Deficient Endoplasmic Reticulum Acetyl-CoA Import in Pancreatic Acinar Cells Leads to Chronic Pancreatitis

BACKGROUND & AIMS

Maintaining endoplasmic reticulum (ER) proteostasis is essential for pancreatic acinar cell function. Under conditions of severe ER stress, activation of pathogenic unfolded protein response pathways plays a central role in the development and progression of pancreatitis. Less is known, however, of the consequence of perturbing ER-associated post-translational protein modifications on pancreatic outcomes. Here, we examined the role of the ER acetyl-CoA transporter AT-1 on pancreatic homeostasis.

METHODS

We used an AT-1S113R/+ hypomorphic mouse model, and generated an inducible, acinar-specific, AT-1 knockout mouse model, and performed histologic and biochemical analyses to probe the effect of AT-1 loss on acinar cell physiology.

RESULTS

We found that AT-1 expression is down-regulated significantly during both acute and chronic pancreatitis. Furthermore, acinar-specific deletion of AT-1 in acinar cells induces chronic ER stress marked by activation of both the spliced x-box binding protein 1 and protein kinase R-like ER kinase pathways, leading to spontaneous mild/moderate chronic pancreatitis evidenced by accumulation of intracellular trypsin, immune cell infiltration, and fibrosis. Induction of acute-on-chronic pancreatitis in the AT-1 model led to acinar cell loss and glad atrophy.

CONCLUSIONS

These results indicate a key role for AT-1 in pancreatic acinar cell homeostasis, the unfolded protein response, and that perturbations in AT-1 function leads to pancreatic disease.

Pancreas-specific deletion of protein kinase D attenuates inflammation, necrosis, and severity of acute pancreatitis

BACKGROUND

Protein kinase D (PKD) family, which includes PKD/PKD1, PKD2, and PKD3, has been increasingly implicated in the regulation of multiple cellular functions and human diseases. We recently reported that pharmacologic inhibition of PKD ameliorated the pathologic responses and severity of pancreatitis. However, to further investigate the importance of PKD family members in pancreatitis, it is necessary to explore the effects of pancreas-specific genetic inhibition of PKD isoform on pathology of pancreatitis.

METHODS

We generated a mouse model (referred as PKD3Δpanc mice) with pancreas-specific deletion of PKD3, the predominant PKD isoform in mouse pancreatic acinar cells, by crossing Pkd3flox/flox mice with Pdx1-Cre transgenic mice which express Cre recombinase under the control of the mouse Pdx1 promoter. Pancreas-specific deletion of the PKD3 gene and PKD3 protein was confirmed by PCR and Western blot analysis. Experimental pancreatitis was induced in PKD3Δpanc and Pkd3flox/flox (control mice) littermates by intraperitoneal injections of cerulein or L-arginine.

RESULTS

Compared to the control mice, PKD3Δpanc mice displayed significant attenuation in inflammation, necrosis, and severity of pancreatitis in both experimental models. PKD3Δpanc mice had markedly decreased NF-κB and trypsinogen activation, pancreatic mRNA expression of multiple inflammatory molecules, and the receptor-interacting protein kinase 1 (RIP1) activation in pancreatitis. PKD3Δpanc mice also had less pancreatic ATP depletion, increased pro-survival Bcl-2 family protein expression, and autophagy promotion.

CONCLUSION

With PKD3Δpanc mouse model, we further demonstrated that PKD plays a critical role in pathobiological process of pancreatitis and PKD constitutes a novel therapeutic target to treat this disorder.

Trypsin activity governs increased susceptibility to pancreatitis in mice expressing human PRSS1R122H

Currently, an effective targeted therapy for pancreatitis is lacking. Hereditary pancreatitis (HP) is a heritable, autosomal-dominant disorder with recurrent acute pancreatitis (AP) progressing to chronic pancreatitis (CP) and a markedly increased risk of pancreatic cancer. In 1996, mutations in PRSS1 were linked to the development of HP. Here, we developed a mouse model by inserting a full-length human PRSS1R122H gene, the most commonly mutated gene in human HP, into mice. Expression of PRSS1R122H protein in the pancreas markedly increased stress signaling pathways and exacerbated AP. After the attack of AP, all PRSS1R122H mice had disease progression to CP, with similar histologic features as those observed in human HP. By comparing PRSS1R122H mice with PRSS1WT mice, as well as enzymatically inactivated Dead-PRSS1R122H mice, we unraveled that increased trypsin activity is the mechanism for R122H mutation to sensitize mice to the development of pancreatitis. We further discovered that trypsin inhibition, in combination with anticoagulation therapy, synergistically prevented progression to CP in PRSS1R122H mice. These animal models help us better understand the complex nature of this disease and provide powerful tools for developing and testing novel therapeutics for human pancreatitis.

