Macrophage activation increases the invasive properties of hepatoma cells by destabilization of the adherens junction

Authors:
  • CLChien-Jung Lin
    Chien-Jung Lin
  • KCKuo-Hsing Chen
    Kuo-Hsing Chen
  • JWJiann-Chun Wu
    Jiann-Chun Wu
  • SHShih-Horng Huang
    Shih-Horng Huang
  • SWSeu-Mei Wang
    Seu-Mei Wang
Publisher website
Google Scholar
Abstract
Tumor‐associated macrophages play an important role in tumor progression, but whether they exert a tumor‐progressive effect remains controversial. Here, we demonstrated that activated macrophage‐conditioned medium (AMCM) obtained from RAW macrophages (RAW/AMCM) induced epithelial‐mesenchymal transition (EMT) and stimulated the migratory and invasive activities of HepG2 cells, whereas control conditioned media had no effect. Epithelial‐cadherin (E‐cadherin) and β‐catenin staining patterns were altered at the adherens junctions by RAW/AMCM treatment, with an approximately 50% decrease in E‐cadherin and β‐catenin in the cell membrane. Importantly, levels of β‐catenin‐associated E‐cadherin were also decreased. Following RAW/AMCM treatment, enhanced activation of c‐Src was seen prior to increased tyrosine phosphorylation of β‐catenin, and this led to the destabilization of adherens junctions. Pretreatment of HepG2 cells with the Src kinase inhibitor, PP2, completely abolished the effects of RAW/AMCM on the EMT, migration, invasion, and expression and association of E‐cadherin and β‐catenin. AMCMs obtained from human THP‐1 monocytes and mouse peritoneal macrophages also caused disassembly of the adherens junctions and migration of HepG2 cells. Furthermore, inhibition of the epidermal growth factor receptor (EGFR) with gefitinib partially prevented the downregulation of E‐cadherin and β‐catenin at the adherens junctions and migration behavior induced by RAW/AMCM. Our results suggest that activated macrophages have a tumor‐progressive effect on HepG2 cells which involves the c‐Src‐ and EGFR‐dependent signaling cascades.

This publication has 41 references indexed in Scilit: