Dedifferentiation Of Acinar Cells Research Articles

Abstract 3378: Acinar cell susceptibility for tumor development in the pancreas: Targeting the critical regulators for therapy

Abstract Acinar to ductal metaplasia (ADM) or acinar cell dedifferentiation is one of the most notable features of chronic pancreatitis. It is also considered the initial step of pancreatic cancer development when oncogenic mutations accumulate. However, its precise mechanism and regulatory pathways remain unclear. This study profiled the transcriptome of dedifferentiated acinar cells from both humans and mice. Differential expression analysis integrated with a systematic literature search revealed several potential regulators (e.g., GDF15, GFRA1, MXRA5, CXCL17), of which the expression pattern over time was validated by qRT-PCR. We also focused on multiple conserved pathways of cell survival, among which SLC7A11 (xCT) is transiently upregulated in both species. The xCT subunit, integral to the cystine/glutamate antiporter system xc-, plays a critical role in cell survival across various cell types. To elucidate its role in acinar dedifferentiation, we employed gene silencing, pharmacological inhibition, and a knock-out mouse model. Acinar cells with diminished xCT function exhibit increased ferroptosis linked to lipid peroxidation. Antioxidants such as N-acetylcysteine and ferroptosis inhibitors like Ferrostatin-1 can mitigate lower glutathione levels and lipid ROS accumulation. Similarly, in mouse acute pancreatitis, xCT prevents lipid peroxidation. Our findings indicate that xCT fuels the glutathione pool and maintains ROS balance during ADM, thereby preventing pancreatic acinar cells from ferroptosis, a form of cell death rarely reported in relation to ADM. Next to xCT, a future and similar comprehensive study of the aforementioned genes could provide valuable insights into the dynamic changes that occur during acinar cell dedifferentiation and pave the way to the discovery of new intervention targets to suppress tumorigenesis in chronic pancreatitis. Citation Format: Zhaolong Pan, Jan-Lars Van den Bossche, Eva Rodriguez-Aznar, Pauline Janssen, Olaya Lara, Gamze Ates, Ann Massie, Diedert Luc De Paep, Isabelle Houbracken, Marco Mambretti, Ilse Rooman. Acinar cell susceptibility for tumor development in the pancreas: Targeting the critical regulators for therapy [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 3378.

Pancreatic acinar cell fate relies on system xC- to prevent ferroptosis during stress

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 xC-. 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.

The sialyltransferase ST6Gal1 is upregulated in a cytokine‐mediated manner during pancreatitis

Pancreatitis is a life‐threatening medical disorder that occurs when abnormally activated pancreatic enzymes damage surrounding pancreatic acinar cells, leading to the release of several pro‐inflammatory cytokines. Subsequently, inflammation of the pancreas promotes the dedifferentiation of acinar cells towards a ductal‐like, progenitor phenotype, to heal from pancreatic injury, in a process known as acinar to ductal metaplasia (ADM). Recent studies by our group suggest that the sialyltransferase, ST6Gal1 promotes ADM. ST6Gal1 adds sialic acid to N‐glycosylated surface receptors and thereby regulates cell signaling and phenotype. In the current study, we report the novel finding that ST6Gal1 is upregulated in the pancreatic tissues of patients with chronic pancreatitis and mice with experimental pancreatitis, whereas ST6Gal1 expression is undetectable in normal acinar cells. These results are the first to show stark modulation of ST6Gal1 within pancreatic inflammation. While the upregulation of ST6Gal1 has been noted across multiple cancers, the mechanisms by which ST6Gal1 expression is modulated within an inflammatory milieu are not well understood. To evaluate inflammation‐induced ST6Gal1 upregulation, we injected mice with cerulein to evoke pancreatitis. We first examined levels of pro‐inflammatory cytokines through immunohistochemistry in cerulein‐treated mice and observed striking increases in the release of both IL‐6 and IL‐1β. Accordingly, we proceeded to treat multiple pancreatic acinar cell line models with IL‐6 and IL‐1β to assess their respective capability to upregulate ST6Gal1. These two cytokines stimulated increases in ST6Gal1 mRNA and protein in all cell models. It's known that there are three major isoforms of ST6Gal1, each driven by a different promoter; thus, we investigated which of the three isoforms was increased following cytokine treatment. We found that the isoform driven by the P3 promoter, a ubiquitously expressed isoform known as “YZ”, was the only isoform seen to be upregulated following cytokine treatment. To further understand the mechanisms by which IL‐6 and IL‐1β mediate their upregulation of ST6Gal1, we used an online transcription factor binding predictor to assess which transcription factors bind to the P3 promoter of the YZ isoform of ST6Gal1. On this P3 promoter, we found binding sites for STAT3, which is activated by IL‐6, and NF‐κB, which is activated by IL‐1β. Furthermore, we observed STAT3 and NF‐κB pathway activation following cytokine treatment. Importantly, STAT3 and NF‐κB inhibitors blocked cytokine‐induced ST6Gal1 upregulation in multiple cell models, thus confirming that IL‐6 and IL‐1β mediated their upregulation of the YZ isoform through the STAT3 and NF‐κB pathways, respectively. Taken together, these results not only show ST6Gal1 modulation within pancreatitis but detail the mechanisms by which this occurs, thus providing significant insight into an area of research that has not been well characterized.

