β-Catenin Activation in Hepatocellular Cancer: Implications in Biology and Therapy

Hepatocellular cancer (HCC), the most common primary liver tumor, has been gradually growing in incidence globally. The whole-genome and whole-exome sequencing of HCC has led to an improved understanding of the molecular drivers of this tumor type. Activation of the Wnt signaling pathway, mostly due to stabilizing missense mutations in its downstream effector β-catenin (encoded by CTNNB1) or loss-of-function mutations in AXIN1 (the gene which encodes for Axin-1, an essential protein for β-catenin degradation), are seen in a major subset of HCC. Because of the important role of β-catenin in liver pathobiology, its role in HCC has been extensively investigated. In fact, CTNNB1 mutations have been shown to have a trunk role. β-Catenin has been shown to play an important role in regulating tumor cell proliferation and survival and in tumor angiogenesis, due to a host of target genes regulated by the β-catenin transactivation of its transcriptional factor TCF. Proof-of-concept preclinical studies have shown β-catenin to be a highly relevant therapeutic target in CTNNB1-mutated HCCs. More recently, studies have revealed a unique role of β-catenin activation in regulating both tumor metabolism as well as the tumor immune microenvironment. Both these roles have notable implications for the development of novel therapies for HCC. Thus, β-catenin has a pertinent role in driving HCC development and maintenance of this tumor-type, and could be a highly relevant therapeutic target in a subset of HCC cases

Enhanced Neutrophil Extracellular Trap Formation in Acute Pancreatitis Contributes to Disease Severity and Is Reduced by Chloroquine

Background: Neutrophil extracellular traps (NETs) are generated when activated neutrophils, driven by PAD4, release their DNA, histones, HMGB1, and other intracellular granule components. NETs play a role in acute pancreatitis, worsening pancreatic inflammation, and promoting pancreatic duct obstruction. The autophagy inhibitor chloroquine (CQ) inhibits NET formation; therefore, we investigated the impact of CQ mediated NET inhibition in murine models of pancreatitis and human correlative studies. Methods: L-arginine and choline deficient ethionine supplemented (CDE) diet models of acute pancreatitis were studied in wild type and PAD4−/− mice, incapable of forming NETs. Isolated neutrophils were stimulated to induce NET formation and visualized with fluorescence microscopy. CQ treatment (0.5 mg/ml PO) was initiated after induction of pancreatitis. Biomarkers of NET formation, including cell-free DNA, citrullinated histone H3 (CitH3), and MPO-DNA conjugates were measured in murine serum and correlative human patient serum samples. Results: We first confirmed the role of NETs in the pathophysiology of acute pancreatitis by demonstrating that PAD4−/− mice had decreased pancreatitis severity and improved survival compared to wild-type controls. Furthermore, patients with severe acute pancreatitis had elevated levels of cell-free DNA and MPO-DNA conjugates, consistent with NET formation. Neutrophils from mice with pancreatitis were more prone to NET formation and CQ decreased this propensity to form NETs. CQ significantly reduced serum cell-free DNA and citrullinated histone H3 in murine models of pancreatitis, increasing survival in both models. Conclusions: Inhibition of NETs with CQ decreases the severity of acute pancreatitis and improves survival. Translating these findings into clinical trials of acute pancreatitis is warranted

Paradoxical Role of AT-rich Interactive Domain 1A in Restraining Pancreatic Carcinogenesis

Background & Aims: ARID1A is postulated to be a tumor suppressor gene owing to loss-of-function mutations in human pancreatic ductal adenocarcinomas (PDAC). However, its role in pancreatic pathogenesis is not clear despite recent studies using genetically engineered mouse (GEM) models. We aimed at further understanding of its direct functional role in PDAC, using a combination of GEM model and PDAC cell lines. Methods: Pancreas-specific mutant Arid1a-driven GEM model (Ptf1a-Cre; KrasG12D; Arid1af/f or “KAC”) was generated by crossing Ptf1a-Cre; KrasG12D (“KC”) mice with Arid1af/f mice and characterized histologically with timed necropsies. Arid1a was also deleted using CRISPR-Cas9 system in established human and murine PDAC cell lines to study the immediate effects of Arid1a loss in isogenic models. Cell lines with or without Arid1a expression were developed from respective autochthonous PDAC GEM models, compared functionally using various culture assays, and subjected to RNA-sequencing for comparative gene expression analysis. DNA damage repair was analyzed in cultured cells using immunofluorescence and COMET assay. Results: Retention of Arid1a is critical for early progression of mutant Kras-driven pre-malignant lesions into PDAC, as evident by lower Ki-67 and higher apoptosis staining in “KAC” as compared to “KC” mice. Enforced deletion of Arid1a in established PDAC cell lines caused suppression of cellular growth and migration, accompanied by compromised DNA damage repair. Despite early development of relatively indolent cystic precursor lesions called intraductal papillary mucinous neoplasms (IPMNs), a subset of “KAC” mice developed aggressive PDAC in later ages. PDAC cells obtained from older autochthonous “KAC” mice revealed various compensatory (“escaper”) mechanisms to overcome the growth suppressive effects of Arid1a loss. Conclusions: Arid1a is an essential survival gene whose loss impairs cellular growth, and thus, its expression is critical during early stages of pancreatic tumorigenesis in mouse models. In tumors that arise in the setting of ARID1A loss, a multitude of “escaper” mechanisms drive progression

