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Nature Sep 2021Pancreatic ductal adenocarcinoma (PDAC) is one of the leading causes of cancer deaths worldwide. Studies in human tissues and in mouse models have suggested that for...
Pancreatic ductal adenocarcinoma (PDAC) is one of the leading causes of cancer deaths worldwide. Studies in human tissues and in mouse models have suggested that for many cancers, stem cells sustain early mutations driving tumour development. For the pancreas, however, mechanisms underlying cellular renewal and initiation of PDAC remain unresolved. Here, using lineage tracing from the endogenous telomerase reverse transcriptase (Tert) locus, we identify a rare TERT-positive subpopulation of pancreatic acinar cells dispersed throughout the exocrine compartment. During homeostasis, these TERT acinar cells renew the pancreas by forming expanding clones of acinar cells, whereas randomly marked acinar cells do not form these clones. Specific expression of mutant Kras in TERT acinar cells accelerates acinar clone formation and causes transdifferentiation to ductal pre-invasive pancreatic intraepithelial neoplasms by upregulating Ras-MAPK signalling and activating the downstream kinase ERK (phospho-ERK). In resected human pancreatic neoplasms, we find that foci of phospho-ERK-positive acinar cells are common and frequently contain activating KRAS mutations, suggesting that these acinar regions represent an early cancer precursor lesion. These data support a model in which rare TERT acinar cells may sustain KRAS mutations, driving acinar cell expansion and creating a field of aberrant cells initiating pancreatic tumorigenesis.
Topics: Acinar Cells; Animals; Carcinogenesis; Carcinoma, Pancreatic Ductal; Cell Transdifferentiation; Cell Transformation, Neoplastic; Homeostasis; Humans; MAP Kinase Signaling System; Mice; Mutation; Pancreas; Pancreatic Neoplasms; Proto-Oncogene Proteins p21(ras); Telomerase
PubMed: 34526722
DOI: 10.1038/s41586-021-03916-2 -
Gastroenterology Jun 2024Acinar cells produce digestive enzymes that impede transcriptomic characterization of the exocrine pancreas. Thus, single-cell RNA-sequencing studies of the pancreas...
BACKGROUND & AIMS
Acinar cells produce digestive enzymes that impede transcriptomic characterization of the exocrine pancreas. Thus, single-cell RNA-sequencing studies of the pancreas underrepresent acinar cells relative to histological expectations, and a robust approach to capture pancreatic cell responses in disease states is needed. We sought to innovate a method that overcomes these challenges to accelerate study of the pancreas in health and disease.
METHODS
We leverage FixNCut, a single-cell RNA-sequencing approach in which tissue is reversibly fixed with dithiobis(succinimidyl propionate) before dissociation and single-cell preparation. We apply FixNCut to an established mouse model of acute pancreatitis, validate findings using GeoMx whole transcriptome atlas profiling, and integrate our data with prior studies to compare our method in both mouse and human pancreas datasets.
RESULTS
FixNCut achieves unprecedented definition of challenging pancreatic cells, including acinar and immune populations in homeostasis and acute pancreatitis, and identifies changes in all major cell types during injury and recovery. We define the acinar transcriptome during homeostasis and acinar-to-ductal metaplasia and establish a unique gene set to measure deviation from normal acinar identity. We characterize pancreatic immune cells, and analysis of T-cell subsets reveals a polarization of the homeostatic pancreas toward type-2 immunity. We report immune responses during acute pancreatitis and recovery, including early neutrophil infiltration, expansion of dendritic cell subsets, and a substantial shift in the transcriptome of macrophages due to both resident macrophage activation and monocyte infiltration.
CONCLUSIONS
FixNCut preserves pancreatic transcriptomes to uncover novel cell states during homeostasis and following pancreatitis, establishing a broadly applicable approach and reference atlas for study of pancreas biology and disease.