Exocrine Pancreatic Dysfunction Increases the Risk of New-Onset Diabetes Mellitus: Results of a Nationwide Cohort Study

It is well established that individuals with diabetes mellitus (DM) may develop exocrine pancreatic dysfunction (EPD) requiring pancreatic enzyme replacement therapy, whereas the converse relationship has been poorly studied. Pancreatitis is a disease that is well suited to investigate the latter as it is often characterized by the development of EPD and/or new‐onset DM. The aim was to investigate the association between EPD and the risk of new‐onset DM in individuals after the first attack of pancreatitis. Using nationwide pharmaceutical dispensing data and hospital discharge data, this cohort study included a total of 9,124 post‐pancreatitis individuals. EPD was defined as having two or more dispensing records of pancreatic enzymes. Considering EPD as a time‐dependent variable, multivariable Cox regression analysis was conducted. A 1‐year lag period between EPD and DM was introduced to minimize reverse causality. Age, sex, ethnicity, alcohol consumption, tobacco smoking, social deprivation index, Charlson comorbidity index, and use of proton pump inhibitors were adjusted for. In the overall cohort, EPD was associated with a significantly higher risk for new‐onset DM (adjusted hazard ratio, 3.83; 95% confidence interval, 2.37–6.18). The association remained statistically significant when a 1‐year lag period was applied (adjusted hazard ratio, 2.51; 95% confidence interval, 1.38–4.58), as well as when the analysis was constrained to mild acute pancreatitis (4.65; 2.18–9.93). The findings suggest that individuals with EPD, even those without extensive mechanistic destruction of the pancreas, are at an increased risk for new‐onset DM. Purposely designed studies are warranted to investigate mechanisms behind the association and if the mechanisms could be targeted therapeutically.

Dual targeting of GSK3B and HDACs reduces tumor growth and improves survival in an ovarian cancer mouse model

Objective.

To investigate the anti-tumor effect of a newly-developed dual inhibitor (APCS-540) of glycogen synthase kinase 3 beta (GSK3B) and histone deacetylases (HDACs) in ovarian cancer cells.

Methods.

The effects of APCS-540 on cancer cell proliferation, migration, invasion and cancer stemness were investigated in vitro in human (KURAMOCHI, OVCA420, OVSAHO) and mouse (BR-Luc, ID8, MOSE-HRas-Myc) ovarian cancer cells. Cisplatin-sensitive (A2780) and cisplatin-resistant (A2780cis) cell lines were used to evaluate APCS-540’s effect on chemoresistance. The immunocompetent syngeneic mouse model BR-Luc was used to test the effect of APCS-540 on ovarian cancer progression and survival.

Results.

APCS-540 showed significant anti-tumor effects in vitro in both human and mouse ovarian cancer cells. Importantly, APCS-540 demonstrated marked cytotoxicity against cisplatin-resistant cancer cells and reversed cisplatin-resistance when used in combination with platinum. APCS-540 significantly decreased cancer cell invasion. A significant 66% increase in survival was observed in mice treated with APCS-540 compared to control mice.

Conclusion.

Dual inhibition of GSK3B and HDACs via APCS-540 showed potent anti-tumor activity in vitro and in vivo, suggesting that APCS-540 may provide a novel treatment option for ovarian cancer, including the platinum-resistant disease.

New-Onset Diabetes, Longitudinal Trends in Metabolic Markers, and Risk of Pancreatic Cancer in a Heterogeneous Population

BACKGROUND & AIMS

Observational studies of predominantly white populations have found new-onset diabetes to be associated with increased risk of pancreatic cancer. We sought to determine whether this relationship applies to other races or ethnicities and to identify metabolic profiles associated with increased risk of pancreatic cancer.

METHODS

We conducted a population-based cohort study of Asian, black, Hispanic and white patients from Kaiser Permanente Southern California from 2006 through 2016 (n = 1,499,627). Patients with diabetes were identified based on glucose and hemoglobin A1c (HbA1c) measurements. We used Cox regression to assess the relationship between diabetes status and duration and pancreatic cancer. For patients with recent diagnoses of diabetes (1 year or less) we compared longitudinal changes in glucose, HbA1c, and weight, from time of diabetes diagnosis through 3 years prior to the diagnosis, in patients with vs without pancreatic cancer.

RESULTS

We identified 2,002 incident cases of pancreatic cancer from nearly 7.5 million person-years of follow-up. Compared to patients without diabetes, individuals who received a recent diagnosis of diabetes had an almost 7-fold increase in risk of pancreatic cancer (relative risk, 6.91; 95% CI, 5.76-8.30). Among patients with a recent diagnosis of diabetes, those who developed pancreatic cancer had more rapid increases in levels of glucose (Δslope: cases, 37.47 mg/dL vs non-cases, 27.68 mg/dL) and HbA1c (Δslope: cases, 1.39% vs non-cases, 0.86%) in the month preceding the diagnosis of diabetes, and subtle weight loss in the prior years (slope: cases -0.18 kg/interval vs non-cases 0.33 kg/interval). These longitudinal changes in markers of metabolism were stronger for specific race and ethnic groups.

