Stiffness-mediated paracrine signaling enhances induction of EMT in oral squamous cell carcinoma.

Oral Squamous Cell Carcinoma (OSCC) contains diverse communities of cells within the oral mucosa. A subset of the epithelia is highly responsive to changing niche conditions, resulting in their loss of polarity, epithelial-to-mesenchymal transition (EMT), and invasion in tumor-adjacent stroma. Given the range of cell states, we sought to understand how cytokine-mediated signaling from mesenchymal SCC25 cells or stiffness-induced mesenchymal (simCal27) cells caused EMT in naïve Cal27 epithelial cells. Media conditioned by SCC25 enhanced Cal27 cell migration, nuclear localization of EMT markers, and caused transcriptomic changes related to cytokine response ontological terms. SCC and simCal27 cells have unique cytokine profiles, which when regressed against transcriptomic changes, suggested that higher expression of IL-1a, IL-6, IL-8, Angiogenin, and PAI-1 in conditioned media could drive EMT; upregulation of these cytokines also appears impactful for overall survival and progression-free interval. However, depletion and supplementation assays clearly show that the presence of these specific cytokines is critical to induce a migratory phenotype and that naïve Cal27's motility is regulated by MAPK and AKT signaling pathways; loss or inhibition of these pathways reduced migration. These data suggest that paracrine signals from stiffness-induced mesenchymal cells act via distinct kinase pathways and may be necessary for cooperative dissemination of OSCC.