humans from pancreatitis to late-stage PDA.

NR5A2 gene affects the overall survival of LUAD patients by regulating the activity of CSCs through SNP pathway by OCLR algorithm and immune score

Objective

Differentially expressed genes (DEGs) in lung adenocarcinoma (LUAD) tumor stem cells were screened, and the biological characteristics of NR5A2 gene were investigated.

Methods

The expression and prognosis of NR5A2 in human LUAD were predicted and analyzed through bioinformatics analysis from a human cancer database. Gene expression and clinical data of LUAD tumor and normal lung tissues were obtained from The Cancer Genome Atlas (TCGA) database, and DEGs associated with lung cancer tumor stem cells (CSCs) were screened. Univariate and multivariate Cox regression models were used to screen and establish prognostic risk prediction models. The immune function of the patients was scored according to the model, and the relative immune functions of the high- and low-risk groups were compared to determine the difference in survival prognosis between the two groups. In addition, we calculated the index of stemness based on the transcriptome of the samples using one-class linear regression (OCLR).

Results

Bioinformatics analysis of a clinical cancer database showed that NR5A2 was significantly decreased in human LUAD tissues than in normal lung tissues, and the decrease in NR5A2 gene expression shortened the overall survival and progression-free survival of patients with LUAD.

Conclusion

The NR5A2 gene may regulate LUAD tumor stem cells through selective splicing mutations, thereby affecting the survival and prognosis of patients with lung cancer, and the NR5A2 gene may regulate CSCs through single nucleotide polymorphism.

NR5A2 promotes malignancy progression and mediates the effect of cisplatin in cutaneous squamous cell carcinoma

INTRODUCTION

Nuclear receptor subfamily five group A member two (NR5A2) plays a key role in the development of many tumor types, while it is uncertain in cutaneous squamous cell carcinoma (cSCC). The aim of this work was to determine the role of NR5A2 in cSCC proliferation, and to determine whether NR5A2 mediates the effect of cisplatin in cSCC.

METHODS

We performed a systematic study of existing data and conducted a preliminary bioinformatics analysis of NR5A2 expression in cSCC using bioinformatics databases. Immunohistochemical staining was performed on cSCC tissues of seven patients to study NR5A2 expression. NR5A2 expression was examined in human keratin-forming cells (HaCaT) and human cSCC cells (A431, Colo-16, SCL-1, SCL-2, and HSC-5). Stable A431 and SCL-2 cell lines consisting of sh-RNA-NR5A2 were constructed to detect changes in cell proliferation, cell cycle, apoptosis, and to determine the key proteins in the Wnt/β-catenin pathway. We also investigated changes in the effects of cisplatin on cSCC cells by CCK-8, clone formation assay, and Flow apoptosis assay after NR5A2 knockdown.

RESULTS

NR5A2 showed enhanced expression in cSCC tissues than in healthy tissues. Downregulation of NR5A2 in cSCC cells led to the formation of a less malignant phenotype. In contrast, the proliferative capacity of the cSCC cells was enhanced posttreatment with RJW100, an NR5A2 agonist. Additionally, NR5A2 knockdown led to a decrease in the expression level of the proteins in the Wnt/β-catenin pathway, and this inhibition was reversed by LiCl and recombinant antibody, Wnt3a. Moreover, NR5A2 knockdown resulted in diminished proliferative capacity and increased apoptotic cells after the addition of cisplatin.

CONCLUSION

NR5A2 plays a crucial role in the progression of cSCC, and the Wnt/β-catenin signaling pathway may be involved in the regulation of NR5A2-mediated cSCC. Knockdown of NR5A2 enhanced both the proliferation inhibiting and apoptosis promoting effects of cisplatin on cSCC.

Key transcriptional effectors of the pancreatic acinar phenotype and oncogenic transformation

Proper maintenance of mature cellular phenotypes is essential for stable physiology, suppression of disease states, and resistance to oncogenic transformation. We describe the transcriptional regulatory roles of four key DNA-binding transcription factors (Ptf1a, Nr5a2, Foxa2 and Gata4) that sit at the top of a regulatory hierarchy controlling all aspects of a highly differentiated cell-type-the mature pancreatic acinar cell (PAC). Selective inactivation of Ptf1a, Nr5a2, Foxa2 and Gata4 individually in mouse adult PACs rapidly altered the transcriptome and differentiation status of PACs. The changes most emphatically included transcription of the genes for the secretory digestive enzymes (which conscript more than 90% of acinar cell protein synthesis), a potent anabolic metabolism that provides the energy and materials for protein synthesis, suppressed and properly balanced cellular replication, and susceptibility to transformation by oncogenic KrasG12D. The simultaneous inactivation of Foxa2 and Gata4 caused a greater-than-additive disruption of gene expression and uncovered their collaboration to maintain Ptf1a expression and control PAC replication. A measure of PAC dedifferentiation ranked the effects of the conditional knockouts as Foxa2+Gata4 > Ptf1a > Nr5a2 > Foxa2 > Gata4. Whereas the loss of Ptf1a or Nr5a2 greatly accelerated Kras-mediated transformation of mature acinar cells in vivo, the absence of Foxa2, Gata4, or Foxa2+Gata4 together blocked transformation completely, despite extensive dedifferentiation. A lack of correlation between PAC dedifferentiation and sensitivity to oncogenic KrasG12D negates the simple proposition that the level of differentiation determines acinar cell resistance to transformation.

NFIC regulates ribosomal biology and ER stress in pancreatic acinar cells and restrains PDAC initiation

Pancreatic acinar cells rely on PTF1 and other transcription factors to deploy their transcriptional program. We identify NFIC as a NR5A2 interactor and regulator of acinar differentiation. NFIC binding sites are enriched in NR5A2 ChIP-Sequencing peaks. Nfic knockout mice have a smaller, histologically normal, pancreas with reduced acinar gene expression. NFIC binds and regulates the promoters of acinar genes and those involved in RNA/protein metabolism, and Nfic knockout pancreata show defective ribosomal RNA maturation. NFIC dampens the endoplasmic reticulum stress program through binding to gene promoters and is required for resolution of Tunicamycin-mediated stress. NFIC is down-regulated during caerulein pancreatitis and is required for recovery after damage. Normal human pancreata with low levels of NFIC transcripts display reduced expression of genes down-regulated in Nfic knockout mice. NFIC expression is down-regulated in mouse and human pancreatic ductal adenocarcinoma. Consistently, Nfic knockout mice develop a higher number of mutant Kras-driven pre-neoplastic lesions.

p53 inhibitor iASPP is an unexpected suppressor of KRAS and inflammation-driven pancreatic cancer

Oncogenic KRAS activation, inflammation and p53 mutation are key drivers of pancreatic cancer (PC) development. Here we report iASPP, an inhibitor of p53, as a paradoxical suppressor of inflammation and oncogenic KRAS^G12D-driven PC tumorigenesis. iASPP suppresses PC onset driven by KRAS^G12D alone or KRAS^G12D in combination with mutant p53^R172H. iASPP deletion limits acinar-to-ductal metaplasia (ADM) in vitro but accelerates inflammation and KRAS^G12D-induced ADM, pancreatitis and PC tumorigenesis in vivo. KRAS^G12D/iASPP^Δ8/Δ8 tumours are well-differentiated classical PCs and their derivative cell lines form subcutaneous tumours in syngeneic and nude mice. Transcriptomically, either iASPP deletion or p53 mutation in the KRAS^G12D background altered the expression of an extensively overlapping gene set, comprised primarily of NF-κB and AP1-regulated inflammatory genes. All these identify iASPP as a suppressor of inflammation and a p53-independent oncosuppressor of PC tumorigenesis.

