Matrix stiffness modulated release of spheroid-derived extracellular vesicles and discovery of Piezo1 cargo

Augmented extracellular matrix (ECM) stiffness is a mechanical hallmark of cancer. Mechanotransduction studies have extensively probed the mechanisms by which ECM stiffness regulates intracellular communication. However, the influence of stiffness on intercellular communication aiding tumor progression in three-dimensional microenvironments remains unknown. Small extracellular vesicles (EVs) are communicators of altered biophysical cues to distant sites through EV-ECM interactions and EV-mediated recipient cell-ECM interactions. Here we demonstrate stiffness-mediated modulation of small EVs secretion and cargo from three-dimensional oral squamous cell carcinoma spheroids. Using a spheroid culture platform with varying matrix stiffness properties, we show that small EVs carry parental biomolecular cargo, including mechanosensitive Piezo1 ion channel and adhesion molecule CD44. We comprehensively validate the presence of both markers in our EV populations using proteomic and genetic analysis. Transcriptomic analysis of microRNA and long non-coding RNA cargo of small EVs released from soft and stiff ECM spheroids revealed enrichment of tumorigenic and metastatic profiles in EVs from stiff ECM cultures compared to that of soft ones. Gene set enrichment analysis of a comparative dataset obtained by overlaying spheroid mRNA and EV miRNA profiles identified key oncogenic pathways involved in cell-EV crosstalk in the spheroid model.