Topics: Animals; Pancreatitis; Homeostasis; Transcriptome; Single-Cell Analysis; Humans; Acinar Cells; Mice; Disease Models, Animal; Pancreas; Gene Expression Profiling; RNA-Seq; Acute Disease; Pancreas, Exocrine; Macrophages; Metaplasia; Mice, Inbred C57BL
PubMed: 38325760
DOI: 10.1053/j.gastro.2024.01.043 -
Biochimica Et Biophysica Acta. Reviews... Mar 2022Pancreatic ductal metaplasia (PDM) is the transformation of potentially many type of cells in pancreas into ductal or ductal-like cells, which eventually replace the... (Review)
Review
Pancreatic ductal metaplasia (PDM) is the transformation of potentially many type of cells in 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 and cellular stimuli and stresses. Acinar to ductal metaplasia (ADM) is the predominant form of ductal metaplasia in pancreas. The cellular heterogeneity of PDM informs the differences in cellular origin, triggering events, functional subpopulations and evolution pathways of PDM. Currently it remains uncertain what are the exact cellular origins and functional significance of PDM, and how this process is regulated at cellular and molecular levels. The development of PDM to atypical hyperplasia is an important risk factor for pancreatic precursors, including intraepithelial neoplasia (PanIN), and pancreatic ductal adenocarcinoma (PDAC). Otherwise, the cellular plasticity in PDM contribute to the regeneration of both exocrine and endocrine components of pancreas. This Review will systematically describe current knowledge on the understanding of PDM biology with an emphasis on its underlying mechanisms and implications in pancreatic regeneration, inflammation and tumorigenesis.
Topics: Acinar Cells; Carcinoma, Pancreatic Ductal; Humans; Metaplasia; Pancreas; Pancreatic Neoplasms
PubMed: 35176433
DOI: 10.1016/j.bbcan.2022.188698 -
American Journal of Physiology.... Mar 2020PAK4 is the only member of the Group II p21-activated kinases (PAKs) present in rat pancreatic acinar cells and is activated by gastrointestinal...
PAK4 is the only member of the Group II p21-activated kinases (PAKs) present in rat pancreatic acinar cells and is activated by gastrointestinal hormones/neurotransmitters stimulating PLC/cAMP and by various pancreatic growth factors. However, little is known of the role of PAK4 activation in cellular signaling cascades in pancreatic acinar cells. In the present study, we examined the role of PAK4's participation in five different cholecystokinin-8 (CCK-8)-stimulated signaling pathways (PI3K/Akt, MAPK, focal adhesion kinase, GSK3, and β-catenin), which mediate many of its physiological acinar-cell effects, as well as effects in pathophysiological conditions. To define PAK4's role, the effect of two different PAK4 inhibitors, PF-3758309 and LCH-7749944, was examined under experimental conditions that only inhibited PAK4 activation and not activation of the other pancreatic PAK, Group I PAK2. The inhibitors' effects on activation of these five signaling cascades by both physiological and pathophysiological concentrations of CCK, as well as by 12--tetradecanoylphobol-13-acetate (TPA), a PKC-activator, were examined. CCK/TPA activation of focal adhesion kinases(PYK2/p125) and the accompanying adapter proteins (paxillin/p130), Mek1/2, and p44/42, but not c-Raf or other MAPKs (JNK/p38), were mediated by PAK4. Activation of PI3K/Akt/p70s6K was independent of PAK4, whereas GSK3 and β-catenin stimulation was PAK4-dependent. These results, coupled with recent studies showing PAK4 is important in pancreatic fluid/electrolyte/enzyme secretion and acinar cell growth, show that PAK4 plays an important role in different cellular signaling cascades, which have been shown to mediate numerous physiological and pathophysiological processes in pancreatic acinar cells. In pancreatic acinar cells, cholecystokinin (CCK) or 12--tetradecanoylphobol-13-acetate (TPA) activation of focal adhesion kinases (p125,PYK2) and its accompanying adapter proteins, p130CAS/paxillin; Mek1/2, p44/42, GSK3, and β-catenin are mediated by PAK4. PI3K/Akt/p70s6K, c-Raf, JNK, or p38 pathways are independent of PAK4 activation.
