Pancreatic development and disease

Ectopic pancreatic tissue in the small intestine: An uncommon finding following trauma

INTRODUCTION

Ectopic pancreatic tissue (EPT), also known as Heterotopic pancreas (HP), is a rare congenital anomaly characterized by the presence of pancreatic tissue outside the primary organ. This report presents a case of EPT incidentally discovered in the submucosal area of the small intestine.

CASE PRESENTATION

A 56-year-old male presented to the emergency department following a high-speed car collision, reporting abdominal pain after impact with the steering wheel. Physical examination revealed left upper quadrant tenderness. Imaging studies showed free fluid in the abdominal and pelvic cavities, mesenteric damage, and increased intestinal wall thickness. Surgical exploration confirmed hemoperitoneum and a non-viable 30 cm segment of the small intestine, which was resected. Subsequent pathological examination revealed a 1.5 cm submucosal mass, diagnosed as EPT. The patient recovered uneventfully and was discharged in stable condition.

CLINICAL DISCUSSION

Clinically significant lesions are typically larger than 1.5 cm and involve the mucosa, with pain as the most common symptom. They can also cause severe complications such as intestinal obstruction, perforation, peritonitis, and gastrointestinal bleeding. Additionally, EPT can be associated with malignant transformations.

CONCLUSION

While often asymptomatic, EPT can lead to significant complications, making surgical resection essential for both symptomatic and incidental cases, particularly since diagnosis is frequently established postoperatively through histological examination. Although trauma may not directly cause EPT, its management in emergency settings can facilitate evaluations that reveal lesions capable of causing severe complications if left undiagnosed. Given the diverse symptoms associated with this condition, EPT should be considered in the differential diagnosis of intestinal lesions.

Pancreatic Differentiation of Oral Minor Salivary Gland Stem Cells

INTRODUCTION

Stem cells from various sources including major salivary glands have been used to establish pancreatic differentiation in an attempt to provide new treatment options for patients with diabetes mellitus. In contrast, the potential of using the more easily accessible intraoral minor salivary glands has not been evaluated so far.

MATERIALS AND METHODS

Salivary stem cells were isolated from normal labial minor salivary glands that were removed during the excision of a mucocele and were attempted to differentiate into pancreatic cell lines using a culture medium enriched with activin A, retinoic acid and GLP-1.Real time RT-PCR was used to evaluate the expression of the genes of pancreatic transcription factors MafA, Ptf1a, Hb9 and Arx. Complementary, 22 labial minor salivary gland paraffin-embedded specimens were examined using immunohistochemistry for the presence of the relevant gene products of the pancreatic transcription factors Arx, MafA, Ptf1a and Pdx1.

RESULTS

The differentiated salivary stem cells(cells of passage 3) expressed the genes of the pancreatic transcription factors MafA, Ptf1a, Hb9 and Arx even on the first day of the experiment while immunohistochemistry also confirmed the presence of the protein products of Arx, MafA, Ptf1a as well as Pdx1[> 50% of the specimens for Arx(5/8) and MafA(7/8), < 50% for Ptf1a(5/11) and Pdx1(5/11)] in ducts, mesenchymal connective tissue and acinar cells.

CONCLUSIONS

Labial minor salivary glands may share gene and protein characteristics with pancreas suggesting a possible usefulness for pancreatic regeneration or substitution in cases of deficiency.

Ansa Pancreatica: A Rare Culprit in Recurrent Acute Pancreatitis

Ansa pancreatica is a rare anatomical variation of the pancreatic duct system, characterized by a reversed S-shaped loop that connects the main pancreatic duct to the minor papilla. Its clinical significance, particularly with recurrent acute pancreatitis, has been a subject of interest, but remains poorly understood due to the rarity of reported cases. We report the case of a 34-year-old female with a history of multiple episodes of acute pancreatitis, diagnosed with ansa pancreatica using magnetic resonance cholangiopancreatography (MRCP). The patient presented with severe epigastric pain radiating to the back, accompanied by vomiting and nausea. Laboratory findings revealed elevated serum amylase and lipase levels. MRCP imaging identified the ansa pancreatica, showing a distinct looping ductal variant terminating near the minor papilla. The patient underwent successful endoscopic treatment with significant improvement in symptoms and no recurrence of pancreatitis at follow-up. In this case, the presence of ansa pancreatica underscores the variant's potential role in predisposing individuals to recurrent episodes of acute pancreatitis. The literature review highlights the anatomical description of ansa pancreatica and its speculated pathophysiological mechanism leading to pancreatitis, primarily due to impaired pancreatic juice drainage. Despite its rarity, recognizing ansa pancreatica is crucial for the appropriate management of idiopathic recurrent pancreatitis, especially in cases where conventional causes are absent. This case report and literature review emphasize the importance of considering ansa pancreatica in the differential diagnosis of recurrent acute pancreatitis. Further research is needed to elucidate the exact mechanism by which this anatomical variant contributes to pancreatitis and to explore potential therapeutic interventions. Awareness and early detection of ansa pancreatica can lead to targeted treatments, reducing the morbidity associated with recurrent pancreatitis episodes.

Exocrine Pancreatic Insufficiency in Children - Challenges in Management

Cystic fibrosis (CF) is the leading etiology for exocrine pancreatic insufficiency (EPI) in children, followed by chronic pancreatitis, Shwachman-Diamond syndrome, and other genetic disorders. Management of EPI in children poses several unique challenges such as difficulties in early recognition, lack of widespread availability of diagnostic tests and limited number of pediatric-specific pancreatic centers. Pancreatic enzyme replacement therapy is the cornerstone of EPI management and in young children difficulties in administering pancreatic enzymes are frequently encountered. Patients with EPI also should be screened for fat-soluble vitamin deficiencies and receive appropriate supplementation. Among disorders with EPI in children, CF is the relatively well-studied condition, and most management recommendations for EPI in children come from expert consensus and conventional practice guidelines. The impact of EPI can be greater in children given their high metabolic demands and rapid growth. Early diagnosis and aggressive management of EPI prevent consequences of complications such as malnutrition, fat-soluble vitamin deficiencies, and poor bone health and improve outcomes. Management by multi-disciplinary team is the key to success.