CONCLUSIONS

In a study of a large ethnically diverse population, we found risk of pancreatic cancer to be increased among patients with a diagnosis of diabetes in the past year among different races and ethnicities. Weight loss and rapid development of poor glycemic control were associated with increased risk of pancreatic cancer in multiple races.

Early detection of pancreatic cancer

Pancreatic ductal adenocarcinoma is most frequently detected at an advanced stage. Such late detection restricts treatment options and contributes to a dismal 5-year survival rate of 3-15%. Pancreatic ductal adenocarcinoma is relatively uncommon and screening of the asymptomatic adult population is not feasible or recommended with current modalities. However, screening of individuals in high-risk groups is recommended. Here, we review groups at high risk for pancreatic ductal adenocarcinoma, including individuals with inherited predisposition and patients with pancreatic cystic lesions. We discuss studies aimed at finding ways of identifying pancreatic ductal adenocarcinoma in high-risk groups, such as among individuals with new-onset diabetes mellitus and people attending primary and secondary care practices with symptoms that suggest this cancer. We review early detection biomarkers, explore the potential of using social media for detection, appraise prediction models developed using electronic health records and research data, and examine the application of artificial intelligence to medical imaging for the purposes of early detection.

Targeting the CBP/β-Catenin Interaction to Suppress Activation of Cancer-Promoting Pancreatic Stellate Cells

Background: Although cyclic AMP-response element binding protein-binding protein (CBP)/β-catenin signaling is known to promote proliferation and fibrosis in various organ systems, its role in the activation of pancreatic stellate cells (PSCs), the key effector cells of desmoplasia in pancreatic cancer and fibrosis in chronic pancreatitis, is largely unknown. Methods: To investigate the role of the CBP/β-catenin signaling pathway in the activation of PSCs, we have treated mouse and human PSCs with the small molecule specific CBP/β-catenin antagonist ICG-001 and examined the effects of treatment on parameters of activation. Results: We report for the first time that CBP/β-catenin antagonism suppresses activation of PSCs as evidenced by their decreased proliferation, down-regulation of “activation” markers, e.g., α-smooth muscle actin (α-SMA/Acta2), collagen type I alpha 1 (Col1a1), Prolyl 4-hydroxylase, and Survivin, up-regulation of peroxisome proliferator activated receptor gamma (Ppar-γ) which is associated with quiescence, and reduced migration; additionally, CBP/β-catenin antagonism also suppresses PSC-induced migration of cancer cells. Conclusion: CBP/β-catenin antagonism represents a novel therapeutic strategy for suppressing PSC activation and may be effective at countering PSC promotion of pancreatic cancer.

Abstract C071: Racial/ethnic disparities in weight, weight change in adulthood, and pancreatic cancer incidence: The Multiethnic Cohort

Purpose: Japanese Americans, Native Hawaiians and African Americans have a higher incidence of pancreatic cancer compared to non-Hispanic whites that cannot be explained by the rates of obesity or absolute body weight. While absolute body weight in adulthood is positively associated with pancreatic cancer risk, the effect of weight change throughout adulthood, particularly among a racially diverse population, is not well documented for this high-risk group. Methods: This population-based prospective cohort study included 155,308 participants enrolled in the Multiethnic Cohort from 1993-1996 (median follow-up = 20.2 years). We identified 1,328 participants diagnosed with incident primary invasive pancreatic cancer from the linked cohort data with the Hawaii and California SEER registries. Participants diagnosed with other cancers were excluded from the cohort analysis. Body weight at 21 years old and at baseline enrollment (age 45 or older) were assessed using a self-administered questionnaire at cohort entry. Multivariable Cox proportional hazards regression models were used to determine the association between weight change from age 21 to cohort entry and pancreatic cancer risk adjusting for known risk factors such as smoking status, physical activity, alcohol intake, family history of pancreatic cancer and other sociodemographic characteristics. Results: The mean age at cohort entry was 59.3 years (SD 8.9) and the largest proportion of the cohort were Japanese American (30.1%), White (25.0%), and Latino (21.8%), respectively. The mean weight change from age 21 to baseline age was 28 pounds (SD 26.7). We observed that increased risk of pancreatic cancer was associated with weight at age 21 (HR 1.06; 95% CI 1.03-1.09, per 10-pound increase; p-trend<0.001) and weight at baseline (1.03; 1.00-1.05, per 10-pound increase; p-tend=0.03). Weight gain through adulthood (per pound increase per year) was associated with 11% increased risk of pancreatic cancer (1.11; 1.03-1.20) after adjusting for known lifestyle and behavioral risk factors. There was a significant interaction (p=0.03) between weight gain per year in adulthood and race/ethnicity, where Japanese Americans and Latinos experienced a 36% (1.36; 95% CI 1.14-1.64; p-trend<0.001) and 33% (1.33; 95% CI 1.11-1.59; p-trend=0.02) increased risk of pancreatic cancer per pound gained per year, respectively. Conclusion: Our findings indicate that weight gain in adulthood has a significant and independent impact on pancreatic cancer risk and specifically among racial/ethnic minorities. This study underscores the importance of maintaining a stable weight through adulthood, regardless of weight at age 21, in order to lower the risk of pancreatic cancer.

