Matrix stiffness drives squamous cell carcinoma progression via a Piezo1-mediated mechanotransduction feedback loop

• This work provides the first demonstration that increased matrix stiffness promotes SCC proliferation and invasion through the Piezo1-RCC2 (non-Hippo)-YAP signaling axis. • Our study reveals firstly that matrix stiffness-induced activation of Piezo1 in tumor cells can remodel fibroblasts via a paracrine mechanism, further enhancing matrix stiffness and establishing a positive feedback loop that exacerbates SCC progression. • This research establishes the inaugural evidence that Piezo1 serves as the pivotal mechano-decoder translating biomechanical cues into clinical outcomes, with its expression level independently predicting DFS in cutaneous SCC patients. Squamous cell carcinoma (SCC) is one of the most frequent solid tumor accounting for more than one million cancer deaths annually. Emerging evidence highlights the critical role of mechanical signaling in tumor progression, yet the mechanobiological interplay between extracellular matrix (ECM) stiffness and SCC pathogenesis remains poorly understood. This study aimed to investigate how matrix stiffness drives SCC progression via Piezo1-mediated mechanotransduction and its clinical implications. Atomic force microscopy quantified tissue stiffness in human cutaneous, oral, and lung SCC samples. Spatial transcriptomics and single-cell RNA sequencing (scRNA-seq) analyzed ECM- and mechanoreceptor-related gene expression. In vitro models using tunable-stiffness gels assessed SCC cell proliferation, invasion, and Piezo1/YAP activity. Xenograft models evaluated Piezo1′s role in tumor growth and stiffness regulation. Clinical correlation studies analyzed Piezo1 expression and outcomes in a cutaneous SCC cohort (n = 53). SCC tissues exhibited elevated stiffness compared to adjacent normal tissues. Stiff matrices activated Piezo1, promoting proliferation and invasion in SCC cells via a non-canonical Hippo pathway involving RCC2. Piezo1 knockdown reduced tumor growth and stiffness in vivo. Mechanistically, Piezo1 activation induced TGFβ1 secretion, driving fibroblast-to-myofibroblast transition and collagen deposition, thereby reinforcing matrix stiffness. Clinically, high Piezo1 expression correlated with poor differentiation ( p = 0.0034), recurrence ( p = 0.047), and shorter disease-free survival (HR = 181.03, p = 0.01). This study identifies a self-reinforcing Piezo1-RCC2-YAP axis that translates mechanical cues into pro-tumorigenic signaling, fostering fibroblast-mediated ECM remodeling. Piezo1 emerges as a prognostic biomarker and therapeutic target to disrupt stiffness-driven SCC progression