Clinical-relevant model of intraductal papillary mucinous neoplasm induced by ARID1A loss.

Abstract

e14696 Background: Intraductal papillary mucinous neoplasm (IPMN) constitutes a precursor lesion for malignancy of pancreas. Genes encoding subunits of SWI/SNF chromatin-remodeling complexes like ARID1A are collectively mutated in a significant proportion of patients with pancreatic neoplasm. In the present study, we characterize the role of ARID1A in pancreatic tumorigenesis using genetic engineering mouse models. Methods: Various mouse strains were interbred to obtain pancreas-specific Arid1aflox, KrasLSL-G12D/+; Arid1aflox, KrasLSL-G12D/+; Tgfbr2flox; Arid1aflox, and various littermate control animals. Tissue microarrays were used to determine the expression of ARID1A in human pancreatic ductal adenocarcinoma and IPMN. Results: Arid1a loss in pancreas of mice incurred pancreatic duct dilation and development of cystic lesions. Concomitant Kras mutation and Arid1a inactivation accelerated formation of cystic neoplasm resembling human IPMN. These lesions were reminiscent of specific subtype of IPMN given their morphology and expression pattern of mucin proteins. Histological examination further revealed the step-wise progression of these neoplasm from low-grade to high-grade dysplasia and even invasive carcinoma. TGFBR2 deletion promoted the malignant transformation of IPMN to invasive carcinoma in the background of Kras and Arid1a alterations. Analysis of human tissues consistently showed negative or low expression of ARID1A in over half of IPMN patients. Moreover, patients with pancreatic adenocarcinoma also exhibited downregulated ARID1A expression, and reduced expression correlated with worse prognosis. Conclusions: We have established a preclinical mouse model of pancreatic cystic tumor closely resembling human IPMN. This is helpful for the further understanding of biology of IPMN and highlight therapeutic niches for patient tailored treatment in those with altered SWI/SNF function.