SULF2 enhances GDF15-SMAD axis to facilitate the initiation and progression of pancreatic cancer

Owing to the lack of early diagnosis, pancreatic ductal adenocarcinoma (PDAC) remains one of the most lethal tumours. Because acinar-to-ductal metaplasia (ADM) is a critical process to pancreatic regeneration and PDAC initiation, we applied GSE65146, a dataset composed of transcripts at different time points in wild-type and KrasG12D mutant mice upon pancreatitis induction, to obtain regeneration- and tumour initiation-related genes. By overlapping with genes differentially expressed in human PDAC, we defined the initiation- and progression-related genes, and the most prognostic gene, SULF2, was selected for further verification. By using multiple PDAC genetically engineered murine models (GEMMs), we further verified that the expression of SULF2 was increased at the ADM and PDAC stages. Functionally, SULF2 was able to promote the dedifferentiation of acinar cells as well as the metastatic ability of PDAC. Additionally, our study revealed that SULF2 could enhance TGFβ-SMAD signalling via GDF15. More importantly, serum SULF2 was elevated in patients with PDAC, and in combination with CA19-9, it provided a better method for PDAC diagnosis. Herein, our study screened out key genes for the initiation and progression of PDAC, providing potential indicators for the diagnosis of the disease.

Necroptosis protects against exacerbation of acute pancreatitis

The sensing of various extrinsic stimuli triggers the receptor-interacting protein kinase-3 (RIPK3)-mediated signaling pathway, which leads to mixed-lineage kinase-like (MLKL) phosphorylation followed by necroptosis. Although necroptosis is a form of cell death and is involved in inflammatory conditions, the roles of necroptosis in acute pancreatitis (AP) remain unclear. In the current study, we administered caerulein to Ripk3- or Mlkl-deficient mice (Ripk3−/− or Mlkl−/− mice, respectively) and assessed the roles of necroptosis in AP. We found that Ripk3−/− mice had significantly more severe pancreatic edema and inflammation associated with macrophage and neutrophil infiltration than control mice. Consistently, Mlkl−/− mice were more susceptible to caerulein-induced AP, which occurred in a time- and dose-dependent manner, than control mice. Mlkl−/− mice exhibit weight loss, edematous pancreatitis, necrotizing pancreatitis, and acinar cell dedifferentiation in response to tissue damage. Genetic deletion of Mlkl resulted in downregulation of the antiapoptotic genes Bclxl and Cflar in association with increases in the numbers of apoptotic cells, as detected by TUNEL assay. These findings suggest that RIPK3 and MLKL-mediated necroptosis exerts protective effects in AP and caution against the use of necroptosis inhibitors for AP treatment.

Hippo Signaling Pathway in Pancreas Development.

