Abstract B73: Adrenergic signaling promotes pancreatic tumor initiation and progression

Abstract

Abstract Background/Aims: There is increasing evidence that chronic sympathetic nervous system activation can lead to increased noradrenaline levels in the tumor microenvironment. This process has been associated with proliferative signals largely mediated by beta-adrenergic signaling. However, the mechanisms by which adrenergic neurotransmitters are delivered to the tumor microenvironment are not well understood. In this study we aimed to investigate the role of locally and systemically delivered catecholamines to the tumor microenvironment in a well-established genetically engineered pancreatic cancer mouse model (PDx1-Cre/KRasG12D (KC) and PDx1-Cre/KRasG12D/Trp53R172H (KPC)). Methods: Adrenergic signaling was induced or inhibited in KC or KPC mice or 3D pancreatic spheres in culture using specific non-selective and selective agonists or antagonists. Adrenergic receptor expression was assessed by RT-PCR, Western blot and immunohistochemistry. Adrenergic signaling was also modeled in vivo applying restraint stress. To elucidate the crosstalk between nerve and cancer cells, pancreatic spheres and pancreatic cancer cells were co-cultured with dorsal root ganglia and neuronal plasticity was quantified by evaluating neurite outgrowth and number of branches. Denervation of the pancreas was performed using surgical or chemical neural ablation. Results: Adrenergic signaling receptors, in particular ADRB2, is upregulated during pancreatic cancer development. Furthermore, in vitro stimulation of cells harboring an oncogenic KRas mutation displayed a significantly increased sphere forming efficiency. This effect was blocked by the non-specific beta-blocker propranolol and the selective beta2-blocker ICI 188,551. Stimulation of pancreatic sphere formation from KC mice induced by adrenergic signaling from dorsal root ganglia in vitro was also prevented by selective blockage of the beta2-adrenergic signaling pathway. While surgical or chemical (Botulinum toxin A) denervation of the pancreas appeared not to retard the development precancerous lesions in KC mice, denervation significantly increased the survival when performed in mice after a tumor (3-5mm) was detected by high–resolution ultrasound imaging. In contrast, stress accelerated pancreatic cancer development in KC mice. The effects of stress were prevented by treatment with the selective ADRB2 antagonist ICI 188,551. Conclusions: Taken together, our data suggests that an increased level of stress and an increased level of systemic catecholamines may promote pancreatic carcinogenesis in its early stages. During this phase, patients might benefit from pharmacological inhibition of stress-induced signaling. The progression of pancreatic cancer seems to depend on the local delivery of catecholamines to the microenvironment, and thus patients might also benefit by additional targeting of the ADRB2 signaling pathway. Citation Format: Bernhard W. Renz, Christoph B. Westphalen, Xiaowei Chen, Yoku Hayakawa, Yoshihiro Takemoto, Marina Macchini, Daniel L. Worthley, Samuel Asfaha, Axel Kleespies, Helen Remotti, Kenneth P. Olive, Timothy C. Wang. Adrenergic signaling promotes pancreatic tumor initiation and progression. [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 B73.