Citation Format: Albert J Farias, Daniel O Stram, Songren Wang, Stephen J Pandol, Kristine R Monroe, V. Wendy Setiawan. Racial/ethnic disparities in weight, weight change in adulthood, and pancreatic cancer incidence: The Multiethnic Cohort [abstract]. In: Proceedings of the Twelfth AACR Conference on the Science of Cancer Health Disparities in Racial/Ethnic Minorities and the Medically Underserved; 2019 Sep 20-23; San Francisco, CA. Philadelphia (PA): AACR; Cancer Epidemiol Biomarkers Prev 2020;29(6 Suppl_2):Abstract nr C071.

TRPV4 channel opening mediates pressure-induced pancreatitis initiated by Piezo1 activation

Elevated pressure in the pancreatic gland is the central cause of pancreatitis following abdominal trauma, surgery, endoscopic retrograde cholangiopancreatography, and gallstones. In the pancreas, excessive intracellular calcium causes mitochondrial dysfunction, premature zymogen activation, and necrosis, ultimately leading to pancreatitis. Although stimulation of the mechanically activated, calcium-permeable ion channel Piezo1 in the pancreatic acinar cell is the initial step in pressure-induced pancreatitis, activation of Piezo1 produces only transient elevation in intracellular calcium that is insufficient to cause pancreatitis. Therefore, how pressure produces a prolonged calcium elevation necessary to induce pancreatitis is unknown. We demonstrate that Piezo1 activation in pancreatic acinar cells caused a prolonged elevation in intracellular calcium levels, mitochondrial depolarization, intracellular trypsin activation, and cell death. Notably, these effects were dependent on the degree and duration of force applied to the cell. Low or transient force was insufficient to activate these pathological changes, whereas higher and prolonged application of force triggered sustained elevation in intracellular calcium, leading to enzyme activation and cell death. All of these pathological events were rescued in acinar cells treated with a Piezo1 antagonist and in acinar cells from mice with genetic deletion of Piezo1. We discovered that Piezo1 stimulation triggered transient receptor potential vanilloid subfamily 4 (TRPV4) channel opening, which was responsible for the sustained elevation in intracellular calcium that caused intracellular organelle dysfunction. Moreover, TRPV4 gene-KO mice were protected from Piezo1 agonist- and pressure-induced pancreatitis. These studies unveil a calcium signaling pathway in which a Piezo1-induced TRPV4 channel opening causes pancreatitis.

Recent Advances in Understanding the Complexity of Alcohol-Induced Pancreatic Dysfunction and Pancreatitis Development

Chronic excessive alcohol use is a well-recognized risk factor for pancreatic dysfunction and pancreatitis development. Evidence from in vivo and in vitro studies indicates that the detrimental effects of alcohol on the pancreas are from the direct toxic effects of metabolites and byproducts of ethanol metabolism such as reactive oxygen species. Pancreatic dysfunction and pancreatitis development are now increasingly thought to be multifactorial conditions, where alcohol, genetics, lifestyle, and infectious agents may determine the initiation and course of the disease. In this review, we first highlight the role of nonoxidative ethanol metabolism in the generation and accumulation of fatty acid ethyl esters (FAEEs) that cause multi-organellar dysfunction in the pancreas which ultimately leads to pancreatitis development. Further, we discuss how alcohol-mediated altered autophagy leads to the development of pancreatitis. We also provide insights into how alcohol interactions with other co-morbidities such as smoking or viral infections may negatively affect exocrine and endocrine pancreatic function. Finally, we present potential strategies to ameliorate organellar dysfunction which could attenuate pancreatic dysfunction and pancreatitis severity.

