Jennifer Watt

Pancreatic cancer organotypics: High throughput, preclinical models for pharmacological agent evaluation.

Pancreatic cancer carries a terrible prognosis, as the fourth most common cause of cancer death in the Western world. There is clearly a need for new therapies to treat this disease. One of the reasons no effective treatment has been developed in the past decade may in part, be explained by the diverse influences exerted by the tumour microenvironment. The tumour stroma cross-talk in pancreatic cancer can influence chemotherapy delivery and response rate. Thus, appropriate preclinical in vitro models which can bridge simple 2D in vitro cell based assays and complex in vivo models are required to understand the biology of pancreatic cancer. Here we discuss the evolution of 3D organotypic models, which recapitulare the morphological and functional features of pancreatic ductal adenocarcinoma (PDAC). Organotypic cultures are a valid high throughput preclinical in vitro model that maybe a useful tool to help establish new therapies for PDAC. A huge advantage of the organotypic model system is that any component of the model can be easily modulated in a short time-frame. This allows new therapies that can target the cancer, the stromal compartment or both to be tested in a model that mirrors the in vivo situation. A major challenge for the future is to expand the cellular composition of the organotypic model to further develop a system that mimics the PDAC environment more precisely. We discuss how this challenge is being met to increase our understanding of this terrible disease and develop novel therapies that can improve the prognosis for patients.

The desmoplastic stroma of pancreatic cancer is a barrier to immune cell infiltration

A detailed map demonstrating the spatially restricted distribution of immune cells within the desmoplastic stroma of human pancreatic tumors opens up the field of pancreatic oncoimmunology. CD8+ T cells located in the proximity of malignant lesions are associated with a survival advantage, suggesting the existence of immunoediting. Pancreatic stellate cells appear to dictate the infiltration of the juxtatumoral stroma by CD8+ T cells.

Role of laparoscopy in hepatobiliary malignancies

The many benefits of laparoscopy, including smaller incision, reduced length of hospital stay and more rapid return to normal function, have seen its popularity grow in recent years. With concurrent improvements in non-surgical cancer management the importance of accurate staging is becoming increasingly important. There are two main applications of laparoscopic surgery in managing hepato-pancreatico-biliary (HPB) malignancy: accurate staging of disease and resection. We aim to summarize the use of laparoscopy in these contexts. The role of staging laparoscopy has become routine in certain cancers, in particular T2 staged, locally advanced gastric cancer, hilar cholangiocarcinoma and non-Hodgkins lymphoma. For other cancers, in particular colorectal, laparoscopy has now become the gold standard management for resection such that there is no role for stand-alone staging laparoscopy. In HPB cancers, although staging laparoscopy may play a role, with ever improving radiology, its role remains controversial.