Pancreatic cancer: Advances and challenges

Pancreatic ductal adenocarcinoma (PDAC) remains one of the deadliest cancers. Significant efforts have largely defined major genetic factors driving PDAC pathogenesis and progression. Pancreatic tumors are characterized by a complex microenvironment that orchestrates metabolic alterations and supports a milieu of interactions among various cell types within this niche. In this review, we highlight the foundational studies that have driven our understanding of these processes. We further discuss the recent technological advances that continue to expand our understanding of PDAC complexity. We posit that the clinical translation of these research endeavors will enhance the currently dismal survival rate of this recalcitrant disease.

Clinical and Molecular Attributes and Evaluation of Pancreatic Cystic Neoplasm

Intraductal papillary mucinous neoplasms (IPMNs) and mucinous cystic neoplasms (MCNs) are all considered "Pancreatic cystic neoplasms (PCNs)" and show a varying risk of developing into pancreatic ductal adenocarcinoma (PDAC). These lesions display different molecular characteristics, mutations, and clinical manifestations. A lack of detailed understanding of PCN subtype characteristics and their molecular mechanisms limits the development of efficient diagnostic tools and therapeutic strategies for these lesions. Proper in vivo mouse models that mimic human PCNs are also needed to study the molecular mechanisms and for therapeutic testing. A comprehensive understanding of the current status of PCN biology, mechanisms, current diagnostic methods, and therapies will help in the early detection and proper management of patients with these lesions and PDAC. This review aims to describe all these aspects of PCNs, specifically IPMNs, by describing the future perspectives.

Docking Protein p130Cas Regulates Acinar to Ductal Metaplasia During Pancreatic Adenocarcinoma Development and Pancreatitis

BACKGROUND & AIMS

Acinar to ductal metaplasia is the prerequisite for the initiation of Kras-driven pancreatic ductal adenocarcinoma (PDAC), and candidate genes regulating this process are emerging from genome-wide association studies. The adaptor protein p130Cas emerged as a potential PDAC susceptibility gene and a Kras-synthetic lethal interactor in pancreatic cell lines; however, its role in PDAC development has remained largely unknown.

METHODS

Human PDAC samples and murine KrasG12D-dependent pancreatic cancer models of increasing aggressiveness were used. p130Cas was conditionally ablated in pancreatic cancer models to investigate its role during Kras-induced tumorigenesis.

RESULTS

We found that high expression of p130Cas is frequently detected in PDAC and correlates with higher histologic grade and poor prognosis. In a model of Kras-driven PDAC, loss of p130Cas inhibits tumor development and potently extends median survival. Deletion of p130Cas suppresses acinar-derived tumorigenesis and progression by means of repressing PI3K-AKT signaling, even in the presence of a worsening condition like pancreatitis.

CONCLUSIONS

Our observations finally demonstrated that p130Cas acts downstream of Kras to boost the PI3K activity required for acinar to ductal metaplasia and subsequent tumor initiation. This demonstrates an unexpected driving role of p130Cas downstream of Kras through PI3K/AKT, thus indicating a rational therapeutic strategy of targeting the PI3K pathway in tumors with high expression of p130Cas.

Molecular signaling in pancreatic ductal metaplasia: emerging biomarkers for detection and intervention of early pancreatic cancer

Pancreatic ductal metaplasia (PDM) is the transformation of potentially various types of cells in the pancreas into ductal or ductal-like cells, which eventually replace the existing differentiated somatic cell type(s). PDM is usually triggered by and manifests its ability to adapt to environmental stimuli and genetic insults. The development of PDM to atypical hyperplasia or dysplasia is an important risk factor for pancreatic intraepithelial neoplasia (PanIN) and pancreatic ductal adenocarcinoma (PDA). Recent studies using genetically engineered mouse models, cell lineage tracing, single-cell sequencing and others have unraveled novel cellular and molecular insights in PDM formation and evolution. Those novel findings help better understand the cellular origins and functional significance of PDM and its regulation at cellular and molecular levels. Given that PDM represents the earliest pathological changes in PDA initiation and development, translational studies are beginning to define PDM-associated cell and molecular biomarkers that can be used to screen and detect early PDA and to enable its effective intervention, thereby truly and significantly reducing the dreadful mortality rate of PDA. This review will describe recent advances in the understanding of PDM biology with a focus on its underlying cellular and molecular mechanisms, and in biomarker discovery with clinical implications for the management of pancreatic regeneration and tumorigenesis.

Deregulation of Transcription Factor Networks Driving Cell Plasticity and Metastasis in Pancreatic Cancer

Pancreatic cancer is a very aggressive disease with 5-year survival rates of less than 10%. The constantly increasing incidence and stagnant patient outcomes despite changes in treatment regimens emphasize the requirement of a better understanding of the disease mechanisms. Challenges in treating pancreatic cancer include diagnosis at already progressed disease states due to the lack of early detection methods, rapid acquisition of therapy resistance, and high metastatic competence. Pancreatic ductal adenocarcinoma, the most prevalent type of pancreatic cancer, frequently shows dominant-active mutations in KRAS and TP53 as well as inactivation of genes involved in differentiation and cell-cycle regulation (e.g. SMAD4 and CDKN2A). Besides somatic mutations, deregulated transcription factor activities strongly contribute to disease progression. Specifically, transcriptional regulatory networks essential for proper lineage specification and differentiation during pancreas development are reactivated or become deregulated in the context of cancer and exacerbate progression towards an aggressive phenotype. This review summarizes the recent literature on transcription factor networks and epigenetic gene regulation that play a crucial role during tumorigenesis.

Nuclear receptor subfamily 5 group A member 2 (NR5A2): role in health and diseases

Nuclear receptors are the regulatory molecules that mediate cellular signals as they interact with specific DNA sequences. NR5A2 is a member of NR5A subfamily having four members (Nr5a1-Nr5a4). NR5A2 shows involvement in diverse biological processes like reverse cholesterol transport, embryonic stem cell pluripotency, steroidogenesis, development and differentiation of embryo, and adult homeostasis. NR5A2 haploinsufficiency has been seen associated with chronic pancreatitis, pancreatic and gastrointestinal cancer. There is a close relationship between the progression of pancreatic cancer from chronic pancreatitis, NR5A2 serving a common link. NR5A2 activity is regulated by intracellular phospholipids, transcriptional coregulators and post-translational modifications. The specific ligand of NR5A2 is unknown hence called an orphan receptor, but specific phospholipids such as dilauroyl phosphatidylcholine and diundecanoyl phosphatidylcholine act as a ligand and they are established drug targets in various diseases. This review will focus on the NR5A2 structure, regulation of its activity, and role in biological processes and diseases. In future, need more emphasis on discovering small molecule agonists and antagonist, which act as a drug target for therapeutic applications.

Nuclear receptor NR5A2 negatively regulates cell proliferation and tumor growth in nervous system malignancies

Nervous system malignancies are characterized by rapid progression and poor survival rates. These clinical observations underscore the need for novel therapeutic insights and pharmacological targets. To this end, here, we identify the orphan nuclear receptor NR5A2/LRH1 as a negative regulator of cancer cell proliferation and promising pharmacological target for nervous system-related tumors. In particular, clinical data from publicly available databases suggest that high expression levels of NR5A2 are associated with favorable prognosis in patients with glioblastoma and neuroblastoma tumors. Consistently, we experimentally show that NR5A2 is sufficient to strongly suppress proliferation of both human and mouse glioblastoma and neuroblastoma cells without inducing apoptosis. Moreover, short hairpin RNA-mediated knockdown of the basal expression levels of NR5A2 in glioblastoma cells promotes their cell cycle progression. The antiproliferative effect of NR5A2 is mediated by the transcriptional induction of negative regulators of the cell cycle, CDKN1A (encoding for p21cip1), CDKN1B (encoding for p27kip1) and Prox1 Interestingly, two well-established agonists of NR5A2, dilauroyl phosphatidylcholine (DLPC) and diundecanoyl phosphatidylcholine, are able to mimic the antiproliferative action of NR5A2 in human glioblastoma cells via the induction of the same critical genes. Most importantly, treatment with DLPC inhibits glioblastoma tumor growth in vivo in heterotopic and orthotopic xenograft mouse models. These data indicate a tumor suppressor role of NR5A2 in the nervous system and render this nuclear receptor a potential pharmacological target for the treatment of nervous tissue-related tumors.