Antiviral Effects of Menthol on Coxsackievirus B

Coxsackievirus B (CVB) is a common human enterovirus that causes systemic infection but specifically replicates to high titers in the pancreas. It was reported that certain viruses induce mitochondrial fission to support infection. We documented that CVB triggers mitochondrial fission and blocking mitochondrial fission limits infection. The transient receptor potential channels have been implicated in regulating mitochondrial dynamics; namely, the heat and capsaicin receptor transient receptor potential cation channel subfamily V member 1 (TRPV1) contributes to mitochondrial depolarization and fission. When we transiently warmed HeLa cells to 39 °C prior to CVB exposure, infection was heightened, whereas cooling cells to 25 °C reduced infection. Inducing "cold" by stimulating transient receptor potential cation channel subfamily M member 8 (TRPM8) with menthol led to reduced infection and also resulted in lower levels of mitochondrial fission during infection. Additionally, menthol stabilized levels of mitochondrial antiviral signaling (MAVS) which is known to be tied to mitochondrial dynamics. Taken together, this highlights a novel pathway wherein CVB relies on TRPV1 to initiate proviral mitochondrial fission, which may contribute to the disruption of antiviral immunity. TRPM8 has been shown to antagonize TRPV1, and thus we hypothesize that stimulating TRPM8 blocks TRPV1-mediated mitochondrial fragmentation following CVB exposure and attenuates infection.

Vitamin D signaling maintains intestinal innate immunity and gut microbiota: potential intervention for metabolic syndrome and NAFLD

A lack of sunlight exposure, residence in the northern latitudes, and dietary vitamin D insufficiency are coprevalent with metabolic syndrome (MetS), Type 2 diabetes (T2D), and nonalcoholic fatty liver diseases (NAFLD), implying a potential causality and underlying mechanism. Whether vitamin D supplementation or treatment can improve these disorders is controversial, in part, because of the absence of large-scale trials. Experimental investigations, on the other hand, have uncovered novel biological functions of vitamin D in development, tumor suppression, and immune regulation, far beyond its original role as a vitamin that maintained calcium homeostasis. While the large intestine harbors massive numbers of microbes, the small intestine has a minimal quantity of bacteria, indicating the existence of a gating system located in the distal region of the small intestine that may restrain bacterial translocation to the small intestine. Vitamin D receptor (VDR) was found to be highly expressed at the distal region of small intestine, where the vitamin D signaling promotes innate immunity, including the expression of α-defensins by Paneth cells, and maintains the intestinal tight junctions. Thus, a new hypothesis is emerging, indicating that vitamin D deficiency may impair the intestinal innate immunity, including downregulation of Paneth cell defensins, leading to bacterial translocation, endotoxemia, systemic inflammation, insulin resistance, and hepatic steatosis. Here, we review the studies for vitamin D for innate immunity and metabolic homeostasis, and we outline the clinical trials of vitamin D for mitigating MetS, T2D, and NAFLD.

Multiparametric Mapping Magnetic Resonance Imaging of Pancreatic Disease

Background

Current magnetic resonance imaging (MRI) of pancreatic disease is qualitative in nature. Quantitative imaging offers several advantages, including increased reproducibility and sensitivity to detect mild or diffuse disease. The role of multiparametric mapping MRI in characterizing various tissue types in pancreatic disease such as chronic pancreatitis (CP) and pancreatic ductal adenocarcinoma (PDAC) has rarely been evaluated.

Purpose

To evaluate the feasibility of multiparametric mapping [T1, T2, and apparent diffusion coefficient (ADC)] in defining tissue characteristics that occur in CP and PDAC to improve disease diagnosis.

Materials and Methods:

Pancreatic MRI was performed in 17 patients with PDAC undergoing therapy, 7 patients with CP, and 29 healthy volunteers with no pancreatic disease. T1 modified Look-Locker Inversion Recovery (T1 MOLLI), T2-prepared gradient-echo, and multi-slice single-shot echo-planar diffusion weighted imaging (SS-EPI DWI) sequences were used for data acquisition. Regions of interest (ROIs) of pancreas in PDAC, CP, and control subjects were outlined by an experienced radiologist. One-way analysis of variance (ANOVA) was used to compare the difference between groups and regions of the pancreas, and Tukey tests were used for multiple comparison testing within groups. Receiver operator characteristic (ROC) curves were analyzed, and the areas under the curves (AUCs) were calculated using single parameter and combined parameters, respectively.

Results

T1, T2, and ADC values of the entire pancreas among PDAC, CP, and control subjects; and between upstream and downstream portions of the pancreas in PDAC patients were all significantly different (p < 0.05). The AUC values were 0.90 for T1, 0.55 for T2, and 0.71 for ADC for independent prediction of PDAC. By combining T1, T2, and ADC, the AUC value was 0.94 (sensitivity 91.54%, specificity 85.81%, 95% CI: 0.92–0.96), which yielded higher accuracy than any one parameter only (p < 0.001).

Conclusion

Multiparametric mapping MRI is feasible for the evaluation of the differences between PDAC, CP, and normal pancreas tissues. The combination of multiple parameters of T1, T2, and ADC provides a higher accuracy than any single parameter alone in tissue characterization of the pancreas.

