Cell crowding initiates tumor invasion by triggering a nanoscale topography transition of plasma membranes

During the progression from epithelial neoplasms to invasive carcinoma, uncontrolled cellular growth within a confined space generates pronounced cell crowding. Despite its prevalence, how cancer cells sense and respond to crowding during the early stages of tumor invasion remains poorly understood. Here, using a spontaneous crowding model that mimics the progressive compressive stress produced by proliferating cells, we show that cell crowding induces an invasive phenotype in cancer cells. This phenotypic switch is accompanied by a nanoscale smooth-to-corrugated topography transition (nSCTT) of the plasma membrane. By combining biophysical measurements with mechanical modeling, we demonstrate that cell crowding elevates Laplace pressure while reducing membrane tension to drive the nSCTT of the plasma membrane. nSCTT promotes tumor invasion by disrupting the aggregation of lipid raft-like domains. Finally, we demonstrate that strengthening membrane-to-cortex attachment (MCA) effectively blocks the nSCTT and suppresses tumor invasion in both cell crowding models and mouse xenograft models. Together, these findings reveal that cell crowding initiates tumor invasion through a nanoscale plasma membrane topography transition, providing a framework for understanding how mechanical forces are converted into malignant behavior at the nanoscale. STATEMENT OF SIGNIFICANCE: This study reveals how physical crowding of cancer cells triggers invasion through a previously unknown nanoscale mechanism. We discovered that crowding forces cause the cell membrane to transform from smooth to corrugated at the nanoscale. This topography change breaks apart critical signaling hubs (lipid raft domains) on the membrane, ultimately activating invasive behavior. This work provides a framework for understanding how tumors become malignant under mechanical stress and identifies reinforcing the cell membrane as a potential strategy to block cancer invasion.