Expression of Cox-2 in human breast cancer cells as a critical determinant of epithelial-to-mesenchymal transition and invasiveness.


INTRODUCTION Cyclooxygenase-2 (COX-2) is overexpressed in several malignancies and is implicated in breast cancer progression. OBJECTIVES We investigated whether changes in COX-2 expression may affect epithelial-to-mesenchymal transition (EMT) and then invasive potential of human breast cancer cells, in relationship with hypoxia. COX-2-null MCF-7 human breast cancer cells, MCF-7 cells transiently expressing COX-2 and COX-2-expressing MDA-MB-231 cells were employed. RESULTS COX-2 overexpression resulted in downregulation of E-cadherin and β-catenin, upregulation of vimentin, N-cadherin and SNAI1, suggesting EMT occurrence. COX-2-overexpressing MCF-7 cells were also characterized by increased invasiveness and release of matrix-metalloproteinase-9. The above-mentioned characteristics, homologous to those detected in highly invasive MDA-MB-231 cells, were reverted by treatment of COX-2-overexpressing MCF-7 cells with celecoxib, a COX-2-specific inhibitor, partly through the inhibition of COX-2-related intracellular generation of reactive oxygen species. Hypoxia further exacerbated COX-2 expression, EMT changes and invasive ability in both COX-2-overexpressing MCF-7 cells and MDA-MB-231 cells. Finally, immunohistochemistry performed on samples from normal and neoplastic human breast tissues revealed that COX-2-positive malignant cells were also positive for EMT-related antigens, hypoxia-inducible factor (HIF)-2α and the oxidative stress marker heme oxygenase. CONCLUSIONS These findings support the existence of a direct link between COX-2 overexpression, EMT and invasiveness in human breast cancer cells, emphasizing the role of hypoxic microenvironment.

DOI: 10.1517/14728222.2014.860447
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@article{Bocca2014ExpressionOC, title={Expression of Cox-2 in human breast cancer cells as a critical determinant of epithelial-to-mesenchymal transition and invasiveness.}, author={Cl{\'a}udia Bocca and Monica Ievolella and Riccardo Autelli and Manuela Motta and Luciano Mosso and Bruno Torchio and Francesca Bozzo and Stefania Cannito and Claudia Paternostro and Sebastiano Colombatto and Maurizio Parola and Antonella Miglietta}, journal={Expert opinion on therapeutic targets}, year={2014}, volume={18 2}, pages={121-35} }