The Hippo signaling pathway is a vital regulator of pancreatic development and homeostasis, directing cell fate decisions, morphogenesis, and adult pancreatic cellular plasticity. Through loss-of-function research, Hippo signaling has been found to play key roles in maintaining the proper balance between progenitor cell renewal, proliferation, and differentiation in pancreatic organogenesis. Other studies suggest that overactivation of YAP, a downstream effector of the pathway, promotes ductal cell development and suppresses endocrine cell fate specification via repression of Ngn3. After birth, disruptions in Hippo signaling have been found to lead to de-differentiation of acinar cells and pancreatitis-like phenotype. Further, Hippo signaling directs pancreatic morphogenesis by ensuring proper cell polarization and branching. Despite these findings, the mechanisms through which Hippo governs cell differentiation and pancreatic architecture are yet to be fully understood. Here, we review recent studies of Hippo functions in pancreatic development, including its crosstalk with NOTCH, WNT/β-catenin, and PI3K/Akt/mTOR signaling pathways.

MECOM permits pancreatic acinar cell dedifferentiation avoiding cell death under stress conditions

Maintenance of the pancreatic acinar cell phenotype suppresses tumor formation. Hence, repetitive acute or chronic pancreatitis, stress conditions in which the acinar cells dedifferentiate, predispose for cancer formation in the pancreas. Dedifferentiated acinar cells acquire a large panel of duct cell-specific markers. However, it remains unclear to what extent dedifferentiated acini differ from native duct cells and which genes are uniquely regulating acinar cell dedifferentiation. Moreover, most studies have been performed on mice since the availability of human cells is scarce. Here, we applied a non-genetic lineage tracing method of human pancreatic exocrine acinar and duct cells that allowed cell-type-specific gene expression profiling by RNA sequencing. Subsequent to this discovery analysis, one transcription factor that was unique for dedifferentiated acinar cells was functionally characterized. RNA sequencing analysis showed that human dedifferentiated acinar cells expressed genes in “Pathways of cancer” with a prominence of MECOM (EVI-1), a transcription factor that was not expressed by duct cells. During mouse embryonic development, pre-acinar cells also transiently expressed MECOM and in the adult mouse pancreas, MECOM was re-expressed when mice were subjected to acute and chronic pancreatitis, conditions in which acinar cells dedifferentiate. In human cells and in mice, MECOM expression correlated with and was directly regulated by SOX9. Mouse acinar cells that, by genetic manipulation, lose the ability to upregulate MECOM showed impaired cell adhesion, more prominent acinar cell death, and suppressed acinar cell dedifferentiation by limited ERK signaling. In conclusion, we transcriptionally profiled the two major human pancreatic exocrine cell types, acinar and duct cells, during experimental stress conditions. We provide insights that in dedifferentiated acinar cells, cancer pathways are upregulated in which MECOM is a critical regulator that suppresses acinar cell death by permitting cellular dedifferentiation.

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.

Abstract A12: The establishment, maintenance, and maladaptive role of epigenetic memory in mediating pancreatic tumorigenesis

Abstract Cellular decision-making is highly dependent on cues present in the environment. As such, biologic systems have evolved efficient ways to respond to salient and often transient stimuli by encoding and transducing relevant extracellular information to chromatin. Additionally, accumulating evidence suggests that cells are capable of remembering previously experienced stimuli, allowing them to adjust their behaviors appropriately when confronted in the future with a similar or different stimulus. However, the ability of cells to respond to a transient stimulus and to encode a persistent record of that experience following its resolution has yet to be explored comprehensively in a preneoplastic context. Here we determine the lasting effect in the pancreas of an acinar-to-ductal metaplasia (ADM) event, to elucidate the impact of prior inflammation on tissue function and subsequent tumorigenesis. In a lineage-traced model of acinar cell dedifferentiation, we demonstrate that following ADM, histologically normal acinar cells exhibit broad gains in chromatin accessibility that persist well after exposure to the initial ADM-inducing stimulus. We show that the effect on chromatin is not reflected in the transcriptional state of acinar cells. Moreover, we employ extensive flow-cytometry based analysis of immune cell and niche acinar populations to show there is no long-term cell-extrinsic population, nor a significant expansion of either the Dclk1+ or Nk1r+ acinar populations. Finally, we employ single-cell RNA-seq analyses to define the alterations to epithelial cells and the associated microenvironment long after regeneration following an episode of pancreatitis. These data suggest that inflammation-exposed acinar cells are capable of establishing an altered, persistently accessible chromatin state that lasts long after the initial lineage destabilizing event. Currently we are defining if, following resolution of pancreatitis, activation of mutant Kras will be sufficient to induce premalignant transformation within the acinar compartment that manifests as pancreatic intraepithelial neoplasia (PanIN)—the most common precursor lesion to pancreatic ductal adenocarcinoma (PDAC). Understanding how this postinflammatory chromatin state synergizes with oncogenic stress will further explain why inflammation is a hallmark risk factor for cancer development. Together, our studies will characterize the establishment, maintenance, and maladaptive role of epigenetic memory in the development of pancreatic cancer. Citation Format: David J. Falvo, Rohit Chandwani. The establishment, maintenance, and maladaptive role of epigenetic memory in mediating pancreatic tumorigenesis [abstract]. In: Proceedings of the AACR Special Conference on Pancreatic Cancer: Advances in Science and Clinical Care; 2019 Sept 6-9; Boston, MA. Philadelphia (PA): AACR; Cancer Res 2019;79(24 Suppl):Abstract nr A12.

