Abstract 3954: Regulation of pro-angiogenic and pro-inflammatory cytokines in tumor cells: Implication of epithelial-to-mesenchymal transitions .
Authors: Suarez-Carmona Meggy , Bourcy Morgane , Foidart Jean-Michel , Delvenne Philippe , Noël Agnès , Polette Myriam , Gilles Christine 
Published: August 2014

Increasing data suggest a contribution of epithelial-to-mesenchymal transitions in specific steps of the metastatic cascade, particularly in tumor invasion and intravasation, and in the release of circulating tumor cells (CTCs) in the blood stream. The completion of these steps largely relies on interactions disseminating tumor cells establish with host cells. Because cytokines are particularly implicated in tumor-host cross-talks, we have examined whether EMT programs could be involved in the regulation of pro-inflammatory and pro-angiogenic cytokines which could favor angiogenesis, intravasation and CTC release.

To investigate EMT implication in cytokine regulation, we used two cell lines, MDA-MB-468 (a mammary adenocarcinoma cell line) and A549 (a lung carcinoma cell line). These cell lines were shown to undergo EMT-changes following EGF and TGF-β treatment respectively, characterized by an upregulation of vimentin, snail and slug, and a downregulation of E-cadherin. A cytokine array on cell supernatant showed that EMT induction in these cell lines is associated with the upregulation of a consistant panel of cytokines. We then confirmed that interleukin-8 (IL-8), interleukin-6 (IL-6) and Granulocyte Monocyte-Colony Stimulating Factor (GM-CSF) are upregulated during EMT in the two carcinoma cell lines by RT-qPCR and ELISA. Emphasizing a functional role of such regulations, conditioned medium from EMT-induced MDA-468 cells was shown to stimulate HUVEC cell migration in a boyden chamber assay.

In order to investigate whether slug and snail EMT transcription factors are involved in the regulation of IL-8, IL-6 and GM-CSF, we used both siRNA and cDNA transfection approaches. Combined repression of snail and slug inhibited the EMT-associated upregulation of IL-8, IL-6 and GM-CSF, suggesting that snail and slug are necessary for this process. Ectopic expression of each transcription factor was not sufficient to induce cytokines expression. However, ectopic expression of a proteasome degradation-resistant mutant of snail was sufficient to induce expression of IL-6, IL-8 and GM-CSF, suggesting that the stabilization of snail is necessary to regulate the expression of these cytokines.

We thus here demonstrate that EMT is associated with an overexpression of specific pro-angiogenic and pro-inflammatory cytokines. We further emphasize a role of snail and slug transcription factors in this regulatory process. These data suggest that EMT programs could directly contribute to the stimulation of angiogenesis and inflammatory cell recruitment in the tumor microenvironment. The impact of such regulations on angiogenesis and the metastatic spread is currently under investigation.

Citation Format: Meggy Suarez-Carmona, Morgane Bourcy, Jean-Michel Foidart, Philippe Delvenne, Agnès Noël, Myriam Polette, Christine Gilles. Regulation of pro-angiogenic and pro-inflammatory cytokines in tumor cells: Implication of epithelial-to-mesenchymal transitions . [abstract]. In: Proceedings of the 104th Annual Meeting of the American Association for Cancer Research; 2013 Apr 6-10; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2013;73(8 Suppl):Abstract nr 3954. doi:10.1158/1538-7445.AM2013-3954