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-β receptor signaling, enhancing phosphorylation of SMAD2 and SMAD4 nuclear translocation in MCF-7 cells. Treatment with Kistrin (Kr), a specific ligand of integrin αvβ3 EMT induced by MDA-ECM, inhibited TGF-β 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-β receptor signaling pathway. The data evidenced novel potential targets for antimetastatic breast cancer therapies.

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.

Altered extracellular matrix (ECM), a hallmark of solid tumors, affects cellular survival, migration and differentiation. Typically viewed as tumor-suppressive, evidence suggests that apoptosis can also generate pro-tumoral signals. We previously showed that ECM from high-grade astrocytomas induces extensive endothelial anoikis, while a surviving subpopulation fails to form tubular structures (tubulogenesis-defective endothelial cells, or TDECs). We combined functional assays with whole-cell proteomics to investigate this response. Using real-time video microscopy, we found that apoptotic endothelial cells induced by tumor ECM attracted migrating endothelial cells and guided sprouting. Conditioned media from apoptotic endothelial cells contained a 2.8-fold increase in extracellular vesicles (EVs) relative to autologous ECM-primed endothelial cells. Although both EV populations improved TDEC tubulogenesis, only EVs produced upon tumor-ECM stimulation induced TDEC migration—a property lost when using EVs secreted by endothelial cells growing on TN-C-depleted matrices. Proteomic profiling revealed that TDECs shift from an adhesion-anchored to a microtubule-rich and glycolytically rewired phenotype, with upregulation of vesicle-trafficking regulators (ARF1/3/4, ANXA2/5), migration drivers (RAC1/3, RHOA/C, WDR1, FSCN1) and glycolytic enzymes (ENO1, ALDOA, PKM, LDHA), alongside the suppression of integrin- and cytoskeletal-anchoring proteins. Collectively, these findings indicate that tumor-ECM-driven endothelial apoptosis generates reversible reprogramming and an EV-mediated autocrine mechanism that may favor angiogenic balance.