Contribution of fibroblast and mast cell (afferent) and tumor (efferent) IL-6 effects within the tumor microenvironment

Hugo, Honor J., Lebret, Stephanie C., Tomaskovic-Crook, Eva, Ahmed, Nuzhat, Blick, Tony, Newgreen, Donald F., Thompson, Erik W., & Ackland, M.Leigh (2012) Contribution of fibroblast and mast cell (afferent) and tumor (efferent) IL-6 effects within the tumor microenvironment. Cancer Microenvironment, 5(1), pp. 83-93.

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Hyperactive inflammatory responses following cancer initiation have led to cancer being described as a 'wound that never heals'. These inflammatory responses elicit signals via NFκB leading to IL-6 production, and IL-6 in turn has been shown to induce epithelial to mesenchymal transition in breast cancer cells in vitro, implicating a role for this cytokine in cancer cell invasion. We previously have shown that conditioned medium derived from cancer-associated fibroblasts induced an Epithelial to Mesenchymal transition (EMT) in PMC42-LA breast cancer cells and we have now identify IL-6 as present in this medium. We further show that IL-6 is expressed approximately 100 fold higher in a cancer-associated fibroblast line compared to normal fibroblasts. Comparison of mouse-specific (stroma) and human-specific (tumor) IL-6 mRNA expression from MCF-7, MDA MB 468 and MDA MB 231 xenografts also indicated the stroma rather than tumor as a significantly higher source of IL-6 expression. Mast cells (MCs) feature in inflammatory cancer-associated stroma, and activated MCs secrete IL-6. We observed a higher MC index (average number of mast cells per xenograft section/average tumor size) in MDA MB 468 compared to MDA MB 231 xenografts, where all MC were observed to be active (degranulating). This higher MC index correlated with greater mouse-specific IL-6 expression in the MDA MB 468 xenografts, implicating MC as an important source of stromal IL-6. Furthermore, immunohistochemistry on these xenografts for pSTAT3, which lies downstream of the IL-6 receptor indicated frequent correlations between pSTAT3 and mast cell positive cells. Analysis of publically available databases for IL-6 expression in patient tissue revealed higher IL-6 in laser capture microdissected stroma compared to adjacent tissue epithelium from patients with inflammatory breast cancer (IBC) and invasive non-inflammatory breast cancer (non-IBC) and we show that IL-6 expression was significantly higher in Basal versus Luminal molecular/phenotypic groupings of breast cancer cell lines. Finally, we discuss how afferent and efferent IL-6 pathways may participate in a positive feedback cycle to dictate tumor progression.

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ID Code: 72220
Item Type: Journal Article
Refereed: Yes
Additional Information: Cited By (since 1996):5 Export Date: 6 May 2014 Source: Scopus
Additional URLs:
Keywords: Breast cancer, EMT, IL-6, Inflammation, Mast cells, Stroma
DOI: 10.1007/s12307-012-0098-7
ISSN: 1875-2284
Divisions: Current > QUT Faculties and Divisions > Faculty of Health
Deposited On: 29 May 2014 02:57
Last Modified: 29 Aug 2016 07:40

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