Localized heat induces ERK activation and signal propagation in solid tumors.

Localized plasmonic heating by metallic nanoparticles offers a promising strategy to destroy cancer cells through controlled thermal stress. However, how cells sense and respond to microscale temperature variations within complex tissue environments remains unclear. Here, we investigate how plasmon-induced local heating reshapes intercellular signaling and cell fate within tumor spheroids, focusing on the extracellular signal-regulated kinase (ERK) pathway. HeLa spheroids expressing a FRET-based ERK biosensor were subjected to defined photothermal stimuli using gold nanostars as nanoscale heat sources, while ERK activity was tracked with a deep-learning algorithm (3DeeCellTracker). Local heating triggered marked alterations in ERK signaling dynamics compared to spontaneous activity, including changes in activation frequency, timing, and duration. Remarkably, heat-induced ERK activation spread across neighboring cells, revealing thermally mediated intercellular propagation. Quantitative analysis further showed that temperature elevation modulates cell death and division in a power-dependent manner. These results uncover how nanoscale heat generation governs signaling networks and collective cellular behavior, providing a mechanistic framework to understand and optimize heat-based cancer treatment strategies.