Adar1 deletion causes degeneration of the exocrine pancreas via Mavs-dependent interferon signaling

Adenosine deaminase acting on RNA 1 (ADAR1) is an RNA-binding protein that deaminates adenosine (A) to inosine (I). A-to-I editing alters post-transcriptional RNA processing, making ADAR1 a crucial regulator of gene expression. Consequently, Adar1 has been implicated in organogenesis. To determine the role of Adar1 in pancreatic development and homeostasis, we conditionally deleted Adar1 from the murine pancreas (Ptf1aCre/+; Adar1Fl/Fl). The resulting mice had stunted growth, likely due to malabsorption associated with exocrine pancreatic insufficiency. Analyses of pancreata revealed ductal cell expansion, heightened interferon-stimulated gene expression and an increased influx of immune cells. Concurrent deletion of Adar1 and Mavs, a signaling protein implicated in the innate immune pathway, rescued the degenerative phenotype and resulted in normal pancreatic development. Taken together, our work suggests that the primary function of Adar1 in the pancreas is to prevent aberrant activation of the Mavs-mediated innate immune pathway, thereby maintaining pancreatic homeostasis.

Enzobiotics-A Novel Therapy for the Elimination of Uremic Toxins in Patients with CKD (EETOX Study): A Multicenter Double-Blind Randomized Controlled Trial

Design, participants, setting, and measurements: Predialysis adult participants with chronic kidney disease (CKD) and mean estimated glomerular filtration rate (eGFR) <45 mL/min per 1.73 m2) were recruited in 2019 to a multicentric double-blinded randomized controlled trial of enzobiotic therapy (synbiotics and proteolytic enzymes) conducted over 12 weeks. The primary objective was to evaluate the efficacy and safety of enzobiotics in reducing the generation of p-cresol sulfate (PCS) and indoxyl sulfate (IS), stabilizing renal function, and improving quality of life (QoL), while the secondary objective was to evaluate the feasibility of the diagnostic prediction of IS and PCS from CKD parameters. Results: Of the 85 patients randomized (age 48.76 years, mean eGFR 23.24 mL/min per 1.73 m2 in the placebo group; age 54.03 years, eGFR 28.93 mL/min per 1.73 m2 in the enzobiotic group), 50 completed the study. The absolute mean value of PCS increased by 12% from 19 µg/mL (Day 0) to 21 µg/mL (Day90) for the placebo group, whereas it decreased by 31% from 23 µg/mL (Day 0) to 16 µg/mL (Day 90) for the enzobiotic group. For IS, the enzobiotic group showed a decrease (6.7%) from 11,668 to 10,888 ng/mL, whereas the placebo group showed an increase (8.8%) from 11,462 to 12,466 ng/mL (Day 90). Each patient improvement ratio for Day 90/Day 0 analysis showed that enzobiotics reduced PCS by 23% (0.77, p = 0.01). IS levels remained unchanged. In the placebo group, PCS increased by 27% (1.27, p = 0.14) and IS increased by 20% (1.20, p = 0.14). The proportion of individuals beyond the risk threshold for PCS (>20 µg/mL) was 53% for the placebo group and 32% for the enzobiotic group. The corresponding levels for IS risk (threshold >20,000 ng/mL) were 35% and 24% for the placebo and enzobiotic groups, respectively. In the placebo group, eGFR decreased by 7% (Day 90) but remained stable (1.00) in the enzobiotic group. QoL as assessed by the adversity ratio decreased significantly (p = 0.00), highlighting an improvement in the enzobiotic group compared to the placebo group. The predictive equations were as follows: PCS (Day 0 = −5.97 + 0.0453 PC + 2.987 UA − 1.310 Creat; IS (Day 0) = 756 + 1143 Creat + 436.0 Creat2. Conclusion: Enzobiotics significantly reduced the PCS and IS, as well as improved the QoL.

Pancreatic Heterotopia in the Small Bowel: A Case Report and Literature Review

ABSTRACT

Diagnosing pancreatic heterotopia (PH) is challenging, because it is a rare congenital anomaly. We report the case of a 66-year-old man who presented with ileus and jejunal PH diagnosed using single-balloon enteroscopy. Reviewing 178 cases of small intestinal PH in the literature showed that (1) PH mostly occurred at the duodenum (61.8%), followed by the jejunum (22.5%) and ileum (14.6%); (2) patients with ileal PH were younger (mean, 40.7 vs 54.6 years; P < 0.001), while those with jejunal PH were older (mean, 59.5 vs 51.7 years; P = 0.006); (3) most patients with jejunal PH were females, while those with duodenal or ileal PH were predominantly males (M:F = 0.8:1 vs 2.5:1; P = 0.003); (4) asymptomatic cases were rare (15.2% vs 83.4% in small and nonsmall bowel, respectively); (5) most patients with ileal PH presented with bleeding (61.5%), while the remaining had abdominal pain (42.8%); (6) emergent operation was performed in 11 cases (6.2%), mainly at the jejunum (12.5%) and Meckel's diverticulum (25%); and (7) Heinrich's classification may be inconclusive. Enteroscopy was performed in only 6 cases (3.4%), and earlier diagnosis and further minimally invasive procedures could have been achieved with enteroscopy.

Agenesis of the dorsal pancreas with chronic suppurative pancreatitis: Case report and literature review

RATIONALE

Agenesis of the dorsal pancreas (ADP) is a rare congenital anomaly of the pancreas. ADP is associated with some other medical problems such as diabetes mellitus, abdominal pain/bloating, pancreatitis, pancreatic neuroendocrine tumor and so on. In this study, we present a case of ADP with chronic suppurative pancreatitis, summarize the clinical characteristics of the reported cases in China and review the correlative literature.

PATIENT CONCERNS

A 51-year-old Chinese man, with a history of impaired fasting glucose, presented with jaundice, pruritus and dark urine. Laboratory analysis showed abnormal liver function and elevated carbohydrate antigen 19-9.

DIAGNOSES

Contrast-enhanced computed tomography demonstrated a mass located at the head of pancreas and complete absence of the body and tail of pancreas. Endoscopic retrograde cholangiopancreatography demonstrated an eccentric malignant stricture about 1.6cm of distal common bile duct.

INTERVENTIONS

The patient underwent pancreaticoduodenectomy because of the suspicion of pancreatic tumor. The postoperative pathological result was chronic suppurative pancreatitis, with moderate hyperplasia in focal ductal epithelium.

OUTCOMES

A long-term follow-up shows that the patient is asymptomatic with well-controlled diabetes mellitus and pancreatic exocrine insufficiency.

LESSONS

ADP is a quite rare congenital malformation of the pancreas with poorly-understood pathogenesis. The diagnosis of ADP depends on the imaging examination. The therapeutic strategy varies from person to person due to the different accompanying conditions.

Transcriptome analysis of the transdifferentiation of canine BMSCs into insulin producing cells

Background

Bone marrow mesenchymal stem cells are a potential resource for the clinical therapy of certain diseases. Canine, as a companion animal, living in the same space with human, is an ideal new model for human diseases research. Because of the high prevalence of diabetes, alternative transplantation islets resource (i.e. insulin producing cells) for diabetes treatment will be in urgent need, which makes our research on the transdifferentiation of Bone marrow mesenchymal stem cells into insulin producing cells become more important.