Ring1b-dependent epigenetic remodelling is an essential prerequisite for pancreatic carcinogenesis

Background and aimsBesides well-defined genetic alterations, the dedifferentiation of mature acinar cells is an important prerequisite for pancreatic carcinogenesis. Acinar-specific genes controlling cell homeostasis are extensively downregulated during cancer development;...

Suppression of parotid acinar cell dysfunction by the free radical scavenger 3-methyl-1-phenyl-2-pyrazolin-5-one.

Salivary gland atrophy and consequent hyposalivation are serious problems in clinical dentistry, as saliva regulates the environment of the oral cavity. To clarify the mechanisms underlying salivary gland dysfunction, a system for primary culture of parotid acinar cells has been established. It has been reported previously that the process of cell isolation from parotid glands triggers stress signaling mediated by Src and p38 mitogen-activated protein (MAP) kinase (p38), leading to dedifferentiation of acinar cells, and that an nicotinamide adenine dinucleotide phosphate (NADPH) oxidase inhibitor suppresses this activation of Src and p38, suggesting that reactive oxygen species initiate the dedifferentiation signal. The present study examined the effect of a free radical scavenger, 3-methyl-1-phenyl-2-pyrazolin-5-one (also termed MCI-186 or edaravone), on activation of the stress signal and the secretory function of parotid acinar cells. Activation of p38 during cell isolation was suppressed by addition of MCI-186. The retention of the activity of amylase, a major salivary protein, and the number of amylase-containing secretory granules were improved by isolation and culture in the presence of MCI-186. In addition, calcium elevation upon stimulation with a muscarinic agonist was higher in MCI-186-treated cells than in untreated cells. These results suggest that MCI-186 (edaravone) is a promising agent for prevention of salivary gland dysfunction.

Enhanced proliferation of pancreatic acinar cells in MRL/MpJ mice is driven by severe acinar injury but independent of inflammation

Adult pancreatic acinar cells have the ability to re-enter the cell cycle and proliferate upon injury or tissue loss. Despite this mitotic ability, the extent of acinar proliferation is often limited and unable to completely regenerate the injured tissue or restore the initial volume of the organ, thus leading to pancreatic dysfunction. Identifying molecular determinants of enhanced proliferation is critical to overcome this issue. In this study, we discovered that Murphy Roths Large (MRL/MpJ) mice can be exploited to identify molecular effectors promoting acinar proliferation upon injury, with the ultimate goal to develop therapeutic regimens to boost pancreatic regeneration. Our results show that, upon cerulein-induced acinar injury, cell proliferation was enhanced and cell cycle components up-regulated in the pancreas of MRL/MpJ mice compared to the control strain C57BL/6. Initial damage of acinar cells was exacerbated in these mice, manifested by increased serum levels of pancreatic enzymes, intra-pancreatic trypsinogen activation and acinar cell apoptosis. In addition, MRL/MpJ pancreata presented enhanced inflammation, de-differentiation of acinar cells and acinar-to-ductal metaplasia. Manipulation of inflammatory levels and mitogenic stimulation with the thyroid hormone 5,3-L-tri-iodothyronine revealed that factors derived from initial acinar injury rather than inflammatory injury promote the replicative advantage in MRL/MpJ mice.

