J Cancer 2016; 7(5):546-554. doi:10.7150/jca.14169

Research Paper

Neutrophil Granulocytes in Ovarian Cancer - Induction of Epithelial-To-Mesenchymal-Transition and Tumor Cell Migration

Christine Mayer1, Silvia Darb-Esfahani2,3, Anne-Sophie Meyer4, Katrin Hübner5, Joachim Rom1, Christof Sohn1, Ioana Braicu3,6, Jalid Sehouli3,6, G. Maria Hänsch7, Matthias M. Gaida4✉

1. Department of Gynecology and Obstetrics, University Hospital Heidelberg, Germany;
2. Institute of Pathology, Charité, University Hospital Berlin, Germany;
3. Tumorbank Ovarian Cancer Network (TOC), Berlin, Germany;
4. Institute of Pathology, University Hospital Heidelberg, Germany;
5. BioQuant, COS Heidelberg, University Heidelberg, Germany;
6. Department of Gynecology, Charité University Hospital Berlin, Germany;
7. Institute of Immunology, University Hospital Heidelberg, Germany.

This is an open access article distributed under the terms of the Creative Commons Attribution (CC BY-NC) License. See http://ivyspring.com/terms for full terms and conditions.
Mayer C, Darb-Esfahani S, Meyer AS, Hübner K, Rom J, Sohn C, Braicu I, Sehouli J, Hänsch GM, Gaida MM. Neutrophil Granulocytes in Ovarian Cancer - Induction of Epithelial-To-Mesenchymal-Transition and Tumor Cell Migration. J Cancer 2016; 7(5):546-554. doi:10.7150/jca.14169. Available from http://www.jcancer.org/v07p0546.htm

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Background: Ovarian cancer (OvCa) is a highly aggressive malignoma with a tumor-promoting microenvironment. Infiltration of polymorphonuclear neutrophils (PMN) is frequently seen, raising the question of their impact on tumor development. In that context, effects of PMN on human ovarian cancer cells were assessed.

Methods: Human epithelial ovarian cancer cells were incubated with human PMN, lysate of PMN, or neutrophil elastase. Morphological alterations were observed by time-lapse video-microscopy, and the underlying molecular mechanism was analyzed by flow cytometry and Western blotting. Functional alternations were assessed by an in vitro wound healing assay. In parallel, a large cohort of n=334 primary OvCa tissue samples of various histological subtypes was histologically evaluated.

Results: Co-cultivation of cancer cells with either PMN or PMN lysate causes a change of the polygonal epithelial phenotype of the cells towards a spindle shaped morphology, causing a cribriform cell growth. The PMN-induced alteration could be attributed to elastase, a major protease of PMN. Elastase-induced shape change was most likely due to the degradation of membranous E-cadherin, which results in loss of cell contacts and polarity. Moreover, in response to elastase, epithelial cytokeratins were downmodulated, in parallel with a nuclear translocation of β-catenin. These PMN-elastase induced alterations of cells are compatible with an epithelial-to-mesenchymal transition (EMT) of the cancer cells. Following EMT, the cells displayed a more migratory phenotype. In human biopsies, neutrophil infiltration was seen in 72% of the cases. PMN infiltrates were detected preferentially in areas with low E-cadherin expression.

Conclusion: PMN in the microenvironment of OvCa can alter tumor cells towards a mesenchymal and migratory phenotype.

Keywords: Ovarian cancer, neutrophils, neutrophil elastase, tumor microenvironment, epithelial to mesenchymal transition, migration.