NR5A2 Is One of 12 Transcription Factors Predicting Prognosis in HNSCC and Regulates Cancer Cell Proliferation in a p53-Dependent Manner

Head and neck squamous cell carcinoma (HNSCC) rank seventh among the most common type of malignant tumor worldwide. Various evidences suggest that transcriptional factors (TFs) play a critical role in modulating cancer progression. However, the prognostic value of TFs in HNSCC remains unclear. Here, we identified a risk model based on a 12-TF signature to predict recurrence-free survival (RFS) in patients with HNSCC. We further analyzed the ability of the 12-TF to predict the disease-free survival time and overall survival time in HNSCC, and found that only NR5A2 down-regulation was strongly associated with shortened overall survival and disease-free survival time in HNSCC. Moreover, we systemically studied the role of NR5A2 in HNSCC and found that NR5A2 regulated HNSCC cell growth in a TP53 status-dependent manner. In p53 proficient cells, NR5A2 knockdown increased the expression of TP53 and activated the p53 pathway to enhance cancer cells proliferation. In contrast, NR5A2 silencing suppressed the growth of HNSCC cells with p53 loss/deletion by inhibiting the glycolysis process. Therefore, our results suggested that NR5A2 may serve as a promising therapeutic target in HNSCC harboring loss-of-function TP53 mutations.

Tumor cell heterogeneity and its transcriptional bases in pancreatic cancer: a tale of two cell types and their many variants

Pancreatic ductal adenocarcinoma (PDAC), one of the most highly lethal tumors, is characterized by complex histology, with a massive fibrotic stroma in which both pseudo-glandular structures and compact nests of abnormally differentiated tumor cells are embedded, in different proportions and with different mutual relationships in space. This complexity and the heterogeneity of the tumor component have hindered the development of a broadly accepted, clinically actionable classification of PDACs, either on a morphological or a molecular basis. Here, we discuss evidence suggesting that such heterogeneity can to a large extent, albeit not exclusively, be traced back to two main classes of PDAC cells that commonly coexist in the same tumor: cells that maintained their ability to differentiate toward endodermal, mucin-producing epithelia and epithelial cells unable to form glandular structures and instead characterized by various levels of squamous differentiation and the expression of mesenchymal lineage genes. The underlying gene regulatory networks and how they are controlled by distinct transcription factors, as well as the practical implications of these two different populations of tumor cells, are discussed.

NR5A2 transcriptional activation by BRD4 promotes pancreatic cancer progression by upregulating GDF15

NR5A2 is a transcription factor regulating the expression of various oncogenes. However, the role of NR5A2 and the specific regulatory mechanism of NR5A2 in pancreatic ductal adenocarcinoma (PDAC) are not thoroughly studied. In our study, Western blotting, real-time PCR, and immunohistochemistry were conducted to assess the expression levels of different molecules. Wound-healing, MTS, colony formation, and transwell assays were employed to evaluate the malignant potential of pancreatic cancer cells. We demonstrated that NR5A2 acted as a negative prognostic biomarker in PDAC. NR5A2 silencing inhibited the proliferation and migration abilities of pancreatic cancer cells in vitro and in vivo. While NR5A2 overexpression markedly promoted both events in vitro. We further identified that NR5A2 was transcriptionally upregulated by BRD4 in pancreatic cancer cells and this was confirmed by Chromatin immunoprecipitation (ChIP) and ChIP-qPCR. Besides, transcriptome RNA sequencing (RNA-Seq) was performed to explore the cancer-promoting effects of NR5A2, we found that GDF15 is a component of multiple down-regulated tumor-promoting gene sets after NR5A2 was silenced. Next, we showed that NR5A2 enhanced the malignancy of pancreatic cancer cells by inducing the transcription of GDF15. Collectively, our findings suggest that NR5A2 expression is induced by BRD4. In turn, NR5A2 activates the transcription of GDF15, promoting pancreatic cancer progression. Therefore, NR5A2 and GDF15 could be promising therapeutic targets in pancreatic cancer.

Molecular Alterations in Pancreatic Cancer: Transfer to the Clinic

Pancreatic ductal adenocarcinoma (PDA) is the most common cancer of the exocrine pancreas and probably the tumor that has benefited the least from clinical progress in the last three decades. A consensus has been reached regarding the histologic classification of the ductal preneoplastic lesions (pancreatic intra-epithelial neoplasia-PanIN) and the molecular alterations associated with them. Mutations in KRAS and inactivation of CDKN2A, SMAD4 and TP53 are among the most prevalent alterations. Next generation sequencing studies are providing a broad picture of the enormous heterogeneity in this tumor type, describing new mutations less prevalent. These studies have also allowed the characterization of different subtypes with prognostic value. However, all this knowledge has not been translated into a clinical progress. Effective preventive and early diagnostic strategies are essential to improve the survival rates. The main challenge is, indeed, to identify new effective drugs. Despite many years of research and its limited success, gemcitabine is still the first line treatment of PDA. New drug combinations and new concepts to improve drug delivery into the tumor, as well as the development of preclinical predictive assays, are being explored and provide optimism and prospects for better therapies.

More than acinar identity? A novel cystic phenotype suggests broader roles for NR5A2 in pancreatic cancer†

The prognosis for pancreatic ductal adenocarcinoma (PDAC) remains dismal. Multiple genome-wide association studies (GWAS) have implicated the nuclear receptor NR5A2 in modulating PDAC risk, but mechanisms for this association are not understood. NR5A2 is a transcription factor that maintains acinar cell identity, and heterozygous loss of Nr5a2 in mice accelerates oncogenic Kras-driven formation of pancreatic intraepithelial neoplasia (PanIN), a PDAC precursor derived from acinar cells. In a recent issue of The Journal of Pathology, Cobo et al characterize a novel mouse model that uses Ptf1a:Cre to drive oncogenic Kras as well as heterozygous Nr5a2 inactivation. In addition to the expected PanIN lesions, these mice exhibited a surprising phenotype: large pancreatic cystic lesions which have not been previously reported. Comparing expression of oncogenic Kras and heterozygous Nr5a2 in various mouse models reveals several possible explanations for these cystic lesions. Importantly, these differences across mouse models suggest that NR5A2 may contribute to PDAC precursors in ways beyond its previously characterized acinar cell-autonomous role. These observations highlight that pathways implicated by GWAS may have roles in unexpected cell types, and an understanding of these roles will be critical to guide new preventive and treatment strategies for PDAC. © 2021 The Pathological Society of Great Britain and Ireland. Published by John Wiley & Sons, Ltd.

Epithelial Nr5a2 heterozygosity cooperates with mutant Kras in the development of pancreatic cystic lesions

Cystic neoplasms of the pancreas are an increasingly important public health problem. The majority of these lesions are benign but some progress to invasive pancreatic ductal adenocarcinoma (PDAC). There is a dearth of mouse models of these conditions. The orphan nuclear receptor NR5A2 regulates development, differentiation, and inflammation. Germline Nr5a2 heterozygosity sensitizes mice to the oncogenic effects of mutant Kras in the pancreas. Here, we show that - unlike constitutive Nr5a2^+/- mice - conditional Nr5a2 heterozygosity in pancreatic epithelial cells, combined with mutant Kras (KPN^+/- ), leads to a dramatic replacement of the pancreatic parenchyma with cystic structures and an accelerated development of high-grade PanINs and PDAC. Timed histopathological analyses indicated that in KPN^+/- mice PanINs precede the formation of cystic lesions and the latter precede PDAC. A single episode of acute caerulein pancreatitis is sufficient to accelerate the development of cystic lesions in KPN^+/- mice. Epithelial cells of cystic lesions of KPN^+/- mice express MUC1, MUC5AC, and MUC6, but lack expression of MUC2, CDX2, and acinar markers, indicative of a pancreato-biliary/gastric phenotype. In accordance with this, in human samples we found a non-significantly decreased expression of NR5A2 in mucinous tumours, compared with conventional PDAC. These results highlight that the effects of loss of one Nr5a2 allele are time- and cell context-dependent. KPN^+/- mice represent a new model to study the formation of cystic pancreatic lesions and their relationship with PanINs and classical PDAC. Our findings suggest that pancreatitis could also contribute to acceleration of cystic tumour progression in patients. © 2020 The Pathological Society of Great Britain and Ireland. Published by John Wiley & Sons, Ltd.

