Expression of Fibronectin Isoforms in Human Breast Tissue: Production of Extra Domain A⁺/Extra Domain B⁺ by Cancer Cells and Extra Domain A⁺ by Stromal Cells

Abstract

The expression of fibronectin (FN) isoforms including extra domain A (EDA) and extra domain B (EDB) segments, was investigated in 36 invasiveMany recent studies have demonstrated that FN is upregulated in cancer tissues, with reappearance of alternatively spliced isoforms. [6][7][8][9] In breast cancers, immunohistochemical studies using specific monoclonal antibodies have demonstrated that FN isoforms, including EDA (EDA + FN) and EDB (EDB + FN) can be detected in cancer stroma. [10][11][12] In contrast, it has been considered that the effect of the splicing may be quantitative rather than qualitative, 13) and the functional significance of molecular differences has yet to be clarified in detail. However, recent studies have demonstrated that EDA + FN exhibits a high affinity for integrin, 14) and EDB + isoform induces tyrosine phosphorylation of focal adhesion proteins. 15)To establish the possible roles of different FN isoforms in cancer progression, it is important to clarify the cellular sources of these isoforms. Therefore, we examined mRNA expression of EDA and EDB, and well as total FN isoforms, by in situ hybridization (ISH) using cRNA probes specific to the constant region and alternatively spliced sites, in benign and malignant human breast lesions. MATERIALS AND METHODSTissues A total of 49 human breast tumors (36 invasive ductal carcinomas and 13 benign tumors) were investigated. All tissues were surgically resected, and immediately fixed in 4% paraformaldehyde in 0.1 M phosphate buffer (PB), pH 7.4, at 4°C overnight. After having been rinsed in PB, they were dehydrated through a graded ethanol series and xylene, embedded in paraffin, sectioned at 4 µm, and placed on silane-coated glass slides (Dako Japan, Kyoto).Histological classification was made using sections stained with hematoxylin and eosin. To examine the relationship of expression of FN isoforms to morphological

The Extra-domain A of Fibronectin Is a Vascular Marker of Solid Tumors and Metastases

“…Furthermore, whereas there are reports about EDA expression in tumor cells and in solid tumors at the mRNA level (see, e.g., refs. 44,45), at the level of isolated protein (46) and at the immunohistochemical level (21, 47-50), we could not find any report of EDA expression in the neovasculature of liver and lung metastases. The work presented in this article strongly encourages the clinical development of anti-EDA antibody derivatives, in full analogy to anti-EDB antibodies.…”

Breast fibroblasts modulate epithelial cell proliferation in three-dimensional in vitro co-culture

“…These documented characteristics of breast-derived CAF are thoroughly reviewed by Kunz-Schughart and Knuechel [1,2], and include an increased expression of several growth factors [3,34], of ECM molecules [35-37], and of proteases and protease inhibitors involved in modulating the ECM [5,6]. Many of these differences in the expression profile of CAF in comparison with NAF have the potential to enhance the development, growth and progression of breast carcinoma [1].…”

Induction of epithelial to mesenchymal transition in PMC42-LA human breast carcinoma cells by carcinoma-associated fibroblast secreted factors

“…CAFs differ from NMFs also in their increased expression of growth factors [16,17], and different profiles of ECM molecule synthesis [18-20] and ECM-altering proteases and protease inhibitors [21,22]. The role played by fibroblasts in the development or progression of cancer is not yet fully understood, and the use of physiologically relevant co-culture models using fibroblasts from normal and cancer stroma may provide a tool for the analysis of the effect of fibroblasts.…”