Enhanced Neutrophil Extracellular Trap Formation in Acute Pancreatitis Contributes to Disease Severity and Is Reduced by Chloroquine

Background: Neutrophil extracellular traps (NETs) are generated when activated neutrophils, driven by PAD4, release their DNA, histones, HMGB1, and other intracellular granule components. NETs play a role in acute pancreatitis, worsening pancreatic inflammation, and promoting pancreatic duct obstruction. The autophagy inhibitor chloroquine (CQ) inhibits NET formation; therefore, we investigated the impact of CQ mediated NET inhibition in murine models of pancreatitis and human correlative studies.Methods: L-arginine and choline deficient ethionine supplemented (CDE) diet models of acute pancreatitis were studied in wild type and PAD4−/− mice, incapable of forming NETs. Isolated neutrophils were stimulated to induce NET formation and visualized with fluorescence microscopy. CQ treatment (0.5 mg/ml PO) was initiated after induction of pancreatitis. Biomarkers of NET formation, including cell-free DNA, citrullinated histone H3 (CitH3), and MPO-DNA conjugates were measured in murine serum and correlative human patient serum samples.Results: We first confirmed the role of NETs in the pathophysiology of acute pancreatitis by demonstrating that PAD4−/− mice had decreased pancreatitis severity and improved survival compared to wild-type controls. Furthermore, patients with severe acute pancreatitis had elevated levels of cell-free DNA and MPO-DNA conjugates, consistent with NET formation. Neutrophils from mice with pancreatitis were more prone to NET formation and CQ decreased this propensity to form NETs. CQ significantly reduced serum cell-free DNA and citrullinated histone H3 in murine models of pancreatitis, increasing survival in both models.Conclusions: Inhibition of NETs with CQ decreases the severity of acute pancreatitis and improves survival. Translating these findings into clinical trials of acute pancreatitis is warranted

Endoscopic Ultrasound and Related Technologies for the Diagnosis and Treatment of Pancreatic Disease - Research Gaps and Opportunities: Summary of a National Institute of Diabetes and Digestive and Kidney Diseases Workshop

A workshop was sponsored by the National Institute of Diabetes and Digestive and Kidney Diseases to address the research gaps and opportunities in pancreatic endoscopic ultrasound (EUS). The event occurred on July 26, 2017 in 4 sessions: (1) benign pancreatic diseases, (2) high-risk pancreatic diseases, (3) diagnostic and therapeutics, and (4) new technologies. The current state of knowledge was reviewed, with identification of numerous gaps in knowledge and research needs. Common themes included the need for large multicenter consortia of various pancreatic diseases to facilitate meaningful research of these entities; to standardize EUS features of different pancreatic disorders, the technique of sampling pancreatic lesions, and the performance of various therapeutic EUS procedures; and to identify high-risk disease early at the cellular level before macroscopic disease develops. The need for specialized tools and accessories to enable the safe and effective performance of therapeutic EUS procedures also was discussed

Integrated genomic characterization of pancreatic ductal adenocarcinoma

We performed integrated genomic, transcriptomic, and proteomic profiling of 150 pancreatic ductal adenocarcinoma (PDAC) specimens, including samples with characteristic low neoplastic cellularity. Deep whole-exome sequencing revealed recurrent somatic mutations in KRAS, TP53, CDKN2A, SMAD4, RNF43, ARID1A, TGFβR2, GNAS, RREB1, and PBRM1. KRAS wild-type tumors harbored alterations in other oncogenic drivers, including GNAS, BRAF, CTNNB1, and additional RAS pathway genes. A subset of tumors harbored multiple KRAS mutations, with some showing evidence of biallelic mutations. Protein profiling identified a favorable prognosis subset with low epithelial-mesenchymal transition and high MTOR pathway scores. Associations of non-coding RNAs with tumor-specific mRNA subtypes were also identified. Our integrated multi-platform analysis reveals a complex molecular landscape of PDAC and provides a roadmap for precision medicine

Selection subtraction approach (SSA).