Concerted cell and in vivo screen for pancreatic ductal adenocarcinoma (PDA) chemotherapeutics

PDA is a major cause of US cancer-related deaths. Oncogenic Kras presents in 90% of human PDAs. Kras mutations occur early in pre-neoplastic lesions but are insufficient to cause PDA. Other contributing factors early in disease progression include chronic pancreatitis, alterations in epigenetic regulators, and tumor suppressor gene mutation. GPCRs activate heterotrimeric G-proteins that stimulate intracellular calcium and oncogenic Kras signaling, thereby promoting pancreatitis and progression to PDA. By contrast, Rgs proteins inhibit Gi/q-coupled GPCRs to negatively regulate PDA progression. Rgs16::GFP is expressed in response to caerulein-induced acinar cell dedifferentiation, early neoplasia, and throughout PDA progression. In genetically engineered mouse models of PDA, Rgs16::GFP is useful for pre-clinical rapid in vivo validation of novel chemotherapeutics targeting early lesions in patients following successful resection or at high risk for progressing to PDA. Cultured primary PDA cells express Rgs16::GFP in response to cytotoxic drugs. A histone deacetylase inhibitor, TSA, stimulated Rgs16::GFP expression in PDA primary cells, potentiated gemcitabine and JQ1 cytotoxicity in cell culture, and Gem + TSA + JQ1 inhibited tumor initiation and progression in vivo. Here we establish the use of Rgs16::GFP expression for testing drug combinations in cell culture and validation of best candidates in our rapid in vivo screen.

Validation of genome-wide association study-identified single nucleotide polymorphisms in a case-control study of pancreatic cancer from Taiwan

Background

Due to differences in genetic background, it is unclear whether the genetic loci identified by the previous genome-wide association studies (GWAS) of pancreatic cancer also play significant roles in the development of pancreatic cancer among the Taiwanese population.

Methods

This study aimed to validate the 25 pancreatic cancer GWAS-identified single nucleotide polymorphisms (SNPs) in a case-control study (278 cases and 658 controls) of pancreatic cancer conducted in Taiwan. Statistical analyses were conducted to determine the associations between the GWAS-identified SNPs and pancreatic cancer risk. Gene-environment interaction analysis was conducted to evaluate the interactions between SNPs and environmental factors on pancreatic cancer risk.

Results

Among the 25 GWAS-identified SNPs, 7 (rs2816938 (~ 11 kb upstream of NR5A2), rs10094872 (~ 28 kb upstream of MYC), rs9581943 (200 bp upstream of PDX1) and 4 chromosome 13q22.1 SNPs: rs4885093, rs9573163, rs9543325, rs9573166) showed a statistically significant association with pancreatic cancer risk in the current study. Additional analyses showed two significant gene-environment interactions (between poor oral hygiene and NR5A2 rs2816938 and between obesity and PDX1 rs9581943) on the risk of pancreatic cancer.

Conclusions

The current study confirmed the associations between 7 of the 25 GWAS-identified SNPs and pancreatic risk among the Taiwanese population.

Furthermore, pancreatic cancer was jointly influenced by lifestyle and medical factors, genetic polymorphisms, and gene-environment interaction. Additional GWAS is needed to determine the genetic polymorphisms that are more relevant to the pancreatic cancer cases occurring in Taiwan.

Loss of Setd2 promotes Kras-induced acinar-to-ductal metaplasia and epithelia-mesenchymal transition during pancreatic carcinogenesis

OBJECTIVE

SETD2, the sole histone H3K36 trimethyltransferase, is frequently mutated or deleted in human cancer, including pancreatic ductal adenocarcinoma (PDAC). However, whether SETD2/H3K36me3 alteration results in PDAC remains largely unknown.

DESIGN

TCGA(PAAD) public database and PDAC tissue array with SETD2/H3K36me3 staining were used to investigate the clinical relevance of SETD2 in PDAC. Furthermore, to define the role of SETD2 in the carcinogenesis of PDAC, we crossed conditional Setd2 knockout mice (Pdx^creSetd2^flox/flox) together with Kras^G12D mice. Moreover, to examine the role of SETD2 after ductal metaplasia, Crisp/cas9 was used to deplete Setd2 in PDAC cells. RNA-seq and H3K36me3 ChIP-seq were performed to uncover the mechanism.

RESULTS

SETD2 mutant/low expression was correlated with poor prognosis in patients with PDAC. Next, we found that Setd2 acted as a putative tumour suppressor in Kras-driven pancreatic carcinogenesis. Mechanistically, Setd2 loss in acinar cells facilitated Kras-induced acinar-to-ductal reprogramming, mainly through epigenetic dysregulation of Fbxw7. Moreover, Setd2 ablation in pancreatic cancer cells enhanced epithelia-mesenchymal transition (EMT) through impaired epigenetic regulation of Ctnna1. In addition, Setd2 deficiency led to sustained Akt activation via inherent extracellular matrix (ECM) production, which would favour their metastasis.

CONCLUSION

Together, our findings highlight the function of SETD2 during pancreatic carcinogenesis, which would advance our understanding of epigenetic dysregulation in PDAC. Moreover, it may also pave the way for development of targeted, patients-tailored therapies for PDAC patients with SETD2 deficiency.

Men1 maintains exocrine pancreas homeostasis in response to inflammation and oncogenic stress

A more comprehensive understanding of the molecular mechanisms underlying pancreatic diseases, including pancreatitis and cancer, is essential to improve clinical management. MEN1 has established roles in epigenetic regulation and tumor suppression in the endocrine pancreas; however, intriguing recent data suggest MEN1 may also function in the exocrine pancreas. Using physiologically relevant genetic mouse models, we provide direct evidence that Men1 is essential for exocrine pancreas homeostasis in response to inflammation and oncogenic stress. Men1 loss causes increased injury and impaired regeneration following acute caerulein-induced pancreatitis, leading to more severe damage, loss of the normal acinar compartment, and increased cytokeratin 19-positive metaplasias and immune cell infiltration. We further demonstrate the Men1 protein is stabilized in response to insult, and loss of Men1 is associated with the overexpression of proinflammatory Jund target genes, suggesting that loss of Men1-mediated repression of Jund activity is, at least in part, responsible for the impaired response. Finally, we demonstrate that Men1 loss significantly accelerates mutant Kras-dependent oncogenesis. Combined, this work establishes Men1 as an important mediator of pancreas homeostasis in vivo.