Result

In this study, we completed the transdifferentiation process and achieved the transcriptome profiling of five samples with two biological duplicates, namely, “BMSCs”, “islets”, “stage 1”, “stage 2” and “stage 3”, and the latter three samples were achieved on the second, fifth and eighth day of induction. A total of 11,530 differentially expressed transcripts were revealed in the profiling data. The enrichment analysis of differentially expressed genes revealed several signaling pathways that are essential for regulating proliferation and transdifferentiation, including focal adhesion, ECM-receptor interaction, tight junction, protein digestion and absorption, and the Rap1 signaling pathway. Meanwhile, the obtained protein–protein interaction network and functional identification indicating involvement of three genes, SSTR2, RPS6KA6, and VIP could act as a foundation for further research.

Conclusion

In conclusion, to the best of our knowledge, this is the first survey of the transdifferentiation of canine BMSCs into insulin-producing cells according with the timeline using next-generation sequencing technology. The three key genes we pick out may regulate decisive genes during the development of transdifferentiation of insulin producing cells.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12864-021-07426-3.

Animal Models of Pancreas Development, Developmental Disorders, and Disease

The pancreas is a glandular organ responsible for diverse homeostatic functions, including hormone production from the endocrine islet cells to regulate blood sugar levels and enzyme secretion from the exocrine acinar cells to facilitate food digestion. These pancreatic functions are essential for life; therefore, preserving pancreatic function is of utmost importance. Pancreas dysfunction can arise either from developmental disorders or adult onset disease, both of which are caused by defects in shared molecular pathways. In this chapter, we discuss what is known about the molecular mechanisms controlling pancreas development, how disruption of these mechanisms can lead to developmental defects and disease, and how essential pancreas functions can be modeled using human pluripotent stem cells. At the core of understanding of these molecular processes are animal model studies that continue to be essential for elucidating the mechanisms underlying human pancreatic functions and diseases.

A case report and literature review: incidental jejunal ectopic pancreatic tissue in an emergency bowel exploration for suspected intussusception

Heterotopic pancreas (HP) is defined as pancreatic tissue which is an anatomically separate entity from the main pancreas and free from the organ's vascular or ductal continuity. Most cases of HP are asymptomatic and are diagnosed incidentally upon laparotomy or on autopsy. The diagnosis of HP can be extremely difficult. A few imaging modalities which include Magnetic resonance imaging (MRI) and magnetic resonance cholangiopancreatography (MRCP) may show characteristic features of HP. However, definitive diagnosis is made by histopathology. Conversely, these modalities may not differentiate a malignant neoplasm from a benign mass. Surgical excision is thought to be curative for HP. In this case report, we present a 62-year-old female with acute myelocytic leukemia on induction chemotherapy who developed abdominal pain during her hospital admission and was referred to the general surgery department. Abdominal computed tomography (CT) was done and showed signs of small bowel obstruction, perforation, and overlapping jejunoileal segments suggestive of intussusception. Upon surgical exploration two small bowel perforations were repaired, one iatrogenic and one pathological. On bowel run a jejunal mass was found, excised, and upon histopathology confirmed to be a mixed endocrine and exocrine heterotopic pancreatic choristoma. Definitive diagnosis of heterotopic pancreatic tissue is made by histopathology, and surgical excision is potentially curative. In conclusion, we recommend excising HP if found incidentally upon surgery as the diagnosis of HP and exclusion of neoplasm may not be possible without a histological specimen.

SOX9 Stem-Cell Factor: Clinical and Functional Relevance in Cancer

Transcriptional and epigenetic embryonic programs can be reactivated in cancer cells. As result, a specific subset of undifferentiated cells with stem-cells properties emerges and drives tumorigenesis. Recent findings have shown that ectoderm- and endoderm-derived tissues continue expressing stem-cells related transcription factors of the SOX-family of proteins such as SOX2 and SOX9 which have been implicated in the presence of cancer stem-like cells (CSCs) in tumors. Currently, there is enough evidence suggesting an oncogenic role for SOX9 in different types of human cancers. This review provides a summary of the current knowledge about the involvement of SOX9 in development and progression of cancer. Understanding the functional roles of SOX9 and clinical relevance is crucial for developing novel treatments targeting CSCs in cancer.

Quercetin improves endothelial function in diabetic rats through inhibition of endoplasmic reticulum stress-mediated oxidative stress

Endoplasmic reticulum (ER) stress attributes a crucial role in diabetes-induced endothelial dysfunction. The present study investigated the effects of quercetin, a potent antioxidant on the attenuation of ER stress-modulated endothelial dysfunction in streptozotocin (STZ)-induced diabetic rats. Oral administration of quercetin for six weeks to diabetic rats dose-dependently reduced the blood glucose levels and improved insulin secretion. Histopathological examination of pancreatic tissues in diabetic rats showed pathological changes such as shrunken islets, reduction in islet area and distorted β-cells, which were found to be restored by quercetin treatment. In addition, quercetin reduced the pancreatic ER stress-induced endothelial dysfunction as assessed by immunohistochemical analysis of C/ERB homologous protein (CHOP) and endothelin-1 (ET-1). Moreover, quercetin administration progressively increased the expression of vascular endothelial growth factor (VEGF) and its receptor, VEGFR2 in diabetes rats. Quercetin-mediated decrease in the nitric oxide (NO∙) and cyclic 3',5'- guanosine monophosphate (cGMP) levels were also observed in the diabetic rats. Quercetin treatment reduced the lipid peroxidation in the diabetic rats, meanwhile increased the total antioxidant capacity in the pancreas from diabetic rats. Altogether, these results demonstrated the vasoprotective effect of quercetin against STZ-induced ER stress in the pancreas of diabetic rats.

Agenesis of the dorsal pancreas: systematic review of a clinical challenge

BACKGROUND

Agenesis of the dorsal pancreas is a rare malformation. Since 1911 and until 2008, 53 cases have been reported. Several authors have recently described the association of this anomaly with neoplasia of the ventral pancreas, thus we performed a systematic review of the literature from 2008 to 2015.

METHODS

A systematic review of the MedLine and ISI Web of Science Databases from 2008 until 2015 was carried out, and 30 articles which met the inclusion criteria were identified that included a total of 53 patients: 7 children and 46 adults.

CONCLUSIONS

Although dorsal pancreatic agenesis is a rare malformation, given its association with non-alcoholic pancreatitis and neoplasia of the residual pancreas, physicians should maintain an expectant attitude.