Selection subtraction approach (SSA)

Colorectal Granular Cell Tumor: A Clinicopathologic Study of 26 Cases

Granular cell tumor (GCT) is commonly located in the subcutaneous tissue and oral cavity, and uncommon in the gastrointestinal tract, in which the majority arises in the esophagus with over-representation in African Americans (AA). However, experience with GCTs of the colorectum is quite limited. We report the clinicopathologic features of 1 of the largest series to date of colorectal GCTs. We reviewed the clinical features of 26 colorectal GCTs seen at our institution between the years 1995 to 2009, which included 24 biopsies, 1 low anterior resection, and 1 colectomy. Review of the clinical features of all 26 cases from 24 patients identified an equal gender distribution (12 males and 12 females), with patients ranging in age from 31 to 60 years (mean, 49.8 y; median, 51.5 y) with a modest White predominance (15/24, 63%; our overall patient population is 67% White). The majority of colorectal GCT involved the right colon (19/26, 73%) ranging in size from 0.2 to 1.8 cm (mean 0.6 cm). Most neoplasms were encountered on routine colonoscopy (14/24, 64%), however 3 patients presented with hematochezia, 3 with changing bowel habits, 2 with Crohn disease, 1 with diverticular disease, and 1 with appendicitis. Of the 20 cases available for histologic review, the tumors were noted to either be infiltrative (12/20, 60%) or marginated (8/20, 40%) involving either the mucosa (7/20, 35%), submucosa (10/20, 50%), or both (3/20, 15%). The microscopic features were similar to those of GCTs found elsewhere, but many of the neoplasms differed by displaying nuclear pleomorphism (8/20, 40%), lymphoid cuffs (9/20, 45%), and focal calcification (7/20, 35%). Some had reactive mucosal surface changes (7/20, 35%), including 1 initially misdiagnosed as a tubular adenoma. Neither mitoses nor necrosis were identified. On immunochemistry, 18 of the neoplasms were stained for S-100 and all cases showed positive staining. Followup information was available for 19 patients (19/24, 79%) with 2 documented occurrences of regrowth at the prior cecal biopsy site owing to incomplete excision, but no metastases. Although infrequently found in the colorectum, colorectal GCT typically presents incidentally on routine colonoscopy and involves the right colon; it is not over-represented in AA patients. GCTs can have both an infiltrative or marginated growth pattern with a subset displaying nuclear pleomorphism, a lymphoid cuff, focal calcification, and reactive mucosal surface changes, which in our experience, may lead to misdiagnosis on colorectal mucosal biopsies. Although GCTs were benign tumors in this series, if incompletely excised regrowth of the lesion may occur and therefore, follow-up may be warranted

Gastrointestinal Tract Langerhans Cell Histiocytosis: A Clinicopathologic Study of 12 Patients

Gastrointestinal (GI) tract involvement by Langerhans cell histiocytosis (LCH) is a rare condition. It is typically noted in male patients with systemic disease and is associated with both poor prognosis and high morbidity. The incidence peaks in childhood. However, a limited number of cases have been reported in adults. To further characterize this disease process, we collected 24 cases of GI tract LCH from 12 patients. The patients included 2 children (4 mo and 2.3 y) and 10 adults (40 to 77 y; mean, 58.4 y), with a female predominance (9 of 12, 75%). Both children presented with failure to thrive, bloody diarrhea, and anemia. In contrast, 5 of 10 (50%) adults were asymptomatic and the rest had unrelated symptoms. Endoscopically, the pediatric patients showed the involvement of the duodenum and multiple colonic sites. However, 8 of 10 (80%) adults presented with a solitary polyp, primarily involving the colorectum (7 of 8, 88%). The lesions ranged in size from 0.1 to 0.8 cm (mean, 0.4 cm), and were predominantly intramucosal (18 of 24, 75%) with either a marginated (14 of 24, 58%) or infiltrative (10 of 24, 42%) growth pattern. Microscopic features were similar to those of LCH found elsewhere, although some cases differed by showing prominent lymphocytes (12 of 24, 50%) rather than eosinophils and large nucleoli (2 of 24, 8%). Reactive overlying mucosal and entrapped epithelial changes (10 of 24, 42%), mucosal ulceration (3 of 24, 13%), focal necrosis (1 of 24), and multinucleated giant cells (1 of 24) were also identified. Mitotic figures were absent. On immunohistochemistry, all lesions expressed the S-100 protein and CD1a. Follow-up information was available for 11 (92%) patients ranging from 2 months to 5.3 years (mean, 1.8 y). One pediatric patient was lost to follow-up. However, the other patient developed multisystem disease and died 1 year after the initial diagnosis. Two adult patients developed cutaneous disease, 2 months and 2 years after the initial diagnosis, 1 of whom had multifocal colonic disease. On the basis of this study, GI tract LCH lesions present in both children and adults with a female predominance. Consistent with earlier reports, pediatric cases are associated with systemic disease and poor prognosis. However, in adults, LCH is typically encountered as an incidental, solitary polyp. Rare cases of systemic disease may occur and, therefore, close follow-up may be warranted