Time for a paradigm shift in treating type 1 diabetes mellitus: coupling inflammation to islet regeneration

Type 1 diabetes mellitus (T1DM) is an autoimmune disease that targets the destruction of islet beta-cells resulting in insulin deficiency, hyperglycemia and death if untreated. Despite advances in medical devices and longer-acting insulin, there is still no robust therapy to substitute and protect beta-cells that are lost in T1DM. Attempts to refrain from the autoimmune attack have failed to achieve glycemic control in patients highlighting the necessity for a paradigm shift in T1DM treatment. Paradoxically, beta-cells are present in T1DM patients indicating a disturbed equilibrium between the immune attack and beta-cell regeneration reminiscent of unresolved wound healing that under normal circumstances progression towards an anti-inflammatory milieu promotes regeneration. Thus, the ultimate T1DM therapy should concomitantly restore immune self-tolerance and replenish the beta-cell mass similar to wound healing. Recently the agonistic activation of the nuclear receptor LRH-1/NR5A2 was shown to induce immune self-tolerance, increase beta-cell survival and promote regeneration through a mechanism of alpha-to-beta cell phenotypic switch. This trans-regeneration process appears to be facilitated by a pancreatic anti-inflammatory environment induced by LRH-1/NR5A2 activation. Herein, we review the literature on the role of LRH1/NR5A2 in immunity and islet physiology and propose that a cross-talk between these cellular compartments is mandatory to achieve therapeutic benefits.

Irreversible and sustained upregulation of endothelin axis during oncogene-associated pancreatic inflammation and cancer

Endothelin-1 (ET-1) and its two receptors, endothelin receptor A (ETAR) and endothelin receptor B (ETBR) exhibit deregulated overexprerssion in pancreatic ductal adenocarcinoma (PDAC) and pancreatitis. We examined the expression pattern of endothelin (ET) axis components in the murine models of chronic and acute inflammation in the presence or absence of oncogenic K-ras. While the expression of endothelin converting enzyme-1 (ECE-1), ET-1, ETAR and ETBR in the normal pancreas is restricted predominantly to the islet cells, progressive increase of ET receptors in ductal cells and stromal compartment is observed in the KC model (Pdx-1 Cre; K-rasG12D) of PDAC. In the murine pancreas harboring K-rasG12D mutation (KC mice), following acute inflammation induced by cerulein, increased ETAR and ETBR expression is observed in the amylase and CK19 double positive cells that represent cells undergoing pancreatic acinar to ductal metaplasia (ADM). As compared to the wild type (WT) mice, cerulein treatment in KC mice resulted in significantly higher levels of ECE-1, ET-1, ETAR and ETBR, transcripts in the pancreas. Similarly, in response to cigarette smoke-induced chronic inflammation, the expression of ET axis components is significantly upregulated in the pancreas of KC mice as compared to the WT mice. In addition to the expression in the precursor pancreatic intraepithelial neoplasm (PanIN lesions) in cigarette smoke-exposure model and metaplastic ducts in cerulein-treatment model, ETAR and ETBR expression is also observed in infiltrating F4/80 positive macrophages and α-SMA positive fibroblasts and high co-localization was seen in the presence of oncogenic K-ras. In conclusion, both chronic and acute pancreatic inflammation in the presence of oncogenic K-ras contribute to sustained upregulation of ET axis components in the ductal and stromal cells suggesting a potential role of ET axis in the initiation and progression of PDAC.

Lower Nr5a2 Level Downregulates the β-Catenin and TCF-4 Expression in Caerulein-Induced Pancreatic Inflammation

Nuclear receptor subfamily 5 group A member 2 (Nr5a2) is widely involved in the physiological and pathological processes of the pancreas. However, the cytological and molecular evidence regarding how Nr5a2 implicated in acute pancreatitis (AP) remains insufficient. Here, we explored this problem by using cellular AP model in both normal and Nr5a2 silenced AR42J pancreatic acinar cells. An in vitro cellular model of AP was established by stimulating AR42J cells with caerulein (CAE) for 24 h. Reduced Nr5a2 expression was observed in the CAE-treated cells. Nr5a2 silencing led to AP-like inflammation, with increased interleukin (IL)-1β, IL-6, and tumor necrosis factor (TNF)-α mRNA levels. In the cellular AP model, Nr5a2 silencing further increased IL-1β, IL-6, and TNF-α mRNA levels, as well as amylase activity. In addition, we found that Nr5a2 silencing did not affect IL-10 level under physiological conditions but inhibited the anti-inflammatory response of IL-10 in AP model. Moreover, in CAE-induced pancreatic inflammation, Nr5a2 silencing increased the apoptosis and necrosis of acinar cells and inhibited the proliferation of acinar cells, which has not been shown previously. Further experiments showed, for the first time, that Nr5a2 silencing downregulated the expression of β-catenin and its downstream target gene T-cell factor (TCF)-4 in the cellular AP model but increased the expression of nuclear factor (NF)-κB. In conclusion, in CAE-induced pancreatic inflammation, lower Nr5a2 level leads to downregulation of β-catenin and its downstream target gene TCF-4 and upregulation of NF-κB, which exacerbates the inflammatory response and cell damage and inhibits the proliferation and regeneration of acinar cells.

Cellular determinants and therapeutic implications of inflammation in pancreatic cancer

Inflammation is a hallmark of cancer. For pancreatic ductal adenocarcinoma (PDAC), malignant cells arise in the context of a brisk inflammatory cell infiltrate surrounded by dense fibrosis that is seen beginning at the earliest stages of cancer conception. This inflammatory and fibrotic milieu supports cancer cell escape from immune elimination and promotes malignant progression and metastatic spread to distant organs. Targeting this inflammatory reaction in PDAC by inhibiting or depleting pro-tumor elements and by engaging the potential of inflammatory cells to acquire anti-tumor activity has garnered strong research and clinical interest. Herein, we describe the current understanding of key determinants of inflammation in PDAC; mechanisms by which inflammation drives immune suppression; the impact of inflammation on metastasis, therapeutic resistance, and clinical outcomes; and strategies to intervene on inflammation for providing therapeutic benefit.

Prevention and Reversion of Pancreatic Tumorigenesis through a Differentiation-Based Mechanism

Activating mutations in Kras are nearly ubiquitous in human pancreatic cancer and initiate precancerous pancreatic intraepithelial neoplasia (PanINs) when induced in mouse acinar cells. PanINs normally take months to form but are accelerated by deletion of acinar cell differentiation factors such as Ptf1a, suggesting that loss of cell identity is rate limiting for pancreatic tumor initiation. Using a genetic mouse model that allows for independent control of oncogenic Kras and Ptf1a expression, we demonstrate that sustained Ptf1a is sufficient to prevent Kras-driven tumorigenesis, even in the presence of tumor-promoting inflammation. Furthermore, reintroducing Ptf1a into established PanINs reverts them to quiescent acinar cells in vivo. Similarly, Ptf1a re-expression in human pancreatic cancer cells inhibits their growth and colony-forming ability. Our results suggest that reactivation of an endogenous differentiation program can prevent and reverse oncogene-driven transformation in cells harboring tumor-driving mutations, introducing a potential paradigm for solid tumor prevention and treatment.

Signaling Networks That Control Cellular Plasticity in Pancreatic Tumorigenesis, Progression, and Metastasis

Pancreatic ductal adenocarcinoma is one of the deadliest cancers, and its incidence on the rise. The major challenges in overcoming the poor prognosis with this disease include late detection and the aggressive biology of the disease. Intratumoral heterogeneity; presence of a robust, reactive, and desmoplastic stroma; and the crosstalk between the different tumor components require complete understanding of the pancreatic tumor biology to better understand the therapeutic challenges posed by this disease. In this review, we discuss the processes involved during tumorigenesis encompassing the inherent plasticity of the transformed cells, development of tumor stroma crosstalk, and enrichment of cancer stem cell population during tumorigenesis.

