Extracellular Matrix Stiffness Regulates Cancer Stemness in Uveal Melanoma via the PIEZO1-DOT1L Axis

Cancer stemness drives aggressive behavior and treatment resistance in uveal melanoma (UM). This study aimed to investigate how mechanical signals from the extracellular matrix (ECM) regulated UM stemness through the piezo-type mechanosensitive ion channel component 1 (PIEZO1)-disruptor of telomeric silencing 1-like (DOT1L) signaling axis.

PIEZO1 expression was assessed using immunofluorescence in human UM and adjacent normal tissues. Polyacrylamide hydrogel models with tunable stiffness were used to simulate the biomechanical microenvironment in vitro. Stemness was assessed by analyzing colony formation, tumorsphere assays, apoptosis resistance, and expression of the stemness markers NANOG and SOX2. In vivo, ECM stiffness was reduced to examine its effects on UM progression and stemness. The roles of PIEZO1 and DOT1L in ECM stiffness-mediated regulation of stemness were examined both via short-hairpin RNA (shRNA), lentiviral overexpression, and a PIEZO1 agonist.

PIEZO1 was upregulated in UM tissues. In vitro, increased ECM stiffness enhanced UM stemness through PIEZO1. Functioning as a mechanosensor, PIEZO1 promoted DOT1L expression, which consequently upregulated the stemness markers. In vivo, reduced ECM stiffness suppressed tumor growth and downregulated the PIEZO1-DOT1L axis and stemness markers. Inhibition of PIEZO1 or DOT1L diminished stemness properties and tumor growth both in vitro and in vivo.

The PIEZO1-DOT1L axis mediated ECM stiffness-driven stemness and tumor progression in UM. Targeting this mechanotransduction pathway by modulating ECM stiffness or its downstream effectors may provide a novel therapeutic strategy for UM.