ARID1A Maintains Differentiation of Pancreatic Ductal Cells and Inhibits Development of Pancreatic Ductal Adenocarcinoma in Mice

Gastroenterology. 2018 Jul;155(1):194-209.e2. doi: 10.1053/j.gastro.2018.03.039. Epub 2018 Mar 29.

Abstract

Background & aims: The ARID1A gene encodes a protein that is part of the large adenosine triphosphate (ATP)-dependent chromatin remodeling complex SWI/SNF and is frequently mutated in human pancreatic ductal adenocarcinomas (PDACs). We investigated the functions of ARID1A during formation of PDACs in mice.

Methods: We performed studies with Ptf1a-Cre;KrasG12D mice, which express activated Kras in the pancreas and develop pancreatic intraepithelial neoplasias (PanINs), as well as those with disruption of Aird1a (Ptf1a-Cre;KrasG12D;Arid1af/f mice) or disruption of Brg1 (encodes a catalytic ATPase of the SWI/SNF complex) (Ptf1a-Cre;KrasG12D; Brg1f/fmice). Pancreatic ductal cells (PDCs) were isolated from Arid1af/f mice and from Arid1af/f;SOX9OE mice, which overexpress human SOX9 upon infection with an adenovirus-expressing Cre recombinase. Pancreatic tissues were collected from all mice and analyzed by histology and immunohistochemistry; cells were isolated and grown in 2-dimensional and 3-dimensional cultures. We performed microarray analyses to compare gene expression patterns in intraductal papillary mucinous neoplasms (IPMNs) from the different strains of mice. We obtained 58 samples of IPMNs and 44 samples of PDACs from patients who underwent pancreatectomy in Japan and analyzed them by immunohistochemistry.

Results: Ptf1a-Cre;KrasG12D mice developed PanINs, whereas Ptf1a-Cre;KrasG12D;Arid1af/f mice developed IPMNs and PDACs; IPMNs originated from PDCs. ARID1A-deficient IPMNs did not express SOX9. ARID1A-deficient PDCs had reduced expression of SOX9 and dedifferentiated in culture. Overexpression of SOX9 in these cells allowed them to differentiate and prevented dilation of ducts. Among mice with pancreatic expression of activated Kras, those with disruption of Arid1a developed fewer PDACs from IPMNs than mice with disruption of Brg1. ARID1A-deficient IPMNs had reduced activity of the mTOR pathway. Human IPMN and PDAC specimens had reduced levels of ARID1A, SOX9, and phosphorylated S6 (a marker of mTOR pathway activation). Levels of ARID1A correlated with levels of SOX9 and phosphorylated S6.

Conclusions: ARID1A regulates expression of SOX9, activation of the mTOR pathway, and differentiation of PDCs. ARID1A inhibits formation of PDACs from IPMNs in mice with pancreatic expression of activated KRAS and is down-regulated in IPMN and PDAC tissues from patients.

Keywords: Oncogene; Pancreatic Cancer; Transcriptional Regulator; Tumorigenesis.

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adenocarcinoma in Situ / genetics*
  • Adenocarcinoma in Situ / metabolism
  • Animals
  • Carcinogenesis / genetics
  • Carcinoma, Pancreatic Ductal / genetics*
  • Carcinoma, Pancreatic Ductal / metabolism
  • Cell Culture Techniques
  • Cell Differentiation / genetics*
  • DNA-Binding Proteins / genetics*
  • Mice
  • Nuclear Proteins / genetics*
  • Pancreatic Ducts / cytology*
  • Pancreatic Neoplasms / genetics*
  • Pancreatic Neoplasms / metabolism
  • Proto-Oncogene Proteins p21(ras) / genetics*
  • Proto-Oncogene Proteins p21(ras) / metabolism
  • SOX9 Transcription Factor / genetics*
  • Transcription Factors

Substances

  • Arid1a protein, mouse
  • DNA-Binding Proteins
  • Nuclear Proteins
  • SOX9 Transcription Factor
  • Sox9 protein, mouse
  • Transcription Factors
  • Hras protein, mouse
  • Proto-Oncogene Proteins p21(ras)