Murine pancreatic adenocarcinoma dampens SHIP-1 expression and alters MDSC homeostasis and function

PLoS One. 2011;6(11):e27729. doi: 10.1371/journal.pone.0027729. Epub 2011 Nov 22.


Background: Pancreatic cancer is one of the most aggressive cancers, with tumor-induced myeloid-derived suppressor cells (MDSC) contributing to its pathogenesis and ineffective therapies. In response to cytokine/chemokine receptor activation, src homology 2 domain-containing inositol 5'-phosphatase-1 (SHIP-1) influences phosphatidylinositol-3-kinase (PI3K) signaling events, which regulate immunohomeostasis. We hypothesize that factors from murine pancreatic cancer cells cause the down-regulation of SHIP-1 expression, which may potentially contribute to MDSC expansion, and the suppression of CD8(+) T cell immune responses. Therefore, we sought to determine the role of SHIP-1 in solid tumor progression, such as murine pancreatic cancer.

Methodology and principal findings: Immunocompetent C57BL/6 mice were inoculated with either murine Panc02 cells (tumor-bearing [TB] mice) or Phosphate Buffer Saline (PBS) (control mice). Cytometric Bead Array (CBA) analysis of supernatants of cultured Panc02 detected pro-inflammatory cytokines such as IL-6, IL-10 and MCP-1. TB mice showed a significant increase in serum levels of pro-inflammatory factors IL-6 and MCP-1 measured by CBA. qRT-PCR and Western blot analyses revealed the in vivo down-regulation of SHIP-1 expression in splenocytes from TB mice. Western blot analyses also detected reduced SHIP-1 activity, increased AKT-1 and BAD hyper-phosphorylation and up-regulation of BCL-2 expression in splenocytes from TB mice. In vitro, qRT-PCR and Western blot analyses detected reduced SHIP-1 mRNA and protein expression in control splenocytes co-cultured with Panc02 cells. Flow cytometry results showed significant expansion of MDSC in peripheral blood and splenocytes from TB mice. AutoMACS sorted TB MDSC exhibited hyper-phosphorylation of AKT-1 and over-expression of BCL-2 detected by western blot analysis. TB MDSC significantly suppressed antigen-specific CD8(+) T cell immune responses in vitro.

Conclusion/significance: SHIP-1 may regulate immune development that impacts MDSC expansion and function, contributing to pancreatic tumor progression. Thus, SHIP-1 can be a potential therapeutic target to help restore immunohomeostasis and improve therapeutic responses in patients with pancreatic cancer.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adenocarcinoma / complications
  • Adenocarcinoma / enzymology*
  • Adenocarcinoma / genetics
  • Adenocarcinoma / pathology*
  • Animals
  • Cell Line, Tumor
  • Cell Survival
  • Coculture Techniques
  • Down-Regulation
  • Epitopes / immunology
  • Female
  • Gene Expression Regulation, Neoplastic
  • Homeostasis*
  • Inflammation Mediators / metabolism
  • Inositol Polyphosphate 5-Phosphatases
  • Mice
  • Mice, Inbred C57BL
  • Myeloid Cells / metabolism
  • Myeloid Cells / pathology*
  • Pancreatic Neoplasms / complications
  • Pancreatic Neoplasms / enzymology*
  • Pancreatic Neoplasms / genetics
  • Pancreatic Neoplasms / pathology*
  • Phosphatidylinositol-3,4,5-Trisphosphate 5-Phosphatases
  • Phosphoric Monoester Hydrolases / genetics
  • Phosphoric Monoester Hydrolases / metabolism*
  • Proto-Oncogene Proteins c-akt / metabolism
  • Proto-Oncogene Proteins c-bcl-2 / metabolism
  • Spleen / enzymology
  • Spleen / pathology
  • Splenomegaly / complications
  • Splenomegaly / pathology
  • T-Lymphocytes / immunology


  • Epitopes
  • Inflammation Mediators
  • Proto-Oncogene Proteins c-bcl-2
  • Proto-Oncogene Proteins c-akt
  • Phosphoric Monoester Hydrolases
  • Inositol Polyphosphate 5-Phosphatases
  • Inpp5d protein, mouse
  • Phosphatidylinositol-3,4,5-Trisphosphate 5-Phosphatases