Cancer‐associated fibroblasts predict poor outcome and promote periostin‐dependent invasion in oesophageal adenocarcinoma

<jats:title>Abstract</jats:title><jats:p>Interactions between cancer cells and cancer‐associated fibroblasts (<jats:styled-content style="fixed-case">CAFs</jats:styled-content>) play an important role in tumour development and progression. In this study we investigated the functional role of <jats:styled-content style="fixed-case">CAFs</jats:styled-content> in oesophageal adenocarcinoma (<jats:styled-content style="fixed-case">EAC</jats:styled-content>). We used immunochemistry to analyse a cohort of 183 <jats:styled-content style="fixed-case">EAC</jats:styled-content> patients for <jats:styled-content style="fixed-case">CAF</jats:styled-content> markers related to disease mortality. We characterized <jats:styled-content style="fixed-case">CAFs</jats:styled-content> and normal oesophageal fibroblasts (<jats:styled-content style="fixed-case">NOFs</jats:styled-content>) using western blotting, immunofluorescence and gel contraction. Transwell assays, <jats:styled-content style="fixed-case">3D</jats:styled-content> organotypic culture and xenograft models were used to examine the effects on <jats:styled-content style="fixed-case">EAC</jats:styled-content> cell function and to dissect molecular mechanisms regulating invasion. Most <jats:styled-content style="fixed-case">EACs</jats:styled-content> (93%) contained <jats:styled-content style="fixed-case">CAFs</jats:styled-content> with a myofibroblastic (α‐<jats:styled-content style="fixed-case">SMA</jats:styled-content>‐positive) phenotype, which correlated significantly with poor survival [<jats:italic>p =</jats:italic> 0.016; <jats:styled-content style="fixed-case">HR</jats:styled-content> 7. 1 (1.7–29.4)]. Primary <jats:styled-content style="fixed-case">CAFs</jats:styled-content> isolated from <jats:styled-content style="fixed-case">EACs</jats:styled-content> have a contractile, myofibroblastic phenotype and promote <jats:styled-content style="fixed-case">EAC</jats:styled-content> cell invasion <jats:italic>in vitro</jats:italic> (Transwell assays, <jats:italic>p</jats:italic> ≤ 0.05; organotypic culture, <jats:italic>p <</jats:italic> 0.001) and <jats:italic>in vivo</jats:italic> (<jats:italic>p</jats:italic> ≤ 0.05). <jats:italic>In vitro</jats:italic>, this pro‐invasive effect is modulated through the matricellular protein periostin. Periostin is secreted by <jats:styled-content style="fixed-case">CAFs</jats:styled-content> and acts as a ligand for <jats:styled-content style="fixed-case">EAC</jats:styled-content> cell integrins αvβ3 and αvβ5, promoting activation of the <jats:styled-content style="fixed-case">PI3kinase</jats:styled-content>–Akt pathway. In patient samples, periostin expression at the tumour cell–stromal interface correlates with poor overall and disease‐free survival. Our study highlights the importance of the tumour stroma in <jats:styled-content style="fixed-case">EAC</jats:styled-content> progression. Paracrine interaction between <jats:styled-content style="fixed-case">CAF</jats:styled-content>‐secreted periostin and <jats:styled-content style="fixed-case">EAC</jats:styled-content>‐expressed integrins results in <jats:styled-content style="fixed-case">PI3</jats:styled-content> kinase–Akt activation and increased tumour cell invasion. Most <jats:styled-content style="fixed-case">EACs</jats:styled-content> contain a myofibroblastic <jats:styled-content style="fixed-case">CAF</jats:styled-content>‐rich stroma; this may explain the aggressive, highly infiltrative nature of the disease, and suggests that stromal targeting may produce therapeutic benefit in <jats:styled-content style="fixed-case">EAC</jats:styled-content> patients. © 2014 The Authors. <jats:italic>The Journal of Pathology</jats:italic> published by John Wiley & Sons Ltd on behalf of Pathological Society of Great Britain and Ireland.</jats:p>