Scientists have uncovered evidence that glioblastoma cells can retain a lasting mechanical memory of their surroundings.

Glioblastoma, one of the deadliest forms of brain cancer, spreads by sending tumor cells into surrounding healthy tissue. Along the way, those cells encounter an unusual physical challenge: fluid at the tumor’s invasive edge can be about eight times more viscous than fluid near its dying center.

New research suggests that prolonged exposure to this thicker environment may actually help glioblastoma cells invade. After spending a month in highly viscous fluid, laboratory-grown cancer cells became smaller, more deformable, and better able to squeeze through narrow spaces. Rather than simply slowing their movement, the increased resistance appeared to produce lasting changes in how the cells behaved.