Blockade of Stromal Gas6 Alters Cancer Cell Plasticity, Activates NK Cells, and Inhibits Pancreatic Cancer Metastasis

Front Immunol. 2020 Feb 27;11:297. doi: 10.3389/fimmu.2020.00297. eCollection 2020.

Abstract

Pancreatic ductal adenocarcinoma (PDA) is one of the deadliest cancers due to its aggressive and metastatic nature. PDA is characterized by a rich tumor stroma with abundant macrophages, fibroblasts, and collagen deposition that can represent up to 90% of the tumor mass. Activation of the tyrosine kinase receptor AXL and expression of its ligand growth arrest-specific protein 6 (Gas6) correlate with a poor prognosis and increased metastasis in pancreatic cancer patients. Gas6 is a multifunctional protein that can be secreted by several cell types and regulates multiple processes, including cancer cell plasticity, angiogenesis, and immune cell functions. However, the role of Gas6 in pancreatic cancer metastasis has not been fully investigated. In these studies we find that, in pancreatic tumors, Gas6 is mainly produced by tumor associated macrophages (TAMs) and cancer associated fibroblasts (CAFs) and that pharmacological blockade of Gas6 signaling partially reverses epithelial-to-mesenchymal transition (EMT) of tumor cells and supports NK cell activation, thereby inhibiting pancreatic cancer metastasis. Our data suggest that Gas6 simultaneously acts on both the tumor cells and the NK cells to support pancreatic cancer metastasis. This study supports the rationale for targeting Gas6 in pancreatic cancer and use of NK cells as a potential biomarker for response to anti-Gas6 therapy.

Keywords: Gas6; NK cells; fibroblasts; macrophages; metastasis; pancreatic cancer.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Axl Receptor Tyrosine Kinase
  • Cancer-Associated Fibroblasts / physiology
  • Carcinoma, Pancreatic Ductal / pathology*
  • Cell Line, Tumor
  • Cell Plasticity
  • Collagen / metabolism
  • Epithelial-Mesenchymal Transition
  • Female
  • Humans
  • Intercellular Signaling Peptides and Proteins / physiology*
  • Killer Cells, Natural / immunology*
  • Lymphocyte Activation*
  • Mice
  • Mice, Inbred C57BL
  • Neoplasm Metastasis
  • Neovascularization, Pathologic / etiology
  • Pancreatic Neoplasms / blood supply
  • Pancreatic Neoplasms / drug therapy
  • Pancreatic Neoplasms / immunology
  • Pancreatic Neoplasms / pathology*
  • Proto-Oncogene Proteins / physiology
  • Receptor Protein-Tyrosine Kinases / physiology
  • Tumor-Associated Macrophages / physiology

Substances

  • Intercellular Signaling Peptides and Proteins
  • Proto-Oncogene Proteins
  • growth arrest-specific protein 6
  • Collagen
  • Receptor Protein-Tyrosine Kinases
  • Axl Receptor Tyrosine Kinase