Cancer-stromal cell fusion as revealed by fluorescence protein tracking

PURPOSE

We previously determined that cancer-stromal interaction was a direct route to tumor cell heterogeneity progression, since cancer-stromal cell fusion in coculture resulted in the creation of heterogeneous clones of fusion hybrid progeny. In this report, we modified the cancer-stromal coculture system to establish optimal experimental conditions for investigating cell fusion machinery and the mechanism of heterogeneity progression.

EXPERIMENTAL DESIGN

Red fluorescence protein-tagged LNCaP cells were cocultured with green fluorescence protein-labeled prostate stromal cells for cancer-stromal cell fusion, which was tracked as dual fluorescent cells by fluorescence microscopy.

RESULTS

We identified the most efficient strategy to isolate clones of fusion hybrid progenies. From the coculture, mixed cells including fusion hybrids were subjected to low-density replating for colony formation by fusion hybrid progeny. These colonies could propagate into derivative cell populations. Compared to the parental LNCaP cells, clones of the fusion hybrid progeny displayed divergent behaviors and exhibited permanent genomic hybridization.

CONCLUSIONS

Cancer-stromal cell fusion leads to cancer cell heterogeneity. The cancer-stromal coculture system characterized in this study can be used as a model for molecular characterization of cancer cell fusion as the mechanism behind the progression of heterogeneity observed in clinical prostate cancers.

Cancer cell's neuroendocrine feature can be acquired through cell-cell fusion during cancer-neural stem cell interaction

Advanced and therapy-resistant prostate tumors often display neural or neuroendocrine behavior. We assessed the consequences of prostate cancer cell interaction with neural cells, which are rich in the human prostate and resident of the prostate tumor. In 3-dimensional co-culture with neurospheres, red fluorescent human LNCaP cells formed agglomerates on the neurosphere surface. Upon induced neural differentiation, some red fluorescent cells showed morphology of fully differentiated neural cells, indicating fusion between the cancer and neural stem cells. These fusion hybrids survived for extended times in a quiescent state. A few eventually restarted cell division and propagated to form derivative hybrid progenies. Clones of the hybrid progenies were highly heterogeneous; most had lost prostatic and epithelial markers while some had acquired neural marker expression. These results indicate that cancer cells can fuse with bystander neural cells in the tumor microenvironment; and cancer cell fusion is a direct route to tumor cell heterogeneity.

Pathogenic Carboxyl Ester Lipase (CEL) Variants Interact with the Normal CEL Protein in Pancreatic Cells

Mutations in the gene encoding the digestive enzyme carboxyl ester lipase (CEL) are linked to pancreatic disease. The CEL variant denoted CEL-HYB predisposes to chronic pancreatitis, whereas the CEL-MODY variant causes MODY8, an inherited disorder of endocrine and exocrine pancreatic dysfunction. Both pathogenic variants exhibit altered biochemical and cellular properties compared with the normal CEL protein (CEL-WT, wild type). We here aimed to investigate effects of CEL variants on pancreatic acinar and ductal cell lines. Following extracellular exposure, CEL-HYB, CEL-MODY, and CEL-WT were endocytosed. The two pathogenic CEL proteins significantly reduced cell viability compared with CEL-WT. We also found evidence of CEL uptake in primary human pancreatic acinar cells and in native ductal tissue. Moreover, coexpression of CEL-HYB or CEL-MODY with CEL-WT affected secretion of the latter, as CEL-WT was observed to accumulate intracellularly to a higher degree in the presence of either pathogenic variant. Notably, in coendocytosis experiments, both pathogenic variants displayed a modest effect on cell viability when CEL-WT was present, indicating that the normal protein might diminish toxic effects conferred by CEL-HYB and CEL-MODY. Taken together, our findings provide valuable insight into how the pathogenic CEL variants predispose to pancreatic disease and why these disorders develop slowly over time.

Yes-Associated Protein 1 Plays Major Roles in Pancreatic Stellate Cell Activation and Fibroinflammatory Responses

