Targeting Pancreatic Ductal Adenocarcinoma Acidic Microenvironment

Pancreatic ductal adenocarcinoma (PDAC) is the fourth leading cause of cancer death in the USA, accounting for ~40,000 deaths annually. The dismal prognosis for PDAC is largely due to its late diagnosis. Currently, the most sensitive diagnosis of PDAC requires invasive procedures, such as endoscopic ultrasonography, which has inherent risks and accuracy that is highly operator dependent. Here we took advantage of a general characteristic of solid tumors, the acidic microenvironment that is generated as a by-product of metabolism, to develop a novel approach of using pH (Low) Insertion Peptides (pHLIPs) for imaging of PDAC. We show that fluorescently labeled pHLIPs can localize and specifically detect PDAC in human xenografts as well as PDAC and PanIN lesions in genetically engineered mouse models. This novel approach may improve detection, differential diagnosis and staging of PDAC

Detection of pancreatic cancer tumours and precursor lesions by cathepsin E activity in mouse models.

ABSTRACT Background and Aims Pancreatic ductal adenocarcinoma (PDAC) is the fourth leading cause of cancer death in the USA. Surgical resection is the only effective treatment; however, only 20% of patients are candidates for surgery. The ability to detect early PDAC would increase the availability of surgery and improve patient survival. This study assessed the feasibility of using the enzymatic activity of cathepsin E (Cath E), a protease highly and specifically expressed in PDAC, as a novel biomarker for the detection of pancreas-bearing pancreatic intraepithelial neoplasia (PanIN) lesions and PDAC. Methods Pancreas from normal, chronic pancreatitis and PDAC patients was assessed for Cath E expression by quantitative real-time PCR and immunohistochemistry. Human PDAC xenografts and genetically engineered mouse models (GEMM) of PDAC were injected with a Cath E activity selective fluorescent probe and imaged using an optical imaging system. Results The specificity of Cath E expression in PDAC patients and GEMM of pancreatic cancer was confirmed by quantitative real-time PCR and immunohistochemistry. The novel probe for Cath E activity specifically detected PDAC in both human xenografts and GEMM in vivo. The Cath E sensitive probe was also able to detect pancreas with PanIN lesions in GEMM before tumour formation. Conclusions The elevated Cath E expression in PanIN and pancreatic tumours allowed in-vivo detection of human PDAC xenografts and imaging of pancreas with PanIN and PDAC tumours in GEMM. Our results support the usefulness of Cath E activity as a potential molecular target for PDAC and early detection imaging. Despite great efforts to help patients with pancreatic ductal adenocarcinoma (PDAC) in the past few years, this disease remains devastating with the worst outcome of all major cancers. In the USA, PDAC ranks 10th in terms of incidence, but for both men and women, it is fourth in terms of cancer deaths. Although many molecular biomarker candidates of PDAC have been identified, 3 biomarkers with the necessary sensitivity and specificity for early detection are still lacking. 4e6 The most widely utilised blood-based biomarker is CA 19-9, which is not expressed in all patients, is not highly specific as it is elevated in other gastrointestinal cancers, and is not useful for the detection of early disease. 7 8 Furthermore, CA 19-9 levels do not provide information about the localisation of the disease nor the existence of metastases. The most sensitive diagnosis of PDAC currently requires invasive imaging procedures such as endoscopic ultrasonography, which Significance of this study What is already known about this subject? < No highly specific and sensitive biomarkers are clinically available for the detection of PDAC at an early stage. < Cath E is highly overexpressed in many cancers including PDAC. < A Cath E selective peptide was recently identified that specifically detects its enzymatic activity. What are the new findings? < We demonstrate that the elevated levels of Cath E expression in early pancreatic cancer lesions and pancreatic tumours could be exploited for PDAC detection. < We illustrate that the detection and localisation of PDAC in mouse xenografts and GEMM was possible utilising the outstanding specificity of a novel Cath E-activatable imaging probe. How might it impact on clinical practice in the foreseeable future? < The ability to detect and visualise pancreatic tumours and PanIN in PDAC by virtue of Cath E activity sensitive probes in preclinical mouse models suggests that modifications of this approach will be useful for the early detection and management of this deadly cancer in patients. < The specificity of Cath E activity for PDAC suggests that this enzymatic activity will be useful in the future for the development of novel therapeutics or theranostics. Cruz-Monserrate Z, Abd-Elgaliel WR, Grote T, et al. Gut (2011)