Topics: Acinar Cells; Animals; Crk-Associated Substrate Protein; Enzyme Activation; Enzyme Activators; Extracellular Signal-Regulated MAP Kinases; Focal Adhesion Kinase 1; Focal Adhesion Kinase 2; Glycogen Synthase Kinase 3; Male; Mitogen-Activated Protein Kinase Kinases; Pancreas, Exocrine; Paxillin; Protein Kinase Inhibitors; Rats, Sprague-Dawley; Signal Transduction; beta Catenin; p21-Activated Kinases
PubMed: 31984786
DOI: 10.1152/ajpgi.00229.2019 -
Cell Metabolism Dec 2023The rising pancreatic cancer incidence due to obesity and type 2 diabetes is closely tied to hyperinsulinemia, an independent cancer risk factor. Previous studies...
The rising pancreatic cancer incidence due to obesity and type 2 diabetes is closely tied to hyperinsulinemia, an independent cancer risk factor. Previous studies demonstrated reducing insulin production suppressed pancreatic intraepithelial neoplasia (PanIN) pre-cancerous lesions in Kras-mutant mice. However, the pathophysiological and molecular mechanisms remained unknown, and in particular it was unclear whether hyperinsulinemia affected PanIN precursor cells directly or indirectly. Here, we demonstrate that insulin receptors (Insr) in Kras-expressing pancreatic acinar cells are dispensable for glucose homeostasis but necessary for hyperinsulinemia-driven PanIN formation in the context of diet-induced hyperinsulinemia and obesity. Mechanistically, this was attributed to amplified digestive enzyme protein translation, triggering of local inflammation, and PanIN metaplasia in vivo. In vitro, insulin dose-dependently increased acinar-to-ductal metaplasia formation in a trypsin- and Insr-dependent manner. Collectively, our data shed light on the mechanisms connecting obesity-driven hyperinsulinemia and pancreatic cancer development.
Topics: Mice; Animals; Proto-Oncogene Proteins p21(ras); Receptor, Insulin; Diabetes Mellitus, Type 2; Pancreatic Neoplasms; Acinar Cells; Carcinoma in Situ; Inflammation; Hyperinsulinism; Metaplasia; Obesity; Insulins
PubMed: 37913768
DOI: 10.1016/j.cmet.2023.10.003 -
Advanced Science (Weinheim,... Sep 2023Mitochondrial function impairment due to abnormal opening of the mitochondrial permeability transition pore (MPTP) is considered the central event in acute pancreatitis;...
Mitochondrial function impairment due to abnormal opening of the mitochondrial permeability transition pore (MPTP) is considered the central event in acute pancreatitis; however, therapeutic choices for this condition remain controversial. Mesenchymal stem cells (MSCs) are a family member of stem cells with immunomodulatory and anti-inflammatory capabilities that can mitigate damage in experimental pancreatitis. Here, it is shown that MSCs deliver hypoxia-treated functional mitochondria to damaged pancreatic acinar cells (PACs) via extracellular vesicles (EVs), which reverse the metabolic function of PACs, maintain ATP supply, and exhibit an excellent injury-inhibiting effect. Mechanistically, hypoxia inhibits superoxide accumulation in the mitochondria of MSCs and upregulates the membrane potential, which is internalized into PACs via EVs, thus, remodeling the metabolic state. In addition, cargocytes constructed via stem cell denucleation as mitochondrial vectors are shown to exert similar therapeutic effects to MSCs. These findings reveal an important mechanism underlying the role of mitochondria in MSC therapy and offer the possibility of applying mitochondrial therapy to patients with severe acute pancreatitis.
