Palladin isoforms 3 and 4 regulate cancer-associated fibroblast pro-tumor functions in pancreatic ductal adenocarcinoma

Sci Rep. 2021 Feb 15;11(1):3802. doi: 10.1038/s41598-021-82937-3.

Abstract

Pancreatic Ductal Adenocarcinoma (PDAC) has a five-year survival under 10%. Treatment is compromised due to a fibrotic-like stromal remodeling process, known as desmoplasia, which limits therapeutic perfusion, supports tumor progression, and establishes an immunosuppressive microenvironment. These processes are driven by cancer-associated fibroblasts (CAFs), functionally activated through transforming growth factor beta1 (TGFβ1). CAFs produce a topographically aligned extracellular matrix (ECM) that correlates with reduced overall survival. Paradoxically, ablation of CAF populations results in a more aggressive disease, suggesting CAFs can also restrain PDAC progression. Thus, unraveling the mechanism(s) underlying CAF functions could lead to therapies that reinstate the tumor-suppressive features of the pancreatic stroma. CAF activation involves the f-actin organizing protein palladin. CAFs express two palladin isoforms (iso3 and iso4) which are up-regulated in response to TGFβ1. However, the roles of iso3 and iso4 in CAF functions remain elusive. Using a CAF-derived ECM model, we uncovered that iso3/iso4 are required to sustain TGFβ1-dependent CAF activation, secrete immunosuppressive cytokines, and produce a pro-tumoral ECM. Findings demonstrate a novel role for CAF palladin and suggest that iso3/iso4 regulate both redundant and specific tumor-supportive desmoplastic functions. This study highlights the therapeutic potential of targeting CAFs to restore fibroblastic anti-tumor activity in the pancreatic microenvironment.

Publication types

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

MeSH terms

  • Adenocarcinoma / genetics*
  • Adenocarcinoma / pathology
  • Aged
  • Cancer-Associated Fibroblasts / metabolism
  • Cancer-Associated Fibroblasts / pathology
  • Carcinoma, Pancreatic Ductal / genetics*
  • Carcinoma, Pancreatic Ductal / pathology
  • Cell Line, Tumor
  • Cell Proliferation / genetics
  • Cytoskeletal Proteins / genetics*
  • Extracellular Matrix / genetics
  • Female
  • Gene Expression Regulation, Neoplastic / genetics
  • Humans
  • Male
  • Middle Aged
  • Pancreas / metabolism
  • Pancreas / pathology
  • Protein Isoforms / genetics
  • Transforming Growth Factor beta1 / genetics*
  • Tumor Microenvironment / genetics

Substances

  • Cytoskeletal Proteins
  • PALLD protein, human
  • Protein Isoforms
  • TGFB1 protein, human
  • Transforming Growth Factor beta1