Epithelial-Myeloid cell crosstalk regulates acinar cell plasticity and pancreatic remodeling in mice

Dedifferentiation of acini to duct-like cells occurs during the physiologic damage response in the pancreas, but this process can be co-opted by oncogenic Kras to drive carcinogenesis. Myeloid cells infiltrate the pancreas during the onset of pancreatic cancer, and promote carcinogenesis. Here, we show that the function of infiltrating myeloid cells is regulated by oncogenic Kras expressed in epithelial cells. In the presence of oncogenic Kras, myeloid cells promote acinar dedifferentiation and carcinogenesis. Upon inactivation of oncogenic Kras, myeloid cells promote re-differentiation of acinar cells, remodeling of the fibrotic stroma and tissue repair. Intriguingly, both aspects of myeloid cell activity depend, at least in part, on activation of EGFR/MAPK signaling, with different subsets of ligands and receptors in different target cells promoting carcinogenesis or repair, respectively. Thus, the cross-talk between epithelial cells and infiltrating myeloid cells determines the balance between tissue repair and carcinogenesis in the pancreas.

Glycogen synthase kinase-3β ablation limits pancreatitis-induced acinar-to-ductal metaplasia

Acinar-to-ductal metaplasia (ADM) is a reversible epithelial transdifferentiation process that occurs in the pancreas in response to acute inflammation. ADM can rapidly progress towards pre-malignant pancreatic intraepithelial neoplasia (PanIN) lesions in the presence of mutant KRas and ultimately pancreatic adenocarcinoma (PDAC). In the present work, we elucidate the role and related mechanism of glycogen synthase kinase-3beta (GSK-3β) in ADM development using in vitro 3D cultures and genetically engineered mouse models. We show that GSK-3β promotes TGF-α-induced ADM in 3D cultured primary acinar cells, whereas deletion of GSK-3β attenuates caerulein-induced ADM formation and PanIN progression in Kras^G12D transgenic mice. Furthermore, we demonstrate that GSK-3β ablation influences ADM formation and PanIN progression by suppressing oncogenic KRas-driven cell proliferation. Mechanistically, we show that GSK-3β regulates proliferation by increasing the activation of S6 kinase. Taken together, these results indicate that GSK-3β participates in early pancreatitis-induced ADM and thus could be a target for the treatment of chronic pancreatitis and the prevention of PDAC progression. Copyright © 2017 Pathological Society of Great Britain and Ireland. Published by John Wiley & Sons, Ltd.

Clinical impact of duodenal pancreatic heterotopia - Is there a need for surgical treatment?

BACKGROUND

Pancreatic heterotopia (PH) is defined as ectopic pancreatic tissue outside the normal pancreas and its vasculature and duct system. Most frequently, PH is detected incidentally by histopathological examination. The aim of the present study was to analyze a large single-center series of duodenal PH with respect to the clinical presentation.

METHODS

A prospective pancreatic database was retrospectively analyzed for cases of PH of the duodenum. All pancreatic and duodenal resections performed between January 2000 and October 2015 were included and screened for histopathologically proven duodenal PH. PH was classified according to Heinrich's classification (Type I acini, ducts, and islet cells; Type II acini and ducts; Type III only ducts).

RESULTS

A total of 1274 pancreatic and duodenal resections were performed within the study period, and 67 cases of PH (5.3%) were identified. The respective patients were predominantly male (72%) and either underwent pancreatoduodenectomy (n = 60); a limited pancreas resection with partial duodenal resection (n = 4); distal pancreatectomy with partial duodenal resection (n = 1); total pancreatectomy (n = 1); or enucleation (n = 1). Whereas 65 patients (83.5%) were asymptomatic, 11 patients (18.4%) presented with symptoms related to PH (most frequently with abdominal pain [72%] and duodenal obstruction [55%]). Of those, seven patients (63.6%) had chronic pancreatitis in the heterotopic pancreas. The risk of malignant transformation into adenocarcinoma was 2.9%.

CONCLUSIONS

PH is found in approximately 5% of pancreatic or duodenal resections and is generally asymptomatic. Chronic pancreatitis is not uncommon in heterotopic pancreatic tissue, and even there is a risk of malignant transformation. PH should be considered for the differential diagnosis of duodenal lesions and surgery should be considered, especially in symptomatic cases.

Agenesis of the dorsal pancreas associated with mucinous adenocarcinoma and cystic teratoma: a case report and literature review

Dorsal agenesis of the pancreas is a rare congenital anomaly. Fifty‐eight cases were reported from 1913 till 2015, nine of which were associated with tumors. We present the 10th case, the first to be associated with pancreatic mucinous adenocarcinoma and cystic teratoma, successfully managed by Whipple procedure and total pancreatectomy.

Monitoring p53 by MDM2 and MDMX is required for endocrine pancreas development and function in a spatio-temporal manner

Although p53 is not essential for normal embryonic development, it plays a pivotal role in many biological and pathological processes, including cell fate determination-dependent and independent events and diseases. The expression and activity of p53 largely depend on its two biological inhibitors, MDM2 and MDMX, which have been shown to form a complex in order to tightly control p53 to an undetectable level during early stages of embryonic development. However, more delicate studies using conditional gene-modification mouse models show that MDM2 and MDMX may function separately or synergistically on p53 regulation during later stages of embryonic development and adulthood in a cell and tissue-specific manner. Here, we report the role of the MDM2/MDMX-p53 pathway in pancreatic islet morphogenesis and functional maintenance, using mouse lines with specific deletion of MDM2 or MDMX in pancreatic endocrine progenitor cells. Interestingly, deletion of MDM2 results in defects of embryonic endocrine pancreas development, followed by neonatal hyperglycemia and lethality, by inducing pancreatic progenitor cell apoptosis and inhibiting cell proliferation. However, unlike MDM2-knockout animals, mice lacking MDMX in endocrine progenitor cells develop normally. But, surprisingly, the survival rate of adult MDMX-knockout mice drastically declines compared to control mice, as blockage of neonatal development of endocrine pancreas by inhibition of cell proliferation and subsequent islet dysfunction and hyperglycemia eventually lead to type 1 diabetes-like disease with advanced diabetic nephropathy. As expected, both MDM2 and MDMX deletion-caused pancreatic defects are completely rescued by loss of p53, verifying the crucial role of the MDM2 and/or MDMX in regulating p53 in a spatio-temporal manner during the development, functional maintenance, and related disease progress of endocrine pancreas. Also, our study suggests a possible mouse model of advanced diabetic nephropathy, which is complementary to other established diabetic models and perhaps useful for the development of anti-diabetes therapies.