Background: Yes-associated protein 1 (YAP), a transcriptional co-activator and major effector of the Hippo pathway, regulates cell differentiation and morphology in many cell types and supports aberrant tumor growth. Recent studies showed that YAP is expressed in pancreas tissues in pancreatic ductal adenocarcinoma (PDAC) patients and experimental models of PDAC, with YAP largely found in cancer cells and pancreatic stellate cells (PaSC) in the stroma. Methods and Results: We studied here the role of YAP in the activated phenotype of PaSC. We found that YAP is expressed at low levels in normal mouse pancreas, but protein levels significantly increased after pancreas inflammatory damage induced by repeated cerulein administration in wild-type mice or upon initiation of neoplastic transformation of the pancreas parenchyma in Ptf1-Cre;LSL-KrasG12D/+ (KC) mice. In these animal models, YAP upregulation occurred in parallel with activation and proliferation of PaSC. Consistent with these findings, we found robust YAP expression in culture-activated mouse and human PaSC but not in quiescent, freshly isolated cells. Fully activated PaSC isolated from KC mice or PDAC patient tissues exhibited robust nuclear YAP suggesting YAP transcriptional activity. Agents that induce quiescence such as the Bromodomain and Extra-Terminal (BET) inhibitor iBET151 and the p38 MAPK inhibitor SB203580 reduced YAP levels in PaSC. Stimulation of PaSC with the potent mitogen PDGF elicited marked YAP Ser127 phosphorylation. However, unexpectedly, this effect did not diminish YAP nuclear localization, suggesting that YAP phosphorylation at this site does not govern YAP cellular localization in PaSC. siRNA-mediated knockdown of YAP reduced PDGF-induced PaSC expansion in culture and blunted the persistent activation of Akt and ERK elicited by PDGF stimulation, supporting a role for YAP in PDGF-induced cell growth. YAP knockdown also blunted fibroinflammatory gene expression responses both in unstimulated and transforming growth factor beta 1 (TGFβ1)-stimulated PaSC. Conclusion: Our data suggest a central role for YAP in sustaining the activated phenotype and fibroinflammatory responses in PaSC. Moreover, our findings indicate that a complex crosstalk between YAP, TGFβ1, and PDGF pathways regulates PaSC activity and growth.

Management of severe acute pancreatitis

The risks, measurements of severity, and management of severe acute pancreatitis and its complications have evolved rapidly over the past decade. Evidence suggests that initial goal directed therapy, nutritional support, and vigilance for pancreatic complications are best practice. Patients can develop pancreatic fluid collections including acute pancreatic fluid collections, pancreatic pseudocysts, acute necrotic collections, and walled-off necrosis. Several randomized controlled trials and cohort studies have recently highlighted the advantage of managing these conditions with a progressive approach, with initial draining for infection followed by less invasive techniques. Surgery is no longer an early intervention and may not be needed. Instead, interventional radiologic and endoscopic methods seem to be safer with at least as good survival outcomes. Newly developed evidence based quality indicators are available to assess and improve performance. Development and clinical testing of drugs to target the mechanisms of disease are necessary for further advancements.

NOD-like receptor C4 Inflammasome Regulates the Growth of Colon Cancer Liver Metastasis in NAFLD

Nonalcoholic fatty liver disease (NAFLD) enhances the growth and recurrence of colorectal cancer (CRC) liver metastasis. With the rising prevalence of NAFLD, a better understanding of the molecular mechanism underlying NAFLD-associated liver metastasis is crucial. Tumor-associated macrophages (TAMs) constitute a large portion of the tumor microenvironment that promotes tumor growth. NOD-like receptor C4 (NLRC4), a component of an inflammasome complex, plays a role in macrophage activation and interleukin (IL)-1β processing. We aimed to investigate whether NLRC4-mediated TAM polarization contributes to metastatic liver tumor growth in NAFLD. Wild-type and NLRC4^-/- mice were fed low-fat or high-fat diet for 6 weeks followed by splenic injection of mouse CRC MC38 cells. The tumors were analyzed 2 weeks after CRC cell injection. High-fat diet-induced NAFLD significantly increased the number and size of CRC liver metastasis. TAMs and CD206-expressing M2 macrophages accumulated markedly in tumors in the presence of NAFLD. NAFLD up-regulated the expression of IL-1β, NLRC4, and M2 markers in tumors. In NAFLD, but not normal livers, deletion of NLRC4 decreased liver tumor growth accompanied by decreased M2 TAMs and IL-1β expression in tumors. Wild-type mice showed increased vascularity and vascular endothelial growth factor (VEGF) expression in tumors with NAFLD, but these were reduced in NLRC4^-/- mice. When IL-1 signaling was blocked by recombinant IL-1 receptor antagonist, liver tumor formation and M2-type macrophages were reduced, suggesting that IL-1 signaling contributes to M2 polarization and tumor growth in NAFLD. Finally, we found that TAMs, but not liver macrophages, produced more IL-1β and VEGF following palmitate challenge. Conclusion: In NAFLD, NLRC4 contributes to M2 polarization, IL-1β, and VEGF production in TAMs, which promote metastatic liver tumor growth.

STING signalling protects against chronic pancreatitis by modulating Th17 response

OBJECTIVE

Chronic pancreatitis (CP) is an inflammatory disease with progressive fibrosis leading to exocrine and endocrine dysfunction. Currently, there are no approved effective therapies for CP. Stimulator of interferon genes (STING) signalling is a key innate immune sensor of DNA. In this study, we evaluated the role of STING signalling in CP.