Malnutrition in Pancreatic Ductal Adenocarcinoma (PDA): Dietary Pancreatic Enzymes Improve Short-Term Health but Stimulate Tumor Growth

Pancreatic ductal adenocarcinoma (PDA) is a deadly cancer that resists efforts to identify better chemotherapeutics. PDA is associated with chronic pancreatitis and acinar cell dedifferentiation. This reduces enzyme production by the exocrine pancreas, resulting in digestive insufficiencies. Malabsorption of partially digested food causes bloating, overfilled intestines, abdominal pain, excessive feces, steatorrhea, and malnutrition. These maladies affect quality of life and restrict treatment options for pancreatitis and PDA. Here, we characterize health benefits and risks of dietary pancreatic enzymes in three mouse models of PDA-KC, KCR8-16, and KIC. KC expresses oncogenic KrasG12D in pancreatic tissue whereas KCR8-16 also has deletions of the Rgs8 and Rgs16 genes. Rgs proteins inhibit the release of digestive enzymes evoked by G-protein-coupled-receptor agonists. KC and KCR8-16 mice developed dedifferentiated exocrine pancreata within 2 months of age and became malnourished, underweight, hypoglycemic, and hypothermic. KC mice adapted but KCR8-16 mice rapidly transitioned to starvation after mild metabolic challenges. Dietary pancreatic enzyme supplements reversed these symptoms in KC and KCR8-16 animals, and extended survival. Therefore, we tested the benefits of pancreatic enzymes in an aggressive mouse model of PDA (KIC). Median survival improved with dietary pancreatic enzyme supplements and was extended further when combined with warfarin and gemcitabine chemotherapy. However, dietary pancreatic enzymes stimulated tumor growth in the terminal stages of disease progression in KIC mice.

Abstract B15: Defining functional PDAC-suppressive mechanisms of the acinar differentiation factor PTF1A

Abstract The primary goal of this study is to define the cell-intrinsic and cell-extrinsic mechanisms that lead to PDAC initiation in the absence of the acinar differentiation determinant PTF1A. PDAC development is a dynamic process that involves both alterations within the pancreatic epithelium and crosstalk with immune cells. Our lab and others have demonstrated that PanINs and PDAC arise through KRASG12D-mediated dedifferentiation and transformation of mature acinar cells, despite the cancer’s duct-like phenotype. Acinar-to-PanIN transformation, while typically inefficient, is greatly accelerated by caerulein-induced pancreatitis, highlighting the synergy between cell-intrinsic alterations, such as KRAS mutation, and cell-extrinsic influences, including inflammation. Recently, we identified another cell-intrinsic change that greatly hastens PanIN development: loss of acinar cell identity, via downregulation or deletion of the master acinar transcription factor, PTF1A. Since loss of differentiation has consequences both within the acinar cell and on the surrounding microenvironment, we want to understand what cell-autonomous and non-cell autonomous changes drive PDAC initiation following Ptf1a deletion. In this study we address two major questions: first, does SOX9 mediate acinar-to-ductal reprogramming (ADR) within acinar cells following Ptf1a deletion? And second, does Ptf1a deletion alter immune cell infiltration to influence tumorigenesis? Deletion of Ptf1a alone causes ADR and robust upregulation of the lineage-restricted ductal transcription factor SOX9. As previous studies have shown a requirement for the Sox9 gene in PanIN formation, we hypothesized that SOX9 is required to reprogram acinar cells to a tumor-susceptible state upon loss of PTF1A. In order to test this hypothesis, we have generated inducible, acinar specific, Ptf1a/Sox9 double knock-out mice. We are currently using these mice to determine the regulatory relationship between these key transcription factors in ADR and PanIN development, and we will present our preliminary findings at this meeting. Our recently published work additionally suggests that deletion of Ptf1a leads to numerous changes outside of the acinar cells themselves, including upregulation of fibro-inflammatory pathways associated with PDAC. These data suggest that acinar-intrinsic changes influence the stromal microenvironment, and lead us to hypothesize that acinar cell differentiation is a critical determinant of how Kras-mutant cells activate and respond to the immune system during tumor initiation. To begin to test this hypothesis, we characterized the immune cell infiltrate in pancreata from KrasG12D mice in which tumor initiation was stimulated either by caerulein-induced pancreatitis (KRAS/caerulein mice) or Ptf1a deletion (KRAS/cKO mice). While pancreata of both groups had abundant macrophage infiltration, we found that T-cell infiltration was more pronounced in KRAS/cKO mice than KRAS/caerulein mice. These data suggest that dedifferentiation has a non-cell-autonomous effect on the response of the immune system to Kras-mutant precancerous cells. We next wanted to test whether dedifferentiation changed the response of the precancerous microenvironment to anti-inflammatory agents such as dexamethasone (DEX), which has been previously shown to inhibit PanIN formation. Consistent with previous results, we found that DEX alleviated PanIN formation and preserved histologically normal acinar tissue in KRAS/caerulein mice, which retain wild-type PTF1A. Paradoxically, however, DEX treatment enhanced PanIN formation in KRAS/cKO mice, indicating that PTF1A-mediated differentiation pathways are required for the anti-tumor effects of this commonly-used drug. In ongoing studies, we will use these genetic and pharmacological tools to determine what inflammatory cells and signals are required for ADR and subsequent PanIN initiation. Citation Format: Nathan M. Krah, Shuba M. Narayanan, Deanne E. Yugawa, L Charles Murtaugh.{Authors}. Defining functional PDAC-suppressive mechanisms of the acinar differentiation factor PTF1A. [abstract]. In: Proceedings of the AACR Special Conference on Pancreatic Cancer: Advances in Science and Clinical Care; 2016 May 12-15; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2016;76(24 Suppl):Abstract nr B15.

