Abstract 5079: Parasympathetic signaling suppresses pancreatic cancer development

Abstract

Abstract Background/Aims: The parasympathetic nervous system plays an important role in the regulation of epithelial homeostasis and has also been postulated to play a role in tumorigenesis. However, the exact role of the vagus nerve in pancreatic carcinogenesis is not well understood. Here we study the effects of muscarinic signaling on pancreatic tumorigenesis in a genetically engineered mouse model of pancreatic cancer (PDx1-Cre/KRasG12D (KC). Methods: Mice were either vagotomized at 8 weeks or treated with a cholinergic agonist. Pancreatic tissue was collected and analyzed by immunohistochemistry and RT-PCR at 20 weeks of age; cells were isolated and assayed for colony and sphere forming assays. Different human (AsPC-1, BxPC-3, Mia PaCa-2, Panc-1) and murine (K-2548 and K-8282) pancreatic cancer cell lines were subjected to cholinergic and anti-cholinergic drugs and assayed by RT-PCR, Western blot and flow cytometry. Results: In pancreatic organoid cultures derived from pancreata harboring an oncogenic KRas mutation, cholinergic agonists suppressed sphere formation significantly. Furthermore, pharmacological inhibition or genetic knockout of the muscarinic M3 receptor abolished this effect in vitro. In human and murine pancreatic cancer cells, anchorage independent growth and tumor sphere forming capacity were reduced by pretreatment with cholinergic agonists. Further evaluation revealed that parasympathetic agonists decrease the CD44+CD24+EpCAM+ proved CSC's population. Vagotomy, when performed in KC mice at 8 weeks resulted in pancreatic cancer development in 20% of the animals at 20 week of age. Treatment with the direct muscarinic agonist bethanechol caused a significant delay of PanIN progression in KC mice. Conclusions: Taken together, our findings suggest that vagal innervation has a regulatory role in pancreatic tumorigenesis via M3 receptor-mediated suppression of CSCs. Since current surgical approaches to resection of PDAC from the head of the pancreas are necessarily associated with a parasympathetic denervation of the pancreas, and thereby a loss of its suppressive effect, this fact may might partly explain the high local recurrence rate of this dismal disease. Additional treatment with cholinergic agonists should be considered in future regimen. Citation Format: Bernhard W. Renz, Marina Macchini, Yoku Hayakawa, C. Benedikt Westphalen, Michael Churchill, Suchetak Kar, Xiaowei Chen, Karan Nagar, Yagnesh Tailor, Daniel L. Worthley, Alina C. Iuga, Ken P. Olive, Timothy C. Wang. Parasympathetic signaling suppresses pancreatic cancer development. [abstract]. In: Proceedings of the 106th Annual Meeting of the American Association for Cancer Research; 2015 Apr 18-22; Philadelphia, PA. Philadelphia (PA): AACR; Cancer Res 2015;75(15 Suppl):Abstract nr 5079. doi:10.1158/1538-7445.AM2015-5079