DESIGN

We used an experimental model of CP to test the effect of STING signalling in STING wild-type and knockout mice as well as bone marrow chimaeras (BMCs). STING was activated using a pharmacological agent. Since we found changes in Th17 cells, we used neutralising and control antibodies to determine the role of IL-17A. The effect of STING signalling was further explored in IL-17A generation and we examined the effect of IL-17A on pancreatic stellate cells (PSCs). Human pancreas from patients with CP and without CP were also stained for IL-17A.

RESULTS

STING activation decreased CP-associated pancreatic inflammation and fibrosis, whereas absence of STING led to worsening of the disease. BMCs showed that leucocytes play an important role in STING signalling-mediated amelioration of experimental CP. STING deletion was associated with increased Th17 cell infiltration in the pancreas, whereas STING agonist limited this Th17 response. Importantly, anti-IL-17A antibody treatment mitigated the severity of CP in the absence of STING signalling. STING deficiency promoted Th17 polarisation and PSCs express functional IL-17 receptor by upregulating fibrosis genes. Compared with tumour margins, pancreas from patients with CP had significant increase in IL-17A+ cells.

CONCLUSION

Unlike acute pancreatitis, STING activation is protective in CP. STING signalling is important in regulating adaptive immune responses by diminishing generation of IL-17A during CP and presents a novel therapeutic target for CP.

Antidiabetic Medications and Mortality Risk in Individuals With Pancreatic Cancer-Related Diabetes and Postpancreatitis Diabetes: A Nationwide Cohort Study

OBJECTIVE

There are no specific treatment guidelines for diabetes of the exocrine pancreas. High-quality studies are warranted to investigate whether the use of antidiabetic medications has survival benefit in individuals with diabetes of the exocrine pancreas. The objective was to determine the risk of mortality associated with the use of antidiabetic medications in individuals with pancreatic cancer-related diabetes (PCRD) and postpancreatitis diabetes mellitus (PPDM).

RESEARCH DESIGN AND METHODS

Nationwide pharmaceutical dispensing data (2006-2015) linked to hospital discharge data were used to identify 1,862 individuals with PCRD or PPDM. Multivariable Cox regression analysis was conducted, and the risk was expressed as hazard ratios and 95% CIs. A 6-month lag was used to minimize reverse causality.

RESULTS

In individuals with PCRD, ever users of metformin (adjusted hazard ratio 0.54; 95% CI 0.46-0.63) and ever users of insulin (adjusted hazard ratio 0.46; 95% CI 0.39-0.55) had significantly lower risks of mortality compared with never users of antidiabetic medications. These associations attenuated toward the null with the use of a 6-month lag. In individuals with PPDM, ever users of metformin had a significantly lower risk of mortality (adjusted hazard ratio 0.51; 95% CI 0.36-0.70), whereas ever-users of insulin did not have a significantly changed risk of mortality (adjusted hazard ratio 0.75; 95% CI 0.49-1.14) compared with never users of antidiabetic medications. The former association remained significant with the use of a 6-month lag.

CONCLUSIONS

Metformin promotes a survival benefit in individuals with PPDM but not PCRD. Reverse causality may play a role in the association between insulin use and mortality in PCRD.

Simvastatin induces autophagic flux to restore cerulein-impaired phagosome-lysosome fusion in acute pancreatitis

BACKGROUND

During pancreatitis, autophagy is activated, but lysosomal degradation of dysfunctional organelles including mitochondria is impaired, resulting in acinar cell death. Retrospective cohort analyses demonstrated an association between simvastatin use and decreased acute pancreatitis incidence.

METHODS

We examined whether simvastatin can protect cell death induced by cerulein and the mechanisms involved during acute pancreatitis. Mice were pretreated with DMSO or simvastatin (20 mg/kg) for 24 h followed by 7 hourly cerulein injections and sacrificed 1 h after last injection to harvest blood and tissue for analysis.

RESULTS

Pancreatic histopathology revealed that simvastatin reduced necrotic cell death, inflammatory cell infiltration and edema. We found that cerulein triggered mitophagy with autophagosome formation in acinar cells. However, autophagosome-lysosome fusion was impaired due to altered levels of LAMP-1, AMPK and ULK-1, resulting in autophagosome accumulation (incomplete autophagy). Simvastatin abrogated these effects by upregulating LAMP-1 and activating AMPK which phosphorylated ULK-1, resulting in increased formation of functional autolysosomes. In contrast, autophagosomes accumulated in control group during pancreatitis. The effects of simvastatin to promote autophagic flux were inhibited by chloroquine. Mitochondria from simvastatin-treated mice were resistant to calcium overload compared to control, suggesting that simvastatin induced mitochondrial quality control to eliminate susceptible mitochondria. Clinical specimens showed a significant increase in cell-free mtDNA in plasma during pancreatitis compared to normal controls. Furthermore, genetic deletion of parkin abrogated the benefits of simvastatin.

CONCLUSION

Our findings reveal the novel role of simvastatin in enhancing autophagic flux to prevent pancreatic cell injury and pancreatitis.