Abstract A59: Crosstalk of different macrophage populations with pancreatic acinar or PanIN cells and contribution to development of pancreatic cancer

Abstract Pancreatic cancer is characterized by an inflammatory environment. Here we delineate the crosstalk between different macrophage populations with pancreatic cells carrying oncogenic Kras mutations. First, we show that pancreatic acinar cells that undergo oncogenic transformation by mutant Kras upregulate chemoattractants that attract inflammatory macrophages. These inflammatory macrophages contribute to acinar cell dedifferentiation to a progenitor-like cell type (acinar-to-ductal metaplasia; ADM). Resulting cells can give rise to PanIN lesions. We then provide insight at which stage of PanIN formation a switch between inflammatory and alternatively-activated macrophages occurs; and define one mechanism by which this can be mediated. Eventually, we provide insight of how alternatively-activated macrophages facilitate the further progression of PanIN lesions to a more aggressive phenotype. Citation Format: Geou-Yarh Liou, Heike Doeppler, Ligia Bastea, Peter Storz.{Authors}. Crosstalk of different macrophage populations with pancreatic acinar or PanIN cells and contribution to development of pancreatic cancer. [abstract]. In: Proceedings of the AACR Special Conference on Pancreatic Cancer: Advances in Science and Clinical Care; 2016 May 12-15; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2016;76(24 Suppl):Abstract nr A59.

Quantitative ultrasound and the pancreas

Pancreatitis is inflammation of the pancreas. Cerulein-induced pancreatitis in animal models can cause a significant increase in pancreatic enzymes in blood, as well as interstitial edema and inflammatory cell infiltration in the pancreas. This degree of pancreatitis is mild; all animals survive the induction of pancreatitis and resolves within ~6 days after induction, making this an excellent model to study the attenuation coefficient (AC: dB/cm-MHz) and backscatter coefficient (BSC: 1/cm-sr) of the pancreas temporally. The edematous stroma and shrinkage and dedifferentiation of acinar cells, has certain similarities with the morphology in some forms of pancreatic carcinoma. The pancreas’ AC and BSC (20-50 MHz) were estimated in vivo and ex vivo at baseline (before cerulein injections) and at 24 h, 48 h and 72 h after cerulein injections in Sprague-Dawley rats (N = 24). AC and BSC showed the same trends whereby (relative to baseline values) the 24-h AC decreased ~0.3 dB/cm-MHz and BSC decreased ~1-2 dB w...

The analgesic effect of the mitochondria targeted antioxidant SkQ in experimental pancreatitis

s / Pancreatology 16 (2016) S1eS130 S14 pancreas. In addition, lack of Akt1 resulted in reduced acinar cell proliferation and de-differentiation into acinar-to-ductal metaplasia. Molecular analyses revealed a down-regulation of TGF-b signaling in Akt1-/mice. Conclusion: Our results revealed that Akt1 signaling does not mediate the initial acinar cell damage observed at the onset of AP. However, Akt1 signaling promotes both the inflammatory response and the regeneration of the pancreatic tissue. These findings provide novel insights into the molecular pathways governing pancreatic inflammation and tissue regeneration, with potential therapeutic implications.

