Abstract B08: The role of periostin in pancreatic carcinogenesis and metastatic spread

Abstract

Abstract Background: Excessive desmoplasia is a typical feature of pancreatic ductal adenocarcinoma (PDAC) and is highly associated with an aggressive tumor phenotype. The main cell population contributing to the stromal response consists of pancreatic stellate cells (PSCs). Periostin, an extracellular matrix protein (ECM), produced by activated PSCs has been shown to have anti-apoptotic and growth-stimulatory effects on pancreatic tumor cells as well as the ability to create a metastatic niche in the secondary target organ. The main signaling route by which periostin mediates its effects is the integrin signaling pathway. Through binding to different integrin subunits the focal adhesion kinase (FAK) gets phosphorylated and downstream signaling pathways such as RAS/ERK/MEK become additionally activated. Aim: Analyzing the function of periostin in early pancreatic carcinogenesis as well as metastatic spread. Methods: A conditional tumor mouse model, expressing oncogenic KrasG12D under the control of a pancreas specific Ptf1a promoter was crossbred with Postn global knockout mice (p48Cre/+;LSL-KrasG12D/+;Postn-/-) and early tumor development was analyzed at two, three and six months of age. In a second approach, a tumor-promoting inflammatory stromal reaction was induced by cerulein injections in p48Cre/+;LSL-KrasG12D/+ mice whereby one group of mice was additionally treated with a daily dose (30mg/kg) of FAK inhibitor. All mice were sacrificed after 7 days and HE staining was performed. Thirdly, to study metastasis formation, murine pancreatic tumor cells were injected into the tail vein of wild type, Postn+/- and Postn-/- mice. After 6 weeks target organs were collected for subsequent analyses. Results: In the early phases, p48Cre/+;LSL-KrasG12D/+;Postn-/- mice displayed less PanIN lesions, fewer atypical ductal structures and reduced proliferating cells. The inhibition of FAK-signaling blocked pancreatic tumorigenesis and absence of periostin abrogated metastatic spread. Conclusion: Periostin produced by the pancreatic stellate cell is necessary both for early carcinogenesis and metastatic spread. The effects of periostin can be antagonized by blocking its downstream pathway using FAK inhibitors. Citation Format: Simone Hausmann, Ivonne Regel, Anna Federlein, Pawel K. Mazur, Katja Steiger, Christoph W. Michalski, Mert Erkan, Jörg Kleeff. The role of periostin in pancreatic carcinogenesis and metastatic spread. [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 B08.