Nr5a2 promotes tumor growth and metastasis of gastric cancer AGS cells by Wnt/beta-catenin signaling

Purpose: Nr5a2 (nuclear receptor subfamily 5 group A member 2, also known as LRH-1), which belongs to the NR5A (Ftz-F1) subfamily of nuclear receptors, is a key regulator in stem cell pluripotency and the development of several types of cancer. However, the data are controversial. Since Nr5a2 plays different roles in multiple types of cancer and the function of Nr5a2 in gastric cancer (GC) has not been revealed, we studied the role and molecular mechanism of Nr5a2 in GC. Methods: In this study, we have investigated the effect of Nr5a2 on tumor growth and metastasis by in vivo and in vitro models. Results: The results showed that knockdown of Nr5a2 could inhibit cell proliferation via arresting the cell cycle in the G2/M phase and suppress cell mobility through preventing the epithelial-mesenchymal transition (EMT) process in AGS cells. In addition, knockdown of Nr5a2 could suppress tumorigenesis and metastasis of AGS cells in vivo. We also demonstrated that knockdown of Nr5a2 inhibited cellular proliferation and mobility by suppressing the Wnt/beta-catenin signaling pathway. Conclusion: Nr5a2 may act as an oncogene in GC development. The EMT process and the Wnt/beta-catenin signaling pathway play an important role in the Nr5a2 induced GC development.

Cell of origin affects tumour development and phenotype in pancreatic ductal adenocarcinoma

OBJECTIVE

Pancreatic ductal adenocarcinoma (PDAC) is a highly aggressive tumour thought to arise from ductal cells via pancreatic intraepithelial neoplasia (PanIN) precursor lesions. Modelling of different genetic events in mice suggests both ductal and acinar cells can give rise to PDAC. However, the impact of cellular context alone on tumour development and phenotype is unknown.

DESIGN

We examined the contribution of cellular origin to PDAC development by inducing PDAC-associated mutations, KrasG12D expression and Trp53 loss, specifically in ductal cells (Sox9CreER;KrasLSL-G12D;Trp53flox/flox ('Duct:KPcKO ')) or acinar cells (Ptf1aCreER;KrasLSL-G12D;Trp53flox/flox ('Acinar:KPcKO ')) in mice. We then performed a thorough analysis of the resulting histopathological changes.

RESULTS

Both mouse models developed PDAC, but Duct:KPcKO mice developed PDAC earlier than Acinar:KPcKO mice. Tumour development was more rapid and associated with high-grade murine PanIN (mPanIN) lesions in Duct:KPcKO mice. In contrast, Acinar:KPcKO mice exhibited widespread metaplasia and low-grade as well as high-grade mPanINs with delayed progression to PDAC. Acinar-cell-derived tumours also had a higher prevalence of mucinous glandular features reminiscent of early mPanIN lesions.

CONCLUSION

These findings indicate that ductal cells are primed to form carcinoma in situ that become invasive PDAC in the presence of oncogenic Kras and Trp53 deletion, while acinar cells with the same mutations appear to require a prolonged period of transition or reprogramming to initiate PDAC. Our findings illustrate that PDAC can develop in multiple ways and the cellular context in which mutations are acquired has significant impact on precursor lesion initiation, disease progression and tumour phenotype.

Inflammation and de-differentiation in pancreatic carcinogenesis

Pancreatic cancer is a malignancy with an extremely poor prognosis. Chronic pancreatitis is a well-known risk factor for pancreatic cancer. Inflammation is thought to influence carcinogenesis through DNA damage and activation of intracellular signaling pathways. Many transcription factors and signaling pathways co-operate to determine and maintain cell identity at each phase of pancreatic organogenesis and cell differentiation. Recent studies have shown that carcinogenesis is promoted through the suppression of transcription factors related to differentiation. Pancreatitis also demonstrates transcriptional changes, suggesting that multifactorial epigenetic changes lead to impaired differentiation. Taken together, these factors may constitute an important framework for pancreatic carcinogenesis. In this review, we discuss the role of inflammation and de-differentiation in the development of pancreatic cancer, as well as the future of novel therapeutic applications.

Plasticity of differentiated cells in wound repair and tumorigenesis, part I: stomach and pancreas

For the last century or so, the mature, differentiated cells throughout the body have been regarded as largely inert with respect to their regenerative potential, yet recent research shows that they can become progenitor-like and re-enter the cell cycle. Indeed, we recently proposed that mature cells can become regenerative via a conserved set of molecular mechanisms ('paligenosis'), suggesting that a program for regeneration exists alongside programs for death (apoptosis) and division (mitosis). In two Reviews describing how emerging concepts of cellular plasticity are changing how the field views regeneration and tumorigenesis, we present the commonalities in the molecular and cellular features of plasticity at homeostasis and in response to injury in multiple organs. Here, in part 1, we discuss these advances in the stomach and pancreas. Understanding the extent of cell plasticity and uncovering its underlying mechanisms may help us refine important theories about the origin and progression of cancer, such as the cancer stem cell model, as well as the multi-hit model of tumorigenesis. Ultimately, we hope that the new concepts and perspectives on inherent cellular programs for regeneration and plasticity may open novel avenues for treating or preventing cancers.

Arid1a restrains Kras-dependent changes in acinar cell identity

Mutations in members of the SWI/SNF chromatin remodeling family are common events in cancer, but the mechanisms whereby disruption of SWI/SNF components alters tumorigenesis remain poorly understood. To model the effect of loss of function mutations in the SWI/SNF subunit Arid1a in pancreatic ductal adenocarcinoma (PDAC) initiation, we directed shRNA triggered, inducible and reversible suppression of Arid1a to the mouse pancreas in the setting of oncogenic Kras^G12D. Arid1a cooperates with Kras in the adult pancreas as postnatal silencing of Arid1a following sustained Kras^G12D expression induces rapid and irreversible reprogramming of acinar cells into mucinous PDAC precursor lesions. In contrast, Arid1a silencing during embryogenesis, concurrent with Kras^G12D activation, leads to retention of acinar cell fate. Together, our results demonstrate Arid1a as a critical modulator of Kras-dependent changes in acinar cell identity, and underscore an unanticipated influence of timing and genetic context on the effects of SWI/SNF complex alterations in epithelial tumorigenesis.

The pancreas produces many different hormones, as well as several substances important for digestion. To perform these roles, the pancreas contains different types of cells; for example, acinar cells make digestive enzymes that help to break down food. But, like other cells in the body, pancreatic cells can accumulate mutations in their DNA that cause them to divide, acquire an altered identity and form a cancerous tumor.

The DNA of cells is packed into a structure called chromatin. While the DNA sequence is essentially the same across all normal cells of a given individual, chromatin can be more or less compacted in the different cell types that comprise our body tissues. A collection of proteins called the SWI/SNF complex can reorganize the chromatin to change how tightly the DNA is packed. This determines which genes in the DNA are accessible and can be activated, and which ones cannot.

Around 25% of pancreatic cancers contain mutations in genes that produce proteins of the SWI/SNF complex. These mutations normally occur with an additional mutation that over-activates the gene that produces a potentially cancer-causing protein called Kras. Livshits et al. have now genetically engineered mice to investigate how one such SWI/SNF complex protein, called Arid1a, affects how pancreatic cancer develops using a genetic approach that made possible to temporarily halt the production of Arid1a in acinar cells by feeding these mice an antibiotic. The gene that produces Kras was also over-activated in the pancreases of the mice, making them more likely to develop cancer.

Within just two weeks of stopping the production of Arid1a, the acinar cells stopped producing digestive enzymes and started making other proteins that are typically found in cancerous cells, indicating that Arid1a is involved in maintaining the normal identity and activity of these cells. Restoring the ability of altered acinar cells to produce normal levels of Arid1a (by removing the mice from the antibiotic diet) did not reverse these changes. Biochemical experiments showed that acinar cells with reduced levels of Arid1a have altered chromatin. In particular, the genes that produce digestive enzymes, which are normally active in healthy pancreases, were less accessible in mice who had over-active Kras and reduced levels of Arid1a.

The results presented by Livshits et al. provide the first evidence of how alterations to Arid1a can lead to irreversible changes in the identity and activity of pancreatic acinar cells. These results will need to be carefully considered by researchers who are developing treatments for cancer patients with mutations in Arid1a and other SWI/SNF proteins. In particular, methods that attempt to restore the functions of absent SWI/SNF proteins to cancer cells are unlikely to treat the cancer successfully.

