Abstract 1327: Epithelial memory of resolved inflammation cooperates with oncogenic KRAS to limit tissue damage while promoting pancreatic cancer
Authors: Ho I-Lin , Poggetto Edoardo Del , Balestrieri Chiara , Yen Er-Yen , Citron Francesca , Shah Rutvi , Zhang Shaojun , Jiang Shan , Yao Wantong , Ying Haoqiang , Genovese Giannicola , Heffernan Timothy , Maitra Anirban , Wang Linghua , Wang Timothy , Draetta Giulio , Carugo Alessandro , Natoli Gioacchino , Viale Andrea 
Published: June 2022

Abstract
The association between tumors and inflammation is a long-established clinical observation. Although many studies demonstrated that the inflammatory microenvironment can promote tumor growth through the activation of survival and proliferation programs in cancer cells, the reason why inflammation, an evolutionarily conserved response to damage aimed at reestablishing tissue integrity upon injury, might be integral to tumorigenesis still remains unknown. Pancreatic ductal adenocarcinoma (PDAC), a tumor characterized by poor prognosis, represents a distinctive example of cooperation between inflammation and activated oncogenes. Frequently developed in a context of chronic pancreatitis, PDAC is always associated with an inflammatory microenvironment. As supported by a substantial body of evidence across a multitude of experimental models, when occurring in the context of pancreatitis, mutations of KRAS, the universal oncogenic driver of pancreatic cancer, lead to accelerated tumor development inducing the appearance of neoplastic precursor lesions, such as acinar-to-ductal metaplasia (ADM) and pancreatic intraepithelial neoplasia (PanIN), which can evolve into invasive tumors. Interestingly, preneoplastic pancreatic alterations, specifically ADM, have been previously identified in acute and chronic pancreatitis in the absence of oncogene activation. Investigating the effects of inflammation on normal pancreatic epithelial cells, we discovered that long after complete resolution a transient inflammatory event primes cells to cooperate with oncogenic KRAS. Indeed, upon recovery from a single acute inflammation, epithelial cells display an enduring adaptive response associated with sustained epigenetic and transcriptional reprogramming. Such adaptation facilitates the prompt reactivation of acinar-to-ductal metaplasia upon subsequent inflammatory events, representing a physiological mechanism for limiting tissue damage via rapid decrease of zymogen production. Because metaplastic lesions are mediated by the activation of MAPK signaling, we demonstrated that activating mutations of KRAS, maintaining an irreversible ADM, are protective against tissue damage in a contest of pancreatitis. Uncovering a new physiologic role of somatic oncogenic mutations in preserving tissue integrity during repeated damages, we propose that KRAS mutations represent a nearly universal event in pancreatic cancer because beneficial and under strong positive selection in the context of recurrent pancreatitis.
Citation Format: I-Lin Ho, Edoardo Del Poggetto, Chiara Balestrieri, Er-Yen Yen, Francesca Citron, Rutvi Shah, Shaojun Zhang, Shan Jiang, Wantong Yao, Haoqiang Ying, Giannicola Genovese, Timothy Heffernan, Anirban Maitra, Linghua Wang, Timothy Wang, Giulio Draetta, Alessandro Carugo, Gioacchino Natoli, Andrea Viale. Epithelial memory of resolved inflammation cooperates with oncogenic KRAS to limit tissue damage while promoting pancreatic cancer [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2022; 2022 Apr 8-13. Philadelphia (PA): AACR; Cancer Res 2022;82(12_Suppl):Abstract nr 1327.