Topics: Acinar Cells; Acute Disease; Adenosine Triphosphate; Bile Acids and Salts; Cell Hypoxia; Cellular Reprogramming; Extracellular Vesicles; Membrane Potential, Mitochondrial; Mesenchymal Stem Cells; Mitochondria; Mitochondrial Permeability Transition Pore; Pancreas; Pancreatitis; Paracrine Communication; Superoxides; Umbilical Cord; Humans
PubMed: 37409821
DOI: 10.1002/advs.202207691 -
Gastroenterology May 2019Premature activation of digestive enzymes in the pancreas has been linked to development of pancreatitis for more than a century. Recent development of novel models to... (Review)
Review
Premature activation of digestive enzymes in the pancreas has been linked to development of pancreatitis for more than a century. Recent development of novel models to study the role of pathologic enzyme activation has led to advances in our understanding of the mechanisms of pancreatic injury. Colocalization of zymogen and lysosomal fraction occurs early after pancreatitis-causing stimulus. Cathepsin B activates trypsinogen in these colocalized organelles. Active trypsin increases permeability of these organelles resulting in leakage of cathepsin B into the cytosol leading to acinar cell death. Although trypsin-mediated cell death leads to pancreatic injury in early stages of pancreatitis, multiple parallel mechanisms, including activation of inflammatory cascades, endoplasmic reticulum stress, autophagy, and mitochondrial dysfunction in the acinar cells are now recognized to be important in driving the profound systemic inflammatory response and extensive pancreatic injury seen in acute pancreatitis. Chymotrypsin, another acinar protease, has recently been shown be play critical role in clearance of pathologically activated trypsin protecting against pancreatic injury. Mutations in trypsin and other genes thought to be associated with pathologic enzyme activation (such as serine protease inhibitor 1) have been found in familial forms of pancreatitis. Sustained intra-acinar activation of nuclear factor κB pathway seems to be key pathogenic mechanism in chronic pancreatitis. Better understanding of these mechanisms will hopefully allow us to improve treatment strategies in acute and chronic pancreatitis.
Topics: Acinar Cells; Animals; Cell Death; Enzyme Activation; Genetic Predisposition to Disease; Humans; Inflammation Mediators; Mutation; Pancreas, Exocrine; Pancreatitis; Phenotype; Signal Transduction; Trypsin; Trypsinogen
PubMed: 30776339
DOI: 10.1053/j.gastro.2019.01.268 -
Journal of Gastroenterology Jul 2016Acute pancreatitis is a serious medical disorder with no current therapies directed to the molecular pathogenesis of the disorder. Inflammation, inappropriate... (Review)
Review
BACKGROUND
Acute pancreatitis is a serious medical disorder with no current therapies directed to the molecular pathogenesis of the disorder. Inflammation, inappropriate intracellular activation of digestive enzymes, and parenchymal acinar cell death by necrosis are the critical pathophysiologic processes of acute pancreatitis. Thus, it is necessary to elucidate the key molecular signals that mediate these pathobiologic processes and develop new therapeutic strategies to attenuate the appropriate signaling pathways in order to improve outcomes for this disease. A novel serine/threonine protein kinase D (PKD) family has emerged as key participants in signal transduction, and this family is increasingly being implicated in the regulation of multiple cellular functions and diseases.
METHODS
This review summarizes recent findings of our group and others regarding the signaling pathway and the biological roles of the PKD family in pancreatic acinar cells. In particular, we highlight our studies of the functions of PKD in several key pathobiologic processes associated with acute pancreatitis in experimental models.
RESULTS
Our findings reveal that PKD signaling is required for NF-κB activation/inflammation, intracellular zymogen activation, and acinar cell necrosis in rodent experimental pancreatitis. Novel small-molecule PKD inhibitors attenuate the severity of pancreatitis in both in vitro and in vivo experimental models. Further, this review emphasizes our latest advances in the therapeutic application of PKD inhibitors to experimental pancreatitis after the initiation of pancreatitis.
