Stromal fibroblasts from the interface zone of human breast carcinomas induce an epithelial–mesenchymal transition-like state in breast cancer cells in vitro

Ming-Qing Gao,Yoon Pyo Choi,Suki Kang,Nam Hoon Cho,Hangran Park,Kyu Sub Kang,Baek Gil Kim

doi:10.1242/jcs.072900

Abstract

Fibroblasts were extracted from tissue in tumor burden zones, distal normal zones and interface zones between tumor and normal tissue of human breast carcinomas, and the corresponding fibroblasts were designated as cancer-associated fibroblasts (CAFs), normal zone fibroblasts (NFs) and interface zone fibroblasts (INFs). The crosstalk between three types of fibroblasts and breast cancer cells was evaluated using an in vitro direct co-culture model. We found that INFs grew faster and expressed higher levels of fibroblast activation protein than did NFs and CAFs. Compared with CAFs and NFs, INFs grown with breast cancer cells were significantly more effective in inducing an epithelial-mesenchymal transition (EMT) in cancer cells, as indicated by induction of vimentin and N-cadherin and downregulation of E-cadherin. This EMT process was also accompanied by activation of extracellular signal-regulated kinase (ERK) and modulation of membrane-type 1 matrix metalloproteinase (MT1-MMP) expression. Additionally, INFs promoted breast cell migration to a larger extent compared with NFs and CAFs. Taken together, these findings indicate that INFs isolated from the tumor interface zone exhibited more robust biological modulatory activity than did NFs and CAFs isolated from normal and tumor zones of the same tumor tissue, suggesting that the interface zone of the tumor represents a dynamic region vital to tumor progression.

Highlights

Breast cancer is a major health problem that affects the lives of millions of women worldwide each year
We found that fibroblasts isolated from different tumor stromal zones differed with respect to their ability to induce epithelial–mesenchymal transition (EMT), modulate expression of membrane-type 1 matrixmetalloproteinase (MT1-MMP), activate the extracellular signal-regulated kinase (ERK) signaling cascade and promote cancer cell migration
Comparison of primary fibroblasts isolated from different zones of human breast tumor tissue Breast cancer tissues were acquired from six patients by macroscopic dissection after the following geographic mapping: (1) real tumor burden, termed the tumor zone, located at the epicenter of the tumor tissue; (2) normal-like tissue located up to 5 mm from the invasive front of the tumor, termed the interface zone; and (3) distal normal tissue located at least 10 mm from the tumor margin, termed the normal zone (Fig. 1A)

Summary

Introduction

Breast cancer is a major health problem that affects the lives of millions of women worldwide each year. The fibroblast is one of the most crucial components of the tumor microenvironment, which promotes the growth and invasion of cancer cells through the involvement in angiogenesis (Orimo et al, 2005), EMT (Radisky et al, 2005), progressive genetic instability, deregulation of anti-tumor immune responses (Djouad et al, 2003), and synthesis, deposition and remodeling of the extracellular matrix (ECM) (Bhowmick et al, 2004) Such fibroblasts, known as cancer-associated fibroblasts (CAFs), when mixed with oncogene-expressing mammary epithelial cells, promote faster tumor growth than fibroblasts extracted from cancer-free breast tissues (Orimo et al, 2005; Shekhar et al, 2001). The functional contributions of fibroblasts located in the interface zone between the tumor invasion front and the remote normal zone to cancer cells remain poorly understood

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Discussion

Conclusion