Induced PTF1a expression in pancreatic ductal adenocarcinoma cells activates acinar gene networks, reduces tumorigenic properties, and sensitizes cells to gemcitabine treatment

Pancreatic acinar cells synthesize, package, and secrete digestive enzymes into the duodenum to aid in nutrient absorption and meet metabolic demands. When exposed to cellular stresses and insults, acinar cells undergo a dedifferentiation process termed acinar-ductal metaplasia (ADM). ADM lesions with oncogenic mutations eventually give rise to pancreatic ductal adenocarcinoma (PDAC). In healthy pancreata, the basic helix-loop-helix (bHLH) factors MIST1 and PTF1a coordinate an acinar-specific transcription network that maintains the highly developed differentiation status of the cells, protecting the pancreas from undergoing a transformative process. However, when MIST1 and PTF1a gene expression is silenced, cells are more prone to progress to PDAC. In this study, we tested whether induced MIST1 or PTF1a expression in PDAC cells could (i) re-establish the transcriptional program of differentiated acinar cells and (ii) simultaneously reduce tumor cell properties. As predicted, PTF1a induced gene expression of digestive enzymes and acinar-specific transcription factors, while MIST1 induced gene expression of vesicle trafficking molecules as well as activation of unfolded protein response components, all of which are essential to handle the high protein production load that is characteristic of acinar cells. Importantly, induction of PTF1a in PDAC also influenced cancer-associated properties, leading to a decrease in cell proliferation, cancer stem cell numbers, and repression of key ATP-binding cassette efflux transporters resulting in heightened sensitivity to gemcitabine. Thus, activation of pancreatic bHLH transcription factors rescues the acinar gene program and decreases tumorigenic properties in pancreatic cancer cells, offering unique opportunities to develop novel therapeutic intervention strategies for this deadly disease.

Association between NR5A2 and the risk of pancreatic cancer, especially among Caucasians: a meta-analysis of case-control studies

Background

Previous studies have reported that nuclear receptor subfamily 5, group A, member 2 (NR5A2) polymorphisms (rs3790843 G>A, rs3790844 T>C, rs12029406 C>T) are associated with the risk of pancreatic cancer. However, the results of epidemiological investigations are still controversial. In order to explore its potential attributing factors, we pooled the updated literatures to evaluate the association between NR5A2 polymorphism and the risk of pancreatic cancer in this meta-analysis.

Materials and methods

Databases such as PubMed, Google Scholar and China National Knowledge Infrastructure were searched for eligible articles following strict inclusion and exclusion criteria (updated to November 18, 2017). Odds ratios (ORs) and 95% CIs were computed to assess the intensity of association. In addition, heterogeneity, sensitivity analysis and publication bias were explored. All statistical analyses were conducted by STATA 14.0.

Results

Our results showed that the rs3790843 (GA vs GG: OR=0.86, CI=0.76–0.98, P=0.992; GA+AA vs GG: OR=0.83, CI=0.73–0.94, P=0.950; A vs G: OR=0.85, CI=0.78–0.93, P=0.802), rs3790844 (CC vs TT: OR=0.65, CI=0.54–0.78, P=0.617; CC vs TT+CT: OR=0.73, CI=0.62–0.85, P=0.742; C vs T: OR=0.78, CI=0.73–0.84, P=0.555) and rs12029406 (TT vs CC: OR=0.73, CI=0.61–0.89, P=0.483; TT vs CC+CT: OR=0.78, CI=0.66–0.92, P=0.648; T vs C: OR=0.87, CI=0.79–0.95, P=0.837) polymorphisms were associated statistically with the risk of pancreatic cancer. Furthermore, the results of subgroup analysis showed that rs3790843 and rs3790844 polymorphisms were especially related to the risk of pancreatic cancer in Caucasian population.

Conclusion

Our results revealed that NR5A2 may have a protective effect on pancreatic cancer. However, more well-designed researches are needed to verify the relationship between NR5A2 polymorphisms and the risk of pancreatic cancer.

Investigating the role of transcription factors of pancreas development in pancreatic cancer

Pancreatic cancer (PC) is the seventh most common cause of cancer-related deaths worldwide that kills more than 300,000 people every year. Prognosis of PC is very poor with a five-year survival rate about 5%. The most common and highly observed type of PC is pancreatic ductal adenocarcinoma (PDAC). It is preceded by the progression of precursor lesions such as Pancreatic Intraepithelial Neoplasia (PanIN), Intraductal Papillary Neoplasm (IPMN) and Mucinous Cystic Neoplasm (MCN). PanIN is the most common among these premalignant lesions. Genes orchestrating the origin and differentiation of cells during organogenesis have the tendency to produce tumor cells in response to activating or inactivating mutations. Based on the following premise, we discuss the role of transcription factors (TFs) of pancreas development and cell fate differentiation in PC. Pancreas/duodenum homeobox protein 1 (PDX1), Pancreas transcription factor 1 subunit alpha (PTF1A), Nuclear receptor subfamily 5 group A member 2 (NR5A2), Hepatocyte nuclear factor 1-alpha (HNF1A) and Hepatocyte nuclear factor 1-beta (HNF1B) play vital role in the development and differentiation of pancreatic precursor cells. Mutated KRAS induces abnormalities in the regular function of these TFs which in turn cause abnormal cell growth and proliferation that leads to cancer. Thus, these TFs are highly susceptible for the origin of PC. Therefore, we propose that these TFs can be treated as therapeutic targets for the development of anticancer drugs.

Transcriptional variations in the wider peritumoral tissue environment of pancreatic cancer

Transcriptional profiling was performed on 452 RNA preparations isolated from various types of pancreatic tissue from tumour patients and healthy donors, with a particular focus on peritumoral samples. Pancreatic ductal adenocarcinomas (PDAC) and cystic tumours were most different in these non-tumorous tissues surrounding them, whereas the actual tumours exhibited rather similar transcript patterns. The environment of cystic tumours was transcriptionally nearly identical to normal pancreas tissue. In contrast, the tissue around PDAC behaved a lot like the tumour, indicating some kind of field defect, while showing far less molecular resemblance to both chronic pancreatitis and healthy tissue. This suggests that the major pathogenic difference between cystic and ductal tumours may be due to their cellular environment rather than the few variations between the tumours. Lack of correlation between DNA methylation and transcript levels makes it unlikely that the observed field defect in the peritumoral tissue of PDAC is controlled to a large extent by such epigenetic regulation. Functionally, a strikingly large number of autophagy-related transcripts was changed in both PDAC and its peritumoral tissue, but not in other pancreatic tumours. A transcription signature of 15 autophagy-related genes was established that permits a prognosis of survival with high accuracy and indicates the role of autophagy in tumour biology.

Transcriptional regulation by NR5A2 links differentiation and inflammation in the pancreas

Chronic inflammation increases the risk of several cancer types. The current notion is that the control of inflammatory responses relies on transcriptional networks distinct from those involved in cell differentiation ^1–3. The orphan nuclear receptor NR5A2 participates in a wide variety of processes including cholesterol and glucose metabolism in the liver, resolution of ER stress, intestinal glucocorticoid production, pancreatic development, and acinar differentiation ^4–8. Single nucleotide polymorphisms (SNPs) in the vicinity of NR5A2 have been associated with the risk of pancreatic adenocarcinoma (PDAC) through genome wide association studies ^9,10. In mice, Nr5a2 heterozygosity sensitizes the pancreas to damage, impairs regeneration, and cooperates with mutant KRas in tumor progression ¹¹. Through global transcriptomic analysis, we describe here an epithelial cell-autonomous basal pre-inflammatory state in the pancreas of Nr5a2^+/− mice that is reminiscent of early stages of pancreatitis-induced inflammation and is conserved in histologically normal human pancreata with reduced NR5A2 mRNA expression. In Nr5a2^+/− mice, Nr5a2 undergoes a dramatic transcriptional switch relocating from differentiation-specific to inflammatory genes thereby promoting AP-1-dependent gene transcription. Pancreatic deletion of c-Jun rescues the pre-inflammatory phenotype, Nr5a2 binding to inflammatory gene promoters, and the defective regenerative response to damage. These findings support the notion that, in the pancreas, the same transcriptional networks involved in differentiation-specific functions suppress inflammatory programmes. These networks can be subverted to foster inflammation upon genetic or environmental constraints.