Loss of Pancreas upon Activated Wnt Signaling Is Concomitant with Emergence of Gastrointestinal Identity

Organ formation is achieved through the complex interplay between signaling pathways and transcriptional cascades. The canonical Wnt signaling pathway plays multiple roles during embryonic development including patterning, proliferation and differentiation in distinct tissues. Previous studies have established the importance of this pathway at multiple stages of pancreas formation as well as in postnatal organ function and homeostasis. In mice, gain-of-function experiments have demonstrated that activation of the canonical Wnt pathway results in pancreatic hypoplasia, a phenomenon whose underlying mechanisms remains to be elucidated. Here, we show that ectopic activation of epithelial canonical Wnt signaling causes aberrant induction of gastric and intestinal markers both in the pancreatic epithelium and mesenchyme, leading to the development of gut-like features. Furthermore, we provide evidence that β -catenin-induced impairment of pancreas formation depends on Hedgehog signaling. Together, our data emphasize the developmental plasticity of pancreatic progenitors and further underscore the key role of precise regulation of signaling pathways to maintain appropriate organ boundaries.

Increased 18F-FDG uptake of heterotopic pancreatitis in the small intestine: A CARE-compliant case report

BACKGROUD

Heterotopic pancreas (HP), a relatively uncommon congenital anomaly, is rarely noted during F-FDG positron-emission tomography/computed tomography (PET/CT) scan.

METHODS

A 60-year-old woman was referred to our hospital due to a 10-day history of abdominal pain with elevated levels of serum amylase and lipase. Abdominal CT and ultrasound examinations were negative. In order to search for the cause, an F-FDG PET/CT whole body scan was suggested to an old woman revealing the presence of F-FDG accumulating nodule in small intestine.

RESULTS

Surgical findings and pathologic results confirmed the diagnosis of small intestinal heterotopic pancreas with active chronic inflammation.

CONCLUSION

This uncommon case underscores the necessity of considering heterotopic pancreatitis in small intestine with focal F-FDG uptake as a possible differential diagnosis in intestinal tumor and tuberculosis.

Concise Review: Pancreatic Cancer and Bone Marrow-Derived Stem Cells

Pancreatic adenocarcinoma remains one of the most challenging diseases of modern gastroenterology, and, even though considerable effort has been put into understanding its pathogenesis, the exact molecular mechanisms underlying the development and/or systemic progression of this malignancy still remain unclear. Recently, much attention has been paid to the potential role of bone marrow-derived stem cells (BMSCs) in this malignancy. Hence, herein, we comprehensively review the most recent discoveries and current achievements and concepts in this field. Specifically, we discuss the significance of identifying pancreatic cancer stem cells and novel therapeutic approaches involving molecular interference of their metabolism. We also describe advances in the current understanding of the biochemical and molecular mechanisms responsible for BMSC mobilization during pancreatic cancer development and systemic spread. Finally, we summarize experimental, translational, and/or clinical evidence regarding the contribution of bone marrow-derived mesenchymal stem cells, endothelial progenitor cells, hematopoietic stem/progenitor cells, and pancreatic stellate cells in pancreatic cancer development/progression. We also present their potential therapeutic value for the treatment of this deadly malignancy in humans.

SIGNIFICANCE

Different bone marrow-derived stem cell populations contribute to the development and/or progression of pancreatic cancer, and they might also be a promising "weapon" that can be used for anticancer treatments in humans. Even though the exact role of these stem cells in pancreatic cancer development and/or progression in humans still remains unclear, this concept continues to drive a completely novel scientific avenue in pancreatic cancer research and gives rise to innovative ideas regarding novel therapeutic modalities that can be safely offered to patients.

Differential role of Hedgehog signaling in human pancreatic (patho-) physiology: An up to date review

Since the discovery of the Hedgehog (Hh) pathway in drosophila melanogaster, our knowledge of the role of Hh in embryonic development, inflammation, and cancerogenesis in humans has dramatically increased over the last decades. This is the case especially concerning the pancreas, however, real therapeutic breakthroughs are missing until now. In general, Hh signaling is essential for pancreatic organogenesis, development, and tissue maturation. In the case of acute pancreatitis, Hh has a protective role, whereas in chronic pancreatitis, Hh interacts with pancreatic stellate cells, leading to destructive parenchym fibrosis and atrophy, as well as to irregular tissue remodeling with potency of initiating cancerogenesis. In vitro and in situ analysis of Hh in pancreatic cancer revealed that the Hh pathway participates in the development of pancreatic precursor lesions and ductal adenocarcinoma including critical interactions with the tumor microenvironment. The application of specific inhibitors of components of the Hh pathway is currently subject of ongoing clinical trials (phases 1 and 2). Furthermore, a combination of Hh pathway inhibitors and established chemotherapeutic drugs could also represent a promising therapeutic approach. In this review, we give a structured survey of the role of the Hh pathway in pancreatic development, pancreatitis, pancreatic carcinogenesis and pancreatic cancer as well as an overview of current clinical trials concerning Hh pathway inhibitors and pancreas cancer.

The role of endothelial cells on islet function and revascularization after islet transplantation

Islet transplantation has become a widely accepted therapeutic option for selected patients with type 1 diabetes mellitus. However, in order to achieve insulin independence a great number of islets are often pooled from 2 to 4 pancreata donors. Mostly, it is due to the massive loss of islets immediately after transplant. The endothelium plays a key role in the function of native islets and during the revascularization process after islet transplantation. However, if a delayed revascularization occurs, even the remaining islets will also undergo to cell death and late graft dysfunction. Therefore, it is essential to understand how the signals are released from endothelial cells, which might regulate both differentiation of pancreatic progenitors and thereby maintenance of the graft function. New strategies to facilitate islet engraftment and a prompt revascularization could be designed to intervene and might lead to improve future results of islet transplantation.

Frogs as integrative models for understanding digestive organ development and evolution

The digestive system comprises numerous cells, tissues and organs that are essential for the proper assimilation of nutrients and energy. Many aspects of digestive organ function are highly conserved among vertebrates, yet the final anatomical configuration of the gut varies widely between species, especially those with different diets. Improved understanding of the complex molecular and cellular events that orchestrate digestive organ development is pertinent to many areas of biology and medicine, including the regeneration or replacement of diseased organs, the etiology of digestive organ birth defects, and the evolution of specialized features of digestive anatomy. In this review, we highlight specific examples of how investigations using Xenopus laevis frog embryos have revealed insight into the molecular and cellular dynamics of digestive organ patterning and morphogenesis that would have been difficult to obtain in other animal models. Additionally, we discuss recent studies of gut development in non-model frog species with unique feeding strategies, such as Lepidobatrachus laevis and Eleutherodactylous coqui, which are beginning to provide glimpses of the evolutionary mechanisms that may generate morphological variation in the digestive tract. The unparalleled experimental versatility of frog embryos make them excellent, integrative models for studying digestive organ development across multiple disciplines.

