Hierarchical F-actin microstructures and multi-passage viscoelasticity evolution in living cancer cells under varying glucose environment

F-actin microstructures dominate cellular viscoelasticity and have been used to identify the migration and malignance of living cancer cells. Diabetic cancer patients suffer from increased metastasis and tumor recurrence. However, the long-term evolution and correlation of F-actin microstructures and viscoelasticity distribution are still poorly understood in living cancer cells under varying glucose environment. Herein, by using atomic force microscopy with amplitude modulation-frequency modulation and nanoindentation mode, we characterized the hierarchical F-actin microstructures and the multi-passage viscoelasticity evolution in living Huh-7 cancer cells transferred from high to low glucose level. The highly oriented stress fibers connected by thinner fiber networks were observed in high glucose environment. The circumferential actin networks composed by straight segment-like fibers and the randomly distributed actin fragments connected by ultrathin crosslinking fibers were observed in low glucose environment. The viscoelasticity within the nucleus and the cytoplasm of living Huh-7 cancer cells showed long-term fluctuations over tens of passages after switching glucose environments. The viscoelasticity of cytoplasm was more responsive to the change of glucose environments than nucleus, which was due to the reorganization of F-actin microstructures. Our work provides the microstructural and nanomechanical understanding on the migration and proliferation of living cancer cells under varying glucose environment.