Nuclear Receptor LRH-1 Functions to Promote Castration-Resistant Growth of Prostate Cancer via Its Promotion of Intratumoral Androgen Biosynthesis

Targeting of steroidogenic enzymes (e.g., abiraterone acetate targeting CYP17A1) has been developed as a novel therapeutic strategy against metastatic castration-resistant prostate cancer (CRPC). However, resistance to steroidal inhibitors inevitably develops in patients, the mechanisms of which remain largely unknown. Liver receptor homolog-1 (LRH-1, NR5A2) is a nuclear receptor, originally characterized as an important regulator of some liver-specific metabolic genes. Here, we report that LRH-1, which exhibited an increased expression pattern in high-grade prostate cancer and CRPC xenograft models, functions to promote de novo androgen biosynthesis via its direct transactivation of several key steroidogenic enzyme genes, elevating intratumoral androgen levels and reactivating AR signaling in CRPC xenografts as well as abiraterone-treated CRPC tumors. Pharmacologic inhibition of LRH-1 activity attenuated LRH-1-mediated androgen deprivation and anti-androgen resistance of prostate cancer cells. Our findings not only demonstrate the significant role of LRH-1 in the promotion of intratumoral androgen biosynthesis in CRPC via its direct transcriptional control of steroidogenesis, but also suggest targeting LRH-1 could be a potential therapeutic strategy for CRPC management.Significance: These findings not only demonstrate the significant role of the nuclear receptor LRH-1 in the promotion of intratumoral androgen biosynthesis in CRPC via its direct transcriptional control of steroidogenesis, but also suggest targeting LRH-1 could be a potential therapeutic strategy for CRPC management. Cancer Res; 78(9); 2205-18. ©2018 AACR.

Differentiation and Inflammation: 'Best Enemies' in Gastrointestinal Carcinogenesis

While recent studies demonstrate that cancer can arise from mutant stem cells, this hypothesis does not explain why tissues without defined stem cell populations are susceptible to inflammation-driven tumorigenesis. We propose that chronic inflammatory diseases, such as colitis and pancreatitis, predispose to gastrointestinal (GI) adenocarcinoma by reprogramming differentiated cells. Focusing on colon and pancreas, we discuss recently discovered connections between inflammation and loss of cell differentiation, and propose that dysregulation of cell fate may be a novel rate-limiting step of tumorigenesis. We review studies identifying differentiation mechanisms that limit tumor initiation and that, upon reactivation, can prevent or revert the cancer cell transformed phenotype. Together, these findings suggest that differentiation-targeted treatments hold promise as a therapeutic strategy in GI cancer.

Inherited pancreatic cancer

Pancreatic cancers arise through a series of genetic events both inherited and acquired. Inherited genetic changes, both high penetrance and low penetrance, are an important component of pancreatic cancer risk, and may be used to characterize populations who will benefit from early detection. Furthermore, pancreatic cancer patients with inherited mutations may be particularly sensitive to certain targeted agents, providing an opportunity to personalized treatment. Family history of pancreatic cancer is one of the strongest risk factors for the disease, and is associated with an increased risk of caners at other sites, including but not limited to breast, ovarian and colorectal cancer. The goal of this chapter is to discuss the importance of family history of pancreatic cancer, and the known genes that account for a portion of the familial clustering of pancreatic cancer.

Analyses of reaction norms reveal new chromosome regions associated with tick resistance in cattle

Despite single nucleotide polymorphism (SNP) availability and frequent cost reduction has allowed genome-wide association studies even in complex traits as tick resistance, the use of this information source in SNP by environment interaction context is unknown for many economically important traits in cattle. We aimed at identifying putative genomic regions explaining differences in tick resistance in Hereford and Braford cattle under SNP by environment point of view as well as to identify candidate genes derived from outliers/significant markers. The environment was defined as contemporary group means of tick counts, since they seemed to be the most appropriate entities to describe the environmental gradient in beef cattle. A total of 4363 animals having tick counts (n=10 673) originated from 197 sires and 3966 dams were used. Genotypes were acquired on 3591 of these cattle. From top 1% SNPs (410) having the greatest effects in each environment, 75 were consistently relevant in all environments, which indicated SNP by environment interaction. The outliers/significant SNPs were mapped on chromosomes 1, 2, 5, 6, 7, 9, 11, 13, 14, 15, 16, 18, 21, 23, 24, 26 and 28, and potential candidate genes were detected across environments. The presence of SNP by environment interaction for tick resistance indicates that genetic expression of resistance depends upon tick burden. Markers with major portion of genetic variance explained across environments appeared to be close to genes with different direct or indirect functions related to immune system, inflammatory process and mechanisms of tissue destruction/repair, such as energy metabolism and cell differentiation.

Acinar cell plasticity and development of pancreatic ductal adenocarcinoma

Acinar cells in the adult pancreas show high plasticity and can undergo transdifferentiation to a progenitor-like cell type with ductal characteristics. This process, termed acinar-to-ductal metaplasia (ADM), is an important feature facilitating pancreas regeneration after injury. Data from animal models show that cells that undergo ADM in response to oncogenic signalling are precursors for pancreatic intraepithelial neoplasia lesions, which can further progress to pancreatic ductal adenocarcinoma (PDAC). As human pancreatic adenocarcinoma is often diagnosed at a stage of metastatic disease, understanding the processes that lead to its initiation is important for the discovery of markers for early detection, as well as options that enable an early intervention. Here, the critical determinants of acinar cell plasticity are discussed, in addition to the intracellular and extracellular signalling events that drive acinar cell metaplasia and their contribution to development of PDAC.

Effect of NR5A2 inhibition on pancreatic cancer stem cell (CSC) properties and epithelial-mesenchymal transition (EMT) markers

NR5A2 (aka LRH-1) has been identified as a pancreatic cancer susceptibility gene with missing biological link. This study aims to demonstrate expression and potential role of NR5A2 in pancreatic cancer. NR5A2 expression was quantified in resected pancreatic ductal adenocarcinomas and the normal adjacent tissues of 134 patients by immunohistochemistry. The intensity and extent of NR5A2 staining was quantified and analyzed in association with overall survival (OS). The impact of NR5A2 knockdown on pancreatic cancer stem cell (CSC) properties and epithelial-mesenchymal transition (EMT) markers was examined in cancer cells using RT-PCR and Western Blot. NR5A2 was overexpressed in pancreatic tumors, the IHC-staining H score (mean ± SE) was 96.4 ± 8.3 in normal versus 137.9 ± 8.2 in tumor tissues (P < 0.0001). Patients with a higher NR5A2 expression had a median survival time 18.4 months compared to 23.7 months for those with low IHC H scores (P = 0.019). The hazard ratio of death (95% confidence interval) was 1.60 (1.07-2.41) after adjusting for disease stage and tumor grade (P = 0.023). NR5A2 was highly expressed in pancreatic cancer sphere forming cells. NR5A2-inhibition by siRNA was associated with reduced sphere formation and decreased levels of CSCs markers NANOG, OCT4, LIN28B, and NOTCH1. NR5A2 knockdown also resulted in reduced expression of FGB, MMP2, MMP3, MMMP9, SNAIL, and TWIST, increased expression of epithelial markers E-cadherin and β-catenin, and a lower expression of mesenchymal marker Vimentin. Taken together, our findings suggest that NR5A2 could play a role in CSC stemness and EMT in pancreatic cancer, which may contribute to the worse clinical outcome.