Neutrophil extracellular traps promote liver micrometastasis in pancreatic ductal adenocarcinoma via the activation of cancer‑associated fibroblasts

Int J Oncol. 2020 Feb;56(2):596-605. doi: 10.3892/ijo.2019.4951. Epub 2019 Dec 24.

Abstract

Cancer‑associated fibroblasts (CAFs) promote the progression of pancreatic ductal adenocarcinoma (PDAC) via tumor‑stromal interactions. Neutrophil extracellular traps (NETs) are extracellular DNA meshworks released from neutrophils together with proteolytic enzymes against foreign pathogens. Emerging studies suggest their contribution to liver metastasis in several types of cancer. Herein, in order to investigate the role of NETs in liver metastasis in PDAC, the effects of NET inhibitors on spontaneous PDAC mouse models were evaluated. It was demonstrated that DNase I, a NET inhibitor, suppressed liver metastasis. For further investigation, further attention was paid to liver micrometastasis and an experimental liver metastasis mouse model was used that was generated by intrasplenic tumor injection. Furthermore, DNase I also suppressed liver micrometastasis and notably, CAFs accumulated in metastatic foci were significantly decreased in number. In vitro experiments revealed that pancreatic cancer cells induced NET formation and consequently NETs enhanced the migration of hepatic stellate cells, which was the possible origin of CAFs in liver metastasis. On the whole, these results suggest that NETs promote liver micrometastasis in PDAC via the activation of CAFs.

MeSH terms

  • Aged
  • Animals
  • Cancer-Associated Fibroblasts / immunology*
  • Carcinoma, Pancreatic Ductal / immunology*
  • Carcinoma, Pancreatic Ductal / secondary
  • Carcinoma, Pancreatic Ductal / surgery
  • Cell Culture Techniques
  • Cell Line, Tumor / transplantation
  • Cell Movement / immunology
  • Cell Proliferation
  • Coculture Techniques
  • Deoxyribonuclease I / administration & dosage
  • Disease Models, Animal
  • Extracellular Traps / drug effects
  • Extracellular Traps / immunology
  • Extracellular Traps / metabolism
  • Hepatic Stellate Cells
  • Humans
  • Injections, Intraperitoneal
  • Liver Neoplasms / immunology*
  • Liver Neoplasms / secondary
  • Male
  • Neoplasm Micrometastasis / immunology
  • Neoplasm Micrometastasis / prevention & control
  • Neutrophils / immunology*
  • Neutrophils / metabolism
  • Pancreas / immunology
  • Pancreas / pathology
  • Pancreas / surgery
  • Pancreatic Neoplasms / immunology
  • Pancreatic Neoplasms / pathology*
  • Pancreatic Neoplasms / surgery
  • Pancreaticoduodenectomy
  • Primary Cell Culture

Substances

  • Deoxyribonuclease I