CONCLUSIONS
These novel findings suggest that PKD signaling is a necessary modulator in key initiating pathobiologic processes of pancreatitis, and that it constitutes a novel therapeutic target for treatments of this disorder.
Topics: Acinar Cells; Humans; Pancreatitis; Protein Serine-Threonine Kinases; Signal Transduction
PubMed: 26879861
DOI: 10.1007/s00535-016-1175-3 -
Cytokine & Growth Factor Reviews 2023Pancreatic fibrosis is caused by excessive deposition of extracellular matrixes of collagen and fibronectin in the pancreatic tissue as a result of repeated injury often... (Review)
Review
Pancreatic fibrosis is caused by excessive deposition of extracellular matrixes of collagen and fibronectin in the pancreatic tissue as a result of repeated injury often seen in patients with chronic pancreatic diseases. The most common causative conditions include inborn errors of metabolism, chemical toxicity and autoimmune disorders. Its pathophysiology is highly complex, including acinar cell injury, acinar stress response, duct dysfunction, pancreatic stellate cell activation, and persistent inflammatory response. However, the specific mechanism remains to be fully clarified. Although the current therapeutic strategies targeting pancreatic stellate cells show good efficacy in cell culture and animal models, they are not satisfactory in the clinic. Without effective intervention, pancreatic fibrosis can promote the transformation from pancreatitis to pancreatic cancer, one of the most lethal malignancies. In the normal pancreas, the acinar component accounts for 82% of the exocrine tissue. Abnormal acinar cells may activate pancreatic stellate cells directly as cellular source of fibrosis or indirectly via releasing various substances and initiate pancreatic fibrosis. A comprehensive understanding of the role of acinar cells in pancreatic fibrosis is critical for designing effective intervention strategies. In this review, we focus on the role of and mechanisms underlying pancreatic acinar injury in pancreatic fibrosis and their potential clinical significance.
Topics: Animals; Humans; Acinar Cells; Pancreas; Pancreatic Diseases; Pancreatitis; Chronic Disease; Fibrosis
PubMed: 37291030
DOI: 10.1016/j.cytogfr.2023.05.003 -
Cell Death & Disease Aug 2023Acinar cell dedifferentiation is one of the most notable features of acute and chronic pancreatitis. It can also be the initial step that facilitates pancreatic cancer...
Acinar cell dedifferentiation is one of the most notable features of acute and chronic pancreatitis. It can also be the initial step that facilitates pancreatic cancer development. In the present study, we further decipher the precise mechanisms and regulation using primary human cells and murine experimental models. Our RNAseq analysis indicates that, in both species, early acinar cell dedifferentiation is accompanied by multiple pathways related to cell survival that are highly enriched, and where SLC7A11 (xCT) is transiently upregulated. xCT is the specific subunit of the cystine/glutamate antiporter system x. To decipher its role, gene silencing, pharmacological inhibition and a knock-out mouse model were used. Acinar cells with depleted or reduced xCT function show an increase in ferroptosis relating to lipid peroxidation. Lower glutathione levels and more lipid ROS accumulation could be rescued by the antioxidant N-acetylcysteine or the ferroptosis inhibitor ferrostatin-1. In caerulein-induced acute pancreatitis in mice, xCT also prevents lipid peroxidation in acinar cells. In conclusion, during stress, acinar cell fate seems to be poised for avoiding several forms of cell death. xCT specifically prevents acinar cell ferroptosis by fueling the glutathione pool and maintaining ROS balance. The data suggest that xCT offers a druggable tipping point to steer the acinar cell fate in stress conditions.
Topics: Humans; Animals; Mice; Acinar Cells; Acute Disease; Ferroptosis; Pancreatitis; Reactive Oxygen Species; Glutamic Acid
PubMed: 37604805
DOI: 10.1038/s41419-023-06063-w