Abstract A56: The role of Pentraxin 3 (PTX3) in pancreatic ductal adenocarcinoma

Background: Pancreatic ductal adenocarcinoma (PDAC) is a disease with dismal prognosis and is invariably diagnosed late. Current tests used to diagnose or monitor PDAC are invasive and expensive. Tumour-supportive desmoplastic stroma, an important modulator of PDAC, is laid down by pancreatic stellate cells (PSC). All-trans Retinoic Acid (ATRA), a pleiotropic agent modulating multiple signalling pathways, renders activated stellate cells quiescent. Pentraxin 3 (PTX3) gene level expression is downregulated upon rendering stellate cells quiescent. The interaction between PTX3 and TSG-6 has been shown in other disease states to stabilise hyaluranon (HA) present in the extracellular matrix. PDAC extracellular matrix is known to be rich in HA. Methods: Human serum PTX3 levels were measured by ELISA. Twelve pancreatic cell lines, primary and immortalised pancreatic stellate cell lines were screened for PTX3 and TSG-6 expression at protein and mRNA levels. Distribution of PTX3, TSG-6 and HA in organotypic 3D cultures, transgenic mice and patient samples was determined using immunohistochemistry and immunofluorescence. Results: PDAC patients have significantly higher serum PTX3 levels (median 15.32 ng/ml, range 5.42-39.87 ng/ml, n= 43 ) compared to patients with other pancreatic diseases (median=7.09 ng/ml, range 4.45-14.01 ng/ml, n=36, 2 way anova P=0.014) and healthy individuals (median 3.72 ng/ml, range 1.97-8.82 ng/ml, n=22, 2 way anova P=0.001) ROC curve analysis ((AUC=0.946 (95%CI= 0.9-0.99, P Western blotting and immunofloursecnce demonstrate PTX3 is present maximally in stellate cells and also in some pancreatic cancer cell lines and is secreted in heavily glycosylated form. Rendering PSC quiescent reduced expression and secretion of PTX3. In the 3D organotypic culture model secreted PTX3 stains both cancer cells and PSC. However, in ATRA treated organotypics only the PSC are positive. Immunofluorescent examination reveals HA expression at the cellular membrane of PSC with no expression in cancer cells. In the organotypic model there is strong HA expression in the PSC layer. Immunohistochemistry staining of human PDAC tissues shows PTX3 to be predominantly expressed in the tumour stroma, a small proportion of patients also express PTX3 in the epithelial component of their tumours. Conclusions: PTX3 distinguishes pancreatic cancer from other diseases of the pancreas and can be tested using a simple blood test. Activated PSC produce this marker and its expression is down regulated on rendering these cells quiescent. PTX3 could be used as a marker for monitoring stromal response in stroma-targeted therapy. The interaction of PTX3 with HA in PDAC is the subject of ongoing investigation. Citation Format: Jennifer Watt, Imran Siddique, Thomas Dowe, Tatjana Crnogorac-Jurcevic, Satyajit Bhattacharya, Paola Allavena, Hemant M. Kocher. The role of Pentraxin 3 (PTX3) in pancreatic ductal adenocarcinoma. [abstract]. In: Proceedings of the AACR Special Conference on Pancreatic Cancer: Innovations in Research and Treatment; May 18-21, 2014; New Orleans, LA. Philadelphia (PA): AACR; Cancer Res 2015;75(13 Suppl):Abstract nr A56.

Role of PTX3 in pancreatic cancer

Abstract Background Pancreatic ductal adenocarcinoma (PDAC) is a disease with dismal prognosis and is invariably diagnosed late. Tests used to diagnose or monitor the disease are invasive, inaccurate, and expensive. Tumour-supportive stroma is an important feature of PDAC. All-trans retinoic acid renders activated stellate cells quiescent and thereby targets cancer and immune cells in cancer as shown by our laboratory. PTX3 gene level expression is downregulated on rendering stellate cells quiescent. We aimed to investigate the role of PTX3 in PDAC and to assess it as a marker for pancreatic cancer. Methods Serum samples from 101 patients were tested by ELISA for PTX3 expression. 53 patients with PDAC and 48 controls were studied. The control group consisted of healthy individuals and patients with other pancreatic diseases. Twelve pancreatic cell lines were screened for PTX3 expression at protein level. Primary and immortalised pancreatic stellate cell lines were also examined. Distribution of PTX3 in three-dimensional organotypic cultures and human tissues was determined by immunohistochemistry. Findings Patients with PDAC had significantly higher serum PTX3 concentrations than patients with other pancreatic diseases and healthy individuals (median 11·0 ng/mL [IQR 7·7–21·3] vs 5·6 [4·8–7·8] vs 3·2 [2·0–4·1], Kruskal-Wallis p Interpretation We found that PTX3 distinguished pancreatic cancer from other diseases of the pancreas. Activated stellate cells produced this marker and its expression was downregulated on rendering these cells quiescent. PTX3 is a stromal compartment-specific pancreatic cancer biomarker that is suitable for validation studies. Funding Barts Health NHS Trust.