Diabetes Mellitus and Obesity as Risk Factors for Pancreatic Cancer

Pancreatic ductal adenocarcinoma (PDAC) is among the deadliest types of cancer. The worldwide estimates of its incidence and mortality in the general population are eight cases per 100,000 person-years and seven deaths per 100,000 person-years, and they are significantly higher in the United States than in the rest of the world. The incidence of this disease in the United States is more than 50,000 new cases in 2017. Indeed, total deaths due to PDAC are projected to increase dramatically to become the second leading cause of cancer-related deaths before 2030. Considering the failure to date to efficiently treat existing PDAC, increased effort should be undertaken to prevent this disease. A better understanding of the risk factors leading to PDAC development is of utmost importance to identify and formulate preventive strategies. Large epidemiologic and cohort studies have identified risk factors for the development of PDAC, including obesity and type 2 diabetes mellitus. This review highlights the current knowledge of obesity and type 2 diabetes as risk factors for PDAC development and progression, their interplay and underlying mechanisms, and the relation to diet. Research gaps and opportunities to address this deadly disease are also outlined

Type 3c (pancreatogenic) diabetes mellitus secondary to chronic pancreatitis and pancreatic cancer

Diabetes mellitus is a group of diseases defined by persistent hyperglycaemia. Type 2 diabetes, the most prevalent form, is characterised initially by impaired insulin sensitivity and subsequently by an inadequate compensatory insulin response. Diabetes can also develop as a direct consequence of other diseases, including diseases of the exocrine pancreas. Historically, diabetes due to diseases of the exocrine pancreas was described as pancreatogenic or pancreatogenous diabetes mellitus, but recent literature refers to it as type 3c diabetes. It is important to note that type 3c diabetes is not a single entity; it occurs because of a variety of exocrine pancreatic diseases with varying mechanisms of hyperglycaemia. The most commonly identified causes of type 3c diabetes are chronic pancreatitis, pancreatic ductal adenocarcinoma, haemochromatosis, cystic fibrosis, and previous pancreatic surgery. In this Review, we discuss the epidemiology, pathogenesis, and clinical relevance of type 3c diabetes secondary to chronic pancreatitis and pancreatic ductal adenocarcinoma, and highlight several important knowledge gaps

The Interface of Pancreatic Cancer With Diabetes, Obesity, and Inflammation: Research Gaps and Opportunities: Summary of a National Institute of Diabetes and Digestive and Kidney Diseases Workshop.

A workshop on "The Interface of Pancreatic Cancer with Diabetes, Obesity, and Inflammation: Research Gaps and Opportunities" was held by the National Institute of Diabetes and Digestive and Kidney Diseases on October 12, 2017. The purpose of the workshop was to explore the relationship and possible mechanisms of the increased risk of pancreatic ductal adenocarcinoma (PDAC) related to diabetes, the role of altered intracellular energy metabolism in PDAC, the mechanisms and biomarkers of diabetes caused by PDAC, the mechanisms of the increased risk of PDAC associated with obesity, and the role of inflammatory events and mediators as contributing causes of the development of PDAC. Workshop faculty reviewed the state of the current knowledge in these areas and made recommendations for future research efforts. Further knowledge is needed to elucidate the basic mechanisms contributing to the role of hyperinsulinemia, hyperglycemia, adipokines, and acute and chronic inflammatory events on the development of PDAC

SpHincterotomy for Acute Recurrent Pancreatitis Randomized Trial: Rationale, Methodology, and Potential Implications