Comparisons of Differentiation Potential in Human Mesenchymal Stem Cells from Wharton's Jelly, Bone Marrow, and Pancreatic Tissues

Background. Type 1 diabetes mellitus results from autoimmune destruction of β-cells. Insulin-producing cells (IPCs) differentiated from mesenchymal stem cells (MSCs) in human tissues decrease blood glucose levels and improve survival in diabetic rats. We compared the differential ability and the curative effect of IPCs from three types of human tissue to determine the ideal source of cell therapy for diabetes. Methods. We induced MSCs from Wharton's jelly (WJ), bone marrow (BM), and surgically resected pancreatic tissue to differentiate into IPCs. The in vitro differential function of these IPCs was compared by insulin-to-DNA ratios and C-peptide levels after glucose challenge. In vivo curative effects of IPCs transplanted into diabetic rats were monitored by weekly blood glucose measurement. Results. WJ-MSCs showed better proliferation and differentiation potential than pancreatic MSCs and BM-MSCs. In vivo, WJ-IPCs significantly reduced blood glucose levels at first week after transplantation and maintained significant decrease till week 8. BM-IPCs reduced blood glucose levels at first week but gradually increased since week 3. In resected pancreas-IPCs group, blood glucose levels were significantly reduced till two weeks after transplantation and gradually increased since week 4. Conclusion. WJ-MSCs are the most promising stem cell source for β-cell regeneration in diabetes treatment.

Asymptomatic heterotopic pancreas in Meckel's diverticulum: a case report and review of the literature

Introduction

Heterotopic pancreas is defined as pancreatic tissue without a real anatomical or vascular connection to the pancreas. It can be found in the stomach, duodenum, jejunum, ileum, Meckel’s diverticulum, colon gall bladder, umbilicus, fallopian tube, mediastinum, spleen and liver. Complications of heterotopic pancreas are inflammation, bleeding, obstruction, malignant transformation, carcinoid syndrome, jejunojejunal intussusception and ileus, but it is usually asymptomatic and diagnosed only during examinations for other diseases.

Case presentation

An 81-year-old Lithuanian woman was diagnosed with caecal cancer and had undergone elective surgery. A right hemicolectomy was performed and a Meckel’s diverticulum was observed and excised. Histological results showed a poorly differentiated G3 adenocarcinoma of her large intestine and heterotopic pancreas tissue in the Meckel’s diverticulum and mesenteric adipose tissue.

Conclusions

Asymptomatic heterotopic pancreas is rarely diagnosed, and usually found incidentally during surgical or diagnostic interventions. Although it has no symptoms, heterotopic pancreas found during surgical procedures should be excised.

Xenopus as a Model for GI/Pancreas Disease

Diseases affecting endodermal organs like the pancreas, lung and gastrointestinal (GI) tract have a substantial impact on human welfare. Since many of these are congenital defects that arise as a result of defects during development broad efforts are focused on understanding the development of these organs so as to better identify risk factors, disease mechanisms and therapeutic targets. Studies implementing model systems, like the amphibian Xenopus, have contributed immensely to our understanding of signaling (e.g. Wnt, FGF, BMP, RA) pathways and gene regulation (e.g. hhex, ptf1a, ngn3) that underlie normal development as well as disease progression. Recent advances in genome engineering further enhance the capabilities of the Xenopus model system for pursuing biomedical research, and will undoubtedly result in a boom of new information underlying disease mechanisms ultimately leading to advancements in diagnosis and therapy.

Lhx4 deficiency: increased cyclin-dependent kinase inhibitor expression and pituitary hypoplasia

Defects in the Lhx4, Lhx3, and Pitx2 genes can cause combined pituitary hormone deficiency and pituitary hypoplasia in both humans and mice. Not much is known about the mechanism underlying hypoplasia in these mutants beyond generally increased cell death and poorly maintained proliferation. We identified both common and unique abnormalities in developmental regulation of key cell cycle regulator gene expression in each of these three mutants. All three mutants exhibit reduced expression of the proliferative marker Ki67 and the transitional marker p57. We discovered that expression of the cyclin-dependent kinase inhibitor 1a (Cdkn1a or p21) is expanded dorsally in the pituitary primordium of both Lhx3 and Lhx4 mutants. Uniquely, Lhx4 mutants exhibit reduced cyclin D1 expression and have auxiliary pouch-like structures. We show evidence for indirect and direct effects of LHX4 on p21 expression in αT3-1 pituitary cells. In summary, Lhx4 is necessary for efficient pituitary progenitor cell proliferation and restriction of p21 expression.

Protein kinase D1 drives pancreatic acinar cell reprogramming and progression to intraepithelial neoplasia

The transdifferentiation of pancreatic acinar cells to a ductal phenotype (acinar-to-ductal metaplasia, ADM) occurs after injury or inflammation of the pancreas and is a reversible process. However, in the presence of activating Kras mutations or persistent epidermal growth factor receptor (EGF-R) signalling, cells that underwent ADM can progress to pancreatic intraepithelial neoplasia (PanIN) and eventually pancreatic cancer. In transgenic animal models, ADM and PanINs are initiated by high-affinity ligands for EGF-R or activating Kras mutations, but the underlying signalling mechanisms are not well understood. Here, using a conditional knockout approach, we show that protein kinase D1 (PKD1) is sufficient to drive the reprogramming process to a ductal phenotype and progression to PanINs. Moreover, using 3D explant culture of primary pancreatic acinar cells, we show that PKD1 acts downstream of TGFα and Kras, to mediate formation of ductal structures through activation of the Notch pathway.

Pancreas divisum: a common developmental variant that deserves attention in preclinical medical education

Clinical literature indicates that pancreas divisum (PD) is present in 3-22% of the population and may be associated with an increased risk of pancreatitis. PD is a developmental variant wherein the duct systems derived from the dorsal and ventral pancreatic buds are not fused. Hence secretions from the head, neck, body, and tail, which develop from the dorsal bud, must pass through the minor duodenal papilla. The smaller uncinate process, derived from the ventral bud, drains through the major duodenal papilla. The purpose of this study was: (1) to do a cadaveric dissection to confirm whether PD is common in donors who had not been selected because they had pancreatitis and (2) to determine the frequency of PD descriptions in anatomy, embryology, pathology, and surgery books in our libraries. For our anatomical study, pancreata of eight human donors were dissected. Dye was injected into the ducts so that any communications between main and accessory ducts could be easily located. For our literature review, 22 anatomy, 14 embryology, 11 pathology, and 26 surgery books were examined for mention of PD. PD was unambiguously identified in two donor cadavers. However, only 14% of the anatomy plus embryology books compared to 70% of the surgery plus pathology books describe PD. Cadaveric dissection confirms that PD is indeed prevalent. The prevalence of PD with its increased risk of pancreatitis merits inclusion of this topic in textbooks of anatomy and embryology.