Mutant KRas-Induced Mitochondrial Oxidative Stress in Acinar Cells Upregulates EGFR Signaling to Drive Formation of Pancreatic Precancerous Lesions.

The development of pancreatic cancer requires the acquisition of oncogenic KRas mutations and upregulation of growth factor signaling, but the relationship between these is not well established. Here, we show that mutant KRas alters mitochondrial metabolism in pancreatic acinar cells, resulting in increased generation of mitochondrial reactive oxygen species (mROS). Mitochondrial ROS then drives the dedifferentiation of acinar cells to a duct-like progenitor phenotype and progression to PanIN. This is mediated via the ROS-receptive kinase protein kinase D1 and the transcription factors NF-κB1 and NF-κB2, which upregulate expression of the epidermal growth factor, its ligands, and their sheddase ADAM17. In vivo, interception of KRas-mediated generation of mROS reduced the formation of pre-neoplastic lesions. Hence, our data provide insight into how oncogenic KRas interacts with growth factor signaling to induce the formation of pancreatic cancer.

Role of bile acids in carcinogenesis of pancreatic cancer: An old topic with new perspective.

The role of bile acids in colorectal cancer has been well documented, but their role in pancreatic cancer remains unclear. In this review, we examined the risk factors of pancreatic cancer. We found that bile acids are associated with most of these factors. Alcohol intake, smoking, and a high-fat diet all lead to high secretion of bile acids, and bile acid metabolic dysfunction is a causal factor of gallstones. An increase in secretion of bile acids, in addition to a long common channel, may result in bile acid reflux into the pancreatic duct and to the epithelial cells or acinar cells, from which pancreatic adenocarcinoma is derived. The final pathophysiological process is pancreatitis, which promotes dedifferentiation of acinar cells into progenitor duct-like cells. Interestingly, bile acids act as regulatory molecules in metabolism, affecting adipose tissue distribution, insulin sensitivity and triglyceride metabolism. As a result, bile acids are associated with three risk factors of pancreatic cancer: obesity, diabetes and hypertriglyceridemia. In the second part of this review, we summarize several studies showing that bile acids act as cancer promoters in gastrointestinal cancer. However, more question are raised than have been solved, and further oncological and physiological experiments are needed to confirm the role of bile acids in pancreatic cancer carcinogenesis.

Identification of miRNAs Involved in Reprogramming Acinar Cells into Insulin Producing Cells.

Reprogramming acinar cells into insulin producing cells using adenoviral (Ad)-mediated delivery of Pdx1, Ngn3 and MafA (PNM) is an innovative approach for the treatment of diabetes. Here, we aimed to investigate the molecular mechanisms involved in this process and in particular, the role of microRNAs. To this end, we performed a comparative study of acinar-to-β cell reprogramming efficiency in the rat acinar cell line AR42J and its subclone B13 after transduction with Ad-PNM. B13 cells were more efficiently reprogrammed than AR42J cells, which was demonstrated by a strong activation of β cell markers (Ins1, Ins2, IAPP, NeuroD1 and Pax4). miRNome panels were used to analyze differentially expressed miRNAs in acinar cells under four experimental conditions (i) non-transduced AR42J cells, (ii) non-transduced B13 cells, (iii) B13 cells transduced with Ad-GFP vectors and (iv) B13 cells transduced with Ad-PNM vectors. A total of 59 miRNAs were found to be differentially expressed between non-transduced AR42J and B13 cells. Specifically, the miR-200 family was completely repressed in B13 cells, suggesting that these cells exist in a less differentiated state than AR42J cells and as a consequence they present a greater plasticity. Adenoviral transduction per se induced dedifferentiation of acinar cells and 11 miRNAs were putatively involved in this process, whereas 8 miRNAs were found to be associated with PNM expression. Of note, Ad-PNM reprogrammed B13 cells presented the same levels of miR-137-3p, miR-135a-5p, miR-204-5p and miR-210-3p of those detected in islets, highlighting their role in the process. In conclusion, this study led to the identification of miRNAs that might be of compelling importance to improve acinar-to-β cell conversion for the future treatment of diabetes.