Obese adipose tissue extracellular vesicles raise breast cancer cell malignancy.

Obesity is a chronic low-grade inflammatory condition that strongly impacts breast cancer. Aside from inflammatory mediators, obese adipose tissue (AT) secretes high amounts of extracellular vesicles (EVs), which are capable of transferring molecules to target cells and promoting cell-to-cell communication. Here, we investigated how soluble mediators and EVs secreted by human obese AT influence MCF-7 and MDA-MB-231 mammary adenocarcinoma cell lines by modulating cell proliferation, migration, invasion, and signaling pathways. Both cell lineages were stimulated with conditioned media (CM) or EVs obtained from cultures of AT explants collected from lean or obese individuals who underwent plastic or bariatric surgeries, respectively. EVs derived from obese AT increased the proliferative potential of both cell lines and further potentiated the migratory and invasive properties of MDA-MB-231 cells. The proliferative effects of CM and EVs on MCF-7 cells were dependent on ERK/MAPK pathway activation, while the migration and invasiveness of MDA-MB-231 cells were dependent on PI3K/AKT pathway activation. Furthermore, CM derived from obese AT potentiated the pro-angiogenic effect of MDA-MB-231 on endothelial cells. We also detected that EVs derived from obese AT were enriched in leptin and bioactive matrix metallopeptidase 9 (MMP9), and stimulation of MDA-MD-231 cells with those EVs or CM derived from obese AT potentiated the release of MMP9 by those cells. Our data indicate that obese AT secretes molecules and EVs with pro-tumoral activities capable of increasing breast cancer cell malignancy and provide strong evidence of the key role of AT-derived EV signaling in the tumor microenvironment.

Extracellular Matrix Derived from High Metastatic Human Breast Cancer Triggers Epithelial-Mesenchymal Transition in Epithelial Breast Cancer Cells through αvß3 Integrin.

Alterations in the composition and architecture of the extracellular matrix (ECM) can influence cancer growth and dissemination. During epithelial-mesenchymal transition (EMT), epithelial cells assume a mesenchymal cell phenotype, changing their adhesion profiles from cell-cell contacts to cell-matrix interactions, contributing to metastasis. Breast cancer cells present at different stages of differentiation, producing distinct ECMs in the same tumor mass. However, the contribution of ECM derived from metastatic tumor cells to EMT is unclear. Here, we showed the mechanisms involved in the interaction of MCF-7, a low-metastatic, epithelial breast cancer cell line, with the ECM produced by a high metastatic breast tumor cell, MDA-MB-231 (MDA-ECM). MDA-ECM induced morphological changes in MCF-7 cells, decreased the levels of E-cadherin, up-regulated mesenchymal markers, and augmented cell migration. These changes were accompanied by the activation of integrin-associated signaling, with increased phosphorylation of FAK, ERK, and AKT and activation canonical TGF-ß receptor signaling, enhancing phosphorylation of SMAD2 and SMAD4 nuclear translocation in MCF-7 cells. Treatment with Kistrin (Kr), a specific ligand of integrin αvß3 EMT induced by MDA-ECM, inhibited TGF-ß receptor signaling in treated MCF-7 cells. Our results revealed that after interaction with the ECM produced by a high metastatic breast cancer cell, MCF-7 cells lost their characteristic epithelial phenotype undergoing EMT, an effect modulated by integrin signaling in crosstalk with TGF-ß receptor signaling pathway. The data evidenced novel potential targets for antimetastatic breast cancer therapies.

Molecular and Cellular Risk Assessment of Healthy Human Cells and Cancer Human Cells Exposed to Nanoparticles.

: Nanodrugs have in recent years been a subject of great debate. In 2017 alone, almost 50 nanodrugs were approved for clinical use worldwide. Despite the advantages related to nanodrugs/nanomedicine, there is still a lack of information regarding the biological safety, as the real behavior of these nanodrugs in the body. In order to better understand these aspects, in this study, we evaluated the effect of polylactic acid (PLA) nanoparticles (NPs) and magnetic core mesoporous silica nanoparticles (MMSN), of 1000 nm and 50 nm, respectively, on human cells. In this direction we evaluated the cell cycle, cytochemistry, proliferation and tubulogenesis on tumor cells lines: from melanoma (MV3), breast cancer (MCF-7, MDA-MB-213), glioma (U373MG), prostate (PC3), gastric (AGS) and colon adenocarcinoma (HT-29) and non-tumor cell lines: from human melanocyte (NGM), fibroblast (FGH) and endothelial (HUVEC), respectively. The data showed that an acute exposure to both, polymeric nanoparticles or MMSN, did not show any relevant toxic effects on neither tumor cells nor non-tumor cells, suggesting that although nanodrugs may present unrevealed aspects, under acute exposition to human cells they are harmless.

Priming Endothelial Cells With a Melanoma-Derived Extracellular Matrix Triggers the Activation of αvß3/VEGFR2 Axis.

The unique composition of tumor-produced extracellular matrix (ECM) can be a determining factor in changing the profile of endothelial cells in the tumor microenvironment. As the main receptor for ECM proteins, integrins can activate a series of signaling pathways related to cell adhesion, migration, and differentiation of endothelial cells that interact with ECM proteins. We studied the direct impact of the decellularized ECM produced by a highly metastatic human melanoma cell line (MV3) on the activation of endothelial cells and identified the intracellular signaling pathways associated with cell differentiation. Our data show that compared to the ECM derived from a human melanocyte cell line (NGM-ECM), ECM produced by a melanoma cell line (MV3-ECM) is considerably different in ultrastructural organization and composition and possesses a higher content of tenascin-C and laminin and a lower expression of fibronectin. When cultured directly on MV3-ECM, endothelial cells change morphology and show increased adhesion, migration, proliferation, and tubulogenesis. Interaction of endothelial cells with MV3-ECM induces the activation of integrin signaling, increasing FAK phosphorylation and its association with Src, which activates VEGFR2, potentiating the receptor response to VEGF. The blockage of αvß3 integrin inhibited the FAK-Src association and VEGFR activation, thus reducing tubulogenesis. Together, our data suggest that the interaction of endothelial cells with the melanoma-ECM triggers integrin-dependent signaling, leading to Src pathway activation that may potentiate VEGFR2 activation and up-regulate angiogenesis. J. Cell. Physiol. 231: 2464-2473, 2016. © 2016 Wiley Periodicals, Inc.