The role of pancreatic and duodenal homeobox 1 as a therapeutic target in pancreatic cancer

INTRODUCTION

Pancreatic cancer is one of the most lethal cancer types known with no successful clinical therapy available and a 5-year survival rate of < 5%. Demographic calculations predict pancreatic cancer to be the second-leading cause of cancer-related deaths by 2030. Hence, the identification of novel drug targets and the subsequent development of novel therapeutic strategies are of utmost importance.

AREAS COVERED

In this review, the authors describe the role of the transcription factor pancreatic and duodenal homeobox 1 (Pdx1) in pancreatic organ development and pancreatic cancer. Published data suggest that Pdx1 possesses oncogenic traits fostering cell proliferation, inhibition of apoptosis and increased cell invasion. Resulting from these findings, the authors discuss the potential use of Pdx1 as an anticancer drug target.

EXPERT OPINION

In summary, Pdx1 should be considered as an interesting potential molecular target in future therapeutic approaches. Although no specific therapies exploiting Pdx1 are available at the moment and more preclinical data has to be accumulated, several putative applications in the areas of cancer diagnostics and therapy are conceivable.

Macrophage-secreted cytokines drive pancreatic acinar-to-ductal metaplasia through NF-κB and MMPs

In response to inflammation, pancreatic acinar cells can undergo acinar-to-ductal metaplasia (ADM), a reprogramming event that induces transdifferentiation to a ductlike phenotype and, in the context of additional oncogenic stimulation, contributes to development of pancreatic cancer. The signaling mechanisms underlying pancreatitis-inducing ADM are largely undefined. Our results provide evidence that macrophages infiltrating the pancreas drive this transdifferentiation process. We identify the macrophage-secreted inflammatory cytokines RANTES and tumor necrosis factor α (TNF) as mediators of such signaling. Both RANTES and TNF induce ADM through activation of nuclear factor κB and its target genes involved in regulating survival, proliferation, and degradation of extracellular matrix. In particular, we identify matrix metalloproteinases (MMPs) as targets that drive ADM and provide in vivo data suggesting that MMP inhibitors may be efficiently applied to block pancreatitis-induced ADM in therapy.

Notch 1 tumor expression is lacking in highly proliferative pancreatic neuroendocrine tumors

To date, very little is known about the development of benign organic hyperinsulinism and its metastatic potential. Typical morphologic, biochemical, or genetic differentiations for benign or malign tumor course of insulinomas do not exist. As signaling pathways may affect pancreatic cancer development and the maintenance of the neoplastic phenotype, the purpose of this study was to examine the role of Notch1 expression in organic hyperinsulinism. We examined 32 well-differentiated pancreatic endocrine tumors (wd PET); 11 wd PET of unknown behavior (wd PET ub); and 15 wd pancreatic endocrine cancer (wd PEC) for Notch1 expression by immunohistochemistry. Demographic data, clinical data, and follow-up of all patients were analyzed. Islets of the Langerhans show the strongest Notch1 staining in nearly 90 %. Positive Notch1 staining was absent in the acinar of the pancreas. In patients with a wd PET more than every second tumor (56.3 %/n = 18/32) demonstrated a negative Notch1 staining. The other 14 patients were positive for Notch1. Tumors of unknown behavior (wd PET ub) and malignant insulinomas had no signs of Notch expression in contrast to benign insulinomas. Considering the clinical and histomorphological tumor behavior, no correlation between Notch1 expression and clinical data was found. The missing Notch expression in the malignant tumor course might be used as a potential predictive marker, but further studies are needed to investigate the underlying molecular mechanism.

Translating discovery in zebrafish pancreatic development to human pancreatic cancer: biomarkers, targets, pathogenesis, and therapeutics

Abstract Experimental studies in the zebrafish have greatly facilitated understanding of genetic regulation of the early developmental events in the pancreas. Various approaches using forward and reverse genetics, chemical genetics, and transgenesis in zebrafish have demonstrated generally conserved regulatory roles of mammalian genes and discovered novel genetic pathways in exocrine pancreatic development. Accumulating evidence has supported the use of zebrafish as a model of human malignant diseases, including pancreatic cancer. Studies have shown that the genetic regulators of exocrine pancreatic development in zebrafish can be translated into potential clinical biomarkers and therapeutic targets in human pancreatic adenocarcinoma. Transgenic zebrafish expressing oncogenic K-ras and zebrafish tumor xenograft model have emerged as valuable tools for dissecting the pathogenetic mechanisms of pancreatic cancer and for drug discovery and toxicology. Future analysis of the pancreas in zebrafish will continue to advance understanding of the genetic regulation and biological mechanisms during organogenesis. Results of those studies are expected to provide new insights into how aberrant developmental pathways contribute to formation and growth of pancreatic neoplasia, and hopefully generate valid biomarkers and targets as well as effective and safe therapeutics in pancreatic cancer.

Topologically heterogeneous beta cell adaptation in response to high-fat diet in mice

Aims

Beta cells adapt to an increased insulin demand by enhancing insulin secretion via increased beta cell function and/or increased beta cell number. While morphological and functional heterogeneity between individual islets exists, it is unknown whether regional differences in beta cell adaptation occur. Therefore we investigated beta cell adaptation throughout the pancreas in a model of high-fat diet (HFD)-induced insulin resistance in mice.

Methods

C57BL/6J mice were fed a HFD to induce insulin resistance, or control diet for 6 weeks. The pancreas was divided in a duodenal (DR), gastric (GR) and splenic (SR) region and taken for either histology or islet isolation. The capacity of untreated islets from the three regions to adapt in an extrapancreatic location was assessed by transplantation under the kidney capsule of streptozotocin-treated mice.

Results

SR islets showed 70% increased beta cell proliferation after HFD, whereas no significant increase was found in DR and GR islets. Furthermore, isolated SR islets showed twofold enhanced glucose-induced insulin secretion after HFD, as compared with DR and GR islets. In contrast, transplantation of islets isolated from the three regions to an extrapancreatic location in diabetic mice led to a similar decrease in hyperglycemia and no difference in beta cell proliferation.

Conclusions

HFD-induced insulin resistance leads to topologically heterogeneous beta cell adaptation and is most prominent in the splenic region of the pancreas. This topological heterogeneity in beta cell adaptation appears to result from extrinsic factors present in the islet microenvironment.

Physiologie und Embryologie des Pankreas

Das Pankreas ist sowohl ein exokrines wie auch ein endokrines Organ (Tab. 21.1). Ihm kommt die zentrale Rolle in der Aufschließung der Nahrungsbestandteile sowie in der Regulation des Blutzuckerspiegels zu.