Objectives: In patients with acute recurrent pancreatitis (ARP), pancreas divisum, and no other etiologic factors, endoscopic retrograde cholangiopancreatography (ERCP) with minor papilla endoscopic sphincterotomy (miES) is often performed to enlarge the minor papillary orifice, based on limited data. The aims of this study are to describe the rationale and methodology of a sham-controlled clinical trial designed to test the hypothesis that miES reduces the risk of acute pancreatitis. Methods: The SpHincterotomy for Acute Recurrent Pancreatitis (SHARP) trial is a multicenter, international, sham-controlled, randomized trial comparing endoscopic ultrasound + ERCP with miES vs. endoscopic ultrasound + sham for the management of ARP. A total of 234 consented patients having two or more discrete episodes of acute pancreatitis, pancreas divisum confirmed by magnetic resonance cholangiopancreatography, and no other clear etiology for acute pancreatitis will be randomized. Both cohorts will be followed for a minimum of 6 months and maximum of 48 months. Results: The trial is powered to detect a 33% risk reduction of acute pancreatitis frequency. Conclusions: The SHARP trial will determine whether ERCP with miES benefits patients with idiopathic ARP and pancreas divisum. Trial planning has informed the importance of blinded outcome assessors and long-term follow-up

Integrin α6β4 Promotes Migration, Invasion through Tiam1 Upregulation, and Subsequent Rac Activation1,2

The lethality of pancreatic adenocarcinoma stems from an elevated incidence of tumor cell invasion and metastasis that are mediated by mechanisms not yet understood. Recent studies indicate that the proinvasive integrin α6β4 is highly upregulated in pancreatic adenocarcinomas. To assess the importance of this integrin in pancreatic cancer cell migration and invasion, cell lines were screened for integrin α6β4 expression by immunoblotting and fluorescence-activated cell sorting and their ability to migrate and invade toward hepatocyte growth factor (HGF). We found that cell surface expression of the α6β4 integrin correlated with the cells' ability to migrate and invade toward HGF. When cells expressing high levels of integrin α6β4 were treated with small interfering RNA targeting α6 or β4 integrin subunits, we observed a reduction in cell migration and invasion. Furthermore, the activity of the small GTPase Rac1 was stimulated by α6β4 integrin expression and was necessary for HGF-stimulated chemotaxis. We discovered that expression of the Rac-specific nucleotide exchange factor, Tiam1 (T-lymphoma invasion and metastasis), was upregulated in cells overexpressing the integrin α6β4 and required for the elevated Rac1 activity in these cells. We conclude that the integrin α6β4 promotes the migratory and invasive phenotype of pancreatic carcinoma cells through the Tiam1-Rac1 pathway in part through the upregulation of Tiam1

Interaction of diazonamide A with tubulin

[3H]Diazonamide A ([3H]DZA), prepared from the natural product isolated from Diazona angulata, bound to tubulin in larger aberrant assembly products (>500 kDa by sizing HPLC) but not to the αβ-tubulin heterodimer. The binding reaction was rapid, but stoichiometry was low. Stoichiometry was enhanced up to 8-fold by preincubating the tubulin in the reaction mixture prior to adding the [3H]DZA. Although Mg2+ did not affect binding stoichiometry, the cation markedly increased the number of tubulin rings (diameter about 50 nm) observed by negative stain electron microscopy. Bound [3H]DZA did not dissociate from the tubulin oligomers despite extensive column chromatography but did dissociate in the presence of 8 M urea. With preincubated tubulin, a superstoichiometric amount of [3H]DZA appeared to bind to the tubulin oligomeric structures, consistent with observations that neither nonradiolabeled DZA nor DZA analogues inhibited binding of [3H]DZA to the tubulin oligomers. Only weak inhibition of binding was observed with multiple antimitotic compounds. In particular, no inhibition occurred with vinblastine, and the best inhibitors of those examined were dolastatin 10 and cryptophycin 1. We compared the aberrant assembly reaction induced by DZA to those induced by other antimitotic peptides and depsipeptides, in particular dolastatin 10, cryptophycin 1, and hemiasterlin, but the results obtained varied considerably in terms of requirements for maximal reactions, polymer morphology, and inhibitory effects observed with antimitotic compounds