Pro-adhesive phenotype of normal endothelial cells responding to metastatic breast cancer cell conditioned medium is linked to NFκB-mediated transcriptomic regulation

Abstract

Tumor microenvironment is an important promoter of tumorigenesis in all forms of breast cancer and has been associated with the risk of metastasis in the different breast cancer subtypes including the more frequent luminal subtypes that encompass 60% of cancer patients. Adhesive properties of endothelial cells (ECs) are strikingly affected during cancer cell dissemination and are related to functional changes of adhesion receptors. The contribution of tumor secreted factors to tumor-EC adhesion represents a therapeutic opportunity for breast cancer metastasis. Conditioned medium (CM) of tumor cells can be used as a model to study the role of the secreted molecules to the tumor microenvironment. We explored transcriptomic changes associated to a pro-adhesive phenotype in primary human umbilical vein endothelial cells (HUVECs) treated with CM of the breast cancer cell line ZR75.30 or with TNF for 3 h. Selected genes were used to validate the microarray through RT-qPCR. The bioinformatic analysis identified NFκB as the main regulator of the pro-adhesive phenotype and this was confirmed by pharmacological inhibition of NFκB pathway with BAY 11-7085. The changes induced by ZR75.30-CM mimic those promoted by TNF and display changes in the expression of genes related to inflammatory response, wound healing, extracellular matrix, cytokines, metabolism and cell communication. Despite the abundance of G-CSF, IL-8, IL-6 and VEGF in the ZR75.30-CM and the confirmed activation of STAT3 and VEGFR2 pathways, our results suggest dominance of NFκB as a central controller of the transcriptomic response of ECs to breast cancer cells leading to expression of cell adhesion receptors.