Nanoscopic characterization of hepatocytes treated with normoxic and hypoxic tumor-derived exosomes

Hypoxia is a key factor in tumor microenvironments. Tumor-derived exosomes under hypoxia have their functions of communication between local and remote cells, and play an important role in tumor growth and metastasis. However, the effect of tumor-derived exosomes on cell structures and functions under hypoxia is unknown. In this work, the effects of exosomes derived from hepatocellular carcinoma cells (HCC-LM3) under normoxia (N-exos) and hypoxia (H-exos) environments on the biological and physical properties of target cells were stduied. The N-exos promoted the proliferation of hepatocytes (HL-7702) at 1.5 mg/mL, while the H-exos promoted the proliferation of hepatocytes at a lower concentration (1.0 mg/mL). After the cells cultured with the same concentrations of N-exos and H-exos for different time periods, the cell migration was enhanced. The stress fibers of the cells became loose and the cytoskeleton was rearranged, which were time dependent. The changes in morphological and mechanical parameters of the HL-7702 cells were detected by atomic force microscopy (AFM). The results showed that the cell edges became irregular and the filopodia were increased versus the exosomes treatment time. The heights and elastic moduli of cells were reduced. Compared with N-exos, H-exos had a more significant effect on the biological and physical properties of target cells. The results provide a method for studying how tumor-derived exosomes affect the interaction between tumor cells and their hypoxic microenvironment.