Pancreas-specific deletion of Prox1 affects development and disrupts homeostasis of the exocrine pancreas

BACKGROUND & AIMS

The exocrine portion of the pancreas functions in digestion and preserves pancreatic homeostasis. Learning how this tissue forms during embryogenesis could improve our understanding of human pancreatic diseases. Expression of the homeobox gene Prox1 in the exocrine pancreas changes throughout development in mice. We investigated the role of Prox1 in development of the exocrine pancreas in mice.

METHODS

Mice with pancreas-specific deletion of Prox1 (Prox1(ΔPanc)) were generated and their pancreatic tissues were analyzed using immunohistochemistry, transmission electron microscopy, histologic techniques, quantitative real-time polymerase chain reaction, immunoblotting, and morphometric analysis.

RESULTS

Loss of Prox1 from the pancreas led to multiple exocrine alterations, most notably premature acinar cell differentiation, increased ductal cell proliferation, altered duct morphogenesis, and imbalanced expression of claudin proteins. Prox1(ΔPanc) mice also had some minor alterations in islet cells, but beta-cell development was not affected. The exocrine congenital defects of Prox1(ΔPanc) pancreata appeared to initiate a gradual process of deterioration that resulted in extensive loss of acinar cells, lipomatosis, and damage to ductal tissue in adult mice.

CONCLUSIONS

Pancreas-specific deletion of Prox1 causes premature differentiation of acinar cells and poor elongation of epithelial branches; these defects indicate that Prox1 controls the expansion of tip progenitors in the early developing pancreas. During later stages of embryogenesis, Prox1 appears to regulate duct cell proliferation and morphogenesis. These findings identify Prox1 as an important regulator of pancreatic exocrine development.

Dorsal agenesis of the pancreas - a rare cause of abdominal pain and insulin-dependent diabetes

Dorsal agenesis of the pancreas is a rare congenital disorder. We report a case of a 65-year-old man with mild abdominal pain and insulin-dependent diabetes mellitus. Computed tomography (CT) of the abdomen showed a short pancreas with no pancreatic tissue ventral to the splenic vein. Magnetic resonance cholangiopancreatography (MRCP) visualized the absence of a dorsal duct system and confirmed the suspicion of complete agenesis of the dorsal pancreas. Endoscopic ultrasound (EUS) was also performed to rule out pancreatic malignancy.

Oncogenic Kras is required for both the initiation and maintenance of pancreatic cancer in mice

Pancreatic cancer is almost invariably associated with mutations in the KRAS gene, most commonly KRASG12D, that result in a dominant-active form of the KRAS GTPase. However, how KRAS mutations promote pancreatic carcinogenesis is not fully understood, and whether oncogenic KRAS is required for the maintenance of pancreatic cancer has not been established. To address these questions, we generated two mouse models of pancreatic tumorigenesis: mice transgenic for inducible KrasG12D, which allows for inducible, pancreas-specific, and reversible expression of the oncogenic KrasG12D, with or without inactivation of one allele of the tumor suppressor gene p53. Here, we report that, early in tumorigenesis, induction of oncogenic KrasG12D reversibly altered normal epithelial differentiation following tissue damage, leading to precancerous lesions. Inactivation of KrasG12D in established precursor lesions and during progression to cancer led to regression of the lesions, indicating that KrasG12D was required for tumor cell survival. Strikingly, during all stages of carcinogenesis, KrasG12D upregulated Hedgehog signaling, inflammatory pathways, and several pathways known to mediate paracrine interactions between epithelial cells and their surrounding microenvironment, thus promoting formation and maintenance of the fibroinflammatory stroma that plays a pivotal role in pancreatic cancer. Our data establish that epithelial KrasG12D influences multiple cell types to drive pancreatic tumorigenesis and is essential for tumor maintenance. They also strongly support the notion that inhibiting KrasG12D, or its downstream effectors, could provide a new approach for the treatment of pancreatic cancer.

Pancreatic ductal cells in development, regeneration, and neoplasia

The pancreas is a complex organ comprised of three critical cell lineages: islet (endocrine), acinar, and ductal. This review will focus upon recent insights and advances in the biology of pancreatic ductal cells. In particular, emphasis will be placed upon the regulation of ductal cells by specific transcriptional factors during development as well as the underpinnings of acinar-ductal metaplasia as an important adaptive response during injury and regeneration. We also address the potential contributions of ductal cells to neoplastic transformation, specifically in pancreatic ductal adenocarcinoma.

Pancreatic ductal cells in development, regeneration, and neoplasia

The pancreas is a complex organ comprised of three critical cell lineages: islet (endocrine), acinar, and ductal. This review will focus upon recent insights and advances in the biology of pancreatic ductal cells. In particular, emphasis will be placed upon the regulation of ductal cells by specific transcriptional factors during development as well as the underpinnings of acinar-ductal metaplasia as an important adaptive response during injury and regeneration. We also address the potential contributions of ductal cells to neoplastic transformation, specifically in pancreatic ductal adenocarcinoma.

Hormonally defined pancreatic and duodenal neuroendocrine tumors differ in their transcription factor signatures: expression of ISL1, PDX1, NGN3, and CDX2

We recently identified the transcription factor (TF) islet 1 gene product (ISL1) as a marker for well-differentiated pancreatic neuroendocrine tumors (P-NETs). In order to better understand the expression of the four TFs, ISL1, pancreatico-duodenal homeobox 1 gene product (PDX1), neurogenin 3 gene product (NGN3), and CDX-2 homeobox gene product (CDX2), that mainly govern the development and differentiation of the pancreas and duodenum, we studied their expression in hormonally defined P-NETs and duodenal (D-) NETs. Thirty-six P-NETs and 14 D-NETs were immunostained with antibodies against the four pancreatic hormones, gastrin, serotonin, calcitonin, ISL1, PDX1, NGN3, and CDX2. The TF expression pattern of each case was correlated with the tumor's hormonal profile. Insulin-positive NETs expressed only ISL1 (10/10) and PDX1 (9/10). Glucagon-positive tumors expressed ISL1 (7/7) and were almost negative for the other TFs. Gastrin-positive NETs, whether of duodenal or pancreatic origin, frequently expressed PDX1 (17/18), ISL1 (14/18), and NGN3 (14/18). CDX2 was mainly found in the gastrin-positive P-NETs (5/8) and rarely in the D-NETs (1/10). Somatostatin-positive NETs, whether duodenal or pancreatic in origin, expressed ISL1 (9/9), PDX1 (3/9), and NGN3 (3/9). The remaining tumors showed labeling for ISL1 in addition to NGN3. There was no association between a particular TF pattern and NET features such as grade, size, location, presence of metastases, and functional activity. We conclude from our data that there is a correlation between TF expression patterns and certain hormonally defined P-NET and D-NET types, suggesting that most of the tumor types originate from embryologically determined precursor cells. The observed TF signatures do not allow us to distinguish P-NETs from D-NETs.