Pancreatic Tumor Microenvironment Factor Promotes Cancer Stemness via SPP1-CD44 Axis

Gastroenterology. 2021 Dec;161(6):1998-2013.e7. doi: 10.1053/j.gastro.2021.08.023. Epub 2021 Aug 19.

Abstract

Background & aims: Tumor-microenvironment factors and cancer stem cells (CSCs) play a critical role in the aggressiveness of pancreatic cancer (PC). However, the degree to which tumor-microenvironment factors promote stemness remains unexplored. Here, we examined whether cancer-associated fibroblasts (CAFs) promote CSC features in PC.

Methods: PC cells were treated long-term (30, 60, and 90 days) with conditioned media (CM)-derived from normal human fibroblasts (NFs) and CAFs. The stemness features of tumorsphere formation and stemness populations, along with CSCs markers, were analyzed using 2-dimensional and 3-dimensional sodium alginate bead-based co-culture models. Immunohistochemistry and immunofluorescence staining were performed for CSCs and fibroblast markers in autochthonous KrasG12D/+; Trp53R172H/+; Pdx1-Cre mice and human pancreatic tumors. Polymerase chain reaction array and gene knockdown were performed to identify the mechanism of stemness enrichment.

Results: Long-term treatment of PC cells with CAF-CM enriched stemness, as indicated by significantly higher CD44+, ALDH+, and AF+ populations in PC cells. Increased tumorsphere formation and elevated CSC, self-renewal, and drug-resistance markers in CAF-CM-treated PC cells were observed. In addition, CAFs co-cultured with PC cells in the 3-dimensional model showed a substantial increase in stemness features. CD44 and α-smooth muscle actin were positively correlated and their expressions progressively increased from the early to late stages of KrasG12D/+; Trp53R172H/+; Pdx1-Cre mouse and human pancreatic tumors. Osteopontin/secreted phosphoprotein 1 was identified as the top differentially overexpressed gene in CAF-CM-treated PC cells and knockdown of osteopontin/secreted phosphoprotein 1 significantly reduced stemness characteristics in CAF-CM-treated PC cells.

Conclusions: Our data uncovered novel insight into the interplay between CAF and enrichment of stemness population through the osteopontin/secreted phosphoprotein 1-CD44 axis in PC.

Keywords: CD44; Cancer Stem Cells; Cancer-Associated Fibroblast; OPN/SPP1; Pancreatic Cancer.

Publication types

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

MeSH terms

  • Animals
  • Cancer-Associated Fibroblasts / metabolism*
  • Cancer-Associated Fibroblasts / pathology
  • Carcinoma, Pancreatic Ductal / genetics
  • Carcinoma, Pancreatic Ductal / metabolism*
  • Carcinoma, Pancreatic Ductal / pathology
  • Cell Line, Tumor
  • Cell Movement
  • Cell Proliferation
  • Coculture Techniques
  • Epithelial-Mesenchymal Transition
  • Gene Expression Regulation, Neoplastic
  • Humans
  • Hyaluronan Receptors / genetics
  • Hyaluronan Receptors / metabolism*
  • Male
  • Mice
  • Mice, Nude
  • Mice, Transgenic
  • Neoplasm Invasiveness
  • Neoplastic Stem Cells / metabolism*
  • Neoplastic Stem Cells / pathology
  • Osteopontin / genetics
  • Osteopontin / metabolism*
  • Pancreatic Neoplasms / genetics
  • Pancreatic Neoplasms / metabolism*
  • Pancreatic Neoplasms / pathology
  • Paracrine Communication
  • Phenotype
  • Signal Transduction
  • Tumor Microenvironment*

Substances

  • CD44 protein, human
  • Cd44 protein, mouse
  • Hyaluronan Receptors
  • SPP1 protein, human
  • Spp1 protein, mouse
  • Osteopontin