Multicellular regulation of miR-196a-5p and miR-425-5 from adipose stem cell-derived exosomes and cardiac repair.

Cardiac transplantation of adipose-derived stem cells (ASC) modulates the post-myocardial infarction (post-MI) repair response. Biomolecules secreted or shuttled within extracellular vesicles, such as exosomes, may participate in the concerted response. We investigated the exosome's microRNAs due to their capacity to fine-tune gene expression, potentially affecting the multicellular repair response. We profiled and quantified rat ASC-exosome miRNAs and used bioinformatics to select uncharacterized miRNAs down-regulated in post-MI related to cardiac repair. We selected and validated miR-196a-5p and miR-425-5p as candidates for the concerted response in neonatal cardiomyocytes, cardiac fibroblasts, endothelial cells, and macrophages using a high-content screening platform. Both miRNAs prevented cardiomyocyte ischemia-induced mitochondrial dysfunction and reactive oxygen species production, increased angiogenesis, and polarized macrophages toward the anti-inflammatory M2 immunophenotype. Moreover, miR-196a-5p reduced and reversed myofibroblast activation and decreased collagen expression. Our data provide evidence that the exosome-derived miR-196a-5p and miR-425-5p influence biological processes critical to the concerted multicellular repair response post-MI.

High type I collagen density fails to increase breast cancer stem cell phenotype.

Breast cancer is a highly frequent and lethal malignancy which metastasis and relapse frequently associates with the existence of breast cancer stem cells (CSCs). CSCs are undifferentiated, aggressive and highly resistant to therapy, with traits modulated by microenvironmental cells and the extracellular matrix (ECM), a biologically complex and dynamic structure composed mainly by type I collagen (Col-I). Col-I enrichment in the tumor-associated ECM leads to microenvironment stiffness and higher tumor aggressiveness and metastatic potential. While Col-I is also known to induce tumor stemness, it is unknown if such effect is dependent of Col-I density. To answer this question, we evaluated the stemness phenotype of MDA-MB-231 and MCF-7 human breast cancer cells cultured within gels of varying Col-I densities. High Col-I density increased CD44+CD24- breast cancer stem cell (BCSC) immunophenotype but failed to potentiate Col-I fiber alignment, cell self-renewal and clonogenicity in MDA-MB-231 cells. In MCF-7 cells, high Col-I density decreased total levels of variant CD44 (CD44v). Common to both cell types, high Col-I density induced neither markers related to CSC nor those related with mechanically-induced cell response. We conclude that high Col-I density per se is not sufficient to fully develop the BCSC phenotype.

AHNAK enables mammary carcinoma cells to produce extracellular vesicles that increase neighboring fibroblast cell motility.

Extracellular vesicles play important roles in tumor development. Many components of these structures, including microvesicles and exosomes, have been defined. However, mechanisms by which extracellular vesicles affect tumor progression are not fully understood. Here, we investigated vesicular communication between mammary carcinoma cells and neighboring nontransformed mammary fibroblasts. Nonbiased proteomic analysis found that over 1% of the entire proteome is represented in these vesicles, with the neuroblast differentiation associated protein AHNAK and annexin A2 being the most abundant. In particular, AHNAK was found to be the most prominent component of these vesicles based on peptide number, and appeared necessary for their formation. In addition, we report here that carcinoma cells produce vesicles that promote the migration of recipient fibroblasts. These data suggest that AHNAK enables mammary carcinoma cells to produce and release extracellular vesicles that cause disruption of the stroma by surrounding fibroblasts. This paradigm reveals fundamental mechanisms by which vesicular communication between carcinoma cells and stromal cells can promote cancer progression in the tumor microenvironment.